Identifying the ptilopody (feathered shank) loci of the chicken.

A series of crosses was made involving lightly-, and heavily-, and non-feather-shanked chickens in an attempt to clear up the confusion in the literature concerning the inheritance of feathered shanks in chickens. The Langshan and Brahma breeds were both shown to possess the same single shank-feathering locus, but because of their differences in phenotype and penetrance in the genetic crosses it was suggested that they possessed different alleles at this locus. This locus was designated as Pti-1, with Pti-1L being the Langshan allele and Pti-1B the Brahma allele.

Microphthalmia-4: a sex-influenced inherited eye condition of the chicken.

A new mutation of the chicken that causes a reduction in eyeball size is described. Eyeball size reduction is extreme in over 80% of affected individuals. Two-thirds of affected chickens have bilateral expression, while the rest are unilaterally affected.

Some observations on high cavernous nostrils in the chicken.

Wide high cavernous nostrils are characteristic of all chicken breeds of the V-shaped duplex comb type, whereas all other breeds have slit-type nostrils, including the Sicilian Buttercup breed that has the buttercup-type duplex comb. Crosses between the Sicilian Buttercup and La Flèche breeds and single comb breeds suggest that this trait is a pleiotropic effect of the Dv allele at the duplex locus and is inherited as a recessive when crosses are made to the wild type (d+). The buttercup allele (Dc) at this same locus does not influence nostril morphology by itself, but, when combined with the V-shape comb allele (Dv/Dc), it does allow a single Dv allele to produce mutant nostrils.

Duplex comb in the chicken: a multi-allelic trait.

Allelism at the duplex comb locus was studied by means of crosses between the Sicilian Buttercup and La Flèche breeds of chickens and two single combed breeds. The horn V-shaped duplex comb of the La Flèche was shown to be inherited as an incomplete dominant when crossed with single comb birds, and it exhibited complete penetrance and a strong expression of duplex. The buttercup duplex comb of the Sicilian Buttercup in similar crosses was also shown to be inherited as an incompletely dominant trait, but with this type comb penetrance was reduced by 32% in females and its expression of duplex was greatly reduced when compared with the La Flèche.

Recessive inherited doubling of the chicken's uropygial gland papilla.

A new mutation that causes doubling of the uropygial gland (oil gland) papilla is described, and data that demonstrate its inherited basis are presented. This condition, which has been given the name "double oil gland papilla," varies in its expression: some individuals show only an indention of the papilla tip, while others exhibit a complete cleavage of the papilla such that two completely separate papillae project from a single oil gland. The data presented show that a single autosomal recessive gene, dgp, is the main determinant of this trait, but that its expression may also be influenced by background genetic factors as well as sex.