We have whites!

Natalie Kim Bjorklund umbjork1 at cc.UManitoba.CA
Tue Feb 28 11:32:36 EST 1995

Upon arriving in our lab Monday morning and checking the spawnings, I 
noted several distinctly paler hatchlings in two of the five spawnings 
from our two male white mutant/wild type cross axolotls. Three of these 
are clearly white as they have no pigment at all except for gold colored 
eyes. I suspect that in a few days there will be serveral more obvious 
whites.  We should soon have breeding pairs of whites at the University 
Of Manitoba's small colony. Isn't genetics wonderful?

Thanks to the following who answered my query, 
Jonathan Slack, John Armstrong, Susan Duhon, Giselle Thibaudeau, Roy 
Tassava, and Steven C. Smith,
I have taken the liberty of producing an amalgam of the answers for the 
information of anyone else out there who doesn't know about the 
identification of white mutants:

The black females will produce pigment in the eggs so they will have to
develop to swimming larvae before the maternal pigment breaks down.
Before this stage, there are no pigment cells, so all embryos will be the
same (brownish) colour, from the maternal pigment. 
The white mutant is supposed to be a defect in pigment cell migration, so 
the initial pigmentation is normal. However, the ectoderm doesn't support 
neural crest cell migration. So, if you check under a microscope, you can 
detect them at stages 35 and later. The pigment cells will not appear on 
the flank as they do in wild-types.
At hatching time the melanophores are fewer in number and more punctate, 
staying close to the dorsal midline instead of being distributed 
throughout the body as in wildtype animals.  Soon after hatching 
even these melanophores disappear in the white animals. By about 
hatching until after the larvae have been feeding for a week or 
two the whites should be noticably paler.  Placing the bowls on 
a dark background for a while will enhance the difference. 
It is a well behaved gene and a clever mutation.

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