Reclustering of scattered Golgi elements occurs along microtubules

Depolymerization of the interphase microtubules by nocodazole results in the scattering and apparent fragmentation of the Golgi apparatus in Vero fibroblast cells. Upon removal of the drug, the interphase microtubules repolymerize, and the scattered Golgi elements move back to the region around the microtubule-organizing center (MTOC) within 40 to 60 min. Using a fluorescent lipid analogue (C6-NBD-ceramide) as a vital stain for the scattered Golgi elements, their relocation was visualized by video-enhanced fluorescence microscopy in Vero cells maintained at 20 degrees C. The NBD-labeled structures were identified as Golgi elements by their colocalization with galactosyltransferase in the fixed cells. During reclustering, NBD-labeled Golgi elements were observed to move by discontinuous saltations towards the MTOC with velocities of 0.1 to 0.4 micron/s. Paths along which Golgi elements moved were super-imposable on microtubules visualized by indirect immunofluorescence. Neither the collapse of intermediate filaments caused by microinjection of antibodies to vimentin nor the disruption of microfilaments by cytochalasin D had an effect on the reclustering of Golgi elements or the positioning of the Golgi apparatus. These data show that scattered Golgi elements move along microtubules back to the region around the MTOC, while neither intact intermediate filaments nor microfilaments are involved.     

Correction of lipid peroxidation in stress with the peptide bioregulator thymopentin

Experiments on rats subjected to acute stress have revealed protective effect of thymopentin pentapeptide on somatic disorders and the state of the antioxidation system and the processes of lipid peroxidation in blood and brain.     

Lactate dehydrogenase-induced conformational changes of F-actin in myosin-free ghost single fibres

The changes in conformation of F-actin induced by the binding of the glycolytic enzyme lactate dehydrogenase were studied in myosin-free single ghost muscle fibres. The formation of the lactate dehydrogenase-F-actin complex was accompanied by changes in the parameters of intrinsic (tryptophan) and extrinsic (rhodaminyl-phalloin) polarized fluorescence of ghost muscle fibre F-actin. Lactate dehydrogenase stimulated actin-activated Mg2+-ATPase of myosin subfragment 1 by 30%. F-actin of ghost fibres depressed lactate dehydrogenase activity to 20% of the initial values. It is suggested that the energy-providing mechanism is coupled with that of muscle contraction through conformational changes in F-actin.     

Comparison of antibiotic complexes formed by cultures of Streptomyces griseoruber

Physico-chemical properties of antibiotic complexes formed by various strains of Streptomyces griseoruber: VNIIA 1195, VNIIA 1193-INA 2022/55 and IMiV 1618 were compared. It was shown that the antibiotic complex 1195 differed by the electron absorption spectrum, chromatographic mobility and indicator properties from lateriomycins A and B produced by the type culture of S. griseoruber, Jamaguchi et Saburi, 1955 and strain 70717, as well as from prodigiozin produced by S. griseoruber, VNIIA 1193. By the absorption spectra and chromatographic mobility the components of the antibiotic complex 1195 were identical with cinerubins A and B, pyrromycin and eta- and xi-pyrromycinones included in the composition of antibiotic 1618 produced by S. griseoruber 1618 and differed in their quantitative contents and absence of epsilon-pyrromycinones.     

Relation of bacitracin synthesis and manganese content in Bacillus licheniformis: antibiotic production in colonies forming on media with high levels of Mn2+

Population of B. licheniformis is not homogeneous with respect to its sensitivity to Mn2+. Active bacitracin producing cultures with high and low sensitivity to exogenic manganese are described. In media containing high sublethal concentrations of Mn2+ there were detected two types of bacitracin-producing colonies i.e. light and dark differing likely in the mechanisms of their cell protection from the metal excess. Since bacitracin production did not always correlate with sensitivity to Mn2+ at the level of the colony formation the use of Mn2+ as a selective factor for isolating inactive strains of B. licheniformis is of low efficiency.     

Crystal structure of thermitase from Thermoactinomyces vulgaris at 2.2 A resolution

The crystal structure of thermitase from Thermoactinomyces vulgaris has been determined by x-ray diffraction at 2.2 A resolution. The structure was solved by a combination of single isomorphous replacement and molecular replacement methods. The structure was refined to a conventional R factor of 0.24 using restrained least square procedures CORELS and PROLSQ. The tertiary structure of thermitase is similar to that of subtilsin BPN'. The greatest differences between these structures are related to the insertions and deletions in the sequence.     

