Description:
Black-at-Hatch is a gene in coturnix quail that, in heterozygous form, causes the bird to have partial black back as a chick that molts into a slightly darker shade of brown as the chick feathers out. In homozygous form, the gene is lethal, causing the bird to hemorrhage in the embryo after about 4-9 days (1) and fail to fully develop. Preliminary studies have shown that if the homozygous black-at-hatch could survive, they would have the typical brown featheration (2). It was first documented in 1977, and been common since.
This mutation has been studied particularly well due to the liver and capillary issues that the homozygous embryos have (1), as they have been used as a test subject for different medical treatments. It also serves as an important marker site for advanced genetic linkage (3), meaning that because the gene is mapped so thoroughly, it can be used to help figure out the locus of other genes. It also is a good marker for overall eumelanin and black pigmentation in chicks (4).
It is not currently believed to be in public hands at this time, but is alive in university labs and does still exist and is being tested on.
The shorthand for Black at Hatch locus is Bh, and the order of dominance is Black at Hatch > Pharaoh.
Breeding with Black at Hatch:
Note: birds labelled with black at hatch are heterozygous, anything homozygous can't exist outside of the egg and has been labelled as "dead".
Black at Hatch x Black at Hatch = 25% Wildtype, 50% Black at Hatch, 25% Dead
(Bh / bh+ = 25% bh+/bh+, 50% Bh/bh+, 25% Bh/Bh)
Black at Hatch x Wildtype = 50% Black at Hatch, 50% Wildtype
(Bh/bh+ x bh+/bh+ = 50% Bh/bh+, 50% bh+/bh+).
References & Further Reading
ONO, Tamao, and Noboru WAKASUGI. "Abnormalities in liver morphogenesis attributed to the Bh (black at hatch) lethal gene in the Japanese quail." Japanese poultry science 20.3 (1983): 158-169.
Kubota, Yukihiko, et al. "Bh (black at hatch) gene appears to cause whole‐body hemorrhage in homozygous embryos of Japanese quail (Coturnix coturnix japonica)." Journal of Experimental Zoology 271.6 (1995): 441-451.
Niwa, Tohru, et al. "Isolation of a genetic marker linked to the Bh gene by genetically directed representational difference analysis of closed colony Japanese quails." Zoological science 18.1 (2001): 37-41.
Niwa, Tohru, et al. "Plumage pigmentation and expression of its regulatory genes during quail development–histochemical analysis using Bh (black at hatch) mutants." Mechanisms of Development 118.1-2 (2002): 139-146.
SHIOJIRI, N., NIWA, T., WAKAMATSU, K., ITO, S., & NAKAMURA, A. (1999). Chemical Analysis of Melanin Pigments in Feather Germs of Japanese Quail Bh (Black at Hatch) Mutants. Pigment Cell Research, 12(4), 259–265. doi:10.1111/j.1600-0749.1999.tb00759.x
MINEZAWA, M., & WAKASUGI, N. (1977). STUDIES ON A PLUMAGE MUTANT (BLACK AT HATCH) IN THE JAPANESE QUAIL. The Japanese Journal of Genetics, 52(3), 183–195. doi:10.1266/jjg.52.183
Niwa, Tohru, et al. "The Bh (black at hatch) gene that causes abnormal feather pigmentation maps to chromosome 1 of the Japanese quail." Pigment cell research 16.6 (2003): 656-661.
