Project description:Lake Apopka (Fl, USA) experienced heavy uses of organochlorine pesticides (OCPs) in the 1950s-1970 during an intense agricultural period. As a result, the region remains heavily contaminated and was declared a Superfund site by the US Environmental Protection Agency. Aquatic organisms inhabit the freshwater systems in and around Lake Apopka, however the impacts of sub chronic exposure to OCPs in this natural environment are not known. The objectives of this study were to determine the effects of the contamination on the reproductive axis of largemouth bass (LMB) (Micropterus salmoides). In October (2007), healthy LMB were stocked into natural mesocosms and remained in mesocosms before being sampled in January 2008 (at early oogenesis). Additional LMB were placed into mesocosms for 2 months in February (2008) and sampled in April (2008) (oocyte maturation). LMB placed in these mesocosms for four months had a 2-20X higher contaminant load for OCPs (e.g. DDE, dieldrin, methoxychlor) than LMB collected from reference sites. Gonadosomatic index for LMB collected in April from the mesocosms were not different that LMB from reference sites. Vitellogenin levels in LMB collected from the mesocosms in January and April were not significantly different than fish collected from Welaka in late vitellogenin or early maturation respectively. Steroids were depressed in mesocosm fish. Microarray analysis revealed that the expression profiles of genes in the LMB ovary were unique compared to LMB collected form reference sites. Transcripts that showed altered abundance in LMB from the mesocosms were insulin-like growth factor I and steroidogenic acute regulatory protein. Interestingly, differentially expressed transcripts showed a significant and positive correlation for LMB sampled in January and April despite the 3 month period in between samplings. Sub-network enrichment analysis for cellular processes showed that retinoic acid metabolism and germ-cell development were decreased in mesocosm-exposed fish but processes such as vitellogenesis, amino acid catabolism, granulosa cell function, vitamin D metabolism, and hormone biosynthesis were increased in mesocosm-exposed fish. These data suggest that (1) LMB from the mesocosms are exhibiting unique gene profiles that may impair normal reproduction and that (2) microarray analysis in the field can provide site specific information by discriminating LMB from reference and polluted sites.

Project description:Lake Apopka (Fl, USA) experienced heavy uses of organochlorine pesticides (OCPs) in the 1950s-1970 during an intense agricultural period. As a result, the region remains heavily contaminated and was declared a Superfund site by the US Environmental Protection Agency. Aquatic organisms inhabit the freshwater systems in and around Lake Apopka, however the impacts of sub chronic exposure to OCPs in this natural environment are not known. The objectives of this study were to determine the effects of the contamination on the reproductive axis of largemouth bass (LMB) (Micropterus salmoides). In October (2007), healthy LMB were stocked into natural mesocosms and remained in mesocosms before being sampled in January 2008 (at early oogenesis). Additional LMB were placed into mesocosms for 2 months in February (2008) and sampled in April (2008) (oocyte maturation). LMB placed in these mesocosms for four months had a 2-20X higher contaminant load for OCPs (e.g. DDE, dieldrin, methoxychlor) than LMB collected from reference sites. Gonadosomatic index for LMB collected in April from the mesocosms were not different that LMB from reference sites. Vitellogenin levels in LMB collected from the mesocosms in January and April were not significantly different than fish collected from Welaka in late vitellogenin or early maturation respectively. Steroids were depressed in mesocosm fish. Microarray analysis revealed that the expression profiles of genes in the LMB ovary were unique compared to LMB collected form reference sites. Transcripts that showed altered abundance in LMB from the mesocosms were insulin-like growth factor I and steroidogenic acute regulatory protein. Interestingly, differentially expressed transcripts showed a significant and positive correlation for LMB sampled in January and April despite the 3 month period in between samplings. Sub-network enrichment analysis for cellular processes showed that retinoic acid metabolism and germ-cell development were decreased in mesocosm-exposed fish but processes such as vitellogenesis, amino acid catabolism, granulosa cell function, vitamin D metabolism, and hormone biosynthesis were increased in mesocosm-exposed fish. These data suggest that (1) LMB from the mesocosms are exhibiting unique gene profiles that may impair normal reproduction and that (2) microarray analysis in the field can provide site specific information by discriminating LMB from reference and polluted sites. 12 microarrays on LMB collected from the wild in January. These include St John River (n=4), DeLeon Springs (n = 4), and animals placed in Apopka mesocosms (n=4).

