L. M. Chailakhyan

Opposite Effects of Low Oligomycin Concentrations on the Apoptosis of Normal and Tumor Cells

Oligomycin is widely used in laboratory studies as an ATPase inhibitor. It binds to F 0 F 1 ATPase and inhibits the mitochondrial proton pump [1], which results in respiration suppression and a decrease in the cell ATP content. Oligomycin concentrations completely inhibiting respiration vary from 80 to 300 nmol/l for different cell types [2]. A decrease in ATP concentration has been previously assumed to be the only cause of the toxic effect of oligomycin on cells. Recent data suggest, however, that some oligomycin effects do not depend on ATP. For example, the inhibition of Baxinduced apoptosis does not depend on ATP [1]. It is supposed [1] that, in this case, a blockage of mitochondrial pore opening accounts for the oligomycin effect.

Comparative analysis of plasticity of neuro-neuronal and neuroglial encapsulating interactions of molecular layer of isolated frog cerebellum exposed to excess L-glutamate and NO-generating compound.

In our previous works [1–4], we sought for the morphological correlates of plasticity of the synapses of parallel fibers (PFs) on Purkinje cells (PCs), studied in electrophysiological experiments with frog cerebellum in vitro [2]. These studies demonstrated a broad diversity of cell responses to external effects (such as electric stimulation of various afferent inputs on PCs and disbalance of natural cerebellar neurotransmitters) [2–4]. It was found that one of the most vivid cell-plasticity responses is encapsulation, observed in the neuro-neuronal and neuroglial interactions in the PF–PC synapses (e.g., in neurotransmitter disbalance) [3, 4]. The purpose of this work was to compare these neuro-neuronal and neuroglial encapsulating plasticity interactions under experimental conditions simulating extremal regimens of cerebellar function. The latter were modeled using excess Glu and nitric oxide (NO) in vitro , because these compounds are tightly functionally related to and play a key role in functioning PF–PC synapses. This problem statement allowed us to study not only pathological, irreversible reactions but also to find compensatory adaptive plasticity changes that determine the efficiency of functioning the main cerebellar synapses (the synapses of parallel fibers on Purkinje cells) and are, therefore, related to the problems of memory in the cerebellum.

The effects of immunomodulating peptides on the preimplantation development of mouse embryos.

Hormones and growth factors produced in the mother’s organism play a key role in regulation of cell division and differentiation in early mammalian embryos [1]. The culturing of preimplantation embryos in vitro allows studying the direct effect of some factors and determine their specific roles in the morphogenetic events occurring at this ontogenetic stage. It is known that the proopiomelanocortin gene is expressed during embryogenesis [2]. It was shown that, in this period, proopiomelanocortin is cleaved to several active peptides, including adrenocorticotropic hormone (ACTH(1–39)), β -endorphin(1–27), and β -endorphin(1–31). There is reason to assume that these peptides may play a key role during mammalian embryonic development [3].

The Medium for Microsurgical Transfer of Nuclei in Mice: The Osmolarity Phenomenon

At present, various methods and techniques of cellular engineering are widely used for solving both fundamental and applied problems, and the demand for all these methods is constantly increasing. Recent advances in cellular engineering, such as microsurgical artificial fertilization, creation of chimeric (mosaic) and transgenic animals, reconstruction of embryonic cells with the use of genetic material from cells of different types, cloning, culturing of early embryos and stem cells in vitro , and prolonged preservation (cryopreservation) of various animal cells and tissues, are extremely important for medicine, agriculture, and the conservation of the gene pools of endangered species. In this connection, the problem of the compatibility of the cellular engineering techniques with life becomes topical. Of special importance are the estimation of cell viability upon these manipulations and the search for optimal experimental conditions minimizing the deleterious effects of cellular engineering. Here, we discuss the factors that affect the survival and subsequent development of reconstructed mouse embryos obtained via nucleus transplantation. It has been demonstrated that the media currently used in microsurgery are not adequate to the subsequent formation of the embryo. We propose a medium increasing the viability of oocytes during the microsurgical reconstruction of mouse embryos. Mature oocytes of various mammalian species, including humans, are the main objects of microsurgical manipulations. However, zygotes and two-cell embryos are used for some special purposes, e.g., serial nucleus transplantation or creation of chimeric animals [1–3]. Usually, the media that were selected for culturing intact embryos are used for manipulations with cells and their subsequent culturing in vitro [4–8]. Although some authors note that cells treated during the operation need special conditions, including special media [9], these conditions have not been determined. Apparently, cells need special conditions not only after, but also during the microsurgery operation, so that an optimal medium may determine the success of subsequent development. In microsurgery, traditional media supplemented with cytochalasin B, cytochalasin D, and, in some cases, colcemid are used. These substances, which decondense the cytoskeleton, are necessary but not sufficient factors of cell survival. We found that the osmotic characteristic of the culture medium was an equally important factor.

