A survey of Aleutian mink disease virus infection of feral American mink in Nova Scotia

Spleen samples from 14 mink that were trapped in 4 counties of Nova Scotia were tested for the presence of the Aleutian mink disease virus (AMDV) by polymerase chain reaction. Viral DNA was not detected in samples from Kings County (n = 2), but was detected in all the mink sampled from Colchester (n = 2) and Halifax (n = 6) counties, and 3 of 4 mink from Yarmouth County. The high level of AMDV-infected mink in Colchester and Halifax counties may pose a serious threat to the captive mink and wild animal populations. Because treatment of infected free-ranging mink is not an option, AMDV control strategies for the captive mink should be primarily focused on bio-security to protect clean ranches.     

The Effect of Experimental Methyl Mercury Poisoning on the Distribution of Acid Phosphatase During Autolysis in Cat Liver

Seven healthy male cats weighing between 2.35 and 4.30 kg were daily fed a diet which contained Hg²⁰³ labelled methyl mercury hydroxide in liver homogenate. Eight additional cats were kept as controls on a similar diet without methyl mercury hydroxide. The daily amount of methyl mercury hydroxide fed to the cats, expressed as inorganic mercury, varied between 3.75 and 4.33 mg per cat. When the animals had developed neurological symptoms typical of methyl mercury poisoning, they were decapitated and their livers removed for the determination of the mercury content, the distribution of acid phosphatase during autolysis at 37°G, the pH and the total bacterial count before and after a 24 hr. period of autolysis. Similar determinations except for the mercury were made from the livers of the control animals. The total amount of methyl mercury hydroxide fed to the cats varied between 29.14 and 40.12 mg Hg++ per kg of body weight, and the mercury content in their livers between 102.5 and 128.7 mg Hg++ per kg of liver wet weight.The share of un sedimentable activity of acid phosphatase out of the total immediately after decapitation was found to be significantly (P < 0.001) greater in the livers of the methyl mercury-fed cats than in the livers of the control animals. After 12 to 24 hrs. of autolysis at 37 °G the unsedimentable activity accounted for 100 % of the total acid phosphatase activity in the livers of 6 of the 7 methyl mercury-fed animals, while in the livers of the controls the corresponding percentages varied after 24 hrs. of incubation between 42 and 73, the mean being 57.4 ± 11.4 %. The mean pH of the livers of the methyl mercury fed animals was found to be significantly higher before (P< 0.001) and after (P < 0.001) a 24 hr. incubation at 37 °G than the corresponding mean pH values of the control animals.Because of the injection of antibiotics given to the cats before sacrifice the total bacterial count of the livers, which was checked before and after a 24 hr. incubation at 37°G, was found to be zero.     

Mercury and Mink. II. Experimental methyl mercury intoxication.

Adult female mink were fed rations containing 1.1, 1.8, 4.8, 8.3 and 15.0 ppm mercury as methyl mercury chloride over a 93 day period. Histopathological evidence of injury was present in all groups. Mink fed rations containing 1.8 to 15.0 ppm mercury developed clinical intoxication within the experimental period. The rapidity of onset of clinical intoxication was directly related to the mercury content of the ration. Mercury concentration in tissue of mink which died were similar, despite differences in mercury content of the diets and time of death. The average mercury concentration in the brain of mink which died was 11.9 ppm. The lesions of methyl mercury poisoning are described and criteria for diagnosis are discussed.     

The Effect of Experimental Methyl Mercury Poisoning on the Number of Sulfhydryl (SH) Groups in the Brain,Liver and Muscle of Rat

