Showing papers on "Mink published in 1996"

Coassembly of K(V)LQT1 and minK (IsK) proteins to form cardiac I(Ks) potassium channel.

Abstract: THE slowly activating delayed-rectifier K+ current, IKS, modulates the repolarization of cardiac action potentials. The molecular structure of the IKS channel is not known, but physiological data indicate that one component of theIKSchannel is minK (refs 1–6), a 130-amino-acid protein with a single putative transmembrane domain7. The size and structure of this protein is such that it is unlikely that minK alone forms functional channels8,9. We have previously used positional cloning techniques to define a new putative K+-channel gene, KVLQT110. Mutations in this gene cause long-QT syndrome, an inherited disorder that increases the risk of sudden death from cardiac arrhythmias. Here we show that KVLQT1 encodes a K+ channel with biophysical properties unlike other known cardiac currents. We considered that KVLQT1 might coassemble with another subunit to form func-tional channels in cardiac myocytes. Coexpression of KVLQT1 with minK induced a current that was almost identical to cardiac IKS. Therefore, KVLQT1 is the subunit that coassembles with minK to form IKS channels and IKS dysfunction is a cause of cardiac arrhythmia.

Preliminary Observations on the Pathogenesis of Experimental Bovine Spongiform Encephalopathy

Abstract: Bovine spongiform encephalopathy (BSE), a scrapie-like or “prion” disease of domestic cattle first recognized in Great Britain in 1986 (1), has provided a precedent among such diseases in its occurrence as a nationwide food-borne epidemic originating from contamination of commercially processed feed with a scrapie-like agent (2–4). Although the precise routes of infection in previously described naturally occurring scrapie-like diseases of animals remain less clear, there is substantial epidemiologic evidence that transmissible mink encephalopathy (TME), a rare disease of ranch-reared mink, is also food-borne (5), and oral, or alimentary exposure, is generally considered a likely means of transmission of natural scrapie under field conditions (6–8). It seems probable also that lateral transmission, within captive populations, of chronic wasting disease of mule deer and Rocky Mountain elk (9) results from oral contamination.

Dietary Exposure of Mink to Carp from Saginaw Bay.

Abstract: In this study, mink (Mustela vison) were exposed to various amounts of carp (Cyprinus carpio) collected from Saginaw Bay, Lake Huron, MI, and the reproductive effects were observed. In this portion of the study, quantification of the dioxin-like activity was estimated by two different methods. One method was based on the relative potencies -Toxic Equivalency Factors (TEF) values- of individual Planar Halogenated Hydrocarbon (PHH) compounds and an additive model of toxicity to give toxic equivalents (TEQs). The other method utilized an in vitro bioasssay of the complex mixtures of PHHs found in the samples to directly quantify dioxin-like potency and is reported as tetrapchlorodibenzo-p-dioxin (TCDD)-EQ. This study was conducted to calibrate the HFIIE bioassay TCDD-EQ from an environmentally weathered PHH mixture to ecologically relevant end points in a sensitive species that occurs in the Great Lakes region.

Heparin Induces Dimerization and Confers Proliferative Activity onto the Hepatocyte Growth Factor Antagonists NK1 and NK2

