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981.
Zhong-Qiang Chen Jinnan Tong Margaret L. Fraiser 《Palaeogeography, Palaeoclimatology, Palaeoecology》2011,299(3-4):449-474
Unlike the high-abundance, low-diversity macrofaunas that characterize many Early Triassic benthic palaeocommunities, ichnofossils were relatively common in the aftermath of the end-Permian mass extinction worldwide. Ichnofossils therefore are a good proxy for ecosystem recovery after the end-Permian biotic crisis. This paper documents 14 ichnogenera and one problematic form from Lower Triassic successions exposed in the Lower Yangtze region, South China. Post-extinction ichnodiversity remained rather low throughout the Griesbachian–early Smithian period and abruptly increased in the late Smithian. However, several lines of evidence, including extent of bioturbation, burrow size, trace-fossil complexity, and tiering levels, indicate that diversification of ichnotaxa in the late Smithian did not signal full marine ecosystem recovery from the Permian/Triassic (P/Tr) mass extinction. Marine ichnocoenoses did not recover until the late Spathian in South China. The marginal sea provided hospitable habitats for tracemakers to proliferate in the aftermath of the end-Permian mass extinction. 相似文献
982.
983.
Zhou Q Wang L Cai X Wang D Hua X Qu L Lin J Chen T 《Journal of plant physiology》2011,168(11):1249-1255
Casparian bands of endodermis and exodermis play crucial roles in blocking apoplastic movement of ions and water into the stele of roots through the cortex. These apoplastic barriers differ considerably in structure and function along the developing root. The present study assessed net Na+ fluxes in anatomically distinct root zones of rice seedlings and analyzed parts of individual roots showing different Na+ uptake. The results indicated that anatomically distinct root zones contributed differently to the overall uptake of Na+. The average Na+ uptake in root zones in which Casparian bands of the endo- and exo-dermis were interrupted by initiating lateral root primordia (root zone III) was significantly greater than that at the root apex, where Casparian bands were not yet formed (root zone I), or in the region where endo- and exo-dermis with Casparian bands were well developed (root zone II). The measurement of net Na+ fluxes using a non-invasive scanning ion-selective electrode technique (SIET) demonstrated that net Na+ flux varied significantly in different positions along developing rice roots, and a net Na+ influx was obvious at the base of young lateral root primordia. Since sodium fluxes changed significantly along developing roots of rice seedlings, we suggest that the significantly distinct net Na+ flux profile may be attributed to different apoplastic permeability due to lateral root primordia development for non-selective apoplastic bypass of ions along the apoplast. 相似文献
984.
Dental caries is a common oral bacterial infectious disease of global concern. Prevention and treatment of caries requires control of the dental plaque formed by pathogens such as Streptococcus mutans and Streptococcus sobrinus. Pleurocidin, produced by Pleuronectes americanus, is an antimicrobial peptide that exerts broad-spectrum activity against pathogenic bacteria and fungi. Moreover, pleurocidin shows less hemolysis and is less toxic than other natural peptides. In the present study, we investigated whether pleurocidin is an effective antibiotic peptide against common cariogenic microorganisms and performed a preliminary study of the antimicrobial mechanism. We assayed minimal inhibitory concentration (MIC), minimal bactericide concentration (MBC) and bactericidal kinetics and performed a spot-on-lawn assay. The BioFlux system was used to generate bacterial biofilms under controllable flow. Fluorescence microscopy and confocal laser scanning microscopy (CLSM) were used to analyze and observe biofilms. Scanning electron microscopy was used to observe the bacterial membrane. MIC and MBC results showed that pleurocidin had different antimicrobial activities against the tested oral strains. Although components of saliva could affect antimicrobial activity, pleurocidin dissolved in saliva still showed antimicrobial effects against oral microorganisms. Furthermore, pleurocidin showed a favorable killing effect against BioFlux flow biofilms in vitro. Our findings suggest that pleurocidin has the potential to kill dental biofilms and prevent dental caries. 相似文献
985.
Since its discovery, many physiologic functions have been ascribed to ghrelin, a gut derived hormone. The presence of a median fatty acid side chain on the ghrelin peptide is required for the binding and activation of the classical ghrelin receptor, the growth hormone secretagogue receptor (GHSR)-1a. Ghrelin O-acyl transferase (GOAT) was recently discovered as the enzyme responsible for this acylation process. GOAT is expressed in all tissues that have been found to express ghrelin and has demonstrated actions on several complex endocrine organ systems such as the hypothalamus-pituitary-gonadal, insular and adrenal axis as well as the gastrointestinal (GI) tract, bone and gustatory system. Ghrelin acylation is dependent on the function of GOAT and the availability of substrates such as proghrelin and short- to medium-chain fatty acids (MCFAs). This process is governed by GOAT activity and has been shown to be modified by dietary lipids. In this review, we provided evidence that support an important role of GOAT in the regulation of energy homeostasis and glucose metabolism by modulating acyl ghrelin (AG) production. The relevance of GOAT and AG during periods of starvation remains to be defined. In addition, we summarized the recent literature on the metabolic effects of GOAT specific inhibitors and shared our view on the potential of targeting GOAT for the treatment of metabolic disorders such as obesity and type 2 diabetes. 相似文献
986.
