Robert Griffitt - Academia.edu (original) (raw)

Papers by Robert Griffitt

Research paper thumbnail of Simultaneous exposure to chronic hypoxia and dissolved PAHs results in reduced egg production and larval survival in the Sheepshead minnow (Cyprinodon variegatus)

Environmental Toxicology and Chemistry, 2015

Estuarine fish in the northern Gulf of Mexico are annually exposed to hypoxic conditions. In addi... more Estuarine fish in the northern Gulf of Mexico are annually exposed to hypoxic conditions. In addition to hypoxia, fish located throughout the northern Gulf of Mexico were potentially exposed to oil released during the Deepwater Horizon incident. Therefore; the interaction between oil exposure and hypoxia is worthy of investigation. To examine this interaction, we exposed adult and larval Sheepshead minnow (Cyprinodon variegatus, SHM) to crude or dispersed oil under both normoxic and hypoxic conditions. We examined total egg production, egg hatching success, and larval survival post hatch. Our results indicate that co-exposure to crude or dispersed oil and hypoxia resulted in a significant decrease in egg production, as well as a significant decrease in both egg hatch success and larval survival post hatch. The significant impact on reproductive success following crude or dispersed oil and hypoxia exposure indicates the importance of including environmental parameters such as hypoxia when evaluating the impact of an oil spill. This article is protected by copyright. All rights reserved.

Research paper thumbnail of Impacts of the Deepwater Horizon Oil Spill on the Reproductive Biology of Spotted Seatrout (Cynoscion nebulosus)

Research paper thumbnail of Queen Conch (Strombus gigas) Testis Regresses during the Reproductive Season at Nearshore Sites in the Florida Keys

PLoS ONE, 2010

Queen conch (Strombus gigas) reproduction is inhibited in nearshore areas of the Florida Keys, re... more Queen conch (Strombus gigas) reproduction is inhibited in nearshore areas of the Florida Keys, relative to the offshore environment where conchs reproduce successfully. Nearshore reproductive failure is possibly a result of exposure to environmental factors, including heavy metals, which are likely to accumulate close to shore. Metals such as Cu and Zn are detrimental to reproduction in many mollusks. Histology shows gonadal atrophy in nearshore conchs as compared to reproductively healthy offshore conchs. In order to determine molecular mechanisms leading to tissue changes and reproductive failure, a microarray was developed. A normalized cDNA library for queen conch was constructed and sequenced using the 454 Life Sciences GS-FLX pyrosequencer, producing 27,723 assembled contigs and 7,740 annotated transcript sequences. The resulting sequences were used to design the microarray. Microarray analysis of conch testis indicated differential regulation of 255 genes (p<0.01) in nearshore conch, relative to offshore. Changes in expression for three of four transcripts of interest were confirmed using real-time reverse transcription polymerase chain reaction. Gene Ontology enrichment analysis indicated changes in biological processes: respiratory chain (GO:0015992), spermatogenesis (GO:0007283), small GTPase-mediated signal transduction (GO:0007264), and others. Inductively coupled plasma-mass spectrometry analysis indicated that Zn and possibly Cu were elevated in some nearshore conch tissues. Congruence between testis histology and microarray data suggests that nearshore conch testes regress during the reproductive season, while offshore conch testes develop normally. Possible mechanisms underlying the testis regression observed in queen conch in the nearshore Florida Keys include a disruption of small GTPase (Ras)-mediated signaling in testis development. Additionally, elevated tissue levels of Cu (34.77 ng/mg in testis) and Zn (831.85 ng/mg in digestive gland, 83.96 ng/mg in testis) nearshore are similar to reported levels resulting in reproductive inhibition in other gastropods, indicating that these metals possibly contribute to NS conch reproductive failure.

