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71.
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73.
Cultured cells ofThalictrum flavum take up berberine exogenously added to medium against the concentration gradient. This uptake was temperature-dependent and sensitive to plasma membrane-bound ATPase inhibitors such as sodium orthovanadate and diethylstilbestrol, indicating that the process is mediated by an energy-requiring system. The time-course of pH-shift during berberine uptake suggests the participation of a berberine-proton antiport system in the berberine uptake by the cultured cells. In addition, the existence of a specific transport system was suggested by the competitive inhibition of berberine uptake by berberine analogues, coptisine and jatrorrhizine. 相似文献
74.
Primary production of phytoplankton and secondary production of a daphnid and a chaoborid were studied in a small eutrophic
pond. The gross primary production of phytoplankton was 290 gC m−2 per 9 months during April–December. Regression analysis showed that the gross primary production was related to the incident
solar radiation and the chlorophylla concentration and not to either total phosphorus or total inorganic nitrogen concentration. The mean chlorophylla concentration (14.2 mg m−3), however, was about half the expected value upon phosphorus loading of this pond. The mean zooplankton biomass was 1.60
g dry weight m−2, of whichDaphnia rosea and cyclopoid copepods amounted to 0.69 g dry weight m−2 and 0.61 g dry weight m−2, respectively. The production ofD. rosea was high during May–July and October and the level for the whole 9 months was 22.6 g dry weight m−2.Chaoborus flavicans produced 10 complete and one incomplete cohorts per year. Two consecutive cohorts overlapped during the growing season. The
maximum density, the mean biomass, and the production were 19,100 m−2, 0.81 g dry weight m−2, and 11.7 g dry weight m−2yr−1, respectively. As no fish was present in this pond, the emerging biomass amounted to 69% of larval production. The production
ofC. flavicans larvae was high in comparison with zooplankton production during August–September, when the larvae possibly fed not only
on zooplankton but also algae. 相似文献
75.
Quantitative analysis of serum IL-6 and its correlation with increased levels of serum IL-2R in HIV-induced diseases 总被引:11,自引:0,他引:11
M Honda K Kitamura Y Mizutani M Oishi M Arai T Okura K Igarahi K Yasukawa T Hirano T Kishimoto 《Journal of immunology (Baltimore, Md. : 1950)》1990,145(12):4059-4064
We have devised a luminescence sandwich ELISA for the quantification of IL-6 in both sera and cell culture supernatants, which had a detection limit of 100 fg/ml of test sample. By using the luminescence sandwich-ELISA, low but measurable levels of IL-6 (9.5 pg/ml on average) were found in the sera from normal individuals. The serum levels of IL-6 were elevated in HIV-seropositive asymptomatic carriers (55.5 pg/ml on average), and the IL-6 levels were correlated with the degree of HIV-induced disease progression (AIDS-related complex 106.8 pg/ml on average and (AIDS 283 pg/ml). IL-6 immunoreactivity in the sera of AIDS patients eluted at a 25,000 m.w. major peak, which was biologically active and heat-stable, and a 500,000 m.w. minor peak in size-exclusion HPLC. Interestingly, a significant correlation was observed between the serum IL-6 levels and soluble IL-2R levels. In vitro, HIV infection of PHA-activated PBMC led to enhanced release of IL-6 into the culture supernatants. Moreover, soluble IL-2R release was markedly increased by adding exogenous IL-6, whereas it was decreased by adding the neutralizing anti-IL-6 mAb to the cultures. These results demonstrate that increased IL-6 levels are significantly associated with sIL-2R levels, and suggest a cause of the increased levels of this receptor in patients with HIV infection. Furthermore, both serum IL-6 and serum IL-2R levels in HIV infection reflect the stage of the HIV-induced disease. 相似文献
76.
