排序方式: 共有46条查询结果,搜索用时 31 毫秒
31.
Bifidobacteria can protect from enteropathogenic infection through production of acetate 总被引:3,自引:0,他引:3
Fukuda S Toh H Hase K Oshima K Nakanishi Y Yoshimura K Tobe T Clarke JM Topping DL Suzuki T Taylor TD Itoh K Kikuchi J Morita H Hattori M Ohno H 《Nature》2011,469(7331):543-547
The human gut is colonized with a wide variety of microorganisms, including species, such as those belonging to the bacterial genus Bifidobacterium, that have beneficial effects on human physiology and pathology. Among the most distinctive benefits of bifidobacteria are modulation of host defence responses and protection against infectious diseases. Nevertheless, the molecular mechanisms underlying these effects have barely been elucidated. To investigate these mechanisms, we used mice associated with certain bifidobacterial strains and a simplified model of lethal infection with enterohaemorrhagic Escherichia coli O157:H7, together with an integrated 'omics' approach. Here we show that genes encoding an ATP-binding-cassette-type carbohydrate transporter present in certain bifidobacteria contribute to protecting mice against death induced by E. coli O157:H7. We found that this effect can be attributed, at least in part, to increased production of acetate and that translocation of the E. coli O157:H7 Shiga toxin from the gut lumen to the blood was inhibited. We propose that acetate produced by protective bifidobacteria improves intestinal defence mediated by epithelial cells and thereby protects the host against lethal infection. 相似文献
32.
基于3维环境的空间统计信道,提出MIMO天线阵列下的VMF分布模型.研究MIMO多天线ULA,UYA和UCA在移动台和基站的拓扑结构,得到VMF(Von Mises Fisher)分布模型下ULA,UYA和UCA的空间衰落相关性(SFC)函数的表达式,比较不同天线阵列对平均仰角(MEOA)的灵敏度.研究表明,MIMO天线阵列的SFC由集中参数、平均方位角(MAOA)及平均仰角(MEOA)决定,该模型的信道性能结果与理论一致. 相似文献
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Radixin deficiency causes conjugated hyperbilirubinemia with loss of Mrp2 from bile canalicular membranes 总被引:9,自引:0,他引:9
Kikuchi S Hata M Fukumoto K Yamane Y Matsui T Tamura A Yonemura S Yamagishi H Keppler D Tsukita S Tsukita S 《Nature genetics》2002,31(3):320-325
The ezrin-radixin-moesin (ERM) family of proteins crosslink actin filaments and integral membrane proteins. Radixin (encoded by Rdx) is the dominant ERM protein in the liver of wildtype mice and is concentrated at bile canalicular membranes (BCMs). Here we show that Rdx(-/-) mice are normal at birth, but their serum concentrations of conjugated bilirubin begin to increase gradually around 4 weeks, and they show mild liver injury after 8 weeks. This phenotype is similar to human conjugated hyperbilirubinemia in Dubin-Johnson syndrome, which is caused by mutations in the multidrug resistance protein 2 (MRP2, gene symbol ABCC2), although this syndrome is not associated with overt liver injury. In wildtype mice, Mrp2 concentrates at BCMs to secrete conjugated bilirubin into bile. In the BCMs of Rdx(-/-) mice, Mrp2 is decreased compared with other BCM proteins such as dipeptidyl peptidase IV (CD26) and P-glycoproteins. In vitro binding studies show that radixin associates directly with the carboxy-terminal cytoplasmic domain of human MRP2. These findings indicate that radixin is required for secretion of conjugated bilirubin through its support of Mrp2 localization at BCMs. 相似文献
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Zhu W Shiojima I Ito Y Li Z Ikeda H Yoshida M Naito AT Nishi J Ueno H Umezawa A Minamino T Nagai T Kikuchi A Asashima M Komuro I 《Nature》2008,454(7202):345-349
Insulin-like growth-factor-binding proteins (IGFBPs) bind to and modulate the actions of insulin-like growth factors (IGFs). Although some of the actions of IGFBPs have been reported to be independent of IGFs, the precise mechanisms of IGF-independent actions of IGFBPs are largely unknown. Here we report a previously unknown function for IGFBP-4 as a cardiogenic growth factor. IGFBP-4 enhanced cardiomyocyte differentiation in vitro, and knockdown of Igfbp4 attenuated cardiomyogenesis both in vitro and in vivo. The cardiogenic effect of IGFBP-4 was independent of its IGF-binding activity but was mediated by the inhibitory effect on canonical Wnt signalling. IGFBP-4 physically interacted with a Wnt receptor, Frizzled 8 (Frz8), and a Wnt co-receptor, low-density lipoprotein receptor-related protein 6 (LRP6), and inhibited the binding of Wnt3A to Frz8 and LRP6. Although IGF-independent, the cardiogenic effect of IGFBP-4 was attenuated by IGFs through IGFBP-4 sequestration. IGFBP-4 is therefore an inhibitor of the canonical Wnt signalling required for cardiogenesis and provides a molecular link between IGF signalling and Wnt signalling. 相似文献
37.
