Showing papers on "Mink published in 2010"

Detection of a novel astrovirus in brain tissue of mink suffering from shaking mink syndrome by use of viral metagenomics.

Abstract: In 2000, farmed mink kits in Denmark were affected by a neurological disorder. The characteristic clinical signs included shaking, staggering gait, and ataxia. The disease, given the name shaking mink syndrome, was reproduced by the inoculation of brain homogenate from affected mink kits into healthy ones. However, the etiology remained unknown despite intensive efforts. In this study, random amplification and large-scale sequencing were used, and an astrovirus was detected in the brain tissue of three experimentally infected mink kits. This virus also was found in the brain of three mink kits naturally displaying the disease but not in the six healthy animals investigated. The complete coding region of the detected astrovirus was sequenced and compared to those of both a mink astrovirus associated with preweaning diarrhea and to a recently discovered human astrovirus associated with a case of encephalitis in a boy with x-linked agammaglobulinemia. The identities were 80.4 and 52.3%, respectively, showing that the virus described in this study was more similar to the preweaning diarrhea mink astrovirus. For the nonstructural coding regions the sequence identity was around 90% compared to that of the astrovirus, which is associated with preweaning diarrhea in mink. The region coding for the structural protein was more diverse, showing only 67% sequence identity. This finding is of interest not only because the detected virus may be the etiological agent of the shaking mink syndrome but also because this is one of the first descriptions of an astrovirus found in the central nervous system of animals.

The accuracy of scat identification in distribution surveys: American mink, Neovison vison, in the northern highlands of Scotland

Abstract: Distribution data for elusive species are often based on detection of field signs rather than of the animal itself. However, identifying field signs can be problematic. We present here the results of a survey for American mink, Neovison vison, in the northern highlands of Scotland to demonstrate the importance of verifying field sign identification. Three experienced surveyors located scats, which they identified as mink scats, at seven of 147 sites surveyed and “possible” mink scats at a further 50 sites. Mitochondrial DNA was successfully extracted from 45 of 75 (60%) scats, collected from 31 of the 57 “positive” sites; sequencing of amplified DNA fragments showed that none of these scats was actually of mink origin. We consider the implications of erroneous survey data and the potential waste of resources and misdirection of conservation/management actions. We discuss potential methods that may be useful to verify field sign identification, including the use of DNA analysis, and stress that verification is crucial to ensure rigorous and reliable survey data.

MINK and TNIK differentially act on Rap2-mediated signal transduction to regulate neuronal structure and AMPA receptor function.

Abstract: Misshapen/NIKs (Nck-interacting kinases)-related kinase (MINK) and closely related TRAF2/Nck-interacting kinase (TNIK) are proteins that specifically bind to activated Rap2 and are thus hypothesized to relay its downstream signal transduction. Activated Rap2 has been found to stimulate dendritic pruning, reduce synaptic density and cause removal of synaptic AMPA receptors (AMPA-Rs) (Zhu et al., 2005; Fu et al., 2007). Here we report that MINK and TNIK are postsynaptically enriched proteins whose clustering within dendrites is bidirectionally regulated by the activation state of Rap2. Expression of MINK and TNIK in neurons is required for normal dendritic arborization and surface expression of AMPA receptors. Overexpression of a truncated MINK mutant unable to interact with Rap2 leads to reduced dendritic branching and this MINK-mediated effect on neuronal morphology is dependent upon Rap2 activation. While similarly truncated TNIK also reduces neuronal complexity, its effect does not require Rap2 activity. Furthermore, Rap2-mediated removal of surface AMPA-Rs from spines is entirely abrogated by coexpression of MINK, but not TNIK. Thus, although both MINK and TNIK bind GTP-bound Rap2, these kinases employ distinct mechanisms to modulate Rap2-mediated signaling. MINK appears to antagonize Rap2 signal transduction by binding to activated Rap2. We suggest that MINK interaction with Rap2 plays a critical role in maintaining the morphological integrity of dendrites and synaptic transmission.

Long-term data on invaders: when the fox is away, the mink will play

Abstract: Studies of the effects and population dynamics of invasive species typically cover only short time periods. However, populations of invasive species interact with native species, and these interactions may have strong effects on invaders’ populations and effects over time. We present and analyze long-term data on invasive American mink (Neovison vison), native red fox (Vulpes vulpes), and mountain hare (Lepus timidus) in Sweden. The mink’s population dynamics followed a pattern of logistic growth from the late 1930s to the late 1970s. In the early 1980s, however, the population tripled, then declined sharply. We suggest that the mink’s population tripling was caused by a drastic decline in red fox populations, which caused terrestrial prey to increase. Later recovery of the fox population reversed the trend and caused the mink population’s recent decline. Our study shows that species interactions between native and invasive species, and therefore biotic resistance, can change dramatically over time.

