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341.
F-spondin interaction with the apolipoprotein E receptor ApoEr2 affects processing of amyloid precursor protein 下载免费PDF全文
Hoe HS Wessner D Beffert U Becker AG Matsuoka Y Rebeck GW 《Molecular and cellular biology》2005,25(21):9259-9268
A recent study showed that F-spondin, a protein associated with the extracellular matrix, interacted with amyloid precursor protein (APP) and inhibited beta-secretase cleavage. F-spondin contains a thrombospondin domain that we hypothesized could interact with the family of receptors for apolipoprotein E (apoE). Through coimmunoprecipitation experiments, we demonstrated that F-spondin interacts with an apoE receptor (apoE receptor 2 [ApoEr2]) through the thrombospondin domain of F-spondin and the ligand binding domain of ApoEr2. Full-length F-spondin increased coimmunoprecipitation of ApoEr2 and APP in transfected cells and primary neurons and increased surface expression of APP and ApoEr2. Full-length F-spondin, but none of the individual F-spondin domains, increased cleavage of APP and ApoEr2, resulting in more secreted forms of APP and ApoEr2 and more C-terminal fragments (CTF) of these proteins. In addition, full-length F-spondin, but not the individual domains, decreased production of the beta-CTF of APP and Abeta in transfected cells and primary neurons. The reduction in APP beta-CTF was blocked by receptor-associated protein (RAP), an inhibitor of lipoprotein receptors, implicating ApoEr2 in the altered proteolysis of APP. ApoEr2 coprecipitated with APP alpha- and beta-CTF, and F-spondin reduced the levels of APP intracellular domain signaling, suggesting that there are also intracellular interactions between APP and ApoEr2, perhaps involving adaptor proteins. These studies suggest that the extracellular matrix molecule F-spondin can cluster APP and ApoEr2 together on the cell surface and affect the processing of each, resulting in decreased production of Abeta. 相似文献
342.
Hashizume T Horiuchi M Nonaka S Kasuya E Kojima M Hosoda H Kangawa K 《Regulatory peptides》2005,126(1-2):61-65
Ghrelin, a novel endogenous growth hormone (GH) secretagogue, has been shown to exert very potent and specific GH-releasing activity in rats and humans. However, little is known about its GH-releasing activity and endocrine effects in domestic animals. To clarify the effect of ghrelin on GH secretion in vivo in ruminants, plasma GH responses to intra-arterial and intra-hypothalamic injections of rat ghrelin (rGhrelin) were examined in goats and cattle. The intra-arterial injection of 1 microg/kg BW of rGhrelin in ovariectomized goats failed to stimulate GH release, however, a dosage of 3 microg/kg BW significantly increased plasma GH concentrations (P<0.05). GH levels peaked at 15 min after the injection, then decreased to basal concentrations within 1 h after the injection. However, the secretory response to 3 microg/kg BW of rGhrelin was weaker than that of growth hormone-releasing hormone (GHRH) (0.25 microg/kg BW) (P<0.05). An infusion of 10 nmol of ghrelin into the medial basal hypothalamus (arcuate nucleus) significantly stimulated the release of GH in male calves (P<0.05). GH levels began to rise just after the infusions and peaked at 10 min, then decreased to the basal concentrations within 1 h after the injection. The present results show that ghrelin stimulates GH release in ruminants. 相似文献
343.
Since McClintock [Nature 229:244-255, 1971] first reported menstrual synchrony in women, a number of studies have reported similar phenomena. Many researchers have suggested that one of the proximate factors leading to synchrony is spatial proximity among females (e.g., close friends or roommates). However, most studies on menstrual synchrony have been conducted in limited spaces, and it remains to be determined whether controlled environments, such as those used in experiments, actually exist in the wild. In this study, we analyzed the relationship between proximity and estrous synchrony using data from wild female chimpanzees at Mahale, Tanzania. In the cycling females, we observed two pairs that spent a large amount of time together. We compared the estrous synchrony indices (ESIs) between these two pairs and the other females. Our results showed that the ESIs of the high-proximity pairs did not differ from those of other pairs. . 相似文献
344.
