硼对植物生殖器官建成的作用

实验以黄瓜植物为材料，研究了硼在个体水平上和器官水平上对植物生殖器官建成的作用，并用放射性同位素示踪法研究了硼对植物生殖器官的作用同植物体内糖运输的关系。结果表明，在个体水平上，缺硼使植物体上雄花和雌花数目都减少，但缺硼对雌花形成和雄花形成的影响并不相同，缺硼使植物体上形成较多的雄花，较少的雌花。在器官水平上，硼的作用同它的浓度有关，在某一浓度范围内，缺硼不利于黄瓜花蕾发育成雌花-也不利于雄花花药的发育;硼浓度的升高有利于花蕾发育成雌花，也有利于发育成雄花的花蕾花药的发育。较高浓度的硼则明显使黄瓜花蕾不易发育成雌花，但有利于发育成雄花的花蕾花药的发育。在个体水平上，缺硼对生殖器官建成的作用同花蕾组织中可溶性糖的缺乏有关，这可能是由于缺硼抑制了茎等输导组织的糖吸收活动而使叶片光合作用所合成的糖不易运到花蕾中的原因。

A new protein structure of P-II class snake venom metalloproteinases: it comprises metalloproteinase and disintegrin domains

A new metalloproteinase-disintegrin, named Jerdonitin, was purified from Trimeresurus jerdonii venom with a molecular weight of 36 kDa on SDS-PAGE. It dose-dependently inhibited ADP-induced human platelet aggregation with IC50 of 120 nM. cDNA cloning and sequencing revealed that Jerdonitin belonged to the class II of snake venom metalloproteinases (SVMPs) (P-II class). Different from other P-II class SVMPs, metalloproteinase and disintegrin domains of its natural protein were not separated, confirmed by internal peptide sequencing. Compared to other P-II class SVMPs, Jerdonitin has two additional cysteines (Cys219 and Cys238) located in the spacer domain and disintegrin domain, respectively. They probably form a disulfide bond and therefore the metalloproteinase and disintegrin domains cannot be separated by posttranslationally processing. In summary, comparison of the amino acid sequences of Jerdonitin with those of other P-II class SVMPs by sequence alignment and phylogenetic analysis, in conjunction with natural protein structure data, suggested that it was a new type of P-II class SVMPs. (C) 2003 Elsevier Inc. All rights reserved.

Polymorphism in mitochondrial DNA (mtDNA) of yak (Bos grunniens)

Mitochondrial DNAs (mtDNA) from 21 yaks (Bos grunniens) were assayed for restriction fragment length polymorphisms by using 20 restriction endonucleases, six of which (AvaI, AvaII, BglII, EcoRI, HindIII, and HpaI) detected polymorphism. Four different mtD

Recent advance in the study of intein

Since the first intein was found, more and more attention were paid on it. It not only enrichs the content of the process that the gene transfers its information but also can be used in protein purification. The recent advance in the sequence characterist

A STUDY ON THE EFFECT OF LESIONS OF AREA-7 OF THE PARIETAL CORTEX ON THE SHORT-TERM VISUAL SPATIAL MEMORY OF RHESUS-MONKEYS (MACACA-MULATTA)

This research is focused on the contribution of area 7 to the short-term visual spatial memory. Three rhesus monkeys (Macaca mulatta) were trained in the direct delayed response task in which 5 delay intervals were used in each session. When each monkey reached the criterion of 90% correct responses in 5 successive sessions, two monkeys underwent a surgery while the other one received a sham operation as a control. In the first stage of the surgery, bilateral areas 7a, 7b and 7ip of the parietal cortex of two monkeys were precisely lesioned. After 7 days of recuperation, the monkeys were required to do the same task. The average percentage of correct responses in the lesioned animals decreased from 94.7% to 89.3% and 93.3% to 82.0% respectively (no significance, P > 0.05, n = 2). In addition, the monkeys' complex movements were mildly impaired. The lesioned monkeys were found to have difficulty picking up food from the wells. In the second stage, bilateral area 7m was lesioned. In the 5 postoperative sessions, the average percentage of correct responses in one monkey, with a relatively precise 7m lesion, decreased from 94.7% to 92.2% (no significance, P > 0.05), while the other monkey, with widely spread necrosis of lateral parietal cortex, showed an. obvious decline in performance, but still over the chance level. After 240 trials this monkey reattained the normal criterion. The results of this research suggest that the lesions of area 7 of the parietal cortex did not significantly affect the short-term visual spatial memory, which has been shown to be sensitive to lesions of the prefrontal cortex; they also support the notion of dissociation of spatial functions in the prefrontal and parietal cortices.

