Effects of petroleum on mink applied as a model for reproductive success in sea otters.

Ranch-reared mink (Mustela vison) were used as a model in an experimental trial to investigate the potential effects of exposure to two petroleum products on sea otters (Enhydra lutris). Mink were exposed either dermally on one occasion 60 days prior to breeding or via low level contamination of their diets daily from 60 days prior to breeding (January 1994) until weaning of kits (June 1994). For dermal exposure, we placed mink in either a slick of Alaskan North Slope crude oil (n = 24) or bunker C fuel oil (n = 24) on sea water or sea water alone (n = 10) for 1 min. For dietary exposure, we fed mink rations containing 500 ppm of either Alaskan North Slope crude oil (n = 24) or bunker C fuel oil (n = 24; control, n = 15). The number of liveborn kits did not differ significantly among mink exposed dermally (5.0 kits/female for crude oil and 6.5 kits/female for bunker C fuel oil) and unexposed controls (5.3 kits/female). However, only 2.3 and 0.7 kits were produced per female for those exposed through the diet to crude oil and bunker C fuel oil, respectively. Females with reduced reproductive success had no clinical signs of toxicosis or behavioral abnormalities. In addition, kits of females exposed through the diet had poor survival to weaning. Once mature, kits born to females exposed to bunker C fuel oil in the diet had significantly reduced reproductive success (3.4 kits/female) although their only exposure to the petroleum products was in utero or during nursing. Therefore, it is possible that sea otter populations consuming contaminated food sources or colonizing previously oiled habitats will have reduced reproductive success.     

The Smell of New Competitors: The Response of American Mink, Mustela vison, to the Odours of Otter, Lutra lutra and Polecat, M. putorius

We tested the response of wild American mink (an established alien species in the UK), to the odours of unfamiliar mink, European polecat and Eurasian otter. Polecats are similar in size and habits to mink, otters are larger than mink and a dominant competitor; both are native to the UK and both were absent during the original colonization by mink but are now undergoing natural population recoveries. The response of mink to experimental odours was assessed by counting the numbers of tracks (footprints) on rafts treated with anal gland secretions, and compared with response to a control raft, on two rivers in the Upper Thames valley, UK. Remote video showed that the number of tracks was positively correlated with the time that mink spent investigating an odour. We found that mink were attracted to the odours of both unfamiliar mink and polecats. There was little evidence that mink avoided the odour of otters. We suggest that, during an encounter with a polecat, mink may behave much as they would to a conspecific. We infer from the response of mink to the odour of otters, that, if mink do avoid otters, the mechanism of avoidance is likely to be complex, situation-dependent and perhaps affected by prior experience.     

Understanding the inter-specific dynamics of two co-existing predators in the Tierra del Fuego Archipelago: the native southern river otter and the exotic American mink

Knowledge about interactions between endangered native southern river otters (Lontra provocax) and introduced American mink (Neovison vison) is essential for effective management of both species. We evaluated competition for spatial and trophic niches between otter and mink in overlapping and non-overlapping areas, comparing distribution, habitat preference, diet and mink marking behavior. We surveyed otter and mink signs along 250 km of Beagle Channel coastline. Habitat suitability models were constructed based on species presence/absence and habitat characteristics, using generalized linear models. Feces were collected for diet analyses. Otters used forested coasts with 12°–32° shoreline slope and without human influence, and our evidence suggests they were not affected by mink presence. Mink preferred forested and shrubland coasts with 10°–28° shoreline slope. Neither human influence nor otter presence affected mink habitat occupation, but in the presence of otters, mink left fewer signs. Otters consumed more aquatic prey than mink, and mink modified their diet in the presence of otters, consuming more exotic small terrestrial mammals and less fish as well as shifting to smaller and shallower fish species that are less consumed by otters. Mink showed more plastic, generalist behavior than otters, being more tolerant of human presence, using more habitat types and having greater diet breadth. At the same time, otters apparently affect mink adversely and could help limit their invasion in sympatric areas. Conservation and recovery of otters, therefore, may produce a secondary benefit of simultaneously reducing the effect of mink, thereby providing an additional way to control this exotic predator’s population.     

