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排序方式: 共有846条查询结果,搜索用时 15 毫秒
41.
Molecular analysis of gene expression in the developing pontocerebellar projection system 总被引:7,自引:0,他引:7
Díaz E Ge Y Yang YH Loh KC Serafini TA Okazaki Y Hayashizaki Y Speed TP Ngai J Scheiffele P 《Neuron》2002,36(3):417-434
As an approach toward understanding the molecular mechanisms of neuronal differentiation, we utilized DNA microarrays to elucidate global patterns of gene expression during pontocerebellar development. Through this analysis, we identified groups of genes specific to neuronal precursor cells, associated with axon outgrowth, and regulated in response to contact with synaptic target cells. In the cerebellum, we identified a phase of granule cell differentiation that is independent of interactions with other cerebellar cell types. Analysis of pontine gene expression revealed that distinct programs of gene expression, correlated with axon outgrowth and synapse formation, can be decoupled and are likely influenced by different cells in the cerebellar target environment. Our approach provides insight into the genetic programs underlying the differentiation of specific cell types in the pontocerebellar projection system. 相似文献
42.
Intracellular pH regulatory mechanism in human atrial myocardium: functional evidence for Na(+)/H(+) exchanger and Na(+)/HCO(3)(-) symporter 总被引:1,自引:0,他引:1
Loh SH Chen WH Chiang CH Tsai CS Lee GC Jin JS Cheng TH Chen JJ 《Journal of biomedical science》2002,9(3):198-205
Intracellular pH (pH(i)) exerts considerable influence on cardiac contractility and rhythm. Over the last few years, extensive progress has been made in understanding the system that controls pH(i) in animal cardiomyocytes. In addition to the housekeeping Na(+)-H(+) exchanger (NHE), the Na(+)-HCO(3)(-) symporter (NHS) has been demonstrated in animal cardiomyocytes as another acid extruder. However, whether the NHE and NHS functions exist in human atrial cardiomyocytes remains unclear. We therefore investigated the mechanism of pH(i) recovery from intracellular acidosis (induced by NH(4)Cl prepulse) using intracellular 2',7'-bis(2-carboxethyl)-5(6)-carboxy-fluorescein fluorescence in human atrial myocardium. In HEPES (nominally HCO(3)(-)-free) Tyrode solution, pH(i) recovery from induced intracellular acidosis could be blocked completely by 30 microM 3-methylsulfonyl-4-piperidinobenzoyl, guanidine hydrochloride (HOE 694), a specific NHE inhibitor, or by removing extracellular Na(+). In 3% CO(2)-HCO(3)(-) Tyrode solution, HOE 694 only slowed the pH(i) recovery, while addition of HOE 694 together with 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (an NHS inhibitor) or removal of extracellular Na(+) inhibited the acid extrusion entirely. Therefore, in the present study, we provided evidence that two acid extruders involved in acid extrusion in human atrial myocytes, one which is HCO(3)(-) independent and one which is HCO(3)(-) dependent, are mostly likely NHE and NHS, respectively. When we checked the percentage of contribution of these two carriers to pH(i) recovery following induced acidosis, we found that the activity of NHE increased steeply in the acid direction, while that of NHS did not change. Our present data indicate for the first time that two acid extruders, NHE and NHS, exist functionally and pH(i) dependently in human atrial cardiomyocytes. 相似文献
43.
Magbanua FO Natividad KT Migo VP Alfafara CG de la Peña FO Miranda RO Albaladejo JD Nadala EC Loh PC Mahilum-Tapay L 《Diseases of aquatic organisms》2000,42(1):77-82
The prevalence and geographic distribution of white spot syndrome virus (WSSV) infection among cultured penaeid shrimp in the Philippines was determined from January to May, 1999, using PCR (polymerase chain reaction) protocol and Western blot assays. A total of 71 samples consisting of 18 post-larvae (PL) and 53 juvenile/adult shrimp samples (56 to 150 days-of-culture, DOC) were screened for WSSV. Of the 71 samples tested, 51 (72%) were found positive for WSSV by PCR: 61% (31/51) after 1-step PCR and 39% (20/51) after 2-step, non-nested PCR. Of the PL and juvenile/adult shrimp samples tested, 50 and 79% were positive for WSSV, respectively. By Western blot, only 6 of the 51 (12%) PCR-positive samples tested positive for WSSV. Of the 20 samples negative for WSSV by PCR, all tested negative for WSSV by Western blot assay. This is the first report of the occurrence of WSSV in the Philippines. 相似文献
44.
Amplified fragment length polymorphism fingerprinting of 16 banana cultivars (Musa cvs.) 总被引:4,自引:0,他引:4
Banana is one of the most important subtropical crops. The genetic system, however, is relatively unknown and is complicated by specific interhybridization, heterozygosity, and polyploidy, which are common in most clones. These factors make identification of closely related banana cultivars difficult, particularly when sterile. Amplified fragment length polymorphism (AFLP) analysis using eight primer combinations was carried out on 16 banana cultivars. Results showed that AFLP could be used to distinguish the different cultivars by their unique banding patterns. Unique AFLP molecular markers were detected for 12 banana cultivars, which can be used to develop specific probes for identification purposes. The cluster analysis also revealed the need for a link between genotype studies using molecular techniques and the current system of classification of Musa cultivars based purely on morphological traits. 相似文献
45.
