Temporary characteristics of the process of stem cell inactivation by allogenic lymphocytes]

The time during which transplated lymphocytes block proliferation and differentiation of non-syngeic stem cells has been determined by retrasplantation of immuno-competent cells from one lethally irradiated recipient to another one. It was established that process of inactivation of CFU by allogeneic lymphocytes proceeds itwo stages. At the first stage, the colonization of recipient's tissues takes place. The colonization of tissues and processes of early recognition are completed during the first hours after transplantation of cell mixtures. At the second stage, the processes of redistribution of injected cells occur and a complete inactivation of stem cells take place. These events are completed in bone marrow and spleen 4-5 days after transplantation of cells mixture, possibly with the participation of lymphocytes sensibilized with the target-cells.     

Dependence of response reaction of root voles to low-intensity irradiation on the initial state of the tissue antioxidant system

There has been studied the response of antioxidant (AO) reaction of the tissue system of the root voles Microtus oeconomus Pall. whose parents belonged to the populations long inhabiting the Republic Komi regions with different degrees of radioactive contamination on an additional radiation action at low doses. Differences have been revealed in the phospholipid content, activities of AO defense, intensities of processes of lipid peroxidation (LPO) in tissues of the vole offspring caught in the control and contaminated regions. It has been revealed that direction and degree of changes in the offspring tissues after the additional action are determined by the parameter value in the non-irradiated animal group. Intensity of the LPO processes in liver and brain was leveled after the long low-intensity irradiation. The obtained data and analysis of literature indicate that at predicting effects of chronic action of low doses of a damaging factor both in experiment and in the natural habitation, it is necessary to take into account initial characteristics of biological objects.     

Dependence of response reaction of root voles to low-intensity irradiation on initial state of the tissue antioxidant system

There has been studied the response of antioxidant (AO) reaction of the tissue system of the root voles Microtus oeconomus Pall., whose parents belonged to the populations long inhabiting the Republic Komi regions with different degrees of radioactive contamination, on an additional irradiation at low doses. Differences have been revealed in the phospholipid content, activity of AO defense, intensity of processes of lipid peroxidation (LPO) in tissues of the offspring of voles caught in the control and contaminated regions. It has been revealed that direction and degree of changes in the offspring tissues after the additional action are determined by the parameter value in the non-irradiated animal group. Intensity of the LPO processes in liver and brain was leveled after the long low-intensity irradiation. The obtained data and analysis of literature indicate that at predicting effects of chronic action of low doses of a damaging factor both in experiment and in the natural habitation, it is necessary to take into account initial characteristics of biological objects.     

Accumulation of calcium in human common iliac artery, aortic valve, xiphoid process, costal cartilage, posterior longitudinal ligament, trigeminal nerve, and rib accompanied by increase of magnesium

To examine whether an accumulation of Ca in the tissues was accompanied by an increase of Mg, the authros investigated the relationships between Ca and Mg contents in the common iliac arteries, aortic valves, xiphoid processes, costal cartilages, posterior longitudinal ligaments, trigeminal nerves, and ribs by inductively coupled plasma-atomic emission spectrometry. After the ordinary dissections by medical students were finished, the common iliac arteries, aortic valves, xiphoid processes, bilateral the fourth costal cartilages, posterior longitudinal ligaments between the fourth and fifth cervical vertebrae, trigeminal nerves, and bilateral the sixth ribs were resected from the subjects and elements were determined. It was found that there were extremely significant direct correlations between Ca and Mg contents in all of the common iliac arteries, aortic valves, costal cartilages, posterior longitudinal ligaments, and trigeminal nerves, whereas there were significant direct correlations in both the xiphoid processes and ribs. As for the tissues containing Ca higher than 20 mg/g, the average mass ratios of Mg/Ca were similar among the seven tissues. As Ca increased in all of the common iliac arteries, aortic valves, xiphoid processes, costal cartilages, posterior longitudinal ligaments, trigeminal nerves, and ribs, Mg increased simultaneously in the seven tissues.     

Dependence between the rate of RNA synthesis and the CTP-synthetase activity of different rat and chicken tissue

The rate of total RNA synthesis determined by the method of Bukher and Sheffield in different tissues of rats and chickens decreases as follows: kidneys greater than liver greater than duodenum mucosa. The activity of CTP-synthetase (EC 6, 3, 4, 2) determined in vitro and in vivo by the method suggested correlates with the rate of total RNA synthesis in the kidneys and liver tissues of rats and chickens. It is shown that 34-35% of CTP synthetized de novo in the chicken tissues and 31-34% in the rat tissues are used for RNA synthesis. At the same time 75-90% of CTP incorporating into RNA is formed by salvage pathway.     