Naohide Ageyama Yutaka Hanazono Hiroaki Shibata Fumiko Ono Hiromi Ogawa Takeyuki Nagashima Yasuji Ueda Yasuhiro Yoshikawa Mamoru Hasegawa Keiya Ozawa Keiji Terao 《Experimental Animals》2005,54(5):421-428
Hematopoietic stem cells in bone marrow can be mobilized into peripheral blood by cytokine administration. Cytokine-mobilized peripheral blood stem cells are of great use in clinical applications. We previously established a modified procedure for the collection of cytokine-mobilized peripheral blood cells from rhesus monkeys (Macaca mulata) using a commercially available apparatus originally developed for human subjects. In this study, we examined the efficacy and safety of this method with even smaller macaques, cynomolgus monkeys (Macaca fascicularis), which are equivalent to human newborns in body weight (mean = 3.3 kg). Using the manufacturer's unmodified protocol (n=6), one monkey died of cardiac failure and three developed severe anemia. In contrast, using our modified procedure (n=6), no such complication was observed in any animal. In addition, the harvested nuclear cell, mononuclear cell and CD34(+) cell counts were significantly higher with the modified method. The modified method should allow safe and efficient collection of cytokine-mobilized peripheral blood cells from non-human primates as small as human newborns in a non-invasive manner. 相似文献
345.
Phospholipase A2 (PLA2) from the venom of the snake Trimeresurus flavoviridis produced an increase in resting tension of isolated strips of rat stomach fundus. The contractions of the fundus strips induced by the PLA2 were significantly inhibited by treatment with 10(-6) M indomethacin and in Ca2+-free medium, while treatment of the fundus strips with nordihydroguaiaretic acid caused a marked potentiation of the PLA2-induced contraction. Atropine (10(-6) M), chlorpheniramine (10(-6) M) and methysergide (10(-6) M) had no effects on the contractions induced by PLA2, while tetrodotoxin (10(-6) M) significantly potentiated the contraction. From these results, it appears that exogenously applied PLA2 may cause contraction of the rat stomach fundus through the liberation of endogenous arachidonic acid which may then be transformed into prostaglandins. 相似文献
346.
Fujiko Ozawa Yoshitoshi Kasuya Hiroshi Hama Sachie Asada Tetsuo Inada Katsutoshi Goto 《Journal of neurochemistry》1997,69(2):562-569
Abstract: We investigated the effect of cytoskeleton modulators on endothelin-B (ETB ) receptor expression in rat primary cultured astrocytes. Northern blot analysis and a binding study revealed that colchicine and nocodazole, microtubule-disrupting agents, decreased the levels of both ETB receptor mRNA and the number of ET-1 binding sites in quiescent astrocytes. Down-regulation of both ETB receptor mRNA and the number of binding sites for ET-1 was also observed in quiescent astrocytes treated with taxol, a microtubule-stabilizing agent. In contrast, neither β-lumicolchicine, an inactive isomer of colchicine, nor cytochalasin D, a microfilament-disrupting agent, influenced ETB receptor expression. The level of ETB receptors in astrocytes was affected by the cell state, namely, proliferative, quiescent, or differentiated state. The order of ETB receptor expression according to the cell state was proliferative state < quiescent state ≪ differentiated state induced by dibutyryl cyclic AMP. Also, in proliferative astrocytes and differentiated astrocytes, colchicine significantly down-regulated both ETB receptor mRNA and the number of binding sites for ET-1. However, thymidine assay revealed that colchicine did not change quiescent astrocytes and differentiated astrocytes to a proliferative state. Furthermore, the increase in glutamine synthetase activity in differentiated astrocytes was not affected by colchicine. These results suggest that microtubule dynamics possibly regulates ETB receptor expression in astrocytes without affecting the cell state. 相似文献
347.
Yasuji Matsuoka Yoshihisa Kitamura Reiko Fukunaga Shun Shimohama Toshitaka Nabeshima Ikuo Tooyama Hiroshi Kimura Takashi Taniguchi 《Neurochemistry international》1997,30(6):533-542
Hypoxia is a major cause of ischaemia-induced neuronal damage. In the present study, we examined the effects of in vivo hypoxia on N-methyl-D-aspartate receptors (NMDAR) in the rat hippocampus. This model of in vivo hypoxia involved placing rats in a hypoxic chamber containing 5% O2 and 95% N2 for 30 min. In the hippocampus, neuronal cells in the CA3, the hilus of the dentate gyrus and the dentate gyrus (DG) were damaged. In the CA1, which is known to be vulnerable to ischaemic damage, neuronal cells did not show hypoxia-induced damage. In vivo hypoxia-induced damage caused morphological changes in neuronal cells, such as shrunken, spindle or triangular shapes accompanied by pyknotic nuclei, but did not induce the loss of neuronal cells. On the other hand, the number of binding sites for [3H]-1-[1-(2-thienyl)cyclohexyl]-3,4-piperidine hydrochloride (TCP) gradually decreased on and after 7 days, and then maximally decreased by 25% at 21 days after hypoxia. The number of NMDAR1-immunopositive cells was decreased by 22% in the DG, but was unchanged in the CA3. Furthermore, we examined the effect of a non-competitive NMDA antagonist, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,b]cyclohepten-5,10-imine hydrogen maleate (MK–801), on against in vivo hypoxia. The administration of MK–801 (3 mg/kg, i.p.), 30 min before hypoxia treatment, partly protected against neuronal damage in the DG, but not in the CA3. These results suggest that hypoxia-induced neuronal damage in the DG involves, in part, the activation of NMDAR. 相似文献
348.
