Meeting Abstract

13.2  Friday, Jan. 4  Amino acid transport as an index of growth potential in larvae of the Pacific oyster, Crassostrea gigas PAN, F.*; APPLEBAUM, S.L.; MANAHAN, D.T.; Univ. Southern California, Los Angeles

All soft-bodied marine invertebrates are capable of transporting dissolved free amino acids from low concentrations found in natural seawater. While the physiology of this process has been well characterized over the past 50 years, little is known about the genetic and molecular biological bases of transport capacity. In this study, bivalve larvae with contrasting growth phenotypes were produced by experimentally crossing purebred adults from pedigreed families. Eight larval families reared under similar environmental conditions showed contrasting growth rates, ranging from 5.4 ± 0.6 (SEM) to 14.8 ± 0.4 micrometers per day. Amino acid (glycine) transport rates were measured during growth of these larval families at substrate concentrations near Kt (concentration of substrate resulting in half-maximum transport rate) and Jmax (maximum transport rate). Transport rates at both substrate concentrations increased with larval size. Rates measured at Kt remained the same between phenotypes; however, size-specific Jmax was higher in larvae with fast-growing phenotypes. These findings suggest that there is a genetic basis for physiological variation in transport rate. Current research is focused on the quantification of the genes encoding amino acid transporters. The positive correlation of growth phenotype with transport capacity indicates that expression of transporter genes could provide a physiological index of growth potential early in development.