Project description:Lake Apopka (Fl, USA) experienced heavy uses of organochlorine pesticides (OCPs) in the 1950s-1970 during an intense agricultural period. As a result, the region remains heavily contaminated and was declared a Superfund site by the US Environmental Protection Agency. Aquatic organisms inhabit the freshwater systems in and around Lake Apopka, however the impacts of sub chronic exposure to OCPs in this natural environment are not known. The objectives of this study were to determine the effects of the contamination on the reproductive axis of largemouth bass (LMB) (Micropterus salmoides). In October (2007), healthy LMB were stocked into natural mesocosms and remained in mesocosms before being sampled in January 2008 (at early oogenesis). Additional LMB were placed into mesocosms for 2 months in February (2008) and sampled in April (2008) (oocyte maturation). LMB placed in these mesocosms for four months had a 2-20X higher contaminant load for OCPs (e.g. DDE, dieldrin, methoxychlor) than LMB collected from reference sites. Gonadosomatic index for LMB collected in April from the mesocosms were not different that LMB from reference sites. Vitellogenin levels in LMB collected from the mesocosms in January and April were not significantly different than fish collected from Welaka in late vitellogenin or early maturation respectively. Steroids were depressed in mesocosm fish. Microarray analysis revealed that the expression profiles of genes in the LMB ovary were unique compared to LMB collected form reference sites. Transcripts that showed altered abundance in LMB from the mesocosms were insulin-like growth factor I and steroidogenic acute regulatory protein. Interestingly, differentially expressed transcripts showed a significant and positive correlation for LMB sampled in January and April despite the 3 month period in between samplings. Sub-network enrichment analysis for cellular processes showed that retinoic acid metabolism and germ-cell development were decreased in mesocosm-exposed fish but processes such as vitellogenesis, amino acid catabolism, granulosa cell function, vitamin D metabolism, and hormone biosynthesis were increased in mesocosm-exposed fish. These data suggest that (1) LMB from the mesocosms are exhibiting unique gene profiles that may impair normal reproduction and that (2) microarray analysis in the field can provide site specific information by discriminating LMB from reference and polluted sites. 8 microarrays on LMB collected from the wild in April. These include St John River (n=4) and animals placed in Apopka mesocosms (n=4).

Project description:Our main objectives were: 1) to identify transcriptional signatures specific to the exposure to two metals: Ni and Cd; 2) to investigate the mechanisms of toxicity for these two metals; and 3) to develop a predictive tool to identify the sublethal effects of Ni and Cd contaminants in fish sampled from natural environments. The molecular mechanisms underlying nickel (Ni) and cadmium (Cd) toxicity and their specific effects on fish are poorly understood. Documenting gene transcription profiles offers a powerful approach towards identifying the molecular mechanisms affected by these metals and to discover biomarkers of their toxicity. However, confounding environmental factors can complicate the interpretation of the results and the detection of biomarkers for fish captured in their natural environment. In the present study, a 1000 candidate-gene microarray, developed from a previous RNA-seq study on a subset of individual fish from contrasting level of metal contamination, was used to investigate the transcriptional response to metal (Ni and Cd) and non metal (temperature, oxygen, and diet) stressors in yellow perch (Perca flavescens). Specifically, we aimed at 1) identifying transcriptional signatures specific to Ni and Cd exposure, 2) investigating the mechanisms of their toxicity, and 3) developing a predictive tool to identify the sublethal effects of Ni and Cd contaminants in fish sampled from natural environments. A total of 479 genes displayed significantly different transcription levels when temperature varied while 287 and 177 genes were differentially transcribed at different concentrations of Ni and Cd, respectively. These metals were found to mainly affect the transcription level of genes involved in iron metabolism, transcriptional and translational processes, vitamin metabolism, blood coagulation, and calcium transport. In addition, a linear discriminant analysis (LDA) made using gene transcription levels yielded 94% correctly reassigned samples regarding their level of metal contamination, which indicates the potential of the microarray to detect perch response to Cd or Ni effects. Comparison between fish exposed to three temperatures (11, 20, 28M-BM-0C) using a loop design, comparison between control fish and fich exposed to restrictive diet using a pairwise design, comparison between fish exposed to hypoxia and control fish, comparison between fish exposed to two concentrations of cadmium and control fish using a loop design, and comparison between fish exposed to two concentrations of nickel and control fish using a loop design.

Dataset Information

Transcriptional response of yellow perch to changes in ambient metal concentrations - a reciprocal field transplantation experiment

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