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Blubber

The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Peter D Nichols – 1st expert on this subject based on the ideXlab platform

  • vertical distribution of lipids fatty acids and organochlorine contaminants in the Blubber of southern hemisphere humpback whales megaptera novaeangliae
    Marine Environmental Research, 2014
    Co-Authors: Courtney Waugh, Peter D Nichols, Martin Schlabach, Michael J Noad, Susan Bengtson Nash

    Abstract:

    Persistent organic pollutants (POPs), such as toxic lipophilic organochlorine (OC) compounds, accumulate in the Blubber tissue of marine mammals. Toxicological sampling methods most frequently target only the superficial Blubber layer. Vertical distribution of these contaminants through the Blubber mantle may, however, not be homogenous and could reflect any dissemination of lipids and fatty acids (FAs). It is therefore critical to assess stratification patterns in a species of interest as a quality control measure for interpretation of toxicological data. Here, we analysed and compared the distribution of lipids, FAs, and OCs in the outermost and innermost Blubber layer of southern hemisphere humpback whales. FA stratification was evident for short-chain (≤18) monounsaturated fatty acids (SC-MUFA), which were concentrated in the outer layer, consistent with the thermoregulatory role of this Blubber layer. This stratification was, however, not reflected in OC distribution, which was similar in the inner and outer Blubber layers of male humpback whales. By comparison, a noticeable gradient in total Blubber lipid from the outer to the inner layer was observed in two lactating females, which coincided with higher lipid normalised contaminant levels in the inner layer. This study contains the most comprehensive assessment of humpback whale Blubber stratification to date, however, further investigation of biological and ecological influencing factors is required.

  • differential mobilization of Blubber fatty acids in lactating weddell seals evidence for selective use
    Physiological and Biochemical Zoology, 2008
    Co-Authors: Kathryn E Wheatley, Peter D Nichols, Mark A Hindell, Robert Harcourt, Corey J A Bradshaw

    Abstract:

    Abstract A major source of energy during lactation in mammals is provided through the mobilization of Blubber fatty acids (FAs). We investigated the extent to which FAs were mobilized to support both maternal metabolic requirements and milk production in the Weddell seal and how this was reflected in the FA composition of the pup’s Blubber at the end of lactation (EL). FA composition of postpartum female Blubber was similar in the 2 yr of study (2002 and 2003) but differed markedly by EL. Pup Blubber FAs (at EL) were also different between years and did not match that of the mother’s milk or Blubber. Milk FA composition changed during lactation, which may have been a reflection of an increase in pup energy demands at different stages of development. In addition, there was evidence of feeding by some females during lactation, with higher levels of some FAs in the milk than in the Blubber. Our results indicate that differential mobilization of FAs occurred in lactating Weddell seals and that this was relate…

  • variation in the fatty acid composition of Blubber in cape fur seals arctocephalus pusillus pusillus and the implications for dietary interpretation
    Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2005
    Co-Authors: John P Y Arnould, Peter D Nichols, Matthew M Nelson, W H Oosthuizen

    Abstract:

    Analysis of the fatty acid (FA) composition of Blubber is a valuable tool in interpreting the diet of marine mammals. This technique is based on the principle that particular FA present in prey can be incorporated largely untransformed into predator adipose tissue stores, thereby providing biochemical signatures with which to identify prey species. Several studies of phocid seals and cetaceans have documented vertical stratification in the FA composition of Blubber such that inferences about diet may vary greatly depending on the layer of the Blubber that is analysed. It is not known whether Blubber in otariid seals (fur seals and sea lions) also displays vertical stratification in FA composition. Furthermore, it is not known whether the FA composition of Blubber is uniform in these species. In the present study, the vertical and regional variation in FA composition of Blubber was investigated in seven adult female Cape fur seals (Arctocephalus pusillus pusillus). The proportion of monounsaturated fatty acids (MUFA) was greater in the outer (43.6±1.3%) than inner portion (40.9±1.2%; t20=5.59, P<0.001) whereas the proportions were greater in the inner than outer portions for saturated fatty acids (23.6±0.5% and 21.9±0.6%, respectively, t20 = 5.31, P<0.001) and polyunsaturated fatty acids (PUFA, 35.5±0.7% and 34.5±0.7%, respectively, t20 = 3.81, P < 0.001). There was an inverse relationship between MUFA and PUFA in the Blubber, independent of sampling location. In addition, with the exception of the inner portion from non-lactating females, Blubber from the mammary area had the highest proportions of 18:1ω9c and total MUFA, followed by Blubber from the rump and neck, suggesting that the deposition and mobilisation of Blubber lipids may not be uniform around the body in otariid seals. These results support the need for Blubber tissue to be sampled from the same site on animals, and to the full depth of the Blubber layer, to minimise variation in FA profiles that could occur if different sites and depths were sampled. Such standardisation of sampling will further aid in interpreting diet in otariid seals using the FA Signature Analysis approach.

