A new study led by Alisson Gontijo, Principal Investigator of the Integrative Biomedicine Laboratory at NOVA Medical School, published in the prestigious journal Proceedings of the National Academy of Sciences (PNAS) has uncovered the neural mechanisms underlying a complex innate behavior in fruit flies (Drosophila melanogaster) - a discovery that could offer broader insights into how the brain orchestrates hardwired behaviors across species.
The research focuses on pupariation, a critical developmental transition during which fruit fly larvae transform their soft, elongated bodies into hardened capsules called puparia, marking the beginning of metamorphosis. This transformation, which includes body remodeling, the secretion of a glue-like substance to stick to a surface, and the hardening of its skin to a protective shell, is executed through a multi-stage motor sequence that does not require prior experience or learning.
Gontijo’s team previously identified a hormonal signal required to initiate this sequence, but the new study goes further by mapping specific neurons and signaling molecules that fine-tune and activate one specific step of the sequence - the glue expulsion and spreading behavior (GSB) that helps larvae stick to their surroundings.
The researchers identified a pair of descending neurons that connect the brain to the motor control system, acting as both command and neuromodulatory neurons. They work like “switches”: turning on the glue expulsion and spreading behavior at the right moment. At the same time, they fine-tune when and how this behavior happens using a signaling molecule called Mip, which acts on a receptor known as SPR - a protein related to some human receptors whose roles are still not well understood.
This finding is particularly significant because it shows how the brain links internal signals to specific motor outputs - especially for instinctive actions that don’t require learning. Although fruit flies have over 1,000 descending neurons, only a small fraction have been studied in detail, making this work a valuable step toward decoding the neural control of innate behaviors.
Moreover, the use of Drosophila as a model highlights the power of simple organisms in unraveling the biology behind behavioral control - insights that may one day inform our understanding of human neurology and disorders involving motor function or neuromodulation.
Other contributing authors of the published paper include members of the Integrative Biomedicine Laboratory at NOVA Medical School - co-first authors Magdalena Fernandez-Acosta and Rebeca Zanini; researchers Fabiana Heredia, Juliane Menezes, and Katja Prüger; and co-corresponding author Andres Garelli - as well as collaborators from France, Germany, and Argentina.
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