Yoshiura K Kinoshita A Ishida T Ninokata A Ishikawa T Kaname T Bannai M Tokunaga K Sonoda S Komaki R Ihara M Saenko VA Alipov GK Sekine I Komatsu K Takahashi H Nakashima M Sosonkina N Mapendano CK Ghadami M Nomura M Liang DS Miwa N Kim DK Garidkhuu A Natsume N Ohta T Tomita H Kaneko A Kikuchi M Russomando G Hirayama K Ishibashi M Takahashi A Saitou N Murray JC Saito S Nakamura Y Niikawa N 《Nature genetics》2006,38(3):324-330
Human earwax consists of wet and dry types. Dry earwax is frequent in East Asians, whereas wet earwax is common in other populations. Here we show that a SNP, 538G --> A (rs17822931), in the ABCC11 gene is responsible for determination of earwax type. The AA genotype corresponds to dry earwax, and GA and GG to wet type. A 27-bp deletion in ABCC11 exon 29 was also found in a few individuals of Asian ancestry. A functional assay demonstrated that cells with allele A show a lower excretory activity for cGMP than those with allele G. The allele A frequency shows a north-south and east-west downward geographical gradient; worldwide, it is highest in Chinese and Koreans, and a common dry-type haplotype is retained among various ethnic populations. These suggest that the allele A arose in northeast Asia and thereafter spread through the world. The 538G --> A SNP is the first example of DNA polymorphism determining a visible genetic trait. 相似文献
38.
Molecular identification of a renal urate anion exchanger that regulates blood urate levels 总被引:74,自引:0,他引:74
Enomoto A Kimura H Chairoungdua A Shigeta Y Jutabha P Cha SH Hosoyamada M Takeda M Sekine T Igarashi T Matsuo H Kikuchi Y Oda T Ichida K Hosoya T Shimokata K Niwa T Kanai Y Endou H 《Nature》2002,417(6887):447-452
Urate, a naturally occurring product of purine metabolism, is a scavenger of biological oxidants implicated in numerous disease processes, as demonstrated by its capacity of neuroprotection. It is present at higher levels in human blood (200 500 microM) than in other mammals, because humans have an effective renal urate reabsorption system, despite their evolutionary loss of hepatic uricase by mutational silencing. The molecular basis for urate handling in the human kidney remains unclear because of difficulties in understanding diverse urate transport systems and species differences. Here we identify the long-hypothesized urate transporter in the human kidney (URAT1, encoded by SLC22A12), a urate anion exchanger regulating blood urate levels and targeted by uricosuric and antiuricosuric agents (which affect excretion of uric acid). Moreover, we provide evidence that patients with idiopathic renal hypouricaemia (lack of blood uric acid) have defects in SLC22A12. Identification of URAT1 should provide insights into the nature of urate homeostasis, as well as lead to the development of better agents against hyperuricaemia, a disadvantage concomitant with human evolution. 相似文献
39.
The plant MITE mPing is mobilized in anther culture 总被引:13,自引:0,他引:13
Transposable elements constitute a large portion of eukaryotic genomes and contribute to their evolution and diversification. Miniature inverted-repeat transposable elements (MITEs) constitute one of the main groups of transposable elements and are distributed ubiquitously in the genomes of plants and animals such as maize, rice, Arabidopsis, human, insect and nematode. Because active MITEs have not been identified, the transposition mechanism of MITEs and their accumulation in eukaryotic genomes remain poorly understood. Here we describe a new class of MITE, called miniature Ping (mPing), in the genome of Oryza sativa (rice). mPing elements are activated in cells derived from anther culture, where they are excised efficiently from original sites and reinserted into new loci. An mPing-associated Ping element, which has a putative PIF family transposase, is implicated in the recent proliferation of this MITE family in a subspecies of rice. 相似文献
40.
Summary There is a 24 h periodicity of the rat liver tissue respiration (Qo2) with maximal values at about 07.30 h and minimal values at about 17.00 h.
Auslandsstipendiat der Schweizerischen Regierung (1963/64).
Die Arbeit wurde unterstützt von der Max-Planck-Gesellschaft zur Förderung der Wissenschaften, Deutschland. 相似文献
Auslandsstipendiat der Schweizerischen Regierung (1963/64).
Die Arbeit wurde unterstützt von der Max-Planck-Gesellschaft zur Förderung der Wissenschaften, Deutschland. 相似文献