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31.
Hydrophobic protein (H protein) was isolated from membrane fractions of Bacillus subtilis and constituted into artificial membrane vesicles with lipid of B. substilis. Glutamate was accumulated into the vesicle when a Na+ gradient across the membrane was imposed. The maximum effect of Na+ on the transport was achieved at a concentration of about 40 mM, while the apparent Km for Na+ was approximately 8 mM. On the other hand, Km for glutamate in the presence of 50 mM Na+ was about 8 μM. Increasing the concentration of Na+ resulted in a decrease in Km for glutamate, maximum velocity was not affected. The transport was sensitive to monensin (Na+ ionophore).Glutamate was also accumulated when pH gradient (interior alkaline) across the membrane was imposed or a membrane potential was induced with K+-diffusion potential. The pH gradient-driven glutamate transport was sensitive to carbonylcyanide m-chlorophenylhydrazone and the apparent Km for glutamate was approximately 25 μM.These results indicate that two kinds of glutamate transport system were present in H protein: one is Na+ dependent and the other is H+ dependent. 相似文献
32.
The 14N nuclear relaxation times T1 and T2 in egg yolk phosphatidylcholine have been observed in single bilayer vesicles dispersed in the media of different viscosities, 1H2O and 2H2O. The lateral diffusion coefficient of lipid molecule D has been calculated according to the method reported earlier: D = 2.2 × 10?8cm2s?1 in 1H2O and 2.1 × 10?8cm2s?1 in 2H2O at 20°C. They are in excellent agreement. This result gives a strong basis of usefulness of 14N NMR method in the evaluation of D without introducing any system perturbation. 相似文献
33.
Tokuo Ogawa Junichi Sugenoya Norikazu Ohnishi Keiko Natsume Megumi Ochiai Motohiko Nishida Norihiko Shinoda Kenichi Katoh Ritsuko Imamura 《International journal of biometeorology》1991,35(1):18-23
In an attempt to detect differences in the thermal effect of infrared irradiation of different wavelengths, transient sweating response to infrared irradiation in various spectral regions was examined. In Series 1, the ventral or dorsal surface of the nude subject was irradiated repetitively for a period of 4 min (2 min on, 2 min off) by each of three kinds of infrared heaters with main emissivity in near-infrared (NIR; 0.7–2.8 m), intermediate-infrared (MIR; 1.5–5.8 m), and far-infrared (FIR; 2.8–25 m) regions. The sweating response on a non-irradiated area tended to be the greatest with MIR, while the magnitude of the sweating response on the irradiated area showed no consistent differences among various wavelengths. The results infer that MIR stimulated cutaneous thomoreceptors most effectively, while its direct effect on local sweat gland activity was minimal. In Series 2, the effects of 9–12 min irradiations in more restricted ranges of wavelength were compared by the combination of the three kinds of heaters with filters (translucent to wavelength ranges of 1.3–2.7, 2.7–3.5, 3.6–8.0 m, respectively). The sweating response on a remote area was predominantly greater with the range of 2.7–3.5 m than with the other wavelength ranges, while the local effect on sweating was minimal with this range. The results of Series 2 reinforce those of Series 1, indicating that the degree of stimulation of cutaneous thermoreceptors and of direct thermal effect on sweat gland activity differ with spectral regions incident on the skin, thus affecting local and remote effects on the sweating response. 相似文献
34.
