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R G Somes

Publications and source records attributed to R G Somes.

43 records · Page 3Linked to original sources
PubMedDate not supplied

Inheritance of the henny feathering trait in the golden Campine chicken: evidence for allelism with the gene that causes henny feathering in the Sebright bantam.

The henny feathering mutation causes roosters to develop female feathering morphology as a result of increased conversion of androgen to estrogen (aromatase activity) in extraglandular tissues, including skin. This trait is maintained in two breeds of chickens: the Sebright Bantam and the Golden Campine. To characterize the inheritance of this trait further, we did breeding studies of the Golden Campine and identified the trait by measuring aromatase activity in biopsied skin. As previously established for the Sebright Bantam, the trait is transmitted in the Campine by an autosomal, incomplete dominant mechanism; heterozygous offspring express half the levels of extraglandular aromatase as do homozygous Campines on average. No reversions to wild-type levels were observed in 555 heterozygous offspring of crosses between homozygous Campines and normals. Compound heterozygotes for the trait were obtained by mating homozygous Sebrights and homozygous Campines. When these compound heterozygote birds were crossed to control birds, all 98 offspring had elevated aromatase activity in skin, suggesting that the traits in Sebright and Campine birds are allelic. Furthermore, the restriction fragment length polymorphism pattern performed on genomic DNA was the same in the Sebright and Campine birds. Thus, the phenotypic, endocrine, and genetic features suggest that the traits in Sebright and Campine birds are the same. The trait in the Campine probably was derived from the Sebright.

Alleles↗
PubMedDate not supplied

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. When the duplex comb types were crossed to each other, the V-shaped comb showed complete dominance over the buttercup comb. It is proposed that there are at least three alleles at the duplex locus: D (v-type) greater than Dc (buttercup type) greater than d+ (non-duplex type). The most dominant allele (Dv) causes both doubling of the comb and suppression of its tissue mass, while the less dominant allele (Dc) only causes doubling of the comb.

Alleles↗
PubMedDate not supplied

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. In this case the inheritance appears dominant. It is proposed that cavernous nostrils are a pleiotropic effect of the comb-size-reducing ability of the Dv allele rather than its duplexing ability.

Alleles↗
PubMedDate not supplied

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. The trait appears to affect liveability beyond that which might be expected of blind individuals. Embryonic mortality was increased five-fold among microphthalmic individuals, and all but two of the 35 microphthalmic chicks that hatched died within a week. Data from various crosses indicate that this condition is inherited as an autosomal recessive with expression being limited primarily to females. The name microphthalmia-4 and the gene symbol mi-4 are proposed for this trait.

Animals↗
PubMedDate not supplied

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. The Brahma allele was shown to be dominant over the Langshan allele. Both the Sultan and Cochin breeds were shown to possess two shank-feathering loci, and the data suggested that one of the loci in the Sultan contained the Pti-1L allele. It is hypothesized that the comparable allele in the Cochin breed was Pti-1B. It is proposed that the second locus in both of these breeds is similar, and the symbol Pti-2 is suggested.

Alleles↗