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21.
In the search for candidate genes for the tuberous sclerosis (TSC1) disease locus on chromosome 9q34, we have isolated an overlapping series of 22 plasmid and phage cDNA clones covering nearly 7 kb and with an open reading frame of 5070 bp encoding a protein of 1690 amino acids. The putative protein product is a member of the kinesin superfamily and is homologous to the mouse KIF1A and theCaenorhabditas elegansunc-104 genes. Both KIF1A and unc-104 function in the anterograde axonal transport of synaptic vesicles. The human homolog is therefore termed H-ATSV (axonal transporter of synaptic vesicles, HGMW-approved nomenclature ATSV) Screening of DNA from 107 tuberous sclerosis patients and 80 unaffected individuals with H-ATSV cDNA probes by pulsed-field gel electrophoresis/Southern blotting following digestion by rare-cutting methylation-sensitive restriction enzymes showed variant banding patterns in three patients with tuberous sclerosis. However, further analysis indicated that these variant fragments represent a rare polymorphism probably associated with methylation of clustered restriction sites. There is no evidence to support H-ATSV as a candidate gene for TSC1. 相似文献
22.
The distribution of neurons containing NADPH-diaphorase (NADPH-d) activity and nitric oxide synthase-like immunoreactivity (NOS-LI) in the canine pyloric and ileocolonic sphincters was studied. Cells within the myenteric and submucosal ganglia were positive for NADPH-d. These cells generally had the morphology of Dogiel type-I enteric neurons, however, there was some diversity in the morphology of NADPH-d-positive neurons in the myenteric plexus of the pylorus. Intramuscular ganglia were observed in both sphincters, and NADPH-d was found in a sub-population of neurons within these ganglia. Dual staining with an antiserum raised against nitric oxide synthase (NOS) demonstrated that almost all cells with NOS-LI were also NADPH-d positive. Varicose fibers within ganglia and within the circular and longitudinal muscle layers also possed NOS-LI and NADPH-d activity. Dual staining with anti-VIP antibodies showed that some of the NADPH-d-positive cells in the myenteric and submucosal ganglia also contained VIP-LI, but all VIP-LI-positive cells did not express NADPH-d activity. These data are consistent with recent physiological studies suggesting that nitric oxide serves as an inhibitory neurotransmitter in the pyloric and ileocolonic sphincters. The data also suggest that VIP is expressed in a sub-population of NADPH-d-positive neurons and may therefore act as a co-transmitter in enteric inhibitory neurotransmission to these specialized muscular regions. 相似文献
23.
Evidence for natural horizontal transfer of tetQ between bacteria that normally colonize humans and bacteria that normally colonize livestock. 总被引:8,自引:1,他引:7 下载免费PDF全文
Though numerous studies have shown that gene transfer occurs between distantly related bacterial genera under laboratory conditions, the frequency and breadth of horizontal transfer events in nature remain unknown. Previous evidence for natural intergeneric transfers came from studies of genes in human pathogens, bacteria that colonize the same host. We present evidence that natural transfer of a tetracycline resistance gene, tetQ, has occurred between bacterial genera that normally colonize different hosts. A DNA sequence comparative approach was taken to examine the extent of horizontal tetQ dissemination between species of Bacteroides, the predominant genus of the human colonic microflora, and between species of Bacteroides and of the distantly related genus Prevotella, a predominant genus of the microflora of the rumens and intestinal tracts of farm animals. Virtually identical tetQ sequences were found in a number of isolate pairs differing in taxonomy and geographic origin, indicating that extensive natural gene transmission has occurred. Among the exchange events indicated by the evidence was the very recent transfer of an allele of tetQ usually found in Prevotella spp. to a Bacteroides fragilis strain. 相似文献
24.
Intermediates of adeno-associated virus type 2 (AAV) DNA replication in an in vitro assay have been characterized. The assay involves rescue and replication of an AAV insert in pBR322. Intermediates were shown to be duplex molecules in which at least one terminus was in the extended configuration, in contrast to the hairpinned ends seen after rescue in the absence of AAV DNA replication. Also present were linear double-stranded dimers, which were characterized as either head-to-head or tail-to-tail tandems; no head-to-tail dimers were detected. The results are in accord with the current model of AAV DNA replication. 相似文献
25.
Tokio Kogoma Kathryn G. Barnard Xiankang Hong 《Molecular & general genetics : MGG》1994,244(5):557-562
Constitutive stable DNA replication (cSDR), which uniquely occurs inEscherichia coli rnhA mutants deficient in ribonuclease HI activity, requires RecA function. TherecA428 mutation, which inactivates the recombinase activity but imparts a constitutive coprotease activity, blocks cSDR inrnhA mutants. The result indicates that the recombinase activity of RecA, which promotes homologous pairing and strand exchange, is essential for cSDR. Despite the requirement for RecA recombinase activity, mutations inrecB, recD, recJ, ruvA andruvC neither inhibit nor stimulate cSDR. It was proposed that the property of RecA essential for homologous pairing and strand exchange is uniquely required for initiation of cSDR inrnhA mutants without involving the homologous recombination process. The possibility that RecA protein is necessary to counteract the action of Tus protein, a contra-helicase which stalls replication forks in theter region of the chromosome, was ruled out because introduction of thetus : :kan mutation, which inactivates Tus protein, did not alleviate the RecA requirement for cSDR. 相似文献
26.
