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ARS Home » Research » Publications at this Location » Publication #41837
Title: OBSERVATIONS OF THE SEX-LINKED LATE-FEATHERING LOCUS IN CHICKENS

Author
item IRAQI FUAD - 3635-20-00
item Smith, Eugene

Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: A significant percentage of commercial egg-layer and broiler type chickens with the sex-linked, late-feathering mutation are marketed worldwide because early retardation of growth of wing feathers allows determination of the gender of chicks at hatch. On this basis, breeders of egg-layer type hens can cull unwanted males shortly after hatch. This mutation is also closely associated with inheritance of a retrovirus that impairs the normal immune response to infection by cancer-inducing strains of avian leukosis viruses. This report describes the molecular organization of a complex region surrounding the inherited virus. Results suggest that the virus gene and the gene that confers late-feathering are so closely linked that the task of selecting late-feathering chickens that lack the inherited virus would be formidable.

Technical Abstract: The sex-linked late-feathering (LF) haplotype of chickens comprises three components: the LF locus, K, the endogenous virus (ev) gene, ev21; and either one of two homologous ev21-unoccupied repeats URa or URb which are distinguished by restriction fragment length polymorphisms. Nucleotide sequence analysis of a cloned polymerase chain reaction product using primers that flank ev21, indicated that the Z chromosome of LF White Leghorns has two URa elements one of which harbors ev21. Pulsed-field gel electrophoresis of NotI, NaeI, KspI and BamHI digested DNA from early-feathering (EF) and LF White Leghorns hybridized with a 1.6 kb probe that flanks the ev21 integration site indicated a 180 kb duplication of URa sequences in LF genotype. It is proposed that during evolution, either duplication of URa or retroviral insertion led to the LF phenotype. Based on a survey of DNA from Asian breeds, LF may have originated in an Asian breed of chickens other than the red jungle fowl.