CALIFORNIA INSTITUTE OF TECHNOLOGY DIVISION OF BIOLOGY

BIOLOGY 1950

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A REPORT FOR THE YEAR 1949-1950 ON THE RESEARCH AND OTHER ACTIVITIES OF THE DIVISION OF BIOLOGY

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Table of Contents

Introduction 1

The Staff 2

Staff Promotions, Awards and Honors 7

Financial Support 8

Physical Plant 9

Visiting Lecturers 10

Lectures Series on Psychoanalysis 11

Virus Symposium 12

Graduates 14

Fellowships and Scholarships 14

Research Activities

Animal Physiology Animal Biochemistry Bio'6rganic Chemistry Embryology Genetics: Gorn Genetics: Drosophila Genetics: Neurospora Immunogentics Plant Biochemistry Plant Physiology Virology: Bacterial Virology: Plant

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BIOLOGY 1950

at the

California Institute of Technology

Introduction

Following World War II many outstanding advances in biology · have been made in laboratories all over the world. To mention only a few of these: Bacteriology has been revolutionized by a group of young investigators using the methods of genetics, cytology, and bio­chemistry. Our knowledge of viruses has been greatly increased, par­ticularly from the biological point of view. Through a growing interest by physicists and physical chemists in biological problems, biophysics has grown rapidly, It has made extensive use of the electron micro­scope, the preparative and analytical centrifurges, the Tiselius electrophoresis apparatus and other techniques completely unknown to the.· biology of a few years ago,

Through its Divisions of Biology and Chemistry, the Institute has made its fair share of contributions to the new biology. During the year under review many specific accomplishments have been recorded. Part of these are mentioned in this report of the Division of Biology and part in the account of the activities of the Division of Chemistry, The convention of separate reports from the two Divisions, desirable as it may be from a purely administrative point of view, is unfortunate in so far as it fails to develop an adequate picture of the joint €hemistry­Biology program at the Institute.

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The Staff

The Divisirn of Biology Staff for the year

as follows: Professors

Ernest G. Anderson, Ph.D. George W. Beadlel, Ph.D., D.Sc. James F. Bonner_i Ph.D. · Henry Borsook, P1h.D., M.D. Max Delbrtick, Phj.D. Sterling Emerson~ Ph.D. Arie Jan Haagen-Smit, Ph.D. Anthonie Van Har.ieveld, Ph.D., M.D. Alfred H. Sturtevant, Ph.D. , D. Sc. Albert Tyler, Ph.ID. Frits W. Went, ~~.D. Cornelius A. G. iiersma, Ph.D.

Research Associates

Gordon A. Alles, 1Ph.D. Charles E. Bradley, D. Sc. Michael Evenari, iPh.D. Henry 0. Eversol~, M.D. William Hiesey~ ~h.D. Albert E. Longle)\, Ph.D. Lillian V. (Mrs. t.H.) Morgan, M.A. Adrian Srb, Ph. Di. Esther Bogen Tietz, Ph.D., M.D. Jean J. Weigle, :Rh.D.

1949-1950 was made up

Genetics Biology Biology

Biochemistry Biology

Genetics Bio-Organic Chemistry

Physiology Genetics

Embryology Plant Physiology

Biology

Biology Biology Biology

Plant Physiology P lant Physiology

Biology Biology

Genetics Biology

Biophysics

1. Carnegie Inf;titution of Washington, Division of Plant Biology, Stanford. !

Associate Professors

Norman H. Horowlitz, Ph.D. Edward B. Lewis, Ph.D. George E. MacGitlitie, M.A.* Herschel K. Mitchiell, Ph.D. Ray D. Owen, PhjD.

* On leave of ~bsence.

H. Eugene Lehman, Ph.D.

Arthur C.

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Giese, !Ph.D.

A.ssistant Professor

Biology Genetics

Biology Biology Biology

Biology

Biology

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Senior Research Fellows

Bernard Axelrod, Ph.D. Clara L. Deasy, Ph D, Jacob W. Dubnoff, Ph.D. Renato Dulbecco, Ph. D, Arthur W. Galston, Ph.D.

Geoffrey Keighley, Ph.D. Edward Novitski, Ph.D. Samuel G. Wildman, Ph.D. John A. Whieldon, M.D.

Gosney Fellows

Barry Commoner, Ph.D. Charles B. Metz, Ph.D. Donald F. Poulson, Ph.D.

Warren P. Spencer, Ph.D. Marshall R. Wheeler, Ph.D.

Research Fellows

Barbarin Arreguin-Lozano, Ph.D. Daniel E. Atkinson, Ph.D. Robert S. Bandurski~ Ph.D. Seymour Benzer~ Ph.D. Guy Ch. Camus,3 Ph.D. E. E. Dale, Ph.D. Ellis P. Darley, Ph.D. Frank H. Dickey, Ph.D. A. H. Doermann, Ph.D. Ellsworth C. Dougherty;'l Ph.D., M.D. Marjorie G. Douglis, Ph.D. William Drell, Ph.D. Marguerite Fling, Ph.D. Dan U. Gers tel, Ph.D. Edwin A. Goldsmith, Ph.D. Malcolm Gordon~ Ph.D. Melvin M. Green, Ph.D. Bayard Hammond, Ph.D. Charles, E. Harrold~ Ph.D. Henry Hellmers? Ph.D. James Hendersonf Ph.D. Urs Leupold, Ph.D. Peter H. Lowy, Doctor and um S. E. Luria, Ph.D.

I. National Research Council Fellow

Clement Markert? Ph.D. Jean Mauron, Ph.D. A. M. Michelson~ Ph.D. Mary H. Mitchell, M.A. Rosalind Morris ? Ph . D. Marion Richards Myles, Ph.D. Edwin A. Phillips, Ph.D. Bruno Rosenfeld, Ph.D. Allan Scott ,1 0 Ph. D. Oscar W. Shadle~ M. D. Harold Millard Smith, M. D. Roger Y. Stanier, Ph.D. Melvin L. Stehsel, Ph.D. Gunther Stent? Ph.D. Carl M. Stevens, Ph.D. Edward C. Stone, Ph.D. Arthur G. R. Strickland, Ph.D. Howard J. Teas, Ph.D. Albert UlrichP Ph.D. James Watson, Ph.D. Wolfhard Weidel~ Ph.D. Elie Wollman~ M.D. C. M. Woodworth, Ph.D. Marko Zalokar, D. Sc.

7. U. S. Forest Service 2. Atomic Energy Commission Fellow 8. Commonwealth Fund Fellow 3. Rockefeller Foundation Fellow 4. American Cancer Society Fellow 5. Merck Fellow 6. University of London Fellow

9. University of Nebraska Johnson Faculty Fellow

10. U. S. Public Health Fellow 11. University of California, Berkeley

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Graduate Fellows and Assistants i

I George H. Bowen~ Jr., B. S. Howard Boroughs ,j B. A. George R. Dubes,iB. S. George L. Ellman;, M. S. Norman E. Good, 1B. A. Francis A. Haskirls, M. S.

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Lionel F. Jaffe, a. S. Leonard Jansen, El. S. Edwin B. Kurtz, ti'I. S.

' Chi••g-I-Is:iim"·Li, iB. S. Dan L. Lindsley, M. A.

James L. Liverman, B. S. Jean Nitsch, M. S. Kenneth Paigen, A. B. Earl Patterson, B. S. Irving Rappaport, B. A. Donald Robertson, A. B. Albert Siegel, B. A. Bernard Strauss, B. S. Philips. Thayer, M. S. Emanuel Windsor, B. S. Martynas Yeas, B. S.

Graduate Students

Roderick Clayton,j B. S. J. Luther Eggma~, B. S. F. R. S. Fincham!, B. A. Glenn A. Fischer) B. A. Henry Gershowitz ~, B. A. Willoughby GoodSrhith, M. A. David Hogness, B, S.

Herbert M. Hull, B. A. John W. McKee, B. S. Wen Kwe Pao, B. A. Jose Reissig, B. S. San-Chiun Shen, B. S. Frederick Wolfgram, A. B.

Visiting Graduate Students

Andre T. Jagendorf, B. A. R. M. Manyik, B~ A.

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Jesse E. Skoss, M. S. Michael Yarmolinsky

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Research Assistants

Elsie H. Atkinson, M.S. Rosamond Scott Baker, B.A. Elizabeth Ann Bartron, B. A. Barbara Bostwick, B.A. Jean M. Campbell, M.s: Suzanne ·E. Chute, A. B. Ruth Corbett, B. A. Constance M. Dimmick Joanne E. Donovan, B.A. Mary E. Durrell, M.S. Amelia A. Dvorsky, M.S. Phyllis Ellman, M. S.

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Mary E. Emerson, M.A. Ruth E. Estey Helen R. Fahy Leola E. Ford, M.S. Margaret M. Fox, B.S. Mildred Gordon, M. S. Emma Jane Griffith, B.S, FrankN. Hirosawa, M.S. Mary M. Hull, B.A.

* Air PQllution Control District

Helen E. Jeffrey, R. N. Nylan Jeung, B.A. Jean Jones, B.A. Marcella C. Juhren, M.A.

, May G. Keighley, B.S. 'Robert Tor Lofbergf B.A.

Carol Lotz, M.A. Madeleine Mattli Luescher, Ph.D. Marjorie M. Mathews, A.B. Alice R. McColloch, B .S. Anna c;;. Newton, M.S. Marilyn B. Rusler, A.B. Margaret I. Sellers, M.S. Roy E. Signer, M.S. Ruth E . Singer , A . B • Helen Surber, M.S. Tiao Hsin Wang, M.s,. Wiaczeslau Wichtynskyj, M. D. Betty Jean Wood, B.S. Milton Zaitlin, B.S.

