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Underwhite - The Singapore Connection.

mainuwimg.jpgAround 2006, a Singapore breeder, Joeyvoen Teo, asked for some help in identifying their strange pastel coloured gerbils.  At the time she was very confused, as many of the pastel coloured offspring looked similar to Ruby-Eyed Whites, White bellied Creams and Self Creams(syn. C-separator/resn).  With having so many of the Ruby-Eyed Whites and White-Bellied Creams appearing in the litters, she assumed that eventually she would see Slates or Grey Agoutis appearing in the litters too.  None ever appeared.

In those early days, I advised test crossing to get an idea of what recessive colour genes were at work.  Initially out crossing to ‘ee’ coat variants to see if the self cream coloured gerbils were carrying Extension of Yellow and secondly to test for uw(d) .  Two self creams were used, one being out crossed to a Nutmeg, the other to a collared Slate (?).  However although the test breeding identified Extension of Yellow, in all of the crosses undertaken, not just these, but in all further crosses as well, there was never any trace of uw(d) appearing.  We did hope that somewhere in Singapore that a Slate or a Grey Agouti would appear to confirm the presence of uw(d) in Joey’s kennel, but the closest colour available were Ruby-Eyed White phenotypes, which she presumed carried uw(d).  Crosses to this colour never produced any recognisable uw(d) coat varieties, just more  pastel shades.

It seemed there was no concrete way of proving that uw(d) was present in Joey’s kennel.  Joey gave names to these unusual pastel shades.  The ones identified as white bellied with very slight ticking and extremely dark, almost liver coloured eyes were called “Silver Ash” and the darker self creams with similarly coloured eyes were entitled “Ash”.  Other strange pastel shades resembling a beige/dove shade which when adult, moulted to a cream colour were also apparent in some litters.  This particular shade resembled no known coat colour variety at the time.

According to Joey, gerbils first came to Singapore in 1988 and were imported from the UK. They were mostly Agouti and Argente. There was also a report that Burmese/Siamese gerbils had been imported at a later date, but these had a low survival rate and eventually died out.  However, it may have been bred often enough to leave the Himalayan gene circulating in the Singapore gene pool, albeit at a low frequency at that time and this would explain some of the shade differences in many of her pastel coloured pups. Even so, with the high temperatures present in Singapore it would make it extremely hard to identify any Himalayans.

Another point to remember and one that would hamper anyone’s breeding programme, is that light/white coats with red/pink eyes are extremely unpopular and hard to re-home in Singapore, as anything with light coats and red eyes are basically looked down upon as being “rats” or rat-like in appearance.

Unfortunately, Joey left Singapore for the US, so the mystery was never fully solved.  Before leaving the country she gave 24 gerbils to the Singapore Zoo and these included all the coat colours that had been bred, including the Ash’s and Silver Ash’s. She also gave 2 mottled gerbils that presumably carried this gene to Shana / Farsha Gerbil Clan, who unfortunately (according to Joey) declared them both unfit for breeding. If they had been bred, no doubt they would have had these pastel coat colours appearing in their kennel.

Joey also passed a “REW” to Taro, a Malaysian breeder, who at the time wanted to introduce REW and Slates in to their country. However, when crossed to a Black, supposedly carrying uw(d) the only colours appearing in litters were Agouti and Black, so maybe the gene has now migrated there too, or maybe not.

In late 2007, Michelle Inman also came to me asking for advice on her strange pastel shades.  However, Michelle had gone one step further than Joey and through various crosses realised that the strange gene she discovered was allelic to our G locus (now known as Underwhite).  We confirmed this by repeating her crosses using a breeding method known as a complementation test.  Michelle had done a great deal of test breeding on this gene and documented all her crosses, which made it much easier for me to assess her breeding. 

I drew up a short list of genes for Michelle, all of which could be responsible for these colours, but until we figured out what gene our Grey Agouti was, everything was just guess work.  On that short list was Underwhite, but information on this gene was very sparse and all breeding done by the scientific community was undertaken on non-agouti (black).  After several months of searching though reports, I came across Silver’s report  on uw(d) and uw(dbr) (W.K. Silvers et al., 2000). Two known alleles of the Underwhite locus.  This was a breakthrough for me as it was the first time that breeding data on Agouti was ever documented.  In the paper it described the phenotype of Underwhite Dense on an Agouti genetic background as mimicking the Chinchilla gene.  Finally we had the confirmation needed which proved our Grey Agouti coat colour was in fact the underwhite dense allele and the mystery of the locus was finally solved, and its true identity was revealed.

Joey and Michelle corresponded and Michelle helped Joey go through her own breeding data.  It was highly likely that that the gene in Singapore was also Underwhite, but it will be a good while yet before it can be proven.

The big problem for both breeders is that not only is Underwhite a phenotype mimicking gene, it is also a masking gene.  As such, it resembles other known coat colours, but also has the ability to mask black-eyed gerbils to make them ruby-eyed instead.

