松油烯-４-醇对粘虫幼虫的生物活性

测定了杀虫植物砂地柏Sabina vulgaris Ant.的精油中主杀虫成分-松油烯-4-醇（terpinen 4.01）对粘虫Mythimna separata Walker幼虫的生物活性。结果表明,松油烯- 4-醇对粘虫主要表现为熏蒸作用,对粘虫3龄幼虫24 h的熏蒸LC₅₀为5.3473 μL/L ;还具一定触杀作用,对粘虫4龄幼虫24 h的LD₅₀为147.8 μg/虫。试虫的中毒症状可明显地分为兴奋、痉挛、麻痹和死亡4个阶段,而麻痹的部分试虫有复苏现象。可明显抑制Na⁺ ,K⁺ATP酶的活性,在兴奋期、痉挛期、麻痹期和复苏期,抑制率介于21.28%～34.92% 之间。离体条件下对Na⁺,K⁺ATP酶的I₅₀为133.75 μg·mL^-1;对AChE活性有一定的影响;对酯酶,在兴奋期,酶活力为对照的7.0%,在麻痹期则为对照的1.33倍,而复苏期试虫的酯酶活力与对照相当。     

The crystal structure of a high affinity RNA stem-loop complexed with the bacteriophage MS2 capsid: further challenges in the modeling of ligand-RNA interactions

We have determined the structure to 2.8 A of an RNA aptamer (F5), containing 2'-deoxy-2-aminopurine (2AP) at the -10 position, complexed with MS2 coat protein by soaking the RNA into precrystallised MS2 capsids. The -10 position of the RNA is an important determinant of binding affinity for coat protein. Adenine at this position in other RNA stem-loops makes three hydrogen bonds to protein functional groups. Substituting 2AP for the -10 adenine in the F5 aptamer yields an RNA with the highest yet reported affinity for coat protein. The refined X-ray structure shows that the 2AP base makes an additional hydrogen bond to the protein compared to adenine that is presumably the principal origin of the increased affinity. There are also slight changes in phosphate backbone positions compared to unmodified F5 that probably also contribute to affinity. Such phosphate movements are common in structures of RNAs bound to the MS2 T = 3 protein shell and highlight problems for de novo design of RNA binding ligands.     

PML regulates p53 stability by sequestering Mdm2 to the nucleolus

The promyelocytic leukaemia (PML) tumour-suppressor protein potentiates p53 function by regulating post-translational modifications, such as CBP-dependent acetylation and Chk2-dependent phosphorylation, in the PML-Nuclear Body (NB). PML was recently shown to interact with the p53 ubiquitin-ligase Mdm2 (refs 4-6); however, the mechanism by which PML regulates Mdm2 remains unclear. Here, we show that PML enhances p53 stability by sequestering Mdm2 to the nucleolus. We found that after DNA damage, PML and Mdm2 accumulate in the nucleolus in an Arf-independent manner. In addition, we found that the nucleolar localization of PML is dependent on ATR activation and phosphorylation of PML by ATR. Notably, in Pml(-/-) cells, sequestration of Mdm2 to the nucleolus was impaired, as well as p53 stabilization and the induction of apoptosis. Furthermore, we demonstrate that PML physically associates with the nucleolar protein L11, and that L11 knockdown impairs the ability of PML to localize to nucleoli after DNA damage. These findings demonstrate an unexpected role of PML in the nucleolar network for tumour suppression.     

不同化学杂交剂(CHA)对小麦花药同工酶影响的研究

在小麦叶枕距±2cm时,喷施4种不同化学杂交剂（CHA）后,分别取小孢子处于不同发育阶段的花药,进行过氧化酶（POD）、淀粉酶（Amy）和酯酶（Est）等同工酶的分析。研究表明：在小孢子母细胞减数分裂期,处理2、3和4三种CHA对POD的A1、A2;B2、B4和B5,C1、C2和C3同工酶带的活性均有明显的抑制作用;处理5除去对A1和A2表现抑制外,对其他酶带的活性均有增强作用。在单枚早期,处理2和3的A、B和C区POD同工酶活性均明显低于对照;处理4和5上述各区POD同工酶活性却明显高于对照。在上述两个发育时期,处理2对Amy1区酶活性有增强作用,而处理3、4和5对该区酶活性却表现了专一性的抑制。各处理对Est同工酶A区和B区的酶活性主要表现为抑制。实验结果表明,不同的CHA均通过干扰花药的物质和能量代谢而导致雄性生理性不育。     

Cerebral metabolic response to submaximal exercise.

