biotechnology - inheritance and breeding

Hamster GeneticsHamster Genetics

Biotechnology –Biotechnology –

Inheritance and Inheritance and GeneticsGenetics

ApplicationsApplications

Standards Addressed:Standards Addressed:15.0 Animal Growth and Production

15.3 Reproduction

15.4 Biotechnology –

16.0 Using Scientific Processes to Analyze Data

16.1 Scientific Method

16.2, 16.3, 16.4 Scientific Research

16.6, 16.8 Communicating Results

17.0 Relationships Within Living Systems

17.2 Heredity

18.0 Bioethical Issues

18.3 Animal production

Objectives:Objectives:In a Laboratory Environment Students will be able to:

1- Use the scientific method to hypothesize, predict implement and report conclusions

2 – Illustrate patterns of inheritance using the principles of Mendel’s genetic theory

3 – Demonstrate respectful, and appropriate treatment of lab animals

Process:Process:Using Syrian Hamsters students Using Syrian Hamsters students will identify phenotype of animal.will identify phenotype of animal.

Through multi generation Through multi generation breeding the genotype will be breeding the genotype will be determineddetermined

As genotype becomes As genotype becomes established, predictions regarding established, predictions regarding future generations are made, future generations are made, tested, and results reportedtested, and results reported

Why Use Syrian Why Use Syrian Hamsters?Hamsters?

1 – A friendly, affordable, easily available animal

2 – Rapid maturation of pups

3 – Easily bred – short estrous cycle – 4 days

4 – Gestation period 16 days

5 – Established coat color, coat type, and coat markings

4 – Monohybrid and dihybrid crosses visible

Careful, monitored Careful, monitored breeding will result in breeding will result in pedigree chartspedigree charts

Genetic Predicting Helps Determine Future Offspring

Safe, humane lab animal care is basic

Basic Genetic Information:Basic Genetic Information:

Hamsters have 44 Hamsters have 44 chromosomeschromosomes

Ovaries carry 21 Ovaries carry 21 autosomes and an Xautosomes and an X gametegamete

Sperm carry 21 Sperm carry 21 autosomesautosomes and an X and an X oror Y gamete Y gamete

Syrian hamster Karyotype courtesy of Knud Christensen, Ph.D., The Royal Veterinary Agricultural University, Denmark

Step 1: figure out the hamster's phenotype, and write a preliminary genotype.  A few quick examples. ("_" stands for "unknown.")

Banded Longhair Red Eyed Cream Ba_eellpp Satin Cinnamon Tortoiseshell ppSasaToto Dominant Spot Yellow Black male aaDsdsToY Rex Smoke Pearl female dgdgrxrxToTo Chocolate (Sable) Roan bbeeU_ Whwh Recessive Dappled Umbrous Golden rdrdU_

Expanding the Genotype

More information about the hamster's genotype can be gathered by looking at its parents, siblings and offspring

Breeding an animal can provide more data about its genetic make-up.  

It is especially useful as a tool to confirm suspicions of heterozygosity.  

For any trait that may be heterozygous, breed to an animal that is homozygous recessive.

Appropriate breeding can help sort out confusing colors.

For example this helps with the Greys, especially if the Grey is in combination (for instance, in the Grey Sables or Black Eyed Ivories).  

Breeding to any hamster without grey in its pedigree will give a good indication of the genotype.

There are There are eleven eleven basic colors basic colors in Syrians.in Syrians.  

Ten (excluding Golden, which is the “wild type”) are determined by a single gene pair.

It can be hard to It can be hard to determine color because determine color because

coat types and coat coat types and coat patterns also influence patterns also influence

appearance.appearance.