Abstract: Hepatocyte growth factor (HGF) is a potent epithelial mitogen whose actions are mediated through its receptor, the proto-oncogene c-Met. Two truncated variants of HGF known as NK1 and NK2 have been reported to be competitive inhibitors of HGF binding to c-Met, and to function as HGF antagonists (Lokker, N.A., and P.J. Godowski. 1993. J. Biol. Chem. 268: 17145-17150; Chan, A.M., J.S. Rubin, D.P. Bottaro, D.W. Hirschfield, M. Chedid, and S.A. Aaronson. 1991. Science (Wash. DC). 254:1382-1387). We show here, however, that NK1 acts as a partial agonist in mink lung cells. Interestingly, NK1, which is an HGF antagonist in hepatocytes in normal conditions, was converted to a partial agonist by adding heparin to the culture medium. The interaction of NK1 and heparin was further studied in BaF3 cells, which express little or no cell surface heparan sulfate proteoglycans. In BaF3 cells transfected with a plasmid encoding human c-Met, heparin and NK1 synergized to stimulate DNA synthesis and cell proliferation. There was no effect of heparin on the IL-3 sensitivity of BaF3-hMet cells, and no effect of NK1 plus heparin in control BaF3 cells, indicating that the response was specific and mediated through c-Met. The naturally occurring HGF splice variant NK2 also stimulated DNA synthesis in mink lung cells and exerted a heparin-dependent effect on BaF3-hMet cells, but not on BaF3-neo cells. The activating effect of heparin was mimicked by a variety of sulfated glycosaminoglycans. Mechanistic studies revealed that heparin increased the binding of NK1 to BaF3-hMet cells, stabilized NK1, and induced dimerization of NK1. Based on these studies, we propose that the normal agonist activity of NK1 and NK2 in mink lung cells is due to an activating interaction with an endogenous glycosaminoglycan. Consistent with that model, a large portion of the NK1 binding to mink lung cells could be blocked by heparin. Moreover, a preparation of glycosaminoglycans from the surface of mink lung cells induced dimerization of NK1. These data show that the activity of NK1 and NK2 can be modulated by heparin and other related glycosaminoglycans to induce proliferation in cells expressing c-Met.

Dietary Exposure of Mink to Carp from Saginaw Bay. 3. Characterization of Dietary Exposure to Planar Halogenated Hydrocarbons, Dioxin Equivalents, and Biomagnification

Abstract: Mink are known to be very sensitive to the toxic effects of planar polychlorinated biphenyls (pPCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs), collectiv...

The Relationship between Capsid Protein (VP2) Sequence and Pathogenicity of Aleutian Mink Disease Parvovirus (ADV): a Possible Role for Raccoons in the Transmission of ADV Infections

Abstract: Aleutian mink disease parvovirus (ADV) DNA was identified by PCR in samples from mink and raccoons on commercial ranches during an outbreak of Aleutian disease (AD) Comparison of DNA sequences of the hypervariable portion of VP2, the major capsid protein of ADV, indicated that both mink and raccoons were infected by a new isolate of ADV, designated ADV-TR Because the capsid proteins of other parvoviruses play a prominent role in the determination of viral pathogenicity and host range, we decided to examine the relationship between the capsid protein sequences and pathogenicity of ADV Comparison of the ADV-TR hypervariable region sequence with sequences of other isolates of ADV revealed that ADV-TR was 94 to 100% related to the nonpathogenic type 1 ADV-G at both the DNA and amino acid levels but less than 90% related to other pathogenic ADVs like the type 2 ADV-Utah, the type 3 ADV-ZK8, or ADV-Pullman This finding indicated that a virus with a type 1 hypervariable region could be pathogenic To perform a more comprehensive analysis, the complete VP2 sequence of ADV-TR was obtained and compared with that of the 647-amino-acid VP2 of ADV-G and the corresponding VP2 sequences of the pathogenic ADV-Utah, ADV-Pullman, and ADV-ZK8 Although the hypervariable region amino acid sequence of ADV-TR was identical to that of ADV-G, there were 12 amino acid differences between ADV-G and ADV-TR Each of these differences was at a position where other pathogenic isolates also differed from ADV-G Thus, although ADV-TR had the hypervariable sequence of the nonpathogenic type 1 ADV-G, the remainder of the VP2 sequence resembled sequences of other pathogenic ADVs Under experimental conditions, ADV-TR and ADV-Utah were highly pathogenic and induced typical AD in trios of both Aleutian and non-Aleutian mink, whereas ADV-Pullman was pathogenic only for Aleutian mink and ADV-G was noninfectious Trios of raccoons experimentally inoculated with ADV-TR and ADV-Utah all became infected with ADV, but only a single ADV-Pullman-inoculated raccoon showed evidence of infection Furthermore, none of the ADV isolates induced pathological findings of AD in raccoons Finally, when a preparation of ADV-TR prepared from infected raccoon lymph nodes was inoculated into mink and raccoons, typical AD was induced in Aleutian and non-Aleutian mink, but raccoons failed to show serological or pathological evidence of infection These results indicated that raccoons can become infected with ADV and may have a role in the transmission of virus to mink but that raccoon-to-raccoon transmission of ADV is unlikely

