Biotechnology - Inheritance and Breeding
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Transcript of 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.