Keiko Natsume Tokuo Ogawa Junichi Sugenoya Norikazu Ohnishi Kazuno Imai 《International journal of biometeorology》1992,36(1):1-4
To investigate the effects of age on thermal sensitivity, preferred ambient temperature (T
pref) was compared between old (71–76 years) and young (21–30 years) groups, each consisting of six male subjects in summer and winter. The air temperature (T
a) was set at either 20° C or 40° C at commencement. The subject was directed to adjust theT
a for 45 min by manipulating a remote control switch to the level at which he felt most comfortable. In the older group, theT
pref was significantly lower in trials starting at 20° C than that starting at 40° C in summer. The fluctuation ofT
pref (temperature difference between maximum and minimumT
a during the last 10 min) was significantly wider in the older group in both summer and winter. Repetition of the same experiment on each subject showed a poorer reproducibility ofT
pref in the older group than in the younger group in summer. Tympanic and esophageal temperatures of the older group kept falling throughout the trial starting at 20° C in summer. These results suggest that thermal sensitivity is decreased with advancing age and that thermal perception in the elderly, especially to cold, is less sensitive in summer. 相似文献
35.
Kiyofumi Asai Takayoshi Hirano Shuji Kaneko Akihiko Moriyama Keiko Nakanishi Ichiro Isobe Yaman Z. Eksioglu Taiji Kato 《Journal of neurochemistry》1992,59(1):307-317
Neurofibroma tissue was investigated for the presence of glial growth modulators that would suppress the proliferation of glial cells. A novel endogenous polypeptide inhibitor of proliferation and DNA synthesis in glial cells, gliostatin, was purified from the extracts of neurofibroma by a procedure comprising dye and anion-exchange column chromatography, and HPLC. A monoclonal antibody raised against partially purified gliostatin showed no cross-reactivity with known cytokines, but adsorbed the growth inhibitory activity of gliostatin and immunochemically visualized the putative gliostatin bands on western blot analyses. Although the product showed an apparent M(r) of 100,000 accompanied by an inhibitory activity on gel filtration column chromatography, it migrated at a lower apparent M(r) of 50,000 under the reducing conditions on western blotting, indicating that a homodimeric structure of native gliostatin consisted of 50-kDa subcomponents. Gliostatin was a potent growth inhibitor acting at nanomolar concentrations against all glial tumor cells and glia maturation factor-stimulated astroblasts, but not neuronal cells. 相似文献
36.
To assess the role interleukins and mitogens play in regulating immunoglobulin (Ig) gene expression via the Ig enhancer and promoter, transgenic mice carrying two different Ig gene regulatory regions were generated. One, EkCAT, contains the Ig heavy chain enhancer (E) and the light chain promoter driving the chloramphenicol acetyltransferase (CAT) gene. In the other, EkCAT, CAT is under the control of the promoter alone. E and relative activity were assessed by CAT assay. In EkCAT mice, low CAT expression was consistently found in spleen, bone marrow, mesenteric lymph node, and thymus but not in brain, lung, or kidney. In EkCAT mice, CAT expression was detectable just above background in lymphoid tissues, suggesting a basic level of tissue specificity in the absence of the enhancer. Whole spleen cell cultures prepared from the mice were treated with lymphokines and mitogens. Lipopolysaccharide (LPS), concanavilin A (Con A), interleukin 6 (IL-6), and interferon- (IFN-) increased CAT expression to varying extents in cells derived from EkCAT mice but not in spleen cells prepared from EkCAT mice. Thus, the presence of E, in addition to the promoter, is essential for the stimulation of CAT expression mediated by these factors. B cells from EkCAT mice were separated by density into populations of small and large cells. In untreated small B cells, no CAT expression was detected and only addition of LPS resulted in an increase in CAT expression. In large B cells, CAT was expressed at a low level without addition of exogenous factors. Incubation with LPS, IL-6, Con A and IFN- caused CAT expression to increase several-fold. This transgenic system provides a means to identify exogenous factors that activate Ig enhancers and promoters.This work has been submitted in partial fulfillment of the requirements for the doctoral degree from the George Washington University. 相似文献
37.