Laboratory Technicians

Clara W. Brainerd Shirley Fisher William Hudson

Arthur W. Abbott Lyle C. Bacon Mitchell B. Bain Harold K. Coulter John M. Dodge Brian F. Doolin Leora F. Duberg Ernest Dzendolet Richard H. Fuller A. J. Grafman James G. Helmuth Shigeru I. Honda John M. Kelleher

Janet V. Johnstone Eleanor L. Kerr

Technical Assistants

Henry C. Kirk Matt Meselson Karl Niedermann Thelma Niedermann Gilbert Peppin Carl A. Price Zane Price Audre Richardson James A. Ross, Jr. Glenn A. Swinehart Charles G. Walance Edith M. Wallace

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Laboratory Assistants

David Beadle Egon Bittner Solomon D. Chase

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Thomas P, Coons .i Robert Freeman j

Wladyslaw Galeck~ Paul!"'le M. Garan4 Aidan R. Gough ' Olga Hill Gunn Dale A. Heffner Bruno Herscovici Ann Hewetson Donald Lamar Suzan Laufer Eric Lindvall Sudie Newman Peter J, Pauling Theodore D. Pletsich

Harry Bemis

Patrick A. Burke AndrewDrummon4 Raymond S. Dunba\r

Henry Gilcher I

Victor J. Fritschi E. J. Griffith

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Evelyn Anderson, frypist Virginia Carr, Typist . Delores Craton, S~cretary

Custodians

Gard~ners

Library

Office Staff

Dorothy S. Egbert> Secretary Gerald Fling, Adrr:\inistrative Ass't. Marjorie Krenz, Sf'cretary

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Morris Robkin Victoria Rodekohr Judith Rodekohr William Shuck Henry Sturtevant Jerrold Turner Esther Van Niel Peter H. Verdier Charles Von Berg Selina Weinbaum Cora Wells Ruth L. Wendt Anneke Went Hans A. Went Jess Williams William N. Williams John S. Winslow

W. A. Bowness

Albert Miotto Donald V. Parker Kenneth Woods

Shirley Kavenau Irene Young

Elizabeth Land, Secretary Helen Lilly, Secretary Hilda Rook, Chief Clerk Pamela M, Rowbotham, Secretary Mary Ann Stofer, Secretary

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Shops

Henry A. Garand, Division Mechanic A, J, Nunn, Maintenance Carpenter

L. E. Castle, Jr. , Supervisor R. W. Gibbons, Assistant

Stockroom

Frank L. Ostrander, Mechanic Ray E. Stofer, Mechanic

George A. Zentmyer, Assistant

Superintendents

C. W. Cochran, Arcadia Experimental Farm George G. Chalmers, Kerckhoff Marine Station G. P. Keyes, Earhart Plant Research Laboratory Charles M, Newman, Orlando Greenhouse

It should be pointed out that the total 271 is somewhat misleading in that it includes a number of persons who were at the Institute for only a part of the year and an additional number of part-time employees.

Staff Promotions, Awards, and Honors

Edward B. Lewis, promoted from Assistant Professor to Associate Professor. Herschel~. Mitchell, promoted from Senior Research Fellow to Associate Professor. George E. MacGinitie, granted leave of absence to serve as Scientific Director of the Arctic Research Laboratory, Point Barrow, Alaska. Albert Tyler, granted leave of absence for the winter quarter to accept an appoint­ment as Walker-Ames Visiting Professor in the Department of Zoology of the University of Washington. Arthur W. Gals to~ awarded a Guggenheim Fellowship to work in the laboratory of Hugo Theorell of Stockholm, Sweden. Arie J, Haagen-Smit, given the Fritzsche Award by the American Chemical Society for "outstanding achievement in analysis, research, and new applications of essential oils." Wm. ~· Hiesey, with two fellow staff members of the Carnegie Institution of Washington, awarded the Mary Soper Pope Medal by the Cranbrook Institute of Science for "distinguished accomplishment in botany during 1949. '.' Warren P. Spencer, awarded the Leidy medal by the Academy of Natural Sciences of Philadelphia "for his distinguished studies and for his stimulating undergraduate teaching that has inspired able young men to go on to scientific careers." James Bonner, elected to the National Academy of Sciences.

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Financial Support

The rapidity with which the cost of scientific research increases is not encouraging to those charged with keeping programs going and budgets balanced. The funds used for various purposes by the Division during the 1949-50 year came from the following sources:

Institute Endowment Funds

William G. and Louise E. Kerckhoff Fund Rockefeller Foundation Endowment A. C. Balch Fund Laurabelle Arms Robinson Fund

Frank P. Hixon Foundation Fund

Gosney Research Fund Charles B. Holder Fund Lucy Mason Clark Fund

Special Non-Endowment Funds

American Cancer Society American Cancer Society American Cancer Society James B. Boswell Foundation California Wine Advisory Board Coe Chemical Company

Earhart Foundation

Eversole Lecture Fund Hermdn Frasch International Mineral and Chemical Corporation Loomis Institute for Scientific Research Los Angeles County Air Pollution District

F. S. Markham Fund Merck Company Fund

National Foundation for Infantile Paralysis Nutrition Foundation

Purpose

General biology General biology General biology Biology and chemistry as related to cancer research Neurophysiology, physiological psychology and related fields Gosney fellowships General biology Plant physiology fellowship

Chemical genetics Plant tissue culture Sulfonamide action Virus researc·h Wine constituents Veratrum growth and alkaloid production. Earhart Plant Re.search Laboratory Seminar speakers Plant physiology Creatine research Special biology expenditures Smog constituents and smog plant damage Electroencephalography (a) Chemically induced

mutation (b) Isolation of new growth

factors Virus and related research Amino acid and vitamin biosynthesis and utilization in Neurospora

Pioneer Hi-Bred Fund Research Corporation Rockefeller Foundation Fund

Edward G. Robinson Fund Leonard G. Strater Fund

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Elbridge and Mary Stuart Foundation Sugar Research Foundation University of California - Beet Sugar Fund U.S. Atomic Energy Commission (Administered by Office of Naval Research, U.S. Navy)

U.S. Atomic Energy Commission (Administered by Office of Naval Research, U.S. Navy)

U.S. Navy, Office of Naval Research U.S. Public Health Service U.S. Public Health Service

Physical Plant

Fellowship Tryptophane-nicotinic acid Joint chemistry-biology program Electronarcosis Plant physiology Milk protein:; research Plant physiology Sugar beet research

Radiation genetics

Protein synthesis Guayule rubber research Mammailian physiology Transmethylation

Earhart Laboratory The year 1949-50 saw the completion of the Earhart Laboratory for Plant Researeh, and the development in it of many active research programs. It has become evident that smog damage to plants is a serious limit­ing factor in many projects in Earhart. Accordingly a vigorous attempt was made to find out how smog can be excluded. It was found that activated carbon filters will do this effectively. Accordingly, plans have been completed and funds appropri­ated to install such filters in the main air intake system.

Marine Station The cooperative agreement between the Institute and Pomona College whereby Pomona's marine zoology instruction is given at the Marine Station during a five-week period in the summer has been extended for two years. On the basis of this agreement several alterations have been made. Chief among these is the installation of a roof canvas canopy which provides 11200 square feet of dormitory space. This makes available bunk space for 24 students. On the second floor a dressing and shower room has been outfitted.

Main Kerckhoff Building Many laboratories have been remodeled and reconditioned for research and teaching. The largest single enterprise consisted in completely remodeling rooms 105 and 106 for effective teaching of elementary biology courses .

Library Largely through the efforts of a cooperative and efficient General Library Staff, substantial further progress was made in building up the Division Library. During this year, 1,553 periodical volumes and 449 books were added. These essential and welcome additions have forced a solution to the problem of how and where to find additional library space. Plans have been completed and funds appropriated for the installation of eight bookcases in the main Kerckhoff

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libn<b•y. These will be made of walnut to match existing shelving and paneling and will substantially increase book capacity without seriously modifying the appearance of the room.

An extremely valuable addition to the Biology Library collections has come through the gift of approximately 1, 100 volumes by Mrs. Ira W. Clokey and her daughters, Mrs. W. M. Houghton and Mrs. Robert M: Mayer. This gift repre­sents the private library of the late Ira W. Clokey, who for many years after his retirement as a mining engineer devoted his time to a study of native western plants. In addition Mr. Clokey worked for a number of years in plant genetics with Pro­fessor E. G. Anderson at the Arcadia Farm. The Clokey collection has been named the Ira W. Clokey Botanical Library. Its volumes, marked with a special bookplate designed by Roger Hayward, fill many gaps in the Division Library.

Friends of the late Oliver B. Scott, partner in the Los Angeles investment firm of Maxwell, Marshall and Company and a former Institute student (1921-1923), have established a fund known as the Oliver B. Scott Memorial Fund. It is being used for the purchase of appropriate books bearing on medical aspects of biology. These will be marked by a special bookplate.

Substantial progress was made by Scripps College artist Albert Stewart on the Morgan Memorial described in last year'r-s: report. When completed this will be placed in the Division Library opposite the portrait of Mr. Kerckhoff.

Visiting Lecturers

During the year seventeen seminars were given by visiting lecturers. In many instances travel assistance was provided these visitors from the Eversole Lecture Fund. Speakers and their subjects were as follows:

Doctor Berthe Delaporte, ·:0arnegie Institution of Washington, "On the Cytology of Bacteria"

Doctor Sunder! Hora, India, "Adaptation of Torrential Stream Fishes"

Doctor E. D. Adrian, Cambridge, England; "Olfactory Discrimination"

Professor C. Hyman, University of Southern California, "Physical Factors in Capillary Filtration"

Professor A. M. Schechtman, University of California at Los Angeles, "Development of the Blood Serum in the Embryo, with Special Reference to

the Transfer of Large Molecules"

Professor T. L. Jahn, University of California at Los Angeles, "The Electroretinogram of Insects"

Doctor H. M. Kalckar, University of Copenhagen (Eversole Fund), "Metabolism of Purines"

Doctor N. E. Tolbert, University of Wisconsin (Everso.le Fund), "a~ Hydroxy Acid Oxidase of Leaves"

Professor Benson E. Ginsburg, University of Chicago (Hixon Fund), "Physiology of Gene Controlled Seizures"

Professor Melvin Calvin, University of California, Berkeley (Eversole Fund), "Path of Carbon in Photosynthesis"

Doctor D. W. Taylor, Stanford University (Hixon Fund), "Selection of Men for Training as Scientists"

Doctor Carl L. Hubbs, Scripps Institute of Oceanographia (Eversofe Fund), "Sex in the Cetacea"

Professor John W. Gofman, University of California, Berkeley (Eversole Fund), "The Ultracentrifuge in the Study of Arteriosclerosis"

