Project description:Transcriptional profiling of mussel (Mytilus galloprovincialis) digestive gland tissue comparing control tissue with tissue obtained from animals exposed to sublethal amounts of Chlorpyrifos, animals injected into the posterior adductor muscle with 25 pico-moles 17β-estradiol (E2) and animals pre-exposed for three days to the pesticide and further injected with E2. Background: Many pesticides have been shown to act as endocrine disrupters. Although the potencies of currently used pesticides as hormone agonists/antagonists in vitro are low compared with those of natural ligands, their ability to act via multiple mechanisms might enhance the biological effect. The organophosphate Chlorpyrifos (CHP) has been shown to be weakly estrogenic and cause adverse neurodevelopmental effects in mammals. However, no information is available on the possible endocrine effects of CHP in aquatic organisms. In the digestive gland of the bivalve Mytilus galloprovincialis, a target tissue for the action of both estrogens and pesticides, the possible effects of CHP on the responses to the natural estrogen 17β-estradiol (E2) were investigated. Methodology/Principal findings: Mussels were exposed to CHP (4.5 mg/l, 72 hrs) and subsequently injected with E2 (6.75 ng/g dw). Responses were evaluated in CHP, E2 and CHP/E2 treatment groups at 24 h p.i. by a biomarker/transcriptomic approach. CHP and E2 induced additive, synergistic, and antagonistic effects on lysosomal biomarkers (lysosomal membrane stability, lysosome/cytoplasm volume ratio, lipofuscin and neutral lipid accumulation). Additive and synergistic effects were also observed on the expression of estrogen-responsive genes (GSTπ, catalase and 5-HTR) evaluated by RT-Q-PCR. The use of a 1.7K cDNA Mytilus microarray showed that CHP, E2 and CHP/E2, induced 81, 44, and 65 Differentially Expressed Genes (DEGs), respectively. 24 genes were exclusively shared between CHP and CHP/E2, only 2 genes between E2 and CHP/E2. Moreover, 36 genes were uniquely modulated by CHP/E2. Gene ontology annotation was used to elucidate the putative mechanisms involved in the responses elicited by different treatments. Conclusions: The results show complex interactions between CHP and E2 in mussel digestive gland, indicating that the combination of certain pesticides and hormones may give rise to unexpected effects at the molecular/cellular level. Overall, these data demonstrate that CHP can interfere with the mussel responses to natural estrogens. Four-condition experiment. Dual color competitive hybridizations. Common reference (vehicle treated animals, 0.02% Dimethyl sulfoxide, injected with 50 μl of a solution of Artificial Sea Water containing 0.05 % ethanol); Pools of six animals. Biological replicates: 4 controls, 4 Chlorpyrifos, 4 17β-estradiol, 4 Chlorpyrifos-17β-stradiol. One replicate per array.

Project description:Transcriptional profiling of mussel (Mytilus galloprovincialis) digestive gland tissue comparing control tissue with tissue obtained from animals exposed to sublethal amounts of Chlorpyrifos, animals injected into the posterior adductor muscle with 25 pico-moles 17β-estradiol (E2) and animals pre-exposed for three days to the pesticide and further injected with E2. Background: Many pesticides have been shown to act as endocrine disrupters. Although the potencies of currently used pesticides as hormone agonists/antagonists in vitro are low compared with those of natural ligands, their ability to act via multiple mechanisms might enhance the biological effect. The organophosphate Chlorpyrifos (CHP) has been shown to be weakly estrogenic and cause adverse neurodevelopmental effects in mammals. However, no information is available on the possible endocrine effects of CHP in aquatic organisms. In the digestive gland of the bivalve Mytilus galloprovincialis, a target tissue for the action of both estrogens and pesticides, the possible effects of CHP on the responses to the natural estrogen 17β-estradiol (E2) were investigated. Methodology/Principal findings: Mussels were exposed to CHP (4.5 mg/l, 72 hrs) and subsequently injected with E2 (6.75 ng/g dw). Responses were evaluated in CHP, E2 and CHP/E2 treatment groups at 24 h p.i. by a biomarker/transcriptomic approach. CHP and E2 induced additive, synergistic, and antagonistic effects on lysosomal biomarkers (lysosomal membrane stability, lysosome/cytoplasm volume ratio, lipofuscin and neutral lipid accumulation). Additive and synergistic effects were also observed on the expression of estrogen-responsive genes (GSTπ, catalase and 5-HTR) evaluated by RT-Q-PCR. The use of a 1.7K cDNA Mytilus microarray showed that CHP, E2 and CHP/E2, induced 81, 44, and 65 Differentially Expressed Genes (DEGs), respectively. 24 genes were exclusively shared between CHP and CHP/E2, only 2 genes between E2 and CHP/E2. Moreover, 36 genes were uniquely modulated by CHP/E2. Gene ontology annotation was used to elucidate the putative mechanisms involved in the responses elicited by different treatments. Conclusions: The results show complex interactions between CHP and E2 in mussel digestive gland, indicating that the combination of certain pesticides and hormones may give rise to unexpected effects at the molecular/cellular level. Overall, these data demonstrate that CHP can interfere with the mussel responses to natural estrogens.

Project description:Transcriptional profiling of the mantle tissue across the four stages of male gonads development (winter peak) in a natural population of the marine mussel Mytilus galloprovincialis sampled in the Bizerta Lagoon, Tunisia, across November 2007 -March 2008. Background: Seasonal environmental changes may affect the physiology of Mytilus galloprovincialis (Lam.), an intertidal filter-feeder bivalve occurring commonly in Mediterranean and Atlantic coastal areas. We investigated seasonal variations in relative transcript abundance of the digestive gland and the mantle (gonads) of males and females. To identify gene expression trends, we used a medium-density cDNA microarray (1.7 K probes) in dual-color competitive hybridization analyses. Results: Hierarchical clustering of digestive gland microarray data showed two main branches, distinguishing profiles associated with the M-bM-^@M-^\hotM-bM-^@M-^] months (MayM-bM-^@M-^SAugust) from the other months. Genes involved in chitin metabolism, associated with mussel nutrition and digestion, showed higher expression during summer. Moreover, we found different gene expression patterns in the digestive glands of males and females during the four stages of mussel gonadal development. Microarray data from gonadal transcripts also displayed clear patterns during the different developmental phases with peak relative mRNA abundance at the ripe phase (stage III) for both sexes. Conclusion: These data showed a clear temporal pattern in gene expression profiles of mussels sampled over an annual cycle. Physiological response to thermal variation, food availability, and reproductive status across months may contribute to variation in gene expression. Mantle tissue from individual animals in different gonad maturation stages were analyzed in a complete loop design. Dual color competitive hybridizations (stage 4 vs stage 1, 2 vs 1, 3 vs 2, 4 vs 3) including label swap. Single individuals. Four biological replicates. One replicate per array.

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Mytilus galloprovincialis

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