Fifteen adult male rats, the “experimental” rats, were fed a daily diet which contained methyl mercury hydroxide combined with liver homogenate. The daily dose of methyl mercury in terms of metallic mercury was 1.8 mg per rat. Six similar rats, the “controls”, were fed the same diet without methyl mercury. After the experimental rats had developed symptoms typical of methyl mercury poisoning, which occurred on the 15th day of the experiment, all the test animals were decapitated. The average total dose of methyl mercury producing toxic symptoms was 58,1 ± 6.1 mg Hg per kg body weight. The sulfhydryl groups and the mercury content of the brains, livers and caudal femoral muscles of the animals were determined. The SH determinations were made by amperometric titration and the mercury determinations by neutron activation analysis.The mean number of SH groups in the brains (14.95 ± 1.97 µM/g) and livers (35.89 ± 4.10 µM/g) of the methyl mercury-fed rats was found to be significantly (P < 0.001 and P < 0.01 respectively) lower than the corresponding means of the livers (17.63 ± 1.12 µM/g) and brains (44.75 ± 5.60 µM/g) of the controls. The number of SH groups in the muscles did not differ significantly between the animal groups (0.5 < P < 0.6). The mean mercury content of the brains, livers and muscles was found to be 26.0, 124.6 and 39.1 p.p.m. respectively, corresponding to 0.12, 0.62 and 0.19 µM per g of tissue. The decrease in the number of SH groups in the brains, 2.68 µM/g, and in the livers, 8.86 µM/g, of the methyl mercury-fed rats is thus considered to be due mainly to other effects of methyl mercury than to the direct binding of this compound to the tissue SH groups.     

Aleutian mink disease virus in furbearing mammals in Nova Scotia,Canada

Background

Aleutian mink disease virus (AMDV) is widespread among ranched and free-ranging American mink in Canada, but there is no information on its prevalence in other wild animal species. This paper describes the prevalence of AMDV of 12 furbearing species in Nova Scotia (NS), Canada.

Methods

Samples were collected from carcasses of 462 wild animals of 12 furbearing species, trapped in 10 NS counties between November 2009 and February 2011. Viral DNA was tested by PCR using two primer pairs, and anti-viral antibodies were tested by counterimmunoelectrophoresis (CIEP) on spleen homogenates.

Results

Positive PCR or CIEP samples were detected in 56 of 60 (93.3%) American mink, 43 of 61 (70.5%) short-tailed weasels, 2 of 8 (25.0%) striped skunks, 2 of 11 (18.2%) North American river otters, 9 of 85 (10.6%) raccoons, and 2 of 20 (10.0%) bobcats. Samples from six fishers, 24 coyotes, 25 red foxes, 58 beavers, 45 red-squirrels and 59 muskrats were negative. Antibodies to AMDV were detected by CIEP in 16 of 56 (28.6%) mink and one of the 8 skunks (12.5%). Thirteen of the mink were positive for PCR and CIEP, but three mink and one skunk were CIEP positive and PCR negative. Positive CIEP or PCR animals were present in all nine counties from which mink or weasel samples were collected.

Conclusions

The presence of AMDV in so many species across the province has important epidemiological ramifications and could pose a serious health problem for the captive mink, as well as for susceptible wildlife. The mechanism of virus transmission between wildlife and captive mink and the effects of AMDV exposure on the viability of the susceptible species deserve further investigation.     

Levels of mercury in samples of bees and honey from areas with and without industrial contamination]

Increasing numbers of specialists have been concerned with the problem of friendly environment in relation to man as well as to farm and wild animals. Greater interest in the biological monitoring of environment and ecosystem contamination can be observed. Determination of residues of organic and inorganic substances in bees (Apis mellifera) and in their products is one of effective possibilities of environmental pollution monitoring. Our work was aimed at the study of mercury levels in bees and their products. Mercury levels were determined in the head, abdomen and thorax of bees (Apis mellifera) from 20 bee populations coming from industrially contaminated areas with a dominant load of mercury (10 populations) and from uncontaminated areas. Mercury levels were determined simultaneously in honey coming from both contaminated and uncontaminated areas. The following mercury levels were found in bees from the contaminated area: heads 0.029-0.385 mg/kg, thorax 0.028-0.595 mg/kg and abdomen 0.083-2.255 mg/kg. Mercury levels in samples from uncontaminated areas ranged from 0.004 to 0.024 mg/kg in the heads, from 0.004 to 0.008 mg/kg in the thorax and from 0.008 to 0.020 mg/kg in the abdomen. In honey samples from the contaminated and uncontaminated areas mercury levels ranged from 0.050 to 0.212 mg/kg and from 0.001 to 0.003 mg/kg, respectively. The results of sample analyses for mercury loads in bees and honey from both contaminated and uncontaminated areas are given in Tab. I. Mean mercury levels in the single parts of the body in Apis mellifera and in honey from contaminated and uncontaminated areas are given in Figs. 1, 2, 3.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interrelationships between methylmercury exposure and selenium supplementation in cockerels using selected laboratory diagnostic parameters and toxicological parameters of residues]