Cathy Debier – 2nd expert on this subject based on the ideXlab platform

  • persistent organic pollutant burden experimental pop exposure and tissue properties affect metabolic profiles of Blubber from gray seal pups
    Environmental Science & Technology, 2018
    Co-Authors: Kelly J Robinson, Cathy Debier, Jean-pierre Thomé, Ailsa J Hall, Gauthier Eppe, Kimberley A Bennett

    Abstract:

    Persistent organic pollutants (POPs) are toxic, ubiquitous, resist breakdown, bioaccumulate in living tissue, and biomagnify in food webs. POPs can also alter energy balance in humans and wildlife. Marine mammals experience high POP concentrations, but consequences for their tissue metabolic characteristics are unknown. We used Blubber explants from wild, gray seal (Halichoerus grypus) pups to examine impacts of intrinsic tissue POP burden and acute experimental POP exposure on adipose metabolic characteristics. Glucose use, lactate production, and lipolytic rate differed between matched inner and outer Blubber explants from the same individuals and between feeding and natural fasting. Glucose use decreased with Blubber dioxin-like PCBs (DL-PCB) and increased with acute experimental POP exposure. Lactate production increased with DL-PCBs during feeding, but decreased with DL-PCBs during fasting. Lipolytic rate increased with Blubber dichlorodiphenyltrichloroethane and its metabolites (DDX) in fasting anim…

  • Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants
    Science of The Total Environment, 2015
    Co-Authors: Sarah H Peterson, Cathy Debier, Daniel E Crocker, Alin C Dirtu, Govindan Malarvannan, Adrian Covaci, Lisa K Schwarz, Michael G. Peterson, Daniel P Costa

    Abstract:

    As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in Blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N=24), we satellite tracked and sampled the same seals before and after their approximately sevenmonthlong foraging trip.Formales,we sampled different adults and sub-adults before (N=14) and after (N=15) the same foraging trip. For females,we calculated Blubber burdens for all compounds. The highest POP concentrations in males and females were found for ΣDDTs andΣPCBs. In Blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females,ΣDDT andΣPBDEs were highly correlated in Blubber and serum.While ΣPCBs were highly correlatedwithΣDDTs andΣPBDEs in Blubber and serum formales,ΣPCBs showed weaker correlationswith both compounds in females. As females gainedmasswhile foraging, concentrations of nearly all POPs in inner and outer Blubber significantly decreased; however, the absolute burden in Blubber significantly increased, indicating ingestion of contaminantswhile foraging. Additionally,we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences inΣDDTs,ΣPBDEs, MeO-BDE 47, as well as the ratio ofΣDDTs toΣPCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations ofΣDDTs and ΣPBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in 13C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in deep ocean food webs.

  • mobilisation of Blubber fatty acids of northern elephant seal pups mirounga angustirostris during the post weaning fast
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2015
    Co-Authors: Caroline Louis, Daniel E Crocker, Laurent Perdaens, Stephanie Suciu, Stephen K Tavoni, Cathy Debier

    Abstract:

    Northern elephant seal pups were longitudinally sampled at Ano Nuevo State Reserve during the post-weaning fast, in order to evaluate the changes of fatty acid (FA) profiles in serum as well as in the inner and outer layers of Blubber. The major FAs of inner and outer Blubber layers were broadly similar to those found in NES maternal milk previously measured, suggesting a direct deposit of dietary FAs in the Blubber during the suckling period. The outer Blubber layer contained more medium-chain monounsaturated FAs that contribute in keeping the fluidity of this tissue at cold temperatures. It was compensated by higher proportions of saturated FAs in the inner Blubber layer. The FA signature of inner Blubber, the layer that is mainly mobilised during energy deprivation, slightly differed from the signature of serum. There were greater proportions of medium-chain saturated FAs and ω-6 polyunsaturated FAs, and lower proportions of long-chain saturated FAs, medium-chain monounsaturated FAs and long-chain monounsaturated FAs in serum as compared to inner Blubber. We also demonstrated that lipophilicity is the main factor governing the mobilisation of FAs from Blubber. The least lipophilic FAs were preferentially hydrolysed from Blubber, leading to an enrichment of the more lipophilic FAs in this tissue with the progression of the fast. The expression levels of HSL and ATGL, which are two enzymes involved in the lipolytic process, remained stable during the post-weaning fast. This suggests that the pups have developed the enzymatic mechanisms for an efficient lipolysis as soon as the first week of fast.

