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Biomedical subjects

L N Trut

Publications and source records attributed to L N Trut.

At least 19 recordsLinked to original sources
PubMed2006

[The effect of methyl-containing supplements during pregnancy on the phenotypic modification of offspring hair color in rats].

The effect of methyl supplements to the diet of pregnant homozygous (AAHH) female rats with agouti coat color mated with homozygous (aahh) males on the phenotypic modification of the coat color of their heterozygous offspring (AaHh) has been studied. Comparative morphological analysis of the main parameters of hair that determine coat color, including the total length of hairs of different types and the length of the upper black (eumelanin) and light (pheomelanin) parts of awn hairs has been performed. The pattern of pigment granule distribution among hair layers has been analyzed. The melanin content of the hair has been determined using electron spin resonance (ESR). Although all offspring have a typical agouti coat color (alternating black and light portions of hair), 39% of them have a darker coat color than control and other experimental rats have. The main differences between the offspring with darkened and standard coat colors are accounted for by the ratio between the eumelanin and pheomelanin portions of awn hairs. In darkened offspring, this ratio is significantly higher than in control rats. The possible mechanisms of the phenotypic modification of agouti coat color in experimental animals are discussed.

Agouti Signaling Protein↗
PubMed2004

Effect of selection for behavior on pituitary-adrenal axis and proopiomelanocortin gene expression in silver foxes (Vulpes vulpes).

Silver foxes from a commercial population (farm bred or unselected for behavior control) and from populations selected for tame behavior and enhanced aggressiveness towards man have been investigated. Plasma cortisol and adrenocorticotropic hormone (ACTH) levels, pituitary ACTH levels, POMC gene expression in the anterior pituitary, and corticotropin-releasing factor (CRF) gene expression in the hypothalamus were assessed. The results indicate that the males from the tame-behavior group have lower plasma cortisol and ACTH levels and POMC gene expression in the anterior pituitary in response to capture and handling in comparison with unselected ones. Foxes from the aggressive behavior group also have lower POMC expression, although plasma cortisol and ACTH levels remain the same as in unselected ones. The three groups of animals show no significant changes in the ACTH level in the pituitary and CRF expression in the hypothalamus.

Adrenocorticotropic Hormone↗
PubMed2004

[An experiment on fox domestication and debatable issues of evolution of the dog].

This paper is a review of the results of the authors obtained in a long-term experiment on fox domestication. Debatable issues of dog evolution are discussed in light of these results. It is demonstrated that genetic physiological mechanisms of the behavior transformation during selection and the nature of the arising phenotypic changes are associated with retarded development of corresponding ontogenetic processes. As a result of this retardation, the adult animals retain juvenile traits of behavior and morphology (the phenomenon of neoteny). The role of hormonal changes caused by domestication in the evolutionary origin of neoteny is discussed.

Animals↗
PubMed2003

[Pleiotropic effect of the hooded mutation of the rat on male fertility].

Several reproductive parameters were studied in males homozygous (hh) or heterozygous (Hh) for the hooded mutation as compared with completely pigmented wild-type males (HH). Histological analysis of the testes was carried out in males of the three genotypes. The proportion of sterile males in homogeneous matings of homozygotes hh was twice as high as in matings of heterozygotes. The proportion of sterile males in matings yielding no progeny was also twice higher in homozygotes hh as compared with heterozygotes. No sterile males were detected in matings of completely pigmented wild-type animals. Unilateral cryptorchidism, a hypoplastic testis combined with a hyperplastic one, or hypoplasia of both testes were observed in some males homozygous for the hooded mutation. Morphologically, these defects were associated with underdevelopment or the complete absence of spermatogenic epithelium or with the presence of gaps and cells with large nondivided nuclei in the epithelium. The results showed that the hooded coat-color mutation exerts a pleiotropic effect on male fertility in rat.

Animals↗
PubMed2002

Directional left-sided asymmetry of adrenals in experimentally domesticated animals.

Directional left-sided asymmetry of the adrenals was typical of black and silver foxes, American minks, and gray rats selected by their behavior. In domesticated, but to a greater extent, in aggressive animals, the weight of the left adrenal and the width of its medulla and cortex markedly surpassed the corresponding parameters of the right adrenal. In aggressive animals enlargement of the left adrenal cortex was associated with widening of the zona reticularis, while in domesticated animals with enlargement of the zona fasciculata.

Adrenal Cortex↗
PubMed2002

[Morphology of hair pigmentation in wild red foxes, silver foxes, and their hybrids].