Food niche variation of European and American mink during the American mink invasion in north-eastern Belarus

Abstract: Understanding processes allowing the co-existence of ecologically similar species is important but difficult to study in community ecology. Introductions of alien species are unplanned experiments allowing investigation of co-adaptation of both native and invasive species over a short period. We analysed food niche differentiation between native European mink and alien American mink after invasion of the latter species in Belarus. European mink feed mainly on crayfish, frogs and fish whereas American mink prefer small mammals, fish and frogs. The diet of both species varied between seasons and during the period of alien mink invasion. Concurrent with the progress of American mink invasion, the European mink food niche has narrowed to feeding mainly on frogs, with the proportion of aquatic prey (fish and crayfish) in their diet drastically reduced. In contrast, the American mink food niche became wider during invasion. The breadth was stable but included a varied proportion of different prey categories: namely an increased proportion of aquatic prey and a decreased proportion of water vole and waterfowl. The increase in abundance of American mink saw a decrease in the proportion of larger prey in their diet. When American mink preyed more often on frogs, food niche overlap of both predators increased. This result suggests that arrival of an alien competitor reduced food abundance (exploitative competition) and caused a change in native mink diet.

In vitro and whole animal evidence that methylmercury disrupts GABAergic systems in discrete brain regions in captive mink

Abstract: The effects of mercury (Hg) on key components of the GABAergic system were evaluated in discrete brain regions of captive juvenile male American mink ( Neovison vison ) using in vitro and in vivo (whole animal) experimental approaches. In vitro studies on cortical brain tissues revealed that inorganic Hg (HgCl 2 ; IC50 = 0.5 ± 0.2 µM) and methyl Hg (MeHgCl; IC50 = 1.6 ± 0.2 µM) inhibited glutamic acid decarboxylase (GAD; EC 4.1.1.15) activity. There were no Hg-related effects on [ 3 H]-muscimol binding to GABA(A) receptors (IC50s > 100 µM). HgCl 2 (IC50 = 0.8 ± 0.3 µM) but not MeHgCl (IC50 > 100 µM) inhibited GABA-transaminase (GABA-T; EC 2.6.1.19) activity. In a whole animal study, neurochemical indicators of GABAergic function were measured in brain regions (occipital cortex, cerebellum, brain stem, and basal ganglia) of captive mink fed relevant levels of MeHgCl (0 to 2 µg/g feed, ppm) daily for 89 d. No effects on GAD activity were measured. Concentration-dependent decreases in [ 3 H]-muscimol binding to GABA(A) receptors and GABA-T activity were found in several brain regions, with reductions as great as 94% (for GABA(A) receptor levels) and 71% (for GABA-T activity) measured in the brain stem and basal ganglia. These results show that chronic exposure to environmentally relevant levels of MeHg disrupts GABAergic signaling. Given that GABA is the main inhibitory neurotransmitter in the mammalian nervous system, prolonged disruptions of its function may underlie the sub-clinical impacts of MeHg at relevant levels to animal health.

Muskrat ( Ondatra zibethicus ) decline after the expansion of American mink ( Neovison vison ) in Poland

Abstract: Field survey data in Central Poland revealed that the proportion of sites inhabited by muskrats decreased from 44% to 7% over one decade. This corresponded to the decline in hunting bags of muskrat over the whole of Poland. The largest hunting harvest of muskrat was recorded in 1987/1988 (66,416 individuals), the smallest in 2007/2008 (4,567 individuals). The decline in hunting bags occurred in all regions analysed; however, it was most rapid in the north and north-east. Before the expansion of mink, which started in northern Poland at the beginning of the 1980s, muskrat densities in particular regions depended on the availability of aquatic habitats. A comparison of hunting bags of muskrat and American mink in years 2002-2008 indicated a signifi- cant negative correlation between the numbers of these two species harvested in seven regions of Poland. The negative correlation between numbers of muskrat and mink suggests that mink predation is one of the most important factors in the decline of the muskrat population in Poland.

Rapid Development of Fasting-Induced Hepatic Lipidosis in the American Mink ( Neovison vison ): Effects of Food Deprivation and Re-Alimentation on Body Fat Depots, Tissue Fatty Acid Profiles, Hematology and Endocrinology

Abstract: Hepatic lipidosis is a common pathological finding in the American mink (Neovison vison) and can be caused by nutritional imbalance due to obesity or rapid body weight loss. The objectives of the present study were to investigate the timeline and characterize the development of hepatic lipidosis in mink in response to 0-7 days of food deprivation and liver recovery after 28 days of re-feeding. We report here the effects on hematological and endocrine variables, body fat mobilization, the development of hepatic lipidosis and the alterations in the liver lipid classes and tissue fatty acid (FA) sums. Food deprivation resulted in the rapid mobilization of body fat, most notably visceral, causing elevated hepatosomatic index and increased liver triacylglycerol content. The increased absolute amounts of liver total phospholipids and phosphatidylcholine suggested endoplasmic reticulum stress. The hepatic lipid infiltration and the altered liver lipid profiles were associated with a significantly reduced proportion of n-3 polyunsaturated FA (PUFA) in the livers and the decrease was more evident in the females. Likewise, re-feeding of the female mink resulted in a more pronounced recovery of the liver n-3 PUFA. The rapid decrease in the n-3/n-6 PUFA ratio in response to food deprivation could trigger an inflammatory response in the liver. This could be a key contributor to the pathophysiology of fatty liver disease in mink influencing disease progression.