Necessity of IgE antibodies and mast cells for manifestation of resistance against larval Haemaphysalis longicornis ticks in mice 总被引:5,自引:0,他引:5
H Matsuda N Watanabe Y Kiso S Hirota H Ushio Y Kannan M Azuma H Koyama Y Kitamura 《Journal of immunology (Baltimore, Md. : 1950)》1990,144(1):259-262
Genetically mast cell-deficient WBB6F1-W/Wv mice showed an apparent defect in manifestation of the resistance against larval Haemaphysalis longicornis ticks, but their serum IgE levels increased more than 100-fold after the second tick infestation. Immune sera obtained from the WBB6F1-W/Wv mice were adoptively transferred to the other WBB6F1-W/Wv mice which had received intracutaneous injections of WBB6F1-+/+ mouse-derived cultured mast cells. Because the resistance against ticks was detectable only when both mast cells and IgE antibodies were available, immediate hypersensitivity reaction appeared to have a physiologic role in the manifestation of the resistance against H. longicornis ticks. 相似文献
77.
Ontogenesis of α2 -Adrenoceptor Coupling with GTP-Binding Proteins in the Rat Telencephalon 总被引:2,自引:2,他引:0
Yoshihisa Kitamura Makoto Mochii Ryuji Kodama Kiyokazu Agata Kenji Watanabe Goro Eguchi Yasuyuki Nomura 《Journal of neurochemistry》1989,53(1):249-257
The ontogenesis of alpha 2-adrenoceptors and GTP-binding proteins and their coupling activity were investigated in telencephalon membranes of developing rats. The manganese-induced elevation of [3H]clonidine binding was increased in an age-dependent manner but the guanosine 5'-O-(3-thio)triphosphate-induced decrease in binding did not change. The extent of the binding of [3H]clonidine at 15 nM (saturable concentration) increased in an age-dependent manner and reached the adult level at 4 days after birth. Cholera toxin and pertussis toxin catalyzed ADP-ribosylation of proteins of 46 and 41/39 kilodaltons (kDa) in solubilized cholate extracts of the membranes. The 41/39-kDa proteins ADP-ribosylated by pertussis toxin (Gi alpha + Go alpha) were increased with age and reached the adult level at day 12, whereas the 46-kDa protein (Gs alpha) reached its peak on day 12 and then decreased to the fetal level at the adult stage. The immunoblot experiments of the homogenates with antiserum (specific antibody against alpha- and beta-subunit of GTP-binding proteins) demonstrated that the 39-kDa alpha-subunit of (Go alpha) and the 36-kDa beta-subunit of GTP-binding protein (beta 36) increased with postnatal age. In contrast, 35-kDa beta-subunit (beta 35) did not change. From these results, it is suggested that the coupling activity of alpha 2-adrenoceptor with GTP-binding protein gradually develops in a manner parallel with the increase of alpha 2-adrenoceptor and pertussis toxin sensitive GTP-binding proteins, Gi, and that alpha 39 beta 36 gamma may be related to the differentiation and/or growth of nerve cells in rat telencephalon. 相似文献
78.
A mutant hemolysin with lower biological activity produced by a mutant Vibrio parahaemolyticus 总被引:1,自引:0,他引:1
Takeshi Honda Yuxin Ni Schunkichi Hori Hikaru Takakura Susumu Tsunasawa Fumino Sakiyama Toshio Miwatani 《FEMS microbiology letters》1989,61(1-2):95-100
Abstract A mutant toxin (m-TDH) of thermostable direct hemolysin (Vp-TDH) of Vibrio parahaemolyticus w was isolated from the culture of a strain of this organism mutagenized with N -methyl- N '-nitro- N -nitrosoguanidine. Although the m-TDH had a molecular structure similar to the native Vp-TDH, the m-TDH retained only about 7% residual hemolytic activity of the native toxin. Furthermore, other biological activities of m-TDH, such as lethality in mice and enterotoxicity in rabbit ileal loops, were also weakened. The m-TDH was immunologically indistinguishable from the native Vp-TDH. These results suggest that the m-TDH is only slightly different in structure from the native Vp-TDH. Also, the mutagenized site in m-TDH, which is not immunogenic, seems to be involved in expressing not only hemolytic activity but also lethal and enterotoxic activity. 相似文献
79.
