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91.
Effective oxygen diffusion coefficients and solubilities were measured for submerged cultures of Saccharomyces cerevisiae, Escherichia coli, and Penicillium chrysogenum. Both effective oxygen diffusion coefficients and solubilities were found to decrease with increasing cell concentrations in the fermentation media. Comparison of the experimental results of effective oxygen diffusion coefficients in fermentation media with values theoretically predicted on the assumption of unpenetrable microbial cells indicates that oxygen molecules diffuse through the cells during the diffusion process. Within the cell concentration range of typical submerged fermentations, the effective oxygen diffusion coefficient of the fermentation media can be described as D(e) = A(1)f + A(2)f(2). In this equation, fis the cell volume fraction and both A(1) and A(2) are functions of the shape of the cells and the ratio of effective oxygen diffusion coefficient in microbial cells to that in the medium. 相似文献
92.
This paper describes usefulness of the ultrasonographical device (USD) for the diagnosis of pregnancy and the observation of fetal growth in the squirrel monkeys (Saimiri sciureus) conceived under group breeding conditions. Pregnancy was diagnosed on the basis of the detection of gestational sac (GS) in the uterus. The GS was first detected 127 +/- 10 days before delivery. The heart beat of embryo was detected around 114 days before delivery. It was able to judge conditions of fetal growth by measuring the size of GS and the biparietal diameter. No difference in uterine size between nonpregnant and pregnant animals was observed 135 days before delivery. 相似文献
93.
A K Ho T P Thomas C L Chik W B Anderson D C Klein 《The Journal of biological chemistry》1988,263(19):9292-9297
Phenylephrine is known to stimulate translocation of protein kinase C in rat pinealocytes (Sugden, D., Vanecek, J., Klein, D.C., Thomas, T.P., and Anderson, W. B. (1985) Nature 314, 359-361). In the present study, the receptor mediating this effect was found to belong to the alpha 1-adrenoceptor subclass. Activation of this receptor is also known to produce a sustained increase in [Ca2+]i by increasing net influx (Sugden, A. L., Sugden, D., and Klein, D. C. (1985) J. Biol. Chem. 261, 11608-11612), which points to the possible importance of Ca2+ influx in the subcellular redistribution (activation) of protein kinase C in intact cells. This possibility was investigated by reducing extracellular Ca2+ ((Ca2+]o) with EGTA or by inhibiting Ca2+ influx with inorganic Ca2+ blockers. These treatments reduced alpha 1-adrenoceptor-mediated translocation of protein kinase C. This suggested that elevation of Ca2+ influx alone triggers activation of protein kinase C. In support of this, it was found that treatments which elevate Ca2+ influx, including increased extracellular K+ and addition of the Ca2+ ionophore A23187, cause redistribution of protein kinase C. The effect of K+ was blocked by nifedipine and that of A23187 by EGTA, indicating that effects of these agents are Ca2+-dependent. The possible role of phospholipase C activation in these effects was examined by measuring the formation of [3H]diacylglycerol by cells labeled with [3H]arachidonic acid. Although [3H]diacylglycerol formation was easily detected in the presence or absence of an effective concentration of an inhibitor of diacylglycerol kinase, none of the agents which cause rapid translocation of protein kinase C were found to cause a rapid increase in the generation of [3H]diacylglycerol. These findings establish that an increase in Ca2+ influx is sufficient to trigger translocation of protein kinase C. In addition, we found that a very close correlation exists between translocation of protein kinase C by phenylephrine, K+, and A23187 and their ability to potentiate beta-adrenergic stimulation of cAMP and cGMP accumulation. This provides strong support to the proposal that translocation of protein kinase C is required for potentiation of beta-adrenergic stimulation of pinealocyte cAMP and cGMP accumulation. 相似文献
94.
