Mercury and selenium in wild mink (Mustela vision) from Norway

Levels of mercury, methylmercuri and selenium were determined in liver samples from wild mink (Mustela vision) caught in the Norwegian countries of Rogaland (38 samples), Sogn og Fjordane (15 samples) and Hedmark (18 samples). The average mercury levels from these counties were 2.6, 3.1 and 2.1 micrograms Hg/g wet weight, respectively. No significant differences in mercury levels were found. The methyl mercury levels (MeHg) were determined in 30 samples. A very strong positive correlation between total mercury (Hg) and methyl mercury (r = 0.91, P less than 0.001) was found. The average methyl mercury level was 35 per cent of total mercury. This indicates that wild mink has the ability to demethylate mercury. The selenium levels were determined in 35 samples. A strong positive correlation between the levels of total mercury and selenium (r = 0.87, P less than 0.001) was found. There was no correlation between age or nutritional condition and mercury level. In the present study mink was examined to see of it could be recommended as an indicator species for monitoring the local environment for mercury contamination. No definite answer to this question could be found. The study did reveal, however, that in all the counties studied there are individuals that are considerably contaminated with mercury.     

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.     

Serum proteins in mink with endotoxin-induced amyloidosis and infectious plasmacytosis.

The serum proteins in Sapphire mink from the experimental and control groups in 2 endotoxin experiments and in a group of normal mink of the Standard type, were separated electrophoretically on cellulose acetate membranes.In experiment No. 1, in which the experimental mink were given repeated injections of endotoxin, and the controls were untreated, significantly increased total protein and significantly decreased albumin concentrations in the experimental group compared to the normal group were demonstrated. The concentration of the alpha₁-globulin was significantly elevated and the alpha₂-globulin significantly reduced in the experimental and the control groups compared to the normal group. Significant differences between the gamma-globulin concentrations in the various groups were not found.In experiment No. 2, all the animals were inoculated intraperitoneally with a crude tissue suspension containing the plasmacytosis agent 10 days before the experimental animals received the first of a series of injections with endotoxin. Significantly increased concentrations of total protein and gamma-globulin and significantly decreased albumin concentrations were, compared with the normal group, demonstrated in sera collected from the experimental group on the 94th, 201st and 254th day after the first injection of endotoxin. In the control group, compared with the normal group, significantly elevated concentrations of total protein, alpha₂-, beta- and gamma-globulins and significantly reduced albumin- and alpha₁-globulin were found but only in the second set of samples, while significantly decreased albumin- and significantly increased gamma-globulin concentrations were found in the third set.The results showed no significant differences between the gammaglobulin concentrations or between the other serum fractions in the experimental and the control groups in the 2 experiments. A possible explanation may be that there is no direct interrelationship between hypergammaglobulinaemia and amyloidosis, and that a common basic mechanism may stimulate related stem cells which thereafter differentiate in different ways.     

Nonsuppurative meningoencephalitis associated with Aleutian mink disease parvovirus infection in ranch mink.

Severe nonsuppurative meningoencephalitis associated with Aleutian mink disease parvovirus (ADV) infection was observed in adult ranch mink. Brain lesions included severe, locally extensive to coalescing lymphoplasmacytic meningoencephalitis with accompanying gliosis, satellitosis, and mild extension of inflammation into the leptomeninges. ADV was identified in mesenteric lymph node, spleen, brain, and liver of affected mink by polymerase chain reaction techniques. Sequences of the ADV isolate (TH5) revealed 2 unique residues in the region of the viral genome that determines pathogenicity. These findings suggest that certain strains of ADV may preferentially cause disease in the nervous system. ADV infection should be considered in the differential diagnosis of neurologic disorders in mink.     

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     

硒对汞致抗氧化系统损伤的拮抗作用

选用健康雏鸡250只作实验动物（对照组、中毒组、3个水平的硒保护组），研究汞对血液、组织中GSH－Px活性和LPO含量的影响以及硒与汞之间的相互作用效应。实验结果表明：汞可显著降低血清、组织中GSH－Px活性（P＜0.01），引起动物组织器官脂质过氧化，致使血清、组织中LPO含量显著增高（P＜0.01），且有时间－效应关系。从而说明汞能降低机体的抗氧化功能，损伤抗氧化系统；硒对汞致抗氧化系统的损伤具有拮抗作用。     

A note on diseases of mink.

The paper describes in brief the findings in 5,616 autopsies of adult mink, performed at the Institute of Pathology-CIC, La Plata, during the last five years. Nearly all these carcasses, coming from the most important ranches, were examined bacteriologically and histopathologically. Observations about the incidence of different causes of death, its distribution annually and prophylactic measures were reported. It concludes that Aleutian disease is the most important cause of death and produces severe economic losses.     

Lactic acid bacteria for mink. Colonization and persistence of Enterococcus faecium Cernelle 68 in the digestive tract of mink.

A method was developed to follow a lactic acid bacterial strain, Enterococcus faecium Cernelle 68, with respect to adhesion, multiplication, colonization, and persistence in the digestive tract of mink. Also the spread of the strain in the cage was examined. When adding 5 x 10(9) c.f.u. of a rifampicin resistant mutant per kg feed, high viable counts were registered throughout the digestive tract, apart from the oesophagus. Counts were increasing in the aboral direction, suggesting some multiplication in the intestine. It was possible to detect the strain in the intestinal tract 4 days after discontinuation of administration. Neither culture nor scanning electron microscopy gave evidence to suggest that E. faecium Cernelle 68 adhered to the mucosa. The spread of the E. faecium strain was observed in the environment. Counts of E. coli, lactobacilli, staphylococci, and clostridia were low, and none of these bacteria were constant findings.     

