Meeting Abstract

72.4  Monday, Jan. 6 08:45  Genes, genomes and proteins – the challenge of making physiological predictions MANAHAN, D.T.*; APPLEBAUM, S.L.; PAN, F.; Univ. Southern California manahan@usc.edu

Dramatic advances in nucleic acid sequencing technology are providing unprecedented abilities to quantify gene expression and abundances of mRNA in organisms. Beyond the study of single genes, genome science is opening up new understandings of “non-model” organisms that are of great interest to comparative biologists. A common assumption in many of these studies is that changes in mRNA abundance are an indicator of physiological activity. Recent tests of this assumption, however, show that steady-state transcript levels are often poor predictors of protein abundances and physiological rates. Our studies of epithelial transport processes in developing sea urchins have shown that (1) gene expression of ion transporters did correspond to the amount of protein (Na⁺, K⁺-ATPase) in some stages, but not all, and (2) the amount of total protein never corresponded to the measured physiological rate of ion transport. Genome analysis reveals that many more genes than those commonly identified are involved in single transport processes. In the bivalve Crassostrea gigas there are several gene families, one of which (Solute Carrier Family 6) contains ~30 gene predictions for amino acid transporters, each expressed in larvae. This situation is similar to the genetic complexity regulating other physiological responses: e.g., the C. gigas genome contains 88 heat shock protein 70 genes. Genome science is providing important insights into the biological complexity underlying physiological processes. It seems unlikely, however, that gene or protein expression assays alone will provide useful predictions of many physiological rate processes. Rather, elucidation of the physiological function of individual genes and defining the relative contribution of multiple genes to single physiological processes, is required.