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111.
A new, tenth subunit of TFIIH is responsible for the DNA repair syndrome trichothiodystrophy group A 总被引:21,自引:0,他引:21
112.
113.
数学分析是高等学校数学专业的一门重要基础课。在数学分析课的教学中实施分层教学,有利于调动学生的学习积极性、因材施教。本文提出了针对年招生量在100人左右的普通高等学校数学专业中,实施班内分层教学的必要性、操作方法和若干思考。 相似文献
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Repping S Skaletsky H Brown L van Daalen SK Korver CM Pyntikova T Kuroda-Kawaguchi T de Vries JW Oates RD Silber S van der Veen F Page DC Rozen S 《Nature genetics》2003,35(3):247-251
Many human Y-chromosomal deletions are thought to severely impair reproductive fitness, which precludes their transmission to the next generation and thus ensures their rarity in the population. Here we report a 1.6-Mb deletion that persists over generations and is sufficiently common to be considered a polymorphism. We hypothesized that this deletion might affect spermatogenesis because it removes almost half of the Y chromosome's AZFc region, a gene-rich segment that is critical for sperm production. An association study established that this deletion, called gr/gr, is a significant risk factor for spermatogenic failure. The gr/gr deletion has far lower penetrance with respect to spermatogenic failure than previously characterized Y-chromosomal deletions; it is often transmitted from father to son. By studying the distribution of gr/gr-deleted chromosomes across the branches of the Y chromosome's genealogical tree, we determined that this deletion arose independently at least 14 times in human history. We suggest that the existence of this deletion as a polymorphism reflects a balance between haploid selection, which culls gr/gr-deleted Y chromosomes from the population, and homologous recombination, which continues to generate new gr/gr deletions. 相似文献
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117.
Evidence for the formation of heteromultimeric potassium channels in Xenopus oocytes 总被引:23,自引:0,他引:23
Potassium channels show a wide range of functional diversity. Nerve cells typically express a number of K+ channels that differ in their kinetics, single-channel conductance, pharmacology, and sensitivity to voltage and second messengers. The cloning of the Shaker gene in Drosophila, and of related genes, has revealed that the encoded K+ channel polypeptides resemble one of the four internally homologous domains of the alpha-subunits of Na+ channels and Ca2+ channels, indicating that K+ channels may form by the co-assembly of several polypeptides. In this report we provide evidence that the Shaker A-type K+ channels expressed in Xenopus oocytes contain several Shaker polypeptides, that heteromultimeric channels may form through assembly of different channel polypeptides, that the kinetics or pharmacology of some heteromultimeric channels differ from those of homomultimeric channels, and that channel polypeptides from the fruit fly can co-assemble with homologous polypeptides from the rat. We suggest that heteromultimer formation may increase K+ channel diversity beyond even the level expected from the large number of K+ channel genes and alternative splicing products. 相似文献
118.
一类耦合方程组的初边值问题 总被引:1,自引:0,他引:1
张健 《四川师范大学学报(自然科学版)》1989,(1)
本文对一类复半线性 Schrdinger 方程和实半线性 Klein-Gordon 方程的耦合方程组分别具第一类边值条件和第二类边值条件的初边值问题,研究了其解的能量性质。我们首先对所讨论的问题引入一类能量积分,然后推导出能量不变式,并给出了所得能量不变式的初步应用. 相似文献
119.
Anske Van den Abbeele Sarah De Clercq Ariane De Ganck Veerle De Corte Berlinda Van Loo Sameh Hamdy Soror Vasundara Srinivasan Jan Steyaert Joël Vandekerckhove Jan Gettemans 《Cellular and molecular life sciences : CMLS》2010,67(9):1519-1535
RNA interference has tremendously advanced our understanding of gene function but recent reports have exposed undesirable
side-effects. Recombinant Camelid single-domain antibodies (VHHs) provide an attractive means for studying protein function without affecting gene expression.
We raised VHHs against gelsolin (GsnVHHs), a multifunctional actin-binding protein that controls cellular actin organization
and migration. GsnVHH-induced delocalization of gelsolin to mitochondria or the nucleus in mammalian cells reveals distinct
subpopulations including free gelsolin and actin-bound gelsolin complexes. GsnVHH 13 specifically recognizes Ca2+-activated gelsolin (K
d ~10 nM) while GsnVHH 11 binds gelsolin irrespective of Ca2+ (K
d ~5 nM) but completely blocks its interaction with G-actin. Both GsnVHHs trace gelsolin in membrane ruffles of EGF-stimulated
MCF-7 cells and delay cell migration without affecting F-actin severing/capping or actin nucleation activities by gelsolin.
We conclude that VHHs represent a potent way of blocking structural proteins and that actin nucleation by gelsolin is more
complex than previously anticipated. 相似文献
120.
Disrupted function and axonal distribution of mutant tyrosyl-tRNA synthetase in dominant intermediate Charcot-Marie-Tooth neuropathy 总被引:6,自引:0,他引:6
Jordanova A Irobi J Thomas FP Van Dijck P Meerschaert K Dewil M Dierick I Jacobs A De Vriendt E Guergueltcheva V Rao CV Tournev I Gondim FA D'Hooghe M Van Gerwen V Callaerts P Van Den Bosch L Timmermans JP Robberecht W Gettemans J Thevelein JM De Jonghe P Kremensky I Timmerman V 《Nature genetics》2006,38(2):197-202
Charcot-Marie-Tooth (CMT) neuropathies are common disorders of the peripheral nervous system caused by demyelination or axonal degeneration, or a combination of both features. We previously assigned the locus for autosomal dominant intermediate CMT neuropathy type C (DI-CMTC) to chromosome 1p34-p35. Here we identify two heterozygous missense mutations (G41R and E196K) and one de novo deletion (153-156delVKQV) in tyrosyl-tRNA synthetase (YARS) in three unrelated families affected with DI-CMTC. Biochemical experiments and genetic complementation in yeast show partial loss of aminoacylation activity of the mutant proteins, and mutations in YARS, or in its yeast ortholog TYS1, reduce yeast growth. YARS localizes to axonal termini in differentiating primary motor neuron and neuroblastoma cultures. This specific distribution is significantly reduced in cells expressing mutant YARS proteins. YARS is the second aminoacyl-tRNA synthetase found to be involved in CMT, thereby linking protein-synthesizing complexes with neurodegeneration. 相似文献