Doctor Marjorie Douglis, Department of Zoology, University of Chicago, "Physiological Sociology and Human Behavior"

Doctor Spencer Paterson, University of London, "Electronarcosis as a Treatment for Mental Diseases"

Doctor H. VE!ldstra, Quinine Institute, Amsterdam, "Chemical Structure and Physiological Activity"

Doctor R. J. Winzler, Department of Biochemistry, University of Southern California, "Interrelationship of Carbohydrate and Amino Acid Metabolism in Excised Tissues"

Lecture Series c ~Psychoanalysis

With financial assistance from the Hixon Fund, the Division sponsored a series of five lectures on the general subject "The Scientific Basis of Psycho­analysis." These were as follows:

Professor Ernest R. Hilgard, Stanford University, "Experimental Approaches to Psychoanalysis" (Two lectures)

Doctor Lawrence S. Kubie, New York City, Yale University School of Medicine, "Problems and Techniques of Validation in Psychoanalysis" (Two lectures)

Doctor E, P. Mindlin, Veterans Administration, Los Angeles, "The Position of Psychoanalysis in the Biological and Social Sciences"

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This series of lectures was so well received that it was decided by the Hixon Committee that it should be published. With concurrence of the participants, plans for this were made. Doctor Mindlin has consented to serve as editor,

Virus Symposium

During 1949-50 there was established at the Institute by the James G. Boswell Foundation a special fund for virus research. In giving consideration to the question of how best to advance knowledge in this important field, Institute staff members have spent much time and thought. In this they have been given generous help by Doctor Lawrence A. Williams, who has served as a special advisor to both the Boswell Foundation and the Institute. It was early decided that an important pre­liminary to expanding the Institute's present research program in virology was a thorough exploration of existing knowledge in the field. To this end a special con­ference of outstanding virologists was held in March, 1950. Max DelbrUck, who was largely responsible for planning and managing the conference, described its back­ground, aims, and organization, as follows:

"Animal and plant viruses are of great practical importance because they are disease producing agents. As such they are of interest to pathologists, and research in this direction is heavily sponsored by medicine and by animal and plant industry. This research aims directly at the control of specific virus diseases, but notwith­standing the expenditure of great effort practical success has been very limited. It is true that we have learned something about the natural history of a number of the disease producing agents and that some of them have been isolated and partially characterized but this is not enough to suggest remedies. What is needed .is an understanding of the behaviour of viruses within their hosts. How do the viruses invade host cells, how do they multiply, how do they interrupt and modify the normal functions of the host cell? These are the problems of virus research which tie this research into the great stream of modern biology aiming at the analysis of cellular functional organization.

11 The conference which gave rise. to the proceedings here presented arose from the desire to bring the men who work on the three great groups of viruses, those which atta·ck animals, plants, and bacteria, respectively, into one room and to discuss whether and to .what extent our respective charges can be brought under one hat. We felt that such a move could be profitable only if each of us did some con­siderable home work of a double nature, namely, that of preparing an intelligible statement concerning his own specialty and that of studying the prepared statements of the others. To set a background to the general. approach an essay by Luria, which had just been submitted for publication in Science, was circulated among the pro­spective participants. The preliminary statements were also circulated, and were .studied and discussed at home and en route by .smaller groups out here and by those who had arranged to make the long trip West together. The conference was in face proceeding for quite some time before it met as a whole, and it continued for some of

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us for three days after the meeting around camp fires in Death Valley. When it met as a whole a great deal of formality could be dispensed with. The authors of the preliminary statements confined themselves to briefly recalling the highlights of their papers and then laid themselves open to questions from the floor, of which there were many."*

After the conference was well under way those taking part agreed that pub­lication of the proceedings would serve a useful purpose. Professor Delbrlick undertook the job of editing the material cand arranging for publication. In this, and particularly in handling details with the printer and in proof-reading, he had the able assistance of the Division Administrative Assistant, Mr. Gerald Fling. In fact, somewhat of a publishing record was established. The manuscript was ready for the press in May and the printer delivered the 147-page bound volumes in July, just two months after the manuscript was given to him.

The participants, other than the fifteen Institute staff members who took part, were:

Ander son, T. F. --University of Pennsylvania Bald, J. G. --University of California at Los Angeles Bawden, F. C. --Rothamsted Experimental Station, England Bennett, C. W.--Sugar Beet Station of the U.S. Department of Agriculture

at Riverside, California Bergold, G. --Laboratory of Insect Pathology of Canada Evans, C. A. --University of Washington Fraser, Dean--University of California at Berkeley Hershey, A.D.--Washington University, St. Louis Hirst, George K, --New York City Public Health Research Institute Knight, C .A. -- University of California at Berkeley Luria, S.E.--Indiana University Mountain, Isabel Morgan, formerly with Johns Hopkins University Pardee, A. B .--University of California at Berkeley Putnam, F .W .--University of Chicago Schachman, H.K. --University of California at Berkeley Schlesinger, R. W .--New York City Public Health Research Institute Shope, R .E .--Merck Institute for Therapeutic Research, Rahway, New Jersey Stanley, W.M.--University of California Wallace, J. M .--University of California Citrus Experiment Station, River side,

California ' Winzler, R.J.--University of Southern Ca~lifornia

With the virus conference as a background, plans are underway to strengthen and extend the program of virus research of the Institute.

>I; "Viruses 1950", editedbyM. Delbrlick, p. 4, 1950.

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Graduates

Five men were awarded B. S. degrees with options in Biology. All are planning to go on for advanced work. Raymond Brow will attend the University of Southern California Medical School, Shigeru Honda will take graduate work in plant physiology at the University of Wisconsin, Jerry Mathews will take graduate work at the University of Southern California, Wheeler North has been awarded a fellowship at the Scripps Institution of Oceanography to work toward a Ph.D. degree in biochemistry, and Bruce Stowe will take graduate work in plant physiology at Harvard University.

Seven men completed work for advanced degrees during or soon after the year under review. Ching Hsiung Li, M.S. in Plant Physiology, Wen Kwe Pao, Ph.D. in Genetics, and San-Chiun Shen, Ph.D. in Genetics, have returned to China. Kenneth Paigen, Ph.D. in Biochemistry, has been awarded a Carnegie Institution of Washington Postdoctoral Fellowship to work in the Carnegie Institution's Genetics Laboratory at Cold Spring Harbor, Long Island. Bernard Strauss, Ph.D. in Biochemistry, has joined the staff of the University of Texas, Department of Zoology, as a postdoctoral Research Fellow. Emanuel Windsor, Ph.D. in Biochemistry, is not yet certain of his plans. Martynas Yeas, Ph.D. in Embryology, has joined the faculty of the Department of Zoology, University of Washington.

Fellowships and Scholarships

Gosney Fellowships appointments, namely:

During the year five men held Gosney Fellowship

Barry Commoner, Associate Professor of Botany, Washington University, St. Louis, Missouri.

Charles B. Metz, Assistant Professor of Zoology, Yale University, New Haven, Connecticut.

Donald F. Poulson, Associate Professor of Genetics, Osborn Zoological Laboratory, Yale University, New Haven, Connecticut.

Warren P. Spencer, Professor of Biology, College of Wooster, Wooster,· Ohio.

Marshall R. Wheeler, Instructor, Department of Zoology, University of Texas, Austin, Texas.

McCallum Graduate Fellowship Through the Nutrition Foundation and the Mc Callum Foundation, Mr. Arthur Mc Callum established a graduate fellowship for work in chemical genetics, biochemistry and other fields related to nutrition. The first award of this was made for the academic year 1950-51 to George L. Ellman, graduate student working toward a Ph.D. degree in chemistry with Professor Mitchell.

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Lucy Mason Clark Fellowship in Plant Physiology This fellowship, established last yea:;:-;-v;as awarded for the first time in 1949-50 to Mr. Jean P. Nitsch, who is completing work for a Ph.D. degree with Professor. Went.

Seeley W. Mudd Scholarship This undergraduate scholarship, established by Doctor Seeley G. Mudd for students interested in medicine and medical research, was held during l 'l49-50 by Mr. Wheeler North. Mr. North will work toward a Ph.D. degree at the Scripps Institution of Oceanography of the University of Cali­fornia with the ultimate goal of investigating aging from a biochemical standpoint.

Thomas Hunt Morgan Scholarship The first award of this scholarship, estab­lished by friend;-;;fthe late Professor Morgan, was made for 1949-50 to Fre.shman Robert Wood. Mr. Wood demonstrated his worthiness by ranking well toward the top of his class .

Other Fellowships

During 1949-50, fifteen persons carried on postdoctoral research in the Division on fellowships awarded by agencies other than the Institute. These were distributed as follows:

Rockefeller Foundation Fellow 3 Merck Fellows of the National

Research Council National Research Council

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Fellow in the Natural Sciences 1 American Cancer Society Fellow 2 Commonwealth Fund Fellows 2 Atomic Energy Commission

Fellow 1 University of London Fellow 1 University of Nebraska Johnson

Faculty Fellow 1 United States Public Health Fellow 1

Five graduate students held nationally awarded predoctoral fellowship as follows:

Atomic Energy Commission U.S. Public Health Service

2 3

In connection with nationally awarded postdoctoral fellowships, it is a fact of interest that of 24 Merck Fellowships awards made during the three years 1947, 1948 and 1949, four were to men from the Institute, and nine were to men who elected to work at the Institute. This is a record of which the Institute has reason to be proud.

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Research Activities

Animal Physiology

Comparative Physiology. Assisted by Mr. Doolin, Professor Wiersma has continued to investigate effects which can be brought about by impulses in a single crustacean motor fiber when the pattern of the impulses is varied From older experiments it seemed that the hermit crab would be the most appropriate animal for this purpose. Since the larger hermit crabs formerly found at Corona del Mar had vanished, it was decided that these experiments could be best done at the Zoological Station in Den Helder, where a good supply was guaranteed. It was possible to show conclusively that either fast or slow contractions of the opener muscle could be obtained, depending on the impulse sequence. The explanation is thought to be due to the presence of two types of nerve endings on the same muscle fibers which differ in the way they react to the impulse sequence. As far as is known, this is the first preparation in which such a great difference in reaction is present on impulse pattern variation, It may thus serve as a model for transmission in the central nervous system and shows that the restrictions in possibilities caused by the all­or-none relation of nerve impulses do not need to be so great as has been believed,

Another series of experhnents is under way in which a preparation is studied of the central nervous system of the crayfish. In this a single impulse in a single preganglionic fiber causes a row of impulses in a peripheral root. From all indi­cations most of these latter impulses are set up in the same motor fiber. A further study of such preparations seems promising. The phenomena found may be con­sidered to form a bridge between the group of synapses which act only when peripheral sensory stimulation is present and phenomena which occur "spontaneously" without such stimulation. They re pre sent a contribution to the comparative physiology of synapses in showing that the normal concept of a synapse as a place where more than one impulse must arrive before transmission can take place represents only one of several possibilities.

