Phenotypic features of a strain of Yersinia pseudotuberculosis with the pVM82 plasmid, detected at pseudotuberculosis outbreak foci]

The phenotypic properties conferred to Yersinia pseudotuberculosis cells by the genetical determinants of a 25Md fragment of the plasmid pVM82 coding for the modified cellular immune response in the infected organism. The fragment was shown to determine the conjugative properties of the plasmid, the resistance of bacterial cells to a number of hydrophobic agents and cellular ability to absorb the Congo red dye. The latter confirms the presence of additional structural components in the cell wall of the strain harbouring the plasmid pVM82. The increased resistance of the plasmid-containing strain to bactericidal effect of the blood plasma was demonstrated as compared with the resistance of the strains harbouring the p57 plasmid lacking the 25Md fragment or no plasmid at all.     

Effects of spaceflight on the proliferation of jejunal mucosal cells

The mitotic indices, villus heights, and crypt depths were determined in each of three jejunal regions (proximal, middle, and distal) for five animals each in the flight, vivarium, and synchronous groups. Because of the rapid turnover of intestinal mucosal cells and the delay in recovering the flight animals, it is not known whether the proliferation of jejunal mucosal cells is affected by microgravity conditions associated with spaceflight. However, since there were no consistent differences between animals in the flight group and those in the synchronous and vivarium control groups, it appears that any effects of microgravity on the turnover of jejunal mucosal cells are short-lived. Thus, this study represents an initial step in determining the effects of microgravity on the proliferation and turnover of intestinal mucosal cells.     

Characteristics of the het mutations in the Escherichia coli chromosome causing an increase in Tn1 transposition frequency

Four mutations were studied which lead to increasing the frequency of transposon Tn1 translocation into different replicons. These mutations (het1, het2, het3 and het4) increase the frequency of Tn1 translocation 10-20-fold. The het1 mutation is recessive and has been localized in the 90-94.5 min region of the bacterial chromosome. The mutation effects Tn1 transposition in the presence of F plasmid only. As we have demonstrated recently, F-plasmid inhibits Tn1 transposition in Escherichia coli cells. The het1 mutation eliminates this inhibition. Unlike het2, het3 and het4 mutations, het1 is responsible for resistance to male phages f1, f2, MS2 and inhibition of conjugative transfer in F+ bacteria.     

Study of the relationship between the trace element content and the physiological properties of Salmonella typhi during submerged cultivation

The content of trace elements in the cells served as one of the characteristics of physiological condition of the population. The character of the changes in the trace elements content depending on the rate of the microbial multiplication pointed to the importance of the mineral sources of nutrition for the development of the cells analyzed.     

Isolation of estrophilic fractions of hydroxysteroid dehydrogenase from rabbit liver

Estrophilic forms of rabbit liver cytosolic hydroxysteroid-dehydrogenase (HSD) were obtained as a highly purified preparations by means of fractionation with ammonium sulfate, gel-filtration, ion-exchange chromatography on DEAE-Sephadex A-50, affinity chromatography on estradiol-Sepharose and ion-exchange chromatography on DEAE-Toyopearl 650M. The protein express 4 different kinds of NADP-dependent activities: 3 alpha, 3 beta- and 17 beta-HSD activities with androgens and 20 alpha-HSD with progesterone as substrates. Revealed multiplicity of HSD enzymatic activity is demonstrated here for the first time. 17 beta-HSD activity of the protein preparations with estradiol is extremely low. Absence of a real metabolic activity of the protein with a ligand interacting with it rather intensively suggests that the isolated HSD forms can act not only as an enzyme, but also as a buffer-reserving mechanism for some steroids.     

Partial characterization of protein kinase-catalyzed phosphorylation of low molecular weight proteins in purified preparations of pigeon heart sarcolemma and sarcoplasmic reticulum

Pigeon heart microsomes contain three minor size protein kinase substrates of minimal molecular weights of 22 000, 15 000, and 11 500, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When the microsomes were partially loaded with calcium oxalate and subjected to rate zonal and isopynic centrifugations in sucrose density gradient columns, the 22 000 and the 15 000 dalton proteins settled in the heaviest fraction, which was composed mainly of vesicles of sarcoplasmic reticular membranes; the 11 500 dalton protein was concentrated in the lightest fractions, which consisted chiefly of vesicles of sarcolemmal origin. During incubation of the membrane fractions with Mg[γ-³²P]ATP significant amounts of ³²P were incorporated into all these proteins. Incorporation of ³²P into the 15 000 dalton protein was moderately and ³²P incorporation into the 22 000 dalton protein was markedly enhanced in the presence of exogenous soluble cyclic AMP-dependent protein kinase and cyclic AMP. The phosphorylation of the three proteins was virtually unaffected by CA²⁺ concentrations up to 0.1 mM and by ethyleneglycol-bis(β-aminoethylether)-N,N′-tetraacetic acid in the absence of added Ca²⁺.Phosphorylation of the 22 000 and the 11 500 dalton proteins occurred mainly at serine residues. In the 15 000 dalton protein threonine residues were the main site of endogenous phosphorylation. Nearly equal amounts of [³²P]-phosphate were incorporated into threonine and serine residues of this protein when phosphorylation was supported by exogenous cyclic AMP-dependent protein kinase and cyclic AMP.The 15 000 dalton protein could be removed from its membrane attachment by extraction with an acidic chloroform/methanol mixture. This step opens the way for the purification of this membrane-bound protein kinase substrate.     

Inhibition of cyclic nucleotide phosphodiesterase from the rod outer segments of the frog retina by 3-hydroxypyridine

The influence of 8 analogues of 3-hydroxypyridine upon the phosphodiesterase of rod outer segments of frog retinae has been investigated. It has been shown that the analogues of 3-hydroxypyridine inhibit the enzeme reversely and noncompetitively in case of hydrolysis towards the cAMP and cGMP. The natural analogues of 3-hydroxypyridine (pyridoxol, pyridoxale, pyridoxale-phosphate) do not exert the inhibiting effect. It is suggested that the inhibition of phosphodiesterase from rod outer segments of retinae is caused by the interaction of 3-hydroxypyridines with the hydrophobic microenvironment of the active site of the enzyme.