Daniel E Crocker – 3rd expert on this subject based on the ideXlab platform

  • Blubber transcriptome response to acute stress axis activation involves transient changes in adipogenesis and lipolysis in a fasting adapted marine mammal
    Scientific Reports, 2017
    Co-Authors: Jane Khudyakov, Cory D Champagne, L M Meneghetti, Daniel E Crocker

    Abstract:

    Stress can compromise an animal’s ability to conserve metabolic stores and participate in energy-demanding activities that are critical for fitness. Understanding how wild animals, especially those already experiencing physiological extremes (e.g. fasting), regulate stress responses is critical for evaluating the impacts of anthropogenic disturbance on physiology and fitness, key challenges for conservation. However, studies of stress in wildlife are often limited to baseline endocrine measurements and few have investigated stress effects in fasting-adapted species. We examined downstream molecular consequences of hypothalamic-pituitary-adrenal (HPA) axis activation by exogenous adrenocorticotropic hormone (ACTH) in Blubber of northern elephant seals due to the ease of Blubber sampling and its key role in metabolic regulation in marine mammals. We report the first phocid Blubber transcriptome produced by RNAseq, containing over 140,000 annotated transcripts, including metabolic and adipocytokine genes of interest. The acute response of Blubber to stress axis activation, measured 2 hours after ACTH administration, involved highly specific, transient (lasting <24 hours) induction of gene networks that promote lipolysis and adipogenesis in mammalian adipocytes. Differentially expressed genes included key adipogenesis factors which can be used as Blubber-specific markers of acute stress in marine mammals of concern for which sampling of other tissues is not possible.

  • Blubber cortisol qualitatively reflects circulating cortisol concentrations in bottlenose dolphins
    Marine Mammal Science, 2017
    Co-Authors: Cory D Champagne, Daniel E Crocker, Nicholas M Kellar, Samuel K Wasser, Rebecca K Booth, Marisa L Trego, Dorian S Houser

    Abstract:

    Stress hormones, released into circulation as a consequence of disturbance, are classically assayed from blood samples but may also be detected in a variety of matrices. Blubber and fecal samples can be remotely collected from free-ranging cetaceans without the confounding hormone elevations associated with chase, capture, and handling required to collect blood samples. The relationship between cortisol concentrations in circulation with that of Blubber and feces, however, is unknown. To assess these associations, we elevated cortisol by orally administering hydrocortisone for five days in five bottlenose dolphins. Voluntary blood and fecal samples were collected daily; Blubber biopsies were collected on day one, just prior to hydrocortisone administration, and days three and five of hydrocortisone administration. We evaluated subsequent changes in several circulating stress hormones as well as cortisol and glucocorticoid metabolites in Blubber and feces, respectively. There was a significant association between cortisol levels in serum and in Blubber (F1,12.7 = 14.3, P < 0.01, mR2 = 0.57) despite substantial variability in Blubber cortisol levels. Counterintuitively, fecal cortisol metabolite levels were inversely related to serum cortisol. The relationship between serum and Blubber cortisol levels suggests Blubber samples from remote sampling may be useful to detect stress loads in this species.

  • Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants
    Science of The Total Environment, 2015
    Co-Authors: Sarah H Peterson, Cathy Debier, Daniel E Crocker, Alin C Dirtu, Govindan Malarvannan, Adrian Covaci, Lisa K Schwarz, Michael G. Peterson, Daniel P Costa

    Abstract:

    As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in Blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N=24), we satellite tracked and sampled the same seals before and after their approximately sevenmonthlong foraging trip.Formales,we sampled different adults and sub-adults before (N=14) and after (N=15) the same foraging trip. For females,we calculated Blubber burdens for all compounds. The highest POP concentrations in males and females were found for ΣDDTs andΣPCBs. In Blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females,ΣDDT andΣPBDEs were highly correlated in Blubber and serum.While ΣPCBs were highly correlatedwithΣDDTs andΣPBDEs in Blubber and serum formales,ΣPCBs showed weaker correlationswith both compounds in females. As females gainedmasswhile foraging, concentrations of nearly all POPs in inner and outer Blubber significantly decreased; however, the absolute burden in Blubber significantly increased, indicating ingestion of contaminantswhile foraging. Additionally,we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences inΣDDTs,ΣPBDEs, MeO-BDE 47, as well as the ratio ofΣDDTs toΣPCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations ofΣDDTs and ΣPBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in 13C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in deep ocean food webs.