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排序方式: 共有930条查询结果,搜索用时 15 毫秒
1.
Fei Mi Ying Zhang Dan Yang Xiaozhao Tang Pengfei Wang Xiaoxia He Yunrun Zhang Jianyong Dong Yang Cao Chunli Liu Ke-Qin Zhang Jianping Xu 《PloS one》2016,11(2)
During the past 40 years, more than 400 Sudden Unexplained Deaths (SUDs) have occurred in Yunnan, southwestern China. Epidemiological and toxicological analyses suggested that a newly discovered mushroom called Trogia venenata was the leading culprit for SUDs. At present, relatively little is known about the genetics and natural history of this mushroom. In this study, we analyzed the sequence variation at four DNA fragments among 232 fruiting bodies of T. venenata collected from seven locations. Our ITS sequence analyses confirmed that all the isolates belonged to the same species. The widespread presence of sequence heterozygosity within many strains at each of three protein-coding genes suggested that the fruiting bodies were diploid, dikaryotic or heterokaryotic. Within individual geographic populations, we found significant deviations of genotype frequencies from Hardy-Weinberg expectations, with the overall observed heterozygosity lower than that expected under random mating, consistent with prevalent inbreeding within local populations. The geographic populations were overall genetically differentiated. Interestingly, while a positive correlation was found between population genetic distance and geographic distance, there was little correlation between genetic distance and barium concentration difference for the geographic populations. Our results suggest frequent inbreeding, geographic structuring, and limited gene flow among geographic populations of T. venenata from southwestern China. 相似文献
2.
Jianyong Wu 《Cytotechnology》1996,22(1-3):103-109
Animal cells in suspension culture can suffer severe mechanical damage from bursting gas bubbles or other hydrodynamic force sources. Certain chemical additives in the culture media, particularly some surface-active chemicals, can effectively protect animal cells against such damage. Previously we proposed that the protective effect is associated with the adsorption of the additives in the cell membrane through hydrophobic binding of the surface-active molecules to the membrane. Adsorption of the additives to the cell membrane may lead to decreased hydrophobicity of the cell surface, thus eliminating cell adhesion to bubbles and reducing cell damage from bursting bubbles. In this study, we measured the hydrophobicity of two insect cell lines based on cell adhesion to hydrocarbon phase and its influence by surface-active chemicals, Pluronic F68, a methylcellulose and a polyethylene glycol. The experimental results showed strong support for the aforecited cell protection mechanism. 相似文献
3.
Tissue plasminogen activator (tPA) has been implicated in neurite outgrowth and neurological recovery post stroke. tPA converts the zymogen plasminogen (Plg) into plasmin. In this study, using plasminogen knockout (Plg-/-) mice and their Plg-native littermates (Plg+/+), we investigated the role of Plg in axonal remodeling and neurological recovery after stroke. Plg+/+ and Plg-/- mice (n = 10/group) were subjected to permanent intraluminal monofilament middle cerebral artery occlusion (MCAo). A foot-fault test and a single pellet reaching test were performed prior to and on day 3 after stroke, and weekly thereafter to monitor functional deficit and recovery. Biotinylated dextran amine (BDA) was injected into the left motor cortex to anterogradely label the corticospinal tract (CST). Animals were euthanized 4 weeks after stroke. Neurite outgrowth was also measured in primary cultured cortical neurons harvested from Plg+/+ and Plg-/- embryos. In Plg+/+ mice, the motor functional deficiency after stroke progressively recovered with time. In contrast, recovery in Plg-/- mice was significantly impaired compared to Plg+/+ mice (p<0.01). BDA-positive axonal density of the CST originating from the contralesional cortex in the denervated side of the cervical gray matter was significantly reduced in Plg-/- mice compared with Plg+/+ mice (p<0.05). The behavioral outcome was highly correlated with the midline-crossing CST axonal density (R2>0.82, p<0.01). Plg-/- neurons exhibited significantly reduced neurite outgrowth. Our data suggest that plasminogen-dependent proteolysis has a beneficial effect during neurological recovery after stroke, at least in part, by promoting axonal remodeling in the denervated spinal cord. 相似文献
4.
