Inter-kingdom lipid transfer mediates D. melanogaster temperature-adaption
Authors: Claudia Espinoza; Itay Budin
Affiliation: University of California San Diego
Keywords: t. other (interspecies lipid transfer ); d. membrane dynamics
Animals must undergo physiological modifications to adapt to yearly climate fluctuations. At low temperatures, cell membranes undergo a phase transition from liquid to gel-like state, lowering membrane fluidity and disrupting the function of essential membrane-associated machinery. In organisms that overwinter, a class of lipids in their membranes, polyunsaturated fatty acids (PUFAs) with 2-6 double bonds, can act to maintain membrane fluidity and function at low temperatures. However, most animals, including Drosophila, lack the desaturase enzymes responsible for the synthesis of PUFAs, and must rely solely on dietary sources to obtain this lipid class. This lipid exchange underlying the interplay between foraging behavior, food composition and cell membrane organization, which is crucial for organisms’ seasonal adaptation, remains unexplored. Using Drosophila melanogaster and different yeast species as its dietary counterpart, we are investigating how PUFAs obtained through diet determine seasonal adaptation and what the mechanisms of PUFA detection and selection are. Analysis of D. melanogaster associated yeast collected at different times of the year allowed us to identify the increase in PUFA-producing species during the cold months. In the lab, we find that controlled dietary intake of yeast PUFAs dictates Drosophila activity at low temperatures. Lipidomics analysis shows how the presence of the key temperature-responsive PUFA linolenic acid is determined in specific lipid classes as a function of diet. We also find that temperature also determines both feeding and oviposition preferences, with flies favoring feeding from and laying eggs near PUFA-producing yeast at low temperatures. Using a combination of mass spectrometry, feeding assays, and yeast and Drosophila mutants, we are currently elucidating the yeast volatiles and Drosophila genetic pathways responsible for the detection and selection of dietary PUFAs at low temperature. This knowledge will help us understand the mechanisms by which lipid exchange influences seasonal adaptation in symbiotic organisms like yeast and Drosophila.