Phenotype Mimics and Masking Genes.

Until the Underwhite gene appeared on the scene, we only had two genes that could be labelled as phenotype mimics and these presented no real problems to a gerbil breeder.  These are our Grey Agouti, and Extension of Yellow.

While not especially pertinent now, the Grey Agouti closely mimics the Chinchilla gene and if the Chinchilla gene emerged it would present distinct and obvious problems.  The same can be said for Extension of Yellow if Dominant and/or Viable Yellow genes should appear in the Mongolian gerbil.

Imagine how hard it would be to identify all our ‘e’ and ‘e(f)’ coat colour varieties if a gene appeared that could mimic all the known colours that we associate with the Extension of Yellow gene!

With the appearance of the Underwhite gene it now becomes a different story and a realisation that the entire Underwhite locus is capable of mimickry.

Not only have we got in circulation 3 cream variants, 2 white bellied creams and one self cream, all being created by combining uw(d) with existing genes, we can now add to that the 'uw' gene which can create these coat colours in a single stroke on both 'A-' and 'aa' backgrounds and has the ability to combine with ‘ee’ and ‘c(chm)c(chm)’ & 'c(h)c(h)', to creat red-eyed white coat colours. So unless we know the pedigree of our gerbils intimately, breeders will be having real big trouble identifying red-eyed cream variants where some can be genetically black-eyed but are showing ruby eyes instead and many litters will have the potential to be dominated by red-eyed white coat phenotypes.   These are the same problems when identifying coat colours that both Joey and Michelle quickly encountered when initially working with this gene.  Let’s add to that the fact that it has the ability to lighten some black based colours too and we have a recipe for a big problem on our hands if this gene ran unchecked in the gerbil gene pool.

Underwhite is also a masking gene and as such will mask the presence of any other genes present. Again this creates a big problem to breeders, especially if it is a recessive gene and as such can easily get into your breeding stock without your knowledge.  If this were the case, then within a few generations the gene has the potential to seriously mess up any breeding line. I don’t think any breeder of any colour (unless you know any breeders out there who concentrate on pew/rew varieties) that will be happy about having so many red-eyed white gerbils suddenly appearing in their litters when they had so studiously avoided having pew/rew’s in their breeding lines in the first place.

The fact that Underwhite can swamp or over run our known Grey variants, especially if they are carrying 'c(chm)', 'c(h)' or 'e' to an extent that the major percentage of litters will consist of  high amounts of pastel shades, then presents a problem when the present trend of gerbil breeders have a distinct affinity of crossing new genes into every existing coat colour available.  If carriers of the gene go to pet shops, or are sold unwittingly to other breeders, then it won’t be long before many of our familiar grey variants become rarities in litters and a large portion expected are then replaced by pastel shades.

We are now seeing this problem emerging in Singapore.  Although the Grey Agouti is known to be there, and reports of it go back prior to 2005, it remains a distinct rarity.  Instead, where REW/PEW's  were once relatively uncommon and unwanted around 2004-5; mainly due to them being hard to re-home and looked upon by many people as "lab rats", white gerbils with red eyes are now amongst the main colours being produced in the country despite the fact that uw(d) is extremely rare and c(chm) (a gene commonly combined with 'p' to produce pink-eyed whites) didn't exist there at all.  The problem of red-eyed white gerbils may be increased again now that a recent import of c(chm) from the USA has been recently reported.

Michelle recently asked 5 important questions to the gerbil community. These were;

  • Do You understand this gene?
  • Why do you want it?
  • What would you do with it? Why?
  • Breeding plans
  • Offspring that will inevitably occur

The point to these questions should be quite obvious after reading the above.  You could even consider them as “screening” questions, especially so if you were considering people to carry on breeding the gene.  As the founder of the gene it’s important to ask questions when considering the release of the gene to the gerbil community and into the gerbil gene pool.  If you had discovered a new gene and also realised from your own breeding studies that when released the gene has the capability of polluting our current gerbil gene pool, wouldn’t you ask these questions as well?  Wouldn’t you want to be assured that other breeders understood the gene and knew how it worked?  Wouldn’t you want to make sure that fellow breeders wouldn’t ruin their own and other peoples breeding lines if they subsequently and intentionally acquired this gene?

However, it was very clear from the answers given, that few, if any breeders understood the genes full implications and some couldn’t even understand why the questions were being asked in the first place.  With free trade existing between Singapore and the US, inevitably this gene will hit there before Continental Europe, even if Michelle doesn’t release it.  Especially so, as some breeders seem very keen to get their hands on it, which is understandable with any new gene.  Because the US is so vast, it will be a good while before the gene becomes problematic.  However, when exchanging it between small sections of the gerbil community there and knowing there’s always been a trend for a lot of breeders to use gerbils with a lot of recessive colour genes as breeding animals, (because it’s a lot easier to re-home rainbow coloured litters), then the problems of identification and swamping litters with pastel shades will become quickly apparent if some care and understanding isn’t taken with this gene.