With the aid of the two-beam cathode ray oscillograph it is now possible to study symmetrical roots and to see what the difference in effect is between the one on the same side as the stimulated central fiber and the one on the opposite side. At first it appears as if this difference is slight, but closer study shows that although the two sides have almost identical discharges, slight differences iri timing and in number of impulses do occur. Further study of these differences may well contribute to a solution of the problem of how symmetrical body movements are caused.

Mammalian Physiology. Professor Van Harrev~ld has collaborated with Doctor Whieldon, Doctor Shadle, Doctor Smith, Miss Estey, Mrs. Kerr and Mr .. Wolfgram in continuing his work in mammalian physiology. As pointed out in last year's report, Van Harreveld has developed a mathematical model of the mammalian blood circulation which includes the parameters of the lung circulation. From this model it is possible to make predictions which can be put to a tesL Shadle and Van Harreveld have experimentally tested a number of these predictions. In general the

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findings in the animal experiments agree well with those predicted. The effects of pentobarbital and epinephrine administration on the circulation were analysed. It was concluded that the well known rise in blood pressure which follows intra­venous epinephrine injection is not produced primarily by arteriolar contraction (increase of peripheral resistance) but by an increase of blood flow owing to an enhanced tone of the large blood vessels and to the beneficial effect of epinephrine on the heart.

Smith and Van Harreveld investigated the possibility of a sympathetic sensory skin innervation, It is well known that the sympathetic carries sensory fibers for the intestine. That sensory fibers for the skin pass through the sympathetic chain is usually denied. In cats a number of dermatomes (from Th 10 until 4) were isolated by severing spinal roots cranial and spinal roots caudal of the dermatome under investigation. The extent of the dermatome was carefully investigated and its limits tattooed on the skin. Then the sympathetic chain was removed and after recovery of the animal the boundary of the dermatome was again determined. It was found with veryJew exceptions that the dermatome became smaller after sym­pathectomy. A small usually triangular area situated at the cranioventral side of the dermatome became anesthetic, This area is probably not the extent of the sympathetic sensory innervation of the dermatome, but is the region where the somatic and sympathetic sensory innervations of the dermatome do not coincide. The existence of a sympathetic sensory skin innervation is definitely established by this work.

Wolfgram has investigated the existence of a special small fiber system in frog muscle as claimed by Kupfler and Gerard. Although the experiments described by these workers could in general be repeated, another explanation was proposed. Against the assumption that the features of this small fiber system are those of a well defined anatomical entity in the frog muscle, arguments were presented that the properti:es of the small fiber system are those of exhausted muscle fibers. By a combination of asphyxiation and faradic stimulation it was possible to produce the small fiber contraction in any frog muscle, including those muscles in which Kupfler and Gerard were unable to elicit it.

In a series of experiments supported by a grant from the U. S. Public Health Service, Van Harreveld studied the effect of asphyxiation on the potassium content of mammalian nerve. Definite indications were found that the nerve can maintain its high K content only in the presence of substrate (glucose) and oxygen. Asphyxi­ation results under all circumstances in a loss of K. This supports the concept that the high K content inside the axon is the result of a steady state, in which the pumping of K into the axon by an energy-requiring process balances its tendency to leak out. These findings are in contradiction with work from Fenn who, using frog nerve, did not find a loss of K during asphyxiation.

Supported by the Merrill Fund, Van Harreveld and assistants have attempted to demonstrate histologically the branching of the intact motor nerve fibers which he postulated previously would constitute the mechanism by which marked functional improvements can occur in a muscle from which a large part of its innervation had been removed. After trying a considerable number of silver impregnation methods, that of Cagal (pyridine-silver) was found to be useful. A considerable number of

- 18 -

preparations are now on hand in which newly regenerated nerve fibers and young end-plates can be found, the presence of which can be explained only by the increased branching of the motor nerve fibers which escaped destruction in the

initial partial denervation.

Whieldon and Van Harreveld have continued and extended their electro­encephalographic studies of experimentally, induced depression of cortical activity of the brain---studies made possible by the F. S. Markham Fund,

Assisted by the Edward G. Robinson Fund, Doctor Tietz devoted part time to a study of the physiological effects of electronarcosis on experimental animals.

Animal Biochemistry

During the last year, operating under the joint sponsorship of the Atomic Energy Commission and the Naval Research Office of the U, S. Navy, Professor Borsook, Professor Haagen-Smit and a group of collaborators including Doctor Keighley, Doctor Deasy, Mrs Keighley, Miss Rusler, Mrs. Dvorsky, Miss Jeffrey, Mrs .. Garand, Mrs. \\erH1t and several part-time technical assistants, have continued studies of the biological synthesis of proteins.

The incorporation of amino acids into proteins is found to be very much faster than. was hitherto suspected. When an amino acid is .introduced into the blood stream most of it is incorporated into the tissues of the proteins in about one-half hour. The most active tissues are the viscera. About one-half hour later there is a migra­tion of labeled protein from the viscera to the blood, and in one hour the blood and viscera are in balan.ce. The speed of this process suggested that amino acids are converted first into a reactive form that is then incorporated into the proteins. Some evidence is.no·w at hand that this is the case. and a barium salt of a compound that may be such a reactive intermediate has been isolated.

A year ago there was found in the livers and other tissues of several animals a fraction consisting of a large peptide that had the physiological and chemical properties of an intermediate in protein synthesis. It is intermediate in size and also incorporates labeled amino acids in vivo and in vitro more rapidly than do the proteins. Thii;; year methods have bee~developed for the purification of this peptide fraction. It is .interesting that several papers have appeared by other workers in which a similar or identical fraction has been found in micro-organisms and tumors. There is evidently a good deal of interest now in a number of laboratories in the large peptide fraction of tissues, To continue this work a grant of $ 5, 000 has been made to the Division by the Eli Lilly Company and Dr. A. Abrams has been appointed to pursue the purification, and if possible, the crystallization of this peptide fraction.

During the last few months a soluble enzyme has been isolated .which incor­porates histidine into proteins with great speed. This is the first instance in which amino acids have been incorporated into proteins in vitro. with a particle-free enzyme preparation. Purification of this enzyme and a study of its properties are now under way.

'

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The protein synthesis project necessitates the measurement of the radio­activity of a great many samples. Though there are three manually operated counters for this, it frequently happens that these measurements fall behind the rest of the work. Many hours by skilled people are spent on this routine procedure. To alleviate this situation Keighley has designed and supervised the construction of an automatic sample counter. This is unlike anything previously built. The machine has a capacity of 100 or more samples at a time. The samples are counted for a predetermined time, after which the total number of counts, the number of the sample and the length of time the sample was counted are printed on a paper tape. Not only can such a device run unattended, but it can work at nights and over weekends, and thus accomplish a good deal of work with little attention.

Doctor Dubnoff, with support from the U. S. Public Health Service and with the assistance of Mrs. Jones and Mrs. Singer, has characterized the biochemical mechanism of vitamin B 12 action and its specific effect in sparing methyl groups in the animaL It was found that very small amounts of this vitamin increased the rate of reduction of glutathione, a compound whose state of reduction is known to influence a wide variety of enzyme systems. The effect on methylation was shown to be indirect. Since the vitamin also increases the formation of homocysteine from homocystine it influences methionine formation by providing the methyl acceptor homocystine. The evidence suggests that this vitamin activity is due to a coenzyme form since the crystalline material is inactive in liver while certain preparations of it have been shown to become active in the presence of kidney tissue. (See also research activities, Bio-organic Chemistry.)

Doctor Rosenfeld, Research Fellow from the Weizmann Institute of Science, Israel, has worked on the mechanism of the irreversible oxidation of ascorbic acid (vitamin C) and its biological significance. From experiments in which radioactive ascorbic acid was fed guinea pigs it \\as found that a part of the radioactivity appears in oxalic acid excreted in the urine.

Mr. Paigen, graduate student under the sponsorship of Borsook, has completed his thesis research on the source. of urea carbon in the rat.

Mr. Windsor, graduate student working with Borsook, has shown the existence of a-aminoadipic acid in some plant proteins. A year ago it was found that this amino acid is one of the first steps in the metabolism of lysine in animals. Evidence has since been obtained that a-aminoadipic acid is not present in animal tissues.

Bio-organic Chemistry

Under the direction of Haagen-Smit, the Bio-organic Chemistry laboratories have been actively interested in several projects. Haagen-Smit has continued the study of natural products, especially essential oils. In collaboration with Doctor N. Mirov of the Forestry Genetics Department at Berkeley, the oleoresins of Pinus strobus, P. cembra, P. taeda, P. radiata, P. virginiana, P. lambertiana, P. ponderosa, P. banksiana-:- P. canariensis, P . .;;-shoensis, P. flexilis, P. aristata,

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p. balfouriana and P. parviflora were investigated. Three new sesquiterpenes and a diterpene were isolated from these sources. These investigations bring the number of analyzed species to approximately half those recognized in the genus Pinus.

Doctor Bradley has continued the study of the essential oils and latex of desert plants. The oils of Pectis papposa and Burs era microphylla, and the latex, Mammilaria McDougalii, have been analyzed.

Under contract with the California Wine Advisory Board, the study of the volatile products from Zinfandel grapes was concluded, and a study of the wine made from these grapes is being carried out by Mr. Hirosawa. The fermentation products of the amino acids are of great importance in the flavor development of wine. Doctor Strickland has therefore determined quantitatively the amino acids present in the non-volatile material from the grapes.

