Genetic analysis of the modifier for the Hooded phenotype in rats

Kathrin Guttmann Knowledge, markings, Breeding & Genetic

The gene, that is largely responsible for the subscription of color rats, is at the H locus on chromosome 14 in the region of the KIT gene, the many animal species spotting (Piepaldism) can cause.

What makes the H locus relative to other loci, which are responsible for the coat color, the color Rat, is, that there are not only two alleles, which can occupy this locus. In addition to the dominant H, the a continuous dyeing without white markings (so-called self-drawing) expresses, and the recessive h, which causes Hooded-drawing in the case homozygous (Colored head, neck, chest, Shoulders and a wider, uniform thickness strip across the back to tail), there are other alleles:

  • hi Hooded Irish
  • hn Hooded notched
  • he Hooded extreme
  • Hre Hooded restricted

All this allele are on the same locus and behave in the most combinations codominant. That means, that the different alleles equally strong effect on the phenotype in a heterozygous animal. Both alleles are thereby fully expressed. That means, that the different combinations of two of the alleles H, h, hi , hn ,he and Hre results in different patterns. Deviating from the wild form of co-dominant inheritance is H (no drawing) dominant over all other alleles and h is recessive to hi . In addition, the restricted allele homozygous lethal.

The amount of color, which is expressed by these alleles, behaves as follows (of a lot of color and low amount of white to little color and high percentage of white): H> hi > h > hn >he > Hre

It is not here - as initially Castle (1914) accepted- um Edit, influence from another locus, the expression of the gene Hooded, All but independent on the H-locus in the sense of a polymorphism. the idea, that one or more Modifier a gene locus on the H- "befallen" (either the dominant or recessive H h) is wrong (see illustration on, since it is the alleles themselves, lying on this locus.

Furthermore, it is believed, that the inheritance of a variant of the Husky drawing (English "Roan", is also known as "Essex" designated) runs through the H locus. caused them to through the roan allele hro or Hro , where there are different specifications to, whether this allele dominant and homozygous lethal case (NFRS) or incompletely recessive (test breeding) is. When looking at the genetics of Huskies need to distinguish between European and US animals, as they probably have a different genetics (Curiosity Rats). So an independent locus for encoding a dominant-recessive inheritance Husky is also discussed.

In addition to the H-locus, there is at least one other locus, actually influenced in the form of a modifier, the expression of alleles at the locus H. On the locus alleles Hm Hm cans (short back drawing) and Hml (long dorsal drawing) lie. Taken alone, these alleles can exacerbate no drawing phenotypically, but affect the expression of all on the H-locus.

result from the preceding considerations, a variety of combinations, the partially similar looking phenotypes may result in different genotypes and they often do not follow a Mendelian genetics.

Possible allele combinations for certain drawings are listed below:

Bareback hh or hhe or Hःms or hhi
Berkshire Hh or hhe or hihi or hihn
Blazed many possible combinations
Capped hnhn
Capped Stripe hreh or Hrehre (lethal?)
English Irish Hh or Hhi
Hooded hh or hml
Irish Hh or Hhi
Masked hehe
Variegated ?

Rule of thumb for the inheritance of drawings

With regard to the inheritance and phenotypic expression of Hooded alleles and modifier provides the AFRMA the following rule of thumb.

It takes the following levels:

  1. Self
  2. English Irish (Spot on the chest)
  3. American Irish (Spot on the belly) and Berkshire
  4. Hooded, Variegated und Bareback
  5. Masked, Leaning head drawings and Black Eyed White (or. Pink Eyed White and Red Eyed White at corresponding other primary colors)

Rats drawings the same plane can create all the drawings of this plane and a level.

Rats from directly successive level (also z.B. level 1 With 2, level 2 With 3 etc.) can produce the drawings, corresponding to these two planes.

rats, whose planes are separated by a plane (also z.B. level 1 With 3, level 2 With 4 etc.) especially drawings of the intermediate level will produce (also z.B. at level 1 With 3 the level of 2), but also a small number of offspring of their own level (also z.B. at level 1 With 3 the level of 1 and 3).

rats, whose planes are separated by two or more levels (so level 1 With 4, level 1 With 5 and level 2 With 5) progeny are drawings with the intermediate levels (also z.B. at level 1 With 4 the levels of 2 and 3), but not create their own levels.

Please note: is a rough rule of thumb, not to secure genetic findings!

Different characteristics of the different alleles Hooded. Those: Castle (1914).

Capped bzw. Notched Ratte. genotype: hnhn. Those: Castle (1914)

Hooded Ratte. genotype: hh or hml.Those: Castle (1914)

Irish Ratte. genotype: Hh or Hhi. Those: Castle (1914)

Verpaarungsexperiment. A ruddy rat (8000) comes with a Black Hooded (6176) mated. 8021 and 8018 are from the F1. In the following generation, the features columns on partially. 8075 is a Black Hooded mismarked, 8076 and 8077 are Berkshires, 8078 is an Irish. Those: Castle (1914)

Verpaarungsexperiment. Those: Castle (1914)