Alterations of rat brain lipids in methyl mercury intoxication.

Lipid alterations due to experimental intoxication by methyl mercury were studied in rat brain. The methyl mercury was administered perorally as a hydroxide bound to bovine liver protein. The lipids were separated by thin layer chromatography and the fatty acids identified by gasliquid chromatography. The lipids studied included free fatty acids, cholesterol and the main phosphatidylesters, phosphatidylcholine and phosphatidylethanolamine.The methyl mercury treatment resulted in an increase in total brain lipids and palmitic acid (16:0) in the free fatty acid fraction. This increase is interpreted as the cellular response to compensate for the loss of membrane proteins known to take place in the brain due to methyl mercury intoxication.     

Astrovirus epidemiologically linked to pre-weaning diarrhoea in mink.

Diarrhoea and excessive secretion from the cervical apocrine glands in young, suckling mink kits is a well-known, but poorly defined, syndrome often referred to as "sticky", "greasy", or "wet" kits. We have performed a case-control study, at farm level as well as at mink kit level, in Denmark and Sweden to investigate whether enteric virus infections may be a risk factor in the development of pre-weaning diarrhoea. Tissue samples from the enteric tract of 180 sacrificed mink kits were analysed histologically. Faecal contents were examined by electron microscopy (EM). Astrovirus was detected in abundance and found to be a significant risk factor both at farm level (OR=21.60, p<0.001) and at mink kit level (OR=7.95, p<0.001). Other factors, i.e. low body weight, coccoid bacteria adherent to the enteric villi, and presence of calicivirus were also shown to increase the risk of pre-weaning diarrhoea, although with less impact than astrovirus.     

Campylobacter colitis in ranch mink in Ontario.

Outbreaks of colitis, where Campylobacter jejuni and Campylobacter coli were the only pathogens isolated occurred in weanling mink (Mustella vision) on two commercial mink ranches in Ontario. Lesions were restricted to the proximal colon and were characterized by multiple 1 mm focal or 1 mm linear erosions/ulcers in the region 2 cm distal to the ileal-colonic junction. Histological changes included thickening of the colonic mucosa, inflammatory cell infiltrate in the lamina propria and submucosa, cellular debris and inflammatory exudate within cryptal lumens and multiple areas of mucosal erosion/ulceration. Four C. jejuni negative mink were challenged with 5.1 X 10(9) colony forming units of C. jejuni by oral inoculation. Three of four experimentally infected mink developed diarrhea by day 4 postinfection with lesions grossly and microscopically similar to mink in the naturally occurring outbreak. Examination of lesions by transmission electron microscope failed to show evidence of C. jejuni invasion of intestinal epithelium. Feeding uncooked slaughterhouse chicken offal was the likely source of C. jejuni in the naturally occurring outbreaks.     

汞胁迫对4个草坪草、牧草品种幼苗生长和生理的影响

本研究以紫花苜蓿‘金皇后’（Medicago sativa‘Golden empress’）,多花黑麦草‘盛宴’（Lolium multiflorum‘Feast’）和紫羊茅‘传奇’（Festuca rubra‘Legend’）和‘派尼’（Festuca rubra‘Pernille’）为材料,以含0,30,60,90,120 mg·L^-1 HgCl₂的Hoagland营养液进行沙培盆栽试验,探究不同浓度汞胁迫对4个草种生长和生理的影响。结果表明：随着汞胁迫浓度的升高,4个品种的出苗率、株高、干重、叶面积、叶绿素含量、PS II原初光能转化效率（Fv/Fm）、根系活力和可溶性糖（soluble sugar,SS）含量均呈下降趋势,而丙二醛（malonaldehyde,MDA）含量却呈上升趋势;4个草种的耐汞性及对汞敏感的指标类型存在明显差异;中低浓度汞胁迫（30~60 mg·L^-1）下,各草种的出苗率、叶面积、株高、干重、根系活力较对照降幅较小;汞胁迫浓度大于90 mg·L^-1时,各草种的测定指标均开始急剧变化,出苗率、株高、干重、叶面积、根系活力、叶绿素含量、叶片SS含量均显著降低（P<0.05）,而MDA含量显著升高（P<0.05）。4个草种幼苗期耐汞性强弱依次为：‘派尼’>‘金皇后’>‘盛宴’>‘传奇’。本研究可为汞污染土壤植物修复时在植物材料选择方面提供科学参考。     

Poly IC therapy in aleutian disease of mink.

Twenty-four virgin female aleutian mink were infected with aleutian disease agent and after 24 hours, 12 of these were treated with a course of polyinosinic acid-polycytidilic acid (Poly IC) injections. After six weeks the gammaglobulin level was significantly lower in the treated group but at 12 weeks this difference was no longer present. Four of the treated mink had normal target organ histology when killed at 20 weeks. The untreated group all showed moderate to marked changes but this difference was not statistically significant. There was a marked increase in the reactive lymphocyte blastogenesis index during the first weeks of infection and the phytohaemagglutinin response was seen to fall progressively. The antiglobulin reaction usually became positive after infection but neither antinuclear nor antierythrocyte antibodies were found. Precipitating antibodies to several polynucleotides were frequently present and were unrelated to infection or to Poly IC treatment.