Intersex people are not biologically male or female but can have characteristics of both.
For a new study with mice, researchers observed that, despite having a Y chromosome, rodents lacking the “Jmjd1a” enzyme developed as females. The findings are detailed in a study published in the journal Science.
The discovery provides new information on the earliest steps the body takes in becoming male or female, says Peter Koopman, a professor from the University of Queensland’s Institute for Molecular Bioscience.
“Most mammals, including humans and mice, are programmed to develop as females unless a specific Y-chromosome gene called Sry is present to trigger male development during embryonic life.
“We knew that Sry is responsible for switching on maleness genes, but what we didn’t know is that the DNA containing Sry needs be unwound before the gene can become active. It’s as if the DNA is a ball of string that needs to be unraveled by Jmjd1a to expose the Sry gene before it can be used.
“This latest discovery has put the spotlight on DNA packaging as a major determinant of the sex of the embryo. In broader terms it continues to open our eyes to the enormous amount of activity occurring in every cell to coordinate when and where each of our 30,000 genes is active—it’s a huge logistical task.
“Fundamental discoveries like this bring us a step closer to controlling stem cell behavior by activating or repressing certain genes.”