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Data on immuno- and biochemical identification, genetic control and phylogenesis of new allotype Lpm13 of the Lpm system in domestic mink are presented. This allotype is encountered in mink populations with the frequency 0.9 and higher. The availability of Lpm13 genetic marker permitted another haplotype to be revealed, in addition to the eight known Lpm haplotypes by means of genetic analysis. It was established that, alongside with the earlier described haplotype Lpm3,4,6,8,9,10,11 (abbreviation H3), there exists a similar haplotype, Lpm3,4,6,8,9,10,11,13 (abbreviation H3.13), containing the Lpm13 gene. Of the rest seven haplotypes, five have the Lpm13 gene and two do not. Taking into account this gene and corresponding antigenic marker, the differentiation of 28, instead of 25, phenotypes and 45, instead of 36, genotypes for the Lpm system became possible. Lpm13 antigenic specificity was found with no exception in all individual serum samples taken from ten species and interspecific hybrids of Mustelidae which are closely related to domestic mink. The data obtained give grounds to refer the newly identified Lpm13 gene to the first evolutionary conservative category of genes of the multigenic Lpm system which is also represented by the Lpm6, Lpm9, Lpm10 and Lpm11 genes. The hypotheses of instantaneous formation of polymorphism of the Lpm system in domestic mink are briefly regarded.

An analysis of aneuploidy and polyploidy in bone marrow cells of female minks of different genotype and age has shown that in young minks with unsatisfactory reproductive characteristics, and in old females, the frequency of aneuploid and polyploid cells is significantly higher as compared to that in minks having a good reproductive capacity. The increase in aneuploidy level takes place mainly in the form of hypoploidy, and an increase of the frequency of polyploid cells is accompanied by a parellel increase of the proportion of cells with a low degree of ploidy. A correlation between frequencies of appearance of aneuploid and polyploid cells in minks is observed (r = 0.69 +/- 0.27). On the basis of original and bibliographic data, a hypothesis on a genetically determined instability of karyotype in mutant minks is argumented.

Behavior of progeny of complete diallel crossing between 4 inbred strains of mice (BALB/c, C3H/He, C57BL/6, AKR/J) in a stressful situation was studied. As a model of stressful situation, the open field test was used. A statistically significant influence of genotype on the variability of the behaviour characteristics is found. On the basis of analysis of general combining ability of the strains, a hypothesis is made that in the gene pool of BALB/c and C3H/He strains there are concentrated some genes of additive effect, which increase the strength of emotional reactions of mice in a stressful situation, while in the gene pool of C57BL/6 and AKR/J there are genes of opposite effect. An analysis of the specific combining ability demonstrates that an important role in the control of features characterizing the exploratory activity of mice is played by non-additive gene effects, in particular, the effects of over-dominance. Significant genotypic correlations between the rate of sexual maturation of female mice and their behaviour in stressful situation were observed. The mice which mature earlier are more reactive to the stressing effect of a strange environment.

Seasonal differences in the reaction of the pituitary-adrenal system in domesticated and non-domesticated silver foxes of both sexes to substances activating alpha-, beta-adrenoreceptors, and serotonin receptors were studied. It was shown that the reactivity of the pituitary-adrenal system in silver foxes of either type of behaviour is due, at least partially, to seasonal differences in the state of adrenergic and serotoninergic mechanisms. At the same time, in silver foxes selected for behaviour to man the reaction of the pituitary-adrenal system to the injection of substances activating adrenergic and serotoninergic receptors differs, during the year, from the reaction to these compounds in non-selected animals. The conclusion was made, that in the process of domestication changes take place in the state of serotonin- and noradrenaline mechanisms connected with the regulation of the hypothalamo-pituitary-adrenal complex.

Seasonal changes in the reactivity of adrenal cortex to ACTH and of the pituitary-adrenal system to psychic stress in intact and castrated domesticated (tame) and non-domesticated (non-tame) silver foxes of both sexes were studied. It is demonstrated that in tame foxes there are differences among the intact and castrated animal in their reaction to ACTH and psychic stress. These differences are maifested especially in autumn (September, October) which is the period of extra-seasonal sexual activity for domesticated animals. This points to the fact that the sex glands exert a great influence on the condition of central regulating mechanisms of the pituitary-adrenal complex and that the selection of silver foxes for tame behaviour changes the functional state of these mechanisms through the change of the functional state of the sex glands.