咪唑安定或丙泊酚拮抗戊四氮对突触传递的影响

目的: 观察咪唑安定或丙泊酚复合戊四氮对突触传递的影响。方法: 分离大鼠海马半脑, 切出400 Lm 厚度的海马脑片, 全细胞膜片钳记录戊四氮+ 咪唑安定组, 戊四氮+ 脂肪乳剂组, 戊四氮+ 丙泊酚组海马CA 1 区神经元兴奋性突触后电流(EP2 SC) 变化。结果: 各组加入10 mmolöL 戊四氮均使EPSC 降至基线值的3510% 左右; 10 LmolöL 咪唑安定使EPSC 幅值上升至 基线值的8612% , 脂肪乳剂不改变EPSC, 100 LmolöL 丙泊酚使EPSC 值上升至基线值的7117%。结论: 戊四氮对正常突触传 递具有抑制作用, 咪唑安定或丙泊酚拮抗戊四氮抑制突触传递的作用, 使已减小的EPSC 有所升高。

The effect of acute stress on LTP and LTD induction in the hippocampal CA1 region of anesthetized rats at three different ages

Not all experiences are memorized equally well. Especially, some types of stress are unavoidable in daily life and the stress experience can be memorized for life. Previous evidence has showed that synaptic plasticity, such as long-term potentiation (LTP) that may be the major cellular model of the mechanism underlying learning and memory, is influenced by behavioral stress. However, the effect of behavioral stress on age-related synaptic plasticity in-vivo was primarily known. Here we found that the LTP induction in the hippocampal CA1 region of anesthetized rats obviously showed inverted-U shape related to ages (4, 10 and 74 weeks old rats), but low-frequency stimulation was unable to induce reliable long-term depression (LTD) in these animals. Furthermore, acute elevated platform (EP) stress enabled reliable LTD significantly and completely blocked LTP induction at these ages. Importantly, LTD after exposure to acute EP stress showed similar magnitude over these ages. The present results that stress enables LTD but impairs LTP induction at these three ages strengthen a view that stress experience-dependent LTD (SLTD) may underlie stress form of aberrant memories. (C) 2004 Elsevier B.V. All rights reserved.

信息素受体V1R基因家族基因数目在哺乳动物中存在巨大差异

信息素是由动物分泌的化学物质,用于影响同种动物的行为,其感觉器官叫做犁鼻器,是一个位于鼻中隔底部的软骨结构。信息素受体由V1R和V2R两个基因超家族编码。美国密歇根大学张建之研究小组与中科院昆明动物所张亚平等合作,通过对目前可利用的哺乳动物基因组工作草图的分析,发现V1R基因家族的基因数目在哺乳动物中存在着巨大的差异,是目前所知的基因数目差异倍数最大的哺乳动物基因家族,其中,小鼠、老鼠、狗、牛和负鼠的V1R基因数目分别为187、102、8、32和49。研究人员认为,V1R基因家族这种惊人的差异主要是由基因的快速新生与消亡过程造成的,即:在食肉类和偶蹄类动物中多次发生丢失祖先V1R基因的情况,而在啮齿类动物中却通过基因重复的形式产生了许多新基因。V1R基因家族在不同物种中的巨大差异可能反映了不同物种对信息素的感受能力的不同。此外,该研究结果还表明了V1R基因家族的大小和犁鼻器形态上的复杂程度紧密相关,提示着具有形态复杂的犁鼻器的物种可能也具有复杂的信息素传递系统。该研究结果不仅证明了哺乳动物的V1R基因家族惊人的多样性和快速的进化历程,还提示当利用模式生物小鼠所获得的信息素知识推广、应用到其它的哺乳动物时,一定...