Characteristics of Pseudomonas putida plasmid DNAs

Physico-chemical characteristics of plasmid DNAs isoalted from Pseudomonas putida G7 were studied as well as the behavior of these DNAs in th eourse of chromatography on columns with Sepharose 4B and kieselguhr with methylated albumin (MAC). This strain was found to contain several plasmid DNAs having molecular weights of 33-36X10(6), 15-18X10(6), and 3-5X10(6) dalton. The plasmid DNAs of biodegradation are supposed to be located in the vicinity of chromosomes, and only a small part of them is characterized by extrachromosomal localization.     

Mycobacterium tuberculosis ClpP1 and ClpP2 Function Together in Protein Degradation and Are Required for Viability in vitro and During Infection

In most bacteria, Clp protease is a conserved, non-essential serine protease that regulates the response to various stresses. Mycobacteria, including Mycobacterium tuberculosis (Mtb) and Mycobacterium smegmatis, unlike most well studied prokaryotes, encode two ClpP homologs, ClpP1 and ClpP2, in a single operon. Here we demonstrate that the two proteins form a mixed complex (ClpP1P2) in mycobacteria. Using two different approaches, promoter replacement, and a novel system of inducible protein degradation, leading to inducible expression of clpP1 and clpP2, we demonstrate that both genes are essential for growth and that a marked depletion of either one results in rapid bacterial death. ClpP1P2 protease appears important in degrading missense and prematurely terminated peptides, as partial depletion of ClpP2 reduced growth specifically in the presence of antibiotics that increase errors in translation. We further show that the ClpP1P2 protease is required for the degradation of proteins tagged with the SsrA motif, a tag co-translationally added to incomplete protein products. Using active site mutants of ClpP1 and ClpP2, we show that the activity of each subunit is required for proteolysis, for normal growth of Mtb in vitro and during infection of mice. These observations suggest that the Clp protease plays an unusual and essential role in Mtb and may serve as an ideal target for antimycobacterial therapy.     

Dopamine modification of the Ca-component of the action potential in the neuron soma of the mollusk L. stagnalis

Dopamine has been found to decrease reversibly the action potential rising phase in identified L. stagnalis neurones. Using voltage-clamp and intracellular dialysis techniques it is shown that dopamine inhibits electroexcitable Ca-current, and changes in Ca-current determine those in the action potential shape. Serotonin and adrenaline influence the Ca-current in a similar way as dopamine does. Inhibition of Ca-conductance is found not to be related to possible effect of these neuromediators on intracellular level of free Ca ions or cyclic AMP.     

The differentiation of rhythmogenic characteristics of the ureter's different regions in guinea pigs

Characteristics of rhythmogenic pacemakers of the ureter's perirenal middle and peribladder region morphologically and electrophysiologically are analysed in guinea pigs both in presence of spreading activity and breach of conductivity. It was shown that the action potential's amplitude of the middle region is the highest and duration of the spike activities from perirenal zone is maximal and all three regions are characterised by different functional conditions.