In situ hybridization of GnRH mRNA in the rat and the mink hypothalamus using biotinylated synthetic oligonucleotide probes

The cellular localization of GnRH messenger RNA (mRNA) in the rat and the mink hypothalamus has been examined using a newly developed highly sensitive non-radioactive in situ hybridization procedure. Synthetic oligonucleotides labeled by addition of a biotin-21-dUTP tail at their 3' end can be used to detect GnRH mRNA in both species. Streptavidin-alkaline phosphatase revealed with nitroblue tetra-zolium-bromo-chloro-indolyl-phosphate as substrate makes possible detection of the biotinylated oligonucleotides. In the rat, our findings confirm results previously obtained using synthetic radioactive probes, and demonstrate the potency of and interest in using biotinylated oligonucleotides to identify related sequences of bases in tissues. The principle advantages include rapid signal detection, excellent spatial resolution, and low background. In the mink, the in situ hybridization method clearly confirms the characterization of GnRH-producing cells and also allows detection of GnRH cell bodies in conditions in which they are not detected by immunohistochemistry. Adaptation of the in situ hybridization to the detection of GnRH mRNA in species like the mink which shows seasonal reproductive activity is a crucial step. This method offers a new approach to problems as fundamental as changes in gene expression depending on photoperiod or under a variety of experimental conditions.

Effects of a technical PCB preparation and fractions thereof on ethoxyresorufin O-deethylase activity, vitamin A levels and thymic development in the mink (Mustela vison)

Clophen A50, a technical preparation of polychlorinated biphenyls (PCBs), was separated into four fractions; three containing chlorobiphenyls with 0, 1, or 2 to 4 ortho chlorines and one containing di- and tricyclic impurities such as naphthalenes and dibenzofurans. Clophen A50, the four fractions, and a synthetic mixture of the biologically most active non-ortho-chlorinated congeners (3,3',4,4'-tetra-, 3,3',4,4',5-penta-, and 3,3',4,4',5,5'-hexachlorobiphenyl), were separately mixed in the feed and given to female mink during the reproductive season. The concentration of a given compound in the feed mixture was equivalent to its concentration in the feed mixed with Clophen A50. Hepatic 7-ethoxyresorufin O-deethylase (EROD) activity in adults was enhanced 2-3 times by Clophen A50, the fractions containing non- or mono-ortho-chlorinated congeners, and the synthetic mixture. In neonatal kits delivered by females treated with non- or mono-ortho-chlorinated congeners, EROD was enhanced to about 30 times the control value. No live kits were delivered by the females treated with unfractionated Clophen A50. The fractions containing congeners with two to four ortho chlorines or di- and tricyclic compounds did not significantly induce EROD in either adults or kits. Clophen A50 reduced hepatic and pulmonary vitamin A contents in adult mink, while renal vitamin A was unaffected. Responses to the fractions containing the non- and mono-ortho-chlorinated congeners were similar to those obtained with Clophen A50. Their effects were, however, less pronounced, particularly with respect to the hepatic vitamin A reduction. The fractions containing congeners with two to four ortho chlorines and the di- and tricyclic compounds had no significant effects on tissue vitamin A contents.(ABSTRACT TRUNCATED AT 250 WORDS)

Toleration of high concentrations of dietary zinc by mink

Adult and kit male and female natural dark ranch mink (Mustela vison) were fed a conventional diet supplemented with 0, 500, 1,000, or 1,500 ppm zinc, as ZnSO4.7H2O, for 144 days. No marked adverse effects were observed in feed consumption, body weight gains, hematologic parameters, fur quality, or survival. Zinc concentrations in liver, kidney, and pancreas of the mink increased in direct proportion to the zinc content of the diet. Histopathologic examination of the livers, kidneys, and pancreata revealed no lesions indicative of zinc toxicosis. The results indicate that mink can tolerate at least 1,500 ppm dietary zinc, as ZnSO4.7H2O, for several months without apparent adverse effects.

Element concentrations in livers and kidneys of ranch mink

Reference ranges for element concentrations in livers and kidneys of "healthy" mink of known age, sex, and coat color and fed a conventional diet were determined. After euthanasia and removal of the pelts, liver and kidney samples were collected from 174 mink and analyzed for 22 elements using inductively coupled argon plasma emission spectroscopy. The diet of the mink was also analyzed for element concentrations. Descriptive statistics of element concentrations for livers and kidneys of the mink are given and compared with dietary element concentrations.