Behavioural responses of invasive American mink Neovison vison to an eradication campaign, revealed by stable isotope analysis

Abstract: Summary 1. The detrimental impacts of invasive, non-native species on islands are widely acknowledged and it is often best to act rapidly against such species, even where uncertainty exists over the best way to proceed. If management actions are evaluated and refined, using information learnt from the biology of culled animals, this uncertainty can be gradually reduced, increasing the likelihood of a successful outcome. 2. American mink Neovison vison carcasses were collected as part of an eradication campaign on several islands of the Outer Hebrides, Scotland, and stable isotope analysis was used to describe ecological variation in this invasive non-native predator. 3. Isotope profiles from individual mink whiskers demonstrated how behaviour at a population level changed markedly over time. As the eradication campaign progressed, mink increased their reliance on marine food sources and focused their activity on the coastline. Stable isotope analyses also demonstrated sex-related changes in foraging and ranging behaviour in relation to food resource availability on the two main island complexes. 4. Synthesis and applications. Our findings contribute to the refinement of a campaign to extend the successful eradication of mink from Uist and Harris, to the whole of the Outer Hebrides archipelago, UK. They also highlight the potential for stable isotope approaches to provide more detailed postmortem information that can inform adaptive management of wildlife populations for conservation objectives.

Gender differences in activity patterns of American mink Neovison vison in Germany

Abstract: Circannual and circadian activity patterns of American mink Neovison vison were studied in a fishpond area in northern Germany. Fourteen mink were radiotracked, nine of them (five males, four females) for at least 6 months, some of them even up to 21 months. Both sexes have reduced activity rates in winter months and showed a considerable increase of activity during mating season (March). In summer months—during the pup raising period—female activity continued to be high. Male mink, on the other hand, were less active with the exception of August and September. During this time, dispersal of juveniles takes place with resident males increasingly having to defend their territories. Circadian activity rhythms differed markedly between sexes. All investigated females exhibited a perennial diurnal pattern. Female activity during twilight and night was significantly lower than during daylight. Three investigated male mink showed a typical nocturnal course throughout the year. Daylight activity of these animals was very low, increased during dusk and dawn activity rates and stayed at a higher level during the night. Two males behaved arrhythmic; they did not prefer any time of the day for activity. The observed temporal strategies were discussed in context of intra-sexual territoriality, sexual dimorphism in body size and different environmental factors.

Pandemic (H1N1) 2009 in skunks, Canada.