Scanning electron microscopy (SEM) shows that the postcapillary high-endothelial venules of lymph nodes and Peyer's patches consist of two segments each with a different surface relief: a proximal segment with a cobblestone surface pattern and a distal segment of interlacing cytoplasmic plates. Both segments have deep adluminal crevices in which lymphocytes are lodged. The internal structural configuration of this endothelium has been examined by transmission electron microscopy (TEM) of serial sections of lymph nodes and Peyer's patches of mice, rats, and guinea pigs. The serial sections revealed that the endothelial cell bodies and their cytoplasmic extensions were disposed in a direction generally lateral to the luminal surface and intruded into the intercellular spaces of similarly disposed neighboring endothelial cells, resulting in a complex interlacing cellular pattern. Lymphocytes penetrated the endothelial cell body and secondarily followed an intracellular pathway through which they entered the extravascular compartment. At the exposed surfaces of the adluminal venule wall, recirculating lymphocytes were seen in SEM images to enter the endothelium by penetrating the endothelial cell body. The mode of migration of lymphocytes lodged in the endothelial crevices could be determined by SEM and has been examined by TEM of serial sections. At these locations as at the exposed surfaces, lymphocytes also entered the venule by penetrating the endothelial cell body. At both sites this transcellular pathway was followed by lymphocyte entry into the intercellular spaces from which they migrated into the extravascular compartment. 相似文献
95.
We have visualized the exocytosis of lysosomes into the peripheral circulation by the phagocytic endothelia of the venous sinuses of liver and bone marrow of rats. Perfusion fixation at normal body temperature produced images of the earliest stages of lysosomal exocytosis. After fixation at low body temperatures (7-12 degrees C), advanced stages of this process became evident, showing extrusion of lysosomes and their contents into the circulation. It is postulated that this form of exocytosis has escaped structural detection because of its rapidity and relative infrequency as compared to merocrine secretory exocytosis, and that fixation at low body temperatures arrests or slows down these exocytic events in sufficient measure for ultrastructural visualization. The possibility that this lysosomal exocytosis contributes to the presence of lysosomal enzymes detected in the peripheral blood should be considered. In addition, it is likely that lysosomal degradation products may be discharged by exocytosis into the circulation. 相似文献
96.
Mycological survey of Korean cereals and production of mycotoxins by Fusarium isolates. 总被引:2,自引:2,他引:0
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U S Lee H S Jang T Tanaka N Toyasaki Y Sugiura Y J Oh C M Cho Y Ueno 《Applied microbiology》1986,52(6):1258-1260
The fungal species isolated from Korean cereals (barley, polished barley, wheat, rye, and malt) were Alternaria spp., Aspergillus spp., Chaetomium spp., Drechslera spp., Epicoccum sp., Fusarium spp., and Penicillium spp., etc. The number of Fusarium strains isolated was 36, and their ability to produce Fusarium mycotoxins on rice was tested. Nivalenol (NIV) was produced by Fusarium graminearum (7 of 9 isolates), Fusarium oxysporum (3 of 10 isolates), and Fusarium spp. (7 of 15 isolates). Of 15 isolates of Fusarium spp., 6 formed deoxynivalenol (DON). Fusarenon-X and 3-acetyl-DON were produced by most NIV- and DON-forming isolates, respectively. Zearalenone was produced by 3 isolates of F. graminearum, 1 isolate of Fusarium equiseti, and 11 isolates of Fusarium spp. T-2 toxin was not produced by any Fusarium isolates. The highest concentrations of mycotoxins produced by Fusarium isolates were 77.4 (NIV), 5.3 (DON), 138.3 (fusarenon-X), 40.6 (3-acetyl-DON), and 23.2 (zearalenone) micrograms/g. 相似文献
97.
Nickel(II)-reconstituted hemoglobin (NiHb) and myoglobin (NiMb) and model Ni porphyrins have been investigated by Soret-resonance Raman difference spectroscopy. Two sets of frequencies for the oxidation-state and core-size marker lines in the region from 1300 to 1700 cm-1 indicate two distinct sites in NiHb. Only one of these sites is evident in the Raman spectra of NiMb. This result is consistent with the UV-visible absorption spectrum of NiHb, which shows two Soret bands at 397 and 420 nm and one Soret at 424 nm for NiMb. Excitation at the blue Soret component of NiHb with 406.7-nm laser radiation preferentially enhances the set of Raman marker lines typical of Ni-protoporphyrin IX [Ni(ProtoP )] in noncoordinating solvents. The wavelength of the blue Soret component and the Raman spectrum indicate four-coordination for this site in NiHb. Laser excitation in the red Soret band enhances a set of lines whose frequencies are compatible with neither four- nor six-coordinate frequencies but are intermediate between the two. The red Soret band of the proteins is also considerably less red shifted than six-coordinate Ni-porphyrin models. These results suggest that Ni in the second site possesses a single axial ligand. Raman spectra of 64Ni-reconstituted and natural abundance Ni-reconstituted hemoglobins, obtained simultaneously in a Raman difference spectrometer, have identified the Ni-ligand stretch at 236 cm-1. The line shifts to 229 cm-1 for the 64Ni-reconstituted Hb. For a pure Ni-ligand stretch a 10-cm-1 shift would be predicted.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
98.
