RIKEN fly study: gut cell turnover tracks cytoplasmic fluidity, not single nutrients

Researchers led by Sa Kan Yoo at RIKEN's Center for Biosystems Dynamics Research report that gut cell turnover in fruit flies depends on how much food the animals get and on how fluid the insides of gut cells become, not on any single nutrient pathway, phys.org reported, citing PNAS. The team studies erebosis, a form of gut cell death tied to rapid lining replacement. Erebosis rose on low-yeast, high-sugar diets; cutting amino acid concentration by 90% triggered it, but blocking classic amino-acid signaling did not stop it, and individual amino acids at diet levels failed to suppress it. A non-metabolizable amino acid analog and other molecules that thicken cytoplasm without being metabolized suppressed erebosis, leading the authors to propose "viscosatiety," in which gut cells sense hunger or satiety via cytoplasmic viscosity. The paper is Nakamura et al., DOI: 10.1073/pnas.2602724123. The lab is checking whether erebosis occurs in mice and humans.