Golden – wild color combination – where it all started

“Ticking” of coat

And, the fur is often different close to the skin, from what is seen on top -

Determining the Determining the Coat Color Coat Color PhenotypePhenotype

Color Genotype DescriptionGolden ++ Rich dark mahogany heavy black ticking OR

Light fawny gold

Golden is the agouti, or wild code. It must carry all color genes possible, so would look like this: AA BB baba CC DgDg dsds EE FdFd LL lglg PP RdRd RuRu RxRx SS sasa sgsg toto uu whwh

Color Genotype Description

Black aa Jet black to the roots

Black Eye ee Deep sandy cream Cream to the roots

Color Genotype Description

Color Genotype Description

Cinnamon pp Rich russet orange

Color Genotype Description

Dark Ear cdcd White to the roots White

Color Genotype Description

Extreme cece Creamy grey with Dilute black ticking

Color Genotype DescriptionDark Grey dgdg Pearly grey, black

ticking, black eye rings

Color Genotype Description

Light Grey Lglg Buttermilk grey dark ticking

Color Genotype Description

Rust bb orange brown ticked with

brown

Color Genotype Description

Silver Grey SgSg Soft pastel grey ticked brownish black

Color Genotype Description

Yellow ToTo or ToY Dusky yellow with heavy black ticking

Color Tortoiseshell (females only)

TotoBaba, TotoBaBa, or TotoDsds

sex-linked bi-colored or tricolor animal - a balanced pattern of colored, yellow and white patches (sometimes black)

Genotype

Description

Coat TypeCoat Type

Another gene we will select for -

5 Coat types exist -

Shorthair ++ Wild type coat – short, even dense

Longhair ll Longer hair over top, excluding face,

much greater in males, not as much ticking

Rex rxrx Wavy, frizzy, diluted color, curly whiskers

Satin Sasa Glossy sheen, shiny

Hairless hrhr No fur, may have curly whiskers

Fur PatternsFur Patterns

8 Specific fur pattern types exist8 Specific fur pattern types exist

Banded BaBa Centrally placed band of white (1/3 of body) white belly

Dominant Spot Dsds White with colored spots, white face blaze, white belly

Recessive Dappled rdrd

Description: White with colored face, rear brindled splotches, shoulders white, white face blaze, white belly

Roan Whwh White with colored hairs ticked through coat, more color on head, white belly

White Bellied WhWh white ticking, especially on face

Piebald ss Similar to dominant spot, but has colored

patches also on belly

Color Tortoiseshell (females only)

TotoBaba, TotoBaBa, or TotoDsds

sex-linked bi-colored or tricolor animal - a balanced pattern of colored, yellow and white patches (sometimes black)

Genotype

Description

The yellow patches in Tortoiseshell are modified according to base color – Cinnamon becomes honey – Dark Grey becomes pearl – Lilac becomes lilac pearl

Remember – this is a sex linked trait – only in females!

There are two main breeding techniques - selection and crossing.  

Selection is the careful choosing of individuals for mating, allowing only the best to become parents of the next generation.

Crossing, is the pairing of the selected individuals so that the best offspring possible can be produced.

Inbreeding involves crosses of first degree relatives.  

This is done to concentrate desirable genes.  

Unfortunately, it will also concentrate undesirable genes so it must be accompanied by rigorous selection and care.

Backcross (offspring bred to one of its parents) Do with care and only 1 generation

Sibling cross (brother bred to sister – the most unsafe – only unusual circumstances (verify genetics_

Linebreeding is the pairing of more distantly related animals.

Cousin to cousin – Aunt to nephew, uncle to niece -considered fairly safe

Outcrossing is the breeding of totally unrelated animals. Done when 2 exceptional, unrelated animals exist. Very safe.

Lethality

Lethal genes result in death in utero or Shortly after birth.  

Lg (Light, or Lethal, Grey) and Ds (Dominant Spot) are lethal in homozygotes.  

In a monohybrid cross (e.g., Lglg x Lglg) 1/4 of the embryos are likely to be homozygous dominant and will not survive.  The litter is then three fourths as large as it would have been and has the remaining genotype (and phenotype) ratio of 2:1.  

Since the surviving hamsters are healthy, the only disadvantage of these matings is smaller litters.

Mating two hamsters that are Roan or White Bellied (both Whwh) gives litters in which 1/4 of the babies

can be expected to be Eyeless Whites (WhWh).

Eyeless Whites typically have a shortened

lifespan of six to twelve months.

Principles:Principles:

Careful Breeding Careful Breeding Results Results

In Superior Animals!In Superior Animals!

Breed for Fun, Breed for Fun, Knowledge, and Knowledge, and Improved Species.Improved Species.

Produced for:

Santa Rita High School Agriscience Program

By:

Catherine Patterson, Instructor

Special Thanks To:

River Road Hamstry and the many owners and breeders of Hamsters who placed information on the web.