Effects of human cultural neuronal and mesenchymal stem cells on the rat learning and brain state after acute hypoxia

The aim of the study was to compare the effects of neurotransplantation of cultural neural stem cells (NSC) and mesenchymal stem cells (MSC) on the rat behaviour and brain state after acute hypoxia. It was shown that development of two-way avoidance defensive conditioning in a shuttle box improved in rats-recipients with NSC, but not MSC as compared to control. Both the transplants of NSC and transplants of MSC exert neuroprotective influence on the rat brain. NSC both in vitro (before transplantation) and in vivo (on day 27 after transplantation) gave rise to all neural cell types: stem/progenitor cells, precursors of neurons and glia, neurons and glial cells. MSC population in vitro and in vivo (on day 10 after transplantation) consisted of fibroblast-like cells which were eliminated by day 20 after transplantation and were surrounded by reactive glia. We suggest that effects of NSC may be connected with their good survival and potential to differentiate into neurons and with trophic influence on the brain of recipient, whereas MSC only have possible positive trophic effect at early stages after transplantation.     

Study of dominant symbiotic mutants of pea <Emphasis Type="Italic">Pisum sativum</Emphasis> L.

Phenogenetic studies of four symbiotic hypernodulating mutants of pea (Pisum sativum L.) induced from seeds of cultivar Rodno by chemical mutagen EMS were conducted. All mutants have improved symbiotic traits, i.e., an increased number of root nitrogen fixating nodules and high activity of nitrogenase. Symbiotic traits were shown to be inherited dominantly. Mutants grown in the field or in a greenhouse showed superiority over the original cultivar in productivity. An important feature of hypernodulating mutants was found that is responsible for the appearance of high-height productive plants in F₂ after crossing mutants and the original cultivar. Constant lines retaining the ability for high-level production up to the F₅ generation were created based on individual plants.     

4'-Thio-5-ethyl-2'-deoxyuridine 5'-phosphonates: synthesis and antiviral activity

A number of new 5'-phosphonate derivatives of 4'-thio-5-ethyl-2'-deoxyuridine (TEDU) were synthesized. These compounds displayed a low cytotoxicity and, except for TEDU 5'-fluorophosphate, antiherpes activity similar to that of 9-[(2-hydroxyethoxy)methyl]guanine (acyclovir) and 9-(4-hydroxy-3-hydroxymethylbut-1-yl)guanine (pencyclovir). 5'-Ethoxycarbonylphosphonate and 5'-aminocarbonylphosphonate of TEDU were also found to suppress the reproduction of herpes simplex type 1 virus, which is resistant to acyclovir.     

Bioreactor with a semi-fixed packing: anaerobic lactose to lactic acid fermentation

The bioreactor with a semi-fixed packing consists of frames with stretched “Raschell”-type sacks on them. This construction enables the attainment of a larger interfacial area of the biofilm carrier per unit reactor volume as well as the easy removal of the exausted biomass at certain biofilm thickness. In the present paper the batch anaerobic conversion of lactose to lactic acid in this reactor with immobilized bacteria Lactobacillus casei is studied. The dilution rate of the feeding substrate solution was 1?mm/s. Comparison of our experimental results with data, obtained for free cells and other construction of bioreactors with immobilized cells is made. It is shown that the used immobilised biocatalyst is superior to free bacterial cells, or attached to the inner pores of polyurethane foam.     

Fractionation and specificity of DNA methylases from the Escherichia coli SK cells

Summary Specificity of DNA methylation enzymes from the E. coli SK cells and conditions for their separation have been investigated. Column chromatography on carboxymethylcellulose permits fractionation of methylase activity into six discrete peaks whose specificity to the methylated base has been determined in vitro with H³-SAM as precursor. All methylases specific for adenine produced 6-methylaminopurine, all methylases specific for cytosine yielded 5-methylcytosine.The first enzymatic activity peak containing cytosine methylase free of traces of adenine-methyiating activity (E₁), and the second peak containing both the enzymes (E₂) were not adsorbed on the ion exchanger and went off the column with the effluent (column buffer). Adenine specific methylase E₂ is retarded to a small extent during the passage through the column. The second adenine methylases (W) was characterized by weak bonds with the ion exchanger and was removed when washing the column with column buffer. The elution with NaCl gradient produced successively three enzymatic activity peaks: adenine methylase (G_I), cytosine methylase (G_II), and one more adenine methylase (G_III) removed from the column by 0.16 m, 0.24 m and 0.43 m NaCl respectively.Using a new modification of the complementary methylation test, the specificity with regard to recognition site was examined for all enzymes, except for W and G_III, which were extremely unstable. The adenine methylases E₂ and G_I and the cytosine methylases E₁ and G_II were shown to recognize different sites and to be different enzymes. In view of the drastic differences in their chromatographic behaviour and physical stability, the adenine methylases W and G_III are probably also different enzymes.