Abstract: To the Editor: In March 2009, a novel influenza virus A (H1N1) emerged in Mexico, and, because of widespread human-to-human transmission, a global pandemic was declared in June 2009 (1). Although most cases have involved humans, pandemic (H1N1) 2009 has sporadically infected swine and turkeys and has also been reported in a small number of pet ferrets, cats, and captive cheetahs, and in a dog (2). Many of these animals were cared for by persons who experienced influenza-like illness and the owner of 1 cat who died had confirmed pandemic (H1N1) 2009 respiratory disease before the cat became ill, which suggests probable human-to animal-transmission of the virus (2). During mid-December 2009–mid-January 2010, eight striped skunks (Mephitis mephitis) died on a mink farm near Vancouver, British Columbia, Canada. On January 12, 2010, two of the skunks were brought to the Animal Health Centre in Abbotsford, British Columbia, for postmortem examination. One skunk exhibited purulent nasal exudates. In both skunks, investigators observed splenomegaly and severe pneumonia, characterized by heavy, dark red to purple, lung lobes involving >70% of the lung field. Microscopic examination showed moderate rhinitis and severe bronchopneumonia with intralesional bacteria, areas of interstitial pneumonia, and occasional nematode larvae. Also observed were splenic extramedullary hematopoiesis, plasmacytosis of both lymph nodes and spleen, and mild plasmacytic glomerulonephritis with proteinuria. Routine bacteriologic culture of lung showed heavy growth of Streptococcus dysgaslactiae subsp. equisimilis, Staphylococcus aureus, and Hafnia alvei. That death was caused by uncomplicated mixed bacterial bronchopneumonia in 2 (and possibly up to 8) adult skunks over a 6-week period was considered unlikely. The presence of lungworm was considered incidental. However, the areas of interstitial pneumonia suggested that a primary viral pathogen was likely. Molecular testing was conducted initially on fresh lung, liver, kidney, and spleen for canine distemper virus and, subsequently, for influenza A virus. The splenic and nodal plasmacytosis and plasmacytic glomerulonephritis also prompted testing for Aleutian disease virus (ADV). Organ samples were negative for canine distemper virus and positive for ADV. Detection of influenza A virus nucleoprotein and matrix genes and hemagglutinin and neuraminidase typing was performed with real-time reverse transcription–PCR. Organ samples were positive for pandemic (H1N1) 2009, which was confirmed by sequence analysis of DNA fragments obtained in the hemagglutinin, neuraminidase, and matrix gene testing. Primary viral interstitial pneumonia is frequently complicated by opportunistic bacterial bronchopneumonia and influenza virus A infection has been shown to predispose to pulmonary bacterial toxicity (3). Thus, we concluded that primary pandemic (H1N1) 2009 interstitial pneumonia had predisposed the 2 skunks to mixed bacterial bronchopneumonia and death. The skunks were also infected with ADV, presumably as a result of viral shedding by the minks, which are known to be ADV carriers. Striped skunks can be experimentally infected with ADV, and antibodies to ADV have been detected in wild skunks (4). Although ADV does not cause pneumonia (4), co-infection with ADV and influenza A virus is associated with higher mortality rates in minks with respiratory disease (5). Thus, ADV co-infection may have contributed to the severity of the pneumonia and the death of the skunks. The source of the pandemic (H1N1) 2009 virus is unclear. Nasal discharge was also observed in many of the minks, which suggests that they had a respiratory viral infection. However, no diagnostic workup was undertaken. Although severe outbreaks of interstitial pneumonia on mink farms can occur (6), most natural influenza A virus infections in minks are either mild or asymptomatic (5). Thus, the minks may also have been infected with pandemic (H1N1) 2009. Many of the pandemic (H1N1) 2009 infections reported in animals are believed to have been the result of exposure to infected humans (2). Workers on the mink farm did not experience influenza-like illness. However, humans with asymptomatic pandemic (H1N1) 2009 infection may have transmitted it to the mink. Because the skunks visited the mink farm daily, transmission of pandemic (H1N1) 2009 from humans to minks to skunks is a possibility. In view of the detection of pandemic (H1N1) 2009 virus in 2 striped skunks with fatal pneumonia, this species should now be regarded as a potential source of influenza A virus. Wild animals participate in the transmission of influenza A viruses between species, and the presence of wildlife on farms is known to be a risk factor for infection of poultry (7). Similar to raccoons, skunks express both α2,3 and α2,6 sialic acid receptors for avian and human influenza viruses in the respiratory tract (M. Shrenzel, San Diego Zoo, pers. comm.), which is believed to create the opportunity for mixed influenza infections with potential for genetic reassortment (8). Skunks, like raccoons, are highly mobile animals with large home ranges in rural and urban areas, which provides numerous opportunities for influenza A virus exposure and transmission to poultry, livestock, pets, and, ultimately, humans. The inclusion of striped skunks in wildlife influenza surveillance programs may be warranted.

Effect of late gestation low protein supply to mink (Mustela vison) dams on reproductive performance and metabolism of dam and offspring.

Abstract: Protein malnutrition in utero that induces permanent changes in metabolism has been investigated intensively in various animals in recent years, but to the best of our knowledge, not yet in the mink, a strict carnivore. In the present study, minks were fed either a low-protein (LP) diet, i.e., with a protein:fat:carbohydrate ratio of 14:51:35% of metabolisable energy (ME), or an adequate-protein diet (AP), i.e. 29:56:15% of ME, from when implantation was completed until parturition (17.9 +/- 3.6 days). Respiration and balance experiments were performed during both gestation and lactation. Plasma concentrations of leptin, IGF-1, and insulin were determined by radioimmunoassay; the relative abundances of glucose-6-phosphatase (G-6-Pase), fructose-1,6-bisphosphatase (Fru-1,6-P2ase), phosphoenol-pyruvate carboxykinase (PEPCK), and pyruvate kinase (PKM2) were determined in liver, and abundances of adiponectin and leptin in adipose tissue were determined by real-time quantitative PCR (q PCR). The protein supply only affected quantitative metabolism traits during the period of differentiated feeding. The dietary composition was reflected in the nitrogen metabolism and substrate oxidation, but no effects remained during lactation. The LP dams tended to have a smaller liver mass in relation to body weight than did AP dams (2.5% vs. 2.9%; p = 0.09), significantly less leptin mRNA (p < 0.05), and 30.6% fewer kits per mated female (p = 0.03). Furthermore, F1-generation kits exposed to protein restriction during foetal life (FLP1; 10.3 g) had a lower birth weight (p = 0.004) than did F1-generation kits exposed to adequate protein (FAP1; 11.3 g). Differences remained significant until 21 days of age (120.4 g vs. 127.6 g; p = 0.005). The FLP1 foetuses displayed a lower abundance of Fru-1,6-P2ase mRNA (p = 0.007) and of PKM2 mRNA (p = 0.002) than did FAP1 foetuses. Whether these changes during foetal life cause permanent changes in the glucose homeostasis of the offspring and result in the transmission of epigenetic phenotypic changes, as seen in the rat, needs further investigation.

