Working group session:
Functional Genomics
Presentation type:
oral
Authors:
Liu, Gao-Jun; Qin, Yong-Mei
Presenter:
Qin, Yong-Mei
Correspondent:
Qin, Yong-Mei
Abstract:
Very long-chain fatty acids (VLCFAs) are predominantly present in the form of sphingolipids, which are essential components of plasma membrane microdomains (lipid rafts) that mediate signal transduction pathways in a wide range of eukaryotic organisms, we speculate that sphingolipid may exert an important function during G. hirsutum fiber development. Five groups of cotton sphingolipids including ceramides, hydroxyceramides, inositolphosphoceramides, glucosylceramides, and glycosylinositolphosphoceramides were quantified by using 5500 QTRAP mass spectrometer. Ceramides and inositolphosphoceramides containing VLCFAs accumulated in fast elongating fibers. Ceramides are bioactive lipids and precursors to sphingolipids and have been shown to take part in a wide variety of different physiological processes in eukaryotic organisms and are thought to be toxic at high concentrations. Ceramides are synthesized by condensation of the sphingoid base sphinganine and a fatty acyl CoA by ceramide synthases, a family of enzymes that differ in their specificity for the length of the acyl CoA substrate. A yeast strain in which the endogenous ceramide synthase was replaced by a cotton gene GhLag1, resulting in yeast cells producing C18 rather than C26 dihydroceramides indicating that GhLag1 is a bona fide ceramide synthase with specificity towards C18 acyl CoA. Further, the yeast cells expressing GhLag1 after deletion of the normally essential AUR1 encoding inositol phosphorylceramide synthase is viable, and are delayed in cytokinesis. The data suggest the essential roles of complex sphingolipids in controlling cytokninesis in eukaryotic cells.