Plasmid inverted repeats provide for duplication or precise excision of DNA inserts

A plasmid containing inverted repeats is constructed in Bacillus subtilis. Insertion of DNA fragments into the plasmid inverted repeats results either in the precise excision of the insert or in its duplication in the opposite inverted repeat. These rearrangements are due to the presence of inverted repeats only. Two recombination events are possibly responsible for these phenomena. During the first step of the recombination two plasmid monomers form a dimer molecule. During the second step the intramolecular recombination between the direct repeats in the dimer structure leads to the formation of two rearranged plasmid monomers devoid of insertion or containing two DNA inserts. Proposed dimeric intermediate is unstable in B. subtilis. However, it is isolated from Escherichia coli recA, cells. Plasmids containing the inverted repeats can serve as a model to study plasmid recombination in B. subtilis cells.     

Restriction map of permuted DNA of Erwinia carotovora temperate bacteriophage 59

The cyclic permutation and terminal redundancy were found in the genomes of Erwinia carotovora temperate bacteriophage 59 by electron microscopic studies. The headful mechanism for bacteriophage DNA cleavage and packaging during the phage morphogenesis was confirmed by the restriction analysis technique. Restriction map of the bacteriophage 59 DNA was constructed for restriction endonucleases BamHI, Bg1II, Eco31, Sa1I, SmaI, EcoRI.     

Effect of the molecular weight of DNA on the effectiveness of plasmid transformation of E. coli K12

The level of plasmid transformation and transfection by the high molecular mass DNA was studied for Escherichia coli mutants having increased efficiency of plasmid transformation by low molecular mass DNA. Decreased level of plasmid transformation and transfection registered in some mutants as compared to the one in wild type strain suggests the specificity of Escherichia coli cells penetration for DNA of different molecular mass.     

Effect of lincomycin and staphylococcal vaccine on the course of experimental staphylococcal sepsis

Therapeutic efficacy of lincomycin used alone and in combination with inactivated staphylococcal vaccine and the effect of these agents on synthesis of antibodies and their content in blood serum were investigated. Lincomycin was shown to inhibit septic processes in the host. After its administration the number of the pathogens in the blood and organs markedly decreased. At the same time, lincomycin lowered antibody synthesis in the lymphoid organs and the content of alpha-antitoxins in blood serum. The use of lincomycin in combination with inactivated staphylococcal vaccine promoted an increase in the number of the antibody forming cells in the spleen and lymph nodes and the content of the antibodies to the staphylococcal alpha-toxin in blood serum of the animals with staphylococcal sepsis.     

Directed synthesis of 2',5'-oligoadenylates with increased stability towards phosphodiesterases

Phosphodiesterase stability of synthetic analogs of 2',5'-oligoadenylates, the mediators of antiviral and antiproliferative action of interferons was analysed. The analogs with a 3'-terminal acyclic nucleoside residue were prepared. These analogs were treated with NIH3T3 cell lysate, mice liver homogenate and snake venom phosphodiesterase. All analogs have demonstrated a high stability as compared with the natural 2',5'-oligoadenylate and its 3'-deoxyderivative. The possible biological activity of these stable analogs of 2',5'-oligoadenylates is discussed.     

Formation of a methylotrophic denitrifying biocenosis in a system of sewage treatment for nitrates

A methylotrophic denitrifying bioenosis composed of hyphomicrobes and paracocci was isolated from the active ooze in a system of sewage purification from nitrates. The morphological and physiological characteristics of the isolated Hyphomicrobium sp. Z-115 and Paracoccus denitrificans Z-100 and Z-121 strains differed from those of the type strains, which made it difficult to identify them and to isolate them as a pure culture. This should be taken into account while determining the agents operating in such purification systems. The rate of growth, the rate of nitrate reduction and the activity of enzymes involved in methanol assimilation are higher in the anabolic syntrophic bicenosis than in its components in pure culture. A combined culture composed of the collection Hyphomicrobium and Paracoccus strains was neither effective nor stable under the conditions of anaerobic growth with nitrate and methanol. Therefore, the natural biocenosis af the purification system cannot be substituted by an artificial one composed of the collection cultures.     

Thyroliberin and its analog lacking hormonal properties stimulate respiratory center activity in the frog Rana temporaria

It has been shown that thyroliberin and its synthetic analogue PR-546 injected into the lymphatic sacs (4.10(-7)-4.10(-9) g/kg) or applied to the medulla oblongata in the bulbar frogs (4.10(-10)-4.10(-12) g/kg) significantly increase the rate of motor respiratory volleys in the hypoglossal nerve. In preparations with the irregular level of the activity of the respiratory center, these drugs enhanced stabilization of the initial level of the rhythm of motor respiratory discharges.     

Effects of male sex hormones on specific uptake and release of 3H-serotonin in the rat hypothalamus in vitro]

With the use of "isotopic method" a study was made of the main parameters of functional activity of serotoninergic elements of hypothalamus--the specific uptake and release of 5-OT. The animals used were sexually mature rats castrated on the first postnatal day. In sexually mature intact males the specific uptake of 3H-5-OT by serotoninergic structures of the anterior hypothalamus was significantly lower than in females. Castration of animals on the first day of life resulted in the increase of specific 5-OT uptake in sexually mature males up to that observed in females. There were no differences between the sexes in the rate of spontaneous release of 5-OT. However, response to K(+)-depolarization in the anterior hypothalamus of intact males was significantly lower than that in females. In the hypothalamus of males castrated neonatally the amplitude of the response to the effect of the depolarizing agent was increase up to the level observed in females. By the results obtained it is indicated that elimination of the effect of male hormones on the first postnatal day results in the increase of 5-OT uptake and release in the hypothalamus of sexually mature rat males.