Double-gating mechanism and diversity of an adenosine triphosphate (ATP)-sensitive K~ channel in neurons acutely dissociated from rat neocortex

Classically, ion channels are classified into 2 groups: chemical-sensitive (ligand-gated) and voltage-sensitive channels. Single ATP-sensitive K (K-ATP) channel currents were recorded in acutely dissociated rat neo-cortical neurons using patch clamp technique. A type of K-ATP channel has been found to be gated not only by intra-cellular ATP, but also by membrane potential ( Vm) , and proved to be a novel mechanism underlying the gating of ion channels, namely bi-gating mechanism. The results also show that the K-ATP channels possess heterogeneity and di-versity. These types of K-ATP channels have been identified in 40.12% of all patches, which are different in activa-tion-threshold and voltage-sensitivity. The present experiment studied the type-3 K-ATP channel with a unitary con-ductance of about 80 pS in detail ( n = 15). Taking account of all the available data, a variety of K-ATP channels are suggested to exist in body, and one type of them is bi-gated by both chemical substances and membrane poten     

Sequence analysis of lacZ- mutations induced by ion beam irradiation in double-stranded M13mp18DNA

While M13mp18 double-stranded DNA was irradiated with ion beam, and transfected intoE. coli JM103, a decrease of transfecting activity was discovered. The lacZ^- mutation frequency at 20% survival could reach (3.6–16.8) × 10⁴, about 2, 3–10 times that of unirradiated M13DNA. Altogether, 27 IacZ^-mutants were selected, 10 of which were used for sequencing. 7 of the sequenced mutants show base changes in 250-bp region examined (the remaining 3 mutants probably have base changes outside the regions sequenced). 5 of the base-changed mutants contain more than one mutational base sites (some of them even have 5–6 mutational base sites in 250-bp region examined); this dense distribution of base changes in polysites has seldom been seen in X-rays, Y-rays or UV induced DNA mutations. Our experiments also showed that the types of base changes include transitions(50%), transversions (45%) and deletion (5%); no addition or duplication was observed. The transitions were mainly C→T and A→G; the transversions were mainly C→A and C→G. The mutations involving cytosine residue (in the template strand) constitute about 60% of all the base changes observed. In comparison with the surrounding sequences of mutational base sites, the base located between TG and CT is found to be easily substituted.     

Sequence variation and genetic diversity in the giant panda

About 336–444 bp mitochondrial D-loop region and tRNA gene were sequenced for 40 individuals of the giant panda which were collected from Mabian, Meigu, Yuexi, Baoxing, Pingwu, Qingchuan, Nanping and Baishuijiang, respectively. 9 haplotypes were found in 21 founders. The results showed that the giant panda has low genetic variations, and that there is no notable genetic isolation among geographical populations. The ancestor of the living giant panda population perhaps appeared in the late Pleistocene, and unfortunately, might have suffered bottleneck attacks. Afterwards, its genetic diversity seemed to recover to some extent. Project supported by the “8.5” Key Project of Chinese Academy of Sciences, the Chairman Foundation of Chinese Academy of Sciences, K. C. Wang Education Foundation, the Applied Basic Research Foundation of Yunnan, the National Natural Science Foundation of China, the Special Foundation for Returned Chinese Scientists, and Zoological Society of San Diego.     

两种吸血水蛭对光闪烁和水扰动刺激的反应

利用自制的控温实验槽在暗室内进行医蛭科两种吸血水蛭对光闪烁和水扰动刺激的模拟个体生态实验,实验结果的统计分析表明,日本医蛭在１６℃时与照度有极好的正相关关系,而在２２℃时成负相关关系,０．２克体重的个体在两种温度对照度的敏感度均大于０．５－０．６克和１．０－１．３克体重的个体,湖北牛蛭在两种温度时与照度均成正相关关系;０．５克体重的个体在１６℃时对照度的敏感度大于１．０－３．３克体重的个体９．５－     

