Project description:Diazotrophs provide the main source of reactive nitrogen to the ocean, sustaining primary productivity and CO2 uptake. Climate change is raising temperatures, decreasing pH and reducing nutrient availability. How microbes respond to these changes is largely unexplained. Similarly, the role of DOM in the growth and survival of certain diazotrophic organisms is poorly understood. Moreover, growing evidence indicates some diazotrophs are capable of utilizing distinct DOM compounds via osmotrophy providing them with additional metabolic plasticity and ecological advantages compared to other non-diazotrophic microbes. We aimed to understand how osmotrophy could modify carbon uptake and alleviate energy stress in diazotrophs under ongoing climate change perturbations. We hypothesized that Crocosphaera preferentially uses DOM when labile as a carbon source in present pH conditions, as compared to future more acidic scenarios with higher access to inorganic carbon. Alternatively, the lower pH may cause Crocosphaera to be energy limited when trying to maintain intracellular homeostasis which would favour DOM uptake as an extra source of energy.
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.
Project description:This SuperSeries is composed of the following subset Series: GSE38738: High contaminant loads in Lake Apopka mesocosms affect the ovarian transcriptome in largemouth bass [April] GSE38773: High contaminant loads in Lake Apopka mesocosms affect the ovarian transcriptome in largemouth bass [January] Refer to individual Series
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).