Assessing the control/eradication of an invasive species, the American mink, based on field data; how much would it cost?

Abstract: Biological invasions are an important cause of biodiversity loss, American mink being one of the worst invasive species in Europe. We performed a 13-week control program of the species in the Butron river system (Northern Spain), where a natural population of the European mink is found. Three population estimates were considered: an absolute minimum, an intermediate scenario and a pessimistic one (n = 35, 49 and 70 animals, respectively). After 2,242 cage trap-nights, trapping success varied from 44 to 89% of these estimates. In addition, we evaluated the costs of eradicating the estimated populations; costs ranged between 652.5 and 2,970 € per mink, and would rise up to 83,462 € for the intermediate estimate under an exponential function linking captures and costs, or ca. 172.500 € to capture the highest estimate under a log-function. The implications of these numbers for the design and implementation of future control projects are discussed.

Abundance and habitat preferences of the southernmost population of mink: implications for managing a recent island invasion

Abstract: Since 2001 invasive American mink has been known to populate Navarino Island, an island located in the pristine wilderness of the Cape Horn Biosphere Reserve, Chile, lacking native carnivorous mammals. As requested by scientists and managers, our study aims at understanding the population ecology of mink in order to respond to conservation concerns. We studied the abundance of mink in different semi-aquatic habitats using live trapping (n = 1,320 trap nights) and sign surveys (n = 68 sites). With generalized linear models we evaluated mink abundance in relation to small-scale habitat features including habitats engineered by invasive beavers (Castor canadensis). Mink have colonized the entire island and signs were found in 79% of the surveys in all types of semi-aquatic habitats. Yet, relative population abundance (0.75 mink/km of coastline) was still below densities measured in other invaded or native areas. The habitat model accuracies indicated that mink were generally less specific in habitat use, probably due to the missing limitations normally imposed by predators or competitors. The selected models predicted that mink prefer to use shrubland instead of open habitat, coastal areas with heterogeneous shores instead of flat beaches, and interestingly, that mink avoid habitats strongly modified by beavers. Our results indicate need for immediate mink control on Navarino Island. For this future management we suggest that rocky coastal shores should be considered as priority sites deserving special conservation efforts. Further research is needed with respect to the immigration of mink from adjacent islands and to examine facilitating or hampering relationships between the different invasive species present, especially if integrative management is sought.

Relative abundance of culled and not culled American mink populations in northeast Spain and their potential distribution: are culling campaigns effective?

Abstract: The effectiveness of culling campaigns to eradicate or limit populations of the alien, invasive American mink in Catalonia was studied by comparing the annual relative abundance of culled versus non-culled populations. We selected three populations that were culled under government campaigns and a fourth that served as a control and hence was left undisturbed (not culled). The study took place between 2002 and 2006 and annual relative abundances were estimated from trapping with bankside traps. The abundance of all four populations remained relatively stable throughout the study period. However, the annual relative abundance of the culled populations was lower than that of the non-culled population, which indicates that culling may have lowered the densities of mink, although eradication was not achieved. We also determined the potential distribution of the American mink in Catalonia by means of a habitat suitability model. The final aim was to assist in planning this species’ management. Almost all watercourses in Catalonia were identified as suitable for the American mink, with preferred areas located in the northeast. We recommend that the government and administrations promote culling campaigns focused on limiting the spread of the American mink as eradication is likely to be difficult to be achieved under the current situation. Target areas should be located on the edges of the American mink’s range and should be prioritized to limit the spread of this species to areas in which there are endangered native species.

Outbreak of Neonatal Diarrhea in Farmed Mink Kits (Mustella vison) Associated With Enterotoxigenic Staphylococcus delphini

Abstract: An outbreak of diarrhea on a large commercial mink farm affected 5,000 of 36,000 neonatal mink kits, with 2,000 dying within a 2-week period. Affected kits were severely dehydrated, and their furcoats and paws were covered with yellow- to green-tinged mucoid feces. On necropsy, the small intestines of examined animals were markedly distended by serous to mucoid fluid. Microscopically, there was prominent colonization of the intestinal villar epithelium by gram-positive bacterial cocci in the absence of inflammation and morphologic changes in villous enterocytes. The colonizing bacteria were phenotypically identified as belonging to the Staphylococcus intermedius group of bacteria. This was confirmed by nucleic acid sequence analysis of the 16S ribosomal RNA gene. Further nucleic acid sequencing of polymerase chain reaction (PCR) amplicons from the superoxide dismutase gene and the heat shock protein 60 gene differentiated the isolate as Staphylococcus delphini. Production of staphylococcal enterotoxins A and E was demonstrated with a commercial ELISA-based immunoassay. Sequencing of PCR amplicons confirmed the presence of the enterotoxin E gene, but PCR amplification of the enterotoxin A, B, C, or D genes was not successful. Although direct causation was not confirmed in this study, the authors postulate that the observed hypersecretory diarrhea in these mink kits was the result of colonization of the small intestine by S delphini and subsequent production of enterotoxin.

