^60Co—γ射线诱导的小麦T型雄性不育系育性恢复突变

用~(60)Co-γ射线诱导小麦T型雄性不育系T小偃4号A、T郑引1号A均获得了农艺性状优良、恢复力强的恢复系。育性恢复突变是涉及一个或少数几个位点核基因的显性突变。利用性状优良的T型不育系诱导育性恢复突变是选育恢复系和发掘恢复源的有效途径。     

PUC衍生质粒的一个低拷贝数突变型

本文报道大肠杆菌的ColE1类似质粒的一个低拷贝数突变型。从载体质粒pUC4衍生的重组质粒pPGVT3在大肠杆菌宿主DF2145中是不稳定的,以pPGVT3转化DF2145时在4o℃培养得不到转化子。用诱发点突变的羟胺体外处理pPGVF3质粒DNA,得到一个稳定性提高了的突变质粒pPGVT3HA,突变的位置被确定在质粒的pUC部分,突变降低了pUC及其衍生质粒的拷贝数。文中对质粒的稳定性与拷贝数的关系作了讨论。     

第Ⅷ凝血因子基因内限制性片段长度多态性(RFLP)的研究及其在甲型血友病基因连锁分析中的应用

本文系统地研究了广东地区汉族人群中FⅧ:C基因内BclⅠ,XbaⅠ和BgⅡ位点RFLP的基因频率。多态性位点BclⅠ,XbaⅠ及BglⅠ的切点阳性率分别为63.5%、43.5%和100%。对Bcll和Xbal多态性切点连锁情况研究显示,19.5%的Bcll切点阳性纯合子为Xbal切点杂合子,证明联合应用此两位点RFLP可以把甲型血友病基因连锁分析的有效率提高到65.9%。用RFLP连锁分析对两例甲型血友病家系中的女性进行了致病基因携带者检测,对另一例家系进行了基因产前诊断。     

棉属栽培种与野生种杂交的不亲和性

本文研究了棉属栽培种与野生种杂交的不亲和性,试验材料涉及5个染色体组,包括2个栽培种(陆地棉和中棉)和5个野生种(戴维逊氏棉、瑟伯氏棉、三裂棉、阿拉伯棉和比克氏棉)。以陆地棉作母本,异己花粉管在花柱中生长缓慢,有花粉管胚珠低于10%,陆地棉×戴维逊氏棉杂种胚在子叶期坏死。以中棉作母本,不亲和性主要表现在受精后的胚胎发育过程中。     

Mechanics of running under simulated low gravity.

Using a linear mass-spring model of the body and leg (T. A. McMahon and G. C. Cheng. J. Biomech. 23: 65-78, 1990), we present experimental observations of human running under simulated low gravity and an analysis of these experiments. The purpose of the study was to investigate how the spring properties of the leg are adjusted to different levels of gravity. We hypothesized that leg spring stiffness would not change under simulated low-gravity conditions. To simulate low gravity, a nearly constant vertical force was applied to human subjects via a bicycle seat. The force was obtained by stretching long steel springs via a hand-operated winch. Subjects ran on a motorized treadmill that had been modified to include a force platform under the tread. Four subjects ran at one speed (3.0 m/s) under conditions of normal gravity and six simulated fractions of normal gravity from 0.2 to 0.7 G. For comparison, subjects also ran under normal gravity at five speeds from 2.0 to 6.0 m/s. Two basic principles emerged from all comparisons: both the stiffness of the leg, considered as a linear spring, and the vertical excursion of the center of mass during the flight phase did not change with forward speed or gravity. With these results as inputs, the mathematical model is able to account correctly for many of the changes in dynamic parameters that do take place, including the increasing vertical stiffness with speed at normal gravity and the decreasing peak force observed under conditions simulating low gravity.     

鄂西南香蒲科、黑三棱科、眼子菜科和茨藻科植物区系特征

本文在采集标本基础上,结合分析大量有关资料,讨论了鄂西南香蒲科等四科植物区系特征。结果表明:1.区系组成包括5属20种2变种1杂种。其中有1新种1新变种和3个湖北分布新记录。2.区系种类丰富,起源古老,对湖北同类区系具有代表性。3.有一定比例的特有成分(8.70%)。4.区系地理成分复杂多样,但主要具有东亚亚热带一温带分布(26.09%)和世界性分布(26.09%)的性质。5.本区四科植物区系主要与处于我国地貌第三级阶梯上的省区发生密切联系。其区系分区,在亚区的划分上与陆生种子植物相同。     

