🚀 go-pugleaf

Recent new information regarding the difference between the colour we call
"Mink" in Australian domestic rats and the Mink in Europe and the US has
prompted quite a bit of reading and research regarding both the liklihood of new
mutations of colour and the protocols for naming new colour and pattern
genotypes.

The point of all this reading is to try and understand genetic notation in other
animals, so that new colours (like the Australian mink turning out to be
different from European mink) can be identified and denoted in a manner which is
logical, consistent with notation of colour and pattern already existing in rats
and consistent with research and information on notation of genotypes in other
animals.

For instance:  Roan.  Anyone who's ever had anything to do with horses will
immediately recognise the name roan as being significant of coloured hair in a
coat interspersed with white hair.  Likewise Greying, in dogs, cats and horses
this is either in localised areas or over larger areas of the animal, and
becomes gradually more grey throughout the animal's lifetime.

Although Greying in dogs is slightly different to greying in horses, the name
and effect of the mutation causing this colouring is quite similar and reference
to it will be understood by dog, cat and horse owners.  People who come to own
horses after owning dogs will be familiar with Greying when they hear the term
used.

Naming colour influencing genes is generally done by giving the genotype a
letter indicating the colour or effect of the gene, so we have black denoted as
B, D for dilution of colour, A for agouti and so forth.  The naming is important
since we have the Australian mink to name, since it has been apparently
identified as being different to the minks found in Europe and the US. (Sue I'm
waiting for info on the test breeding so I can include reference in our
standards :-) )

Since Australian mink is apparently quite a bit more blue or grey than European
mink, I would like to suggest (m^b (^b indicates the b to be superscript)) as
the notation for Australian mink.  There are two reasons for this.

As stated, the Australian mink is apparently more blue than European or US mink,
hence the use of (^b) as "blue" mink.

It is much more likely that a colour effecting mutation would occur on a locus
already known to affect colour by more than one mutation, rather than on a
completely different locus.  It is logical then that the three different minks,
European, US and now Australian, are all different mutations on the M, mink,
locus rather than the Australian mink occurring on a completely new locus.

Thus the proposal of (m^b) for notation of the Australian mink.

Then there's blue.  The effect of the dilution gene has only recently been
discovered in Australian rats, but the phenotype is consistent with that found
in dd rats overseas, and dd in other animals.  Whether or not the blue rats in
Australia turn out to be identical with those in Europe or the US, it is much
more likely that a new mutation causing a blue colour would occur on a locus
known for at least two previous colour effecting mutations (dd and d^rd^r (blue
and "russian" blue)) than on an entirely different locus previously unknown for
colour effecting mutation.  In the absence of molecular analysis or test
breeding with blue rats from other countries, it would seem logical, for the
time being, to denote the blue rats in Australia as aadd, a standard notation
for a blue coat in just about every mammal bred for colour.

Back to grey.  In recent years in the US, a lighter blue mutation has occured.
Some breeders have denoted this as aagg.  I have been unable to find anything to
indicate that the light blue is anything other than a different blue.  It
certainly doesn't sound like the effect of the G gene as described in any other
mammal.  Hence, it would seem more logical, in the absence of molecular analysis
or test breeding which would show this light blue to be a mutation on a
completely different locus, to consider this light grey-blue to be another
mutation on a locus already known for at least two different colour affecting
mutations.

The husky rat.

If husky in rats begins with dark colouring in some parts of the coat, and
silvering gradually spreads through the coloured areas to produce the faded coat
colouring in the standard areas described by the 'pattern', on initial reading
of husky standards and their comparison to the effects of the G locus mutations
in cats, horses and dogs, one starts to wonder if perhaps the G locus should not
have been reserved for the same reference in rats as in all the other mammals,
just as W and E are widely understood in other mammals, hence no denotation of W
or E have yet been made in fancy rats.

The idea of light blue rats being aagg has been fairly widely accepted in the
US, but again, there doesn't seem to be any reason for it being denoted as a
separate locus, apart from the concept that someone thought it looked like a
light blue-grey.

If a husky rat has a phenotype which is produced only by white marking, then
given the highly unstable nature of the H locus which produces most of the other
patterns in rats, we could look more closely at a cause there.  While there is
nothing to say that the husky phenotype might not be cuased by the effects of
several genes, including a mutation on the H locus, patterns on a rat are easily
predicted by skin colouring from virtually the time of birth, and the pigment
remains in the skin throughout the animals' lives.  The development of more and
more greying or roaning in the patterned areas of the husky rat indicate that
the H locus on its own is not the most likely cause.

In light of this, I would like to propose that the light blue colour be
considered for notation as (d^ld^l).  

In summary: Study of the genetics of colour and pattern in domesticated Fancy
rats in Australia is still fairly young.  Many of the markings and colours are
quite easily identifiable, for example the agouti and hooded phenotypes, hence
we can confidently assume to use the same notation for the genotypes causing
these effects as used overseas: Agouti (A/-) and Hooded (hh).  When it comes to
new mutations affecting the phenotype of colour and patterns which may be
relevant to the colour and pattern standards described here, it would appear
sensible at the very least, to further study the effects of different colour and
pattern affecting mutations as denoted in other animals, so that we can benefit
from the experience and research done on those animals and also name new
mutations in a manner which will be more readily understood by both rat owners
and researchers of genetics and phenotypes.  The jury is still out as to whether
the husky rat is a colour or a pattern, and in the absence of any apparently
husky rats here to test breed to silvered or marked animals, the proposition of
notation for the husky phenotype remains one for discussion.

http://bowlingsite.mcf.com/Genetics/Genrefs.html  
http://www.vgl.ucdavis.edu/~lvmillon/coatclr.html
http://www.people.fas.harvard.edu/~brown/dogs/genetics/color-genetics.htm
http://www.fanciers.com/other-faqs/color-genetics.html
http://www.rodentfancy.com/rmfe/husky.shtml
http://www.bubblegunners.org/hawthorn/varieties.html
http://www.miceandrats.com/standrat.htm
http://members.dingoblue.net.au/~farrall/bruce/index.html

Ana Farrall 


Remember the last time you were sane and well rested,
and act like that.
farrall at dingoblue dot net dot au
http://members.dingoblue.net.au/~farrall