Full genome comparison and characterization of avian H10 viruses with different pathogenicity in Mink (Mustela vison) reveals genetic and functional differences in the non-structural gene

Abstract: Background: The unique property of some avian H10 viruses, particularly the ability to cause severe disease in mink without prior adaptation, enabled our study. Coupled with previous experimental data and genetic characterization here we tried to investigate the possible influence of different genes on the virulence of these H10 avian influenza viruses in mink. Results: Phylogenetic analysis revealed a close relationship between the viruses studied. Our study also showed that there are no genetic differences in receptor specificity or the cleavability of the haemagglutinin proteins of these viruses regardless of whether they are of low or high pathogenicity in mink.

Leptospirosis in free-ranging endangered european mink (mustela lutreola) and other small carnivores (mustelidae, viverridae) from southwestern france

Abstract: To study the possible role of disease in the decline of endangered European mink (Mustela lutreola), we conducted a survey of antibody prevalence and renal carriage of pathogenic leptospira (Leptospira interrogans sensu lato) using serum and kidney samples collected from 1990 to 2007 from several free-ranging small carnivores and farmed American mink (Mustela vison) in southwestern France. An indirect microscopic agglutination test using a panel of 16 serovars belonging to 6 serogroups (Australis, Autumnalis, Icterohaemorrhagiae, Grippotyphosa, Panama, Sejroe) revealed antibodies in all species, with significant differences in antibody prevalences: 74% in European mink (n=99), 65.4% in European polecats (Mustela putorius, n=133), 86% in American mink (n=74), 89% in stone martens (Martes foina, n=19), 74% in pine martens (Martes martes, n=19), 35% in common genets (Genetta genetta, n=79), and 31% in farmed American mink (n=51). Serogroups Australis and Icterohaemorragiae were dominant in most free-ranging species; serogroup Grippotyphosa had high prevalences in European mink. Such high antibody prevalences have never been reported. They are probably related to the large number of known reservoirs, rats (Rattus spp.), muskrat (Ondatra zibethicus), and coypu (Myocastor coypu), in the study area. The polymerase chain reaction test specific for pathogenic leptospiral DNA detected renal carriage in 23% of 34 European mink, 22% of 18 polecats, and 15% of 33 free-ranging American mink, with no significant differences. Renal carriage shows that mustelids may shed leptospira for short periods, but their epidemiologic role is probably limited. High antibody prevalences suggest that the disease is unlikely to be highly pathogenic for these species; however, chronic forms of the disease (abortions, renal lesions) could reduce the reproductive success or life span of infected animals. Further studies on the pathogenicity of leptospirosis in these populations are needed to measure its impact on the population dynamics of these rodent predators.

Spatial distribution, activity, habitat selection of American mink (Neovison vison) and polecats (Mustela putorius) inhabiting the vicinity of eutrophic lakes in NE Poland

Abstract: Invasive American mink and native polecats were live-trapped over a period of six years and radio-tracked during one winter-spring season in the lakeside habitats in NE Poland. The number of mink declined whereas number of polecats was stable during 1995–2000, however, except during one winter, mink were always more abundant in the study area than polecats. Significant differences in habitat utilization between radio-collared mink and polecats were observed. Mink moved only along the lake shoreline and showed no seasonal shift in habitat selection. In winter, polecats were most frequently located close to the lake banks, but they also stayed in barns and stables. In spring, they moved further from the lakes. There was considerable interspecies overlap of mink and polecat home ranges in February, and common use of the banks of the 500 m long unfrozen canal was recorded for 4 mink and 5 polecats. The pattern of daily activity of polecat and mink differed: mink were most active at dawn and in early morning whereas polecats at dusk and in beginning of the night. Individuals of both species coexisted in this small area at relatively high densities and to some degree exploited the same habitats, particularly in the vicinity of sites with access to open water.

Differences in the ability to suppress interferon β production between allele A and allele B NS1 proteins from H10 influenza A viruses.