Three new allotypes were discovered in mink sera by means of isoimmunization. Based on the results of identifications, they were referred to the Lpm system of serum alpha2-lipoprotein. They were designated as Lpm 6, Lpm 7 and Lpm 8. The allotyping of serum samples from 342 minks made possible to establish a relation between Lpm 7 and Lpm 8 using the chi2 method; it was also found that these two allotypes related to each of the first five Lpm as well as to their phenotypes, which was described earlier. There was a significant dependence of the expression of Lpm 6 on Lpm 5 indicating a genetic relation between Lpm 6 and other allotypes. The detection of Lpm 6, 7 and 8, which are the most likely under the control of the same gene (or a sustem of genes) as Lpm 1, 2, 3 and 5, is an evidence for the complex structure of the Lpm locus.

The influence of hydrocortisone injections given to males on the penetrance and inheritance of fused gene in mice was studied. The existence of a period sensitive to hydrocortisone action was found. The treatment of males during this interval led to a significant decrease in the proportion of offsprings with fused phenotype. Genetic analysis by means of the closely linked recessive tufted marker permitted to show that the lack of phenotypically fused mice is not due to differential mortality of gametes, zygotes or embryos. The most probable reason for this lack is the decrease in penetrance and partially inherited inactivation of fused gene. Possible mechanisms of the phenomenon found are discussed.

Pre- and post-implantation embryonic mortality and the litter size in intact females and in females stressed during pregnancy were studied. These mice were the progeny of full diallele cross of 4 inbred strains (BALB/c, C3H/He, C57BL/6 and AKR/J). No genetic effects of pre-implantation losses were observed in the control group, but in the stressed group significant genetic effects (both additive and non-additive) on this character were found. Females originating from the most emotionally reactive strain (BALB/c) had a greater value of pre-implantation losses than the other animals, while the progeny of the least emotionally reactive strain (C57BL/6) had a smaller one. The litter size in the latter females was larger than in the former, in spite of the fact that the number of ovulation in RALB/c progeny was higher than that in C57BL/6 progeny. Thus, differential effect of stress on fitness was demonstrated in these experiments.

The effects of mutations on chromosome 17 upon the segregation of the metacentric and acrocentric homologues in the progeny of female mice heterozygous for Robertsonian translocations Rb(8.17) 1Iem and Rb(16.17) 7Bnr were studied. Genetic analysis indicated that the ratio of Rb to non-Rb (normal karyotype) progeny from mothers heterozygous for mutations tf, qk, t12 were not significantly different from 1:1 expected. Introduction of mutations T, Ki, Fu, t6 into the female genotype caused strong distortion of segregation and an increase in the proportion of progeny with normal karyotype (65-70%). From the data on embryonic mortality and cytogenetic observations, it is concluded that distortion of equal transmission arises before MII of meiosis. Consequently, preferential distribution of the metacentric chromosome into the polar body during the first meiotic division is relevant to the segregation distortion observed.

The results obtained by testing 3127 mink sera as well as the analysis of families completely confirmed that the Lpm allotype system of very high density proteins is under genetic control, as postulated earlier. The polymorphism of the first five allotypes is due to the genetic units Lpm1, Lpm4, Lpm1,2, Lpm3,4 and Lpm2,4,5, which behave as Mendelian alleles. The data obtained suggest the existence of an additional gene, LpmX, which, in the homozygous state, determines a very rare phenotype, negative for the first five markers.

The contribution of genetic and environmental components in phenotype variety of corticosteroid adrenal function was studied in undomesticated and domesticated silver foxes during postnatal ontogenesis. The variation of basal and stress plasma corticosteroid level in animals aged 2, 4, 6, 8 months and in vitro secretion of the adrenal gland at the age 8 months was analysed. Significant genotype-depended variability was only demonstrated in undomesticated foxes under stress stimulation conditions. This phenomenon is manifested from the fourth month of life. However, significant genotype-depended variability was already revealed under basal conditions in domesticated foxes, on initial steps of postnatal ontogenesis. The peculiarities of genetic variability of adrenocortical function in foxes selected for domestication are discussed.

