An Examination of Heterosis in Crosses of Certain Inbred Strains of Mice

Author Institution: Department of Dairy Science, The Ohio State University, and Battelle Memorial Institute, Columbus, Ohi

Inheritance of Black Hair Patterns in Cattle Lacking the Extension Factor for Black (E.). IV, Partitioning Phenotypes by Castration

Author Institution: Department of Dairy Science, Ohio Agricultural Experiment Station, Wooste

Inheritance of Black Hair Patterns in Cattle Lacking the Extension Factor for Black (E.). III, A Multiple Allelic Hypothesis to Explain the Inheritance of Blackish and Blackish Pattern

Author Institution: Department of Dairy Science and the Institute of Genetics, The Ohio State University, Columbus and Department of Dairy Science, The Ohio Agricultural Experiment Station, Wooste

The Chemical Composition of Cattle Hair. I, The Fat, Ash and Nitrogen Content

Author Institution: Ohio Agricultural Experiment Station, Wooste

Avian W and mammalian Y chromosomes convergently retained dosage-sensitive regulators

After birds diverged from mammals, different ancestral autosomes evolved into sex chromosomes in each lineage. In birds, females are ZW and males are ZZ, but in mammals females are XX and males are XY. We sequenced the chicken W chromosome, compared its gene content with our reconstruction of the ancestral autosomes, and followed the evolutionary trajectory of ancestral W-linked genes across birds. Avian W chromosomes evolved in parallel with mammalian Y chromosomes, preserving ancestral genes through selection to maintain the dosage of broadly expressed regulators of key cellular processes. We propose that, like the human Y chromosome, the chicken W chromosome is essential for embryonic viability of the heterogametic sex. Unlike other sequenced sex chromosomes, the chicken W chromosome did not acquire and amplify genes specifically expressed in reproductive tissues. We speculate that the pressures that drive the acquisition of reproduction-related genes on sex chromosomes may be specific to the male germ line