Meeting Abstract

P2.33  Monday, Jan. 5  Sex-biased gene expression in the intertidal copepod Tigriopus californicus HARRISON, J.S.*; BURTON, R.S.; Georgia Southern University, Statesboro; Scripps Institution of Oceanography, La Jolla, California sharrison@georgiasouthern.edu

The intertidal copepod Tigriopus californicus has become an exciting system to investigate the genetics of population structure and outbreeding depression. Recent studies in this species suggest that the detrimental effects of hybridization between genetically differentiated populations are not always expressed equally in both sexes. In fact, little is known about the genetic, and/or physiological differences between sexes of this copepod species; the mechanism underlying sex determination itself remains undetermined. Here we use a custom 2000 feature cDNA microarray to investigate patterns of gene expression in males and females of T. californicus. The main objective of this study is to characterize differences in the transcriptome between sexes. Using conservative criteria in our analysis, 17.2% of the ESTs exhibited sex-biased expression levels (a minimum estimate). Of the ESTs showing sex-biased expression, 58.6% were expressed at a higher level in females and 41.4% were expressed at a higher level in males. The ESTs showing the highest levels of differential expression were strongly biased in the female direction, while those showing lower levels if differential expression were partitioned equally between the sexes. Similar to studies in other arthropods, a high proportion of female biased genes fell into two general functional groups; 1) protein processing, and 2) RNA/DNA processing. However, genes functioning in innate immunity such as those involved in antimicrobial response also showed strong female biased expression. The suite of ESTs showing male biased expression was largely dominated by genes involved in muscle function and development.