PEG1基因影响动物胚胎生长及母性行为,多数动物PEG1为父方表达的遗传印记特征,但出生后猪的PEG1印记表达尚不清楚。因此,文章选取长白、大白和蓝塘3个品种共166头纯种猪,在猪的PEG1基因外显子12区域内寻找SNP,采用PCR-SSCP方法对其多态性进行检测和基因频率分析;取带有PEG1基因该位点SNP为杂合的仔猪3头,对其胃、胸腺、胰、脾、肺、肌肉、肝、舌、肾、脑、膀胱、心脏等组织器官和胎盘的mRNA产物分别进行RT-PCR-SSCP分析,结果表明:PEG1基因外显子12存在一个由G突变为A的单核苷酸多态性位点;PEG1的外显子12在3头仔猪的主要组织器官仅表达父亲来源的等位基因,表明猪的PEG1基因呈母方印记、父方表达的遗传特征。 相似文献
987.
Peng X Gong F Xie G Zhao Y Tang M Yu L Tong A 《Molecular and cellular biochemistry》2011,351(1-2):233-241
This study aimed to explore the mechanism of adriamycin resistance in human chronic myelogenous leukemia cells. Proteomic approach was utilized to compare and identify differentially expressed proteins between human chronic myelogenous leukemia K562 cells and their adriamycin-resistant counterparts. The differentially expressed proteins were analyzed by 2-DE (two-dimensional gel electrophoresis), and protein identification were performed on ESI-Q-TOF MS/MS instrument. Out of the 35 differentially expressed proteins between the two cell lines, 29 were identified and grouped into 10 functional classes. Most of identified proteins were related to the categories of metabolism (24%), proteolysis (13%), signal transduction (21%) and calcium ion binding (6%), suggesting that alterations of those biological processes might be involved in adriamycin resistance of K562 cells. We believe this study may provide some clues to a better understanding of the molecular mechanisms underlying adriamycin resistance. 相似文献
988.
Kong F Tong R Jia L Wei W Miao X Zhao X Sun W Yang G Zhao C 《Molecular and cellular biochemistry》2011,354(1-2):199-205
OVCA1, a tumor suppressor gene, is deleted or lower expressed in about 80% of ovarian cancer. Over expression of OVCA1 in human ovarian cancer A2780 cells inhibits cell proliferation and arrests cells in G1 stage. However, the fact that the molecular mechanism of OVCA1 inhibits cell growth is presently elusive. Here we investigated the potential signaling pathway induced by over-expression of OVCA1. Our results show that over-expression of human OVCA1 in ovarian cancer cells A2780 leads to down-regulation of cyclin D1, and up-regulation of p16, but no effect on the expression of NF-κB. It indicates that OVCA1 could inhibit the proliferation of ovarian cancer cell A2780 by p16/cyclin D1 pathway, but not by NF-κB. 相似文献
989.
In the budding yeast Saccharomyces cerevisiae, the structure and function of telomeres are maintained by binding proteins, such as Cdc13-Stn1-Ten1 (CST), Yku, and the telomerase complex. Like CST and Yku, telomerase also plays a role in telomere protection or capping. Unlike CST and Yku, however, the underlying molecular mechanism of telomerase-mediated telomere protection remains unclear. In this study, we employed both the CDC13-EST1 fusion gene and the separation-of-function allele est1-D514A to elucidate that Est1 provided a telomere protection pathway that was independent of both the CST and Yku pathways. Est1's ability to convert single-stranded telomeric DNA into a G quadruplex was required for telomerase-mediated telomere protection function. Additionally, Est1 maintained the integrity of telomeres by suppressing the recombination of subtelomeric Y' elements. Our results demonstrate that one major functional role that Est1 brings to the telomerase complex is the capping or protection of telomeres. 相似文献
990.
Fan D Gu YT Lv H Tang T Xu ZH Song ZQ Tong XJ 《Cellular and molecular neurobiology》2011,31(8):1213-1219
This study was performed to investigate the mechanism of blood–brain barrier (BBB) permeability change, which was induced
by aminoguanidine (AG) after surgical brain injury (SBI) in rats. Compared to control group, AG (150 mg/kg, i.p.) significantly
reduced Evans blue extravasation into brain tissue at 24 h after surgical resection, it also induced a 32% decrease of malondialdehyde
(MDA) values and a 1.1-fold increase of the glutathione (GSH) levels at 12 h after injury. The expression of inducible nitric
oxide synthase (iNOS) reached the peak value at 24 h after SBI, which was significantly attenuated after AG treatment. In
addition, ZO-1 protein was up-regulated by AG (150 mg/kg) treatment at 24 h after SBI. Our results indicated that AG could
protect the BBB after SBI, which could be correlated with antioxidative property, the down-regulation of iNOS and up-regulation
of tight junction protein expression. 相似文献