Introduced carnivores in Europe with special reference to central and northern Europe

Abstract: The American mink Mustela vison, raccoon dog Nyctereutes procyonoides and raccoon Procyon lotor are introduced carnivores in Europe. The first American minks were brought to European fur farms in the late 1920s, when also the first raccoons were released, and raccoon dogs were released in the 1930s. The numbers of American minks and raccoon dogs increased rapidly, and today they are widely distributed in Europe. The range of the raccoon is restricted to Germany and adjacent countries and Belorussia. Minks are generalist predators whereas raccoon dogs and raccoons are omnivorous. Thus, e.g. birds and their eggs form part of the diet of these species. Minks are known to have caused damage to colonial ground-nesting sea-birds. Some bird populations have, however, adapted to the presence of mink in a few years. The American mink may also have played a role in the decline of the European desman Galemys pyrenaicus in Spain and the water vole Arvicola terrestris in England. It may also compete with the otter Lutra lutra, European mink Mustela lutreola and polecat M. putorius. Male American minks can mate with female European minks whose embryos may die. Hence, the American mink may be one of the reasons behind the decline of the European mink. Raccoon dogs can be locally harmful to waterfowl colonies and frogs, but their overall significance to the native fauna seems to be slight. Little is known about the predation or competition of the raccoon with the native fauna in Europe. The raccoon dog and raccoon can, however, be vectors of rabies; e.g. in Finland, the raccoon dog was the main vector of rabies during the epizootic in 1988-1989. The raccoon dog can also be a vector of e.g. sarcoptic mange and trichinosis.

The effect of domestication on brain size and composition in the mink (Mustela vison)

Abstract: The sizes of total brain, the five fundamental brain parts, and certain telencephalic structures were measured in wild mink (Mustela vison energumenos) and ranch mink of a Dark Standard strain of the same species. By means of intraspecific allometric methods for analysing the relationship between brain weight and body weight (net carcass weight), the volumes of the brain parts were compared in both groups. In general, total brain, as well as all the parts measured, were smaller in size in ranch mink independent of body size, age, and sex, indicating that domestication has led to a decrease in size. There were differences in the amount of decrease in various brain parts. These are discussed in connection with domestication time, with comparable results obtained in other species, and with regard to the functional importance of the brain parts.

Niche separation by mink and river otters : coexistence in a marine environment

Abstract: We studied habitat selection and niche separation by mink (Mustela vison) and sympatric river otters (Lutra canadensis) living in a coastal environment in Prince William Sound, Alaska, during summer 1991. We hypothesized that exposure to wave action, depth of tidal zone, substrate composition, and availability of cover were important habitat variables in selection of sites by mink at the terrestrial - marine interface. We also hypothesized that because of high resource abundance, little resource partitioning would occur between mink and river otters in the marine environment, leading to a large niche overlap. We employed step-wise logistic regression to develop a model separating feeding sites of mink, based on trails and latrines, from random sites. This model identified vegetated slope, tidal slope, overstory (old-growth forest), under-story (brush), small rocks, and exposure to wave action as the variables characterizing sites selected by mink. Mink selected (use > availability) shallow vegetated slopes and tidal slopes. Mink also selected sites that were more protected from wave action and with more overstory cover, but avoided (use < availability) beaches with small rocks as the main substrate, which is likely to be correlated with low availability of food. Analysis of niche overlap identified exposure and overstory as two variables that differ significantly between these two mustelids. Niche overlap including all habitat variables was 48%. Removal of exposure and overstory from this calculation resulted in 78.5% overlap. River otters selected sites with high exposure to wave action, whereas mink selected sites with low and medium exposure. Otters selected sites with high overstory cover, whereas mink showed less preference for such sites. Therefore, we have recorded niche separation in a marine environment, but were unable to attribute it to competition. Moreover, pronounced resource partitioning occurred even when food was abundant.