Evidence of secondary poisoning of free-ranging riparian mustelids by anticoagulant rodenticides in France: implications for conservation of European mink (Mustela lutreola)

Because of the rapid decline of the endangered European mink (Mustela lutreola) populations in France, a national conservation program has been put into action, including research to understand the causes of decline. As part of this research, concentrations of eight anticoagulant rodenticides were examined in livers from 122 carcasses of four species of free-ranging mustelids collected between 1990 and 2002 in southwestern France. Bromadiolone residue was found in all species and 9% of the sample (one of 31 European mink, three of 47 American mink [Mustela vison], five of 33 polecats [Mustela putorius], and two of 11 European otters [Lutra lutra]). Liver concentrations ranged from 0.6 mug/g to 9.0 mug/g. Chlorophacinone residue was found in two species and 4% of the sample (in four of the American mink and in one of the otters), with liver concentrations ranging from 3.4 mug/g to 8.5 mug/g. Two polecats and one American mink had lesions and liver residues indicating bromadiolone was directly responsible for their death. However, most of our study animals survived secondary poisoning until they were caught; this study certainly underestimates the extent of fatal exposure of mustelids to rodenticides. Moreover, anticoagulant poisoning could increase their vulnerability to other causes of death. The current status of the endangered European mink population is such that any additional risk factor for mortality is important, and it is thus urgent to monitor and reduce the extensive use of bromadiolone and chlorophacinone against field rodents in France.     

Assessing Risks to Sea Otters and the Exxon Valdez Oil Spill: New Scenarios,Attributable Risk,and Recovery

The Exxon Valdez oil spill occurred more than two decades ago, and the Prince William Sound ecosystem has essentially recovered. Nevertheless, discussion continues on whether or not localized effects persist on sea otters (Enhydra lutris) at northern Knight Island (NKI) and, if so, what are the associated attributable risks. A recent study estimated new rates of sea otter encounters with subsurface oil residues (SSOR) from the oil spill. We previously demonstrated that a potential pathway existed for exposures to polycyclic aromatic hydrocarbons (PAHs) and conducted a quantitative ecological risk assessment using an individual-based model that simulated this and other plausible exposure pathways. Here we quantitatively update the potential for this exposure pathway to constitute an ongoing risk to sea otters using the new estimates of SSOR encounters. Our conservative model predicted that the assimilated doses of PAHs to the 1-in-1000th most-exposed sea otters would remain 1–2 orders of magnitude below the chronic effects thresholds. We re-examine the baseline estimates, post-spill surveys, recovery status, and attributable risks for this subpopulation. We conclude that the new estimated frequencies of encountering SSOR do not constitute a plausible risk for sea otters at NKI and these sea otters have fully recovered from the oil spill.     

Differential gene expression induction by TRAIL in B chronic lymphocytic leukemia (B-CLL) cells showing high versus low levels of Zap-70

Among 14 peripheral blood samples obtained from patients affected by B chronic lymphocytic leukemia (B-CLL) at initial stages (Rai 0-1) of the disease, 6 showed intermediate/high levels of Zap-70 while 8 displayed low/absent levels of Zap-70. Although Zap-70(high) and Zap-70(low) B-CLL samples displayed similar levels of surface death receptor TRAIL-R2, recombinant TRAIL induced cytotoxicity only in a subset of Zap-70(low) B-CLL samples while Zap-70(high) were completely resistant to TRAIL. The gene expression profiling was next analyzed in all B-CLL samples treated with either chlorambucil or recombinant TRAIL. While chlorambucil up-regulated the steady-state mRNA levels of known p53 target genes, such as PUMA, Fas/CD95 and MDM2 in all B-CLL samples examined, it significantly down-regulated survivin in Zap-70(low) but not in Zap-70(high). On the other hand, recombinant TRAIL up-regulated the expression of several cytokines (IL-1beta, IL-1alpha, IL-8), which have been involved in promoting B-CLL cell survival. In particular, TRAIL selectively up-regulated IL-1beta in Zap-70(low) B-CLL samples, while it markedly and selectively up-regulated its own mRNA and that of cyclooxigenase-2 (COX-2) in Zap-70(high). Taken together, our findings suggest that a significant expression of Zap-70 modulate the response of B-CLL to TRAIL, which might represents an initial step in the pathogenesis of B-CLL.     