With assistance from the Elbridge and Mary Stuart Foundation, a project was started on the composition of milk, and special attention is being given by Doctor Goldsmith to the proteoses. These have been isolated, and it is expected that a better knowledge of the chemical constituents will throw more light upon the flavor changes which occur in milk.

Haagen-Smit' s laboratory has continued to collaborate with Borsook in studies on protein synthesis. For this purpose, several amino acids labelled with radio­active carbon have been synthesized by Doctor Lowy and Miss Bartron. Some of the products in which the isotope is pre sent after incorporation into a tissue are being isolated. These products are of peptide nature, and similar material is found among, the products resulting from partial hydrolysis of serum albumin', , Parallel studies on the products from both sources are being conducted by Miss Fox to establish methods of isolation and the sequence in which the amino acids occur. (See also report of research activities in Animal Biochemistry.)

Haagen-Smit has continued his studies of air pollution and has demonstrated the importance of oxidation of organic material as a inajor contributor to smog. This work is being conducted in cooperation with the Los Angeles Air Pollution Control District, the Scientific Committee of the Los Angeles Chamber of Commerce, and the Stanford Research Institute.

The microanalytical laboratory, through Mr. Swinehart, continues to provide service to several research groups in both Biology and Chemistry.

Embryology

During the past year Professor Tyler has continued to study mainly problems of fertilization and early development in marine invertebrates. In this he has been assisted by Miss Sellers, Mrs. Atkinson and Mrs. McColloch. One aspect of this work is the elucidation of the chemical nature of specific egg- and sperm- substances that interact in serological manner and that provide part of the mechanism for the specific union of the gametes. Certain of these substances were previously isolated

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in relatively pure form. Most progress has been made with the substance known as fertilizin, which represents the surface coat of the egg. This substance is a glycoprotein (contains both sugars and amino acids) and is chemically related to such physiologically interesting substa11ces as the human blood group substances and heparin. A number of the different amino acids and sugars that comprise the molecule have now been identified and certain differences have been found with fertilizin of different related species of sea urchins.

During the winter quarter, which he spent at the University of Washington, Tyler investigated the occurrence and propertie·s of these substances in various species of trout. There had been some doubt that substances analogous to fertilizin and antifertilizin could be obtained from eggs and sperm of vertebrates. However, these substances proved to be readily extractable from the fish gametes and the typical agglutinative and other reactions obtained with them. Chemically the fertilizin of trout eggs differs markedly from that of sea urchins. Further in­vestigation of its nature is in progress,

In the course of investigations of the action on sperm of various enzymes that affect fertilizin and antifertilizin, and of certain amino acids and sugars that these substances contain, it was accidentally found that a considerable im­provement in the fertilizing capacity of the sperm was obtained by the addition of various amino acids. The addition of amino acids is found to extend very greatly the functional life span of the spermatozoa of various marine invertebrates. For example, in a solution of O. 05 molar glycine in sea water, sea urchin sperm sur­vive more than 50 times their normal life span. Alanine, valine, leucine and lysine, as well as the peptide glutathione, are also active in this respect. The present evidence suggests that these amino acids act by retarding the dissolution of antifertilizin, which constitutes part of the surface of the head of the sperma­tozoon. The amino acids maintain the spermatozoa in a state of high activity and must, therefore, also have a significant metabolic action, which is being investi­gated initially on the basis of effects on respiratory rate. Aside from its bearing on problems of fertilization and sperm metabolism, this finding may have utility for the practice of artificial insemination, which is now employed very extensively with farm animals, and for possible alleviation of certain types of human male sterility.

Doctor Metz, with the help of Miss Donovan as Research Assistant, resumed certain investigations that he had begun as a graduate student on the agglutination of starfish sperm by fertilizin of the species. Ordinarily no visible reaction occurs. Metz had found that certain proteins act as adjuvants in enabling the fertilizin to cause specific visible agglutination of the sperm. Concurrent with Tyler's findings on the action of amino acids on sea urchin sperm, Metz tested these in the starfish system and found that they also acted as adjuvants. Having a rapid test system he was able to investigate in a relatively short time a large number of amino acids, peptides and other substances. He found all the a-amino acids tested to be effective. From various tests Metz interprets the results as an action on the antifertilizin of the sperm, such that more specific combining groups are made available for

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interaction with fertilizin. Further serological interest attaches to this finding in that in many immunological systems there is no visible agglutination or precipi­tation. This occurs very often, for example, in the case of the human Rh system, and it had been found by Wiener and others, following Metz' s earlier work on adju­vants, that the addition of certain non-specific proteins would induce the occurrence of agglutination in such systems. There is, then, the possibility that amino acids may be effective in such systems, too.

Doctor Yeas has investigated the respiratory enzymes of sea urchin eggs. It has been maintained by many embryologists that the enzyme systems of the adult tissues are quite different from those of the egg, and that they are established through synthesis of various enzymes during development. His investigations show, with high probability, that oxidations in the egg proceed over the same pathways as has been demonstrated in adult tissues of various animals.

Mr. Jaffee has been devising technical means for preparing mass cultures of the different types of cells that are formed in the early cleavage of sea urchin eggs, so that he can determine whether or not there are physico-chemical differ­ences in cells of different prospective development fate.

Doctor Scott of Union College, Schenectady, New York, completed a nine months' stay at the Institute in August 1949. With a grant in aid from the U. S. Public Health Service, he investigated the relationship of redox agents to the visible structure of marine eggs.

Genetics: Corn

Through a U. S. Atomic Energy Commission sponsored contract adminis­tered through the U. S. Navy, Office of Naval Research, Professor Anderson and a group of co-workers are continuing a series of investigations having to do with the cytological, genetic and biochemical nature of radiation induced gene and chromo­some mutstions in Indian corn. Material exposed as dry seeds at Bikini and Eniwetok has been extensively studied and compared with similar material exposed to known dosages of X-rays and with untreated control material. In studying chromosome aberrations, particularly translocations, Doctor Longley finds that radiation induced breaks are not randomly distributed within the various chromo­somes and he shows differences in comparable material treated with X-rays and with bomb radiation. A large number of gene mutations from treated material have been collected. The more promising of these are being used in genetic and biochemical studies.

Doctor Teas has continued studies on a mutant type showing blue fluorescence under ultraviolet radiation, Anthranilic acid has been chemically identified as one of several compounds responsible for the fluorescence.

Doctor Bandurski has studied chlorophyll precursors in albino mutant types that show a tendency to germinate prematurely. These possess protochlorophyll but are unable to convert it into chlorophyll. They also lack fl-carotene. These facts suggest that the mutant involves a block in the synthesis of the phytyl component of the chlorophyll molecule. Such an interpretation is consistent with the behavior of a genetically unstable albino mutant type observed by Anderson.

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The tryptophane-nicain-auxin interrelations have been studied in normal strains by Doctor Stehsel and in relation to seven endosperm mutant types by Teas and Miss Newton.

Mr. Robertson is completing genetic and physiological studies on mutant 'types in which seeds show premature germination.

Anderson and Mr. Patterson have concerned themselves with the develop­ment of chromosome techniques for the detection and control of genes for traits which are of economic value. These techniques are based largely on the use of chromosome translocations and inversions obtained from radiation treatment. It is believed that they will have an important practical application in enabling the corn breeder to tag traits that he desires to transfer from one strain to another. Much of the actual testing of these techniques as tools in plant breeding is being done in cooperation with the U. S. Department of Agriculture, the Pioneer Seed Company of Johnston, Iowa, and certain of the corn belt agricultural experiment stations.

Miss Bostwick and Miss Ford, Research Assistants, helped to carry out these investigations.

Mr. Dubes, a Graduate Student, who has been doing chromatographic analyses of pigments in chlorophyll mutants, has shifted his field from corn to Neurospora genetics.

Genetics: Drosophila

During the year the Kerckhoff third floor Drosophila genetics groups consisted of Professor Sturtevant'. Mrs. Morgan, Doctor Lewis, Doctor Novitski, Doctor Spencer, Doctor Poulson, _Doctor Whe.eler, Doctor Green, Mr. Lindsley, Mr. GoodSmith,plus the Research Assistants, Miss Chute, Mrs. Fahy and Miss Griffith.

In addition to their genetic and taxonomic work on Drosophila species, Sturtevant and Wheeler undertook a rather extensive taxonomic study of certain of the sm,all diptera.

Spencer investigated local populations of Drosophila simulans with respect to the frequency of occurrence of mutant genes showing visible effects.

Lewis continued his interest in the manner in which the immediate products of genes interact before they leave the site of the chomosomes. The results permit a picture of gene action which may be described in terms of analogy. A set of three genes has been found which lie very close to one another and act like adjacent operators along an assembly line. Each gene has a specific step to carry out in a series of chemical reactions leading to a product essential for development. The intermediate products must be immediately available for the next gene in the series and here the chromosome becomes the conveyor belt of the system. There are, however, two such conveyor belts (each chromosome being present twice) and the evidence suggests that products may drift across from one assembly line to the other. The elucidation

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of such a system is being attacked, by (1) removing specific operators in one or the other off both assembly lines (removing genes or causing them to mutate) and (2) widely separating the two assembly lines in space (production of chromosomal rearrangements by X-ray). The effects of these operations are then studied in terms of changes in development of the organism. One practical result has been the development of a new genetic method of detecting chromosomal rearrange­ments, which may be regarded as the most rapid method of detecting such changes yet available.

Novitski continued to study the question of why flies X-rayed at low temper­atures show a higher frequency of sex-linked lethals than do those treated with equal doses at higher temperatures. He also undertook a study to determine experi­mentally if the existence of a chromosome rearrangement in a chromosome would influence the distribution of new induced rearrangements. In certain cases a:t least the~ seems to be a clear yes.

A third project carried on by Novitski involved an analysis of the second division distribution of two structurally unequal members of a chromosome pair in Drosophila meUi.n,o gaster. The evidence indicates quite clearly that, in cases in which the separating chromosomes are an attached X chromosome complex and a smaller ring-X chromosome or two rod chromosomes of unequal size, there is a marked tendency for the smaller of the two separating members to be preferentially included in the egg nucleus. This finding may possibly be related to the deviation from a one-to-one sex ratio regularly observed in certain animals.including man.

Lindsley has undertaken a study of crossing over between X and Y chromosomes in the male of Drosophila melanogaster.

