Regulation of oosporogenesis by Lagenidium giganteum; promotion of sexual reproduction by unsaturated fatty acids and sterol availability

Abstract

Induction and maturation of the sexual oospores of the facultative mosquito parasite Lagenidium giganteum (Oomycetes: Lagenidiales) are influenced by exogenous lipid media supplements. Sterols structurally related to cholesterol are necessary for induction of sexual reproduction and possibly have at least a structural role in oospore maturation following spore wall formation. Sterols also enhance uptake of certain exogenous fatty acids from growth media. Palmitoleic, oleic, and linoleic acids, especially when added to media as triacylglycerols, enhance oospore induction and maturation. It is hypothesized that enrichment of the fatty acyl compounds of the fungus with unsaturated moieties affects cyclic nucleotide metabolism and promotes cellular and vesicular fusion events associated with oosporogenesis by regulating (increasing) membrane fluidity. Results are discussed in relation to mediation of fusion events in a number of diverse model membrane and biological systems by fatty acids and sterols.