Research paper thumbnail of Construction of a robust microarray from a non-model species largemouth bass, Micropterus salmoides (Lacèpede), using pyrosequencing technology

Journal of Fish Biology, 2008

A novel custom microarray for largemouth bass (Micropterus salmoides) was designed with sequences... more A novel custom microarray for largemouth bass (Micropterus salmoides) was designed with sequences obtained from a normalized cDNA library using the 454 Life Sciences GS-20 pyrosequencer. This approach yielded in excess of 58 million bases of high-quality sequence. The sequence information was combined with 2,616 reads obtained by traditional suppressive subtractive hybridizations to derive a total of 31,391 unique sequences. Annotation and coding sequences were predicted for these transcripts where possible. 16,350 annotated transcripts were selected as target sequences for the design of the custom largemouth bass oligonucleotide microarray. The microarray was validated by examining the transcriptomic response in male largemouth bass exposed to 17βoestradiol. Transcriptomic responses were assessed in liver and gonad, and indicated gene expression profiles typical of exposure to oestradiol. The results demonstrate the potential to rapidly create the tools necessary to assess large scale transcriptional responses in non-model species, paving the way for expanded impact of toxicogenomics in ecotoxicology.

Research paper thumbnail of SERIAL ANALYSIS OF GENE EXPRESSION REVEALS IDENTIFIABLE PATTERNS IN TRANSCRIPTOME PROFILES OF PALAEMONETES PUGIO EXPOSED TO THREE COMMON ENVIRONMENTAL STRESSORS

Environmental Toxicology and Chemistry, 2007

Serial analysis of gene expression (SAGE) is a transcriptome-profiling technique that allows accu... more Serial analysis of gene expression (SAGE) is a transcriptome-profiling technique that allows accurate gene expression profiles to be generated without any need for prior sequence knowledge, making it ideal for assaying toxicant-specific genetic responses in nonmodel species. We used SAGE to perform a large-scale survey of the Palaemonetes pugio transcriptome under different chemical xenobiotic stresses. Four libraries were constructed from fipronil-exposed, endosulfan-exposed, and cadmiumexposed shrimp, as well as from carrier-control-exposed shrimp. A total of 37,152 tags were sequenced from the four libraries, including 13,754 unique tags. Statistical analysis revealed that 117 tags were differentially expressed significantly in at least one of the three exposures. Cluster analyses of the altered tags showed that fipronil and endosulfan elicit transcriptome profiles that are more similar to each other than either one was to cadmium. Quantitative polymerase chain reaction (QPCR) was performed on a subset of 46 differentially expressed tags, and largely confirmed the SAGE results. The tags were filtered to identify tags for which both SAGE and QPCR agreed in regard to the direction and magnitude of affect, and which were informative about the exposure experienced. A subset of 16 tags was identified that represents a putative biomarker suite that is indicative of exposures to the three toxicants.

Research paper thumbnail of EFFECTS OF PARTICLE COMPOSITION AND SPECIES ON TOXICITY OF METALLIC NANOMATERIALS IN AQUATIC ORGANISMS

Environmental Toxicology and Chemistry, 2008

Metallic nanoparticles are among the most widely used types of engineered nanomaterials; however,... more Metallic nanoparticles are among the most widely used types of engineered nanomaterials; however, little is known about their environmental fate and effects. To assess potential environmental effects of engineered nanometals, it is important to determine which species are sensitive to adverse effects of various nanomaterials. In the present study, zebrafish, daphnids, and an algal species were used as models of various trophic levels and feeding strategies. To understand whether observed effects are caused by dissolution, particles were characterized before testing, and particle concentration and dissolution were determined during exposures. Organisms were exposed to silver, copper, aluminum, nickel, and cobalt as both nanoparticles and soluble salts as well as to titanium dioxide nanoparticles. Our results indicate that nanosilver and nanocopper cause toxicity in all organisms tested, with 48-h median lethal concentrations as low as 40 and 60 g/L, respectively, in Daphnia pulex adults, whereas titanium dioxide did not cause toxicity in any of the tests. Susceptibility to nanometal toxicity differed among species, with filter-feeding invertebrates being markedly more susceptible to nanometal exposure compared with larger organisms (i.e., zebrafish). The role of dissolution in observed toxicity also varied, being minor for silver and copper but, apparently, accounting for most of the toxicity with nickel. Nanoparticulate forms of metals were less toxic than soluble forms based on mass added, but other dose metrics should be developed to accurately assess concentration-response relationships for nanoparticle exposures.

