Snake W Sex Chromosome: The Shadow of Ancestral Amniote Super-Sex Chromosome

Sex determination in birds: HINTs from the W sex chromosome?

Sex in birds is controlled genetically (ZZ male: ZW female), but the genetic mechanism remains unclear. While some evidence points to the involvement of Z sex chromosome dosage, other data favour a dominant female-determining gene carried on the W sex chromosome. An intriguing candidate gene located on the chicken W chromosome is HINTW, which encodes an aberrant form of a hydrolase enzyme. In c...

Karyotype and Sex-Chromosome Polymorphism in Nesokia indica, from Iran

Parallel divergence and degradation of the avian W sex chromosome.

Sex chromosomes are ubiquitous in birds but our understanding of how they originated and evolved has remained incomplete. Recent work by Tsuda et al. on tinamou and ratite birds suggests that, although all bird sex chromosomes evolved from the same pair of autosomes, the Z and W sex chromosomes have diverged from one another several times independently. This parallel evolution of the avian W pr...

Sex Chromosome Meiotic Drive

Meiotic sex chromosome inactivation

X chromosome inactivation is most commonly studied in the context of female mammalian development, where it performs an essential role in dosage compensation. However, another form of X-inactivation takes place in the male, during spermatogenesis, as germ cells enter meiosis. This second form of X-inactivation, called meiotic sex chromosome inactivation (MSCI) has emerged as a novel paradigm fo...