Immunohistochemical demonstration and radioimmunoassay of melatonin in the mink pineal gland

An antiserum raised against N-amino-3-propyl melatonin bound to a protein carrier was used to visualize melatonin by immunohistochemistry and to measure melatonin concentration by radioimmunoassay in the pineal gland of intact mink females killed throughout the 24 h cycle and females killed after a bilateral ablation of the cervical superior ganglion. Melatonin immunoreactivity revealed by immunofluorescence or by the peroxidase-antiperoxidase complex was observed in the cytoplasm of presumed pinealocytes of all the females. Circadian changes in pineal melatonin content were not visualized by immunohistochemistry; furthermore, immunoreactivity was also present in the pineal gland of the ganglionectomized females. However, the melatonin content measured by radioimmunoassay was significantly higher in the pineal gland from intact females killed during the night compared with that of intact females killed during the day or of ganglionectomized females. The discrepancy between the results obtained using the two methods may arise because immunohistochemistry can detect very small amounts of melatonin.

[Distribution of alpha 2M-globulin and Lpm-protein in the organs and tissues of the American mink]

Distribution in the organs and tissues of two proteins of alpha-macroglobulin fraction, that differ in their antigenic structures, has been studied in the American mink. The both proteins (alpha 2M and Lpm) are present in hepatocytes, in cells of the follicular epithelium of the ovary, in the thymic bodies, in the alveolar macrophages of the lungs and in the splenic lymphoid nodes. Joint localization of alpha 2M and Lpm is revealed in the connective tissue of all the organs examined. The exception make the stomach and the uterine, where alpha 2M is revealed but not Lpm. The results obtained demonstrate a similar distribution of the two alpha-macroglobulins in the mink organism. They correspond to the literature data on morphofunctional topography of alpha 2M in the man. Certain individual differences in alpha 2M and Lpm localization can reflect peculiarities inherent in each of these alpha-macroglobulins of the American mink.

Effects of diets containing sodium fluoride on mink

Mink (Mustela vison) kits still nursing, and adult male mink were fed diets containing various levels of fluorine (as NaF) to determine the effects on health, growth and pelt quality. Different groups were fed diets containing 25.5 (control), 46.0, 111.5 or 287.0 ppm fluorine (on a wet basis) for 7-8 mo. Gross, radiographic and microscopic changes were seen in bones from some animals ingesting the higher levels of fluorine. Chemical analyses for fluorine generally reflected levels ingested. Fluorine caused no detectable differences in pelt quality. After data were evaluated, tolerance levels in the feed of not more than 50 ppm fluorine for breeding stock and 100 ppm fluorine for animals being raised only for pelts are recommended.

Primary structure of duck amyloid protein A. The form deposited in tissues may be identical to its serum precursor

The amino acid sequence has been determined for the major protein that accumulates in amyloid fibrils in tissues of the Pekin duck. With the exception of 16 residues at the amino terminus, this 106-residue protein is homologous with human serum amyloid protein A (104-residue apoSAA), which is the putative precursor of the 76-residue protein that accumulates in human patients with amyloidosis. Duck serum is shown to contain a protein that is immunologically related and approximately equal in size (12 kDa) to the deposited form in ducks. These results indicate that proteolytic processing of the precursor is not a necessary step in the deposition of amyloid fibrils, at least in the duck.

Examination of mink (Mustela vison) fed a sulphuric acid preserved fish during lactation and growth period. I. A clinical-chemical examination

Addition of sulphuric acid preserved fish in great amounts as fur animal feed has a serious influence on the metabolism of the animals. The present experimental work shows that several clinical-chemical parameters are changed during feeding of acid preserved feed resulting in changes of the fluid-, electrolyte- and acid-base balance as well as in the immunological status. The changes are most probably due to changes also found in the organ functions. The present work together with earlier investigations by the authors has formed the scientific background for the use of acid preserved fish silage in mink during the last 10 years. This has made it possible to out-distance the competitors further, both with respect to fur quality and feeding costs.

Skin surface lipids of the mink

Skin surface lipids from mink (Mustela vison) were collected in acetone and analyzed by thin-layer chromatography and gas chromatography. The principal components were wax monoesters (92%), cholesteryl esters (5%), free fatty acids (1%), fatty alcohols (1%) and cholesterol (1%). The fatty acids and alcohols contained in these lipids were composed principally of homologous series of straight chained omega 7-unsaturated structures (C16-C24), accompanied by lesser proportions of homologous series of saturated (C14-C22) and omega 9-unsaturated (C18-C22) structures.

