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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.

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.

Cytogenetic analysis of the population of the Beskaragai district of the Semipalatinsk oblast adjacent to the territory of the nuclear test site was conducted by means of an ecological genetic questionnaire and cytogenetic examination of metaphase chromosomes. An increase in the total mutation level in the region was observed. The frequency of chromosome aberrations among the population of the Beskaragai district (3.2%) was statistically significantly (about 1.5 times) higher than the background levels in the clear regions (from 1 to 2%). Furthermore, the frequency of aberrations in adolescents was comparable with that in the adults. The spectrum of chromosome aberrations pointed to a significant contribution of radiation component to the mutagenesis.

In samples of wool from 1,229 differently colored newborn Astrakhan lambs, the total content of melanins and the proportion of pheomelanin in the total melanin were studied by the method of electron magnetic resonance spectometry. An analysis of the corresponding computer data base revealed that the distribution of the samples with respect to the proportion of pheomelanin had at least four characteristic maximums; 1-6, 9-10, 28-29, and 39% of pheomelanin. The former two maximums were characteristic for the brown and Karakalpak sur colors, and the latter two maximums, for red-brown kambar color. White hair tips, characteristic for the sur color, and the proportion of pheomelanin were combined almost independently; therefore the possibility is discussed of classifying these characters as independent phenes, and some variants of sur, as their combinations.

A new dominant coat color mutation "talitsa" was revealed in the mink population of "Znamenskii" state fur farm (Tverskaya region', Russia). Qualitative analysis and quantitative assessment of the hair pigment of minks with the standard coat color, Talitsa, Royal-Pastel and American pearl mutations, as well as Talitsa x Royal-Pastel and Talitsa x American Pearl hybrids were conducted. It was shown that hair of all genotypes studied contained only one pigment type, namely, eumelanin. Hair of the standard-colored minks showed the greatest eumelanin content, whereas hair of Talitsa x Royal-Pastel and Talitsa x American Pearl hybrids showed the least content. The morphologic patterns of pigmentation of the mutant minks studied was described, including the shapes, dimensions and color of the pigment granules, as well as their distributions throughout the length and layers of the hair. Talitsa mutation was demonstrated to behave as a strong coloration attenuator in combinations with the Royal-Pastel and American Pearl mutations. It was proposed that the main mechanism determining the phenotypic expression of the Talitsa mutation is the reduction of number of melanocytes in the hair bulbs.

Ultrastructure of cells of the outer root sheath (ORS) of the guard hair follicles from the dorsal part of the body of 12-day old we/we and +/+ mice was studied. Changes observed in the ultrastructure of ORS cells in mutant mice included greater vacuolization of the cytoplasm and damaged structure of mitochondria accompanied by the absence of crisis. Many cells of the ORS outer layer in hair follicles of we/we and +/+ mice showed electron-dense outgrowths oriented axo-proximally which suggests their possible involvement in transportation of the hair, by contraction of these outgrowths, to the skin surface. Possible mechanisms of hair growth in view of these data are discussed.

Qualitative and quantitative analysis of fur pigmentation in brown and black water voles (Arvicola terrestris L.) was performed. Morphology of pigment granules, their distribution along the hair layers and histology of hair bulbs were studied. Morphological data and the results of the analysis of segregation in the progeny, when brown voles were self-crossed and crossed with black ones, led to conclusion that fur colour of water voles is mediated by genes from the agouti series, precisely, black colour is determined by the extreme non-agouti allele (aeae genotype), and in brown voles which are homo- or heterozygous the colour is determined by the agouti allele (AA or Aae genotypes).

117 heads of Ala-Tau breed cattle were studied cytogenetically. The 1/29 translocation was present in 13 animals of unusual for this breed light-grey colour. Chimerism 2n = 59/2n = 60 was found in twins. Dominant mutation transforming dark brown colour to the light-grey seemed to be present in the 1/29 chromosome locus, near the centromere region.

Eighteen hair samples from Karakul newborn lambs with various colors were estimated for eumelanin and pheomelanin contents (Ce and Cp, respectively) by electron spin resonance (ESR) spectrometry and by high-performance liquid chromatography (HPLC). Correlation coefficients between the values estimated by the ESR and HPLC methods were 0.96, 0.93, and 0.99 for Ce, Cp, and Ce/Cp, respectively. The high correlation coefficients show that both methods fit well for estimation of relative values of these parameters. The absolute values of Ce and Ce/Cp coincide rather well when Ce is high, but considerable discrepancies appear when Ce is low. The reasons for these discrepancies are discussed. The HPLC method appears to be more sensitive for detection of low concentrations of pheomelanin, while the ESR method fits well for mass selection purposes.

Histofluorescence technique using glyoxylic acid revealed a specific fluorescence suggesting the presence of biogenic monoamines in early developmental stages of CBA x C57 Black mice. A yellow fluorescence observed in the blastomere surface from the stage of zygote up to that of four blastomere points to the presence of indole derivates. As development proceeds, the fluorescence increases and its colour becomes more and more green, which is characteristic of catecholamines. From the stage of eight blastomeres up to stage of blastocyst specific fluorescence is revealed in the cytoplasm. The inhibitors of monoamine oxidase, introduced into pregnant mice, markedly increased the specific fluorescence. An assumption is made of functional activity of biogenic monoamines in early mouse embryos.

Additional peaks that were known on the esr-spectrograms of red human and reddish-brown Karakul hair to be diagnostic traits of phaeomelanin esr-signal also were found on esr-spectrograms of the tan, but not of black or chocolate brown wool from Icelandic sheep. This tan color is thought to depend on the presence of phaeomelanin and is due to the top dominant allele at the A locus. The two methods of distinguishing between eu- and phaeomelanin-dependent brown colors--esr-spectrometrical and genetical--are in agreement for European as well as for Asiatic breeds. Both light and dark brown Soay fleece samples lacked the additional peaks and are interpreted as eumelanin pigmentation.

The 3H-thymidine labelling has demonstrated that into the internal (accompanying) layer of the outer root sheath (ORS) of the hain follicle the cells incorporate not only in the bulb but above it from the external layers of the ORS. Polymorphism of the ORS cells has been revealed electron microscopically; it can be interpreted as a result of transfer of some motionless, greatly vacuolized, containing a lot of glycogen cells to the cells with electron opaque cytoplasm, radially elongated and moving deep into up to their contact with the internal root sheath. The presence in the external layer of the ORS, at the level of the bulb and above it, some nonlabelled cells even 3 days after 3H-thymidine administration demonstrates against their origin from the cambial cells.

Individual variability of the number and size of silver-staining nucleolar organiser regions (NOR) was studied in 76 pigs of Semirechenskaya, Big White and Duroc breeds. The variability of the NOR number is exclusively caused by the presence of the 8NOR- allele (the chromosomes of the 8th homologous pair lacking the silver-staining NOR). Concentration of the 8NOR- allele is about 0.7 in the average for all three breeds. All 7 offsprings from the homozygous parents male 8NOR- /8NOR- and female 8NOR+/8NOR+ were heterozygotes 8NOR- /8NOR+. These data, together with good agreement between found and expected (according to the Hardy-Weinberg law) frequencies of homo- and heterozygotes suggest the codominant character of the NOR number inheritance. This allows using the NOR analysis to control the parentage announced. The study of inheritance of the size of NOR did not prove unequivocally its codominant character.

Quantitative and qualitative analysis of pigmentation in "singne"-type fur color mutation arising in silver foxes during domestication, was made. It was shown that the decrease in quantity of eumelanine in hair and uneven distribution of pigment granules lengthwise the hair were the reason for formation of "singnes".