The effects of dominant allele Ar of locus Agouti on the morphology of hair pigmentation were described in foxes. The Ar allele was shown to determine the type of melanin and its content in hair with no effect on the morphology of pigment granules and their distribution throughout a hair. Using the method of electron spin resonance (ESR), the types of melanin (eumelanin and pheomelanin) and their content in the hair of red (ArArEE) and silver (aaEE) foxes and their hybrids (AraEE) were determined. In silver foxes, only one type of melanin (eumelanin) was found. In red foxes and their hybrids (which are phenotypically similar but darker than red foxes), both types of melanin (eu- and pheomelanin) were found. The highest melanin content was detected in the coat of silver foxes. In the hybrids, the total melanin content was lower than in silver foxes, but significantly higher than in red foxes. In red foxes, the contribution of pheomelanin to the total hair melanin content was twice as large as in the hybrids.

Animals↗
PubMed2000

[Mutations hooded and nonagouti in the gray rat (Rattus norvegicus): effect of selection on behavior and photoperiod].

Selection of wild Norway rats for behavior conducted in different directions was shown to affect the rate of appearance of coat-color mutants. In the population selected for domestication (reduced aggressive-fearful behavior toward humans), almost all animals acquired the semirecessive mutation hooded (h). Selection for aggressiveness (enhanced aggressive-fearful response) was accompanied by an increase in the frequency of homozygotes for a recessive mutation nonagouti (a). In the population selected for aggressive behavior, seasonal variation in the rate of appearance of mutant animals was observed. Experiments on the maintenance of nonselected rats under artificial short-day conditions showed possible interaction between alleles Agouti (A) and nonagouti but exclusively in heterozygotes for hooded. This interaction may lead to the inactivation of the normal A allele in some AaHh heterozygotes and their transformation into aa homozygotes, which would resemble paramutation. Discussion of the results is focused on several issues: recent evidence on coat-color genes and their function, directional (as opposed to random) nature of appearing mutations, and the possibility of meiotic inheritance of genetic changes occurring in early development.

Animals↗
PubMed2000

[Interhemisphere neurochemical differences in the brain of silver foxes selected for behavior and the problem of directed asymmetry].

The study deals with the mechanisms that bring about a directional asymmetry in the expression of some morphological traits observed in some animals subjected to experimental domestication. The key role in the integration of development is attributed to the genetic systems controlling the activity of brain neurotransmitter systems. Therefore, the investigation of directional asymmetry of morphological traits began with the analysis of interhemispheral differences in neurotransmitter activity in animal lines selected for domestic and aggressive behavior. Experiments on silver foxes reveal interhemispheral differences in the dopaminergic system emerging in the striatum. An increased dopamine level is observed in the right half of the striatum of aggressive foxes and in both right and left halves of the striata of domestic foxes. On the basis of the literature data, it is suggested that the considerable increase in the dopamine level in the right halves of the striata of both aggressive and domestic animals is related to a genetic increase in the manifestation of emotional response in both lines, whereas its increase in the left half of the striatum of domesticated foxes may be related to a correlated deterioration of the function of the pituitary-adrenal system.

Animals↗
PubMed1997

[Effect of domestication of the silver fox on the main enzymes of serotonin metabolism and serotonin receptors].

In silver foxes significant alterations in the activities of basic enzymes of neurotransmitter serotonin metabolism as well as in the densities of receptors caused by selection for the absence of the aggressive defensive reaction to man were demonstrated. In the midbrain and hypothalamus of animals selected for the absence of aggressive behavior, the activity of tryptophan hydroxylase, the key enzyme of serotonin biosynthesis, was found to be remarkably higher than in animals selected for highly aggressive behavior. Domesticated animals were characterized by low activity of the main enzyme of serotonin catabolism, monoamine oxidase type A, increased Michaelis constant km, and an unchanged maximum reaction rate (Vmax). No changes in the specific binding of [3H]-ketanserin and [3H]-8-OH-DPAT in the frontal cortex of domesticated foxes were revealed; however, in the hypothalamus, the low values of Bmax for the [3H]-8-OH-DPAT specific binding were observed, indicating the decreased density of the 5-HT1A receptors. It is assumed that the transformation of a wild aggressive animal into a domesticated one taking place during directional selection is caused by hereditary alterations favored by artificial selection in the activity of the main enzymes of serotonin metabolism and serotonin receptors.