Research paper thumbnail of Serial Analysis of Gene Expression (SAGE) reveals identifiable patterns in transcriptome profiles of Palaemonetes pugio exposed to three common environmental stressors

Environmental Toxicology and Chemistry, 2007

Research paper thumbnail of Exposure to Copper Nanoparticles Causes Gill Injury and Acute Lethality in Zebrafish ( Danio rerio )

Environmental Science & Technology, 2007

Increasing use of metallic nanomaterials is likely to result in release of these particles into a... more Increasing use of metallic nanomaterials is likely to result in release of these particles into aqueous environments; however, it is unclear if these materials present a hazard to aquatic organisms. Because some dissolution of metal particles will occur, it is important to distinguish effects of nanoparticulates from dissolved metals. To address this issue, acute toxicity of soluble copper and 80 nm copper nanoparticle suspensions were examined in zebrafish. The results demonstrate that nanocopper is acutely toxic to zebrafish, with a 48 h LC50 concentration of 1.5 mg/L. Rapid aggregation of copper nanoparticles occurred after suspension in water, resulting in 50-60% of added mass leaving the water column. While dissolution of particulate copper occurred, it was insufficient to explain the mortality in nanocopper exposures. Histological and biochemical analysis revealed that the gill was the primary target organ for nanocopper. To further investigate the effects of nanocopper on the gill, zebrafish were exposed to 100 microg/L of nanocopper or to the concentration of soluble copper matching that present due to dissolution of the particles. Under these conditions, nanocopper produced different morphological effects and global gene expression patterns in the gill than soluble copper, clearly demonstrating that the effects of nanocopper on gill are not mediated solely by dissolution.

Research paper thumbnail of Cathepsin B and Glutathione Peroxidase Show Differing Transcriptional Responses in the Grass Shrimp, Palaemonetes pugio Following Exposure to Three Xenobiotics

Environmental Science & Technology, 2006

The common molecular biology techniques, suppressive-subtractive hybridization (SSH) and semi-qua... more The common molecular biology techniques, suppressive-subtractive hybridization (SSH) and semi-quantitative real-time PCR (SQRT-PCR), were used to identify differentially expressed genes in the grass shrimp, Palaemonetes pugio following exposure to three different xenobiotics. Lab-acclimated adult male grass shrimp were exposed to empirically derived 96-hr male-specific LC50 concentrations of fipronil (FP, a phenylpyrazole GABA disrupting pesticide), endosulfan (ES, a cyclodiene GABA disrupting pesticide), or cadmium (Cd), as well as a control (CC). An SSH gene expression library was constructed from surviving shrimp from the fipronil and control exposures. Clones obtained by SSH were identified by searching against the NCBI website. A total of 42 genes were identified that were up-regulated by FP exposure, and 47 that were down-regulated. A subset of the affected genes was tested with SQRT-PCR to verify responsiveness to fipronil, as well as to endosulfan and cadmium. Two genes showed strong and significant responses to the exposures: glutathione peroxidase was significantly up-regulated by all three exposures, while Cathepsin B was strongly responsive to the two pesticides, but not to cadmium.

Research paper thumbnail of Chronic nanoparticulate silver exposure results in tissue accumulation and transcriptomic changes in zebrafish

Aquatic Toxicology, 2013

Increasing utilization of metallic nanomaterials in recent years implies an increasing rate of re... more Increasing utilization of metallic nanomaterials in recent years implies an increasing rate of release to the environment, with potentially serious adverse effects on environmentally important species. Previously, we demonstrated that exposure to nanoparticulate silver for 24-48 h results in dramatic alterations in global gene expression patterns and increased tissue burdens in zebrafish gills. The present study reports outcomes associated with chronic exposure to nanoparticulate silver in zebrafish. Adult female Danio rerio were exposed to 5, 15, 25, or 50 μg/L nanoparticulate silver in a time course up to 28 days. A soluble silver treatment (5 μg/L) was also included. Results indicate that use of flow-through systems for chronic nanometal studies is a viable concept; measured concentrations of approximately 60% of nominal values over the course of the 28-day exposure were observed. Dissolution of nanoparticulate silver was measured twice weekly throughout the exposure ranging between 0.5 and 1.0 μg/L, and was relatively consistent between nanoparticulate silver tanks, with no differences between treatments. Gill samples from the 28-day time point were analyzed for global gene expression patterns and histopathology. Tissue accumulation in both gill and eviscerated carcass was dose-dependent, and remained elevated 4 days after the silver was removed. Microarray analysis also revealed a dose-dependent response pattern, with the largest number of genes affected in the 50 μg/L AgNP exposure. Pathway analysis of affected genes identified a number of GO terms that were significantly over-represented in the high AgNP dataset. These terms are associated with DNA damage repair, cellular restructuring, and developmental processes.