Specific features of accumulation of Cu,Ni, Zn,Cd, and Hg in two whitefish <Emphasis Type="Italic">Coregonus lavaretus</Emphasis> (L.) morphs inhabiting the Inari-Pasvik lacustrine-riverine system

The spatial regularities of the accumulation of heavy metals in two ecological morphs of whitefish of the Pasvik River (northern Fennoscandia) under long-term pollution have been investigated. It was revealed that the accumulation of priority pollutants (Ni and Cu) in fish declines the further you go from the source of pollution. The concentration of Hg in the tissues of fish from the Pasvik River was determined for the first time. It was found that metal accumulation depends on the ecological morphs of the fish, the natural conditions of the waterbodies, and the intensity of pollution. The specific features of heavy-metal distribution in the “bottom sediment-fish organism” system were determined. These may indicate the heterogeneity of the pollution processes of the Pasvik system of waterbodies.     

Changes in the proteolytic activity of tissues during aging

The intensity of proteolytic processes and qualitative composition of autolysis products of the brain, liver and testicle tissues of young and old rats were studied. The gel-chromatographic analysis (Sephadex G-15 and G-50) revealed no considerable amount of high-molecular peptides (1500 Da and over) before and after autolysis. The measurement of the quantity of free amino groups in the gel-chromatographic fraction after the complete acid hydrolysis has confirmed that result. The low-molecular peptides and free amino acids, are the main products of the tissue autolysis. The intensity of proteolytic processes, determined by an increase in the amount of amino acids depends on the autolysis duration and age of animals. The total increment of amino acids in the brain and liver tissues of old animals for the first hour of autolysis has been higher by 102 and 219% as compared to young ones. The autolysis of testicles of the young and old animals after the first hour of incubation is characterized by the same intensivity. Such a regularity is not revealed when analyzing the same processes by the Lowry method.     

Modeling dynamics of decompression disease risk under high-altitude decompression

The probabilistic model of the development of decompression disease was modified by introducing the corrections into its equation that refine the dependence of the risk of the injury of tissues by gas bubbles on their blood supply and the intensity of nucleation processes. The parameters of the "worst" virtual tissues and theoretical curves were determined that correspond to the empirical data on the cumulative probability of the development of decompression disease symptoms during some procedures of high-altitude decompression. It was shown that the parameters of these hypothetical tissues depend on the final pressure, the physical load, and the duration ofpreoxygenation. The ways of constructing a working hypothesis about the gradation of real body tissues with respect to the parameters determining the risk of their injury by bubbles and developing the method for the theoretical prognosis of the probability of development of decompression disease during any decompression procedure are discussed.     

Angiogenesis in the female reproductive system.

In adult tissues, capillary growth (angiogenesis) occurs normally during tissue repair, such as in healing of wounds and fractures. Rampant capillary growth is associated with various pathological conditions, including tumor growth, retinopathies, hemangiomas, fibroses and rheumatoid arthritis. The female reproductive organs (i.e., ovary, uterus, and placenta) exhibit dynamic, periodic growth and regression accompanied by equally dramatic changes in rates of blood flow. It is not surprising, therefore, that they are some of the few adult tissues in which angiogenesis occurs as a normal process. Thus, the female reproductive system provides a unique model for studying regulation of angiogenesis during growth and differentiation of normal adult tissues. Ovarian, uterine, and placental tissues recently have been shown to contain and produce angiogenic and anti-angiogenic factors. This review discusses the current state of knowledge regarding angiogenic processes and their regulation in female reproductive tissues. In addition, implications of this research for regulation of fertility as well as for control of angiogenesis in other normal and pathological processes are discussed.     

The mechanisms of the action of fluorine on periodontal tissues]

It is stated that fluoride intoxication promotes a sharp intensification of the peroxidation processes in the parodontium tissues. It is caused by a respirator explosion of neutrophils, a decrease in activity of antioxidant system enzymes, thus leading to disturbances of microcirculation and blood coagulation, ischemia development. The last factor can retard the enzymatic oxidation in a cell due to hypoxia, injures lysosomal membranes promoting partial autolysis of parodontium tissues, cell structures, intercellular substance. The interaction of blood with destructive elements of cells and collagen favours the development of trombohemorrhagic reactions in the parodontium tissues. A generalized damage of parodontium arises which intensifies under the effect of any other pathogenetic factors.     