The Possible Role of Nitric Oxide in Interaction between Neurons

Numerous data accumulated in recent years indicate that nitric oxide (NO) is a representative of a new type of neuronal messenger molecule involved in learning and memory processes [1]. It is also well known that, to some extent, learning is associated with long-term potentiation (LTP) or long-term depression (LTD) of signal transmission through synapses during repetitive stimulation of neurons. It was also reported that NO is involved in modulation of synaptic plasticity [2–5]. For example, nitroarginine, an inhibitor of NO synthase, was found to be an LTD blocker in rat hippocampus (CA1 region) [4]. However, in addition to inhibitors of NO synthase, an inhibitor of soluble guanylate cyclase can also suppress LTD. It is well known that, in addition to NO, activation of the cyclic-GMP biosynthesis catalyzed by soluble guanylate cyclase is also involved in both intracellular and intercellular signaling [5]. It was also shown that the long-term depression induced by insulin-like growth factor (IGF-1) during the glutamate-induced release of gamma-aminobutyric acid (GABA) from Purkinje’s cells requires simultaneous activation of signaling systems such as NO and protein kinase c [6]. These data suggest that the enzyme systems responsible for both NO production and transmission of NO-mediated signals are capable of modifying both LDP and LDD in brain neurons.

Social Stress in Groups of Mice: Methods for Recording Conflicts and Their Consequences

When animals intensely use a territory, they form groups whose members are linked with one another by domination–subordination relationships [1]. This system of relationships is generally called hierarchical. The formation of the group and changes in its structure are determined by aggressive interactions that establish or change the structure of domination–subordination. This is accompanied by social stress determined by the mutual interactions of the animals in the group. Social stress causes various diseases and can even lead to death of the animals [1, 2]. The hierarchical organization of the groups is characteristic not only of nonhuman animals, but also of humans. In humans, social stress is considered one of the main causes of neurological disorders [3], circulatory diseases [4], tumors [5, 6], and other diseases [7]. The necessity of experimental study of social stress, its effects, and measures to prevent or mitigate its consequences is obvious.

The Role of the Smooth Endoplasmic Reticulum in Neuronal Adaptation to Fatiguing Stimulation

The adaptation of an organism to an environment is known to occur because of the plasticity of the central neurons and their ability to change their reactivity after sequential irritations of their receptive structures [1]. The neuronal plasticity may be expressed at both preand postsynaptic levels. By now, it has been demonstrated that presynaptic mechanisms are related to specific ultrastructural variability of the synaptic contacts [2–4]. Little is known about the postsynaptic mechanisms; however, there is evidence that they are based on structural rearrangements of the endoplasmic reticulum. In this organoid, we recently revealed significant structural changes correlating with the functional state of cells after a long-term fatiguing stimulation of neurons [5–7]. To study the changes in the smooth endoplasmic reticulum (SER) during a long-term neuronal adaptation to repetitive stimuli, we conducted a quantitative analysis of the rearrangements occurring in neurons prior to and after fatiguing stimulation.

Spatiotemporal Analysis of the Contraction of a Fragment of the Unfolded Frog Atrium

Earlier [1], a fundamentally new objective was formulated in the field of various cardiac-rhythm disorders. Cardiac-rhythm disorders are a topical problem of medicine, because these are highly prevalent diseases often leading to cardiac arrest and sudden death. The objective was formulated as follows: the study of the spatiotemporal pattern of myocardium contraction and the efficiency of its functioning as a pump in normal and various pathological modes. The point is that, until now, different disturbances of the natural synchronous functioning of the heart (extrasystoles, various arrhythmias, etc.) have been studied in terms of pathological excitation modes emerging in the myocardium. This was not unexpected, because a comprehensive theory of the spread of excitation waves in inhomogeneous excitable media was developed in the 1960s and 1970s [2–8], and this theory sufficiently explained the mechanisms of various cardiac arrhythmias. For example, new methodologies using special fluorescent stains sensitive to changes in membrane potential have made it possible to record the spatial pattern of the generation of spiral excitation waves in the hearts of experimental animals under the conditions predicted by the theory.

Some theoretical problems of cloning in the light of comparative analysis of early development in mammals.