A feed loading experiment was applied in 2 phases to 45 young cocks over 12 weeks, using 1,2-N,N-bis(methylmercury)-p-toluolsulphamide-dressed wheat (50% of base ration). Investigations were conducted to study the effects of selenium supplementation (0,2 mg Se as sodium selenite/l drinking water) on biochemical and hematological parameters (calcium, phosphorus, total protein, albumin, creatinine, urea, activity of alkaline phosphatase, hematocrit, hemoglobin, leucocyte count) as well as on parameters relating to toxicological residues (selenium and mercury levels in liver, musculature and kidneys). Statistically secured differences were found to exist between the experimental groups with regard to selenium and mercury in the liver and mercury concentrations in kidneys. Possible interrelationships were discussed.     

Experimental laboratory diagnostic and residual toxicological studies in young cocks after feeding mercury-disinfected seed with and without selenium supplementation

A feed loading experiment was applied in 2 phases to 45 young cocks over 12 weeks, using 1.2 (N, N-bis/methylmercury/-p-toluolsulphamide)-dressed wheat (50% of base ration). The experimental animals were White-Leghorn laying hybrids. Investigations were conducted to study the effects of exclusive exposure to mercury and those of mercury with addition of 0.2 mg of sodium selenite/l drinking water on biochemical parameters (calcium, phosphorus, total protein, albumin, creatinine, urea, activity of alkaline phosphatase, hematocrit, hemoglobin, and leucocyte count) as well as on parameters relating to toxicological residues (selenium and mercury levels in liver, musculature, and kidneys). Statistically secured differences were found to exist between the experimental groups with regard to selenium and mercury in the liver and mercury concentrations in kidneys. These data have shown that the problem of residualisation cannot be solved by selenium supplementation in parallel to methylmercury loading. The results recorded are likely to confirm the need for a general ban on feeding mercury-dressed seed.     

Lead and mercury residues in kidney and liver of Canadian slaughter animals.

Liver and kidney samples were collected from Canadian slaughter animals during the winter of 1973-1974. A total of 256 samples were analyzed for lead. Mean lead levels of 1.02 ppm in poultry liver, 1.04 ppm in bovine liver, 1.02 ppm in bovine kidney, 0.73 ppm in pork liver and 0.85 ppm in pork kidney were found. A total of 265 samples were analyzed for mercury. Mean mercury levels of 0.003 ppm in poultry liver, 0.007 ppm in bovine liver, 0.008 ppm in bovine kidney, 0.001 ppm in pork liver and 0.013 ppm in pork kidney were found. All levels detected were below the Canadian official tolerance of 2 ppm for lead and administrative tolerance of 0.5 ppm for mercury.     

Trichinella spiralis in wild animals, cats, mice, rats and farmed fur animals in Finland

A total of 1 399 samples of wild animals, cats, mice, rats and fur animals were examined for Trichinella larvae during the period 1.1.1982-30.6.1984. Samples were obtained both from the problem area, were Trichinella larvae had been found in pigs, and for comparison from the rest of Finland. The frequency of the infection in wild carnivores, badgers, pine martens, raccoon dogs, foxes and wild mink was significantly higher in the problem area than in the rest of Finland.     

Levels of trace elements in liver from Norwegian moose, reindeer and red deer in relation to atmospheric deposition

The levels of antimony, arsenic, cadmium, copper, lead, mercury, molybdenum, selenium and zinc were determined in liver of moose, reindeer and red deer from differen localities in Norway. Reindeer had considerably higher levels of mercury, lead and arsenic than moose and red deer. These findings are considered to be related to differences in feeding habits since reindeer on highland plateaus feed mainly on lichens which have been shown to accumulate trace elements. The levels of arsenic, and to some extent also selenium and cadmium, in moose and reindeer liver showed a north-south gradient closely related to the regional distribution of these elements in the forest moss. As regards lead, a north-south gradient and a relationship to moss levels, were found in moose liver only. It therefore seems that atmospheric deposition of the elements mercury, lead, arsenic, cadmium and selenium contribute to the body burden of these elements in cervides in Norway. There was no evidence of these elements accumulating to toxic levels.     

