[Regeneration of the Skin Pigment System during Larval Development of the Clawed Frog].

We demonstrate regeneration capability of the skin pigment system of clawed frog larvae after local damage to melanophores without skin rupture. The contribution to recovery of pigmentation of the injured area of de novo differentiation of melanophores is compared to contribution of mitotic division of undamaged melanophores localized on the boundaries of the injured area. The regeneration process is observed during various stages of pigment system development of larvae.

Effects of Melatonin on Differentiation Potential of Ito Cells in Mice with Induced Fibrosis of the Liver.

We studied the effects of melatonin on differentiation potential of Ito cells during atypical regeneration of mouse liver under conditions of CCl-induced fibrosis. The dynamics of fibrosis was traced at the histological level and the effects of melatonin on the differentiation potential of mouse Ito cells were evaluated. Melatonin alleviated fibrotic changes in the liver tissue and reduced differentiation of Ito cells into myofibroblasts under conditions of atypical regeneration of the liver in induced fibrosis.

Amino Acid Correction of Regulatory Volume Decrease Evoked by Hypotonic Stress in Mouse Oocytes In Vitro.

Regulatory volume decrease in response to hypotonic stress is typical of the oocytes and early mouse embryos. Changes in the kinetics of osmotic reaction can be used as a marker of the modulating effect of the incubation medium on transmembrane transport in embryonic cells. Quantitative laser scanning microtomography (QLSM) was used to measure oocyte volume.

[Cellular dynamics of the outer layers of the hair follicle of fine-wool sheep during the phase of stable hair growth].

The structure, origin, and migration of outer sheath cells of the hair follicles of domestic sheep were studied by electron microscopic, autoradiographic, and histochemical (glycogen) in order to understand the role of this layer in hair morphogenesis. We demonstrated that the cells of the outer layers of the outer sheath interpose into the inner "companion" layer of the outer sheath. Although this process takes place all along the hair follicle from the lower bulb up to the sebaceous glands orifices, it mainly takes place over the bulb.

[Metabolic syndrome and melatonin].

Metabolic syndrome (MS) is characterized by the following symptoms: obesity, AH, dyslipidemia, insulin resistance. Pathophysiologically, MS is underlain by disorders of many biochemical and physiological processes, such as elevated levels of low density lipoproteins, hyperstimulation of pancreatic b-cells, increased insulin secretion, substitution of lipid metabolism for carbohydrate one, overgrowth of adipose tissue, excess production of adiponectin, leptin and other signal molecules and a rise in their local intravascular concentration, weight gain. Endogenous and exogenous melatonin inhibits these pathophysiological mechanisms, normalizes metabolism, equilibrates insulin secretion, prevents pancreatic hyperfunction, phosphorylates insulin receptors, inactivates active oxygen and nitrogen species including those produced in LDLP metabolism.

Estimation of isotonic point of incubation medium for two-cell mouse embryo.

Osmolarity of Dulbecco's medium at which the volume of two-cell mouse embryo remained similar to that of intact embryo was determined. The method is based on comparison of kinetic curves describing the volume of embryonic cell in solutions of different osmolarity. The blastomere volume was measured by quantitative laser microtomography after fixed osmotic stress intervals.

[Characteristics of the reparative regeneration of fins in the polypterid fish (Polypteridae, Actinopterygii)].

Epimorphic regeneration of fins was studied in different ray-finned fishes (Actinopterygii), but species representing the phylogenetically basal lineages of the taxon have remained outside the attention of researchers. Information on the regenerative abilities of these groups is important both for understanding the evolutionary origins of the epimorphic regeneration phenomenon and for assessing the universality of regenerative potencies in Actinopterygii. Addressing this problem, we studied for the first time fin regeneration in two members of the archaic family Polypteridae: the ropefish (Erpetoichthys calabaricus) and the Senegal bichir (Polypterus senegalus).

[Cyto B dependent and ouabain insensitive regulatory volume decrease in bicellular mouse embryo].

Mouse single-cell embryos exhibit robust Regulatory Volume Decrease (RVD). In what manner the very early mammalian embryo following zygote stage is appreciably altered by the anisotonic extracellular solution is, as yet, totally unclear. Little attention was paid to this direction since there was no way to determine the blastomere volume.

Analysis of changes in cell volume of a mouse early embryo exposed to osmotic shock.

The impact of the osmotic component of the incubation medium for the volume of mouse early embryonic cell was studied by laser scanning microscopy. Common Dulbecco's medium caused a prolonged hyperosmotic effect. Adaptive phase of regulatory compensation for the osmotic shock was observed under hypotonic conditions.

[Melatonin promotes and synchronizes protein synthesis in hepatocyte culture from old rats].