Genetics: Neurospora

Professor Emerson, with assistance from Doctor Wichtynskyj, has continued studies on the interrelations of carbohydrate metabolism and the synthesis of certain amino acids in Neurospora, particularly methionine and threonine. With Doctor Zalokar of the University of Washington he has made further contributions to an understanding of the so-called sulfa-requiring strain of Neurospora which, under certain conditions, will not grow unless supplied with one of the sulfonamide drugs.

Doctor Pao, completed his Ph.D. thesis work with Emerson on a "Thermo­phobic" mutant strain which appears to show manifold effects of a single gene. This strain fails to grow normally at high temperatures on certain carbohydrates and shows characteristics that appear superficially to be unrelated. It appears on careful study that the various propetti~ can all be referred to abnormal sensitivity to acetate and other breakdown products of carbohydrate metabolism.

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Mr. Reissig has undertaken studies of beta-amino acid deaminases and has achieved some success in his attempts to separate this enzyme from others.

Mrs. Emerson has done further work on the chemical activation of Neurospora ascospores and has initiated studies of a so-called "osmotic mutant".

Doctor Harrold, University of London Postdoctoral Research FeUow, has extended his studies of mutant strains of Neurospora that require the amino acid serine for growth.

Professor Mitchell has collaborated with several persons on a number of projects. One of these that has occupied a good deal of time for several years involves the interrelation of the amino acid tryptophane and the vitamin niacin. Mr. Haskins, a graduate student working with Mitchell, has demonstrated the existence of a cyclic metabolism of tryptophane in Neurospora, the accumulation of kynurenic acid by one mutant, and the utilization of 3-hydroXy-kynurenine as a precursor of niacin. Haskins, Doctor Nye and Doctor Gordon, collaborating with Mitchell, have shown that quinic acid promotes growth of a mutant that will use phenylalanine, tryptophane or tyrosine. This suggests a common origin of the aromatic amino acids.

Doctor Dr ell has developed a method for chromatographic separation and qualitative identification of the purines and pyrimidines known to exist in biological systems.

Doctor Michelson has worked on the synthesis and characterization of orotic acid riboside.

Two genetic types of histidine mutants in Neurospora have been studied by Mrs. Mitchell and a substance related to histidine has been isolated from one type. The substance is not formed by the double mutant but it has no biological activity for the mutant that blocks its synthesis. All the histidine mutants are inhibited by a basic amino acid other than histidine plus nearly any other amino acid. None of the histidine-requiring mutants grows on complete medium.

, Mr. Good has shown a-amino- € -hydroxycaproic add to be an intermediate, following a-aminoadipic acid in the biosynthesis of lysine in,Neurospora. Doctor Mauron, working with Mitchell, has made extensive tests of four mutants that evi­dently require unknown substances in liver extract and of three that require substances in peptone. The required substances have been purified to some extent. The method for selection of "unknown" mutants has been improved.

Mr. Ellman is attempting to find mutants that require phospholipids or their constituents. He has also developed chromatographic methods for the separation of known phosphate esters.

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Mrs. Mitchell has demonstrated extensive changes in metabolism, only indirectly related to a particular gene mutation, by investigating accumulations of substances not directly related to the mutant's requirement. Thus a lysine mutant and a temperature sensitive lethal mutant accumulate considerable amounts of uracil. The lysine, histidine and arginine mutants accumulate a -ketoisovaleric acid (ketovaline). Some of them also accul:nulate pyruvic acid as do all the genetic types of uridine mutants. The adenine mutants,wild type and a considerable variety of other mutants do not accumulate significant quantities of these substances. A valine mutant accumulates an as yet unidentified keto acid.

Ellman and Mitchell have synthesized peptides containing methylanthranilate to be used as substrates for chymotrypsin. With these it is possible to investigate enzyme kinetics at great dilution by use of the high sensitivity of fluorescence de­terminations.

Mitchell has studied the chromatographic properties of crystalline chymotrypsin and amylase.

In a cooperative .study of fluoro-substituted amino acids being carried out with Professor Nieman of the Chemistry Division, Mitchell and Mrs. Ellman have further tested mono-fluoro ring-substituted isomers of phenylalanine, tyrosine and tryptophane as inhibitors for various microorganisms, higher plants and mammals. A high species specific difference has been found. For example m-fluorophenylalanine is very toxic to mice while the ortho and para derivatives are relatively non-toxic. The compounds are about equally toxic to certain bacteria. The therapeutic value of these agents has not been extensively investigated except to show that the ortho and para derivatives do not protect mice against pneumococcus and to find that they have some arresting action on c 3H tumor transplants. In the latter case they are probably of little or no practical value. The toxicity of m-fluorophenylalanine for mice appears to be due to its metabolism to fluoroacetate.

Doctor Dougherty, Senior Research Fellow of the American Cancer Society, working part time at the University of California and part time at the Institute, has continued his genetic and nutritional studies on certain free-living nematodes which for a number of reasons are well suited to studies in physiological and embryqlogical

,';'"

genetics.

Professor Horowitz has collaborated with Be search Fellows Fling and Leupold and Graduate Students Strauss, Shen, Thayer, Gershowitz and Fischer in several projects.

Doctor Fling has completed isolation of threoni: ne from a mutant blocked between cysteine and cystathionine. Isolation of the other intermediate accumulated by this strain is almost complete. A crystalline product has been obtained which has been tentatively identified as homoserine. If further analysis of the product bears this out, this will be the first isolation of this amino acid from a natural source.

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Doctor Leupold has obtained six temperature mutants in~. coli, four of which involve dispensable losses, and two indispensable losses. A synthetic medium has been obtained for Schizosaccharoniyces pombe, making this interesting yeast available for biochemical genetic studies.

Strauss has completed his study of B6 ~~~ants. The effect of pli on growth

of certain of these mutants is not an effect on the n:iold, but on the composition of the medium: they require a high concentrations+oi · ·~~h for growth when B6 is not supplied, and,this is favored by high pH. Inability to'''u'se nitrate, even when supplied withNH3 , appears to be due to the fact that NH3 is assimilated before 'NOj is used. By the time N03- begins to be reduced, the NH3 concentration has dropped below the critical level.

Shen in an analysis of a single-gene mutant requiring both cysteine and tyrosine has shown that the tyrosine requirement is caused by a high tyrosinase content of the mutant. Wild type shows little or no tyrosinase activity. Abnormal activity of this enzyme is a secondary effect of derangement in sulfur metabolism. This is shown by studies with wild type in which the same effect cal). be induced by the addition of excess cysteine to the medium. It is concluded that the mutant gene concerned has only one primary function, and that the gene con!rol of enzyme activity may in some cases be indirect.

Thayer has demonstrated that one of the best substrates for Neurospora L-amino acid oxidase at the pH of the cell (pH6) appears to be canavanine. All wild strains produce the enzyme. Some wild strains are strongly inhibited by canavanine, indicating that the enzyme may be inactive in vivo in these strains, at least with respect to canavanine oxidation. The expla~tion may rest on mutual interference of amino acids on the enzyme surface, a phenomenon recently found by Thayer .

. , Canavanine oxidation is strongly inhibited when arginine, lysine, or methionine is p're'~ent.

Gershowitz has found a new suppressor for the mutant blocked between homocysteine and methionine. Analysis is still in progress.

Fischer has undertaken a study of the enzyme cysteine desulfurase and other aspects of sulfur metabolism in Neurospora.

Doctor Dickey, Research Fellow in Chemistry and Biology, ass.isted by Miss Lotz, has c.ontinued to work on chemically induced mutation in Neurospora.

Last year's demonstration that certain organic peroxides induce reversions to wild type in an adenine-requiring strain of Neurospora has been substantially broadened. A number of new mutagenic agents have been found, including particu­larly mixtures of hydrogen peroxide with a large variety of carbonyllic compounds.

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One,.: such preparation has proved to be more effective than X-rays and nearly as effective as ultraviolet light. Two more genes have been shown to respond to the action of peroxides and genetic analyses have shown that the changes under study here are true mutation. A large part of the work has been directed toward the completion of a quantitative study of the action of five different mutagenic agents on three genes. This has lead to some interesting results and it is felt that an expansion of the investi­gation might permit the drawing of important conclusions about the nature of mutations.

During the summer of 1949, Professor Stevens of Washington State College, investigated the mutagenic effects on Neurospora of the so-called one-armed mustard gases. These were found to possess mutagenic properti.es, a fact of some importance in formulating hypotheses of the mechanism of gene mutation.

Immunogenetic s

Professor Owen, assisted by Mrs. Hull and Mrs. McColloch, has continued several lines of investigation, using serological methods. In collaboration with Senior Research F@ llows Wildman and Singer, the latter of the Chemistry Division, Owen has continued the investigation of higher plant viruses, particularly tobacco mosaic virus, Preliminary results indicated a definite serological relationship between the normal non-particulate cytoplasmic nucleoprotein of the tobacco leaf and the virus believed to be formed from it following infection with tobacco mosaic. In subsequent experiments difficulty was experienced in confirming this result and it is now evident that further study will be necessary before a final answer is at hand. (See also report of research in Virology.}

Owen and Doctor Markert, Merck Research Fellow, have worked together on an immunogenetic study of the tyrosinase system in the fungus Glomerella. Anti• bodies against tyrosinase appear to interfere directly and specifically with the enzyme rather than simply to aggregate it as has been found with certain other enzyme-antibody systems. Studies on wild type and mutant strains of Glomerella, and with strains of the fungi Neurospora and Psalliota, indicate a close parallel between the presence of active enzyme and material with antigenic characteristics of the enzyme. Thus culture conditions and genetic circumstances resulting in virtual absence of the enzyme do not appear to act at some final point at which specificity is imprinted on a limited surface of an available protein character, but seem instead to be associated with absence of the entire antigen in serologically recognizable form. Owen emphasizes that his conclusion is as yet only a tentative one.

With Mitchell, Gordon, and Professor Campbell (Chemistry Division), Owen spent some effort on the fractionation of antibodies with the Mitchell chromatopile. These studies are currently being deferred, pending results of Mitchell's efforts to improve resolution and repeatability of chromatopile protein fractionation.

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Professor Srb of Cornell University spent last summer at the Institute, writing a book on elementary genetics, of which Owen is co-author, to be published by W. H. Freeman and Company.