Biochemical and molecular characterization of the polyhydroxybutyrate depolymerase of Comamonas acidovorans YM1609, isolated from freshwater. 下载免费PDF全文
K Kasuya Y Inoue T Tanaka T Akehata T Iwata T Fukui Y Doi 《Applied microbiology》1997,63(12):4844-4852
Comamonas acidovorans YM1609 secreted a polyhydroxybutyrate (PHB) depolymerase into the culture supernatant when it was cultivated on poly(3-hydroxybutyrate) [P(3HB)] or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] as the sole carbon source. The PHB depolymerase was purified from culture supernatant of C. acidovorans by two chromatographic methods, and its molecular mass was determined as 45,000 Da by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme was stable at temperatures below 37 degrees C and at pH values of 6 to 10, and its activity was inhibited by diisopropyl fluorophosphonate. The liquid chromatography analysis of water-soluble products revealed that the primary product of enzymatic hydrolysis of P(3HB) was a dimer of 3-hydroxybutyric acid. Kinetics of enzymatic hydrolysis of P(3HB) film were studied. In addition, a gene encoding the PHB depolymerase was cloned from the C. acidovorans genomic library. The nucleotide sequence of this gene was found to encode a protein of 494 amino acids (M(r), 51,018 Da). Furthermore, by analysis of the N-terminal amino acid sequence of the purified enzyme, the molecular mass of the mature enzyme was calculated to be 48,628 Da. Analysis of the deduced amino acid sequence suggested a domain structure of the protein containing a catalytic domain, fibronectin type III module as linker, and a putative substrate-binding domain. Electron microscopic visualization of the mixture of P(3HB) single crystals and a fusion protein of putative substrate-binding domain with glutathione S-transferase demonstrated that the fusion protein adsorbed strongly and homogeneously to the surfaces of P(3HB) single crystals. 相似文献
349.
Human placental ferritin receptor 总被引:3,自引:0,他引:3
M Takami K Mizumoto I Kasuya K Kino H H Sussman H Tsunoo 《Biochimica et biophysica acta》1986,884(1):31-38
Brush-border membranes from human placenta were prepared and their purity was clarified by biochemical and morphological methods. Ferritin binding to these prepared membranes was examined using horse spleen 125I-apoferritin, and was found to be completed within 10 min at 37 degrees C and pH 7.5. The amount of ferritin bound to the membranes was found to be proportional to the amount of membrane added and saturable for a given amount of the membrane in the presence of excess ligand. The membranes exhibited specific ferritin binding with a Ka of 2.3 X 10(7) M-1 at pH 7.5. A competitive binding assay indicated that horse spleen 125I-apoferritin binding was inhibited by a 10-fold molar excess of horse spleen ferric ferritin and a 500-fold molar excess of human transferrin. These results suggest that human placental brush-border membranes have specific receptors for horse spleen apoferritin molecules. 相似文献
350.
The reproductive behavior of the dragonfly,Orthetrum japonicum, is described. Behavioral processes of turnover of territorial males, simultaneous guarding of 2 females by a male, and copulation
by non-territorial males are described. The males with longer hind wings won the territorial conflicts more frequently. The
total duration of territorial residence of a given male was correlated with the number of his matings, but not correlated
with the length of his abdomen or hind wings. The territorial site with the lower degree of vegetation cover was occupied
by males more consistently. Males in more consistently occupied territorial sites did not have longer abdomen and hind wings
than males in less consistently occupied sites. The territorial site where the larger number of copulations was observed was
not occupied more consistently. Selection episode analysis using the method of Arnold & Wade (1984a, b) showed that direct
selection on the hind wing length favored the short wing and that direct selection on the abdomen length favored the long
abdomen during mating. 相似文献