Molecular and cellular bases for the effects of interferon

The data on the molecular mechanisms of interferons activity are analyzed. The analysis is based on the assumption that interferons are the substances of the hormonal nature. The initial step of the different interferons effects is attempted to be explained by the existence of the molecular and cellular reactions common for its realization. The dependence of the final results of interferons action on the metabolic processes in different cells and tissues determined by the specific functions and physiology of the latter is assumed.     

Cloning, chromosomal organization and expression analysis of Neurl, the mouse homolog of Drosophila melanogaster neuralized gene

The Drosophila neuralized (neur) gene belongs to the neurogenic group of genes involved in regulating cell-cell interactions required for neural precursor development. neur mutant phenotypes include strong overcommitment to neural fates at the expense of epidermal fates. The human neuralized homolog (NEURL) has been recently determined and found to map to chromosome 10q25.1 within the region frequently deleted in malignant astrocytomas. Because of its potential importance in developmental processes, we analyzed the structure of the mouse homolog, Neurl, and its expression pattern in embryonic tissues. Neurl activity is detected from early developmental stages in several tissues and organs including neural tissues, limbs, the skeletal system, sense organs and internal organs undergoing epithelial-mesenchymal interactions. Neurl encodes a polypeptide associated with the plasma membrane but also detected in the cytoplasm. Similarly to the Drosophila gene, mammalian neuralized may code for an important regulatory factor.     

On the Validity of Plasmodesmograms*

Because the operation of plasmodesmata is of paramount importance for the integrative action of tissues and organs, it is important to quantify the symplastic continuity. An attempt to visualize the intercellular communication pathways in plant tissues is the plasmodesmogram, a two-dimensional diagram of plasmodesmatal frequencies. Plasmodesmograms assume that the greater the frequency of plasmodesmata, the greater is the potential for symplasmic communication. In fact, however, the validity of plasmodesmograms hinges on the premise that plasmodesmata are uniform in structure and functioning. In view of recent findings that plasmodesmata are gatable channels with different functional diameters, a correlation between plasmodesmatal frequency and the rate of intercellular communication - including transport - is disputable and the concept of the plasmodesmogram needs to be re-examined. Its validity appears to vary with the developmental stage and the nature of the plant tissue. Our over-all conclusion is that plasmodesmograms are an acceptable device for coarse (qualitative) assessment of intercellular transport pathways in mature phloem tissues. Pathways identified by plasmodesmograms often correlate with the physiologically determined modes of photosynthate transport. Whether this applies to differentiated tissues, in general, remains to be elucidated. The value of plasmodesmograms for developmental phyisology seems to be limited, as developmental processes coincide with temporary or permanent closure of plasmodesmata.     

Functional states of antioxidant enzymatic complex of tissues of Mytillus galloprovincialis Lam. under conditions of oxidative stress

Materials are summarized on reaction of enzymatic antioxidant (AO) complex of tissues molluscs of the genus Mytilus on oxidative load of different intensity. It is shown that with increase of the level of oxidative stress there is observed a rise of activities of glutathione reductase (GR) and glutathione peroxidase (GP) as well as increases the turnover rate of glutathione (GSH) in tissues. Then the toxic load is compensated by an elevation of activities of enzymes of low affinity to hydroperoxides, specifically of catalase. In the glutathione system it is possible to identify several relatively steady states: processes of low, moderate, and high intensity. In individual tissues, functioning of the AO system seems to be directed not to detoxication, but to generation of reactive oxygen species (O₂ ^·?, superoxide dismutase), which probably is determined by specifics of their running processes (destruction of damaged byssus threads). The AO complex of molluscs is distinguished by high lability and sensitivity both to physiological states (spanning) and to action of factors of anthropogenic nature (cationic detergents). Responses of the mussel AO complex to natural states and toxic action are comparable between each other, which are necessary to be taken into account at diagnostics of the state of the aquatic environment.     

Role of temperature in regulation of the life cycle of temperate fish

The review provides information on adaptive responses of fish metabolic processes in response to temperature reduction of habitat, including the direction of adjustment of energy metabolism and mechanisms to improve the adaptive capacity and reparative capacity of tissues in response to lower temperatures. It presents data on the effect of temperature on the reproductive function of fish and fish development processes in the early stages of ontogeny.     