Mr. Rappaport, Graduate Student working with Borsook and Owen, has found an as yet undefined principle in normal sera that stimulates a synthetic system in intact bone marrow. Antisera that agglutinate the marrow cells do not appear to interfere with this synthetic acitivity.

Plant Biochemistry (See also PianCPhy-sio1 o g y)

The activities of the plant biochemistry group, headed by Professor Bonner, continue to center primarily on the biochemistry of the plant growth hormones. An important development has been the increase of our knowledge concerning the regulation of one of these hormones, indoleacetic acid, in the living plant. It had earlier been shown that an enzyme for the destruction of indoleacetic acid occurs in many plant tissues. This enzyme, known as indoleacetic acid oxidase, .has been studied by Doctor Galston, Senior Research Fie, llow, and his R(i!.search Assistant, Miss Baker, and shown to consist of two separate enzymes, a flavoprotein and a peroxidase. The two enzymes are linked in their activity through the fact that the flavoprotein oxidizes substrate with the production of hydrogen peroxide, which is then utilized by the peroxidase in the further destruction of indoleacetic acid. Inter­estingly enough, the flavoprotein component of this enzyme system is activated by visible light. Owing to this fact, light, either with the enzyme system in vitro or with the living plant, brings about increased destruction of the active plant growth hormone, Many of the morphological ·effects of light on the plant are probably interpretable in terms of this light-activated hormone destruction. As a corollary to this work, it has been shown by Galston and Doctor Bandurski that the phototropic response of mutant albino corn plants -- bending of plants towards the light -- is due, not to light absorbed by carotenoids as was previously thought, but to light absorbed by flavoproteins, presumably by the indoleacetic acid oxidase. Absorption of light by the flavoprotein system results in increased destruction of auxin, the plant growth substance, on the lighted side and in resultant bending of the plant toward the lighted side. Further work has also revealed that a naturally occuring inhibitor of indoleacetic acid oxidase app"ears to be identical with the inorganic element, manganese.

The Division has been extremely fortunate in having Doctor Axelrod, Division of Enzyme Chemistry, Division of Agricultural and Industrial Chemistry, U. S. Department of Agriculture, assigned to its plant biochemistry laboratory for a year. Axelrod is a leader in the field of study of plant enzymes and will not only continue his own work on isolation and characterization of enzymes from plant sources but will also serve as a consultant and advisor to other members of the Division of Biology who become engaged in enzyme isolation.

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Bandurski has also studied the mechanism of biosynthesis of plastid pigments in higher plants, using detached leaf cultures and intact plants. His experiments are consistent either with the hypothesis that the two classes of plastid pigments, the chlorophylls and the ca)·«>tenoids have common percursors, or that a pigment complex of constant composition is formed. Evidence consists of experiments which show that both chlorophyll and carotenoid syntheses increase or decrease in constant proportion in response to inhibitors, added exogenous precursors, and variation in physical factors such as light and temperature. He has made progress in the identification of at least one photochemical reaction involved in carotenoid pigment synthesis.

Mr. Boroughs, a Graduate Student, has been studying the isolation and physiological function of the phosphatase enzyme found in leaves. He has succeeded in effecting a substantial purification of the enzyme.

Mr, Jagendorf. a visiting Graduate Student from Yale University, has investigated the 11·starving leaf" phenomenon. When a leaf is detached from a plant, the protein rapidly disappears even though the leaf is provided with enough light to supply its photosynthetic buds. In collaboration with Wildman it has been found that the particulate proteins disappear much more rapidly than the soluble cytoplasmic proteins, which remain relatively unchanged. In collaboration with Axelrod, they have found that three enzymes, phosphatase, invertase and peroxidase, undergo no change in amount or activity even though as much as 50% of the total protein disappears through catabolism, suggesting that some proteins are spared at the expense of others. Extension of this work is contemplated with the use of radioactive tracers in order to investigate the dynamic equilibrium which exists between plant proteins a_nd their building blocks, the amino acids, since detaching the leaf appears to upset this equilibrium to an extent that protein synthesis is markedly reduced.

Doctor Henderson, Research Fellow, in his studies of the mechanism by which indoleacetic acid is produced in the plant has shown that many plant tissues contain not only the enzyme system for conversion of the amino acid tryptophane to indole­acetic acid, which has been previously described from this laboratory, but also an inhibitor of unknown nature which inhibits the action of the enzyme system. The point to be stre.ssed in the present connection is that the regulation of indoleacetic acid level in the living plant is apparently a highly complex affair, involving as it does enzymes for the formation and destruction of the hormone as well as inhibitors of the two enzyme systems. No doubt further investigation will reveal enzymes for the destruction of the inhibitors, etc.

Doctor Atkinson, Research Fellow, has continued his investigations of the enzyme system which converts tryptophane to indoleacetic acid in the plant. The enzyme has been shown to consist of separate entities, and it has been shown that the separate enzymes involved may be differentiated to some extent by their specificity with regard to substrates. Thus, the enzyme responsible for the final conversion of indoleacetaldehyde to indoleacetic acid will oxidize other related aldehydes to their corre.sponding acids.

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A major project of the laboratory for some time has centered around the study of the flowering process of plants, the process by which vegetative buds are converted to floral primordia. This work has continued to involve primarily plants whose flowering is regulated in nature by relative length of light and dark periods. There are, in particular, plants which flower only when the dark period exceeds a certain critical length. It has been clearly shown that in this process dark periods beyond the critical length result in the formation in the leaves of a hormone of unknown nature which travels to the buds and there brings about floral differentiation. It has been felt for some time, on the basis of numerous kinds of experiments, that this hormone is not a simple organic substance of the nature of other known plant hormones but may possibly be a protein and even virus-like in certain ways. A direct approach to this problem has been initiated, using the methods for the study of plant virus worked out in this laboratory by Doctor Wildman. In addition, however, it has been shown that the production of the flowering hormone in the leaves of the plant is dependent upon the level of auxin of the leaf. Thus, flowering may be inhibited by the application of indoleacetic acid to the leaves of plants kept in dark periods longer than the critical. Contrary­wise, it has been shown earlier and confirmed and extended during the past year that plants placed under conditions where they will not ordinarily flower may be induced to flower by the application to the leaves of auxin antagonists, compounds related to indoleacetic acid but differing slightly in molecular structure. Such antagonists which bring about flowering in certain species are, for example, tri­iodobenzoic acid, The effect of relative length of day and night in controlling flowering appears to be primarily then upon the level of auxin in the leaf.·

It has been shown in earlier work, both at this institution and at others, that plants respond by flowering to a dark period longer than the critical provided only that they have previously been subjected to a light period of adequate length. During the past year it has been shown by appropriate experimentation that this light period may be replaced by the application of sucrose to the plant. The effect of the light period upon the subsequent flowering response during the dark period is thus apparently due to the photosynthetic production of sugar.

The active investigation of the tumors of plants has continued during.the past year under the direction of Doctor Henderson ax;d with the assistance of Mrs .. Luescher, Miss Dimmick and Miss Durrell. It had earlier been shown that tumor tissues of plants differ from related normal tissues in their abHity t<;> produce the auxin, indoleacetic acid. Tumor tissues are able to produce large arnbunts of thi.s material; related normal tissues are unable to do so. During the past year it has been shown that both normal and tumor tissues contain the enzyme for the production of indoleacetic acid from tryptophane. Tumor tissue, however, contains large con­centrations of an inhibitor of the enzyme system, the inhibitor referred to e.arlier in this report. The induction of tumors entails in part at least, then, the disappearance of the inhibitor for production of the growth hormone indoleacetic acid. Doctor Camus, a Rockefeller Foundation Fellow, has been exploring the possibility that the crown gall type of plant tumor results from virus infection. It is already known from the work of Black at the Rockefeller Institute that certain tumors which arise from wounding plants are caused by a virus. Camus has preliminary evidence which suggests that this virus may be extracted from tumorous tissue and identified by electrophoretical

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means, and efforts are being made to apply these methods to oiher tumors whose virus nature has not yet been clearly established.

The tissue culture technique, which has been applied so fruitfully in the past in this laboratory to the study of the hormonal relationships of the different organs of plants, has been applied during the past year to the study of the growth of fruits by Mr. Nits ch and Mr. Jansen, Graduate Students. Three species of fruits have been cultured satisfactorily in the test tube. It has been shown with one species at least that growth of the excised fruit in vitro resembles very closely growth on the normal plant, provided only that suitable mineral nutrients and sugar are provided. In other instances, however, more complicated requirements are in evidence, and a task for the future will be the working out of the exact growth factor requirements for the growth of these organs.

During the past year the Division of Biology through the plant biochemistry group has had an opportunity to contribute to two technological aspects of biology in its relation to agriculture. The first of these has been the contribution to the development of hybrid guayule of increased rubber yielding capacity developed, in part, through the work of Doctor Gerstel and Doctor Hammond, Research Fellows of the Institute, who carried on this work at the Natural Rubber Laboratory of the U. S. Department of Agriculture at Salinas, California. Gers tel and Hammond were supported in this work by a U. S. Navy Office of Naval Research contract administered by the Division of Biology. As a part of this same project, Doctor Arreguin-Lozano has studied the mechanism by which rubber is synthesized by the guayule plant. For two years the Institute has carried on a cooperative program of research with the U. S. Forest Service designed to determine what may be done about the improvement of the growth of plants in the Angeles National Foresi. This work, carried on primarily at the Orlando Greenhouse and in part also in the Earhart Plant Research Laboratory, has shown that the most critical factor in the growth of.plants in our local mountain ranges is the low fertility of the soil. The soil of our mountains is extraordinarily infertile, and large responses to nitrogen and phosphate fertilizer may be obtained. This relatively elementary application of plant physiological science will, it is believed, permit a substantial improvement of plant cover in our local watersheds with resultant decrease in run-off.

Bonner has completed a book on plant biochemistry, which is to be published shortly by the Academic Press. In preparing this and in other activities Bonner has had the able assistance of Mrs. Wood.

