Conserved and variable segments of the snake phospholipase A2 amino acid domain]

Homologous amino acid sequences of phospholipases A2 of snakes belonging to families Elapidae, Viperidae and Colubridae were considered in order to study the location of conservative and variable regions. To identify significant conservative and variable regions a comparison between two groups of aligned sequences of snake phospholipases A2 was successfully applied. The phospholipases A2 sequences were divided into two groups (taxons) according to the phylogenetic tree reconstructed from the pair distance matrix. Results of the comparison were plotted to facilitate the identification of significant conservative and variable regions. It was shown, that the results of the comparison between two phylogenetic groups of snake phospholipases A2 didn't depend much on the number of each group representatives, and the location of conservative and variable regions didn't significantly change if one of the groups was represented by the single sequence. It should be mentioned, that the more the phylogenetic difference between groups of phospholipases A2 the more was the number of significant conservative and variable regions. The knowledge of the number and location of conservative and variable regions and their dependence on phylogenetic relations between the compared taxons can be used to predict the synthetic peptide structure to obtain antibodies of various specificity. These antibodies may have either a wide range of cross-reactivity against all of phospholipases A2 or a limited range of cross-reactivity against phospholipases A2 of one taxon.     

Conservative and variable regions of homologous snake phospholipases A2 sequences: Prediction of the taxonspecific peptides structure

Homologous amino acid sequences of phospholipases A₂ (PLA₂) of snakes belonging to the families Elapidae, Viperidae, and Colubridae were considered in order to study the conservative and variable regions location. The PLA₂ sequences were divided into two groups (taxons) according to the phylogenetic tree reconstructed from the pair similarity matrix. Results of the intergroup comparison were plotted to facilitate the identification of significant conservative and variable regions. It was shown that the results of the comparison between two phylogenetic groups of snake PLA₂ did not much depend on the number of each group representatives and did not markedly change if one of the groups was represented by the single sequence. The knowledge of the number and location of conservative and variable regions and their dependence on the phylogenetic relations between compared taxa may be used to predict a synthetic peptide structure to obtain specific antibodies against PLA₂ of one of these taxons. Such prediction is possible if there is a specific region conservative for one taxon but variable for two of them.     

Control of expression of the I factor, a LINE-like transposable element in Drosophila melanogaster.

I factors are LINE-like transposable elements in the genome of Drosophila melanogaster. They normally transpose infrequently but are activated in the germline of female progeny of crosses between males of a strain that contains complete elements, an I or inducer strain and females of a strain that does not, an R or reactive strain. This causes a phenomenon known as I-R hybrid dysgenesis. We have previously shown that the I factor promoter lies between nucleotides 1 and 30. Here we demonstrate that expression of this promoter is regulated by nucleotides 41-186 of the I factor. This sequence can act as an enhancer as it stimulates expression of the hsp7O promoter in ovaries in the absence of heat-shock. Within this region there is a site that is required for promoter activity and that is recognized by a sequence-specific binding protein. We propose that this protein contributes to the enhancer activity of nucleotides 41-186 and that reduced I factor expression in inducer strains is due to titration of this protein or others that interact with it.     

The effect of the size of the irradiation field on the severity and outcome of the radiation injury of swine skin

Swine skin areas of 12.56 cm2, 50 cm2 and 100 cm2 were exposed to beta-particles from 90Sr + 90Y (100 Gy). The increase in size of the exposed site caused a considerable increase in the degree of the affection and a change in the regeneration rate. Epithelialization of 12.56 cm2 skin field was completed by the 14th-16th week, and it was absent after 4.5 years in the fields of 50 and 100 cm2.     

Effects of fibroin microcarriers on inflammation and regeneration of deep skin wounds in mice

The process of tissue regeneration following damage takes place with direct participation of the immune system. The use of biomaterials as scaffolds to facilitate healing of skin wounds is a new and interesting area of regenerative medicine and biomedical research. In many ways, the regenerative potential of biological material is related to its ability to modulate the inflammatory response. At the same time, all foreign materials, once implanted into a living tissue, to varying degree cause an immune reaction. The modern approach to the development of bioengineered structures for applications in regenerative medicine should be directed toward using the properties of the inflammatory response that improve healing, but do not lead to negative chronic manifestations. In this work, we studied the effect of microcarriers comprised of either fibroin or fibroin supplemented with gelatin on the dynamics of the healing, as well as inflammation, during regeneration of deep skin wounds in mice. We found that subcutaneous administration of microcarriers to the wound area resulted in uniform contraction of the wounds in mice in our experimental model, and microcarrier particles induced the infiltration of immune cells. This was associated with increased expression of proinflammatory cytokines TNF, IL-6, IL-1β, and chemokines CXCL1 and CXCL2, which contributed to full functional recovery of the injured area and the absence of fibrosis as compared to the control group.     

Effects of Birth Season and Thymus Transplantation on Experimental Animal Longevity

Biology Bulletin - It is demonstrated in this study that a decrease in the rate of irreversible age-related thymus atrophy affects animal longevity. It was observed that the life span of rats may...