Secrets Of Metamorphosis: New Study Reveals Gene Expression Model During Fly Development

Moscow, June 25, 2025

Researchers from Skoltech, Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, and Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences have studied gene expression dynamics during metamorphosis in two species of flies. The study aims to identify patterns of changes in gene activity during insect development that undergo complete metamorphosis — from egg to larva, pupa, and adult. The results were published in the Genome Biology and Evolution journal.

Every day we are surrounded by thousands of flies, mosquitoes, beetles, butterflies, and many other insects that go through several stages of development — for example, a caterpillar transforming into a beautiful butterfly. Each stage activates different sets of genes, allowing these insects to adapt to various environments. In their new study, scientists investigated how gene activity levels change at different developmental stages of two fly species — Drosophila melanogaster and Drosophila virilis.

“In our previous work, we showed that metamorphosis is similar to embryogenesis—that is, organism development from fertilised egg cell to fully formed embryo. Both processes involve organ and tissue formation since there is significant restructuring from larvae to adults during metamorphosis. During embryogenesis, the hourglass hypothesis suggests that different species exhibit striking similarities at a mid-developmental stage, forming a ‘narrow neck’ where gene activation patterns converge. We tested whether this hypothesis applies to metamorphosis,” commented Alexandra Ozerova, the lead author of the paper and PhD student at Skoltech’s Life Sciences program.

Results of the new study revealed a completely different scenario — the dynamic of gene activity resembles a spindle rather than an hourglass. Instead of a narrow point with similarities between species, diversity increases over time.

“We conducted RNA sequencing experiments for both drosophila species, collecting samples at different life cycle stages: embryos, larvae, various pupal stages, and adults. For analysis, we used bioinformatics methods. We found that genes which emerged relatively recently in insect evolution begin actively expressing themselves during the mid-pupal period, their expression level sharply rises. It can be assumed that they help the organism carry out necessary physiological transformations leading to adulthood,” added a study co-author, Professor Mikhail Gelfand, the vice president for biomedical research at Skoltech.

Insects undergoing full transformation cycles are more evolutionarily successful — they include the most numerous groups by number of species (e.g. beetles, mosquitoes, flies, bees, ants, butterflies). Many of them turn out to be pests. A better understanding of biological processes at different stages of development opens up new prospects for developing effective control measures against them. Knowing specifics about gene expression could lead to designing drugs targeting vulnerable stages of insect development.

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Skoltech is a private international university in Russia, cultivating a new generation of leaders in technology, science, and business. As a factory of technologies, it conducts research in breakthrough fields and promotes technological innovation to solve critical problems that face Russia and the world. Skoltech focuses on six priority areas: life sciences, health, and agro; telecommunications, photonics, and quantum technologies; artificial intelligence; advanced materials and engineering; energy efficiency and the energy transition; and advanced studies. Established in 2011 in collaboration with the Massachusetts Institute of Technology (MIT), Skoltech was listed among the world’s top 100 young universities by the Nature Index in its both editions (2019, 2021). On Research.com, the Institute ranks as Russian university No. 2 overall and No. 1 for genetics and materials science. In the recent SCImago Institutions Rankings, Skoltech placed first nationwide for computer science.

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