A. C. Napolitano

Toxicity of 3,4,5,3',4',5'-hexachlorobiphenyl to mink.

Diets supplemented with 0.01 or 0.05 ppm (mg/kg) of 3,4,5,3′,4′,5′-hexachlorobiphenyl (345-HCB) were fed to mink to investigate the toxicological manifestations of this toxic polychlorinated biphenyl congener in a sensitive species. Dietary exposure of mink to 0.05 ppm 3,4,5,3′,4′,5′-hexachlorobiphenyl for 135 days resulted in 50% mortality while no deaths occurred on 0.01 ppm 345-HCB. Clinical signs of toxicity included anorexia, bloody stools, disrupted molting patterns, and thickened, elongated and deformed nails. Ascites and gastric ulcers were present in animals that died. Statistically significant increases in liver, kidney, and adrenal gland weights were found in the 345-HCB-treated mink. Decreases in total and free triiodothyronine concentrations were observed in mink fed the 345-HCB-treated diets and total thyroxine was decreased in the mink fed 0.05 ppm 345-HCB. No consistent histopathologic lesions were found in the thyroid or adrenal glands of the 345-HCB-treated mink, nor were there any statistically significant differences between the 345-HCB-treated and the control mink in serum epidermal growth factor levels, plasma 17β-estradiol and progesterone concentrations, hepatic aminopyrine N-demethylase, and benzo(α)pyrene hydroxylase activities, hypothalamic norepinephrine, dopamine, and serotonin concentrations or in the incorporation of (3H) thymidine by concanavalin-A-stimulated lymphocytes.

Biological effects of epidermal growth factor and 2,3,7,8-tetrachlorodibenzo-p-dioxin on developmental parameters of neonatal Mink

Newborn mink (Mustela vison) kits were administered 0.1 μg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)/kg body weight, 1μg TCDD/kg body weight, 10μg epidermal growth factor (EGF)/ kg body weight, or 50 (μg EGF/kg body weight by intraperitoneal (i.p.) injection (10 ml/kg body weight) for 12 consecutive days to compare the effects of TCDD and EGF on body weight gains, time of eyelid opening, tooth eruption, and pelage development. A 1∶9 acetone-corn oil mixture and 0.85 NaCl served as vehicle controls for the TCDD and EGF groups, respectively. Mortality exceeded 50% at the higher doses of both TCDD and EGF, while at the lower doses, TCDD and EGF resulted in significant reduction of body weight gains. Additionally, EGF caused a significant decrease in the time of eyelid opening and retarded growth and development of the fur of the treated kits. TCDD had no discernible effects on the time of eyelid opening or hair growth. The time of tooth eruption was not significantly affected by either compound.

Environmentally Enriched Male Mink Gain More Copulations than Stereotypic, Barren-Reared Competitors

Wild carnivores in zoos, conservation breeding centres, and farms commonly live in relatively small, unstimulating enclosures. Under these captive conditions, in a range of species including giant pandas, black-footed ferrets, and European mink, male reproductive abilities are often poor. Such problems have long been hypothesized to be caused by these animals housing conditions. We show for the first time that rearing under welfare-improving (i.e., highly valued and stress-reducing) environmental enrichments enhances male carnivores copulatory performance: in mate choice competitions, enriched male American mink (Neovison vison) mated more often than non-enriched males. We screened for several potential mediators of this effect. First was physiological stress and its impact on reproductive physiology; second, stress-mediated changes in morphology and variables related to immunocompetence that could influence male attractiveness; and third, behavioural changes likely to affect social competence, particularly autistic-like excessive routine and repetition (‘perseveration’) as is reflected in the stereotypies common in captive animals. Consistent with physiological stress, excreted steroid metabolites revealed that non-enriched males had higher cortisol levels and lower androgen levels than enriched conspecifics. Their os penises (bacula) also tended to be less developed. Consistent with reduced attractiveness, non-enriched males were lighter, with comparatively small spleens and a trend to greater fluctuating asymmetry. Consistent with impaired social competence, non-enriched males performed more stereotypic behaviour (e.g., pacing) in their home cages. Of all these effects, the only significant predictor of copulation number was stereotypy (a trend suggesting that low bodyweights may also be influential): highly stereotypic males gained the fewest copulations. The neurophysiological changes underlying stereotypy thus handicap males sexually. We hypothesise that such males are abnormally perseverative when interacting with females. Investigating similar problems in other taxa would be worthwhile, since many vertebrates, wild and domestic, live in conditions that cause stereotypic behaviour and/or impair neurological development.

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

Subacute toxicity of dietary heptachlor to mink (Mustela Vison)

Mink were fed diets that contained 0, 12.5, 25, 50, or 100 mg/kg active ingredient heptachlor (as technical grade formulation) for 28 days followed by a 7-day observation period to determine the toxicity of this insecticide to mink. Diets that contained 25 mg/kg, or more, heptachlor resulted in a significant decrease in feed consumption, while 50 mg/kg, or more, heptachlor caused a significant reduction in body weights. Mortality (37.5%) occurred only in the group fed 100 mg/kg heptachlor. The dead mink showed neurological signs of toxicity prior to death. Animals fed 100 mg/kg heptachlor also had reduced relative weights of the spleen and kidney and increased relative weight of the adrenal glands when necropsied at the time of death or at the termination of the study.

Conservation of avian germplasm by xenogeneic transplantation of spermatogonia from sexually mature donors.

Approximately 12.5% of all 9,920 extant bird species in the world are threatened with extinction, and yet conservation efforts through natural breeding of captive species continue to encounter difficulties. However, sperm cryopreservation and artificial insemination offer potential benefits over natural breeding, but their applicability is still limited in nondomestic species. In this study, we aimed to exploit the potential of germ cell xenotransplantation as an alternative tool for preserving germplasm of endangered birds. The study was designed to investigate whether transfer of either spermatogonia-enriched cell fraction (SEF) or crude testicular cell fraction (CTF) from adult Japanese quails (as a model for wild species) would result in recolonization of gamma-irradiated gonads of adult recipient chickens. One month after transplantation, 75% of recipients injected with SEF and 25% of recipients injected with CTF resumed spermatogenesis. However, it took more than 3 months for 33% of the negative controls to resume marginal production of sperm. Some SEF recipients produced more spermatozoa bearing head morphology compared with donor controls. DNA analysis using quail-specific primers did not detect donors DNA in these recipients semen. However, 6 months after xenotransplantation, presence of quail germ cells was demonstrated by polymerase chain reaction and by immunohistochemistry in 1 rooster injected with SEF. These findings indicate that spermatogonia from adult quails were capable of colonizing immunocompetent testis of adult chickens but failed to produce sufficient sperm. Despite this limitation, the present approach represents a potential conservation tool that may be used to rescue germ cells of endangered adult male birds.