Abstract: In our previous study concerning the genetic relationship among H10 avian influenza viruses with different pathogenicity in mink (Mustela vison), we found that these differences were related to amino acid variations in the NS1 protein. In this study, we extend our previous work to further investigate the effect of the NS1 from different gene pools on type I IFN promoter activity, the production of IFN-β, as well as the expression of the IFN-β mRNA in response to poly I:C. Using a model system, we first demonstrated that NS1 from A/mink/Sweden/84 (H10N4) (allele A) could suppress an interferon-stimulated response element (ISRE) reporter system to about 85%. The other NS1 (allele B), from A/chicken/Germany/N/49 (H10N7), was also able to suppress the reporter system, but only to about 20%. The differences in the abilities of the two NS1s from different alleles to suppress the ISRE reporter system were clearly reflected by the protein and mRNA expressions of IFN-β as shown by ELISA and RT-PCR assays. These studies reveal that different non-structural protein 1 (NS1) of influenza viruses, one from allele A and another from allele B, show different abilities to suppress the type I interferon β expression. It has been hypothesised that some of the differences in the different abilities of the alleles to suppress ISRE were because of the interactions and inhibitions at later stages from the IFN receptor, such as the JAK/STAT pathway. This might reflect the additional effects of the immune evasion potential of different NS1s.

Neuropathologic features of Aleutian disease in farmed mink in Ireland and molecular characterization of Aleutian mink disease virus detected in brain tissues.

Abstract: A neuropathologic survey was conducted on mink brains from the 5 licensed mink farms in Ireland. The survey was part of a transmissible spongiform encephalopathy surveillance study. Aleutian disease (AD) was present on 4 of the 5 farms (80%). Neuropathologic features of nonsuppurative meningoencephalitis were common in mink from the 4 affected farms but were absent in the mink from the fifth farm, which was free of AD. The meningoencephalitis was characterized by infiltrates of lymphocytes and plasma cells, which were present in meninges, perivascular spaces, and the brain parenchyma. Fibrinoid necrotizing arteritis was seen in 11 mink brains, all of which were obtained from a single farm. Aleutian mink disease virus (AMDV) sequences for the capsid protein VP2 were obtained from brain samples from all affected farms. Although containing previously unreported amino acid residues, similarities with European and North American isolates were observed in the hypervariable regions within VP2, suggesting Irish AMDV is related to those isolates. The predicted amino acid residues, suspected of conferring pathogenicity at certain positions of the VP2 sequence, were present in the viral nucleic acid sequences.

Evidence of admixture between differentiated genetic pools at a regional scale in an invasive carnivore

Abstract: Invasive species represent a major threat to biodiversity, and the understanding of their population genetics is one of the most important goals in conservation biology. Recently, it has been proposed that methods using molecular tools could help define efficient eradication strategies and should be a preliminary step in the management process. The American mink was introduced in Europe for fur farming purposes in the 1920s, and, due to escapees, several feral populations have been mentioned in the last decades. In France, feral mink have been observed since the 1970s, and the largest population, located in Brittany, is considered to be still expanding. We investigated the genetic variability and population structure of 149 feral mink and 21 farmed mink from this area using six microsatellite loci. Our results showed three genetically distinct population units at the regional scale. A pattern of isolation by distance was observed for the whole sample. In our case we explain this pattern by recent admixture of the three genetic units. Our findings suggest that populations have recently met and started to homogenise.

Effects of Home-Range Characteristics on the Diet Composition of Female American Mink in the Baltic Sea Archipelago

Abstract: Predator home-range size may serve as a proxy of resource abundance and spatial structure of home range may also reveal information about diet composition of predators. We studied the diet of American mink Mustela vison, an introduced predator in Europe, to explore diet composition and to examine the association of diet with home-range characteristics. We collected scats of radio-tracked mink (two males and nine females) in summers 2004–2005 in the Archipelago Sea, SW Finland. The most important prey groups were fish (33% occurrence), birds (28%) and small mammals (mainly voles; 15%). The proportion of small mammals in female mink diet correlated positively with home-range size, which indicates that larger home ranges include larger islands, where vole populations are more persistent. Our results highlight the importance of fish as main prey for survival and invasion of mink in the outer archipelago, subsidising mink impact on other prey.

Behavioural responses of voles to simulated risk of predation by a native and an alien mustelid: an odour manipulation experiment

