title: Differential effects of metal contamination on the transcript expression of immune- and stress-response genes in the Sydney Rock oyster, Saccostrea glomerata.
abstract: Environmental contamination by metals is a serious threat to the biological sustainability of coastal ecosystems. Our current understanding of the potential biological effects of metals in these ecosystems is limited. This study tested the transcriptional expression of immune- and stress-response genes in Sydney Rock oysters (Saccostrea glomerata). Oysters were exposed to four metals (cadmium, copper, lead and zinc) commonly associated with anthropogenic pollution in coastal waterways. Seven target genes (superoxide dismutase, ferritin, ficolin, defensin, HSP70, HSP90 and metallothionein) were selected. Quantitative (real-time) PCR analyses of the transcript expression of these genes showed that each of the different metals elicited unique transcriptional profiles. Significant changes in transcription were found for 18 of the 28 combinations tested (4 metals × 7 genes). Of these, 16 reflected down-regulation of gene transcription. HSP90 was the only gene significantly up-regulated by metal contamination (cadmium and zinc only), while defensin expression was significantly down-regulated by exposure to all four metals. This inhibition could have a significant negative effect on the oyster immune system, promoting susceptibility to opportunistic infections and disease.
authors.affiliation: Sydney Institute of Marine Science, Chowder Bay, NSW 2088, Australia; Department of Biological Sciences, Macquarie University, NSW 2109, Australia.
authors.forename: Daisy A
authors.initials: DA
authors.lastname: Taylor
authors.forename: Emma L
authors.initials: EL
authors.lastname: Thompson
authors.forename: Sham V
authors.initials: SV
authors.lastname: Nair
authors.forename: David A
authors.initials: DA
authors.lastname: Raftos
mesh_terms: D000818:Animals; D015536:Down-Regulation; D004784:Environmental Monitoring / Q000379:methods*; D015870:Gene Expression / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics; D007107:Immune System / Q000187:drug effects / Q000502:physiology; D008670:Metals / Q000633:toxicity*; D010125:Ostreidae; D013312:Stress, Physiological / Q000502:physiology; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D018841:HSP90 Heat-Shock Proteins; D008670:Metals; D014874:Water Pollutants, Chemical; D013482:Superoxide Dismutase