Interplay between aggression, brain monoamines and fur color mutation in the American mink.

Domestication of wild animals alters the aggression towards humans, brain monoamines and coat pigmentation. Our aim is the interplay between aggression, brain monoamines and depigmentation. The Hedlund white mutation in the American mink is an extreme case of depigmentation observed in domesticated animals. The aggressive (-2.06 ± 0.03) and tame (+3.5 ± 0.1) populations of wild-type dark brown color (standard) minks were bred during 17 successive generations for aggressive or tame reaction towards humans, respectively. The Hedlund mutation was transferred to the aggressive and tame backgrounds to generate aggressive (-1.2 ± 0.1) and tame (+3.0 ± 0.2) Hedlund minks. Four groups of 10 males with equal expression of aggressive (-2) or tame (+5) behavior, standard or with the Hedlund mutation, were selected to study biogenic amines in the brain. Decreased levels of noradrenaline in the hypothalamus, but increased concentrations of the serotonin metabolite, 5-hydroxyindoleacetic acid and dopamine metabolite, homovanillic acid, in the striatum were measured in the tame compared with the aggressive standard minks. The Hedlund mutation increased noradrenaline level in the hypothalamus and substantia nigra, serotonin level in the substantia nigra and striatum and decreased dopamine concentration in the hypothalamus and striatum. Significant interaction effects were found between the Hedlund mutation and aggressive behavior on serotonin metabolism in the substantia nigra (P < 0.001), dopamine level in the midbrain (P < 0.01) and its metabolism in the striatum (P < 0.05). These results provide the first experimental evidence of the interplay between aggression, brain monoamines and the Hedlund mutation in the American minks.

[Heterozygosity for Mutations Affecting Coat Pigmentation in the American Mink (Neovison vison) Enhances Structural Stability of Adrenal Cortex under Stress Conditions].

The results of the study of the effects of heterozygosity for mutations affecting coat pigmentation on the response to the environmental stress caused by extreme feeding conditions are provided. The animals with the following genotypes were taken into the study: homozygotes standard (+/+), hedlund white (h/h), and aleutian (a/a) and heterozygotes hedlund white (h/+) and aleutian (a/+). The animals homozygous for the aleutian mutation (a/a) showed a statistically lower growth rate than the animals of other genotypes both in the ontrol and in the experiment (p < 0.05). Under the control conditions, the animals homozygous forboth the wild type standard allele (+/+) and the mutant hedlund white (h/h) and aleutian (a/a) alleles showed the evident tendency for the zona fasciculata and zona reticularis of the adrenal cortex broadening compared to the experimental conditions. At the same time, in the animals heterozygous for the hedlund white (h/+) and the aleutian (a/+) mutations, a clear tendency for increasing size of the zona fasciculata and zona reticularis under the experimental conditions was observed. In the heterozygous animals, although we observed single destructive changes in the adrenal cortex under stress conditions, they were much less profound than in the homozygous ones. This may be related to the broader range of morphological adaptation in the heterozygotes, which gives them the possibility of more significant enlargement of the secreting zone to provide for its adequate functioning.

[Bioactive Effect of the Preparation Biostyl on the Reproductive Function of Different Genotypes of American Mink].

The different role of coat color mutations in the American mink on the per os effect of the biologically active preparation Biostyl was shown. The number of kits per female was the same in all control genotypes, including Standard (+/+ +/+), sapphire (a/a p/p), and lavender (a/a m/m): 4.4 ± 0.4, 4.4 ± 0.5, and 4.3 ± 0.5, respectively. Experimental groups of these genotypes have shown a great contrast among each other: stimulation of the reproductive function was 5.2 ± 0.3 in Standard minks, while suppression of the reproductive function was 3.8 ± 0.6, and 2.3 ± 0.5 in the double recessive mutants sapphire and lavender, respectively. The differentiation in body mass between experimental and control newborn Standard kits was not revealed. A significant decrease in the body mass of newborn experimental sapphire kits as compared to control group in a sex-specific manner was registered.

[Effect of mutations affecting coat color on the blood lymphocyte structure in the American mink (Mustela vison Schreber, 1777)].

American minks with different genotypes containing the Aleutian coat color allele in the homozygous state, including the single recessive Aleutian (a/a); double recessive sapphire (a/a p/p) and lavender (m/m a/a); triple recessive violet (m/m a/a p/p); and dominant-recessive cross sapphire (S/+ a/a p/p), sapphire leopard (S(K)/+ a/a p/p), and shadow sapphire (S(H)/+ a/a p/p) minks, as well as American minks without the Aleutian allele, including the standard (+/+); single recessive silver-blue (p/p) and hedlund-white (h/h); double recessive pearl (k/k p/p), Finnish topaz (t(S)/t(S) b/b); incompletely dominant royal silver (S(R)/+), standard leopard (S(K)/+), and black crystal (C(R)/+); and dominant-recessive snowy topaz (C(R)/+ t(S)/t(S) b/b) and Kujtezhy-spotted (S(K)/+ b/b) minks have been studied. Homozygosity for the a allele has been found to disturb the subcellular structure of leukocyte, namely the formation of abnormally large granules.

[Effects of monorecessive and double recessive mutations affecting coat color on the monoamine content of the brain of the American mink (Mustela vison Schreber, 1777)].

The effects of mutations affecting the coat color on the dopamine, noradrenaline, and serotonin contents of the hypothalamus and brainstem of the American mink have been studied. The sample comprised standard (+/+) and mutant minks, including the monorecessive pastel (b/b), silver-blue (p/p), and white hedlund (h/h) and the combination double recessive sapphire (a/a p/p) and pearl (k/k p/p) ones. The dopamine content of the brainstem of the monorecessive pastel (b/b) and silver-blue (p/p) minks has been found to be higher than in standard (+/+) minks. Conversely, the homozigosity for two coat color loci in double recessive pearl minks (k/k p/p) significantly decreases the noradrenaline and serotonin contents of the hypothalamus. In addition, monorecessive and double recessive minks differ from each other in the serotonin contents of the midbrain and medulla.

[Effect of coat color mutations on behavioral polymorphism in farm populations of american minks (Mustela vison Schreber, 1777) and sables (Martes zibellina Linnaeus, 1758)].

Behavioral polymorphism estimated by the expression of the defensive reaction towards humans has been studied in farm-bred American minks and sables with different color types. Most animals (both minks and sables) from farm populations displayed passive defensive behavior towards humans in the standard hand catch test. Coat color genes have been found to have pleiotropic effects; they influence both the penetrance and expressivity of domestication behavior: in animals with aberrant color types (both sapphire minks and white-and-black sables), the proportion of animals with domestication behavior and the expressivity of this behavior are significantly higher (p <0.01 and p < 0.001, respectively).