Research paper thumbnail of Photo-induced toxicity of Deepwater Horizon slick oil to blue crab ( Callinectes sapidus ) larvae

Environmental Toxicology and Chemistry, 2015

The 2010 Deepwater Horizon oil spill resulted in the accidental release of approximately 700 mill... more The 2010 Deepwater Horizon oil spill resulted in the accidental release of approximately 700 million L of crude oil into the Gulf of Mexico. Photo-induced toxicity after co-exposure to ultraviolet (UV) radiation is 1 mechanism by which polycyclic aromatic hydrocarbons (PAHs) from oil spills may exert toxicity. Blue crab are an important commercial and ecological resource in the Gulf of Mexico, and their largely transparent larvae may make them sensitive to PAH photo-induced toxicity. The goal of the present study was to examine the sensitivity of early lifestage blue crab (Callinectes sapidus) zoea to slick oil collected during the Deepwater Horizon spill. Blue crab zoea were exposed to 1 of several dilutions of water accommodated fractions from 1 of 2 sources of oil and gradations of natural sunlight in a factorial design. Two 7-h solar exposures were carried out with a recovery period (dark) in between. Survival was found to be UV- and PAH-dependent. Toxicity was observed within the range of surface PAH concentrations reported in the Gulf of Mexico during the Deepwater Horizon spill. These findings indicate that early lifestage blue crab are sensitive to photo-induced toxicity from Deepwater Horizon slick oil. Environ Toxicol Chem 2015;9999:1-6. © 2015 SETAC.

Research paper thumbnail of Simultaneous exposure to chronic hypoxia and dissolved PAHs results in reduced egg production and larval survival in the Sheepshead minnow (Cyprinodon variegatus)

Environmental Toxicology and Chemistry, 2015

Estuarine fish in the northern Gulf of Mexico are annually exposed to hypoxic conditions. In addi... more Estuarine fish in the northern Gulf of Mexico are annually exposed to hypoxic conditions. In addition to hypoxia, fish located throughout the northern Gulf of Mexico were potentially exposed to oil released during the Deepwater Horizon incident. Therefore; the interaction between oil exposure and hypoxia is worthy of investigation. To examine this interaction, we exposed adult and larval Sheepshead minnow (Cyprinodon variegatus, SHM) to crude or dispersed oil under both normoxic and hypoxic conditions. We examined total egg production, egg hatching success, and larval survival post hatch. Our results indicate that co-exposure to crude or dispersed oil and hypoxia resulted in a significant decrease in egg production, as well as a significant decrease in both egg hatch success and larval survival post hatch. The significant impact on reproductive success following crude or dispersed oil and hypoxia exposure indicates the importance of including environmental parameters such as hypoxia when evaluating the impact of an oil spill. This article is protected by copyright. All rights reserved.

Research paper thumbnail of Impacts of the Deepwater Horizon Oil Spill on the Reproductive Biology of Spotted Seatrout (Cynoscion nebulosus)

Research paper thumbnail of Queen Conch (Strombus gigas) Testis Regresses during the Reproductive Season at Nearshore Sites in the Florida Keys

