Changes in the physicochemical characteristics of rabbit sclera upon scleral reinforcement

Biochemical analysis and differential scanning calorimetry demonstrated that the connective tissue (capsule) formed around a reinforcing scleroplastic implant is similar to intact sclera, its main component being type I collagen organized in perfect fibrils with cross-linking sufficient for normal thermomechanical properties. DSC also revealed a fraction of collagen with heat-labile ‘immature’ cross-links around implants containing a stimulatory plant product Panaxel, which suggested high synthetic activity of fibroblasts.     

Immunogenicity of the recombinant Bacillus strains with cloned gene of biosynthesis of protective antigen against Bacillus anthracis

Microbe Russian Anti-Plague Research Institute, Saratov A hybrid plasmid pUB110PA-1 demonstrating stable functioning in the cells of Bacillus strains and containing the gene of biosynthesis of Bacillus anthracis protective antigen was constructed. The recombinant strains surpassing the anthrax vaccinal cultures in the secreted synthesis of the protective antigen were obtained and their immunological efficacy was assessed. A single inoculation of Guinea pigs with the dose of 5 x 107 spores of the recombinant strains imparted efficient protection against B. anthracis challenge. Immune responses were characterized by high indices of immunity and titers of antibodies to the protective antigen. In contrast to the anthrax vaccinal preparations, the gene-engineering strains imposed no residual virulence for BALB/n mice and Guinea pigs.     

Factors affecting light penetration in shallow lakes

Light conditions were studied in six lakes of the Danube Delta for a period of 2 years and were described as a function of 12 independent variables forming a data matrix with more than 1000 sample units. Light extinction was explained in percentage of 64% by phytoplankton, of 11% by detritus, of 7% by zooplankton, of 1.4% by dissolved organic matter and of 0.15 by bacterioplankton. The influence of mineral particles was insignificant. Equations are produced here for the relationship to water turbulence, wind intensity and lake depth. The threshold for full water turbulence was between 7 and 8% for a fluctuation domain of critical winds of 3.2–5.4 m s^-1 and for a depth domain of 1–3 m.     

Changes in the Content of Glial Fibrillary Acidic Protein in the Frontal Cortex of Rats during Conditioned Active Avoidance Training

We studied the dynamics of expression of glial fibrillary acidic protein (GFAP) in the frontal neocortex of rats during training for conditioned active avoidance reaction (CAAR). The GFAP content in a cytoskeletal fraction of the frontal cortex tissue was quantitatively estimated with the use of solid-phase immunoenzyme analysis, 2 h and 1, 3, 7, 14, 21, and 30 days after the beginning of training of the animals. It was found that the changes in expression of the filamentous form of GFAP in the neocortex are clearly pronounced and possess a three-phase pattern: the level of GFAP significantly increased within the first hours after the beginning of CAAR training, within 7-14 days this index decreased and became smaller than that in the initial state, and then again rose (with a maximum after 21 days). The obtained data indicate that the neurospecific protein under study is involved in the processes of learning and formation of conditioned memory engrams.     

Carbonic anhydrase in leaves during radish plant ontogeny and glucose effect

Radish (Raphanus sativus L.) plants were grown in a greenhouse in soil at natural illumination, temperature, and CO₂ concentration. A relationship between the activity of soluble carbonic anhydrase (sCA) and the content of soluble carbohydrates (sCH) was investigated depending on leaf position on the stem during plant development. Indices characterizing leaf ageing during the phase of vegetative growth (PVG) (in lower leaves as compared to upper ones) were a decrease in the rate of photosynthetic release of O₂, photosynthetic efficiency, quantum efficiency of photosystem II, and the content of chlorophylls a and b. During PVG and the phase of flower bud formation, the activity of sCA and the contents of sCH, soluble protein, and Glu were the greatest in young (topmost) leaves and declined in the leaves of middle and lower storeys. From the top to the middle leaves, a dependence of sCA activity on the content of Glu or other sCH (without Glu) was direct, whereas, from the middle and the lower leaves, it became inversed. During leaf ageing in vegetatively growing plants and in the phase of budding, the relation between sCA and a relative content of Glu (percent of the rest sCH) was similar to that described above and yielded broken lines, and, during flowering, an inverse relation was observed in the leaves of all three storeys with a low content content of Glu and a low sCA activity. In order to study a dependence of sCA activity on the levels of sCH and Glu during PVG, one half of the leaf was incubated in a thin layer of water at a light schedule: by 12 h of night/day/night + 3-h-long illumination (control material). Within the period of active growth of the hypocotyl up to the storage root formation, the sCA activity and the content of sCH in the leaves incubated in water (control) increased. During a later PVG, both characteristics declined with sCA activity reduced stronger. The rate of the photosynthetic O₂ release changed in accordance with the changes in sCA activity. Incubation of the other half of the same leaf in 20 mM Glu during early PVG brought about a considerable increase in sCA activity as compared with control material. During a later PVG and at a much greater Glu concentration (330 mM), its content in the leaves increased manifold; however, there were no significant changes in the activity of sCA, the content of protein or chlorophyll. It was concluded that the activity of sCA in the radish leaves during PVG was not regulated by the absolute content of sCH or Glu in the leaves but depended on endogenous factors associated with plant development.     

