越南槐根的抗HIV活性成分研究

为研究越南槐(Sophora tonkinensis)根的抗HIV蛋白酶活性成分及其分子对接机制,采用硅胶、MCI、Sephadex LH-20等多种色谱分离方法,对越南槐根的化学成分进行分离,采用HIV蛋白酶对化合物进行体外抗HIV活性筛选,运用分子对接手段初步探究活性化合物与HIV-1蛋白酶的结合机制。结果表明,从越南槐中共分离得到8个化合物,根据波谱数据分别鉴定为三叶豆紫檀苷(1)、苦参碱(2)、N-acetylnicotinamide (3)、2′-O-甲基腺苷(4)、毛蕊异黄酮苷(5)、玫瑰花苷(6)、环广豆根素(7)、芒柄花苷(8),此外还分离得到塑化剂衍生物邻苯二甲酸二(2-乙基)己酯(9)和邻苯二甲酸二异丁酯(10)。抗HIV蛋白酶活性测试显示化合物1和2的IC50分别为13.2和38.6μg/m L,分子对接表明其与HIV蛋白酶有一定的结合作用。化合物3～5为首次从该植物中分离得到,化合物1和2显示中等的抗HIV蛋白酶活性。     

鼠兔核质杂交胚胎早期发育的研究

细胞核移植技术已被证明是研究发育中核质相互关系的非常重要的手段之一,电融合技术也是近十年发展起来的新型细胞融合技术。本实验运用这两项技术,进行了鼠、兔目间核质杂交实验,小鼠8-细胞核在激活的兔去核卵母细胞中,发生了染色体超前凝聚及核膨胀,融合卵移植到小鼠输卵管4.5天后,冲洗出,有5.4%的重构卵发育到囊胚期,通过染色体检查,囊胚细胞中均为小鼠染色体,其中一个囊胚为正常小鼠核型(2 n=40,XX)。通过本实验,我们认为:鼠兔远缘核质杂交胚胎的早期发育是可能的。     

ARK2 stabilizes the plus-end of microtubules and promotes microtubule bundling in Arabidopsis

Microtubule dynamics and organization are important for plant cell morphogenesis and development. The microtubule-based motor protein kinesins are mainly responsible for the transport of some organelles and vesicles, although several have also been shown to regulate microtubule organization. The ARMADILLO REPEAT KINESIN (ARK) family is a plant-specific motor protein subfamily that consists of three members (ARK1, ARK2, and ARK3) in Arabidopsis thaliana. ARK2 has been shown to participate in root epidermal cell morphogenesis. However, whether and how ARK2 associates with microtubules needs further elucidation. Here, we demonstrated that ARK2 co-localizes with microtubules and facilitates microtubule bundling in vitro and in vivo. Pharmacological assays and microtubule dynamics analyses indicated that ARK2 stabilizes cortical microtubules. Live-cell imaging revealed that ARK2 moves along cortical microtubules in a processive mode and localizes both at the plus-end and the sidewall of microtubules. ARK2 therefore tracks and stabilizes the growing plus-ends of microtubules, which facilitates the formation of parallel microtubule bundles.     

Genome-wide identification,classification, and expression profiling of serine esterases and other esterase-related proteins in the tobacco hornworm,Manduca sexta

Serine esterases (SEs) are hydrolases that catalyze the conversion of carboxylic esters into acids and alcohols. Lipases and carboxylesterases constitute two major groups of SEs. Although over a hundred of insect genomes are known, systematic identification and classification of SEs are rarely performed, likely due to large size and complex composition of the gene family in each species. Considering their key roles in lipid metabolism and other physiological processes, we have categorized 144 M. sexta SEs and SE homologs (SEHs), 114 of which contain a motif of GXSXG. Multiple sequence alignment and phylogenetic tree analysis have revealed 39 neutral lipases (NLs), 3 neutral lipase homologs (NLHs), 11 acidic lipases (ALs), 3 acidic lipase homologs (ALHs), a lipase-3, a triglyceride lipase, a monoglyceride lipase, a hormone-sensitive lipase, and a GDSL lipase. Eighty-three carboxylesterase genes encode 29 α-esterases (AEs), 12 AEHs (e.g., SEH4-1–3), 20 feruloyl esterases (FEs), 2 FEHs, 2 β-esterases (BEs), 2 integument esterases (IEs), 1 IEH, 4 juvenile hormone esterases, 2 acetylcholinesterases, gliotactin, 6 neuroligins, neurotactin, and an uncharacteristic esterase homolog. In addition to these GXSXG proteins, we have identified 26 phospholipases and 13 thioesterases. Expression profiling of these genes in specific tissues and stages has provided insights into their functions including digestion, detoxification, hormone processing, neurotransmission, reproduction, and developmental regulation. In summary, we have established a framework of information on SEs and related proteins in M. sexta to stimulate their research in the model species and comparative investigations in agricultural pests or disease vectors.     