Distributional history of the American mink (Mustela vison) in Finland with special reference to the trends in otter (Lutra lutra) populations

Abstract: The distributional history of the American mink (Mustela vison) in Finland in 1951‐93 was studied by means of game inquiries and compared to the trends in otter (Lutra lutra) populations. Minks were brought to fur farms in the late 1920s and the first minks were observed in the wild in 1932. In the early 1950s minks occurred mainly in the western and southwestern coast of Finland, but two decades later minks were found in most parts of the country. Today minks are found almost everywhere in Finland; only few observers report that minks are not found in their area. The relative density of the mink is now highest in eastern Finland, rather high in southern Finland and quite low in Lapland. The data from the archipelago are, however, sparce. Otter density declined in the 1970s, but increased again in some areas in the 1980s, is now highest in the provinces of Kymi, Mikkeli and Central Finland, and almost lacking from SW Finland, especially from the coast. Among the reasons behind the decline in the otter populations may have been environmental pollutants, like dieldrin in inland areas and PCBs in the coast and archipelago. Human disturbance may also have had an effect, especially in the archipelago. The role of the mink is not clear; it seems probable that if there is competition between these species, the otter is the stronger one.

Growth and body size in populations of mink frogs Rana septentrionalis from two latitudes

Abstract: Age, longevity, and growth in mink frogs Rana septentrionalis from two latitudes in Quebec, Canada, were assessed by skeletochronological and back-calculation methods in order to document proximate causes for intraspecific variations in adult body size. In both study sites, females grew faster and were on average 11% larger than males. Mean age and maximal longevity were significantly higher in females than in males only in the southern populations. There was thus an interpopulation difference in the relative contribution of age and growth to sexual size dimorphisms. Sex-ratio also favored females (males suffering higher mortality) only in the southern populations. Specimens from the northern population had higher mean ages (but not higher longevities) and were 17% larger than specimens from the southern populations. Annual growth rate appeared similar at the two study sites despite a shorter growing season at the northern locality. Maturity was reached by both sexes after 1 yr of post-metamorphic life (PML) in the southern populations but after 2 yr of PML in the northern population. There are indications that tadpoles metamorphose at larger body size at the northern locality after a prolonged larval period. It is concluded that growth rate, delayed maturity, greater mean ages, and eventually size at transformation. all contribute to the larger size of adult mink frogs at northern localities.

Modulation of ecotropic murine retroviruses by N-linked glycosylation of the cell surface receptor/amino acid transporter.