Vitamin E requirement of mink with special reference to tocopherol composition in plasma, liver, and adipose tissue

Tissue responses of 4 different tocopherols found in a basal diet (BD) and the effect of 2 physiologic levels of dl-alpha-tocopheryl acetate (25 and 150 mg/kg) on tissue tocopherol content were studied in the mink. The BD contained a total of 7.1 mg vitamin E/kg, with alpha-, beta-, gamma-, and delta-tocopherol in a ratio of 1:0.07:0.55:0.10, respectively. The corresponding ratios in the tissues were: liver, 1:0.04:0.12:0; plasma, 1:0:0.13:0; and adipose tissue, 1:0:0.19:0. After mink were fed diets containing vitamin E, alpha- and gamma-tocopherol were distributed in similar proportions in plasma and liver, but gamma-tocopherol was in a slightly higher proportion in adipose tissue. Addition of 25 or 150 mg/kg of alpha-tocopheryl acetate to the BD decreased the gamma-tocopherol levels in all 3 tissues; this was considered to be a dilution effect of other tocopherols in BD with added alpha-tocopheryl acetate. The beta-tocopherol content in the liver remained unchanged, irrespective of the dietary amount of alpha-tocopheryl acetate. Plasma alpha-tocopherol had a linear relationship to log dietary dose, with an apparent half-saturation of the vitamin E binding capacity at 13 mg vitamin E/kg diet. At the given dietary levels, liver and adipose continued to accumulate alpha-tocopherol. The correlation between total plasma lipids and plasma alpha-tocopherol was significant (P less than 0.001) only in the group fed the BD. Vitamin E analysis of plasma could be used as a routine method for controlling the vitamin E status of mink.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mink with Aleutian disease have autoantibodies to some autoantigens

Thirty mink infected with Aleutian disease virus (ADV) were found to have elevated levels of antibody to double-stranded DNA (dsDNA) in their sera when compared to 30 healthy mink. The anti-dsDNA antibody levels in the diseased mink were, however, not found to correlate with the total amount of immunoglobulin. This was a common observation for all autoantibodies tested. The concentration of rheumatoid factors of IgG class, but not those of IgM class, was found to be significantly higher in the diseased mink at the chosen level of significance (P less than 0.01). IgG antibodies to thyroglobulin were likewise significantly higher in the ADV-infected mink. Unexpectedly, we found IgG antibodies with specificities for cardiolipin and mitochondrial antigens to be significantly higher in healthy mink than in ADV-infected mink. This difference is especially remarkable since the serum immunoglobulin concentration of the ADV-infected mink was three times higher than the serum immunoglobulin concentration of the normal mink.     

水貂ASIP基因单倍型检测及其皮肤组织mRNA差异表达分析

试验旨在探究鼠灰色（agouti signaling protein，ASIP）基因单核苷酸多态性（single nucleotide polymorphisms，SNPs）形成的单倍型及皮肤组织差异表达mRNA对水貂被毛色素沉积的影响。通过PCR扩增、Sanger测序技术对金州黑水貂、红眼白水貂和名威银蓝水貂ASIP基因进行SNPs单倍型检测分析，利用实时荧光定量PCR技术检测3种毛色皮肤组织ASIP基因的表达量，分析单倍型及mRNA差异表达与毛色表型的相关性。结果表明，301个样本中共检测到10个SNPs，内含子2中4个SNPs （G18A、A159G、G235T、C1189T）共形成10种单倍型（Hap1~Hap10），其中Hap1（GAGC）和Hap2（GAGT）是3种不同毛色水貂群体的共享单倍型；部分内含子3中6个SNPs （C252T、A290C、G298C、A340G、T343C、T379C）形成4种单倍型（Hap1~Hap4），且Hap2（CCCGCC）是名威银蓝水貂群体的主体单倍型。5个位点（A290C、G298C、A340G、T343C、T379C）均处于完全连锁不平衡状态。实时荧光定量PCR检测显示，金州黑水貂和名威银蓝水貂ASIP基因mRNA表达量分别是红眼白水貂的1.25和0.95倍，三者间差异不显著（P>0.05）。研究结果初步提示，ASIP基因调控水貂不同毛色表型形成的分子机制可能存在差异。     

Trace element levels in liver and kidney from cattle, swine and poultry slaughtered in Canada.