Efficiency of utilisations of food energy by female growing minks

The efficiency of utilisation of food energy by female growing minks, from weaning to adult age, was studied. The food given, pelleted according to an original technology, has the following chemical composition on a DM basis: 87.0% organic matter, 37.1% crude protein, 11.7% crude fat, 2.6% crude fiber, 35.6% nitrogen-free extractives and 13.0 per cent ash. Young minks had a feed intake, in relation to body weight, warying from 11.6 g to 58.6 g DM/d. Maximum feed intake related to kg0.75 was recorded at 700 g body weight (approximately 98 g DM/kg0.65). Digestibility of the given food expressed in DE, averaged 87.7 +/- 1.2%, while metabolizability, 82.3 +/- 1.1%. Total heat production related to the intaked gross energy, was 48.0 +/- 3.0%, and the retained energy, 34.3 +/- 4.0 per cent. The net efficiency of the metabolizable energy used for maintenance and production could not be accurately determined. However, taking to account the calculated values required for maintenance, of 649 kJ/kg0.75 in 300 to 600 g young minks, and of 607 kJ/kg0.75 in 600 to 1100 g young minks and also the maintenance efficiency, Km = 0.75, the coefficient for ME utilisation in protein and fat synthesis, of 0.50 and 0.75, respectively, it was able to determine the average ME efficiency used as net energy for maintenance and production: 70%. The highest values of nictemeral metabolism were recorded in the evening, and the lowest ones, at noon; the difference between the maximal and the minimal value did not exceed 6 per cent.

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)

[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.

Effects of excessive dietary zinc on the intrauterine and postnatal development of mink

Dietary exposure to 1000 ppm of supplemental Zn did not result in grossly observable Zn toxicity or Zn-induced Cu deficiency in adult mink. These same concentrations did, however, produce achromatrichia, alopecia, lymphopenia and a reduced rate of growth in the offspring produced by the Zn-treated females. These mink kits also exhibited profound immunosuppression. The in vitro blastogenic response of peripheral blood lymphocytes to concanavalin A was significantly (P less than 0.001) lower in kits born to Zn-treated dams than the response of those born to control dams. The depressed immunoresponsiveness was not a permanent defect since a normal lymphocyte response was seen approximately 14 weeks after weaning and being placed on an unsupplemented basal diet. The impaired lymphocyte reactivity is believed to be the result of altered DNA synthesis in these cells and/or an inhibition of macrophage functions necessary for normal response to the mitogen concanavalin A.

Biological and induction effects of phenobarbital and 3-methylcholanthrene in mink (Mustela vison)

Mink were injected (ip) daily with 20 mg/kg of 3-methylcholanthrene (MC) or 40 mg/kg of phenobarbital (PB) for 3 days and killed 48 hr after the last injection. The duration of anesthetic action of PB increased after each injection. MC-treated mink became anorexic and lost substantial body weight. PB caused enlargement of liver and lungs, whereas MC caused liver atrophy. No major treatment-related morphologic changes including amount of endoplasmic reticulum (ER) in liver were revealed by electron microscopic examination. Microsomal protein content was not increased and NADPH cytochrome P-450 reductase was not induced in liver by either PB or MC. Cytochrome P-450 (448) was increased 3.2-fold by PB and 2.5-fold by MC. Cytochrome b5 was increased 2.3-fold by MC but was not affected by PB. Aminopyrine N-demethylase was enhanced 5.1-fold in activity by PB whereas hexobarbital hydroxylase was not induced. MC-treatment moderately increased the activities of benzo(a)pyrene hydroxylase (1.7-fold) and ethoxyresorufin O-deethylase (2.1-fold) but had no effect on ethoxycoumarin O-deethylase. The most distinctive features of the mink revealed by this study are a) lack of PB induction of the ER, microsomal protein content, NADPH-cytochrome P-450 reductase, and hexobarbital hydroxylase, and b) lack of MC induction of cytochrome P-448-associated mixed function oxidases that are known to be highly responsive to MC in other species.

