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排序方式: 共有398条查询结果,搜索用时 15 毫秒
1.
J Rivera J M Mullins K Furuichi C Isersky 《Journal of immunology (Baltimore, Md. : 1950)》1986,136(2):623-627
Rat basophilic leukemia (RBL) cells have distinct receptors for IgE and IgG. We assessed the endocytosis of chemically and immunochemically cross-linked mouse-IgG and its influence on the simultaneous endocytosis of IgE. We found that at 37 degrees C, aggregates of IgG and IgE were endocytosed at about the same rate with one-half of the maximal endocytosis occurring in 5 to 13 min, and the efficiency of endocytosis for both ligands ranging from 40 to 70%. We also found that endocytosis of cross-linked IgE and IgG occurred simultaneously and neither ligand significantly affected the rate or extent of endocytosis of the other. The cells accumulated the cross-linked IgG, and then released it to the extracellular environment, at a rate (less than 3%/hr) slower than the released endocytosed IgE (greater than 10%/hr). Using an assay that discriminates between unbound and receptor-bound oligomeric IgG, we found that oligomeric IgG is endocytosed with its receptor, and that the bulk of the ligand remains bound to its receptor for greater than 120 min after endocytosis. The differences in the rate of release of endocytosed IgG vs IgE suggests that the intracellular fate or pathway of these two oligomeric ligands may differ. 相似文献
2.
Branched RNA covalently linked to the 5' end of a single-stranded DNA in Stigmatella aurantiaca: structure of msDNA 总被引:13,自引:0,他引:13
Stigmatella aurantiaca is a gliding, gram-negative bacterium that shows a spectacular fruiting body formation upon starvation of nutrient. This bacterium was found to contain approximately 500 copies per cell of a short single-stranded linear DNA (multicopy single-stranded DNA: msDNA). The primary structure of msDNA was determined and found to consist of 162 or 163 deoxyribonucleotides. Its unique chromosomal gene was cloned and sequenced. The msDNA was found to be attached to a branched RNA by its 5' end. Structural analysis of the branched RNA revealed that it consists of a triribonucleotide, 5'A-G-(C or U)3', and that msDNA is branched out from the 2' position of the rG residue forming a 2', 5' phosphodiester linkage with the dC residue at the 5' end of msDNA. 相似文献
3.
Augmentation of the generation of cytotoxic T lymphocytes against syngeneic tumor cells by recombinant human tumor necrosis factor 总被引:1,自引:0,他引:1
In order to clarify the effect of recombinant human tumor necrosis factor (rHu-TNF) on the antitumor T cell immune response, we examined the effect of rHu-TNF on the generation of cytotoxic T cells (CTL) against syngeneic tumor cells. Spleen cells from X5563 plasmacytoma-transplanted mice were stimulated in vitro with mitomycin C-treated X5563 cells in the presence or absence of rHu-TNF. The generation of CTL was augmented in a dose-dependent manner by the addition of rHu-TNF. The augmenting effect of rHu-TNF was more marked when indomethacin was added to the culture. The augmenting effect was observed only when rHu-TNF was added at the early stage of the generation of CTL. The cell surface phenotype of CTL generated was L3T4- and Lyt2+. The augmentation was shown not only by the chromium-51 release assay but also by the Winn assay. As to the specificity, the augmentation of CTL generation was observed by the addition of rHu-TNF when responder-primed spleen cells were stimulated with the tumor cells in vitro. On the other hand, augmentation was not observed when responder spleen cells were not stimulated with the tumor cells in vitro, or when responder spleen cells were obtained from normal mice. The CTL generated was not cytotoxic against other tumor cells of the same haplotype. Thus, rHu-TNF augmented the generation of CTL against syngeneic tumor cells in an antigen-specific manner. The in vivo effect of rHu-TNF was examined by administering rHu-TNF into X5563-bearing mice. The spleen cells of rHu-TNF-injected mice generated a much higher CTL activity against X5563 cells in vitro than did the spleen cells of uninjected mice. From these results, a possibility can be considered that in some cases, rHu-TNF may exert its antitumor activity by stimulating the immune system. 相似文献
4.
Furuichi Y Oogida T Mitsui C Matsuno M Takahashi T 《The Journal of nutritional biochemistry》1990,1(4):196-199
Glucose was combined covalently with the epsilon-amino groups of lysyl residues of bovine casein in the presence of sodium cyanoborohydride as a reducing reagent by reductive alkylation, forming stable secondary amine linkages. Solubility characteristics and nutritional values of the neoglycoprotein were examined. The degree of modification (%) of the glucosylated casein was 82.5. Solubility of the modified casein was increased by the attachment of glucose. The modification did not disturb the digestion of casein by pepsin or trypsin. Rat feeding experiments using 10% protein diets demonstrated that the protein efficiency ratio (PER) of the modified casein was 0.35 +/- 0.33 compared with 2.99 +/- 0.29 for the unmodified casein. When the modified casein was supplemented with L-lysine to equal the level of total lysine of unmodified casein, the PER value was increased to 2.21 +/- 0.29. Nitrogen balance experiments showed that the modified casein was digested completely. On the other hand, biological value and net protein utilization of the modified protein were shown to be considerably lower than those of the unmodified casein. 相似文献
5.
