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排序方式: 共有571条查询结果,搜索用时 187 毫秒
71.
Nakamura M Asaka T Kirita A Miyazaki H Senda Y Fujita S Fukushima R Watanabe K Karasawa T Kawahara E Shimura S Yamagishi T 《Microbiology and immunology》2006,50(4):327-329
The adherence of Haemophilus influenzae to epithelial cells plays a crucial role in infections. However, little is known about the occurrence of fimbriae. In this study, we examined the distribution of the fimbria gene (hifA) by PCR among 167 H. influenzae strains isolated from patients with respiratory infections. Almost all (163; 98%) of the isolates were nonencapsulated strains. The carriage rate of hifA by the nonencapsulated strains was 18.4%. Electron microscopy showed that fimbriae were abundantly present on the cell surface of hifA-positive strains tested. Only four (2.4%) isolates were encapsulated, all of which were type b and did not possess hifA. The present work suggests that fimbriae may play a considerable role as adhesins in nonencapsulated H. influenzae strains. 相似文献
72.
73.
In Synechococcus elongatus, the PII protein inhibits both transport and reduction of nitrate when ammonium is present in the medium. Using a transporter mutant having ammonium-resistant nitrate transport activity as the genetic background, we analyzed specific effects of PII on in vivo nitrate reductase activity by measuring uptake of nitrate from the medium. The results showed that the regulation of nitrate reductase does not require changes in the electric charge or size of the side chain at the phosphorylation site of PII. Phosphorylation of PII is thus unlikely to play a role in the regulation of nitrate reductase. 相似文献
74.
Sawai S Akashi T Sakurai N Suzuki H Shibata D Ayabe S Aoki T 《Plant & cell physiology》2006,47(5):673-677
Sterols, essential eukaryotic constituents, are biosynthesized through either cyclic triterpenes, lanosterol (fungi and animals) or cycloartenol (plants). The cDNA for OSC7 of Lotus japonicus was shown to encode lanosterol synthase (LAS) by the complementation of a LAS-deficient mutant yeast and structural identification of the accumulated lanosterol. A double site-directed mutant of OSC7, in which amino acid residues crucial for the reaction specificity were changed to the cycloartenol synthase (CAS) type, produced parkeol and cycloartenol. The multiple amino acid sequence alignment of a conserved region suggests that the LAS of different eukaryotic lineages emerged from the ancestral CAS by convergent evolution. 相似文献
75.
The vascular system of the mouse retina provides a useful model for analyzing the molecular and cellular mechanisms regulating angiogenesis because (1) hierarchical vascular networks are newly formed only after birth, (2) the cellular components involved in angiogenesis are well characterized, and (3) all the processes are accessible for monitoring and manipulation. In this article, we present an overview of our current understanding of the process of retinal angiogenesis and describe a number of methodologies applicable to experimental manipulation of the retinal vascular system. 相似文献
76.
77.
Senoh M Ghosh-Banerjee J Ramamurthy T Colwell RR Miyoshi S Nair GB Takeda Y 《Microbiology and immunology》2012,56(5):342-345
Viable but nonculturable (VBNC) Vibrio cholerae non-O1/non-O139, V. parahaemolyticus, enterohemorrhagic Escherichia coli, enterotoxigenic E. coli, enteropathogenic E. coli, Shigella flexneri, and Salmonella enterica were converted to the culturable state by co-culture with selected eukaryotic cells, e.g., HT-29, Caco-2, T84, HeLa, Intestine 407, and CHO cells. 相似文献
78.
Sekizawa S Horowitz JM Horwitz BA Chen CY 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2012,198(4):267-282
Crucial for survival, the central nervous system must reliably process sensory information over all stages of a hibernation
bout to ensure homeostatic regulation is maintained and well-matched to dramatically altered behavioral states. Comparing
neural responses in the nucleus tractus solitarius of rats and euthermic Syrian hamsters, we tested the hypothesis that hamster
neurons have adaptations sustaining signal processing while conserving energy. Using patch-clamp techniques, we classified
second-order neurons in the nucleus as rapid-onset or delayed-onset spiking phenotypes based on their spiking onset to a depolarizing
pulse (following a −80 mV prepulse). As temperature decreased from 33 to 15°C, the excitability of all neurons decreased.
However, hamster rapid-onset spiking neurons had the highest spiking response and shortest action potential width at every
temperature, while hamster delayed-onset spiking neurons had the most negative resting membrane potential. The frequency of
spontaneous excitatory postsynaptic currents in both phenotypes decreased as temperature decreased, yet the amplitudes of
tractus solitarius stimulation-evoked currents were greater in hamsters than in rats regardless of phenotype and temperature.
Changes were significant (P < 0.05), supporting our hypothesis by showing that, as temperature falls, rapid-onset neurons contribute more to signal processing
but less to energy conservation than do delayed-onset neurons. 相似文献
79.
A Bilitou N De Marco AM Bello L Garzia P Carotenuto M Kim C Campanella S Ohnuma M Zollo 《Gene》2012,509(1):93-103
The development of stratified retinal cell architecture is highly conserved in all vertebrates, implying that a common fundamental molecular mechanism is involved in the generation of the organized retina. However, the detailed molecular mechanisms of retinal development are not fully understood. Here we have identified the Xenopus ortholog of prune and show that it is expressed in both differentiating and differentiated retinal domains during development. Interestingly, these spatial and temporal expression patterns coincide with the expression of prune binding partners, the NM23 family members. Overexpression of prune in retinal precursor cells significantly increases the ratio of Müller glial cells as observed by modulation of NM23 activity (Mochizuki et al., 2009). However, a mutated form of prune that has replacement of four aspartate (D) residues (D'Angelo et al., 2004), essential for phosphodiesterase activity, does not exhibit gliogenic activity. Our observations suggest that Xenopus prune may regulate Müller gliogenesis through phosphodiesterase-mediated regulation of NM23 family members. 相似文献
80.
Y Kan T Okabayashi S Yokota S Yamamoto N Fujii T Yamashita 《Journal of virology》2012,86(19):10338-10346
Imiquimod is recognized as an agonist for Toll-like receptor 7 (TLR7) in immunocompetent cells. TLR7, as well as TLR3 and TLR8, triggers the immune responses, such as the production of type I interferons (IFNs) and proinflammatory cytokines via recognition of viral nucleic acids in the infected cells. In this study, we proposed that imiquimod has an IFN-independent antiviral effect in nonimmune cells. Imiquimod, but not resiquimod, suppressed replication of human herpes simplex virus 1 (HSV-1) in FL cells. We analyzed alternation of gene expression by treatment with imiquimod using microarray analysis. Neither type I IFNs, nor TLRs, nor IFN-inducible antiviral genes were induced in imiquimod-treated FL cells. Cystatin A, a host cysteine protease inhibitor, was strongly upregulated by imiquimod and took a major part in the anti-HSV-1 activity deduced by the suppression experiment using its small interfering RNA. Upregulation of cystatin A was suggested to be mediated by antagonizing adenosine receptor A(1) and activating the protein kinase A pathway. Imiquimod, but not resiquimod, was shown to interact with adenosine receptor A(1). Imiquimod-induced anti-HSV-1 activity was observed in other cells, such as HeLa, SiHa, and CaSki cells, in a manner consistent with the cystatin A induction by imiquimod. These results indicated that imiquimod acted as an antagonist for adenosine receptor A(1) and induced a host antiviral protein, cystatin A. The process occurred independently of TLR7 and type I IFNs. 相似文献