Master gene regulates physical differences between the sexes

Have you ever wondered how males and females can belong to the same species but exhibit such different physical traits? It turns out that these differences are controlled by a master gene, called “doublesex” or dsx, that matches each trait to each sex. Now, a new study from researchers at Indiana University has shed new light on the complex ways in which dsx regulates physical differences between the two sexes.

The study, published in Nature Communications, is the first to observe dsx across the entire genome. The researchers found that the master gene does not behave simply as a “switch” that turns off male features in females and female features in males. Instead, dsx plays a complex role in regulating how the physical differences are expressed at different points in the genome.

“We want to know more about this gene because it helps us answer a major question about development and evolution: How do animals with similar genomes — such as males and females of the same species — produce different versions of the same trait? And why do some traits, like ornamental features that attract mates, vary so widely, while others, like legs, don’t?” said Cris Ledón-Rettig, who led the study.

According to Ledón-Rettig, dsx can activate different genes in males and females that promote different versions of the same trait. It can also activate genes in males and inhibit those genes in females, thus creating opposing traits.

“The power to prevent the expression of male traits in females, and vice versa, is a critical feature,” said Armin Moczek, senior author of the study. “It buffers traits that benefit only members of one sex from causing harm in members of the other.”

The team studied Onthophagus taurus, a species of beetle in which males have horns to battle rivals over females. However, the horns don’t appear on the females because they would get in the way of their ability to dig tunnels to build nests. Similarly, in many bird species, males have high testosterone because the aggression attracts more mates. But high testosterone does not appear in females as it would decrease maternal instinct.

“Essentially, dsx instructs the development of male and female versions of the same trait by influencing different genes in each sex,” said Ledón-Rettig.

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By Rory Arnold, Earth.com Staff Writer

Source: Indiana University