Abstract: The cell surface receptor for ecotropic host-range (infection limited to mice or rats) murine leukemia viruses (MuLVs) is the widely expressed system y+ transporter for cationic amino acids (CAT-1). Like other retroviruses, ecotropic MuLV infection eliminates virus-binding sites from cell surfaces and results in complete interference to superinfection. Surprisingly, infection causes only partial (ca 40 to 60%) loss of mouse CAT-1 transporter activity. The NIH/Swiss mouse CAT-1 (mCAT-1) contains 622 amino acids with 14 hydrophobic potential membrane-spanning sequences, and it is known that the third extracellular loop from the amino terminus is required for virus binding. Although loop 3 is hypervariable in different species and mouse strains, consistent with its proposed role in virus-host coevolution, loop 3 sequences of both susceptible and resistant species contain consensus sites for N-linked glycosylation. Both of the consensus sites in loop 3 of mCAT-1 are known to be glycosylated and to contain oligosaccharides with diverse sizes (J. W. Kim and J. M. Cunningham, J. Biol. Chem. 268:16316-16320, 1993). We confirmed by several lines of evidence that N-linked glycosylation occludes a potentially functional virus-binding site in the CAT-1 protein of hamsters, thus contributing to resistance of that species. To study the role of receptor glycosylation in animals susceptible to infection, we eliminated loop 3 glycosylation sites by mutagenesis of an mCAT-1 cDNA clone, and we expressed wild-type and mutant receptors in mink fibroblasts and Xenopus oocytes. These receptors had indistinguishable transport properties, as determined by kinetic and voltage-jump electrophysiological studies of arginine uptake in oocytes and by analyses Of L-[3H]arginine uptake in mink cells. Bindings of ecotropic envelope glycoprotein gp7O to the accessible receptor sites on surfaces of mink cells expressing wild-type or mutant mCAT-1 were not significantly different in kinetics or in equilibrium affinities (i.e., K(D) approximately 3.7 X 10(-10) to 7.5 X 10(-10) M). However, when values were normalized to the same levels of mCAT-1 transporter expression, cells with wild-type glycosylated mCAT-1 had only approximately 50% as many sites for gp70 binding as cells with unglycosylated mCAT-1. Although infection with ecotropic MuLV had no effect on activity of the mink CAT-1 transporter that does not bind virus, it caused partial down-modulation of wild-type mCAT-1 and complete down-modulation of unglycosylated mutant mCAT-1. These results suggest that N-linked glycosylation causes wild-type mCAT-1 heterogeneity and that a significant proportion is inaccessible to virus. In part because only the interactive fraction of mCAT-1 can be down-modulated, infected murine cells conserve an amino acid transport capability that supports their viability.

Investigation of the pathogenesis of transplacental transmission of Aleutian mink disease parvovirus in experimentally infected mink.

Abstract: The transplacental transmission of Aleutian mink disease parvovirus (ADV) was studied in experimental infection of 1-year-old female non-Aleutian mink. The ADV-seronegative female mink were inoculated with ADV prior to mating or after the expected implantation of the embryos during pregnancy. A group of uninfected females served as a control group. Animals from each group were killed prior to or shortly after parturition. The in situ hybridization technique with radiolabeled strand-specific RNA probes was used to determine target cells of virus infection and virus replication. In both infected groups, ADV crossed the endotheliochorial placental barrier, although animals infected before mating already had high antibody titers against ADV at the time of implantation. The percentage of dead and resorbed fetuses was much higher in dams infected before mating. In the placentae of these mink, virus DNA and viral mRNA were detected in cells in the mesenchymal stroma of the placental labyrinth and hematoma but only occasionally in the cytotrophoblast of the placental hematoma. Placentae of animals infected during pregnancy showed in addition very high levels of virus and also viral replication in a large number of cytotrophoblast cells in the placental hematoma, which exhibited distinct inclusion bodies. In both groups, neither virus nor virus replication could be detected in maternal endothelial cells or fetal syncytiotrophoblast of the placental labyrinth. Fetuses were positive for virus and viral replication at high levels in a wide range of tissues. Possible routes of transplacental transmission of ADV and the role of trophoblast cells as targets for viral replication are discussed. Aleutian mink disease parvovirus (ADV) in adult mink causes a persistent infection usually followed by a chronic, progressive disease associated with a disorder of the immune system (2, 19, 33, 34, 36, 39), which is characterized by the development of plasmacytosis, hypergammaglobulinemia, and immune complex-mediated glomerulonephritis and arteritis in the chronic stage of the disease. Viral replication was demonstratedinlymphaticorgans,withapeak10daysafterinfection, but then rapidly decreased, and by 60 days after infection, viral replication was below detectable levels (2). Inminkkitsinfectedasnewborns,anacuteinterstitialpneu

Inhibition of minK protein induced K+ channels in Xenopus oocytes by estrogens.

