Plant, Animal & Microbe Genomes X Conference

January 12-16, 2002
Town & Country Convention Center
San Diego, CA

Workshop: Aquaculture
            

ANALYSIS OF GENE EXPRESSION IN HYBRID PACIFIC OYSTERS BY MASSIVELY PARALLEL SIGNATURE SEQUENCING

¹ University of California, Davis, Bodega Marine Laboratory, 2099 Westside Rd., Bodega Bay, CA 94923-0247 USA

² Lynx Therapeutics, Inc., 25861 Industrial Blvd. Hayward, CA 94545, USA

³ Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0371, USA

We cloned on plastic beads (Brenner et al. 2000 PNAS 97:1665) and sequenced, by massively parallel signature sequencing technology (MPSSŪ; Brenner et al. 2000 Nature Biotechnology 18:630), 3.1 million cDNAs from inbred and hybrid larvae produced by reciprocal crosses of inbred lines 35 and 51 of the Pacific oyster. Both reciprocal hybrids showed heterosis in shell size at day 5 and growth rate from day 2 to day 5. The clone count for the majority of cDNAs either did not vary significantly between inbreds and hybrids or behaved additively, because there was no significant deviation in the hybrids from the expected mid-parent level. A small proportion of cDNAs (<5%), however, exhibited a pattern of expression that was significantly non-additive in each hybrid (p<0.001). Amongst the non-additively expressed cDNAs, expression in the hybrid was either different from both inbred parents or like one inbred parent but not the other. Significantly, the largest class of non-additively expressed cDNAs (>500 in each hybrid; p<0.001) was over-expressed relative to both inbred parents. About 150 cDNAs that are likely to be associated with growth heterosis, because they exhibit the same pattern of non-additive expression in both reciprocal hybrids, have been selected for further study. Confirmation of expression levels by RT-PCR and sequencing of full-length cDNAs are in progress. This study illustrates how the genetic basis of a complex biological trait like heterosis can be addressed by technology for comprehensive gene-expression profiling like MPSSŪ, even when the genome of the organism is poorly characterized.