title: Seasonal variation in the skin transcriptome of common bottlenose dolphins (Tursiops truncatus) from the northern Gulf of Mexico.
abstract: As long-lived predators that integrate exposures across multiple trophic levels, cetaceans are recognized as sentinels for the health of marine ecosystems. Their utility as sentinels requires the establishment of baseline health parameters. Because cetaceans are protected, measurements obtained with minimal disruption to free ranging animals are highly desirable. In this study we investigated the utility of skin gene expression profiling to monitor health and contaminant exposure in common bottlenose dolphins (Tursiops truncatus). Remote integument biopsies were collected in the northern Gulf of Mexico prior to the Deepwater Horizon oil spill (May 2010) and during summer and winter for two years following oil contamination (2010-2011). A bottlenose dolphin microarray was used to characterize the skin transcriptomes of 94 individuals from three populations: Barataria Bay, Louisiana, Chandeleur Sound, Louisiana, and Mississippi Sound, Mississippi/Alabama. Skin transcriptomes did not differ significantly between populations. In contrast, season had a profound effect on gene expression, with nearly one-third of all genes on the array differing in expression between winter and the warmer seasons (moderated T-test; p<0.01, fold-change≥1.5). Persistent organic pollutants (POPs) in blubber changed concurrently, reaching >two-fold higher concentrations in summer compared to winter, due to a seasonal decrease in blubber thickness and loss of stored lipid. However, global gene expression did not correlate strongly with seasonally changing contaminant concentrations, most likely because the refractory, lipid-stored metabolites are not substrates for phase I or II xenobiotic detoxification pathways. Rather, processes related to cell proliferation, motility, and differentiation dominated the differences in expression in winter and the warmer seasons. More subtle differences were seen between spring and summer (1.5% of genes differentially expressed). However, two presumed oil-exposed animals from spring presented gene expression profiles more similar to the summer animals (presumed exposed) than to other spring animals. Seasonal effects have not previously been considered in studies assessing gene expression in cetaceans, but clearly must be taken into account when applying transcriptomic analyses to investigate their contaminant exposure or health status.
authors.affiliation: National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Charleston, South Carolina, United States of America.
authors.forename: Frances M
authors.initials: FM
authors.lastname: Van Dolah
authors.affiliation: National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Charleston, South Carolina, United States of America.
authors.forename: Marion G
authors.initials: MG
authors.lastname: Neely
authors.affiliation: National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Charleston, South Carolina, United States of America.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: McGeorge
authors.affiliation: National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Charleston, South Carolina, United States of America.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Balmer
authors.affiliation: Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Ylitalo
authors.affiliation: National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Charleston, South Carolina, United States of America.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Zolman
authors.affiliation: National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Charleston, South Carolina, United States of America.
authors.forename: Todd
authors.initials: T
authors.lastname: Speakman
authors.affiliation: Southeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Pascagoula, Mississippi, United States of America.
authors.forename: Carrie
authors.initials: C
authors.lastname: Sinclair
authors.affiliation: Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, California, United States of America.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Kellar
authors.affiliation: Southeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Lafayette, Louisiana, United States of America.
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Rosel
authors.affiliation: Southeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Pascagoula, Mississippi, United States of America.
authors.forename: Keith D
authors.initials: KD
authors.lastname: Mullin
authors.affiliation: National Centers for Coastal Ocean Science, National Ocean Service, National Oceanic and Atmospheric Administration, Charleston, South Carolina, United States of America.
authors.forename: Lori H
authors.initials: LH
authors.lastname: Schwacke
mesh_terms: D000407:Alabama; D000818:Animals; D001706:Biopsy; D050681:Bottle-Nosed Dolphin / Q000502:physiology*; D002980:Climate; D016000:Cluster Analysis; D017753:Ecosystem; D005260:Female; D005786:Gene Expression Regulation; D005843:Geography; D060851:Gulf of America; D008145:Louisiana; D008297:Male; D046228:Microarray Analysis; D008922:Mississippi; D009693:Nucleic Acid Hybridization; D059392:Petroleum Pollution / Q000032:analysis; D025341:Principal Component Analysis; D012621:Seasons; D012867:Skin / Q000378:metabolism*; D059467:Transcriptome; D014874:Water Pollutants, Chemical / Q000032:analysis; D015262:Xenobiotics
chemical_list: D014874:Water Pollutants, Chemical; D015262:Xenobiotics