Abstract: Previously it was shown that minK protein expression in uterus is regulated by estrogen. In the present study, we were interested in putative direct effects of estrogen on minK protein induced K+ currents (IminK) in Xenopus oocytes. Superfusion with 17-β-estradiol (1 μM) resulted in an inhibition of minK-induced currents, but had no appreciable effects on the delayed rectifier and inward rectifier K+ channels Kv1.1 and Kir2.1, respectively. The inhibition of IminK by 17-β-estradiol was concentration-dependent, with an IC50 of approximately 0.5 μM. In the presence of 17-β-estradiol, the conductance-voltage relationship was shifted to more depolarized potentials. IminK inhibition occurred also in the presence of the estrogen-receptor antagonist tamoxifen, suggesting that a mechanism independent of estrogen receptors is involved. The synthetic estrogen diethylstilbestrol (DES) also inhibited IminK but with a lower affinity (IC50 of 4.5 μM), while cortisol and progesterone had only weak effects on IminK. In summary, the results indicate that estrogens directly inhibit IminK.

Melatonin reduces mortality from Aleutian disease in mink (Mustela vison)

Abstract: Aleutian disease (AD) results from a persistent parvoviral infection that results in marked hypergammaglobulinemia and immune complex mediated lesions of the kidney, liver, lungs and, arteries. Melatonin protected both a wild type or demi strain and a demi/dark crossed strain of mink from AD. The biogenic amine also afforded protection against other non-diagnosed diseases naturally found on mink farms when it was available from a subcutaneously-placed reservoir. Some genetic strains of mink apparently differed in the resistance of mink to the virus and in the protective ability of melatonin. The demi strain was the most resistant followed by pastels, mahogany, darks, and those strains with the double recessive Aleutian gene. The protective action of melatonin appeared to result from melatonin's ability to scavenge free radicals, but it could also be due to the induction of antioxidant enzymes or to the modulation of immunity. Melatonin also protected mink against distemper.

Contaminant concentrations in Illinois mink and otter.

Abstract: Mink and otters are valuable wildlife resources and management efforts in North America and Europe have been directed towards re-establishing extirpated populations or expanding existing populations. The similarity of otter and mink habits and trophic status may allow inferences about the suitability of the habitat that is occupied by one species (mink) for the other species that is absent (otter). Remnant otter populations in Illinois have not expanded even though suitable habitat appears to be available and is occupied by mink. Low contaminant concentrations in tissues of mink trapped in a habitat where otters are not found and metal and organochlorine concentrations in tissues of otters incidentally collected by the Illinois Department of Natural Resources, suggest that environmental contaminants should not hinder natural expansion of otters in Illinois.

Identification of a DNA segment in ferret Aleutian disease virus similar to a hypervariable capsid region of mink Aleutian disease parvovirus.

Abstract: A 401bp DNA fragment of ferret Aleutian disease virus (ADV) was amplified using PCR primers spanning a hypervariable region of mink ADV capsid sequence. The amplified fragment was 88-89% homologous to the same region of previously known sequence of three different strains of mink ADV, however, as low as 54% homology was observed when compared with a 39bp segment known as hypervariable region. Within the predicted 13 amino acid hypervariable region, the ferret ADV sequence differed at 6 positions from the wild type mink Utah1 strain. Three amino acids Gln289, Glu293 and Thr295 in this region were common to the pathogenic ferret ADV, mink Utah1 and ADVK strains, but differed from the cell culture adapted nonpathogenic mink strain ADVG suggesting that these three conserved residues may have some functional significance.

Progression of Aleutian disease in natural and experimentally induced infections of mink.