THE ROLE OF BACTERIAL SYMBIONTS IN AMINO ACID COMPOSITION OF BLACK BEAN APHIDS

To evaluate the role of bacterial symbionts (Buchnera spp.) in the black bean aphids (Aphis craccivora Koch), the aphids were treated with the antibiotic, rifampicin, to eliminate their intracellular symbiotic bacteria. Analysis of protein and amino acid concentration in 7‐day‐old of aposymbiotic aphids showed that the total protein content per mg fresh weight was significantly reduced by 29%, but free amino acid titers were increased by 17%. The ratio of the essential amino acids was in general only around 20% essential amino acids in phloem sap of broad bean, whereas it was 44% and 37% in symbiotic and aposymbiotic aphids, respectively, suggesting that the composition of the free amino acids was unbalanced. For example, the essential amino acid, threonine represented 21.6% of essential amino acids in symbiotic aphids, but it was only 16.7% in aposymbiotic aphids. Likewise, two nonessential amino acids, tyrosine and serine, represented 8.9% and 5.6% of total amino acids in symbiontic aphids, respectively, but they enhanced to 21.1% and 13.6% in aposymbiotic aphids. It seems likely that the elevated free amino acid concentration in aposymbiotic aphids was caused by the limited protein anabolism as the result of the unbalanced amino acid composition.     

板齿鼠种群数量中长期预测的时间序列模型

本文利用时间序列方法（三次指数平滑法）,并结合季节指数法,建立了板齿鼠种群数量中长期预测（６个月～１年）的时间序列模型,依据１９９１年１１月～１９９３年１２月在广东省博罗县石湾镇里波水管理区对板齿鼠种群数量动态的调查数据,分别预测了１９９４年和１９９５年板齿鼠种群数量的发生,预测准确率达到了８６．５６％。     

静电作用与修饰铜锌超氧化物歧化酶的稳定性

铜锌超氧化物歧化酶(Cu, Zn-SOD)表面的赖氨酸经化学修饰后, 酶的稳定性显著提高. 赖氨酸被修饰后, 酶的电荷结构遂发生变化, 从而影响到酶分子电场. 使用FDPB方法(有限差分法求解Poission-Boltzman方程)计算了酶修饰前后的静电场变化, 以及对维持酶的结构稳定起重要作用的Cu, Zn配位结构的影响.结果表明, Cu, Zn配位体的两级离解常数在酶修饰后分别约下降10³, 10⁶.     

白玉兰播种苗年生长规律的研究

本文通过对白玉兰一年生播种苗年生长进程的研究,阐明了苗高、地径的年变化规律,并拟合其生长模型,从而为生产上有效采取育苗措施提供科学依据．     

水稻幼穗组培及白化苗的电镜观察

木文报道了五份水稻材料的幼穗组培的诱导率和分化率,对继代８次后的幼穗愈伤分化出的白苗和绿苗及其各自的愈伤进行电镜扫描,发现白苗的质体结构不完整,不能正常合成叶绿素。     

The interaction of RepC initiator with iterons in the replication of the broad host-range plasmid RSF1010.

The replication origin of the broad host-range plasmid RSF1010 contains 3.5 copies of a 20mer iteron sequence that bind specifically to the plasmid-encoded initiator, RepC. Here we demonstrated that even a single iteron was bent upon binding of RepC. Moreover, the bending angle seems to become larger along with the increment of the number of iterons. In a mutational analysis of the iteron sequence, we isolated seven kinds of base-substitution mutants of iterons, and estimated the replication activity of these mutants in vivo. We found that each of the subsections in the 20mer iteron sequence made a distinct contribution to the initiation of RSF1010 DNA replication. With the binding assay of RepC and mutated iterons in vitro, we found that the formation of a productive RepC-iteron complex was required for the initiation of plasmid DNA replication.