Differential habitat use promotes sustainable coexistence between the specialist otter and the generalist mink

Optimal foraging and habitat selection theories predict that heterogeneous environments should favour the coexistence of competitors, especially when the dominant competitor is a specialist and the sub-ordinate is a generalist. In this paper, we analysed differential habitat use as a potential mechanism for the coexistence of two competing riparian mammals, the specialist and dominant Eurasian otter ( Lutra lutra ) and the generalist and sub-ordinate American mink ( Mustela vison ). We tested three hypotheses: H1: mink coexist with otters for longer in areas with abundance of habitats hosting terrestrial prey because, by not relying on aquatic prey, mink can segregate from its competitor. H2: the characteristics of the habitat closer to the riverbank will affect the length of time the two species coexist, because mink are still tied to the water even in the presence of otters. H3: denser vegetative cover along the bank increases the duration of coexistence of mink and otters because it reduces the frequency of their encounters. The first hypothesis was supported by the data and we found that in areas where terrestrial prey was abundant mink coexisted for longer with otters. The second hypothesis was also supported by the data and the characteristics of the habitat closer to the riverbank were the most important in determining coexistence time. Finally, we did not find supporting evidence for the third hypothesis. This study provides strong evidence that habitat heterogeneity plays an important role in determining the likelihood of coexistence of American mink with Eurasian otters. This result is particularly important from a conservation standpoint. Mink are invasive and a threat to endangered species in parts of their range. The knowledge that mink have a higher chance to persist in the presence of otters when terrestrial prey is abundant should be used to target areas for preferential mink management.     

Feeding habits of the otter and the American mink in Bialowieza Primeval Forest (Poland) compared to other Eurasian populations

Diets of the otter Lutra lutra and the American mink Mustela vison were studied by scat analysis on five woodland rivers and streams in eastern Poland. Fish constituted 51% of food biomass consumed by otters in spring‐summer and 40% in autumn‐winter, with common fish (perch Perca fluviatilis, pike Esox lucius, and roach Rutilus rutilus) being captured most frequently by the otters. Amphibians (mainly Rana temporaria, which also dominated in the living community) made up 34% of otters’ food biomass in spring‐summer and 58% in autumn‐winter. American mink relied on three prey groups: fish (40% in spring‐summer, and 10% in autumn‐winter), frogs (32% and 51%, respectively), and small mammals (21% and 36%). Out of available Micromammalia, mink strongly selected the root vole Microtus oeconomus. The cold season diet of both otter and mink depended on river size. On small rivers with forested valleys, otters and mink fed nearly exclusively on amphibians (72–90% of food biomass). With size of a river increasing and riverside habitat becoming more open (sedge and reed marshes instead of forests), otters shifted to catching predominantly fish (up to 76% in diet) and mink to preying on small mammals (up to 65% in diet).
Review of literature on otter and mink in Eurasia showed that their diets did not change with latitude (as indicators of climate severity and duration of water freezing) but they depended on habitats. In otter diet, the mean share of fish declined from 94% (SE 1.7) on sea shores, to 71% (SE 2.9) on lakes and fish ponds, to 64% (SE 2.8) on rivers and streams. The roles of amphibians and crustaceans increased in the same gradient (from 0 to 15%, and from 3 to 7%, respectively). On inland waters, the abundance of crayfish was the essential factor differentiating otters’ diet composition. In Eurasia, the staple food types of American mink on rivers and streams were fish (on average, 27% in diet, SE 3.9), mammals (30%, SE 5.0), and amphibians (17%, SE 4.8), whereas on lakes and ponds mink fed predominantly on birds (on average, 33% in diet, SE 10.1) and fish (28%, SE 9.5). In the Palaearctic region, over a wide gradient of habitats, otters appeared strongly specialised on prey taken from water, whereas American mink was a typical generalist capable of utilising several prey groups originating from both water and land.     

