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The physical properties of human platelet myosin in crude extracts were studied by means of Sepharose 4B gel filtration and sucrose density gradient centrifugation in the presence or absence of Mg-ATP. Platelet myosin extracted with a buffer containing 0-0.15 M KCl gave a Stokes radius of about 12.0-12.5 nm irrespective of the presence or absence of Mg-ATP. The sedimentation coefficients obtained in the presence of Mg-ATP were about 10-11 and 8.5S at 0.05-0.10 and 0.15 M KCl, respectively, whereas the values obtained in the absence of Mg-ATP were about 16, 9-12, and 8.5S at 0.05, 0.10, and 0.15 M KCl, respectively. The apparent molecular weight in the presence of Mg-ATP, therefore, was about 500,000 and 420,000 at 0.05-0.10 and 0.15 M KCl, respectively, while the molecular weight in the absence of Mg-ATP was about 790,000, 460,000-620,000, and 440,000 at 0.05, 0.10, and 0.15 M KCl, respectively. The purified monomeric platelet myosin that had been solubilized with Mg-ATP at 0.10 M KCl had a Stokes radius of about 12.5 nm, a sedimentation coefficient of about 9S, and an apparent molecular weight of 460,000. On the other hand, while crude platelet myosin extracted at 0.6 M KCl with Mg-ATP gave a Stokes radius of about 20 nm, a sedimentation coefficient of about of 6S, and an apparent molecular weight of about 490,000, each of these physical parameters obtained in the absence of Mg-ATP was much larger than that obtained in the presence of Mg-ATP because the myosin was associated with F-actin.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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Aldehyde reductases from several mammalian and avian tissues transferred the pro-4R hydrogen of NADPH to the substrate, whereas the stereospecificity of carbonyl reductases was not uniform being correlated with the ability to catalyze the oxidoreduction of hydroxysteroids.  相似文献   
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Heterosexual chimerism among singleton females produced by multiple nonsexed embryo transfer (MNET singleton females) was investigated using chromosome typing and PCR (polymerase chain reaction)-amplification of male-specific DNA (msDNA). Of the 22 animals tested, 21 were classified as normal by both methods (i.e., showing no male cells among 100 metaphase spreads in chromosome typing and being msDNA negative in PCR). No morphological abnormalities of the genital organs were observed among 19 MNET single females. One MNET singleton female was, however, classified as a freemartin by PCR (male-specific DNA positive), but it was classified as normal cytogenetically. This individual probably had a low degree of heterosexual chimerism, and it seems that the chimerism derived from MNET was difficult to diagnose by chromosome typing, although it was detectable by PCR. The genital organs of this individual (15-mo-old Aberdeen Angus) were normal in form (both external and internal) and size. However, a very small structure, resembling seminiferous tubule, was found in the left ovary. It may be concluded that most MNET singleton females are expected to have normal reproductive function.  相似文献   
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To explore the possibility that cyclic nucleotides control green algal growth and division, Chlamydomonas chemostat cultures were assayed for cyclic nucleotides. Substantial qualities of cAMP were found in cells and in extracellular millieu. Most cGMP molecules were extracellular. Slowing cell growth by slowing chemostat dilution caused reversible changes in cellular morphology and cyclic nucleotide levels. During slowed growth cAMP level increased dramatically; cGMP level decreased. New cells resulting from division were not released from original cell wall.  相似文献   
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With specific monoclonal antibodies, we found that human endometrial stromal cells and decidual cells express two function-related surface antigens. Indirect immunofluorescence staining revealed that both endometrial stromal cells and decidual cells during the first trimester of pregnancy expressed cluster of differentiation (CD) 13 antigen and CD10 antigen, which are identical to aminopeptidase N and neutral endopeptidase, respectively. By flow cytometric analysis, CD13 antigen was detected on 82-93% of the examined cells, and CD10 antigen was detected on 75-93% of the examined cells in endometrial stromal cell-enriched preparations. Furthermore, peptidase activity was detected in these cell preparations by an assay based on the hydrolysis of alanine-p-nitroanilide into p-nitroaniline and alanine.  相似文献   
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Respiration-deficient mutants (Rho-, petite) of Saccharomyces carlsbergensis were obtained by treatment with trypaflavin (euflavine). Dried cells of these mutants phosphorylated mononucleotides to their triphosphates and further formed not only cytidine 5'-diphosphate-choline, but also sugar nucleotides, such as uridine 5'-diphosphate-glucose, guanosine 5'-diphosphate-mannose, etc. The activities were the same or slightly greater than those of the wild strain. These results showed that energy (adenosine 5'-triphosphate) necessary for phosphorylation of mononucleotides was sufficiently supplied by the glycolysis system.  相似文献   
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Previously we reported that, lactic acid bacteria (LAB) can induce human dermal fibroblast (HDF) cells to form multipotent cell clusters which are able to transdifferentiate into three germ layer derived cell lineages. Later on, we confirmed that ribosome is responsible for the LAB-induced transdifferentiation and ribosomes from diverse organisms can mimic the LAB effect on HDF cells. In our present study we have shown that, upon incorporation of ribosomes, non-small cell lung cancer cell line A549 and gastric tubular adenocarcinoma cell line H-111-TC are transformed into spheroid like morphology those can be transdifferentiated into adipocytes and osteoblast. Our qPCR analysis has revealed that, during the formation of ribosome induced cancer cell spheroids, the expression of the cancer cell associated markers and cell cycle/proliferation markers were altered at different time point. Through our investigation, here we report a novel and a non-invasive approach for cancer cell reprogramming by incorporating ribosomes.  相似文献   
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