PLoS ONE, 2010

Queen conch (Strombus gigas) reproduction is inhibited in nearshore areas of the Florida Keys, re... more Queen conch (Strombus gigas) reproduction is inhibited in nearshore areas of the Florida Keys, relative to the offshore environment where conchs reproduce successfully. Nearshore reproductive failure is possibly a result of exposure to environmental factors, including heavy metals, which are likely to accumulate close to shore. Metals such as Cu and Zn are detrimental to reproduction in many mollusks. Histology shows gonadal atrophy in nearshore conchs as compared to reproductively healthy offshore conchs. In order to determine molecular mechanisms leading to tissue changes and reproductive failure, a microarray was developed. A normalized cDNA library for queen conch was constructed and sequenced using the 454 Life Sciences GS-FLX pyrosequencer, producing 27,723 assembled contigs and 7,740 annotated transcript sequences. The resulting sequences were used to design the microarray. Microarray analysis of conch testis indicated differential regulation of 255 genes (p<0.01) in nearshore conch, relative to offshore. Changes in expression for three of four transcripts of interest were confirmed using real-time reverse transcription polymerase chain reaction. Gene Ontology enrichment analysis indicated changes in biological processes: respiratory chain (GO:0015992), spermatogenesis (GO:0007283), small GTPase-mediated signal transduction (GO:0007264), and others. Inductively coupled plasma-mass spectrometry analysis indicated that Zn and possibly Cu were elevated in some nearshore conch tissues. Congruence between testis histology and microarray data suggests that nearshore conch testes regress during the reproductive season, while offshore conch testes develop normally. Possible mechanisms underlying the testis regression observed in queen conch in the nearshore Florida Keys include a disruption of small GTPase (Ras)-mediated signaling in testis development. Additionally, elevated tissue levels of Cu (34.77 ng/mg in testis) and Zn (831.85 ng/mg in digestive gland, 83.96 ng/mg in testis) nearshore are similar to reported levels resulting in reproductive inhibition in other gastropods, indicating that these metals possibly contribute to NS conch reproductive failure.

Research paper thumbnail of Construction of a robust microarray from a non-model species largemouth bass, Micropterus salmoides (Lacèpede), using pyrosequencing technology

Journal of Fish Biology, 2008

A novel custom microarray for largemouth bass (Micropterus salmoides) was designed with sequences... more A novel custom microarray for largemouth bass (Micropterus salmoides) was designed with sequences obtained from a normalized cDNA library using the 454 Life Sciences GS-20 pyrosequencer. This approach yielded in excess of 58 million bases of high-quality sequence. The sequence information was combined with 2,616 reads obtained by traditional suppressive subtractive hybridizations to derive a total of 31,391 unique sequences. Annotation and coding sequences were predicted for these transcripts where possible. 16,350 annotated transcripts were selected as target sequences for the design of the custom largemouth bass oligonucleotide microarray. The microarray was validated by examining the transcriptomic response in male largemouth bass exposed to 17βoestradiol. Transcriptomic responses were assessed in liver and gonad, and indicated gene expression profiles typical of exposure to oestradiol. The results demonstrate the potential to rapidly create the tools necessary to assess large scale transcriptional responses in non-model species, paving the way for expanded impact of toxicogenomics in ecotoxicology.

Research paper thumbnail of SERIAL ANALYSIS OF GENE EXPRESSION REVEALS IDENTIFIABLE PATTERNS IN TRANSCRIPTOME PROFILES OF PALAEMONETES PUGIO EXPOSED TO THREE COMMON ENVIRONMENTAL STRESSORS

Environmental Toxicology and Chemistry, 2007

Serial analysis of gene expression (SAGE) is a transcriptome-profiling technique that allows accu... more Serial analysis of gene expression (SAGE) is a transcriptome-profiling technique that allows accurate gene expression profiles to be generated without any need for prior sequence knowledge, making it ideal for assaying toxicant-specific genetic responses in nonmodel species. We used SAGE to perform a large-scale survey of the Palaemonetes pugio transcriptome under different chemical xenobiotic stresses. Four libraries were constructed from fipronil-exposed, endosulfan-exposed, and cadmiumexposed shrimp, as well as from carrier-control-exposed shrimp. A total of 37,152 tags were sequenced from the four libraries, including 13,754 unique tags. Statistical analysis revealed that 117 tags were differentially expressed significantly in at least one of the three exposures. Cluster analyses of the altered tags showed that fipronil and endosulfan elicit transcriptome profiles that are more similar to each other than either one was to cadmium. Quantitative polymerase chain reaction (QPCR) was performed on a subset of 46 differentially expressed tags, and largely confirmed the SAGE results. The tags were filtered to identify tags for which both SAGE and QPCR agreed in regard to the direction and magnitude of affect, and which were informative about the exposure experienced. A subset of 16 tags was identified that represents a putative biomarker suite that is indicative of exposures to the three toxicants.

