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The "C-Locus" part 1

Updated: Jun 16, 2021

GENETICS POST #wcrgenetics "C-LOCUS, pt. 1"

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TERMINOLOGY & DEFINITIONS [ Heterozygous ] - refers to different inherited forms of a gene on one particular allele [ Homozygous ] - refers to identical inherited forms of a gene on one particular allele [ Dominant ] - a dominant gene is a particular variant of a gene, which for a variety of reasons, expresses itself more strongly all by itself than any other version of the gene on a particular allele. [ Recessive ] - a recessive gene is a gene whose effects are masked in the presence of a dominant gene. [ Allele ] - one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome. [ Locus ] - a particular position, point, or place. [ Punnett Square ] - a square diagram that is composed of a grid of usually four boxes and is used to calculate and depict all the combinations and frequencies of the different genotypes and phenotypes among the offspring of a cross or breeding event.

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** C - LOCUS - ALBINO

The C-locus genetics post will be multiple parts. The C-locus is the Albino locus. There are multiple alleles on this locus, which is why it must be broken up to multiple parts. In this part, I will cover the basic genetics behind CC/Cc/cc which is full colour and Albino.

"C causes the dilution of both yellow and black pigment but each is affected differently. There are three known and a forth suspected allele at this locus. Yellow pigment is completely eliminated by the third one, but black pigment shows a more gradual reduction, not being completely eliminated until the fourth allele." [https://www.afrma.org/ratgenpart1.htm]

Full colour is denoted by a capital "C" and albinism is denoted by a lowercase "c."

A rat with the genetic code "Cc" will display full colour but is heterozygous for albino. This rat will display simply as the base/any dilutes with no hints of albinism. A rat with the genetic code "cc" is fully diluted, which displays as a completely white animal with pink eyes. Albino rats can be and carry other colours, too, but there's no visual clues to this as the albinism fully dilutes both yellow [pheomelanin] and black [eumelanin]. A rat that is albino looks identical whether it is Agouti or black based.

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CALCULATIONS USING PUNNETT SQUARES Example rat in this instance is BLACK based. You can replace "aa" with "Aa/AA" and have the same results, except Agouti based.

aa cc x aa cc = aa cc (100%) aa cc x aa CC = aa Cc (100%) aa cc x aa Cc = aa cc (50%) / aa Cc (50%) aa Cc x aa Cc = aa cc (25%) / aa Cc (50%) / aa CC (25%) aa Cc x aa CC = aa Cc (50%) / aa CC (50%)

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aa CC = Full colour [black] aa Cc = Full colour het for albino [black carrying albino] aa cc = Albino

@UnitedRodentCommunity

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PHOTO CREDS Viktor Cobb at Dandelion Critters Jaymie Winstead at Maineiac Mischief Rattery Daema Scarlette at Maelstrom Rattery Thank you for sharing your images with me!

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