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991.
Nuclear matrix (NM) and intermediate filament (IF) scaffold in primitive eukaryote Crypthecodinium cohnii were shown using selective extraction together with embedment-free electron microscopy, whole mount cell preparation and immunoblot techniques. There exists a delicate NM-IF network spreading over cytoplasm and nucleus in dinoflagellate cells, however, nuclear lamina is undeveloped. The diameter of NM fiber is about 3-5 nm and IF is 10 nm. Chromosomes are connected with NM filament network. Immunoblot analysis showed that dinoflagellate contained keratin-like polypeptides (63 kD and 67 kD) while mammalian lamin antibodies did not crossreact with dinoflagellate total protein. Our experiment results demonstrated that a framework similar to NM-IF scaffold in mammalian cell appeared in primitive eukaryote. We propose that: (1) NM-IF scaffold is not restrict to vertebrate cell, and it may be originated from early stages of eukaryote evolution; (2) Keratin is probably very conservative; (3) Compared with IF, lamina might appear late in evolution, and some of primitive characteristics of dinoflagellate nucleus may be related to the lack of lamina.  相似文献   
992.
抑郁症模型大鼠学习记忆能力变化研究   总被引:3,自引:0,他引:3  
为探讨抑郁症发生发展过程中学习记忆能力的变化模式及其可能机制.分别采用21天慢性非预见性刺激法和嗅球切除法建立的抑郁症模型大鼠.运用旷场行为实验(open—field behavior)检测大鼠主动性活动能力,用Morris水迷宫法检测大鼠空间学习记忆能力,HPLC—UV法测定大鼠血清皮质醇含量。电生理法记录海马CA1区LTP与LTD,观察海马神经元的突触可塑性。结果显示:与对照组相比,两种模型的自主活动性、空间探索兴趣和学习能力都明显降低,而记忆的反馈功能没有明显的变化。同时.两种模型大鼠海马神经细胞的突触可塑性显著下降,血清皮质醇的含量则明显上升。提示两种建模方法均导致大鼠产生抑郁症状和学习能力障碍.但对记忆反馈功能无明显影响。  相似文献   
993.
Although the current glucocorticoids (GCs) treatment for systemic lupus erythematosus (SLE) is effective to a certain extent, the difference in therapeutic effect between patients is still a widespread problem. Some patients can have repeated attacks that greatly diminish their quality of life. This study was conducted to investigate the relationship between HSP90AA2 polymorphisms and disease susceptibility, GCs efficacy and health-related quality of life (HRQoL) in Chinese SLE patients. A case–control study was performed in 470 SLE patients and 470 normal controls. Then, 444 patients in the case group were followed up for 12 weeks to observe efficacy of GCs and improvement of HRQoL. Two single nucleotide polymorphisms (SNPs) of HSP90AA2 were selected for genotyping: rs1826330 and rs6484340. HRQoL was assessed using the SF-36 questionnaire. The minor T allele of rs1826330 and the TT haplotype formed by rs1826330 and rs6484340 showed associations with decreased SLE risk (T allele: PBH?=?0.022; TT haplotype: PBH?=?0.033). A significant association between rs6484340 and improvement of HRQoL was revealed in the follow-up study. Five subscales of SF-36 were appeared to be influenced by rs6484340: total score of SF-36 (additive model: PBH?=?0.026), physical function (additive model: PBH?=?0.026), role-physical (recessive model: PBH?=?0.041), mental health (dominant model: PBH?=?0.047), and physical component summary (additive model: PBH?=?0.026). No statistical significance was found between HSP90AA2 gene polymorphisms and GCs efficacy. These results revealed a genetic association between HSP90AA2 and SLE. Remarkably, HSP90AA2 has an impact on the improvement of HRQoL in Chinese population with SLE.  相似文献   
994.
青龙河底栖无脊椎动物群落结构及其水质评价   总被引:14,自引:3,他引:14  
本文论述了青龙河底栖生物种类、数量、分布和结构等特点及其与环境因子间的关系。应用Beck、Gleason、Shannon、Simpson等生物指数对水质状况进行评价。结果表明青龙河除个别断面受污染外,大部分河段属尚清洁水。  相似文献   
995.
RNA干扰(RNA interference,RNAi)是指由双链RNA(double strand RNA,dsRNA)介导的序列特异的RNA降解过程。已经证明,在植物和昆虫细胞中RNAi是其主要的抗病毒免疫机制,至今为止几乎没有发现在病毒感染哺乳动物细胞过程中诱发有效的抗病毒RNAi反应。因此,人们希望能够利用人工方法在哺乳动物细胞中建立有效的抗病毒RNAi防御策略。迄今为止,对多种哺乳动物病毒的研究结果令人振奋。主要围绕RNAi的分子基础、基本策略及其在抑制口蹄疫病毒复制中的研究现状作了综述。  相似文献   
996.
贵州普定白岩脚洞石片的初步研究   总被引:1,自引:3,他引:1  
蔡回阳 《人类学学报》1989,8(4):335-342
本文对贵州普定白岩脚洞遗址中所获的1220件石片进行了分类观察。根据石片背面石皮的保存情况,疤与疤之间的关系,背疤的受力部位与石片台面的关系等特征,可从一个侧面反映出石核的利用率较高。  相似文献   
997.
998.
No single hypothesis or theory has been widely accepted for explaining the functional mechanism of global alpine/arctic treeline formation. The present study tested whether the alpine treeline is determined by (1) the needle nitrogen content associated with photosynthesis (carbon gain); (2) a sufficient source-sink ratio of carbon; or (3) a sufficient C-N ratio. Nitrogen does not limit the growth and development of trees studied at the Himalayan treelines. Levels of non-structural carbohydrates (NSC) in trees were species-specific and site-dependent; therefore, the treeline cases studied did not show consistent evidence of source/carbon limitation or sink/growth limitation in treeline trees. However, results of the combined three treelines showed that the treeline trees may suffer from a winter carbon shortage. The source capacity and the sink capacity of a tree influence its tissue NSC concentrations and the carbon balance; therefore, we suggest that the persistence and development of treeline trees in a harsh alpine environment may require a minimum level of the total NSC concentration, a sufficiently high sugar:starch ratio, and a balanced carbon source-sink relationship.  相似文献   
999.
1000.
报道了产自中国云南喀斯特地区的蜘蛛抱蛋属一新记录种——博格纳蜘蛛抱蛋(Aspidistra bogneri H.-J.Tillich)。该种以前报道仅产于越南宁平省菊芳国家公园(Ninh Binh,Cuc Phuong National Park),本次是中国首次记录。对该种的特征进行了详细描述并提供了彩色图片,凭证标本存放于中国科学院昆明植物研究所标本馆(KUN)。  相似文献   
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