Masashi Fujiwara Keiko Fukushi Mitsuo Takai Jisuke Hayashi Masahiro Fukaya Hajime Okumura Yoshiya Kawamura 《Biotechnology letters》1992,14(7):539-542
Summary Shuttle vector pUF106 was constructed by ligation ofAcetobacter xylinum plasmid pFF6 toEscherichia coli plasmid pUC18. It had unique restriction sites suitable for insertion of a foreign DNA fragment and conferred ampicillin resistance to a host. pUF106 transformed cellulose-producingA. xylinum ATCC10245 as well asE. coli JM109. 相似文献
38.
The sesquiterpene lactone koningic acid (heptelidic acid) irreversibly inactivated glyceraldehyde-3-phosphate dehydrogenase [D-glyceraldehyde 3-phosphate: NAD+ oxidoreductase (phosphorylating)] (EC 1.2.1.12) (GAPDH) and thus inhibits glycolysis. The koningic-acid-producing strain of Trichoderma koningii M3947 was shown to contain the koningic-acid-resistant GAPDH isozyme (GAPDH I) under conditions of koningic acid production. In peptone-rich medium, however, no koningic acid production was observed, and the koningic-acid-sensitive GAPDH isozyme (GAPDH II), in addition to the resistant enzyme, was produced. Both enzymes were tetramer with a molecular mass of 152 kDa (4 x 38 kDa) and lost enzyme activity when two of the four cysteine residues reacted with koningic acid. The apparent Km values of GAPDH I and II for glyceraldehyde 3-phosphate were 0.54 mM and 0.33 mM, respectively. The former isozyme was inhibited 50% by 1 mM koningic acid but not affected at 0.1 mM, while the latter isozyme was inhibited 50% at 0.01 mM. The immunochemical properties and partial amino acid sequences suggested that the two isozymes have different molecular structures. These results suggest that GAPDH I is responsible for the glycolysis in T. koningii when koningic acid is produced. 相似文献
39.
Probable Contribution of Protein Phosphorylation by Protein Kinase C to Spicule Formation in Sea Urchin Embryos 总被引:3,自引:3,他引:0
Keiko Mitsunaga Shio Shinohara Ikuo Yasumasu 《Development, growth & differentiation》1990,32(3):335-342
The formation of spicules and development of pluteus arms in sea urchin embryos were strongly blocked by H-7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride) but were not affected by HA1004 ( N -(2-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride). Archenteron formation occurred normally in the presence of these compounds. Late gastrulae (28 hr after fertilization) were exposed to 32 Pi for 30 min at 20°C, and then dissociated and their primary mesenchyme cells with spicules, embryo-wall cells and archenteron cells were separated. Then, the radioactivities in the protein fractions of these separated cells were measured. Results showed that culture of embryos with H-7 strongly inhibited 32 p incorporation into proteins in primary mesenchyme cells but caused little inhibition of its incorporations in embryo-wall cells and archenteron cells. The effective concentrations of H-7 for inhibition of 32 p incorporation were within the range that blocked spicule formation and growth of pluteus arms in embryos. HA1004 only slightly inhibited 32 p incorporation into protein in mesenchyme cells, embryo-wall cells and archenteron cells of embryos exposed to 32 Pi. Protein kinase C activity was detectable only in isolated primary mesenchyme cells associated with spicule structures. These suggest that phosphorylation of proteins by protein kinase C contributes to the formation of spicule structures. 相似文献
40.
In brain tissue a spectrin-like calmodulin-binding protein calspectin, or fodrin, is concentrated in a synaptosome fraction, where most of the calspectin is associated with the synaptic membranes. This endogenous calspectin was phosphorylated by protein kinase system(s) associated with the membranes. Here, we report the solubilization and partial purification of the membrane-associated calspectin kinase activity. The activity was resolved on a gel filtration column into two fractions, peaks I and II having estimated Mr of 800 000 and 88 000. The activity of peak I was dependent on the presence of both Ca2+ and calmodulin. Peak II revealed a basal activity in the absence of Ca2+ and calmodulin, which was stimulated 2-fold by addition of Ca2+. Calmodulin had no effect on the peak II activity. 相似文献