水库鲢鳙鱼生长状况的评价预测

一.引言一般生物受许多环境因素的约束和作用。我们根据有关生物学理论、专家意见和调查材料,结合河北省抚宁县洋河水库现状材料和拟议中筹建的河北省青龙县桃林口水库建库后水质、生态环境的预测,应用层次分析法和综合评定法,对上述两水库的鲢、鳊鱼生长状况.进行评价和预测。     

从我国成人手足口病患者疱液中首次分离出肠道病毒71型

本文报道了从我国手足口病(HFMD)患者疱液中肠道病毒71(E71)型H株的分离和鉴定。该株病毒可在原代人胚肺(HEL)细胞、MA104细胞、BSC细胞中生长繁殖,导致典型的肠道病毒CPE出现。将H株接种乳鼠后出现肢体麻痹、第6天开始死亡。电镜下可见感染H株的BSC细胞胞浆中出现大量的结晶状排列的成熟病毒颗粒,直径约25nm。患者双份血清中有对H株4倍增高的中和抗体存在。采用100抗体单位的抗Cox A5、7、9、16、E70、E71抗体和50抗体单位的LBM组合血清A-H以及抗E71BrCr株MeAb P27对H株进行中和试验时,H株可被抗E71血清和MeAb P27所中和。抗E71抗体对H株的最低有效中和作用为1.6抗体单位,MeAb P27对H株的有效中和作用是64抗体单位。其它血清则无此中和作用。然而,在鉴定过程中发现,高滴度的抗Cox A16抗体(200抗体单位以上)也显出有中和H株的作用,提示我们所分离的H株含有与Cox A16的型间共同抗原。     

Evidence for two modes of Ca2+ entry following muscarinic stimulation of a human salivary epithelial cell line

Summary We have investigated muscarinic receptor-operated Ca²⁺ mobilization in a salivary epithelial cell line, HSG-PA, using an experimental approach which allows independent evaluation of intracellular Ca²⁺ release and extracellular Ca²⁺ entry. The carbachol (Cch) dose response of intracellular Ca²⁺ release indicates the involvement of a single, relatively low-affinity, muscarinic receptor site (K _0.510 or 30 m, depending on the method for [Ca²⁺] _i determination). However, similar data for Ca²⁺ entry indicate the involvement of two Cch sites, one consistent with that associated with Ca²⁺ release and a second higher affinity site withK _0.52.5 m. In addition, the Ca²⁺ entry response observed at lower concentrations of Cch (2.5 m) was completely inhibited by membrane depolarization induced with high K⁺ (>55mm) or gramicidin D (1 m), while membrane depolarization had little or no effect on Ca²⁺ entry induced by 100 m Cch. Another muscarinic agonist, oxotremorine-M (100 m; Oxo-M), like Cch, also induced an increase in the [Ca²⁺] _i of HSG-PA cells (from 72±2 to 104±5nm). This response was profoundly blocked (75%) by the inorganic Ca²⁺ channel blocker La³⁺ (25–50 m) suggesting that Oxo-M primarily mobilizes Ca²⁺ in these cells by increasing Ca²⁺ entry. Organic Ca²⁺ channel blockers (verapamil or diltiazem at 10 m, nifedipine at 1 m), had no effect on this response. The Oxo-M induced Ca²⁺ mobilization response, like that observed at lower doses of Cch, was markedly inhibited (70–90%) by membrane depolarization (high K⁺ or gramicidin D). At 100 m Cch the formation of inositol trisphosphate (IP₃) was increased 55% above basal levels. A low concentration of carbachol (1 m) elicited a smaller change in IP₃ formation (25%), similar to that seen with 100 m Oxo-M (20%). Taken together, these results suggest that there are two modes of muscarinic receptor-induced Ca²⁺ entry in HSG-PA cells. One is associated with IP₃ formation and intracellular Ca²⁺ release and is independent of membrane potential; the other is less dependent on IP₃ formation and intracellular Ca²⁺ release and is modulated by membrane potential. This latter pathway may exhibit voltage-dependent gating.     

Bezold—Jarisch反射的生理机制与病理生理意义

Bezold-Jarisch反射是源于心脏内感受器的抑制性反射,其感受器主要分布在左心室,化学性和机械性刺激均可使之兴奋。感觉冲动经迷走神经无髓纤维上传,反射地引起交感传出活动减弱和迷走传出活动增强,终致心动徐缓和低血压。急性心肌梗塞、冠脉造影和劳力性晕厥时,有Bezold-Jarisch反射参与;慢性心衰和高血压时,心脏内感受器发生重调,反射的敏感性降低。