Comparative biochemistry of lipid and protein metabolism in marine invertebrate larvae from warm and cold environments

From the simplest single celled organisms to complex multicellular animals, metabolic regulation of changes in quantity and quality of proteins and lipids are essential to life. In this dissertation, the metabolism of protein and lipid synthesis and utilization was examined in developing embryos and larvae of species of marine invertebrates. Differential protein expression and lipid metabolism was studied during the early larval development of slow- and fast-growing larval families the Pacific oyster (Crassostrea gigas). Early larval stages possessed more protein than lipid reserves, however triacylglycerols were used to fuel early development to the feeding larval stage. Differential protein expression was measured by two-dimensional gel electrophoresis and a complex pattern of differential protein expression was observed for some of the acidic proteins, suggesting possible markers for "egg quality" in setting quantitative traits in larvae.; The cost of protein synthesis was measured in the homogenates made from embryos of several species of temperate and Antarctic echinoderm using cell-free protein translation assays. The costs of protein synthesis in the three temperate echinoderm species studied ranged from 3.66 +/- 0.79 to 8.33 +/- 3.13 J (mg protein synthesized)-1, which is consistent with values that have been reported in the literature for other temperate species of animals. In contrast, however, significantly lower costs of protein synthesis were measured in Antarctic echinoderm species of 0.41 +/- 0.15 to 1.79 +/- 0.55 J (mg protein synthesized)-1. This low cost of protein synthesis observed in the Antarctic species suggests a potential adaptation to life in cold and nutrient-poor environments by having a low "cost of living."; The egg lipid content was studied in several species of Antarctic echinoderm. Normal development was negatively impacted by low amounts of initial triacylglycerol content in the herbivorous Antarctic sea urchin S. neumayeri. In two congener species of predatory Antarctic sea star O. validus and O. meridionalis, variability in the egg lipid content of females was observed, but lipid reserves were sufficient in these species for normal development to proceed. The data presented here on maternal investment in eggs suggests the occurrence of nutritional stress in adult females of S. neumayeri.