Geneticists love fruit flies because they share around 60% of our genes and have lessons to share about how life works. Like humans, male and female fruit flies grow at different rates. But while sex-specific genes control growth-boosting hormones in our bodies, flies didn’t seem all that similar – until now. Flies have a gene called sex-lethal (Sxl) that switches on differently in males or females. In developing fly brains, like this one (with all cells stained blue) scientists found that Sxl works in two different types of neurons – making them more active in males or females – to control the male/female size gap. While one type is involved in sending signals within the brain (such as the type coloured here) another produces the hormone insulin. This link between sex-specific genes and hormone control during development brings humans and flies even closer – useful when trying to understand how the different sexes develop.
Written by John Ankers
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