The effect of 1 to 1000 nM melatonin was studied on daily cultures of rat hepatocytes on slides in serum-free medium. The minimum melatonin concentration (1 nM) proved to synchronize protein synthesis in asynchronous sparse cultures of hepatocytes from rats of different age, and a circahoralian rhythm of protein synthesis was revealed in them. In dense weekly synchronous hepatocytes from old rats (2.

[Hereditary muscular dystrophy: bioengineering approaches to muscle fiber repair].

Restoration of disturbed functions of the organs and tissues is the main task of contemporary genetic and cellular biotechnology, including genetic and cellular therapy. Duchenne dystrophy, one of the most widespread human genetic diseases, is at the same time the most extensively studied from the viewpoint of both genetic and histological changes leading to muscle fiber degeneration. Although many studies carried out on models, recognized analogous to Duchenne dystrophy, gave hopeful results, clinical tests with the use of developed methods gave no expected success and the rate of mortality from this disease amounts to 100%.

Transplantation of human embryonic myoblasts and bone marrow stromal cells into skeletal muscle of C57BL/10J-mdx mice.

We studied expression of dystrophin in skeletal muscles of C57BL/10J-mdx mice after transplantation of human embryonic and fetal myoblasts and bone marrow stromal cells. Dystrophin-positive areas corresponding to the location of transplanted cell were detected in muscles of all recipient mice after transplantation of different cell cultures, but the distribution of dystrophin characteristic of normal muscle fibers was detected only after transplantation of embryonic myoblasts. Dystrophin distribution in muscle fibers after transplantation of fetal myoblasts and bone marrow stromal cells was atypical.

[Development of loach eggs after experimental increase of cell mass in the dorsal and ventral areas of blastoderm].

The fertilized loach eggs were injected, before the beginning of cleavage, with the nuclear dye Hoechst 33258 and left to develop until the late blastula stage. Some cells of the dorsal area of stained blastoderm were transplanted in the analogous area of intact embryos of the same age, which led to an earlier and more pronounced development of head and trunk structures in recipients. A relationship was established between specific features of the development of recipients and localization of descendants of the transplanted cells.

[Activity of exogenous genetic designs, introduced into cells by a ballistic transfection method, in murine ontogenesis].

We used the method of particle bombardment (ballistic transfection) to introduce beta-galactosidase and human dystrophin genes into mouse embryos and skeletal muscles of adult mice. We examined the mechanisms of DNA transfer into skeletal muscle cells, the biological processes accompanying and following this transfer, the susceptibility of various types of muscle cells to transfection, and the duration of expression of and conditions affecting the introduced genes. We have also developed an effective, convenient, and practical methods of skeletal muscles transfection.

[Discrete probability of a model for information provision on early embryonic development].

A percolation model of the diffuse redistribution of morphogenetic information in early regulative development is analyzed. It is demonstrated that the statistical average values of cell connectedness remaining below the percolation threshold of the spatial redistribution of developmental determinants do not provide for the formation of cell structures of the necessary size. The average number of cell interactions should exceed the percolation threshold, and, therefore, the carriers of morphogenetic information in early development can move over distances comparable with the size of the entire embryo.

[Distant wave interaction in the early embryogenesis of the loach Misgurnus fossilis L].

Groups of loach (Misgurnus fossilis L.) embryos of different ages were kept in different quartz cuvettes for 20-24 h so that only optic contact between the groups was possible. Subsequent observations showed that parameters of their development deviated from those in the control groups.

[On the 60th anniversary of the Department of Embryology of Moscow State University].

The Department of Embryology of Moscow State University is 60 years old on September 1, 2000. This is not all that old, especially in comparison with the almost 250-year history of the university itself or the 150-year history of embryology in Russia, but it is sufficient, in looking back, to grasp our present situation in the common flow of events and time.

[The effect of chemical mutagens on the chromatin properties of mouse spermatogenic cells].

The main components of chromatin (DNA and protamine-like proteins) were studied in the Dipin- and NMU-treated mouse spermatogenic cells using quantitative cytochemistry. Marked variation of DNA content and deficiency of the basic nuclear proteins have been shown in epididymal spermatozoa developed from cells, which were at the moment of treatment either at the early prophase I or at intermediate stages of spermiogenesis. These stages are, respectively, one of genetically most sensitive stages and a stage of active synthesis of spermiospecific proteins, which play an important role in condensation and stabilization of gamete chromatin.

[The effect of chemical mutagens on mammalian spermatogenesis. A cytogenetic analysis].

It was shown using the micronucleus test and estimating the defects of sperm heads that premeiotic and meiotic mammalian cells are genetically very sensitive to Dipin and nitrosomethylurea. In rats, unlike mice, the stem and differentiating spermatogonia with serious chromosomal defects are not eliminated and pass through a "sieve" of mitotic and meiotic divisions reaching the stage of round spermatids. Our observations suggest long-term preservation Dipin-induced, rather than nitrosomethylurea-induced, mutations in the stem cells of both mice and rats.