Abstract: Objective To study temporal changes in amounts of viral DNA in blood leukocytes over long periods, and to determine whether severity of the disease is greater in experimentally induced, compared with natural, infection. Animals 18 naturally and 6 experimentally infected black mink; 26 naturally infected brown mink. Procedure Polymerase chain reaction amplification to detect viral DNA in blood and counter-immune electrophoresis to detect serum antibody were performed at regular intervals. Results In naturally infected black mink, amounts of viral DNA were initially high, but after the appearance of antibody, viral DNA fluctuated and, in some instances, was undetectable. In other mink, small amounts of viral DNA were infrequently detected during the course of the infection. Amounts of viral DNA in leukocytes in late stages of the disease correlated with renal lesions in brown mink, but black mink had more severe lesions associated with smaller amounts of viral DNA. Severity of the disease was not enhanced in experimentally inoculated black mink. Conclusions After infection, leukocyte viral DNA is initially present in large amounts, but, in most mink, decreases markedly in association with the appearance of antibody. There is no difference in the progression and severity of the disease between black mink infected experimentally or naturally. Transmission of the disease may be enhanced by use of contaminated toenail clippers for blood collection.

Effects of feeding and short-term fasting on water and electrolyte turnover in female mink (Mustela vison).

Abstract: Daily (24 h) rates of water and electrolyte turnover were measured in a conventional balance study in ten adult female pastel mink (Mustela vison) given free access to a standard mink feed for a 1-week conditioning period, followed by a 4 d experimental period and a 2 d fasting period. Drinking water was available throughout. In addition, the completeness of urine collection and the fraction of urine collected with the faeces were determined using a new experimental technique based on 24 h recoveries of specific urinary markers such as tritiated p-aminohippuric acid ([ 3 H]PAH) or 14 C-labelled inulin ([ 14 C]IN) continuously delivered by small Alzet® osmotic pumps implanted intraperitoneally. During feeding the mean individual percentage recovery in urine of [ 3 H]PAH released from the osmotic pumps ranged from 68 to 88 % (median 78 %). The mean percentage of urinary [ 3 H]PAH recovered from faecal collections was 6% (range 3-12%). In response to fasting the mean individual percentage recovery of [ 3 H]PAH in urine ranged from 62 to 78% (median 68 %). For urinary [ 14 C]IN the mean percentage recoveries in fed and fasted animals were 79 and 63% respectively. Furthermore, during fasting, withdrawal of the supplies of dietary water caused a slight but insignificant (P = 0.17) increase in the daily intake of drinking water and, hence, the animals maintained their normal water balance by a dramatic reduction in urine excretion (P<0.001). At the same time urinary solute excretion declined significantly (P < 0.001), due in part to the cessation of dietary electrolyte intake and in part to reduced formation of urea, whereas urinary osmolality decreased only moderately. The mean 24 h balances of Na, K, Ca, Mg, Cl and P were close to zero and only minor differences between the feeding and fasting periods were observed. When corrected for the measured inaccuracies in urine collection the balance data obtained in the present study represent useful reference standards for normally fed and fasted non-growing mink and, to some extent, useful guidelines for future studies in experimental animals.

2,2',4,5,5'-Pentachlorobiphenyl: comparative metabolism in mink (Mustela vison) and mouse.

Abstract: The metabolism of 14C-labeled 2,2‘,4,5,5‘-pentachlorobiphenyl was studied in mink (Mustela vison) and, for comparison, in the mouse (C57Bl). Both species were dosed orally and kept in metabolism cages for 5 days. Distribution in tissues and excretion rate were determined radiometrically, and metabolites were analyzed by GC/MS. Within 5 days, the mink excreted 17% of the dose, and the mouse excreted 74%, mainly via the feces. For both species, the excreted radioactivity consisted primarily of metabolites, a large proportion of which were covalently bound to macromolecules and to lipids. A smaller proportion consisted of water-soluble metabolites. Phenolic and, in trace amounts, methylsulfonyl metabolites were also excreted. In the mink, a salivary gland in the neck region demonstrated the highest concentration of radiolabeled material of all tissues examined (3 times higher than in adipose tissue and liver on a lipid weight basis). The radioactive material in the salivary gland consisted of the parent comp...