Levels of arsenic, cadmium, copper, mercury and lead were determined in approximately 650 samples of liver and kidney from cattle, swine and poultry slaughtered in Canada during 1979-81. In addition zinc levels were determined in livers and kidneys from swine, and selenium and zinc levels were determined in the livers and kidneys from cattle. Depending on the element several methods of atomic absorption spectroscopy were used to analyze samples including flame, hydride generation, cold vapour generation and graphite furnace atomization. Analyses were also done by plasma emission spectroscopy. Levels of arsenic over 2.0 micrograms/g were detected in 0.9% of swine livers and 0.3% of swine kidneys. Cadmium levels higher than 1.0 micrograms/g were detected in 0.3% of cattle livers, 10.8% of cattle kidneys, 1.8% of swine kidneys, 0.4% of poultry livers and 0.3% of poultry kidneys. Levels of copper over 150 micrograms/g were detected in 0.4% of cattle and swine livers. Levels of lead over 2.0 micrograms/g were detected in 1.4% of poultry livers and 1.6% of poultry kidneys. The highest level of mercury detected in all species was 0.25 micrograms/g and the highest level of selenium was 1.9 micrograms/g. Zinc levels of over 100 micrograms/g were detected in 1.7% of cattle livers, 0.2% of cattle kidneys and 5.0% of swine livers.     

Selenium elimination in pigs after an outbreak of selenium toxicosis.

In May 1996, 150 grower pigs in 5 California counties were exposed to selenium-contaminated feed distributed by a single feed company. Feed samples from 20 herds had a mean selenium concentration of 121.7 ppm dry weight (range, 22.1-531 ppm). In San Luis Obispo County, 52 pigs in 24 herds were exposed to the feed, and 8 pigs died with signs of paralysis. Bilateral symmetrical poliomyelomalacia involving the ventral horns of the cervical and lumbar intumescence was evident on histologic examination of spinal cord from affected pigs. Of 44 surviving exposed pigs, 33 (75%) exhibited signs of selenosis, including anorexia, alopecia, and hoof lesions. Thirty-nine of 44 pigs (88.6%) had elevated (>1 ppm) blood selenium concentrations. Surviving exposed pigs were changed to a standard commercial ration containing approximately 0.5 ppm (dry weight) selenium. Blood selenium concentrations were determined weekly for 46 days following removal of the contaminated feed and were compared with values of 20 control pigs fed a standard commercial ration. Mean (+/-SD) blood selenium concentrations of exposed pigs were 3.2 +/- 2.6 ppm at the initial sampling and 0.4 +/- 0.1 ppm after 46 days. Mean blood selenium concentrations of < or = 0.3 ppm for control pigs at all samplings were significantly lower (P < 0.001) than concentrations for exposed pigs. Muscle and liver samples of 22 of the 44 exposed pigs were collected at slaughter approximately 72 days after withdrawal of the selenium-contaminated feed. Muscle samples had a mean selenium concentration of 0.36 ppm (wet weight). Liver samples had a mean selenium concentration of 1.26 ppm (wet weight). One liver sample had a selenium value in the toxic range for pigs (3.3 ppm wet weight; reference range, 0.4-1.2 ppm). A 1-compartment pharmacokinetic model of selenium elimination in exposed pigs was generated, and the geometric mean blood selenium elimination half-life was estimated to be 12 days. The 60-day withdrawal time recommended by the Food Animal Residue Avoidance Database was considered sufficient to allow safe human consumption of tissues from exposed pigs.     

