Pacific Ocean–wide profile of CYP1A1 expression, stable carbon and nitrogen isotope ratios, and organic contaminant burden in sperm whale skin biopsies

This paper is not subject to U.S. copyright. The definitive version was published in Environmental Health Perspectives 119 (2011): 337-343, doi:10.1289/ehp.0901809.Background: Ocean pollution affects marine organisms and ecosystems as well as humans. The International Oceanographic Commission recommends ocean health monitoring programs to investigate the presence of marine contaminants and the health of threatened species and the use of multiple and early-warning biomarker approaches. Objective: We explored the hypothesis that biomarker and contaminant analyses in skin biopsies of the threatened sperm whale (Physeter macrocephalus) could reveal geographical trends in exposure on an oceanwide scale. Methods: We analyzed cytochrome P450 1A1 (CYP1A1) expression (by immunohistochemistry), stable nitrogen and carbon isotope ratios (as general indicators of trophic position and latitude, respectively), and contaminant burdens in skin biopsies to explore regional trends in the Pacific Ocean. Results: Biomarker analyses revealed significant regional differences within the Pacific Ocean. CYP1A1 expression was highest in whales from the Galapagos, a United Nations Educational, Scientific, and Cultural Organization World Heritage marine reserve, and was lowest in the sampling sites farthest away from continents. We examined the possible influence of the whales’ sex, diet, or range and other parameters on regional variation in CYP1A1 expression, but data were inconclusive. In general, CYP1A1 expression was not significantly correlated with contaminant burdens in blubber. However, small sample sizes precluded detailed chemical analyses, and power to detect significant associations was limited. Conclusions: Our large-scale monitoring study was successful at identifying regional differences in CYP1A1 expression, providing a baseline for this known biomarker of exposure to aryl hydrocarbon receptor agonists. However, we could not identify factors that explained this variation. Future oceanwide CYP1A1 expression profiles in cetacean skin biopsies are warranted and could reveal whether globally distributed chemicals occur at biochemically relevant concentrations on a global basis, which may provide a measure of ocean integrity.Funding was provided by National Institute of Environmental Health Sciences grant P42-ES-0469, Superfund Basic Research Program grant P42ES007381, NOAA Sea Grant NA86RG0075 R/B-162, and the Ocean Alliance

Reprint of: CYP1A protein expression and catalytic activity in double-crested cormorants experimentally exposed to deepwater Horizon Mississippi Canyon 252 oil

Double-crested cormorants (Phalacrocorax auritus, DCCO) were orally exposed to Deepwater Horizon Mississippi Canyon 252 (DWH) oil to investigate oil-induced toxicological impacts. Livers were collected for multiple analyses including cytochrome P4501A (CYP1A) enzymatic activity and protein expression. CYP1A enzymatic activity was measured by alkoxyresorufin O-dealkylase (AROD) assays. Activities specific to the O-dealkylation of four resorufin ethers are reported: benzyloxyresorufin O-debenzylase (BROD), ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and pentoxyresorufin O-depentylase (PROD). CYP1A protein expression was measured by western blot analysis with a CYP1A1 mouse monoclonal antibody. In study 1, hepatic BROD, EROD, and PROD activities were significantly induced in DCCO orally exposed to 20 ml/ kg body weight (bw) oil as a single dose or daily for 5 days. Western blot analysis revealed hepatic CYP1A protein induction in both treatment groups. In study 2 (5 ml/kg bw oil or 10 ml/kg bw oil, 21 day exposure), all four hepatic ARODs were significantly induced. Western blots showed an increase in hepatic CYP1A expression in both treatment groups with a significant induction in birds exposed to 10 ml/kg oil. Significant correlations were detected among all 4 AROD activities in both studies and between CYP1A protein expression and both MROD and PROD activities in study 2. EROD activity was highest for both treatment groups in both studies while BROD activity had the greatest fold-induction. While PROD activity values were consistently low, the fold induction was high, usually 2nd highest to BROD activity. The observed induced AROD profiles detected in the present studies suggest both CYP1A4/1A5 DCCO isoforms are being induced after MC252 oil ingestion. A review of the literature on avian CYP1A AROD activity levels and protein expression after exposure to CYP1A inducers highlights the need for species-specific studies to accurately evaluate avian exposure to oil