Nellie Y. Loh Helen J. Ambrose Lisa M. Guay-Woodford Srimita DasGupta Ralph A. Nawrotzki Derek J. Blake Kay E. Davies 《Mammalian genome》1998,9(11):857-862
β-Dystrobrevin, a dystrophin-related protein that is expressed in non-muscle tissues, is highly homologous to α-dystrobrevin,
a member of the dystrophin-associated protein complex (DPC). β-Dystrobrevin associates with Dp71 and syntrophin and is believed
to have a role in non-muscle DPCs. Here we report the characterization and mapping of the mouse β-dystrobrevin gene. The mouse
β-dystrobrevin gene is organized into 21 exons spanning over 130 kb of DNA. We provide evidence that this gene is transcribed
from at least two promoter regions but appears to utilize a common translation initiation site. We show that the similarity
between β-dystrobrevin and α-dystrobrevin is reflected in the conservation of their exon-intron junctions. β-Dystrobrevin
has been localized to proximal mouse Chromosome (Chr) 12 by backcross mapping. A database search revealed that two mouse genetic
diseases involving tissues expressing β-dystrobrevin have been mapped to this region, namely, congenital polycystic kidneys
(cpk) and fatty liver dystrophy (fld). However, refined mapping analysis has excluded β-dystrobrevin as a candidate gene for either disease.
Received: 1 June 1998 / Accepted: 16 July 1998 相似文献
46.
Dhanvantari S Shen FS Adams T Snell CR Zhang C Mackin RB Morris SJ Loh YP 《Molecular endocrinology (Baltimore, Md.)》2003,17(9):1856-1867
In familial hyperproinsulinemia, specific mutations in the proinsulin gene are linked with a profound increase in circulating plasma proinsulin levels. However, the molecular and cellular basis for this disease remains uncharacterized. Here we investigated how these mutations may disrupt the sorting signal required to target proinsulin to the secretory granules of the regulated secretory pathway, resulting in the unregulated release of proinsulin. Using a combination of molecular modeling and site-directed mutagenesis, we have identified structural molecular motifs in proinsulin that are necessary for correct sorting into secretory granules of endocrine cells. We show that membrane carboxypeptidase E (CPE), previously identified as a prohormone-sorting receptor, is essential for proinsulin sorting. This was demonstrated through short interfering RNA-mediated depletion of CPE and transfection with a dominant negative mutant of CPE in a beta-cell line. Mutant proinsulins found in familial hyperproinsulinemia failed to bind to CPE and were not sorted efficiently. These findings provide evidence that the elevation of plasma proinsulin levels found in patients with familial hyperproinsulinemia is caused by the disruption of CPE-mediated sorting of mutant proinsulins to the regulated secretory pathway. 相似文献
47.
Abstract: Chronic etorphine treatment of neuroblastoma × glioma NG108-15 cells results in both an increase in adenylate cyclase activity (upon addition of the opiate antagonist naloxone) as well as an homologous desensitization of the opiate receptor. The continued ability of opiate agonists to regulate adenylate cyclase activity following opiate receptor desensitization can be understood by proposing that the catalytic subunit of adenylate cyclase in NG108-15 cells is under tonic regulation by both guanine nucleotide regulatory (Ni ) and stimulatory (Ns ) components. Inactivation of Ni by pertussis toxin (PT) treatment resulted in elevated adenylate cyclase activities comparable to those observed in control cells following chronic opiate treatment. This increased enzymatic activity could not be further induced by PT treatment of cells exposed to opiate previously. In addition, procedures that prevented receptor-mediated activation of Ns , i.e., treatment with NaF or desensitization of the stimulatory receptors (prostaglandin E1 , adenosine) eliminated the increase in adenylate cyclase activity induced by naloxone following chronic opiate exposure. Hence, the increase in enzymatic activity observed following chronic opiate treatment may be due to a loss in tonic inhibitory regulation of adenylate cyclase mediated through Ni resulting in the unimpeded expression of Ns activity. This tonic inhibition of adenylate cyclase activity is one of the multiple mechanisms by which Ni regulates adenylate cyclase in this cell line. 相似文献
48.
Elucidating the phylogenetic relationships of the current but problematic Dasyatidae (Order Myliobatiformes) was the first priority of the current study. Here, we studied three molecular gene markers of 43 species (COI gene), 33 species (ND2 gene) and 34 species (RAG1 gene) of stingrays to draft out the phylogenetic tree of the order. Nine character states were identified and used to confirm the molecularly constructed phylogenetic trees. Eight or more clades (at different hierarchical level) were identified for COI, ND2 and RAG1 genes in the Myliobatiformes including four clades containing members of the present Dasyatidae, thus rendering the latter non-monophyletic. The uncorrected p-distance between these four ‘Dasytidae’ clades when compared to the distance between formally known families confirmed that these four clades should be elevated to four separate families. We suggest a revision of the present classification, retaining the Dasyatidae (Dasyatis and Taeniurops species) but adding three new families namely, Neotrygonidae (Neotrygon and Taeniura species), Himanturidae (Himantura species) and Pastinachidae (Pastinachus species). Our result indicated the need to further review the classification of Dasyatis microps. By resolving the non-monophyletic problem, the suite of nine character states enables the natural classification of the Myliobatiformes into at least thirteen families based on morphology. 相似文献
49.
50.
Sing-Huang Tan Nur Sabrina Sapari Hui Miao Mikael Hartman Marie Loh Wee-Joo Chng Philip Iau Shaik Ahmad Buhari Richie Soong Soo-Chin Lee 《PloS one》2015,10(12)