Highly mobile DNA segment of IncI alpha plasmid R64: a clustered inversion region. 总被引:10,自引:7,他引:3 下载免费PDF全文
When R64 DNA was digested with EcoRI, two DNA fragments not equimolar to the plasmid DNA were produced. A DNA region including these fragments was cloned (pKK009), and the pKK009 DNA sample was found to be a mixture of six or more DNA species with EcoRI, PstI, and AvaI cleavage sites at different positions, suggesting a complex rearrangement of DNA. When a part of the pKK009 DNA was removed by HindIII digestion, 33 different types of plasmids (pKK010-series plasmids) were obtained out of 58 clones tested, but no DNA rearrangement could be observed. On the basis of a comparison of the detailed restriction maps of these pKK010-series plasmids, we propose a model in which four DNA segments invert independently or in groups within the 1.95-kilobase region of R64, so that the arrangements of these four segments change randomly. The fixed pKK010-series plasmid DNA was again rearranged in the presence of R64, indicating that trans-acting gene function may be present to mediate the DNA rearrangement. The gene (tentatively designated as rci) was located on a 4.5-kilobase E9' fragment of R64. 相似文献
6.
Comparative sequence analysis of rotavirus genomic segment 6--the gene specifying viral subgroups 1 and 2 总被引:6,自引:3,他引:3 下载免费PDF全文
G W Both L J Siegman A R Bellamy N Ikegami A J Shatkin Y Furuichi 《Journal of virology》1984,51(1):97-101
Cloned DNA copies of rotavirus genomic segment 6 from simian 11 (subgroup 1) and human strain Wa (subgroup 2) rotaviruses have been used to determine the nucleotide sequences of the gene that determines viral subgroup specificity. Both genomic segments are 1,356 nucleotides in length and possess 5'- and 3'-terminal untranslated regions of 23 and 142 nucleotides, respectively. The inferred amino acid sequence reveals VP6 to be a polypeptide of 397 amino acids in which more than 90% of the amino acid sequence is conserved between the two viruses. There are 34 amino acid changes between the subgroup 1 and 2 polypeptides, most clustered in three regions of the molecule at residues 39 through 62, 80 through 122, and 281 through 315. 相似文献
7.
Interindividual distance and influence of dominance on feeding in a natural Japanese macaque troop 总被引:5,自引:0,他引:5
Takeshi Furuichi 《Primates; journal of primatology》1983,24(4):445-455
In a natural troop of Japanese macaques (Macaca fuscata yakui), the dominant-subordinate relationship restricted the feeding behavior of the subordinate in two ways: (1) the dominant
drives away the subordinate through agonistic interactions; and (2) the subordinate avoids approaching the dominant without
any agonistic interactions. These occurred only infrequently, and only when an interindividual distance was less than a certain
distance, which is called the “tolerance/intolerance” (T/I) distance. On the other hand, the usual interindividual distance
when feeding was much greater than the T/I distance. Therefore dominance has little influence on feeding in the study troop.
In the study troop, the T/I distance between kin-related females was shorter than that between unrelated individuals. Although
this difference may facilitate kin selection if the troop faces severe competition over concentrated food, the difference
does not seem to influence survival or reproductive rate in the study troop. 相似文献
8.
9.
Satou K.; Furuichi E.; Takiguchi K.; Takagi T.; Kuhara S. 《Bioinformatics (Oxford, England)》1993,9(3):259-265
We have developed a deductive database system PACADE for analyzing3-D and secondary structures of protein. The PA CADE systemconsists of a relational database created from Protein DataBank and a deductive engine DEE based on logic programming.It has the following features: (1) The system has an inferencemechanism. This means by which users can easily write and checkbiological hypotheses using logical and declarative rules insteadof procedural programs. (2) The relational database of the PACADE system stores data on bath 3-D and secondwy structuresof protein. The integration of this two level structure makesfeasible an abstract representation of the protein structure.We describe herein the design, functions, and implementationof this PACADE system. 相似文献
10.
The m7(G(5')pppN-pyrophosphatase activity previously detected in HeLa cells has been further characterized. Results from DEAE-cellulose column chromatography and polyacrylamide gel electrophoresis under nondenaturing conditions revealed only one enzyme activity in HeLa cell extracts which was capable of selectively hydrolyzing m7G(5')pppN to yield m7pG + ppN (where N = 2'-O-methylated or unmethylated ribonucleosides or oligonucleotides of up to 8 to 10 nucleosides in length). The majority (approximately 95%) of this activity was found in the cytoplasmic extract but appeared not to be associated with the lysosomal fraction. m7G(5')pppG was hydrolyzed by the partially purified enzyme in the absence of divalent cations at a pH optimum of 7.5 and a temperature optimum of 45 degrees, with a Michaelis constant (Km) of 1.7 micronM. Sedimentation analysis and gel filtration showed the molecular weight of the enzyme as approximately 81,000. Inhibition studies testing the effect of a number of prospective substrates on the rate of m7G(5')pppG hydrolysis have confirmed the importance of the methyl moiety at the N7 position of guanosine for enzyme-substrate interaction. Furthermore, the trimethylated guanosine-containing 5'-terminal structure derived from U-2 RNA was found not to serve as substrate, and 7-methylinosine, unlike 7-methylguanosine, was not an effective inhibitor of m7G(5')pppG hydrolysis. Thus, the 2-amino group of the 7-methylguanosine portion of m7G(5')pppN is also important for substrate interaction with this specific pyrophosphatase. 相似文献