We studied cerebral oxygenation and metabolism during submaximal cycling in 12 subjects. At two work rates, middle cerebral artery blood velocity increased from 62 +/- 3 to 63 +/- 3 and 70 +/- 5 cm/s as did cerebral oxygenation determined by near-infrared spectroscopy. Oxyhemoglobin increased by 10 +/- 3 and 25 +/- 3 micromol/l (P < 0. 01), and there was no significant change in brain norepinephrine spillover. The arterial-to-internal-jugular-venous (a-v) difference for O(2) decreased at low-intensity exercise (from 3.1 +/- 0.1 to 2. 9 +/- 0.1 mmol/l; P < 0.05) and recovered at moderate exercise (to 3. 3 +/- 0.1 mmol/l). The profile for glucose was similar: its a-v difference tended to decrease at low-intensity exercise (from 0.55 +/- 0.05 to 0.50 +/- 0.02 mmol/l) and increased during moderate exercise (to 0.64 +/- 0.04 mmol/l; P < 0.05). Thus the molar ratio (a-v difference, O(2) to glucose) did not change significantly. However, when the a-v difference for lactate (0.02 +/- 0.03 to 0.18 +/- 0.04 mmol/l) was taken into account, the O(2)-to-carbohydrate ratio decreased (from 6.1 +/- 0.4 to 4.7 +/- 0.3; P < 0.05). The enhanced cerebral oxygenation suggests that, during exercise, cerebral blood flow increases in excess of the O(2) demand. Yet it seems that during exercise not all carbohydrate taken up by the brain is oxidized, as brain lactate metabolism appears to lower the balance of O(2)-to-carbohydrate uptake.     

基于多目标灰色局势决策的三峡库区防护林类型空间优化配置

基于2007年Landsat TM遥感影像和影响防护林的主导环境因子,对三峡库区的森林立地进行分类,并通过选取水源涵养量、生物量和林分生产力3个指标,利用多目标灰色局势决策模型对库区现有的针叶林、阔叶林、针阔混交林和灌木林4种防护林类型进行空间优化配置.结果表明： 2007年,三峡库区森林立地可划分为40种类型;空间配置优化后,研究区针叶林、阔叶林、针阔混交林和灌木林的面积比例分别为32.55%、29.43%、34.95%和3.07%.与优化前相比,优化后针叶林和灌木林的面积比例分别减少了8.79%和28.55%,阔叶林和针阔混交林分别增加了10.23%和27.11%.通过防护林类型的空间优化,三峡库区整体的水源涵养能力、生物量和林分生产力分别增加14.09×10⁸ m³、0.35×10⁸ t和1.08×10⁶ t.     

濒危平胸龟两个自然居群的ISSR分析

利用22个ISSR引物研究了28个来自广东从化居群和21个来自福建寿宁居群的野生平胸龟(Platysternon megacephalum)的遗传多样性。结果表明,分布于这两个地区的平胸龟总居群和居群内均具有较高的遗传多样性,而广东从化居群遗传多样性高于福建寿宁居群。居群间的遗传变异度FST=0.3715(P<0.001),遗传分化系数Gst为0.2059。NJ树聚类分析显示,广东从化居群和福建寿宁居群各自聚成两个类群,有较明显的居群分化,具有一定的地理区域性,但基因流Nm为1.9279,这表明平胸龟两自然居群间存在一定基因流。此外,结合BSA技术,从11条引物中筛选出11个可作为鉴别广东从化居群或福建寿宁居群的分子标记。     

粳稻SRAP分子标记遗传群的构建与分析

用超级稻品种‘沈农606’和普通粳稻‘丽江新团黑谷’为亲本杂交获得的102份F_2代单株,通过SRAP分子标记遗传分析,构建了包含14个连锁群,由129个多态性位点组成的水稻连锁图谱,此图谱覆盖基因组长度1671.5 cM,平均图距13.0 cM。连锁群上有17.2%的多态性位点表现偏分离,偏分离标记在连锁群上存在热点区域。     

人NFBD1启动子的鉴定与初步分析

NFBD1,也称MDC1,是一个参与细胞内DNA损伤后细胞应答反应的重要分子.为了进一步深入研究其转录调控机制,本研究克隆鉴定了NFBD1的启动子.首先应用5′ RACE技术鉴定了NFBD1的转录起始位点,首次发现NFBD1至少存在3种丰度和转录起始位点不同的转录变异体.然后,通过PCR定向克隆和酶切亚克隆策略,构建了覆盖NFBD1基因5′侧翼区起始密码子ATG上游5 kb区域的一系列NFBD1启动子荧光素酶报告基因重组体.启动子活性分析表明,NFBD1启动子区域定位于主要转录起始位点区域附近1.5 kb的区域内.采用转录因子结合位点预测分析软件分析表明,NFBD1启动子缺乏TATA盒,但含有典型的CCAAT盒和GC盒以及其它潜在的转录因子结合位点,提示Sp1和NF-Y等转录因子可能参与NFBD1的转录调控     

生物耐铜的分子机理及铜污染环境的生物联合修复

铜是动植物和人类必需的微量元素,缺乏或过多都将产生不良影响。随着社会经济的发展,人类活动对环境的干扰日益加剧,工业和农业生产活动常可导致土壤铜污染,铜已成为土壤重金属污染的主要元素之一。总结了铜在植物体内的自发内稳态调节机制,在细菌和真菌体内的吸收、分布、解毒和调节因子,同时以蚯蚓为例简要阐述了土壤动物对铜的解毒机理;从分子生物学角度对重金属铜在生物体内的代谢机理及生物对环境中过量铜的联合修复研究进展进行了综述,以期为铜污染环境的植物、微生物和动物联合修复的分子机理研究提供借鉴。