Extrachromosomal Elements Cause a Reduced Division Potential in Nib 1 Strains of Saccharomyces Cerevisiae

The nib 1 allele of yeast confers a sensitivity to an endogenous plasmid, 2 mu DNA, in that nib 1 strains bearing 2 mu DNA (cir+) exhibit a reduction in division potential. In the present study, the reduction in division potential characteristic of nib 1 cir+ strains is shown to be dependent on the simultaneous presence of both the A and the D open reading frames of 2 mu DNA as well as on the presence of an unidentified extrachromosomal element other than 2 mu DNA. Furthermore, in nib 1 strains, an uncharacterized extrachromosomal element can cause a less severe reduction of division potential in the absence of intact 2 mu DNA. Thus, the nib 1 allele may confer a generalized sensitivity to extrachromosomal elements.     

Combined reaction of the lymphoid organs and the adrenals to stress in mature animals subjected to cold in the early period of postnatal ontogeny

Structural-functional organization of the lymphoid organs and functional state of the adrenals have been studied in animals, subjected to cold in early postnatal period, as well as changes of the parameters mentioned to a short and prolonged cooling in mature rats. For the animals increase in the thymus mass and in reproduction rate of lymphocytes in the thymus, spleen and lymph nodes is specific against the background of high corticosteroid secretion. When the control animals are kept in cold for a long time, after the phase of an acute stress, accompanied with hypercorticism and a pronounced lymphatic effect, during the period of an increased cold stability, the high secretion of glucocorticoid hormones is accompanied with a certain activation of thymus-dependent zones in the peripheral lymphoid organs. In the mature rats, subjected to cold at early ontogenesis both stress-reaction to cooling and rearrangement in the regulatory systems studied does not develop at adaptation to cold.     

Interaction between D-glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase labeled by fluorescein-5'-isothiocyanate: evidence that the dye participates in the interaction

An interaction of rabbit muscle D-glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase labeled with FITC was studied by following the changes in fluorescence intensity of the bound dye. The association between the two enzymes was found to be a rather slow process characterized by a second order rate constant of 1.1 +/- 0.2.10(3) M-1 s-1, the KD of the complex between apoenzymes being 3.2.10(-7) M. The stability of the complex increased upon increase of temperature and ionic strength of the medium, suggesting a hydrophobic character of association. The ligands which bind at the active centers of the two enzymes (NAD+, ATP, 3-phosphoglycerate) weakened the bienzyme association. Unlabeled 3-phosphoglycerate kinase was unable to displace the FITC-labeled enzyme from the complex. Taken together, the results indicate that interaction between D-glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase labeled by FITC is assisted by the dye, which may bind at nucleotide-binding sites of GPDH. No interaction was observed between the FITC-labeled 3-phosphoglycerate kinase and lactate dehydrogenase, which suggests that protein-protein interaction at specific "recognition" sites may be a prerequisite for the complex formation.     

Metabolism of thromboxane B2 in the isolated perfused rat kidney: mass spectrometric identification of urinary products

The metabolism of thromboxane B2 (TXB2), the stable breakdown product of thromboxane A2, has been studied in isolated perfused kidney preparations using a recirculating system. In a first experiment, TXB2 was infused at a rate of 20 micrograms/kg per min. In a second experiment, a 1:1 mixture of TXB2 and octadeuterated TXB2 (0.4 microgram/kg per min each) was infused. Urinary samples collected during the infusion of TXB2 or vehicle were extracted on C18 cartridges and derivatized to methyl or pentafluorobenzyl ester, methyloxime, trimethylsilyl ether. Samples were analyzed by high-resolution gas chromatography-mass spectrometry in the electron impact and negative ion chemical ionization modes. Products of beta-oxidation, reduction of the delta 5,6 double bond and dehydrogenation at C-11 (2,3-dinor-TXB2, 2,3-dinor-TXB1, 2,3,4,5-tetranor-TXB1 and 11-dehydro-TXB2) were identified in addition to unmetabolized TXB2. 2,3,4,5-tetranor-TXB1 and 2,3-dinor-TXB1 were the most abundant metabolites.