RESUMO
Structural peculiarities of SCP2 plasmid isolated from different derivatives of Streptomyces coelicolor A3(2) were studied. By means of heteroduplexing 800 b.p. DNA insertion in SCP2 plasmid of S18-1 derivative was detected. The position of this insertion was localised on the SCP2 restriction map. A transposon-like structure with similar characteristics was detected and localised in different variants of SCP2 plasmid. This 600 bp DNA region is flanked by 20 bp inverted repeats and has the single EcoRI cleavage site. It is noted that the stretching of single-strand DNA circles of SCP2 plasmid was significantly less than that of single-strand DNA circles of pBR322 and PAS3; Tn9 plasmids. This may likely depend on the GC content of different plasmids.
Assuntos
Plasmídeos , Streptomyces/genética , Composição de Bases , Enzimas de Restrição do DNA , DNA Bacteriano/genética , DNA de Cadeia Simples/genética , Variação Genética , Microscopia Eletrônica , Conformação de Ácido NucleicoRESUMO
The radioreceptor method was used to find high affinity, saturable and partially reversible specific binding of 3H-5HT with a gross membrane fraction of human peripheral blood lymphocytes. The Sketchard analysis demonstrated the presence of two types of the binding sites with equilibrium dissociation constants 2 nM and 66 nM. These characteristics are similar to those of 3H-5HT binding with the brain receptors. The results obtained suggest the existence on human lymphocytes of two types of serotonin receptors.