27.
Emmanuel Katsanis Maria A. Bausero Hong Xu Paul J. Orchard Zhiyi Xu R. Scott Melvor Adrienne A. Brian Bruce R. Blazar 《Cancer immunology, immunotherapy : CII》1994,38(2):135-141
We determined the expression of intercellular adhesion molecules (ICAM) on neuro-2a cells in order to evaluate whether they were involved in cytolysis of murine neuroblastoma. Fluorescence-activated cell sorting analysis revealed that the control neomycin-resistance-genetransduced line (neuro-2a/LN) had poor expression of ICAM-1 (mean channel fluorescence, MCF=3.7). An ICAM-1-positive transfectant of neuro-2a (neuro-2a/ICAM-1+) (CMF=64.3) was generated to evaluate directly the role of this adhesion molecule in cytolysis. Neuro-2a/ICAM-1+ was more sensitive to LAK killing (69.7% at an effector-to-target ratio of 1001) compared to neuro-2a/LN (48.6%) (P<0.001). Blocking of neuro-2a/LN and neuro-2a/ICAM-1+ lysis with anti-ICAM-1 monoclonal antibodies (mAbs) did not account for all the LFA-1-dependent killing. These data indicate that even in neuro-2a/ICAM-1+ cells, other LFA-1 ligands participated in the effector-target interaction. Therefore, we examined these cell lines for ICAM-2 expression. Both neuro-2a/LN and neuro-2a/ICAM-1+ lines expressed ICAM-2 (MCF=16.4 and 16.5). ICAM-2 accounted for the majority of the LFA-1-dependent killing in the ICAM-1-negative target, neuro-2a/LN, while ICAM-1 played a primary role in the cytolysis of the ICAM-1+ transfectant. Inhibition of lysis in the presence of anti-ICAM-1 and ICAM-2 mAbs was comparable to that seen with the addition of anti-LFA-1 mAb, indicating that other LFA-1 ligands were not involved in this system. ICAM-1 expression was associated with decreased in vivo tumorigenicity; mice inoculated with neuro-2a/ICAM-1+ cells had a significantly longer survival compared to those receiving neuro-2a/LN cells (median survival time 35.5 versus 24.5 days) (P<0.001). It is important to note that ICAM-1 transfection of murine neuroblastoma did not alter its metastatic potential. We conclude that transfection of mouse neuroblastome with ICAM-1 increases its sensitivity to in vitro lysis and reduces its in vivo tumorgenicity. In ICAM-1-negative murine neuroblastoma cells, ICAM-2 plays a primary role in cell-mediated lysis.This work was supported in part by the Children's Cancer Research Fund, the Minnesota Medical Foundation, the Viking Children's Fund and NIH grants PO1-CA-21737, NO1-AI-85002. E. K. is a recipient of the Irvine McQuarrie Research Scholar Award and B. R. B. a recipient of the Edward Mallinkrodt Foundation Scholar Award 相似文献
28.
滇蜀豹子花核型及其变异研究 总被引:7,自引:1,他引:6
本文详细报道了滇蜀豹子花的核型,发现居群中存在两种细胞型,即A型和B型。A型参考核型为2n = 24=2m(2SAT)+2sm+8st(4SAT)+12t(2SAT),其第3号两条同源染色体长臂均无居间随体:B型参考核型为2n=24=2m(2SAT)+2sm+8st(2SAT)+12t(3SAT)+0—1b,其第3号一条同源染色体长臂紧靠着丝点处有一大而明显的居间随体,而另一条同源染色体则无,构成明显的3号染色体的结构杂合性。统计表明,居群中二者的比例近似为1A;2B。研究还发现了大量的体细胞染色体结构变异核型,表明滇蜀豹子花核型尚未趋于稳定,还处于强烈分化之中,高频率的体细胞染色体结构变异是其种内分化不可忽视的一种进化要素。 相似文献
29.
油松鳞叶中细胞核穿壁现象的初步研究 总被引:1,自引:0,他引:1
利用薄切片和超薄切片技术对油松衰老鳞叶中细胞核穿壁运动进行了观察研究。首次,细胞核内的染色质逐渐收缩集中,形成染色深的球状体,以后,细胞核逐渐与细胞壁接近。接着紧贴细胞壁的细胞核通过细胞壁上的通道或胞间连丝转移到相邻的细胞内,此外,还发现有多种其它的转移方式存在。研究结果表明细胞核的穿壁运动现象同时存在于连子植物和裸植物中,电镜观察进一步证明细胞壁道在细胞核穿壁之前已形成。 相似文献
30.