Conformational Properties of Neuromedin NmU-8 and Its Modified Analogs

The three-dimensional organization and conformational properties of NmU-8 neuropeptide and its modified analogs have been studied by modeling and compared with the available data on their biological activity. The effect of single amino acids substitutions on conformational states of the native neuropeptide is discussed. The low-energy conformations responsible for its contractile activity have been revealed.     

Investigation of mechanical properties,morphology, and biodegradability of compositions based on polylactide and polysaccharides

The blends of polylactide with ethyl cellulose and chitosan are obtained in a Brabender mixer under conditions of high temperature shear deformation at different initial ratios of the reagents. The investigation of physicomechanical properties of the compositions has shown that the systems have high rigidity. Polyethylene glycol (PEG) and high-molecular-weight polyolefin polydecene have been added to the compositions in order to improve their elasticity. It has turned out that polydecene scarcely affects the mechanical characteristics, while PEG leads to a noticeable increase in elongation at break. Biodegradability of the compositions is investigated by the mass loss of samples after holding in soil, fungus resistance tests, and the analysis of the film morphology by scanning electron microscopy after holding in soil. It is found that the introduction of the third component (PEG) leads to an increase in biodegradability of the compositions.     

Effects of irradiation by the low-intensity electromagnetic field of the millimetric range on the Daphnia magna culture at various developmental stages

The influence of low-intensity electromagnetic irradiation and exposure to cadmium on survival and reproduction rates of daphnia in the process of their ontogenesis is investigated. The effects of the irradiation are clearly manifested in the toxicological experiments at coactions of the irradiation and cadmium and are weakly exhibited at action of the irradiation itself. At all stages of development, the irradiation does not influence the survival rate of daphnia. However, the irradiation increases their sensitivity to cadmium effects.     

Cytogenetic study on the activity of the ferret embryonic genome before implantation

A cytogenetic study of the activity of the embryonic genome in ferret (Mustela putorius) blastocysts during ∼6 days after their transition from the oviduct to the uterus has been carried out. It has been found that the prolongation in the preimplantation period in the ferret is not accompanied by inhibition of mitosis or activity in nucleolus organizing regions of inner cell mass cells as occurs in species having an obligatory delay of implantation (obligate embryonic diapause). Amitosis of trophoblast cells starts at the periimplantation stage as in other species that do not have obligate diapause. The data obtained are consistent with the hypothesis that the obligatory stage of delayed implantation might occur in some mammals in different taxonomic groups as a result of chromosome mutations affecting the genetic control of the chronology of events (timing) of embryogenesis. Consequently the characteristics of delayed implantation should be different in different species.     

The inhibitors of antioxidant cell enzymes induce permeability transition in yeast mitochondria

In this study we investigated the effects of exogenous and endogenous oxidative stress on mitochondrial membrane permeability transition in yeast cells. E. magnusii yeast was used in the study as it is the only yeast strain possessing a natural high-capacity Са²⁺ transport system. The key reactive oxygen species (ROS) detoxifying enzymes in the yeast cells - catalases (CATs) and superoxide dismutases (SODs) - were fully characterized. At least five isoforms of SODs and only one isoform of CATs were found in the E. magnusii mitochondria. The assessment of the main properties of mitochondrial non-specific permeability under physiological conditions such as dynamics of the membrane potential (?Ψ) and swelling in mitochondria showed that under physiological conditions classical inhibitors of CATs (ATZ - 3-amino-1, 2, 4-triazole) and of SODs (DDC - diethyldithiocarbamate) caused irreversible decline in ?Ψ in the yeast mitochondria. This decline was accelerated in the presence of 500 μM Са²⁺. The combined action of the inhibitors (ATZ + DDC) promoted moderate swelling in the isotonic medium, which was confirmed by transmission electron microscopy. Mitochondrial swelling in the cells exposed to antioxidant system inhibitors was accompanied by typical signs of early apoptosis, namely by chromatin margination and condensation, vacuolization of the cytosol, and damage of the plasma membrane. Here we showed, at both cellular and mitochondrial levels, that the deregulation of oxidant-scavenging enzymes directly leads to the opening of the mPTP, followed by induction of apoptotic markers in the whole yeast cells. Our studies are the first to clarify the highly contradictory data in the literature on mPTP in yeast mitochondria.     

In vivo induction of cytotoxic T lymphocytes in H-2Kbm mutant mice and cross-reactivity of narrowly specific killer clones

Anti-wild-type (B6) H-2Kbm mutant (bm) CTL were induced in the regional lymph nodes by 2 injections (with 2 week interval) of bm mice into foot-pads with B6 irradiated splenocytes. CTL were tested 7 days after the boost, including 3 days precultivation in monoculture (required for high CTL activity in bm). Active bm4 CTL inducible in vivo but not in the mixed lymphocyte culture (MLC), while bm1, bm3 and their F1 hybrids with BALB/c were equally active in both models. In vivo induced bm3 CTL were cloned with B6 irradiated splenocytes stimulators in the presence of rat interleukine-2. Of 9 Thy1.2 positive narrow-specific CTL clones 2 displayed cross-reactivity to allogeneic target cells (TC): the 1st lysed H-2Kk [TC B10.A(2R)] and the 2nd H-2Kd [TC B10.D2(R101)]. The results witness for non-identity of the in vivo and in vitro induced CTL. The variable cross-reactivity of the narrow-specific CTL clones possibly occur because of receptors' affinity difference.     

Retrospective of diatom diversity dynamics in thanatocenoses under climate change

The species diversity of planktonic diatoms in thanatocenoses of bottom sediments in Lake Bol’shoe Miassovo (Southern Urals) has been studied and a reconstruction of the thermal regime of the lake for the last 1000 years is made. It is established that the restructuring of the diatom assemblage and decrease in species diversity in thanatocenoses are caused by rapid climate warming that began in the 19th century in the Southern Urals.