Plant Physiology (See also Plant Biochemistry)

With completion of the Earhart Plant Research Laboratory a large pro­portion of the work in plant physiology has been transferred to it. With Professor Went in charge, a group of investigators supported by an able technical staff are carrying on a series of projects, as follows:

Assisted by Miss Weinbaum, Went is studying the effect of temperature, photoperiod, light intensity and light quality on the growth, fruit production, size and photosynthetic efficiency of the tomato, .with a view to determining optimal

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conditions for growth and why, in physiological terms, the optimal conditions are what they are,

Went and Mrs. Corbett, with the financial support and scientific collaboration of the Coe Chemical Company, are growing clones of Veratrum viride, a plant of the lily fa=ily, under various conditions of light and temperature to determine the optimal conditions for commercial growth and the environmental factors that facvor a high content of the alkaloids known to possess antihypertension activity.

One of the major projects in plant physiology is concerned with the local smog problem. There are two principal reasons for being interested in this, viz.,

1. A desire to solve the problems of the composition of smog, its source, and the basis of its harmful effects on plants.

2. The necessity of finding a way of excluding smog from the Earhart Laboratory since it seriously interferes with the growth of many plants.

Through the wholehearted cooperation of the Los Angeles County Air Pollution Control District and the University of California Citrus Experimental Station at Riverside a group of investigators have worked actively on the smog project. These included Went, Haagen-Smit, ·Mr. Hull of the Institute; Doctor Darley and Mr. Zaitlin of the University of California; and Mr. Noble of the Air Pollution Control District. It has been found that compounds formed from hydrocarbon constituents of petroleum oil and gasoline by partial oxidation reproduce typical smog plant damage, Organic peroxides seem clearly to be important offenders. It has been found that the plant-damaging components of natural smog are effectively removed by filtering air through activated charcoal filters. As previously mentioned, plank are under way to install such filters in the main air intake of Earhart.

The smog project is being continued and extended. Haagen-Smit has in fact arranged to spend three-fourths of his time during the coming year working directly with the Los Angeles County Air Pollution Control District.

Doctor Ulrich, assigned to the Earhart Laboratory by the University of California, and his Research Assistants Miss Jeung and Mrs. Juhren have investigated the effects of light, temperature and nutrition on growth and development of sugar beets. This study is a cooperative one between the University of California, the Beet Sugar Research Foundation, and the Institute, with the principal financial support coming from the Beet Sugar Research Foundation.

In a cooperative venture involving the Carnegie Institution of Washington, the United States Forest Service and the Institute, Doctor Hiesey, Mr. Juhren and Went have investigated the germination of certain desert and chaparral species under controlled laboratory conditions and have attempted to correlate these studies with field tests and observations. They have also studied the effects of temperature and prloperiodism on the germination and establishment of various species and

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hybrids of grasses with a view to determining their suitability for erosion control in arid regions, Doctor Hellmers, Research Feilow, assigned to the Institute by the U. S. Forest Service, has undertaken studies of transpiration water loss by California native chaparral plants grown under controlled conditions of light and temperature.

Hiesey has shown that climatic races of the plant Achillea show differential growth responses to varying temperatures. Experiments are in progress now to determine if these same races respond differentially to different light intensities.

Camus has also found, as Went found for the tomato, that the growth and morphology of tobacco plants is profoundly affected by the night temperature. In collaboration with Mr Eggman, a Graduate Student, and Wildman, Cci.mus has made a study of the protoplasmic constitutents, particularly the proteins, of the leaves of tobacco plants grown at constant day temperature and varying night temperatures. Their results suggest that the total amount of protein synthesized by the leaf is constant with night temperature from 6°- l ?"C. However, the pathway of protein S).!:ithesis is profoundly altered by night temperature. With increasing night temperatures, there is a marked increase in the amount of insoluble particulate proteins (chloroplasts, mitochondria, etc.) of the leaf protoplasm,with a con­comitant decrease in the soluble cytoplasmic proteins. Camus is also determining the influence of various amino acids on the growth and photoperiodic reaction of Baeria chrysostoma, a small desert plant of the sunflow!"r family, known as Gold Fields, found suitable for growth in aseptic culture. It is found that amino acids greatly influence both processes.

In addition to the studies reported in the sections on Plant Biochemistry, Mr. Nits ch, Lucy Mason Clark Graduate Fellow in Plant Physiology, has studied the action of photoperiod, light intensity, and day and night temperatures on flower production in the Marshall variety of strawberry.

Mr. Liverman, ci.ppointed Lucy . Mason Clark Graduate Fellow in Plant Physiology for 1950-51, has undertaken a study of the environmental factors that influence the growth and vegetative reproduction of several species of Bryophyllum. Plantlet production is found to be dependent on the photoperiod to which the mother plant is subjected.

Mr. Kurtz, Graduate Student, and Liverman have collaborated in studies of the influence of water supply on production of wax and alkaloids by Nicotiana species. SOJ'Ilewhat similar studies are being carried on with corn in which waxes and sugars are being followed and also with the creosote bush.

Hiesey, who was appointed Research Associate at the Institute for the summer in order to take charge of the Earhart Laboratory during the absence of Went, is on the staff of the Carnegie Institution of Washington, Plant Biology Laboratory, .Stanford, California.. His temporary assignment to the Institute is greatly appi:~tl:ittd 'by the Division.

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Virology: Bacterial

The activities of the bacterial virus (phage) groups, headed by Professor Delbrlick, were at a higher level than during the preceding year, due to an increase of three new members: Doctor Dulbecco, who joined the regular staff as a Senior Research Fellow in September, 1949; Doctor Benzer, a post-doctoral Atmnic Energy Commission Fellow, who came 'in October, 1949; and Doctor Weidel, an 1nstitute Research Fellow, who came in April, 1949. Doctor Stent (Merck Fellow) and Doctor Wollman (Rockefeller Foundation Fellow) completed second-year renewals of :their Fellowships. In addition, Doctor Doermann, Doctor Luria and Mr. Watson visited for several months during the summer of 1949, and several others visited briefly in connection with the virus conference held at the Institute in March, 1950.

Stent and Wollman completed an important study of a rather mysterious phenomenon discovered by T. F. Anderson in.1945, viz: that certain phages need to be "activated" by interaction with an organic compound, the amino acid tryptophane, to enable them to attack their victim, a bacterium. What does this organic molecule do to the phage particle to alter so radically its biological properties? The molecule combines with the phage particle in a reversible manner but the kinetics of this reaction is extraordinarily complex. It seems that there are many sites on the surface of the phage particle, at each of which about five of these molecules can interact to form a very special complex, and it is these complexes which are responsible for the activity of the phage particle. It is believed that this situation, although so far without parallel in physiology, may well turn out to be of wide significance.

The most startling finding of the year was made by Weidel, who attempted, as had many others before him, to isolate the. "receptor spots" of the bacteria, i'.:e., the patches of surface structure on the bacteria to which a phage particle first hooks on when it attacks the bacterium. After many unsuccessful attempts to dis­sociate these "receptor spots" from the bacteria, Weidel tried the opposite tack, namely, that of dissolving and digesting away everything but the "receptor spots." When the material thus obtained was examined with the electron microscope (in collaboration with Doctor Baker of the University of Southern California), it looked' like exceedingly thin sausage casing; quite definitely it represents one layer of skin of bacteria. This material has very interesti?lg chemical properties different from anything previously described for bacterial skin layers. We hope that the availability of the materlial will greatly facilitate the study of the method of entry of the phage

·particles into the bacterium, and possibly also that of other viruses into their victims.

Doctor Weigle, Research Associate, made use of dark field microscopy to observe the lysis of infected bacterial cells and accompanying release of phage particles. This phenomenon is a spectacular sight to observe.

Mr. Bowen, Graduate Student, has begun investigations on photoreactivation of ultraviolet inactivated bacterial viruses. In this he is working with Dulbecco, whose primary research activity has been in connection with the mechanism of such photo­reactivation.

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Benzer has been studying the earliest stages of intracellular phage growth using changes of resistance to irradiation with ultraviolet light of the phage­bacterium complex as an index of the progress of intracellular development.

The virus conference held in March is described earlier in this report.

Mr. Siegel, Graduate Student working with Wildman, has investigated the proteins of normal cells of the bacterium E. ££!i and those of cells infected with phage. One of his purposes is to determine whether or not phage is formed at the expense of normal bacterial nucleoprotein, as tobacco mosaic virus appears to be in infected tobacco plants.

Mr. Clayton, Graduate Student in physics and doing his Ph. D. thesis problem with Delbrlick, is studying the action spectrum of phototaxis in Rhodospirillum rubrum under near-threshold, dark-adapted conditions, using monochromatic

• light of 1 00 A purity.

Working in collaboration with Singer {Chemistry Division)i Wildman and Miss Campbell, Research Assistant, made a study of the electrophoretic changes in leaf proteins in a number of plants, following virus infection. Iii the tobacco plant infected with mosaic virus, there appears within a few days after infection a new protein component characteristically different in electrophoretic mobility from any normal component. This new protein can be shown to be the tobacco mosaic virus. As virus protein increases in amount, a specific soluble leaf nucleoprotein decreases. For this and other reasons the virus protein is believed to be formed rather directly from the cytoplasmic nucleoprotein. The new virus protein component can be de­tected in the Tiselius electrophoresis apparatus before visible symptoms appear on the infected plant.

With a view toward using electrophoresis as a rapid method of diagnosing virus disease in plants, studies were made of cucumber mosaic virus in cucumber and water cress virus grown in Chinese cabbage. Both, like tobacco mosaic virus, are introduced into healthy plants through mechanically produced leaf wounds. ln both instances a characteristic new protein is detected electrophoretically before external syn1ptoms become evident. Finally, in Psorosis of citrus, a virus ti·:ans­mitted only through grafting, a new protein component can be detected by electrophoresis in infected leaves b'efore external symptoms are evident. These findings indicate that • the electro~horetic method might have important practical diagnostic value, particularly in cases such as quick decline of citrus in which the development of symptoms does not occur until many months after infection.

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In electrophoretic studies of tobacco mosaic virus, Wildman and coworkers have on several occasions observed that some 12 days after infection of a tobacco plant there appear two minor protein components, in addition to the major one known to be virus nucleoprotein. It is suspected that these minor components, not previously recognized, are of virus origin and it is planned to investigate their infectivity and other properties.

(See also section on Immunogenetics for seriological aspects of work on tobacco mosaic virus.)