日本血吸虫尾蚴发育的超微结构观察：Ⅱ.腺体

在透射电镜下观察不同发育期日本血吸虫尾蚴的腺体。结果：胚球期（Ｓ２）主要出现体细胞分裂与分化,首次证明分泌细胞及其小体在Ｓ２出现,雏体期（Ｓ３）见到前钻腺细胞体与钻腺管束及分泌小体。成熟前期（Ｓ４）钻腺分泌小体基质分Ａ／Ｂ为主两型,分别演变为成熟期（Ｓ）５的后／前钻腺分泌小体。头腺分泌小体亦在Ｓ４出现。从前钻腺体排至头器远端腺管的分泌小体,显眼透明球消失成为致密同质性小体,已为大家共识。而在后钻腺     

新型γ－氨基丁酸受体：GABAc受体

众多的证据表明,在神经系统,特别是视觉神经通路中,除通常的ＧＡＢＡＡ和ＧＡＢＡＢ受体之外,还存在着一种具有不同药理特性的ＧＡＢＡＣ受体。这种受体不为荷包牡丹碱（ｂｉｃｕｃｕｌｌｉｎｅ）所阻遏,亦不为氯苯氨丁酸（ｂａｃｌｏｆｅｎ）所激活,在激活后并不显示失敏现象,可能在视网膜中视杆通路的信,自传递和调控中起重要作用。     

东北羊草草原土壤微生物生物量的季节变化及其与土壤生境的关系

本文研究东北羊草草原土壤微生物生物量的季节变化规律。根据实测数据,利用ＭＶ／６０００电子计算机构造了趋势方程,并作了Ｆ检验,Ｆ０．２５＝２．６８,Ｆ０＝１９３．９９,效果良好。以此为基础可以进行预测预报。同时利用ＭＶ／６０００电子计算机绘制三维空间趋势面图形,直观地反映了东北草草原土壤分解微生物生物量的季节变化规律。实验结果证明,土壤温度、水分对土壤微生物的生物量影响同等重要。     

洪湖生态环境的化学结构

本文探讨了化学元素在洪湖水、植物、沉积物中的分布,在此基础上分析了水生植物对元素的吸收特征及元素在生态系统中的贮存和迁移规律。指出湖水中Ｃａ￣（２＋）和是主要的阳离子和阴离子,湖水酸容纳能力在１．２×１０￣（－３）－２．０×１０￣（－３）ｍｏｌ／ｌＨ￣＋之间,水化学的稳定性受到碳酸盐地球化学平衡过程的控制;湖中水生植物具有富集Ｃ、Ｎ、Ｋ、Ｃａ和Ｃｄ的性质,并导致这些元素在沉积物表层集累;系统中Ｃ多存在于植物体中,Ｎ、Ｐ、Ｋ、Ｃａ和Ｍｇ多存在于沉积物中,沉积物分室是营养元素主要的贮存库。     

东北羊草草原综合生态因子对微生物生长的作用──IRM模型的研究

本文从分解者亚系统水平研究了东北羊草草原土壤中微生物生长的季节变化．多种生态因子的季节变化及环境因子对微生物的综合作用规律。微生物总数,总生物量和总呼吸强度的季节动态呈单峰上凸式曲线变化,８月份有明显的高峰值出现,它们分别为：２６８９．０×１０￣４个／ｇ·干土、２５．４１×１０￣（０３）ｇ／ｇ·干土、０．８９５２×１０￣（－３）ｇＣＯ＿２／ｇ·干土·ｄ。土壤生态因子的季节变化与土壤微生物呈现不同程度的正相关和负相关。同时利用ＩＲＭ的模型─—探讨了生态因子对微生物生长的综合作用规律：生态因子对微生物生长的综合作用指数ｒ＿ｎ在整个生长季节中为０．００３１８－０．１１１５,其中７－９月份ｒ＿ｎ较大,对出生物生长的限制作用较小,微生物生长较快,５、６和１０月份ｒ＿ｎ较小,对微生物生长限制作用较大,微生物生长较慢。     

金鱼草胚囊的人工分离

用果胶酶与纤维素酶的混合液离解金鱼草的胚珠,从中分离出完整的胚囊。由固定材料分离的胚囊,经透明染色后可借助干涉差显微装置观察由受精前直至受精后具上百个胚乳细胞时期的胚囊的内部结构。由新鲜胚珠分离胚囊也已初步突破,并对其作了简易的显微化学观察。讨论了活胚囊分离的意义与胚囊离体培养的前景。