Research paper thumbnail of EFFECTS OF PARTICLE COMPOSITION AND SPECIES ON TOXICITY OF METALLIC NANOMATERIALS IN AQUATIC ORGANISMS

Environmental Toxicology and Chemistry, 2008

Metallic nanoparticles are among the most widely used types of engineered nanomaterials; however,... more Metallic nanoparticles are among the most widely used types of engineered nanomaterials; however, little is known about their environmental fate and effects. To assess potential environmental effects of engineered nanometals, it is important to determine which species are sensitive to adverse effects of various nanomaterials. In the present study, zebrafish, daphnids, and an algal species were used as models of various trophic levels and feeding strategies. To understand whether observed effects are caused by dissolution, particles were characterized before testing, and particle concentration and dissolution were determined during exposures. Organisms were exposed to silver, copper, aluminum, nickel, and cobalt as both nanoparticles and soluble salts as well as to titanium dioxide nanoparticles. Our results indicate that nanosilver and nanocopper cause toxicity in all organisms tested, with 48-h median lethal concentrations as low as 40 and 60 g/L, respectively, in Daphnia pulex adults, whereas titanium dioxide did not cause toxicity in any of the tests. Susceptibility to nanometal toxicity differed among species, with filter-feeding invertebrates being markedly more susceptible to nanometal exposure compared with larger organisms (i.e., zebrafish). The role of dissolution in observed toxicity also varied, being minor for silver and copper but, apparently, accounting for most of the toxicity with nickel. Nanoparticulate forms of metals were less toxic than soluble forms based on mass added, but other dose metrics should be developed to accurately assess concentration-response relationships for nanoparticle exposures.

Research paper thumbnail of Serial Analysis of Gene Expression (SAGE) reveals identifiable patterns in transcriptome profiles of Palaemonetes pugio exposed to three common environmental stressors

Environmental Toxicology and Chemistry, 2007

Research paper thumbnail of Exposure to Copper Nanoparticles Causes Gill Injury and Acute Lethality in Zebrafish ( Danio rerio )

Environmental Science & Technology, 2007

Increasing use of metallic nanomaterials is likely to result in release of these particles into a... more Increasing use of metallic nanomaterials is likely to result in release of these particles into aqueous environments; however, it is unclear if these materials present a hazard to aquatic organisms. Because some dissolution of metal particles will occur, it is important to distinguish effects of nanoparticulates from dissolved metals. To address this issue, acute toxicity of soluble copper and 80 nm copper nanoparticle suspensions were examined in zebrafish. The results demonstrate that nanocopper is acutely toxic to zebrafish, with a 48 h LC50 concentration of 1.5 mg/L. Rapid aggregation of copper nanoparticles occurred after suspension in water, resulting in 50-60% of added mass leaving the water column. While dissolution of particulate copper occurred, it was insufficient to explain the mortality in nanocopper exposures. Histological and biochemical analysis revealed that the gill was the primary target organ for nanocopper. To further investigate the effects of nanocopper on the gill, zebrafish were exposed to 100 microg/L of nanocopper or to the concentration of soluble copper matching that present due to dissolution of the particles. Under these conditions, nanocopper produced different morphological effects and global gene expression patterns in the gill than soluble copper, clearly demonstrating that the effects of nanocopper on gill are not mediated solely by dissolution.

