Characterization of a linear extrachromosomal DNA element (pBL1) isolated after interspecific mating between Streptomyces bambergiensis and S. lividans.

Streptomyces bambergiensis S712 harbours a giant linear plasmid PSB1 of 640 kb. After mating with the plasmidless S. lividans strain TK64, conjugants carrying a smaller extrachromosomal DNA element, pBL1, were identified. pBL1 is a 43-kb linear DNA molecule bound to a protein which protects it from attack by both 3'- and 5'-exonucleases. The absence of this protein drastically reduces the transforming efficiency of pBL1. pBL1 shares homology with linear plasmids and chromosomal DNA from S. bambergiensis strains.

[A chronobiological analysis of the lymphocyte dehydrogenase activity in the peripheral blood of rats with Walker 256 carcinosarcoma]. / Khronobiologicheskii analiz aktivnosti degidrogenaz limfotsitov perifericheskoi krovi krys s kartsinosarkomoi Uoker 256.

In a series of experiments the alpha-glycerophosphate dehydrogenase and succinate dehydrogenase (SDH) activities were daily determined simultaneously by the cytochemical method in peripheral blood lymphocytes of normal rats and those with the Walker carcinosarcoma. Using an original algorithm a hierarchy of biorhythms was singled out by a computer according to individual changes in the dehydrogenase activity for each rat. The mean level of succinate dehydrogenase activity was higher than that of alpha-glycerophosphate dehydrogenase. A set of discovered biorhythms and their representation were identical in the both enzymes. The tumor transplantation caused changes in the phase coordination of investigated dehydrogenases in all rhythms and promoted an increase of the succinate dehydrogenase amplitude as compared with the alpha-glycerophosphate dehydrogenase amplitude in certain rhythms. It is concluded that biorhythmological parameters of these enzymes may be used for characterization of the tumor-bearing host.

[Functioning of integrative vectors, based on phage phi C 31, in the strain Streptomyces bambergiensis 712]. / Funktsionirovanie integrativnykh vektorov, sozdannykh na osnove faga phiC31, v shtamme Streptomyces bambergiensis 712.

Actinomycete integrative vectors were constructed. The vectors contain the Escherichia coli plasmid ColE1 replicon, the thiostrepton resistance gene used for selection in Streptomyces and a fragment of the phi C31 actinophage genome with integrative functions. The pS133 and PS135 vector DNAs transformed Streptomyces bambergiensis 712, a strain producing the phosphoglycolipid antibiotic moenomycin. Two types of the transformants were detected. The first type was not affected in the ability to produce moenomycin and the vector pS135 DNA was shown to integrate into the S. bambergiensis 712 genome by the site-specific pattern with the psi C31 phage DNA fragment. The second type of the transformants lost the ability to produce moenomycin. The Southern analysis and cloning of the inserted DNA indicated that in this case the vector pS135 and pS133 DNAs also integrated specifically into the genome but the integration took place not within the phage DNA fragment. Its realization was suggested to proceed via homologous recombination.