Bull Spermatozoa under Mercury Stress

Defective sperm function is the most prevalent cause of male infertility and is difficult to treat. This study was designed to evaluate the effect of mercuric chloride (HgCl2) at 50-300 micromol/l concentration range, in vitro, on the sperm membrane and DNA integrity, viability, reduced glutathione (GSH) content and acrosomal status of the bull spermatozoa. The samples were processed for sperm analyses using semen-diluting fluid [phosphate-buffered saline (PBS), pH 7.2]. I recorded a meaningful increase in the lipid peroxidation (LPO) rate and a drastic fall in the spermatocrit values under mercury additions, dominantly at 300 microM mercury concentration, indicating a deleterious effect of mercury on the sperm membrane intactness. There was also a strong negative correlation between LPO rate and percentage of viable spermatozoa (r = -0.9, p < 0.001). GSH content was significantly impaired. Data obtained from Comet assay [single-cell gel electrophoresis (SCGE)] technique revealed that mercury is capable of inducing DNA breaks in the sperm nuclei. Interestingly, 90% of DNA breaks were double-stranded. The correlation between LPO rate and percentage of DNA breaks was found to be 0.9 (p < 0.001). Results of the gelatin test indicate that mercury is capable of altering the integrity of acrosomal membranes, showing an abnormal acrosome reaction. In this regard, a strong correlation was found between LPO rate and percentage of halos (r = -0.9, p < 0.001). In conclusion, mercury proved to be a potential oxidant in the category of 'environmental factors' to bull spermatozoa. Hence, considering the widespread use of mercury and its compounds, these metals should be regarded with more concern.     

The effect of ethionine feeding on the retention of a single per os dose of methyl mercury on rat

Six adult female rats were daily fed a diet containing DL-ethionine during three weeks. One daily rat dose was 30 mg of ethionine. Six similar rats, the controls, were kept on the same diet without ethionine. On the 21st day of the experiment all rats were given one dose of ²⁰³Hg labeled methyl mercury by stomach tube. Each rat received 163 µg in terms of metallic mercury. Ninety hrs. after the mercury administration all rats were sacrificed and the mercury contents of the brains, livers, caudal femoral muscles, erythrocytes and blood plasma were determined. The mean plasma mercury content was significantly (P<0.01) greater in the ethionine fed rats when compared to the controls.Keyword: methylmercury retention, ethionine     

Study of the soil-plant (carrot)-animal cycle of nutritive and hazardous minerals in a rabbit model.

Carrots were grown on soils polluted by heavy metal salts. Each particular microelement reached a high concentration [molybdenum (Mo) 39.00, cadmium (Cd) 2.30, lead (Pb) 4.01, mercury (Hg) 30.00, and selenium (Se) 36.20 mg/kg dry matter] in the carrot. In a metabolic balance trial conducted with 15 male and 15 female New Zealand White rabbits, the control animals (n = 5) were fed ad libitum with concentrate as basal diet, while the other rabbits received the basal diet and carrots containing the particular microelement. Blood samples were taken to determine the activity of serum enzymes. To investigate the metabolism of Mo, Cd, Pb, Hg and Se, samples were taken from the heart, liver, lungs, kidneys, spleen, ovaries/testicles, entire digestive tract, adipose tissue, femur, hair, faeces and urine. Carrot had significantly higher digestibility for all nutrients than the rabbit concentrate. Carrot samples of high Pb content had the lowest digestibility of crude protein. The microelements differed in their rate of accumulation in the organs examined: Mo and Cd accumulated in the kidneys, Pb in the kidneys, liver, bones and lungs, Hg in the kidneys and liver, while Se in the liver, kidneys and heart. The proportions of microelements eliminated from the body either via the faeces and urine (Mo 80.18% and Se 47.41%) or via the faeces (Cd 37.86%, Pb 66.39%, Hg 64.65%) were determined. Pathohistological examination revealed that the rate of spermatogenesis was reduced in the Mo, Cd, Pb and Hg groups compared to the control. Lead, Cd and Hg intake resulted in a considerable decrease in gamma-glutamyltransferase (GGT) and in an increase of alkaline phosphatase (ALP) activity because of damages to the kidneys and bones. All experimental treatments decreased the activity of cholinesterase (CHE) because of lesions in the liver.