Sex in birds is chromosomally based, as in mammals, but the sex chromosomes are different and the mechanism of avian sex determination is a long-standing mystery. In the chicken and other birds, the homogametic sex is male (ZZ) and the heterogametic sex is female (ZW). Two hypotheses have been proposed for the mechanism of avian sex determination. The W (female) chromosome may carry a dominant-...

Sex in birds is chromosomally based, as in mammals, but the sex chromosomes are different and the mechanism of avian sex determination is a long-standing mystery. In the chicken and other birds, the homogametic sex is male (ZZ) and the heterogametic sex is female (ZW). Two hypotheses have been proposed for the mechanism of avian sex determination. The W (female) chromosome may carry a dominant-...

Sex in birds is chromosomally based, as in mammals, but the sex chromosomes are different and the mechanism of avian sex determination is a long-standing mystery. In the chicken and other birds, the homogametic sex is male (ZZ) and the heterogametic sex is female (ZW). Two hypotheses have been proposed for the mechanism of avian sex determination. The W (female) chromosome may carry a dominant-...

A century ago, Bridges proposed that male genes on the autosomes and female genes on the X chromosome compete to determine sexual identity. New genetic and molecular studies establish Caenorhabditis elegans as the first animal known to use this mechanism.

Polygenic sex determination, although suspected in several species, is thought to be evolutionarily unstable and has been proven in very few cases. In the European sea bass, temperature is known to influence the sex ratio. We set up a factorial mating, producing 5.893 individuals from 253 full-sib families, all reared in a single batch to avoid any between-families environmental effects. The pr...

A fingerprint found at the crime scene is one of the most crucial fragments of personal identification that a person might leave behind. Apart from being every person’s unique identification mark that are ubiquitous to all, to start with, they often reveal on further examination, certain characteristics about the person that might narrow down the suspects’ pool. To identify criterions that can ...

BACKGROUND All honey bee species (Apis spp) share the same sex determination mechanism using the complementary sex determination (csd) gene. Only individuals heterogeneous at the csd allele develop into females, and the homozygous develop into diploid males, which do not survive. The honeybees are therefore under selection pressure to generate new csd alleles. Previous studies have shown that t...

Sexual dimorphism in humans has been the subject of wonder for centuries. In 355 BC, Aristotle postulated that sexual dimorphism arose from differences in the heat of semen at the time of copulation. In his scheme, hot semen generated males, whereas cold semen made females (Jacquart, D., and C. Thomasset. Sexuality and Medicine in the Middle Ages, 1988). In medieval times, there was great contr...

The genetic cascades regulating sex determination of the housefly, Musca domestica, and the fruitfly, Drosophila melanogaster, appear strikingly different. The bifunctional switch gene doublesex, however, is present at the bottom of the regulatory cascades of both species, and so is transformer-2, one of the genetic elements required for the sex-specific regulation of doublesex. The upstream re...