Specificity of introducing the transposon that determines chloramphenicol resistance (Tn9) into the chromosome of Escherichia coli K-12]

Translocation of Tn9 coding for chloramphenicol-resistance from lambdaatt80 genome into bacterial chromosome was studied. Three preferential sites of Tn9 integration, attTn9A, ATTTn9B and attTn9C, were found on the chromosome of Escherichia coli K-12; attTn9A was mapped between purD and rpoB loci, attTn9B was cotransducible with argG, attTn9C was located between 61 and 66 minutes of the standard E. coli K-12 genetic map. The integration of Tn9 in these att sites occurs with almost equal probability. Tn9 integrated in attTn9A shown significantly higher frequency of excision and P1-transduction frequency than Tn9 integrated in either of two other attTn9 sites.     

Rhythmical contractile activity of amnion in embryogenesis of reptiles and birds

Rhythmical contractile activity of amnion accompanies development of reptiles and birds in the course of a large part of embryogenesis. These rhythmical contractions are myogenic and spontaneous. The strength, frequency, and character of the amnion contractions change in embryogenesis in a regular way. This type of rhythmical activity is sensitive to many neurotransmitters and external factors. Features of similarity and difference of the amnion rhythmical contractile activity in the reptile and bird embryogenesis are considered. There are discussed a possible functional significance of this rhythmical activity and its participation in response of embryo to external actions, such as temperature fluctuations and acute hypoxia.     

Use of the toxin-tissue receptor reaction for detecting toxic substances of the causative agents of acute intestinal diseases

The possibility of using erythrocytic ganglioside diagnostic reagents (EGDR) for the detection of V. cholerae, E. coli and S. typhimurium enterotoxins in the passive hemagglutination (PHA) test has been shown. Museum strains and cultures isolated from patients with acute intestinal diseases were tested for the presence of enterotoxins. Cell-free extracts were studied by biological methods and by serological titration in the PHA test with the use of EGDR. The diagnostic reagent was found to interact only with those enterotoxins whose specific receptors were gangliosides GM1.     

Elimination of quinones from aqueous environments by phenols and the effect of their mixtures on the luminescence of Beneckea harveyi bacteria

In the mixture of hydroquinone with other phenols the content of quinones has been measured by potentiometrical and polarographical methods. The decrease of quinone content in the mixture in comparison with the pure solution has been noted. The toxicity of solution estimated according to extinction of luminescence of bacteria at adding other phenols decreases.     

Approximately hourly rhythm of 3',5'-cAMP in rat parotid gland slices]

3',5'-CAMP concentration in rat parotid gland slices indubated in vitro for 12-14 hours was measured by radioimmunoassay. Clices for determination of cyclic nucleotide concentrations were taken at 10-minute intervals over a period of 2 hours. All slices used in a specific experiment originated from a single gland. Rhythmic changes in 3',5'-cAMP concentration in the rat parotid gland were found. The period of these changes (20-50 min) was similar to that of fluctuations in other parameters, such as dry weight, the rate of protein synthesis and ornithine decarboxylase activity, described for the same system elsewhere.