Research paper thumbnail of Cathepsin B and Glutathione Peroxidase Show Differing Transcriptional Responses in the Grass Shrimp, Palaemonetes pugio Following Exposure to Three Xenobiotics

Environmental Science & Technology, 2006

The common molecular biology techniques, suppressive-subtractive hybridization (SSH) and semi-qua... more The common molecular biology techniques, suppressive-subtractive hybridization (SSH) and semi-quantitative real-time PCR (SQRT-PCR), were used to identify differentially expressed genes in the grass shrimp, Palaemonetes pugio following exposure to three different xenobiotics. Lab-acclimated adult male grass shrimp were exposed to empirically derived 96-hr male-specific LC50 concentrations of fipronil (FP, a phenylpyrazole GABA disrupting pesticide), endosulfan (ES, a cyclodiene GABA disrupting pesticide), or cadmium (Cd), as well as a control (CC). An SSH gene expression library was constructed from surviving shrimp from the fipronil and control exposures. Clones obtained by SSH were identified by searching against the NCBI website. A total of 42 genes were identified that were up-regulated by FP exposure, and 47 that were down-regulated. A subset of the affected genes was tested with SQRT-PCR to verify responsiveness to fipronil, as well as to endosulfan and cadmium. Two genes showed strong and significant responses to the exposures: glutathione peroxidase was significantly up-regulated by all three exposures, while Cathepsin B was strongly responsive to the two pesticides, but not to cadmium.

Research paper thumbnail of Chronic nanoparticulate silver exposure results in tissue accumulation and transcriptomic changes in zebrafish

Aquatic Toxicology, 2013

Increasing utilization of metallic nanomaterials in recent years implies an increasing rate of re... more Increasing utilization of metallic nanomaterials in recent years implies an increasing rate of release to the environment, with potentially serious adverse effects on environmentally important species. Previously, we demonstrated that exposure to nanoparticulate silver for 24-48 h results in dramatic alterations in global gene expression patterns and increased tissue burdens in zebrafish gills. The present study reports outcomes associated with chronic exposure to nanoparticulate silver in zebrafish. Adult female Danio rerio were exposed to 5, 15, 25, or 50 μg/L nanoparticulate silver in a time course up to 28 days. A soluble silver treatment (5 μg/L) was also included. Results indicate that use of flow-through systems for chronic nanometal studies is a viable concept; measured concentrations of approximately 60% of nominal values over the course of the 28-day exposure were observed. Dissolution of nanoparticulate silver was measured twice weekly throughout the exposure ranging between 0.5 and 1.0 μg/L, and was relatively consistent between nanoparticulate silver tanks, with no differences between treatments. Gill samples from the 28-day time point were analyzed for global gene expression patterns and histopathology. Tissue accumulation in both gill and eviscerated carcass was dose-dependent, and remained elevated 4 days after the silver was removed. Microarray analysis also revealed a dose-dependent response pattern, with the largest number of genes affected in the 50 μg/L AgNP exposure. Pathway analysis of affected genes identified a number of GO terms that were significantly over-represented in the high AgNP dataset. These terms are associated with DNA damage repair, cellular restructuring, and developmental processes.

Research paper thumbnail of Photo-induced toxicity of Deepwater Horizon slick oil to blue crab ( Callinectes sapidus ) larvae

Environmental Toxicology and Chemistry, 2015

The 2010 Deepwater Horizon oil spill resulted in the accidental release of approximately 700 mill... more The 2010 Deepwater Horizon oil spill resulted in the accidental release of approximately 700 million L of crude oil into the Gulf of Mexico. Photo-induced toxicity after co-exposure to ultraviolet (UV) radiation is 1 mechanism by which polycyclic aromatic hydrocarbons (PAHs) from oil spills may exert toxicity. Blue crab are an important commercial and ecological resource in the Gulf of Mexico, and their largely transparent larvae may make them sensitive to PAH photo-induced toxicity. The goal of the present study was to examine the sensitivity of early lifestage blue crab (Callinectes sapidus) zoea to slick oil collected during the Deepwater Horizon spill. Blue crab zoea were exposed to 1 of several dilutions of water accommodated fractions from 1 of 2 sources of oil and gradations of natural sunlight in a factorial design. Two 7-h solar exposures were carried out with a recovery period (dark) in between. Survival was found to be UV- and PAH-dependent. Toxicity was observed within the range of surface PAH concentrations reported in the Gulf of Mexico during the Deepwater Horizon spill. These findings indicate that early lifestage blue crab are sensitive to photo-induced toxicity from Deepwater Horizon slick oil. Environ Toxicol Chem 2015;9999:1-6. © 2015 SETAC.