Establishment, maintenance, and transfection of totipotent embryonic stem cells from the embryos of domestic animals

Abstract: A method is described for establishing embryonic stem (ES) cell lines of domestic animals, such as cattle, sheep, goats, rabbits, and mink. Expanded blastocysts of the domestic animal are treated to remove the zonae pellucidae and then seeded onto a layer of feeder cells in a culture dish containing a suitable medium. The medium comprises plasma that is low in mitogens instead of serum that has undergone the clotting cascade. Addition of leukemia inhibitory factor (LIF), alpha-fetoprotein, and/or hyaluronic acid to the medium also improves the efficiency of establishing such ES cell line. Mink ES cell lines are prepared by pretreating blastocysts with prolactin to reactivate the blastocysts from embryonic diapause. Transfection of such ES cell lines and a composition for use in establishing embryonic stem cell lines are also disclosed.

Wildlife introductions to mammal-deficient areas: the Nordic countries

Abstract: Introduced mammals and birds have had a high rate of success in the Nordic countries. Out of 18 species new to the area, 14 (78%) have established a population in at least one country. American mink Mustela vison, raccoon dog Nyctereutes procyonoides, muskrat Ondatra zibethicus, white-tailed deer Odocoileus virginianus, Canada goose Branta canadensis and pheasant Phasianus colchicus have been the most successful exotics. Ecological effects caused by the newcomers include: displacement of European mink Mustela lutreola and beaver Castor fiber by American counterparts, changes in aquatic vegetation patterns caused by muskrat grazing, and locally heavy predation pressure on colonial waterbirds by the American mink. From now on, introductions of new species should be avoided, at least until proven harmless.

Effects of dietary exposure to fumonisins from Fusarium moniliforme culture material (M-1325) on the reproductive performance of female mink

Abstract: Adult female mink (Mustela vison) were fed diets that contained Fusarium moniliforme culture material that provided low- or high-dose dietary concentrations of 86 or 200 ppm fumonisin B1, 22 or 42 ppm fumonisin B2, and 7 or 12 ppm fumonisin B3, respectively, from approximately two weeks prior to breeding through gestation and lactation. Breeding performance of the females was not affected by consumption of the fumonisin diets. However, 58% of the mated females fed the high-dose diet (254 ppm total fumonisins) whelped compared to 100% of those fed the control and low-dose diets (115 ppm fumonisins). There was a statistically significant, dose-dependent decrease in kit (young mink) body weights at birth and a notable, but non-significant, decrease in litter size. The percentage of stillborn kits was directly proportional to the concentration of fumonisins in the dams' diets. Fumonisin concentrations in milk collected from those fed the high-dose diets were approximately 0.7% of the dietary fumonisin concentrations. Lactational exposure to fumonisins did not significantly decrease kit survival from birth through three weeks of age. Hepatic cell vacuolation was present in 25% of the control and 80% of the high-dose adults. No treatment-related gross or histologic lesions were observed in the kit mink. Numerous differences in hematologic and serum chemical parameters were noted between the control and fumonisin-exposed mink.

Immunotoxicity studies in mink (mustela vison) chronically exposed to dietary bleached kraft pulp mill effluent

Abstract: The immunotoxic potential of bleached kraft pulp mill effluent (BKME) to cell-mediated immunity in mink (Mustela vison) was investigated October 1993 through May 1994. For 26 weeks, 20 mink were fed a diet based upon fish caught within 6 km downstream of a bleached kraft mill in Saskatchewan, Canada. Water for this group contained 25% softwood-run BKME. Twenty control mink were fed nutritionally matched diets based upon fish from lakes receiving no municipal or industrial effluent and tap water. Using in vitro and in vivo immunotoxicity assays, the proliferative response of mink peripheral blood mononuclear cells (PBMC) to mitogens was optimal, at 72 hr with 10 jig/ml Concanavalin A, 1/80 dilution pokeweed mitogen, and 1/80 dilution phytohemagglutinin. Bacterial cell wall Escherichia coli lipopolysaccharide did not stimulate mitosis of the mink PBMC. No difference (P < 0.05) in PBMC proliferation was seen between the control and BKME-exposed mink with any of the mitogens used. Delayed type hypersensitivit...