The influence of some t-haplotypes on the phenotypic manifestation of fused and kinky genes located on chromosome 17 of the house mouse was studied. It was shown that t12-haplotype decreases the penetrance of these genes to 59-70%. The effect was observed when the Fu gene (or Ki) is transmitted from the females heterozygous for t12-haplotype. This haplotype only affects manifestation of the Fu and Ki genes in the F1.

A genetic analysis of hypertensive reactions under condition of emotional stress in three inbred strains of rats (Wistar, Sprague-Dowly and August) and their F1 reciprocal hybrids is carried out. Highly significant genotypic differences in the arterial pressure level during emotional stress and no genetic diversity in the basal state were found. Application of our own methos to genetic analysis of incomplete diallelic tables for Griffing's experimental design 1 (model 1) showed an existence of significant additive component of genetic variance in autonomic reactivity under the stress. The role of the stress as a factor of differentiation of the genetic structure of population is discussed.

Relative thymus weight was estimated in C3H/He, C57BL/6 mice, their F1 and backcross hybrids, as well as in the progeny of complete diallel crosses between the BALB/c, C3H/He, C57BL/6 and AKR/J strains. On the basis of the analysis of these measurements, a conclusion is drawn that this character is inherited with incomplete dominance of smaller relative weight. The genes determining greater thymus weight are concentrated in the genetic pool of AKR/J and C57BL/6 strains. These genes are characterized by some degree of recessivity with respect to the genes determining smaller thymus weight which are concentrated in the genetic pool of C3H/He and BALB/c strains. The highest concentration of the "plus" and "minus" genes is found in the genetic pools of AKR/J and C3H/He strains respectively.

Population and hybridological analyses have demonstrated that the alloantigenic markers of very high density alpha2-lipoprotein of mink serum, Lpm7 and Lpm8, along with Lpm1, Lpm2, Lpm3, Lpm4, Lpm5, belong to a common immunogenetic system. 21 Lpm-phenotypes are determined at least by 36 genotypes; each of the 11 phenotypes is conditioned by a single genotype, each of the remaining 10 are conditioned by 2, 3 or 4 genotypes. The Lpm allotypes and allogroups are coded by the genetic units Lpm8, Lpm4, Lpm4,8, Lpm4,7, Lpm3,4,8, Lpm1,8, Lpm1,2,7, Lpm2,4,5,7, which behave as alleles. The last, six seem to be haploid sets of closely linked genes.

It was demonstrated that mutations T, Fu, Ki, t6 of chromosome 17 cause preferential transmission of the acrocentric homologues to the progeny from female Rb heterozygotes. The results indicate that the effects of these mutations on segregation are restricted to the Robertsonian translocations involving chromosome 17. Substitution of the parts of chromosome 17 distal or proximal to the T-locus did not alter the effect, of this chromosome on the transmission rate of the homologue. The transmissions effects of these mutations, whether cis or trans with Rb, were the same. It was observed that mothers Rb7/T43H transmitted the chromosome with the reciprocal translocation T43H to 70.9% of their progeny. Data were obtained supporting the idea that structural changes of the chromosomes caused by mutations affect segregation of the homologues in Rb heterozygous females. The possible mechanism of this influence is discussed.

Relative weight of adrenals, thymus, hypophysis and gonads was studied in female mice after 21 days after parturition and in intact males. One group of females was stressed during pregnancy, and another group was intact. All these animals were a progeny of the full diallele cross of 4 inbred mice strains (BALB/c, C3H/He, C57BL/6, AKR/J). On the basis of analysis of general and specific combining ability the conclusion is drawn that the relative weight of the endocrine glands is inherited additively in females of both experimental groups. However, it was found that the size of additive genetic variation for these characters in the population of females, which had been stressed during their pregnancy was larger, than in the control population. A significant role of non-additive genes in the determination of these characters was observed in males. The degree of hypertrophy of adrenals and lysis of thymus in stressed females corresponded to their emotional reactivity. Significant genotypic correlations between the weight of some endocrine glands, on one hand, and the emotional reactivity and the rate of sexual maturation, on the other hand, were found in both experimental groups of females. In the stressed group these correlations were higher.