IL-4 up-regulates epidermal chemotactic,angiogenic, and pro-inflammatory genes and down-regulates antimicrobial genes in vivo and in vitro: Relevant in the pathogenesis of atopic dermatitis

Atopic dermatitis (AD) is a common chronic inflammatory skin disease. Although the pathogenesis of AD is not fully understood, we and others have shown that IL-4 plays a key role. In this study we aimed to identify keratinocyte genes regulated by IL-4 that may play important roles in the pathophysiology of AD. HaCat cells were treated with IL-4 at various concentrations for 24 h, and PCR gene array on inflammation/autoimmunity was performed three times for analysis of differential gene expression. Of all the 370 genes examined, 32 and 53 genes are up- and down-regulated, respectively. Specifically related to AD, chemokines CCL3L1, CCL8, CCL24, CCL25, CCL26, CXCL6 and CXCL16 are up-regulated by IL-4. Pro-inflammatory factors, such as IL-19, IL-20, IL-1α, IL-12Rβ2, IL-25, IL-31RA, OSMR and nitric oxide synthase 2, are also up-regulated. In addition, IL-4 up-regulates VEGFA, a pro-angiogenic factor. In contrast, antimicrobial peptides (AMPs) or factors involved in APM production, such as IFN-κ, S100s, Toll-like receptors, and several chemokines are down-regulated. Similarly IL-4 also down-regulates TNF-α, lymphotoxin-β, an IgE suppressor, TNFSF18, a T-cells function regulator, and the glucocorticoid receptor. On the in vivo level, real-time RT-PCR on the selected genes confirmed that IL-4 up-regulates chemokines, proinflammatory cytokines while it suppresses AMP production related genes in the skin obtained from IL-4 Tg mice. Detailed examination of these genes will delineate their specific roles in chemotaxis, inflammation, angiogenesis and AMP production, all of which may contribute to the development and progression of AD.     

MORTALITY OF SEA OTTERS IN PRINCE WILLIAM SOUND FOLLOWING THE EXXON VALDEZ OIL SPILL

Abstract: This paper presents an estimate of the total number of sea otters that died as a direct consequence of the oil spill that occurred when the T/V Exxon Valdez grounded in Prince William Sound, Alaska on 24 March 1989. We compared sea otter counts conducted from small boats throughout the Sound during the summers of 1984 and 1985 to counts made after the spill during the summer of 1989. We used ratio estimators, corrected for sighting probability, to calculate otter densities and population estimates for portions of the Sound affected by the oil spill. We estimated the otter population in the portion of Prince William Sound affected by the oil was 6,546 at the time of the spill and that the post-spill population in the summer of 1989 was 3,898, yielding a loss estimate of approximately 2,650. Bootstrapping techniques were used to approximate confidence limits on the loss estimate of about 500–5,000 otters. The wide confidence limits are a result of the complex scheme required to estimate losses and limitations of the data. Despite the uncertainty of the loss estimate it is clear that a significant fraction of the otters in the spill zone survived. We observed otters persisting in relatively clean embayments throughout the oil spill zone suggesting that the highly convoluted coastline of Prince William Sound produced refuges that allowed some sea otters in the oil spill area to survive.     

Mustelid herpesvirus-2, a novel herpes infection in northern sea otters (Enhydra lutris kenyoni)

Oral ulcerations and plaques with epithelial eosinophilic intranuclear inclusions were observed in northern sea otters (Enhydra lutris kenyoni) that died or were admitted for rehabilitation after the 1989 Exxon Valdez oil spill (EVOS) in Alaska, USA. Transmission electron microscopy demonstrated the presence of herpesviral virions. Additionally, a serologic study from 2004 to 2005 found a high prevalence of exposure to a herpesvirus in live-captured otters. Tissues from 29 otters after the EVOS and nasal swabs from 83 live-captured otters in the Kodiak Archipelago were tested for herpesviral DNA. Analysis identified a novel herpesvirus in the gamma subfamily, most closely related to Mustelid herpesvirus-1 from badgers. Results indicated that this herpesvirus is associated with ulcerative lesions but is also commonly found in secretions of healthy northern sea otters.     

Biomarker responses in river otters experimentally exposed to oil contamination

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.     