A novel target-sensitive immunoliposome was prepared and characterized. In this design, target-specific binding of antibody-coated liposomes was sufficient to induce bilayer destabilization, resulting in a site-specific release of liposome contents. Unilamellar liposomes were prepared by using a small quantity of palmitoyl-immunoglobulin G (pIgG) to stabilize the bilayer phase of the unsaturated dioleoylphosphatidylethanolamine (PE) which by itself does not form stable liposomes. A mouse monoclonal IgG antibody to the glycoprotein D of Herpes simplex virus (HSV) and PE were used in this study. A minimal coupling stoichiometry of 2.2 palmitic acids per IgG was essential for the stabilization activity of pIgG. In addition, the minimal pIgG to PE molar ratio for stable liposomes was 2.5 X 10(-4). PE immunoliposomes bound with HSV-infected mouse L929 cells with an apparent Kd of 1.00 X 10(-8) M which was approximately the same as that of the native antibody. When 50 mM calcein was encapsulated in the PE immunoliposomes as an aqueous marker, binding of the liposomes to HSV-infected cells resulted in a cell concentration dependent lysis of the liposomes as detected by the release of the encapsulated calcein. Neither uninfected nor Sendai virus infected cells caused a significant amount of calcein release. Therefore, the release of calcein from PE immunoliposomes was target specific. Dioleoylphosphatidylcholine immunoliposomes were not lysed upon contact with infected cells under the same conditions, indicating that PE was essential for the target-specific liposome destabilization.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
99.
Identification of a protein encoded by the trans activator gene tatIII of human T-cell lymphotropic retrovirus type III. 总被引:9,自引:3,他引:6
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The human T-cell lymphotropic virus type III (HTLV-III/LAV) is a retrovirus associated with acquired immune deficiency syndrome. The region on the viral genome that is necessary for trans-activation of the HTLV-III/LAV long terminal repeat called tatIII has previously been determined to lie between nucleotides 5365 and 5607. Here we report that a bacterial fusion protein containing amino acid sequences specified by the first coding exon of the tatIII gene is recognized by some patient antisera. We also demonstrate that lymphoid and epithelial cells that express the trans activator function express a 14-kilodalton (kDa) protein recognized by a patient antiserum that reacts with the bacterial tatIII fusion protein. Cells transiently transfected with a deletion mutant of the trans activator protein produce a 12-kDa protein rather than the 14-kDa protein. These observations indicate that the tatIII region contains a functional gene and is capable of expressing a protein that migrates with an apparent molecular size of 14 kDa in some lymphoid and epithelial cells transfected with plasmids containing the tatIII region. We propose that the product of the trans activator gene be designated p14tat-III. 相似文献
100.
Hormonal regulation of the development of protease and carboxypeptidase activities in barley aleurone layers 总被引:13,自引:6,他引:7
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Carboxypeptidase and protease activities of hormone-treated barley (Hordeum vulgare cv Himalaya) aleurone layers were investigated using the substrates N-carbobenzoxy-Ala-Phe and hemoglobin. A differential effect of gibberellic acid (GA3) on these activities was observed. The carboxypeptidase activity develops in the aleurone layers during imbibition without the addition of hormone, while the release of this enzyme to the incubation medium is enhanced by GA3. In contrast, GA3 is required for both the production of protease activity in the aleurone layer and its secretion. The time course for development of protease activity in response to GA3 is similar to that observed for α-amylase. Treating aleurone layers with both GA3 and abscisic acid prevents all the GA3 effects described above. Carboxypeptidase activity is maximal between pH 5 and 6, and is inhibited by diisopropylfluorophosphate and p-hydroxymercuribenzoate. We have observed three protease activities against hemoglobin which differ in charge but are all 37 kilodaltons in size on sodium dodecyl sulfate polyacrylamide gels. The activity of the proteases can be inhibited by sulfhydryl protease inhibitors, such as bromate and leupeptin, yet is enhanced by 2-fold with 2-mercaptoethanol. In addition, these enzymes appear to be active against the wheat and barley storage proteins, gliadin and hordein, respectively. On the basis of these characteristics and the time course of GA3 response, it is concluded that the proteases represent the GA3-induced, de novo synthesized proteases that are mainly responsible for the degradation of endosperm storage proteins. 相似文献