DNA Microarray TechnologyUnder the guidance of

Dr .Manjunath

Ankitha Hirematha3rd sem, MSc.,

Dept. of BiotechnologyKuvempu university.

CONTENTS

• Introduction• Historical Background• Principle• Overview steps• Preparation of slide• Microarray scanning• Data analysis and normalization

DNA Microarray Technology

Why ?

To analyze the expression of thousands of genes in single reaction, very quickly and in an efficient manner.

To understand the genetic causes for the abnormal functioning of the human body.

To understand which genes are active and which genes are inactive in different cell types.

What is DNA Microarray Technology ?

It is “an orderly arrangement of thousands of identified sequenced genes printed on an impermeable solid support , usually glass, silicon chips or nylon membrane”.

DNA microarray chips are also known as DNA chips, DNA arrays, or biochips.

Historical background :

• Southern blotting was developed in the year 1975.

Sir Edwin Southern

• The concept of DNA microarrays began in the mid 1980s.

• Pin based robotic system was developed by Lehrach’s group in 1990.

•“Quantitative Monitoring of Gene Expression Patterns with a complementary DNA microarray” reported by Patrick Brown, Mark Schena and colleagues in Science (1995).

• Steve Fodor developed scanner for reading the output.

Sir Steve Fodor

Sir Patrick Brown

•Mark Schena was proclaimed as the “Father of Microarray Technology”.

Mark Schena

Principle of DNA Microarray:

An overview of steps involved in DNA Microarray

Preparation of DNA Microarray Slide :

The solid supports used are glass, silicon or nylon membranes

Length of slide is 25 X75mm

Within the area of 3.6cm2 , 10,000 to 20,000 spots(genes)

Diameter of spot is 50-150μm

Distance between the spots is 200-250 μm.

Fabrication

• Photolithography• Robot spotting• Inkjet

Photolithography

Robot Spotting

Inkjet spotting

Performing DNA Microarray Experiment

Eg. Saccharomyces cerevisiae

O2 O2

Centrifuge

Supernatant is discarded

Add extraction buffer

Remove that buffer containing mRNA and place in fresh tube

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Reverse Transcription

TTTTTTTTTTTTT

TTTTTTTTTTTTT

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TTTTTTTTTTTTT

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c DNA

Mix

GATC

GATC

GATC

ATGC

ATGC

ATGC

TCAG

TCAG

TCAG

SCANNED

When green laser comes,

When red laser comes,

Merged image :

DNA Microarray Scanner

• Fluorescent intensity is measured

Data analysis and normalization

“Normalization means to adjust the microarray data for effects which arise from variation in the technology”.

Applications

• Gene expresion profiling, SNP detection, human diseases etc..

• IPSC (Induced Pleuripotent Stem Cell) cell lines are validated and monitored.

• Toxic studies

CONCLUSION

Since this DNA microarray technology is used for the analysis of expression of thousands of genes at once, and has wide applications in in analyzing various diseases. It is one of the smartest technique.

•Tim Lenoir ,Eric Giannella (2006) The emergence and diffusion of DNA microarray technology. Journal of Biomedical Discovery and Collaboration(JBDC). 1:11 

•Samuel K. Moore (2001) Biochips are now a critical tool for analyzing the human genome--and a lucrative product attracting technology giants. IEEE spectrum• http://www.premierbiosoft.com/tech_notes/microarray.html

•http://www.genome.gov/10000533

•http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1590052/

•http://www.medscape.com/viewarticle/543871_2

•http://en.wikipedia.org/wiki/DNA_microarray#History

•http://grf.lshtm.ac.uk/microarrayoverview.htm#m1

•http://www.ncbi.nlm.nih.gov/About/primer/microarrays.html

•http://www.digizyme.com/portfolio/microarraysfab/photolith.html

REFERENCES

Thank You