Data from: Characterization of the gray whale Eschrichtius robustus genome and a genotyping array based on single-nucleotide polymorphisms in candidate genes

Genetic and genomic approaches have much to offer in terms of ecology, evolution, and conservation. To better understand the biology of the gray whale Eschrichtius robustus (Lilljeborg, 1861), we sequenced the genome and produced an assembly that contains ∼95% of the genes known to be highly conserved among eukaryotes. From this assembly, we annotated 22,711 genes and identified 2,057,254 single-nucleotide polymorphisms (SNPs). Using this assembly, we generated a curated list of candidate genes potentially subject to strong natural selection, including genes associated with osmoregulation, oxygen binding and delivery, and other aspects of marine life. From these candidate genes, we queried 92 autosomal protein-coding markers with a panel of 96 SNPs that also included 2 sexing and 2 mitochondrial markers. Genotyping error rates, calculated across loci and across 69 intentional replicate samples, were low (0.021%), and observed heterozygosity was 0.33 averaged over all autosomal markers. This level of variability provides substantial discriminatory power across loci (mean probability of identity of 1.6 × 10−25 and mean probability of exclusion >0.999 with neither parent known), indicating that these markers provide a powerful means to assess parentage and relatedness in gray whales. We found 29 unique multilocus genotypes represented among our 36 biopsies (indicating that we inadvertently sampled 7 whales twice). In total, we compiled an individual data set of 28 western gray whales (WGSs) and 1 presumptive eastern gray whale (EGW). The lone EGW we sampled was no more or less related to the WGWs than expected by chance alone. The gray whale genomes reported here will enable comparative studies of natural selection in cetaceans, and the SNP markers should be highly informative for future studies of gray whale evolution, population structure, demography, and relatedness

Influence of Life-History Parameters on Persistent Organic Pollutant Concentrations in Blubber of Eastern North Pacific Gray Whales (Eschrichtius robustus).

Exposure to persistent organic pollutants (POPs) can significantly impact marine mammal health, reproduction, and fitness. This study addresses a significant 20-year gap in gray whale contaminant monitoring through analysis of POPs in 120 blubber biopsies. The scope of this substantial sample set is noteworthy in its range and diversity with collection between 2003 and 2017 along North Americas west coast and across diverse sex, age, and reproductive parameters, including paired mothers and calves. Mean blubber concentrations of polychlorinated biphenyls (∑PCBs), dichlorodiphenyltrichloroethanes (∑DDTs), and chlordanes (∑CHLs) generally decreased since previous reports (1968-1999). This is the first report of polybrominated diphenyl ethers (PBDEs) and select hexachlorocyclohexanes (HCHs) in this species. Statistical modeling of the 19 most frequently detected compounds in this dataset revealed sex-, age-, and reproductive status-related patterns, predominantly attributed to maternal offloading. Mean POP concentrations differed significantly by sex in adults (17 compounds, up to 3-fold higher in males) but not in immatures (all 19 compounds). Mean POP concentrations were significantly greater in adults versus immatures in both males (17 compounds, up to 12-fold) and females (13 compounds, up to 3-fold). POP concentrations were detected with compound-specific patterns in nursing calves, confirming maternal offloading for the first time in this species

Eschrichtius robustus genome annotation

Gray whale (Eschrichtius robustus) genome annotation in gff format. MAKER 2.28b was used to annotate the genome assembly. Scaffolds with a minimum size of 1000bp from the genome assembly were used to produce the final annotation. Assembly and annotation were conducted on individual ER-14-168

Eschrichtius robustus annotated transcripts

Gray whale (Eschrichtius robustus) annotated transcripts from MAKER 2.28b in fasta format. Assembly and annotation were conducted on individual ER-14-168