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41.
Elizabeth R. Fielding David B. Archer Everly Conway de Macario Alberto J. L. Macario 《Applied microbiology》1988,54(3):835-836
Methanogenic bacteria were isolated from landfill sites in the United Kingdom. Strains of Methanobacterium formicicum, Methanosarcina barkeri, several different immunotypes of Methanobacterium bryantii, and a coccoid methanogen distinct from the reference immunotypes were identified. 相似文献
42.
Ras oncogene mediated induction of a 92 kDa metalloproteinase; strong correlation with the malignant phenotype 总被引:11,自引:0,他引:11
M Ballin D E Gomez C C Sinha U P Thorgeirsson 《Biochemical and biophysical research communications》1988,154(3):832-838
We have previously demonstrated that activated ras oncogenes can induce the metastatic phenotype and type IV collagenolytic activity in NIH/3T3 cells (Thorgeirsson et al. Mol. Cell. Biol. 5:259-262, 1985). The present study demonstrates ras-mediated induction of a 92 kDa metalloproteinase, which degrades gelatin and type IV collagen. Association of the 92 kDa proteinase expression with the malignant phenotype was also observed in human tumor cell lines. Our data indicate that the 92 kDa gelatin-collagen IV degrading metalloproteinase is an important participant in the proteolytic process involving tumor cell invasion and metastasis. 相似文献
43.
Daughter cells of the chlorococcal algaScenedesmus quadricauda incubated under photosynthesizing conditions in a nitrogen-free medium did not make any progress in the cell cycle. Photosynthetic
starch formation continued for a period corresponding to a half of the cell cycle and then levelled off. Protein synthesis
was very slow and it did not surpass double the initial amount. RNA content decayed from the start of treatment and approached
about 2 pg/cell.
When a synchronous population was deprived of nitrogen or of light in the middle of the cell cycle RNA synthesis stopped immediately
or very soon afterwards and, in spite ofabundant intracellular nitrogen reserves, RNA content slowly declined. This degradation
was much extensive in nitrogen starved cells where, eventually, the RNA content attained about half the starting value. In
both experimental variants, DNA replications started at the same time as in control culture, but the final amount of DNA attained
only half the control value. Protein synthesis stopped immediately in the dark. In the nitrogen-starved cells, it continued
for several hours and protein content increased about 70 % of the amount present at the start of starvation. The number of
daughter cells formed was proportional to the final protein content in the nitrogen-and light-deprived cells (corresponding
division numbers were 6 and 4, respectively). Upon refeeding of daughter cells formed under nitrogen starvation, RNA synthesis
started immediately, while protein synthesis displayed a lag of about 5 h. DNA replications were triggered at the time when
the ratio of RNA to DNA content attained the same value as in the control culture. 相似文献
44.
Summary A simple device is described for con-trolled feeding of pasty materials in laboratory scale fed-batch cultures. The device
was tested with apple pomace as raw material for production of microbial biomass, using the level of dissolved oxygen as controlled
parameter. 相似文献
45.
Dr. Alfonso Ruiz-Bravo María Jimenez-Valera Gerardo Alvarez de Cienfuegos Khalil Kouwatli Alberto Ramos-Cormenzana 《Current microbiology》1986,13(6):313-316
Twelve strains ofYersinia enterocolitica were examined for their ability to bind spontaneously to murine leukocytes. Each of eight HeLa cell invasive strains exhibited nonselective binding to peritoneal leukocytes, lymph node leukocytes, and thymocytes, whereas four noninvasive strains lacked binding properties. Like the HeLa cell invasion, the binding ofY. enterocolitica to leukocytes was much less efficient for bacteria grown at 37°C than for bacteria grown at 22°C. The binding properties were not influenced by the virulence plasmid that codes for Vwa+ phenotype. This leukocyte binding test is proposed as a simple assay for invasive properties ofY. enterocolitica. 相似文献
46.
Jorgina Satrustegui Juan Bautista Alberto Machado 《Molecular and cellular biochemistry》1983,51(2):123-127
Summary The utilization by yeast of two carbon sources is carried out through the operation of the glyoxylic acid cycle. Kinetic data from the isocitrate transforming enzymes suggest that the flow of isocitrate through the glyoxylic acid cycle depends upon the inhibition of the isocitrate decarboxylating enzymes. Both isocitrate dehydrogenases are inhibited by a mixture of glyoxylate + oxaloacetate, but for the reasons described in the text we consider that this inhibition is of no physiological significance. On the other hand, we have found that NADPH is a competitive inhibitor of NADP-isocitrate dehydrogenase with respect to NADP+, with a KI similar to its KM. It also produces an additive effect on the NADH-produced inhibition of NAD-isocitrate dehydrogenase. We propose NADPH as the compound that channels the utilization of isocitrate into the glyoxylic acid cycle. This is supported by the finding of an increased NADPH/NADP+ ratio in acetate grown yeast with respect to glucose grown cells. 相似文献
47.
Ana Rosa Santa Cruza Luis A. Quesada Allue Alberto Baldi 《Molecular and cellular biochemistry》1983,56(1):55-66
Microsomal preparations from malignant human breast tumors catalyzed the transfer of mannose and glucose from GDP-[14C]-Man and UDP-[14C]-Glc into lipid-linked sugars and glycoprotein-like substances. As judged by several criteria the obtained lipid-linked monosaccharides behaved as dolichyl phosphate mannose and dolichyl phosphate glucose whereas lipid-linked oligosaccharides behaved as polyprenyl diphosphate derivatives. The optimum conditions for mannosyl- and glucosyl-transfer reactions and the effect of dolichyl phosphate, detergent and EDTA on incubation mixture were described. 相似文献
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