Cloning of mammals, one of topical problems of modern biology, raises many questions related to the specificity of mammalian ontogeny. One of them is, why do most embryos obtained by transplantation of somatic nuclei develop only to the blastocyst stage? At present, the main approaches to increasing the cloning efficiency are improvement of the preparation of donor cells and the techniques that could help the researchers to overcome difficulties encountered in the course of experiments. We, however, think that development of theoretical problems concerning the general strategy of cloning requires greater attention to normal development of mammals and new understanding of the specificity of early ontogenetic stages. In these studies, the comparative embryological approach may be helpful. Mammalian ova are secondarily alecithal structure. This determines the specificity of their embryonic development, which drastically differs from those of other Amniota, whose ova are polylecithal. The small amount of yolk contained in mammalian ova is expelled during the first cleavage divisions, and blastomeres are entirely devoid of it. Ova have no distinct polarity; they undergo complete asynchronous cleavage, with the division of one of the two first blastomeres occurring in the meridional plane and the other, in the equatorial plane. The blastomeres remain totipotent for a long time and are capable of interphase transposition [1, 2]. These characteristics preclude comparison of mammalian early development with those of other higher vertebrates and lower vertebrates. However, the early development of mammals strongly resembles the development of some lower metazoans, namely, metagenetic hydromedusae, which I.I. Mechnikov studied in detail back in 1886. Their ova are not strictly polar; many hydromedusae are characterized by anarchical cleavage accompanied by turns and reorientation of blastomeres. Blastomeres are highly totipotent and, once separated, can give rise to new individuals [3]. The cleavage of the blastomeres of both hydromedusae and mammals results in a dense ball of cells termed morula. In hydromedusae, the morula is transformed into a planula, which comes out of the envelope and becomes a free-living larva. In mammals, the morula develops into a blastocyst, which has a shape of a hollow ball whose wall (the trophoblast) consists of one layer of large, elongated cells, with an aggregation of small cells (the so-called internal cell mass) attached to its internal surface.

Prolongation of the Normoglycemic Period in Animals with Acute Experimental Diabetes by Means of Various Types of Tissue Transplantation

Diabetes is well known to reduce life expectancy. Blindness, limb amputation, renal insufficiency, cardiovascular complications, and neurophathies are much more frequent in patients with diabetes than in the general population. Suffice it to say that the risks of myocardial infarction and stroke are twofold increased in these patients. Even more frustrating is the fact that, according to world statistics, only 50% of the patients with diabetes mellitus type I survive until the age of 50 years. Other patients die mostly of terminal renal insufficiency at an age of 20 to 40–50 years [1–3, etc.]. In this study, we developed an experimental model to follow up various physiological changes in an animal body during initiation and progression of alloxan diabetes and after a compensatory transplantation. We also attempted to increase the duration of the normoglycemic period in the experimental animals via treating them with natural immunomodulating agents characteristic of different developmental stages. This approach proved to be helpful in obtaining a longer period of normoglycemia in the operated rats. Up to now, immunological incompatibility between the donor and recipient tissues remains among the main problems of transplantology. For example, cultured insulin-producing islet cells of the pancreas transplanted intraperitoneally to rats with experimental diabetes survived for only nine days in the recipient’s body [4]. A generally used immunosuppressor, cyclosporine A, failed to prolong the graft survival (in the case of transplanted islet cells, the survival time was even lower, namely, 8.14 days) because of a high toxicity of this agent [4]. Packing of the islets into semipermeable alginate-poly-L-lysine capsules prior to transplantation was another way to promote graft functioning. However, this approach only provides an insignificant prolongation of graft survival (to 15.8 days) [4]. Longterm cyclosporine A therapy is known to have an adverse effect on blood parameters and to cause atrophy of lymphoid organs. Suppression of immune control over genetic identity of somatic cells leads, in turn, to an increased risk of tumors [5]. According to D. Puke a leading researcher of diabetes in the United Kingdom, the benefit from islet transplantation is not as high as the injurious effect of immunosuppression, at least during the period of graft functioning, much less can it justify the cost of islet isolation and transplantation and the subsequent immunosuppressive therapy [6]. Transplants of other tissues also exhibited poor survival; e.g., bone marrow cells transplanted into the thymic region only survived for eight days [7]. Therefore, we tried to use natural immunomodulating agents normally detectable at various developmental stages of the organism. These are glucagon released by alpha-cells of islands of Langerhans, thymus tissue, and the placental tissue complex [8–12, etc.].