Prolactin binding sites in the uterus of the mink

The present study was conducted to determine if specific binding sites for prolactin (PRL) are present in the uterus of the mink. Uteri of anestrous mink were homogenized and subjected to differential centrifugation into three particulate fractions, 1500, 15 000 and 50 000 X g. Binding of [125I]oPRL to membranes in an aliquot (200-400 micrograms protein) of the 50 000 X g particulate fraction was quantified. Time and temperature for optimal binding were 18 h at 25 degrees C. Scatchard plot analysis revealed a single set of binding sites for PRL with a Kd of 8.25 X 10(-11) +/- 0.68 M. The maximum amount of [125I]oPRL bound was 28 fmoles/mg protein. Prolactin binding sites were detected in both the uterus and kidney of mink, but not in skeletal muscle, spleen, diaphragm or lung. These data indicate that uterine cell membranes of the mink contain sites that bind prolactin with high affinity.

Feeding Great Lakes fish to mink: effects on mink and accumulation and elimination of PCBS by mink

The effects of feeding Great Lakes fish or fish products (carp, sucker, perch scraps, whitefish racks, and alewife fishmeal) to mink were studied. Growth and furring of mink were normal for all species of fish tested. However, mink fed carp failed to reproduce, and the reproductive performance and/or kit survival in groups fed the perch, whitefish, and sucker were inferior to the control. Only the alewife fishmeal diet supported reproduction and kit survival comparable to the control. PCB residues (as Aroclor 1254) accumulated in mink subcutaneous body fat to as much as 38 times the dietary level, while some individual congeners accumulated up to 200 times. The half-life of PCB in mink adipose tissue was determined to be 98 d. The toxicity of PCBs derived from Great Lakes fish was greater than that observed in previous studies with mink fed comparable levels of technical-grade PCBs.

Urate nephrolithiasis in ranch mink

Urate nephrolithiasis with epistaxis and bleeding around foot pads was diagnosed in ranch mink. Investigation of affected, unaffected-related, and unaffected-unrelated mink did not disclose the cause of these problems but did eliminate inherited bleeding disorders as a cause of the bleeding. All affected mink were males, had been sired by related sires, and were affected in the 1st year of life. Elimination of affected mink and their parents from the breeding stock eliminated the condition from the herd. The findings were consistent with an inherited defect in uric acid metabolism or excretion.

Organochlorines in wild mink (Mustela vison) from Norway

Levels of PCBs, DDE, and HCB have been determined in wild mink caught in the Norwegian counties of Sogn and Fjordane, Rogaland, and Hedmark. No significant differences were founds in organochlorine levels in wild mink from these counties, and the average level, based on fat weight, in abdominal adipose tissue was about 1 ppm DDE, 0.1 ppm HCB and for PCB ranging from 1 to 15 ppm.

[Chemical diagnosis of sodium chloride poisoning in thoroughbred fur-bearing animals (foxes, coypu) and in turkeys and pheasants]

For laboratory diagnosis of sodium chloride poisoning, the concentration of chlorides was polarographically determined in the liver of minks (seven-month-old and older), polar and silver foxes (eight-month-old and older), coypus (nine to ten month old), turkeys (three-month-old), and pheasants. The physiological concentration of sodium chloride in the liver of mink (n = 32) is 2.47 to 3.64 g kg-1, polar foxes (n = 30) 2.46 to 4.23 g kg-1, silver foxes (n =3) 3.27 to 3.44 g kg-1, coypu (n = 23) 1.79 to 3.05 g kg-1, turkeys (n = 30) 1.0 to 2.1 g kg-1, and pheasants (n = 28) 0.95 to 2.37 g kg-1. The exposure of the organism of a pheasant to single lethal doses of common salt (3.4 and 5 g NaCl per kg 1. w.) resulted in a 2.5- to 6-fold increase of salt concentration in liver, as compared with physiological concentration. A decreased concentration of sodium chloride (lower than the physiological standard) was found in the liver of deceased lactating minks.

Control of luteal function and implantation in the mink by prolactin

Mink (Mustela vison) were treated during the period of embryonic diapause with prolactin or ergocryptine (CB-154). Prolactin advanced implantation time and hastened onset of luteal phase progesterone secretion. Duration of gestation in prolactin-treated adult mink was shorter than that of control mink. Ergocryptine had the opposite effects, prolonging gestation and inhibiting onset of luteal phase progesterone secretion. Prolactin is suggested to be the luteotrophin necessary for termination of embryonic diapause in mink.