Colchicine-binding measurements of tubulin in variously sampled and incubated tissues from the mammalian brain

Tissue preparations from the brain of rats and guinea-pigs were examined for their activity in binding isotopically labelled colchicine, as a measure of their content of tubulin. The amount of binding material extracted into a cold buffered solution was unaffected by keeping tissues at 0°C. It diminished by one quarter when tissues were incubated at 37°C in bicarbonate glucose salines for 1–2 h. This diminution increased when glucose was omitted from incubating solutions and was less when tissues were stimulated electrically. It was modified also by the calcium content of the incubation fluids. Of the binding activity lost on incubation only a little was recovered in surrounding fluids. About half the colchicine-binding activity of the tissues was not extracted by the solution employed; this particulate-attached activity changed little, if at all, on normal incubation but diminished when incubating fluids contained a cyclic AMP-fluoride theophylline mixture which was known to modify tubulin assembly.The retention of both categories of colchicine-binding under normal conditions of incubation is consistent with the ability of such tissues to perform microtubule-dependent processes, notably cytoplasmic transport. Examination of the isolated tissues by the methods reported is of value in indicating which of various factors known to affect separated tubulin and microtubule structures, operate in a cell-containing system under chosen experimental conditions.     

Tissue specific characterisation of Lim-kinase 1 expression during mouse embryogenesis

The Lim-kinase (LIMK) proteins are important for the regulation of the actin cytoskeleton, in particular the control of actin nucleation and depolymerisation via regulation of cofilin, and hence may control a large number of processes during development, including cell tensegrity, migration, cell cycling, and axon guidance. LIMK1/LIMK2 knockouts disrupt spinal cord morphogenesis and synapse formation but other tissues and developmental processes that require LIMK are yet to be fully determined. To identify tissues and cell-types that may require LIMK, we characterised the pattern of LIMK1 protein during mouse embryogenesis. We showed that LIMK1 displays an expression pattern that is temporally dynamic and tissue-specific. In several tissues LIMK1 is detected in cell-types that also express Wilms' tumour protein 1 and that undergo transitions between epithelial and mesenchymal states, including the pleura, epicardium, kidney nephrons, and gonads. LIMK1 was also found in a subset of cells in the dorsal retina, and in mesenchymal cells surrounding the peripheral nerves. This detailed study of the spatial and temporal expression of LIMK1 shows that LIMK1 expression is more dynamic than previously reported, in particular at sites of tissue-tissue interactions guiding multiple developmental processes.     

Alternative promoter usage of the membrane glycoprotein CD36

Background  

CD36 is a membrane glycoprotein involved in a variety of cellular processes such as lipid transport, immune regulation, hemostasis, adhesion, angiogenesis and atherosclerosis. It is expressed in many tissues and cell types, with a tissue specific expression pattern that is a result of a complex regulation for which the molecular mechanisms are not yet fully understood. There are several alternative mRNA isoforms described for the gene. We have investigated the expression patterns of five alternative first exons of the CD36 gene in several human tissues and cell types, to better understand the molecular details behind its regulation.     

Phytochemicals at the plant-insect interface

Opportunities for genetic engineering of natural products are increasing, while discovery and development of synthetic insecticides and developmental regulators are declining. However, discovery and potential applications of natural compounds are constrained by present ecological knowledge and theory. Biochemistry offers additional perspective to chemical interaction across the interface between plant and herbivore. Phytochemical effects on an insect herbivore may be determined by physical, chemical, and biotic characteristics of the microenvironment during phytochemical transfer between plant and insect. The midgut lumen is often overlooked as part of this microenvironment. It initially determines rates of metabolism and uptake of phytochemicals into hemolymph, and ultimately the quantity of a compound seen by affected tissues. Additive processes such as absorption, binding, and transport by proteins in hemolymph may ultimately prove more crucial to toxication than subtractive processes such as metabolism and excretion. Uptake and transport of coumarins in hemolymph are being studied in larvae of the citrus root weevil Diaprepes abbreviatus. Studies with synthetic 7-amino-3-phenyl coumarin (coumarin-10) have preceded studies with natural coumarins. The fluorescence properties of coumarin-10 have enabled determination of absorption and binding to hemolymph proteins.     

Cell fate choices in Drosophila tracheal morphogenesis

The Drosophila tracheal system is a branched tubular structure that supplies air to target tissues. The elaborate tracheal morphology is shaped by two linked inductive processes, one involving the choice of cell fates, and the other a guided cell migration. We will describe the molecular basis for these processes, and the allocation of cell fate decisions to four temporal hierarchies. First, tracheal placodes are specified within the embryonic ectoderm. Subsequently, branch fates are allocated within the tracheal placodes, prior to migration. Localized presentation of the FGF ligand, Branchless, to tracheal cells that express the FGF receptor, Breathless, guides migration. Once cell migration is initiated, distinct cell fates are determined within each migrating branch. Finally, inhibitory feedback mechanisms ensure the correct assignment of these fates. Tracheal cell fate choices are determined by signaling cascades triggered by signals emanating from the tracheal cells, as well as by ligands produced by adjacent tissues.