[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. We establish that, compared to ontogenetic dynamics, pigmentation development in animals is more intense during the regeneration.

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 CCl4-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. The hepatoprotective role of melatonin was shown.

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. In this paper, it is shown that addition of 5 µM glycine, taurine, or GABA, as well as ATP to Dulbecco's medium abolished the regulatory volume decrease in mature mouse oocytes.

[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. Labeled cells interposed into the companion layer move towards sebaceous glands orifices more than 24 hours faster than labeled cells of the inner sheath and hair, because these cells included the label not in the bulb cambium (as hair and inner sheath) but over the bulb, and from this point they start movement. Interposition of cells into the companion layer must cause increase of its volume and additional volume supposed to be led away into the pillar canal around the hair near the sebaceous glands orifices. This can provide the mechanism for the propagation of the hair and inner sheath promotion to sebaceous gland orifices.

[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. Melatonin has specific MT1 and MT2 receptors localized in all body cells. Due to this, it exerts combined preventive action in patients with MS. Recently, melatonin has been reported to have therapeutic effect in MS; it may be recommended to treat this condition.

[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). Along with the ability to regenerate the bony rays of fins, widespread among Actinopterygii, polypterids show the ability to effectively regenerate the endoskeleton and musculature of their fins. This unusual feature allows us to suggest polypterids as new model organisms for the study of the mechanisms of vertebrate limb regeneration.

[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. This work has served to quantitatively investigate the osmotic response of bicellular mouse embryos employing Laser Scanning Microtomography (LSM) followed with three-dimensional reconstruction (3 DR). We have shown that bicellular mouse embryos in hypotonic Dulbecco's experience RVD. Embryonic cells subjected to hyposmolar exhibit rapid osmotic swelling followed by gradual shrinking back toward their original volume. The van't Hoff law defines swelling phase with the effective hydraulic conductivity of 0.3 micron x min(-1) x atm(-1). Water release during RVD in bicellular mouse embryos is abolished by Cytochalasin B (Cyto B) and the volume recovery is insensitive to ouabain treatment.

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. It was found that Dulbecco's saline with 125 mM NaCl solution is an isotonic solution for two-cell mouse embryo. This concentration corresponds to 290 mOsm, which is lower than osmolarity (~310 mOsm) of media routinely used for culturing of differentiated cells or biological fluids, e.g. blood plasma.

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. From these data, water permeability of the blastomer membrane is evaluated as 0.4 micro/(minxatm).

[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 (2.5-years-old with the weight of about 600 g), melatonin improved cell synchronization to the level of young animals. Melatonin treatment increased the mean rate of protein synthesis in rats of different age.

[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%. Based on the world experience and analysis of the authors' data, possible influence of the intensity of regeneration on success of genetic and cellular therapy has been considered.

[Use of high velocity mechanical injection for the transfer of foreign DNA into early mouse embryos]. / Ispol'zovanie vysokoskorostnoi mekhanicheskoi in"ektsii dlia perenosa chuzherodnoi DNK v rannie émbriony myshei.

The possibility of high velocity mechanical transfer of foreign DNA into inner cell mass of mouse blastocyst was shown. Penetration of tungsten microparticles into early embryo cell nuclei and their localization on mitotic chromosomes was demonstrated. About 70% of developing embryos survived the bombardment. Total DNA of the mice born from bombarded embryos was analyzed by blot-hybridization and PCR with Southern hybridization. In three cases, the presence of the transferred plasmid DNA (pSV3-neo) was revealed.

[On the 60th anniversary of the Department of Embryology of Moscow State University]. / K 60-letiiu kafedry émbrriologii Moskovskogo gosudarstvennogo universiteta.

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.

[Pigment migration in the dermal melanophores of amphibian larvae in the interphase and during mitosis]. / Peremeshchenie pigmenta v dermal'nykh melanoforakh lichinok amfibii v interfaze i vo vremia mitoza.

Functioning of the dermal melanophores was studied in the isolated skin of the Rana temporaria and R. esculenta tadpoles at stages 17-21 and 20-24 (after Kopsch). At all stages we studied melanophores exhibited reaction to light. From stage 18 on repeated alternation of pigment dispersion and aggregation was obtained using melanotropins and melatonin. When observing transition of the melanophores from interphase to mitosis, it was found that dividing dermal melanophores could be distinguished due to changes in their appearance shortly before the end of prophase.

[Discrete probability of a model for information provision on early embryonic development]. / Diskretnaia veroiatnostaia model' informatsionnogo obespecheniia rannego émbrional'nogo razvitiia.

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. The assumption concerning the percolation mechanism of cell death is used as a basis for estimating the statistical average value of cell connectedness at which the predicted number of cells theoretically isolated from the flow of signal molecules corresponds to the observed frequencies of dying embryonic cells. The estimated average number of cell interactions significantly exceeds the threshold of information resource percolation in the embryonic space and agrees with estimations of other authors, based on direct observations. The probable role of the diffusion front, or percolation cluster shell, in the regionalization of embryonic structures differing in their prospective values is discussed. It is shown that the duration of the communicative period, along with the statistical average number of channels providing for the intercellular transfer of signal molecules by diffusion, is a parameter controlling the processes of determination of embryonic structures.

[Development of loach eggs after experimental increase of cell mass in the dorsal and ventral areas of blastoderm]. / Razvitie ikrinok v'iuna posle éksperimental'nogo uvelicheniia kletochnoi massy dorsal'noi i ventral'noi oblastei blastodermy.

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. Transplantation of cells of the dorsal area of stained blastoderm in the ventral area of embryos of the same age led to the formation of two axial complexes, both at the same level of development, nut behind the control, and stained cells were located predominantly in one of twin embryos.

[Distant wave interaction in the early embryogenesis of the loach Misgurnus fossilis L]. / Distantnye volnovye vzaimodeistviia v rannem émbriogeneze v'iuna 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. Wave-mediated biocorrection proved to have both positive and negative effects, depending on the developmental stages of the interacting groups. Changes in spectral characteristics and polarization of biological radiation affected the results of the experiments. Various developmental abnormalities caused by distant wave-mediated interactions of embryos and specific to each combination of developmental stages and conditions of optic communication are described.

[Dynamics of the redistribution of pigment granules in the dermal melanophores of anuran amphibians. 1. Dispersion]. / Dinamika pereraspredeleniia pigmentnykh granul v dermal'nykh melanoforakh beskhvostykh amfibii. 1. Dispersiia.

The dispersion of melanosomes in the dermal melanophores of the Xenopus laevis larvae has been studied by time--lapse cinematography. The process began with the appearance of distally directed melanosome flows in the cell cytoplasm. During the subsequent migration of pigment granules, the flows branched forming branches of the 2nd and higher orders. The whole cytoplasm became filled with a layer of melanosomes. During the dispersion, the movement of melanosomes in a flow is replaced by their dispersion all over the cytoplasm; these processes alternated. In the peripheral part of the cell devoid of melanosomes, membrane vesicles appeared and the cytoplasm was distinctly divided into ecto- and endoplasm. The ectoplasm contained numerous microfilaments and single microtubules, the endoplasm did not contain any cell organelles, except single electron-dense melanosomes. The active role of plasma membrane in the intracellular movement of melanin granules is suggested.

[Activity of exogenous genetic designs, introduced into cells by a ballistic transfection method, in murine ontogenesis]. / Aktivnost' ékzogennykh geneticheskikh konstruktsii, vvedennykh v kletki metodom ballisticheskoi transfektsii, v ontogeneze myshi.

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.