Aggression↗
PubMed1997

[D.K. Beliaev's evolutionary concept--ten years later].

D.K. Belyaev's evolutionary concept is considered in terms of (1) experimental results obtained during studies on domestication mainly in recent years and (2) modern views on evolution under extreme conditions and the role of the hierarchic system of regulation of genetic expression in evolution. Changes in neuroendocrine regulation in the course of long-term domestication are characterized, and the morphogenetic role of hormones and neurotransmitters is discussed. The effects of selection on the rate of some developmental processes and the importance of the resultant heterochronias for the morphogenetic consequences of selection for behavior are described.

Animals↗
PubMed1997

[The hooded allele and selection of wild Norway rats Rattus norvegicus for behavior].

Selection of wild gray rats for domestication (tame behavior) resulted in a sharp increase in the frequency of heterozygotes at the h allele of hooded, the main locus of rat depigmentation. The observed effect of the selection on the manifestation of the h allele is compared with similar effects giving rise to piebaldness in other animals subjected to experimental domestication. The results are discussed in terms of genetic specificity of piebaldness and of the selection vector.

Alleles↗
PubMed1993

[Is selection an alternative or complementary to variation].

This paper reviews the data demonstrating a large magnitude of variability during long-term selection. The attention has been focused on the studies revealing preservation of genetic variability under conditions of intensive selection force. The data are discussed in terms of both classical genetic mechanisms to preserve variability and possible influence of selection on frequency of de novo arising changes. It is supposed that the selection vector and the rate at which the changes occur are interrelated. If selection acts mainly on phenotypes controlled by polygenes with regulatory functions, then its effect on variability is the highest. It is underlined that behavioral and physiological traits represent the phenotypes of such type.

Animals↗
PubMed1993

[Comparative analysis of the level of heterozygosity for glucose phosphate isomerase (GPI) locus in silver foxes (Vulpes vulpes) of domesticated and control populations].

This communication is the first step of the studies on the correlation between protein polymorphism and the level of phenotypic diversity. The level of heterozygosity for glucose phosphate isomerase (GPI) locus was analysed in two populations of silver foxes. One of them has been selected for domestic behaviour during many years. This selection vector gave rise to many phenotypic novelties; 46% of the foxes analyzed has aberrant phenotypes. Another population was control bred under the same conditions of experimental farm of Siberian Dept. Russian Sci. with a commercial purpose. All the foxes analyzed from this population, except one, had a standard phenotype. Among 96 domestic foxes under analysis, only one heterozygotes for the GPI locus was detected. Among 112 control foxes, six were heterozygotes. In other words the data obtained indicate no correlation between the level of morphological diversity and the state of heterozygosity of the GPI locus.

Animals↗
PubMed1991

[Component analysis of craniologic characters of silver foxes (Vulpes fulvus Desm.) and their changes arising under domestication].

The data on cranial measurements performed in silver foxes indicate that there are differences in sizes measured between the farm foxes--bred population and the population selected for domestication. A method of principal components was used to analyse the cranial measurements and their changes under domestication. The first component covers about 50% of cranial diversity, which is interpreted as variation in the total skull size. This component clearly separates the two sexes, but not different populations. The second component presumably reflects the growth rate allometry between the skull length and width. The third and fourth components are measurements of skull width; the fifth one reflects the sizes of brain skull. None of these components clearly separate the foxes from farm--bred and domesticated populations. However, some differences in distribution are observed.

Animals↗
PubMed1991

[Intracranial allometry and craniologic changes during domestication of silver foxes].

Skull proportions and pattern of intracranial allometry in farm foxes of bred domesticated populations are compared. Changes in skull measurements and bivariate allometry are observed in domesticated males, which in this respect become closer to domesticated females. The changes in the allometry pattern in the domesticated population points to deep modifications of regulatory ontogenetic processes which underlie the allometric growth. However, morphological changes in domesticated foxes cannot be only accounted for by allometry.

Animals↗
PubMed1990

[The use of the method of principal components for phenogenetic analysis of the integral domestication trait].

In the course of long-term experiment on domestication of silver fox, it was necessary to determine the most important behavioral features, selection for which would give domestication effect. The mathematical method of principal components was used for the analysis of 20 fox behavior traits. The combination of the initial traits which reflected the structure of the integral trait, i.e. domesticated type of behavior, was determined. The practical use of this combination seems to more adequately estimate the level of domestication of a given animal, which is indispensable for subsequent effective selection.

Animals↗