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991.
Yamada S Shinya K Takada A Ito T Suzuki T Suzuki Y Le QM Ebina M Kasai N Kida H Horimoto T Rivailler P Chen LM Donis RO Kawaoka Y 《Journal of virology》2012,86(3):1411-1420
Quail are thought to serve as intermediate hosts of influenza A viruses between aquatic birds and terrestrial birds, such as chickens, due to their high susceptibility to aquatic-bird viruses, which then adapt to replicate efficiently in their new hosts. However, does replication of aquatic-bird influenza viruses in quail similarly result in their efficient replication in humans? Using sialic acid-galactose linkage-specific lectins, we found both avian (sialic acid-α2-3-galactose [Siaα2-3Gal] linkages on sialyloligosaccharides)- and human (Siaα2-6Gal)-type receptors on the tracheal cells of quail, consistent with previous reports. We also passaged a duck H3N2 virus in quail 19 times. Sequence analysis revealed that eight mutations accumulated in hemagglutinin (HA) during these passages. Interestingly, many of the altered HA amino acids found in the adapted virus are present in human seasonal viruses, but not in duck viruses. We also found that stepwise stalk deletion of neuraminidase occurred during passages, resulting in reduced neuraminidase function. Despite some hemagglutinin mutations near the receptor binding pocket, appreciable changes in receptor specificity were not detected. However, reverse-genetics-generated viruses that possessed the hemagglutinin and neuraminidase of the quail-passaged virus replicated significantly better than the virus possessing the parent HA and neuraminidase in normal human bronchial epithelial cells, whereas no significant difference in replication between the two viruses was observed in duck cells. Further, the quail-passaged but not the original duck virus replicated in human bronchial epithelial cells. These data indicate that quail can serve as intermediate hosts for aquatic-bird influenza viruses to be transmitted to humans. 相似文献
992.
Arisue N Hashimoto T Mitsui H Palacpac NM Kaneko A Kawai S Hasegawa M Tanabe K Horii T 《Molecular biology and evolution》2012,29(9):2095-2099
Apicoplast, a nonphotosynthetic plastid derived from secondary symbiotic origin, is essential for the survival of malaria parasites of the genus Plasmodium. Elucidation of the evolution of the apicoplast genome in Plasmodium species is important to better understand the functions of the organelle. However, the complete apicoplast genome is available for only the most virulent human malaria parasite, Plasmodium falciparum. Here, we obtained the near-complete apicoplast genome sequences from eight Plasmodium species that infect a wide variety of vertebrate hosts and performed structural and phylogenetic analyses. We found that gene repertoire, gene arrangement, and other structural attributes were highly conserved. Phylogenetic reconstruction using 30 protein-coding genes of the apicoplast genome inferred, for the first time, a close relationship between P. ovale and rodent parasites. This close relatedness was robustly supported using multiple evolutionary assumptions and models. The finding suggests that an ancestral host switch occurred between rodent and human Plasmodium parasites. 相似文献
993.
Slr0967 and Sll0939 induced by the SphR response regulator in Synechocystis sp. PCC 6803 are essential for growth under acid stress conditions 总被引:1,自引:0,他引:1
Uchiyama J Asakura R Kimura M Moriyama A Tahara H Kobayashi Y Kubo Y Yoshihara T Ohta H 《Biochimica et biophysica acta》2012,1817(8):1270-1276
994.
Tahara H Uchiyama J Yoshihara T Matsumoto K Ohta H 《Biochimica et biophysica acta》2012,1817(8):1360-1366
ATP-binding cassette (ABC) transporter proteins mediate energy-dependent transport of substrates across cell membranes. Numerous ABC transporter-related genes have been found in the Synechocystis sp. PCC6803 genome by genome sequence analysis including H(+), iron, phosphate, polysaccharide, and CO(2) transport-related genes. The substrates of many other ABC transporters are still unknown. To identify ABC transporters involved in acid tolerance, deletion mutants of ABC transporter genes with unknown substrates were screened for acid stress sensitivities in low pH medium. It was found that cells expressing the deletion mutant of slr1045 were more sensitive to acid stress than the wild-type cells. Moreover, slr1045 expression in the wild-type cells was increased under acid stress. These results indicate that slr1045 is an essential gene for survival under acid stress. The mutant displayed high osmotic stress resistance and high/low temperature stress sensitivity. Considering the temperature-sensitive phenotype and homology to the organic solvent-resistant ABC system, we subsequently compared the lipid profiles of slr1045 mutant and wild-type cells by thin-layer chromatography. In acid stress conditions, the phosphatidylglycerol (PG) content in the slr1045 mutant cells was approximately 40% of that in the wild-type cells. Moreover, the addition of PG to the medium compensated for the growth deficiency of the slr1045 mutant cells under acid stress conditions. These data suggest that slr1045 plays a role in the stabilization of cell membranes in challenging environmental conditions. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. 相似文献
995.
