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81.
Kanatsu-Shinohara M Takehashi M Takashima S Lee J Morimoto H Chuma S Raducanu A Nakatsuji N Fässler R Shinohara T 《Cell Stem Cell》2008,3(5):533-542
Spermatogonial stem cells (SSCs) provide the foundation for spermatogenesis. In a manner comparable to hematopoietic stem cell transplantation, SSCs colonize the niche of recipient testes and reinitiate spermatogenesis following microinjection into the seminiferous tubules. However, little is known about the homing mechanism of SSCs. Here we examined the role of adhesion molecules in SSC homing. SSCs isolated from mice carrying loxP-tagged beta1-integrin alleles were ablated for beta1-integrin expression by in vitro adenoviral cre transduction. The beta1-integrin mutant SSCs showed significantly reduced ability to recolonize recipient testes in vivo and to attach to laminin molecules in vitro. In contrast, genetic ablation of E-cadherin did not impair homing, and E-cadherin mutant SSCs completed normal spermatogenesis. In addition, the deletion of beta1-integrin on Sertoli cells reduced SSC homing. These results identify beta1-integrin as an essential adhesion receptor for SSC homing and its association with laminin is critical in multiple steps of SSC homing. 相似文献
82.
83.
Detection of Noroviruses in Tap Water in Japan by Means of a New Method for Concentrating Enteric Viruses in Large Volumes of Freshwater 总被引:2,自引:1,他引:1 下载免费PDF全文
A virus concentration method using a cation-coated filter was developed for large-volume freshwater applications. Poliovirus type 1 (LSc 2ab Sabin strain) inoculated into 40 ml of MilliQ (ultrapure) water was adsorbed effectively to a negatively charged filter (Millipore HA, 0.45-μm pore size) coated with aluminum ions, 99% (range, 81 to 114%) of which were recovered by elution with 1.0 mM NaOH (pH 10.8) following an acid rinse with 0.5 mM H2SO4 (pH 3.0). More than 80% poliovirus recovery yields were obtained from 500-ml, 1,000-ml, and 10-liter MilliQ water samples and from tap water samples. This method, followed by TaqMan PCR detection, was applied to determine the presence of noroviruses in tap water in Tokyo, Japan. In a 14-month survey, 4 (4.1%) and 7 (7.1%) of 98 tap water samples (100 to 532 liters) contained a detectable amount of noroviruses of genotype 1 and genotype 2, respectively. This method was proved to be useful for surveying the occurrence of enteric viruses, including noroviruses, in large volumes of freshwater. 相似文献
84.
Kumemura H Harada M Yanagimoto C Koga H Kawaguchi T Hanada S Taniguchi E Ueno T Sata M 《Biochemical and biophysical research communications》2008,367(1):33-40
Microtubules (MTs) and microfilaments (MFs) are known to modulate mitochondrial morphology, distribution and function. However, little is known evidence about the role of intermediate filaments (IFs) in modulating mitochondria except desmin. To investigate whether or not the IFs regulate mitochondrial morphology, distribution, and function, we manipulated the IFs of cultured epithelial cells to express a mutant keratin 18 (K18). In contrast to the filamentous expression of wild K18, mutant K18 induced aggregation of K8/18, showing no fine IF network in the cells. In mutant K18-transfected cells, the mitochondria were fragmented into small spheroids, although they were observed as mitochondrial fibers in un-transfected or wild K18-transfected cells. Fluorescence recovery after photobleaching of fluorescence-labeled mitochondria was markedly less in the mutant K18-transfected cells, although a significant recovery was confirmed in wild K18-transfected cells. These findings suggest that the IFs are important for the maintenance of normal mitochondrial structures. 相似文献
85.
A ten-year summary of reproductive parameters for ring-tailed lemurs at berenty, madagascar 总被引:2,自引:2,他引:0
Naoki Koyama Masayuki Nakamichi Ryo Oda Naomi Miyamoto Shinichiro Ichino Yukio Takahata 《Primates; journal of primatology》2001,42(1):1-14
From 1989 to 1998, 204 live births were recorded for ring-tailed lemurs (Lemur catta) at Berenty, Madagascar. Excluding unknown birth dates, the peak month of birth was September, with 82.0% (146/178) occurring
during this period. The offspring sex ratio (1∶1.19) was not significantly different from 1∶1, and there was no association
with the mother's age. The first births occurred at the ages of 2 to 4 yr. The annual birth rate was very low at the age of
2 yr (11.1%), but increased thereafter: to 50.0% at the age of 3 yr, and to 75–85% at the age of 4 or more years. Multiple
births were very rare, since only three sets of twins and one set of triplets were recorded. As for the interbirth interval,
a one-year interval was the most common (92.2%). Infant mortality within the first year was 37.7% (77/204). Neonatal mortality
within the first month accounted for 31.2% of all infant dealths. 相似文献
86.
87.
Yukiko Hiraiwa Akihiro Morinaka Takayoshi Fukushima Toshiaki Kudo 《Bioorganic & medicinal chemistry letters》2009,19(17):5162-5165
4-Butyl-3-methylphthalic acid was recognized as a metallo-β-lactamase inhibitor. The structure–activity relationship study of substituted phthalic acids afforded 3-phenylphthalic acid derivatives as potent IMP-1 inhibitors. On the other hand, 3-substituted with 4-hydroxyphenyl phthalic acid derivative displayed a potent combination effect with biapenem (BIPM) against Pseudomonas aeruginosa that produce IMP-1. 相似文献
88.
89.
Shinichiro Gondo Shogo Isayama Koichiro Kusunoki 《Biotechnology and bioengineering》1975,17(3):423-431
The effect of internal diffusion on the slope and the intercept of the LineweaverBurk plots for the immobilized enzyme was considered theoretically and it was found that the slope and the intercept are influenced not only by the dimensionless term M but also by the range of the dimensionless bulk substrate concentration ζb. The dependencies of the slope and the intercept on M and on the rate of ζb are shown graphically. Accurate estimations of M and the maximum velocity of the immobilized enzyme give the true, not apparent, Michaelis constant. It is shown that the linear correlations in the Lineweaver-Burk plots do not always coincide with the correlations for the estimation of M and the maximum velocity. It also is shown that large values of M may induce a serious error in the estimation of M with large values of ζb and in an estimation of the maximum velocity with small values of ζb. 相似文献
90.