Abstract: Context. Potential mammalian prey commonly use the odours of their co-evolved predators to manage their risks of predation. But when the risk comes from an unknown source of predation, odours might not be perceived as dangerous, and anti-predator responses may fail, except possibly if the alien predator is of the same archetype as a native predator. Aims. In the present study we examined anti-predator behavioural responses of voles from the outer archipelagos of the Baltic Sea, south-western Finland, where they have had no resident mammalian predators in recent history. Methods. We investigated responses of field voles (Microtus agrestis) to odours of native least weasels (Mustela nivalis) and a recently invading alien predator, the American mink (Mustela vison), in laboratory. We also studied the short-term responses of free-ranging field voles and bank voles (Myodes glareolus) to simulated predation risk by alien mink on small islands in the outer archipelago of the Baltic Sea. Key results. In the laboratory, voles avoided odour cues of native weasel but not of alien mink. It is possible that the response to mink is a context dependent learned response which could not be induced in the laboratory, whereas the response to weasel is innate. In the field, however, voles reduced activity during their normal peak-activity times at night as a response to simulated alien-mink predation risk. No other shifts in space use or activity in safer microhabitats or denser vegetation were apparent. Conclusions. Voles appeared to recognise alien minks as predators from their odours in the wild. However, reduction in activity is likely to be only a short-term immediate response to mink presence, which is augmented by longer-term strategies of habitat shift. Because alien mink still strongly suppresses vole dynamics despite these anti-predator responses, we suggest that behavioural naivete may be the primary factor in the impact of an alien predator on native prey. Implications. Prey naivete has long been considered as the root cause of the devastating impacts of alien predators, whereby native prey simply fail to recognise and respond to the novel predation risk. Our results reveal a more complex form of naivete whereby native prey appeared to recognise alien predators as a threat but their response is ultimately inadequate. Thus, recognition alone is unlikely to afford protection for native prey from alien-predator impacts. Thus, management strategies that, for example, train prey in recognition of novel threats must induce effective responses if they are expected to succeed.

Different distribution of Cav3.2 and Cav3.1 transcripts encoding T-type Ca2+ channels in the embryonic heart of mice

Abstract: We investigated the distribution of T-type Ca(2+) channel mRNAs in the mouse embryonic heart. Cav3.2, but not Cav3.1, was expressed in the E8.5 embryonic heart along with cardiac progenitor markers (Nkx2.5, Tbx5, Isl-1) and contractile proteins (alpha and beta MHC). In the E10.5 heart, the distribution of Cav3.1 mRNA was confirmed in the AV-canal and overlapped with that of MinK or Tbx2. Cav3.2 mRNA was observed not only in the AV-canal but also in the outflow tract, along with MinK and Isl-1, indicating the expression of Cav3.2 in the secondary heart field. Thus, Cav3.2 may contribute to the development of the outflow tract from the secondary heart field in the embryonic heart, whereas Cav3.1 may be involved in the development of the cardiac conduction-system together with Cav3.2.

Habitat-mediated impact of alien mink predation on common frog densities in the outer archipelago of the Baltic Sea

Abstract: Alien predators have been recognised as one possible cause for amphibian declines around the world, but little is known of habitat-mediated predation impacts especially on adult amphibians. We studied common frog Rana temporaria under American mink Mustela vison predation in the outer archipelago of the Baltic Sea, south-western Finland. Using egg batches as an index of breeding frog female numbers we compared frog numbers and densities between a large, long-term mink-removal area and a comparable control area. Frog numbers in the removal area were at least 2.7-fold higher than those in the control area. In the presence of mink, frog densities increased with the amount of vegetation cover on the islands, indicating that mink predation affected frog densities especially on less-vegetated islands. An opposite trend appeared to be true for frogs in the mink-removal area, where other predators like snakes could induce a decline of frog densities on more vegetated islands. Shrub or grass vegetation seems to provide frogs shelter against alien mink predation. Our result highlights the importance of landscape-level habitat management as a conservation tool for amphibian populations.

Feeding mink (Neovison vison) a protein-restricted diet during pregnancy induces higher birth weight and altered hepatic gene expression in the F(2) offspring.

Abstract: Malnutrition during foetal life can induce modifications in the phenotype of an individual. The present study aimed to observe effects of low foetal life protein provision on modifications of the phenotype and changes in the progeny of 1-year-old female mink (F(1) generation) offspring of mothers fed a low-protein diet. Traits studied included reproductive performance, energy and protein metabolism, and key hepatic enzymes associated with glucose homeostasis and metabolic hormones. The F(0) generation offspring were fed either a low-protein (14 % of metabolisable energy (ME) from protein - FLP1) or an adequate-protein (29 % of ME from protein - FAP1) diet for the last 17.9 (sd 3.6) d of gestation. The F(1) dams were studied at birth and at 1 year of age, during their first reproductive cycle, after maintenance on an adequate diet from birth and thereafter. Metabolic traits during gestation and lactation were largely unaffected by foetal life protein provision, but birth weight in the F(2) generation was higher (P = 0.003) among FLP2 kits than among FAP2 kits. Furthermore, the relative abundance of pyruvate kinase mRNA was significantly (P = 0.007) lower, and fructose-1,6-bisphosphatase mRNA tended (P = 0.08) to be lower in FLP2 foetuses than in FAP2 foetuses, showing some similar difference in the F(2) generation and F(1) generation foetuses, suggesting an effect on some hepatic enzymes affecting glucose homeostasis being transmitted from the F(1) to the F(2) generation. These findings indicate that even though energy and nitrogen metabolism displayed no effect of protein provision during early life, programming effects still appeared at the molecular level in the following generation.