A family of tetrabiphenylporphyrin-based receptors has been synthesized. Receptor 7 showed sub-nanomolar affinity (K(d)=0.67 nM) in binding to the surface of cytochrome c. In addition, a stoichiometric amount of the receptor 7 caused a lowering in the T(m) of cytochrome c from 85 to 35 degrees C. 相似文献
996.
Sasaki S Imaeda T Hayase Y Shimizu Y Kasai S Cho N Harada M Suzuki N Furuya S Fujino M 《Bioorganic & medicinal chemistry letters》2002,12(16):2073-2077
The design and synthesis of a new class of nonpeptide luteinizing hormone-releasing hormone (LHRH) receptor antagonists, the 2-phenylimidazo[1,2-a]pyrimidin-5-ones, is reported. Among compounds described in this study, we identified the potent antagonist 15b with nanomolar in vitro functional antagonism. The result might suggest that the heterocyclic 5-6-ring system possessing a pendant phenyl group attached to the five-membered ring is the important structural feature for a scaffold of small molecule LHRH antagonists. 相似文献
997.
Bud-site selection in yeast offers an attractive system for studying cell polarity and asymmetric division. Haploids divide in an axial pattern, whereas diploids divide in a bipolar pattern. AXL1 is expressed in haploids but not diploids, and ectopic expression of AXL1 in diploids converts their bipolar budding pattern to an axial pattern. How Axl1 acts as a switch between the bipolar and axial patterns is not understood. Here we report that Axl1 localizes to the mother-bud neck and division site remnants of haploids. Axl1 is absent from diploids. Axl1 colocalizes with Bud3, Bud4, and Bud10, components of the axial landmark structure. This localization suggests that Axl1 couples the axial landmark with downstream polarity establishment factors. Consistent with such a role, Axl1 associated biochemically with Bud4 and Bud5. Genetic evidence suggests that Axl1 works with Bud3 and Bud4 to promote the activity of the Bud10 membrane protein. Given Axl1's suggested role in morphogenesis and cell fusion during mating, we also examined its localization during this process. Axl1 redistributes independently of the axial landmark to a tight cell surface dot at the tip of each mating projection. These dots are rapidly lost as prezygotes form. 相似文献
998.
M Kamoi Y Ogawa S Nakamura M Dogru T Nagai H Obata M Ito M Kaido T Kawakita Y Okada Y Kawakami S Shimmura K Tsubota 《PloS one》2012,7(9):e43688
Previous observations in a rat model of a non-Sjögren''s syndrome (non-SS) type of dry eye seen in users of visual display terminals (VDT) indicated that secretory vesicle (SV) accumulation in the lacrimal gland epithelia contributes to the condition. Here, to examine this possibility in humans, we compared the lacrimal gland histology and percent SV area in the cytoplasm of acinar epithelial cells using light microscopy and transmission electron microscopy, in patients with VDT work-related non-SS dry-eye (VDT group), SS-induced dry-eye, and autopsied normal controls. In addition, the VAMP8 (vesicle-associated membrane protein 8, an exocrine-pathway molecule) and Rab3D (mature vesicle marker) were histochemically examined in lacrimal gland tissue sections. The lacrimal gland acini were larger in the VDT group than in the SS group, and the percent SV area was significantly higher in the VDT group than in the normal controls (P = 0.021) or SS group (P = 0.004). Immunostaining revealed abnormal distributions of VAMP8 in the VDT and SS groups. Rab3D was more strongly expressed in the cytoplasm of acinar epithelial cells in the VDT group than in that of normal controls. The duration of VDT use was significantly longer in the VDT group than in the other groups. These findings suggest that excessive SV accumulation in the acinar epithelia may contribute to the reduced tear secretion in VDT users. 相似文献
999.
DA Geisler C Päpke T Obata A Nunes-Nesi A Matthes K Schneitz E Maximova WL Araújo AR Fernie S Persson 《The Plant cell》2012,24(7):2792-2811
1000.