GELIFES Seminars - Ryusuke Niwa

Ryusuke Niwa (University of Tsukuba, Japan)

From homeostasis to hijacking

Molecular mechanisms of physiological and developmental regulation in Drosophila and parasitoid wasps

A central challenge in biology is to understand how physiological and developmental systems are maintained, and how they can be manipulated by parasites/symbionts. Using the fruit fly Drosophila melanogaster and its associated parasitoid wasps as experimental models, our laboratory investigates the molecular basis of both endogenous homeostasis and its disruption by external biological agents.

In the first part of this talk, I will present our recent work on calcium ion (Ca²⁺) homeostasis in Drosophila. Despite lacking both bones and vertebrate-like parathyroid hormone, insects must tightly regulate extracellular Ca²⁺ levels. We discovered that a neuropeptide called Capa acts as a key endocrine regulator of systemic Ca²⁺ homeostasis, revealing an unexpected mechanism for mineral balance in insects [Okamoto et al. Nature 2026, doi:10.1038/s41586-025-09670-z].

In the second part, I will discuss how parasitoid wasps manipulate host physiology and development through venom. Using the Drosophila parasitoid Asobara japonica, we identified novel venom factors that trigger selective degradation of host imaginal discs, thereby suppressing host development and promoting parasitism [Kamiyama et al. Science Advances 2025, doi:10.1126/sciadv.adq8771]. Ongoing comparative studies further explore how diverse parasitoid species evolutionarily optimize host manipulation strategies.

Biosketch:
Professor Ryusuke Niwa is a developmental biologist and physiological geneticist at University of Tsukuba in Japan, where he leads research at the Life Science Center for Survival Dynamics. His work focuses on the molecular, cellular, and neuroendocrine mechanisms that regulate development, reproduction, metabolism, and interorgan communication in insects, primarily using Drosophila melanogaster as a model system. Ryusuke has made major contributions to the understanding of insect steroid hormone biosynthesis, developmental timing, reproductive physiology, and host–parasite interactions. His interdisciplinary research also includes chemical biology approaches aimed at developing environmentally friendly insect control strategies. In addition to his research activities, he serves on the editorial boards of several international journals and plays active roles in the Japanese and international developmental biology communities.