Morphology of gametes of mollusks, echinoderms, and brachiopods in systematics and phylogeny

The morphology of eggs and sperm of echinoderms, mollusks, and brachiopods was studied and compared. The gametes of inarticulate brachiopods (two classes Lingulata and Craniata and two subphyla Linguliformea and Craniaformea) are shown to have significant morphological differences from those of articulate brachiopods (extant class Rhynchonellata, subphylum Rhynchonelliformea). Inarticulate brachiopods have similar sperm morphology to that of primitive brachiopods, bivalves and some polychaetes that have external fertilization. Sperm morphology of articulate brachiopods is similar to that of echinoderms, which are considered to be typical deuterostomate invertebrates. This similarity supports an early deviation of lophophore-bearing animals from Bilateria, before this lineage branched into Protostomia and Deuterostomia. Similar gamete morphology in Lingulata and Craniata supports the view that inarticulate brachiopods should be retained as a supraclass taxon for comparison with other Lophotrochozoa, in particular with phoronids, bryozoans, and mollusks. Based on the new data on the gamete morphology in inarticulate brachiopods, we propose the name Lingulophyles with the type genus Lingula, and for articulate brachiopods Coptothyrophyles with the type genus Coptothyris.     

Selenoprotein W depletion induces a p53- and p21-dependent delay in cell cycle progression in RWPE-1 prostate epithelial cells

The anticancer activity of selenium (Se) has been demonstrated in myriad animal and in vitro studies, yet the mechanisms remain obscure. The main form of Se in animal tissues is selenocysteine in selenoproteins, but the relative importance of selenoproteins versus smaller Se compounds in cancer protection is unresolved. Selenoprotein W (SEPW1) is a highly conserved protein ubiquitously expressed in animals, bacteria, and archaea. SEPW1 depletion causes a delay in cell cycle progression at the G1/S transition of the cell cycle in breast and prostate epithelial cells. Tumor suppressor protein p53 is a master regulator of cell cycle progression and is the most frequently mutated gene in human cancers. p53 was increased in SEPW1 silenced cells and was inversely correlated with SEPW1 mRNA in cell lines with altered SEPW1 expression. Silencing SEPW1 decreased ubiquitination of p53 and increased p53 half-life. SEPW1 silencing increased p21(Cip1/WAF1/CDKN1A), while p27 (Kip1/CDKN1B) levels were unaffected. G1-phase arrest from SEPW1 knockdown was abolished by silencing p53 or p21. Cell cycle arrest from SEPW1 silencing was not associated with activation of ATM or phosphorylation of Ser-15 in p53, suggesting the DNA damage response pathway was not involved. Silencing GPX1 had no effect on cell cycle, suggesting that G1-phase arrest from SEPW1 silencing was not due to loss of antioxidant protection. More research is required to identify the function of SEPW1 and how it affects stability of p53.     

Cyclic structural changes of endoplasmic reticulum and Golgi complex in hippocampal neurons of ground squirrels during hibernation

Repetitive remodeling and renewal of the cytoplasmic structures realizing protein synthesis accompanies the cycling of the ground squirrels between torpor and arousal states during hibernation season. Previously, we have shown the partial loss of ribosomes and inactivation of the nucleolus in pyramidal neurons in the hippocampus CA3 area at each bout of torpor with their rapid and full recovery after warming up. In the present paper, we describe reversible structural changes of the endoplasmic reticulum (ER) and Golgi complex (GC) in these neurons. The transformation of the ER form from mainly granular stacks of flattened cisternae to smooth tubules occurs at every entrance in torpor, while the reverse change happens at arousal. The torpor state is also associated with GC fragmentation and loss of their flattened cisternae, i.e., dictiosomes. In neurons, the appearance of the autophagosomal vacuoles containing fragments of membrane structures and ribosomes in torpor state is a sign of the partial destruction of ER and GC. Granular ER restoration, perhaps through assembly from the multilamellar membrane structures, bags or whorls begins in the middle of the torpor bout, while GC dictiosomes reappear only during warming. The ER and GC completely restore their structure 2–3 h after the beginning of arousal. Thus, hibernation represents an example of the structural adaptation of the nerve cell to deep changes in functional and metabolic activity through both the active destruction and renewal of ribosomes, ER, and GC. Perhaps, namely the incomplete ER autophagosomal degradation in torpor provides its rapid renewal at arousal through the reassembly from the preserved fragments.     

Biochemical studies on the production of neuraminidase by environmental isolates of Vibrio cholerae non-O1 from Bulgaria

Neuraminidase is a key factor in the infectious process of many viruses and pathogenic bacteria. The neuraminidase enzyme secreted by the etiological agent of cholera?- Vibrio cholerae О1?- is well studied in contrast with the one produced by non-O1/non-O139 V.?cholerae. Environmental non-O1/non-O139 V. cholerae isolates from Bulgaria were screened for production of neuraminidase. The presence of the neuraminidase gene nanH was detected in 18.5% of the strains. Тhe strain showing highest activity (30 U/mL),?V. cholerae non-O1/13, was used to investigate the enzyme production in several media and at different aeration conditions. The highest production of extracellular neuraminidase was observed under microaerophilic conditions, which is possibly related to its role in the infection of intestine epithelium, where the oxygen content is low. On the other hand, this is another advantage of the microbe in such microaerophilic environments as sediments and lake mud. The highest production of intracellular neuraminidase was observed at anaerobic conditions. The ratio of extracellular to intracellular neuraminidase production in V. cholerae was investigated. The temperature optimum of the enzyme was determined to be 50?°C and the pH optimum to be?5.6-5.8.