Morphological and Molecular Genetic Verification of Interspecific Hybrid Salix × zhataica (Salicaceae) from Central Yakutia

Russian Journal of Genetics - The results of morphological and molecular genetic analysis confirming the hybrid nature of Salix × zhataica Efimova, Shurduk et Ahti are presented. In...     

Conformation of the denatured DNA molecule in solutions of different ionic strengths]

The conformation of the denatured DNA molecule of different molecular weights in the solutions of various ionic composition was studied by the methods of viscometry, light scattering and flow birefringence. Formaldehyde purified from metallic ions with the help of ionites was used for fixation of the denatured state of the DNA molecule. It has been shown that theories developed for flexible macromolecules are in a sufficient accordance with hydrodynamical and optical data. The unperturbed dimensions, equilibrium rigidity of the macromolecule in solutions of different ionic strengths, mu, were determined. In the range of mu greater than or equal to 0.005 the length of Kuhn's segment (A) is equal to approximately 40 A and its value increases with an increase of mu. At mu 0.001 A approximately 60 A and mu 0.0005 A approximately 85 divided by 100 A. A relation between intrinsic viscosity and molecular weight of the denatured DNA molecule was established. Data on the flow birefringence in the solutions of the denatured DNA have shown that the sigh of optical anisotrophy of the macromolecule depends on the ionic strength. The observed dependency may be explained only by assuming that ionic strength influences the equilibrium orientation of nitrogen base planes with respect to the main chain of the macromolecule.     

Chemical-enzymatic synthesis and cloning in Escherichia coli of a gene coding for human granulocyte-colony stimulating factor]

Two artificial genes, encoding two forms of human granulocyte colony stimulating factor as products of a normal and an alternative splicing, have been by a chemical-enzymatic way synthesized and cloned in Escherichia coli. The genes are supplied with recognition sites of restriction endonucleases to facilitate the further cassette mutagenesis.     

Characteristics of the intragenic recombination of T4B bacteriophage amber mutants under nonpermissive (su-) conditions

Intragenic recombination of bacteriophage T4B amber mutants in early genes 30, 32, 42, 43, 44, 56 and in late gene 7 in su- cells of Escherichia coli B was studied. The frequency of recombination under such conditions was increased in genes 30, 43 and 7, but it was lowered in genes 46 and 44, and was completely inhibited in genes 32, 42 and 56. The level of stimulation or inhibition of recombination frequencies in early genes was gene-specific and did not depend either on the distances between amber mutations, or on progeny phage maturation delay. On the other hand, the level of recombination stimulation in the late gene 7 was greatly influenced by the distances between amber mutations tested. Wild type alleles arising in su- cells during recombination proved to be functionally active, and their activity caused the increase in progeny phage yield and in a partial removal of phage maturation delay.     

Ultrastructural expression of the process of cell fusion in a rat neurinoma culture exposed to polyethylene glycol

The time course of cell fusion was examined in experiments made with a new cell line derived from rat neurinoma. Exposure to polyethylene glycol (PEG) combined with dimethylsulfoxide led to absorption of cells on plasmalemmas, modification of glycocalyx, disorganization of plasmalemmas in local zones of adjacent membranes, and formation of the common zones of the cytoplasm between neighboring cells. The method used promoted the obtaining of polykaryons, which was accompanied by a decrease in PEG cytotoxicity.     

Role of arachidonic acid in platelet aggregation induced by S. typhimurium endotoxin

The platelet aggregation reaction was used to assess the influence of arachidonic acid (AA), endotoxin (E) S. typhimurium and ADP on platelet aggregation properties. All the three substances induced platelet aggregation. A higher degree of aggregation was attained by the application of E combined with AA and ADP as compared with the effects produced by E and ADP alone. Prolonged incubation of platelet-rich plasma (PRP) samples with E led to an essential decrease of the aggregation degree on ADP addition. Incubation of PRP samples with E and ADP did not evoke any analogous decrease in the platelet aggregation degree. The data obtained indicate that AA stimulates platelet aggregation induced by E and ADP.     

NAG-infection in grass frogs (Rana temporaria) subjected to hypothermia]

Rana temporaria kept under hypothermic conditions approaching anabiosis were inoculated with NAG-vibrios and examined clinically, bacteriologically, histologically, and electron microscopically. Oral inoculation of hypothermic frogs with NAG-vibrios resulted in 18 to 24 hours in the development of acute NAG-infection resembling the cholera-like syndrome, and characterized by general intoxication and local enteropathogenic effects. NAG-vibrios persisted in the frog gastrointestinal tract for a long time after the cessation of the acute period of the disease.