Article

Biomarker responses in river otters experimentally exposed to oil contamination.

Institute of Arctic Biology, University of Alaska Fairbanks, 99775-7000, USA.
Journal of wildlife diseases (Impact Factor: 1.27). 08/2001; 37(3):489-508.
Source: PubMed

ABSTRACT Investigations in Prince William Sound (Alaska, USA) following the Exxon Valdez oil spill (EVOS) revealed that river otters (Lontra canadensis) on oiled shores had lower body mass and elevated values of biomarkers, than did otters living on nonoiled shores. In addition, otters from oiled areas selected different habitats, had larger home ranges, and less diverse diets than animals living in nonoiled areas. These differences between river otters from oiled shores and those from nonoiled areas strongly suggested that oil contamination had an effect on physiological and behavioral responses of otters. In this study, we explored the effects of crude oil contamination on river otters experimentally. We hypothesized that exposure to oil would result in elevated values of biomarkers, indicating induced physiological stress. Fifteen wild-caught male river otters were exposed to two levels of weathered crude oil (i.e., control, 5 ppm/day/kg body mass, and 50 ppm/day/kg body mass) under controlled conditions in captivity at the Alaska Sealife Center in Seward (Alaska, USA). Responses of captive river otters to oil ingestion provided mixed results in relation to our hypotheses. Although hemoglobin (Hb, and associated red blood cells) and white blood cells, and possibly interleukin-6 immunoreactive responded in the expected manner, other parameters did not. Aspartate aminotransferase, alanine aminotransferase, and haptoglobin (Hp), did not increase in response to oiling or decreased during rehabilitation. Conversely, principle-component analysis identified values of alkaline phosphatase as responding to oil ingestion in river otters. Our results suggested that opposing processes were concurring in the oiled otters. Elevated production of Hp in response to tissue damage by hydrocarbons likely occurred at the same time with increased removal of Hp-Hb complex from the serum, producing an undetermined pattern in the secretion of Hp. Thus, the use of individual biomarkers as indicators of exposure to pollutants may lead to erroneous conclusions because interactions in vivo can be complicated and act in opposite directions. Additionally, the biomarkers used in investigating effects of oiling on live animals usually are related to the heme molecule. Because of the opposing processes that may occur within an animal, data from a suite of heme-related biomarkers may produce results that are difficult to interpret. Therefore, we advocate the exploration and development of other biomarkers that will be independent from the heme cycle and provide additional information to the effect of oiling on live mammals.

0 0
 · 
0 Bookmarks
 · 
48 Views
  • [show abstract] [hide abstract]
    ABSTRACT: Haptoglobin (Hp) is one of the acute phase proteins (APP) in the blood of vertebrates that is involved in immune responses. Hp concentrations are found to vary under conditions of, for example, infection, trauma or cancer. These variations and the changes in its constitution are frequently used to assess the health status of mammals. In this work, Hp from the blood plasma of diseased and healthy harbor seals was isolated and structurally characterized. The process developed for the isolation of Hp is based on glycoprotein enrichment from crude plasma samples by means of ConA lectin affinity separation. Structural features of the protein backbone and the N-glycans were determined using MALDI-TOF/TOF-MS. De novo sequencing of seal Hp revealed an alpha-chain composed of 84 amino acids and a beta-chain comprising 245 amino acids. Comparison with Hp of the phylogenically related dog and human Hp 1-1 reveals the conserved and variable regions. All cysteine residues responsible for disulfide bonds and one glycosylation site have identical positions in the primary structures. Altogether, four possible glycosylation sites were identified. The glycoprofile is dominated by disialylated biantennary complex-type glycans.
    Journal of Proteome Research 05/2009; 8(6):2923-32. · 5.06 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Haptoglobin (Hp) which is synthesized in response to infection, inflammation, trauma or toxicological damage is known as a major acute phase protein in numerous species. Quantification of the circulating concentration of this protein can provide an objective measure of the health status, but there is a lack of investigations on harbour seals. We investigated the Hp concentration in samples of 123 seals (Phoca vitulina) from the German and Danish Wadden Sea to study physiological ranges of Hp levels. Hp levels between 2002, the end of the phocine distemper virus epidemic (PDV), and 2007 were considered, and Hp concentrations between animals of different sex, ages as well as living areas were compared. Furthermore, as a case study, six animals from the open sea isle Helgoland were investigated in 2006. Influences on the health status of the seal population e.g. the PDV epidemic were reflected by increased Hp levels in North Sea seals in 2002. The results of the Wadden Sea seals showed no significant age-, sex-, or geographical area-related differences. Interestingly, for the seals of the open sea isle Helgoland higher Hp values were measured compared to the Wadden Sea seals. The present study demonstrates that Hp can be used as a diagnostic tool to monitor the health status of harbour seals.
    Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology 10/2009; 155(1):67-71. · 1.61 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Many studies have evaluated why male mammals form social groups; few however have investigated how these groups are formed and maintained. We observed behavioral interactions of 15 male river otters (Lontra canadensis) captured in Prince William Sound (PWS), Alaska, and held in captivity for 10 mo. Because the otters were captured in various areas and differed in age and relatedness, we were able to test how kinship and age influenced social interactions. We also explored how kinship, age and social interactions in captivity related to geographic spacing after the otters were released back in PWS. In 284 h of observations, the otters exhibited more positive than negative interactions. Social network models indicated that in the early stage of captivity, there were more links among individuals than in the late stage. In the late-stage period, older animals that had higher testosterone levels exhibited increased social distance and lower information centrality (a network connectivity metric). Social distance was not related to genetic distance, nor did it relate directly to age, although both social distance and age were correlated with post-release geographic distance. Thus, the formation of male groups in coastal river otters is largely influenced by familiarity and past experience, rather than kinship. The maintenance of groups, especially during the mating season, is a function of reproductive status and age, with older animals withdrawing from the social network during that time. What other phenotypic characters may contribute to the formation and maintenance of river otter groups merit future exploration.
    Ethology 03/2009; 115(4):384 - 396. · 1.95 Impact Factor

Full-text (2 Sources)

View
19 Downloads
Available from
Mar 26, 2013