Biomedical subjects
Publications and source records attributed to Iu I Rozhkov.
Natural selection in populations of cattle was studied. Heterozygosity level, pure-blooded proportion, stabilizing selection, and directional selection II acted as quantitative traits. Changes in the proportion of pure bloods with time were found, something not taken into account in breeding practice.
Modifications of similar type were noted in the number of multiple AMY-1 forms of amylase isozyme for various species of Artiodactyla. It is supposed that these modifications are linked to periodical activation during evolution of genes responsible for modification of the molecules. Data obtained on Bovinae hybrids testify to this point of view. Inactivation of active and reinactivation of "silent" genes responsible for modification of AMY-1 molecules are observed in hybrids of bison x cow and bison x aurochs combinations.
Dynamics of allele frequencies for the B-locus of blood groups in cattle populations and of a number of phenotype indexes in these animals was studied. It is determined that natural stabilizing selection and prezygotic selection, leading to a change in genetic structure, act in every population. The role of sires' influence on this process is insignificant.
Variability of transferrins in Bovinae is controlled by two loci: Tf (the locus of structural transferrin gene) and T (the locus of a gene responsible for protein modification). Originally, the ancestors of Bovinae, like the other ruminants, had the R type of transferrin (T-/T- genotype, inactive T gene). Later on, the T gene activation occurred and the B type appeared (T+/T-, T+/T+ genotypes). The subsequent evolution of Bovinae was accompanied by almost complete fixation of T+ allele. In one of the Bovinae representatives (Bos taurus L.) the frequency of T- allele remained at the level of approx 0.1. A hypothesis is proposed which explains the change of the transferrin type in Bovinae by imitation of multiple allelic forms of this protein present in Tf heterozygotes, by supplementary modificatory multiple transferrin forms arising on activation of the minor gene (T+). This process is assumed to involve the reduction of Tf locus variability. Since this hypothesis proceeds from the assumption of TF heterozygote advantage, the question is considered, whether this assumption is compatible with high polymorphism of Tf locus which significantly exceeds that for other loci.
Three different types of isoenzymes, Am1, Am2 and Am3 have been revealed by polyacrylamide gel electrophoresis (PAG) and affine PAG electrophoresis in artiodactyla. In cattle and pigs Am2 isoenzyme is monomorphic, as shown by PAG electrophoresis, and polymorphic in affine gel separation (two alloenzymes, Am2A and Am2B have been revealed). Some of sheep have no Am2 isoenzyme, which, apparently, account for the presence of minus-allele. Am2 isoenzyme was not detected in Saiga tatarica which are related to sheep. In reindeer, Am2 system is monomorphic, Am3 system is polymorphic, in reindeers, Saiga tatarica and pigs the variability of the latter system being determined by A3A, A3B alleles.
Genetically conditioned polymorphism of alpha-amylases in musk ducks, domestic ones and their hybrids has been described. Two isoenzymes (AMY-1, AMY-2) are in blood serum of the ducks. One of them is apparently formed in crope gland and other--in pancreas. AMY-2 is monomorphic in both species. AMY-2 is polymorphic with three alleles (Amy-1A, Amy-1B, Amy-1B) in musk ducks and monomorphic in domestic ducks (Amy-1C). The hybrids have also allele obtained by them from domestic ducks.
60 patients, aged 28 to 80 years, hospitalized for surgical treatment of various esophageal, gastric and intestinal diseases have been examined. In 30 patients (group 1) during surgery conventional neuroleptanalgesia was accompanied by intravenous low-intensity laser blood irradiation (ILILBI). The remaining 30 patients formed the control group. Unlike control patients, in patients of group 1 adequate perfusion and tissue oxygenation were maintained throughout the whole period of surgical intervention, general stress reaction to surgical trauma was less pronounced. The data obtained demonstrate the advisability of ILILBI introduction into a complex of anesthesiological protection.
A stabilizing selection which is made in cattle according to phenotypic characters affects simultaneously a genetic character--the level of individual heterozygosity++. As a result animals with mean (modal) level of heterozygosity++ have the least probability of elimination. Similarly, the driving selection in pigs and horses leads to a change in both phenotypic characters and genetic character, the level of individual heterozygosity++. In this case the most heterozygous animals have the least probability of elimination.
Genotypes of B-locus of blood groups in cattle have been studied for peculiarities of their formation. Studies of different populations have shown that some parental alleles have an advantage during formation of the descendant genotype for the above mentioned locus.
The general "plan" of animal structure evolves due to the changes both, in body proportions and body size. The method allowing to estimate the level of population differentiation according to these two parameters was considered. In the process of population differentiation two phases of form formation can be discerned. On the first stage of microevolution the morphogenesis mainly proceeds by proportion changes. The next stage is characterised primarily by changes of size. The same phase can be observed at intra-population level. The selection directed to the increase in differentiation of individuals according to their proportions.