Influence of some environmental variables on the ascorbic acid status of striped mullet, Mugil cephalus Linn., tissues. III. Effects of exposure to oil

Exposure to water-soluble fractions (WSF) of a crude and two fuel oils altered the ascorbic acid (AsA) content of several striped mullet, Mugil cephalus , tissues. Exposure to sublethal concentrations of all three WSFs caused a depletion of AsA reserves in brain, gill, kidney and liver tissues, but not in muscle. There was a marked decline in AsA stores in kidney and gill tissues after only one day of exposure to WSFs of both crude and fuel oils. Liver AsA concentrations were significantly depleted after one week of oil exposure. Brain AsA content was only significantly depleted during chronic exposure to the highest oil concentration (20% WSF). A dose-dependent depletion of AsA reserves in the liver but not in the other tissues was observed one week after a single exposure to 2–20% WSFs of a No. 2 fuel oil. Exposure to 20% WSF of the No. 2 fuel oil caused a 47% decrease in liver AsA content one week later. Hepatic concentrations were still significantly depleted after 15 days, but had returned to control levels 20 days after the initial exposure. The data suggest that the depletion of tissue AsA reserves in fish inhabiting oil-contaminated environments could be sufficient on occasions to lead to AsA deficiency.     

A Quantitative Ecological Risk Assessment of the Toxicological Risks from Exxon Valdez Subsurface Oil Residues to Sea Otters at Northern Knight Island,Prince William Sound,Alaska

A comprehensive, quantitative risk assessment is presented of the toxicological risks from buried Exxon Valdez subsurface oil residues (SSOR) to a subpopulation of sea otters (Enhydra lutris) at Northern Knight Island (NKI) in Prince William Sound, Alaska, as it has been asserted that this subpopulation of sea otters may be experiencing adverse effects from the SSOR. The central questions in this study are: could the risk to NKI sea otters from exposure to polycyclic aromatic hydrocarbons (PAHs) in SSOR, as characterized in 2001–2003, result in individual health effects, and, if so, could that exposure cause subpopulation-level effects? We follow the U.S. Environmental Protection Agency (USEPA) risk paradigm by: (a) identifying potential routes of exposure to PAHs from SSOR; (b) developing a quantitative simulation model of exposures using the best available scientific information; (c) developing scenarios based on calculated probabilities of sea otter exposures to SSOR; (d) simulating exposures for 500,000 modeled sea otters and extracting the 99.9% quantile most highly exposed individuals; and (e) comparing projected exposures to chronic toxicity reference values. Results indicate that, even under conservative assumptions in the model, maximum-exposed sea otters would not receive a dose of PAHs sufficient to cause any health effects; consequently, no plausible toxicological risk exists from SSOR to the sea otter subpopulation at NKI.     

Transcriptomic Analyses of the Biological Effects of Airborne PM2.5 Exposure on Human Bronchial Epithelial Cells

Epidemiological studies have associated high levels of airborne particulate matter (PM) with increased respiratory diseases. In order to investigate the mechanisms of air pollution-induced lung toxicity in humans, human bronchial epithelial cells (16HBE) were exposed to various concentrations of particles smaller than 2.5 μm (PM2.5) collected from Beijing, China. After observing that PM2.5 decreased cell viability in a dose-dependent manner, we first used Illumina RNA-seq to identify genes and pathways that may contribute to PM2.5-induced toxicity to 16HBE cells. A total of 539 genes, 283 up-regulated and 256 down-regulated, were identified to be significantly differentially expressed after exposure to 25 μg/cm² PM2.5. PM2.5 induced a large number of genes involved in responses to xenobtiotic stimuli, metabolic response, and inflammatory and immune response pathways such as MAPK signaling and cytokine-cytokine receptor interaction, which might contribute to PM2.5-related pulmonary diseases. We then confirmed our RNA-seq results by qPCR and by analysis of IL-6, CYP1A1, and IL-8 protein expression. Finally, ELISA assay demonstrated a significant association between exposure to PM2.5 and secretion of IL-6. This research provides a new insight into the mechanisms underlying PM2.5-induced respiratory diseases in Beijing.