K Kitamura K Uyeda F C Hartman K Kangawa H Matsuo 《The Journal of biological chemistry》1989,264(11):6344-6348
Fructose-6-P binding sites of rat liver and bovine heart Fru-6-P,2-kinase:Fru-2,6-bisphosphatase were investigated with an affinity labeling reagent, N-bromoacetylethanolamine phosphate. The rat liver enzyme was inactivated 97% by the reagent in 60 min, and the rate of inactivation followed pseudo-first order kinetics. The bovine heart enzyme was inactivated 90% within 60 min, but the inactivation rate followed pseudo-first order up to 80% inactivation and then became nonlinear. The presence of fructose-6-P retarded the extent of the inactivation to approximately 40% in 60 min. In order to determine the amino acid sequence of the fructose-6-P binding site, both enzymes were reacted with N-bromo[14C]acetylethanolamine-P and digested with trypsin; radiolabeled tryptic peptides were isolated and sequenced. A single 14C-labeled peptide was isolated from the rat liver enzyme, and the amino acid sequence of the peptide was determined as Lys-Gln-Cys-Ala-Leu-Ala-Leu-Lys. A major and two minor peptides were isolated from bovine heart enzyme whose amino acid sequences were Lys-Gln-Cys-Ala-Leu-Val-Ala-Leu-Lys, Arg-Ile-Glu-Cys-Tyr-Lys, and Ile-Glu-Cys-Tyr-Lys, respectively. In all cases, N-bromoacetylethanolamine-P had alkylated the cysteine residues. The amount of bromo[14C]acetylethanolamine-P incorporated into rat liver and beef heart was 1.3 mol/mol of subunit and 2.1 mol/mol of subunit, respectively, and the incorporations in the presence of Fru-6-P were reduced to 0.34 mol/mol of subunit and 0.9 mol/mol of subunit, respectively. Thus, the main fructose-6-P binding site of rat liver and bovine heart enzymes was identical except for a single amino acid substitution of valine for alanine in the latter enzyme. This peptide corresponded to residues 105 to 113 from the N terminus of the known amino acid sequence of rat liver enzyme, but since the complete sequence of bovine heart enzyme is not known, the location of the same peptide in the heart enzyme cannot be assigned. 相似文献
80.
Protein kinase C phosphorylation of desmin at four serine residues within the non-alpha-helical head domain 总被引:12,自引:0,他引:12
S Kitamura S Ando M Shibata K Tanabe C Sato M Inagaki 《The Journal of biological chemistry》1989,264(10):5674-5678
We reported that phosphorylation by either cAMP-dependent protein kinase or protein kinase C (Ca2+/phospholipid-dependent enzyme) in vitro induces disassembly of the desmin filaments (Inagaki, M., Gonda, Y., Matsuyama, M., Nishizawa, K., Nishi, Y., and Sato, C. (1988) J. Biol. Chem. 263, 5970-5978). For this subunit protein, Ser-29, Ser-35, and Ser-50 within the non-alpha-helical head domain were shown to be the sites of phosphorylation for cAMP-dependent protein kinase (Geisler, N., and Weber, K. (1988) EMBO J. 7, 15-20). In the present work, we identified the sites of desmin phosphorylated in vitro by other protein kinase which affects the filament structure. The protein kinase C-phosphorylated desmin was hydrolyzed with trypsin, and the phosphorylated peptides were isolated by reverse-phase chromatography. Sequential analysis of the purified phosphopeptides, together with the known primary sequence, revealed that Ser-12, Ser-29, Ser-38, and Ser-56 were phosphorylated by protein kinase C. All four sites are located within the non-alpha-helical head domain of desmin. Ser-12, Ser-38, and Ser-56, specifically phosphorylated by protein kinase C, have arginine residues at the carboxyl-terminal side (Arg-14, Arg-42, and Arg-59, respectively). Ser-29 phosphorylated by both protein kinase C and cAMP-dependent protein kinase has arginine residues at the amino and carboxyl termini (Arg-27 and Arg-33). These findings support the view that the head domain-specific phosphorylation strongly influences desmin filament structure; however, each protein kinase differed with regard to site recognition on this domain. 相似文献