[The molecular cloning of a genetic region determining the surface exclusion system of the F-like plasmid pAP42].

Molecular cloning of genetic region of F-like plasmid pAP42, coding its surface exclusion system (system Six V) was performed. Restriction and genetic analysis of recombinant plasmids showed that six V locus is situated in Sal I-fragment f5 (4.2 MD) of this plasmid.

[Mutations of the genetic region Fin of the F-like plasmid pAP18-1].

With help of nitrosoguanidine 60 mutants of F-like plasmids pAP18-1 drd::Tn 5 and pAP18-1::Tn 9 were induced which determined resistance of E. coli cells of specific phage MS2. Mutational changes in fin-locus of those plasmids were accompanied by phenotypic reversion Fin(-)-Fin+.

[The role of host cells in the genetic regulation of plasmid transfer in Escherichia coli].

The role of serologically typed and nontyped E. coli cells in the expression of genetic regulation systems activity for repressed plasmids transfer (types fin OP, fin U, fin V) was studied. It is shown that the inhibiting action of such plasmids on the tra-genes functions of derepressed plasmids is more expressed in the cells of serologically nontyped E.

[Clinical picture and early diagnosis of craniospinal tumors].

The authors analyzed 32 cases of verified craniospinal tumors (CST) which were observed at a neurosurgical department over the last decade. These tumors were subdivided into neurinomas (n = 14), meningiomas (n = 11) and gliomas (n = 7). All patients underwent surgery.