[Cytomorphological and cultural characteristics of tylosin-producing strains with different antibiotic activity]. / Tsitomorfologicheskie i kul'tural'nye kharakteristiki shtammov-produtsentov tilozina s razlichnoi antibioticheskoi aktivnost'iu.

Cytomorphological and cultural characteristics of highly and low active collection strains of Streptomyces fradiae producing tylosin were studied. The strains were grown on agarized and liquid media. It was shown that unlike the low active strain, the highly active one was less sporogenic, the difference being more pronounced when tylosin was added to the agarized medium. When the strains were grown in the fermentation medium there were detected differences between them in the growth type and microcolony structure at the early stages of the fermentation process. During intensive synthesis of tylosin spheric structures were found to form near the hyphal surfaces. The phenomenon was previously observed in cultures producing other antibiotics. In the low active strain the structures were single while in the highly active strain they formed in large numbers.

[Membrane potential levels in Acetabularia cells]. / Urovni membrannogo potentsiala u kletki atsetabuliarii

The membrane potential (MP) of A. mediterranea cell is shown to have two stationary levels RP==--170 mv and EP=--80 mV and an unstable one -- level of action potential peaks -- EP=--60 mV. The following transitions between the MP levels are possible: RP leads to EP' equilibrium EP leads to RP. The transition RP leads to EP' always has an exponential region. Values of the MP levels and the time constant of RP leads to EP' transition are equal in spontaneous AP, in AP induced by switching off the light or current pulse, when the cell is treated with 10(-3) M solution of DNP and when a part of cell is amputated. It is suggested that RP leads to EP' transition takes place when the electrogenic Cl-pump is switched off, while EP leads to RP when it is switched on.

[Electric parameters and equivalent schematics for Acetabularia cells]. / Elektricheskie parametry i ékvivalentnaia skhema kletki atsetabuliarii

Was measured values of electric resistance (R) and capacity (C) of A. mediterranea cell at different levels of the membrane potential (MP). At the level -170 mV, RRP=4,3 KOm-cm2, at the level -80 mV REP=1,4 KOm-cm2. At both levels of MP C congruent to 1,3-10(3) mkF/cm2. A variant of equivalent electric scheme of the cell is suggested. Values of the elements comprising the scheme are presented, which allow an approximate reproduction of the value of MP levels and of transient processes between them.