The identification of genes from the oyster Crassostrea gigas that are differentially expressed in progeny exhibiting opposed susceptibility to summer mortality

Abstract

Summer mortality associated with juveniles of the oyster Crassostrea gigas is probably the result of a complex interaction between the host, pathogens and environmental factors. Genetic variability in the host appears to be a major determinant in its sensitivity to summer mortality. Previously, divergent selection criteria based on summer survival have been applied to produce oyster families with resistant and susceptible progeny. In this paper, we describe the use of suppression subtractive hybridization to generate 150 C. gigas clones that were differentially regulated between resistant and susceptible F2 progeny. The nucleotide sequence of these clones was determined. In 28%, the inferred amino sequence was found to match the products of known genes, 14% matched hypothetical proteins and a further 14% appeared to contain open reading frames (ORFs) whose product had no obvious homologue in the nucleotide databases. It has been hypothesized that differences exist in the level of energy generation and immune function between resistant and susceptible progeny. In light of this, clones encoding homologues of cavortin, cyclophilin, isocitrate dehydrogenase, sodium glucose cotransporter, fatty acid binding protein, ATPase H+ transporting lysosomal protein, precerebellin, and scavenger receptor were analyzed by real-time PCR. These transcripts were induced in resistant progeny when compared to their susceptible counterparts. A bacterial challenge of oysters resulted in the suppression of six of these transcripts in only those that were resistant to summer mortality. This study has identified potential candidates for further investigation into the functional basis of resistance and susceptibility to summer mortality.

Summer mortality of hatchery-produced Pacific oyster spat (Crassostrea gigas). I. Estimation of genetic parameters for survival and growth

“…Only a few studies provide estimates of heritability for survival in marine mollusks to compare with our present results. Low estimated heritabilities for survival were found in Mytilus edulis (0-0.15) (Mallet et al,, 1986) The high heritability estimate obtained in our study also suggests that resistance to summer mortality might be controlled by a limited number of genes (Huvet et al, 2004).…”

Transcriptional expression levels of cell stress marker genes in the Pacific oyster Crassostrea gigas exposed to acute thermal stress

“…Moreover, it should be kept in mind that temperature is not the only parameter changing with the seasons and suspected to be responsible for stress in oysters. Other parameters include environmental factors such as trophic conditions, oxygen and nature of sediment (Delaporte et al 2003;Soletchnik et al 2005) as well as physiological and genetic factors such as reproduction, oxidative stress and parasitism (Le Roux et al 2002;Huvet et al 2004;Costil et al 2005). …”

Identification of a novel sodium-dependent fructose transport activity in the hepatopancreas of the Atlantic lobsterHomarus americanus

“…EX471402) was submitted to BLAST (Altschul et al, 1997) analysis using human SGLT4 (Tazawa et al, 2005), rabbit SGLT1 (Hediger et al, 1987), mouse (Accession no. AAF17249) SGLT1, Pacific oyster SGLT (Huvet et al, 2004), rat GLUT2 (Fisher et al, 2008) and rat GLUT5 (Rand et al, 1993) protein sequences for identification of expressed lobster sugar transport orthologues. Lobster EST clones with significant identity to mammalian and other sugar transport proteins were aligned with mammalian SGLTs and GLUTs to indicate the degree of identity between the lobster and mammalian proteins (Tatusova and Madden, 1999;Larkin et al, 2007).…”