Nodal cuttings of white yam were induced to produce microtubers on a MS-revised medium supplemented with various concentrations of sucrose, 20 mgl–1 L-cysteine, 0.5 mgl–1 kinetin and 0.7% agar. The frequency of tuberization was affected by the daylength, which is optimal at 12 and 16 h of light depending on the sucrose concentration. The microtubers were planted in a seed bed and grown to maturity. The importance of in vitro tuberization of yam as a means of international germplasm distribution or exchange as well as for the propagation of planting material is discussed. 相似文献
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从嗜热蓝藻优雅粘囊藻(Myxosarcina concinna Printz.)中分离到具有放氧活性的藻胆体-类囊体膜复合物。它的吸收峰位于680、628、490、438和420 nm ,在低离子强度(0.1~0.4 m ol/L)磷酸缓冲液中的664 nm 荧光发射峰随离子强度的降低而升高,718 nm 荧光发射峰与此相反(77 。K,Ex= 580 nm )。当把游离的藻胆体和已解离去藻胆体的类囊体膜在蔗糖磷酸缓冲液中重组时,随时间延长(0~60 m in),718 nm 荧光发射峰逐渐升高,685 nm 荧光发射峰逐渐下降(77 。K,Ex = 580 nm ),表明藻胆体与类囊体之间的解离和结合对光能传递的影响 相似文献
7.
APC基因是1991年被发现的一类肿瘤抑制基因,它被定位于人第5号染色体5q21处。APC基因如发生缺失或突变,则易患直肠肿瘤,并伴有部分先天痴呆的病例。本工作在孟帆已获得的APC基因在豚鼠中的同源cDNA的基础上,完成了对它的亚克隆,并利用原位杂交和RNA酶保护分析的方法,对它在脑中的分布进行了研究。发现APCmRNA主要在海马、大脑和小脑中表达;嗅球中杂交信号稍弱,脑干中最弱。海马中阳性细胞主要是锥体细胞,小脑中则主要是内层颗粒细胞。在一个月大的豚鼠胚胎的脑中也观察到相似的表达型式。进一步的研究有助于我们更好地了解神经发育和先天痴呆发生的分子机制。 相似文献
8.
野生大豆种子蛋白含量差异的生理及结构基础的探讨 总被引:1,自引:0,他引:1
利用SDS-聚丙烯酰胺凝胶电泳、电子显微镜、蛋白及酰脲含量测定等技术,对高蛋白含量(50.7% )的50359 和低蛋白含量(40.8% )的50305 两个野生大豆在种子发育过程中贮藏蛋白积累的速率、蛋白组分合成的起始时间、蛋白体发育的进程以及幼茎的酰脲含量进行了比较研究。结果表明:野生大豆50359的高蛋白含量是与其种子发育过程中较高的植株酰脲含量、较早较快的贮藏蛋白合成及积累速率,液泡中高效的蛋白贮藏方式以及蛋白体在子叶细胞中占有较大体积相联系的 相似文献
9.
本文用ABC—GDN免疫组织化学方法,研究了γ-氨基丁酸(Gamma—Aminobutyric Acid,GABA)在大鼠胰腺的定位和分布,并用相邻切片法,观察它与胰岛素的共存关系。结果发现GABA免疫反应阳性细胞主要分布于胰腺内分泌部(胰岛)。在外分泌部亦有少许分布。大部分胰岛细胞呈GABA免疫反应阳性,集中位于胰岛的中央部。相邻连续切片免疫染色证实GABA与胰岛素共存于胰岛B细胞中。外分泌部胰腺GABA免疫反应阳性细胞,呈零散分布于腺泡和导管上皮间。本文为进一步探讨GABA在胰腺的生理作用提供了形态学依据。 相似文献
10.
Yutong Wang Xu Yan Mei Xu Weiyang Qi Chunjie Shi Xiaohong Li Jiaqi Ma Dan Tian Jianxin Shou Haijun Wu Jianwei Pan Bo Li Chao Wang 《植物学报(英文版)》2023,65(1):82-99
Clathrin-mediated endocytosis (CME) is the major endocytic pathway in eukaryotic cells that directly regulates abundance of plasma membrane proteins. Clathrin triskelia are composed of clathrin heavy chains (CHCs) and light chains (CLCs), and the phytohormone auxin differentially regulates membrane-associated CLCs and CHCs, modulating the endocytosis and therefore the distribution of auxin efflux transporter PIN-FORMED2 (PIN2). However, the molecular mechanisms by which auxin regulates clathrin are still poorly understood. Transmembrane kinase (TMKs) family proteins are considered to contribute to auxin signaling and plant development; it remains unclear whether they are involved in PIN transport by CME. We assessed TMKs involvement in the regulation of clathrin by auxin, using genetic, pharmacological, and cytological approaches including live-cell imaging and immunofluorescence. In tmk1 mutant seedlings, auxin failed to rapidly regulate abundance of both CHC and CLC and to inhibit PIN2 endocytosis, leading to an impaired asymmetric distribution of PIN2 and therefore auxin. Furthermore, TMK3 and TMK4 were shown not to be involved in regulation of clathrin by auxin. In summary, TMK1 is essential for auxin-regulated clathrin recruitment and CME. TMK1 therefore plays a critical role in the establishment of an asymmetric distribution of PIN2 and an auxin gradient during root gravitropism. 相似文献