越冬期间香蕉果穗套袋的防寒效果及其对产量的影响

冬季香蕉果穗用兰色聚乙烯薄膜套袋之后,可提高袋内温度1～5℃,果实低温伤害卑只有1％左右,而未经套袋的达23％～35％,果指长度和径围增加率分别达12％和9％左右,果实产量比对照增加8％～16％。试验结果表明,兰色聚乙烯薄膜套袋是越冬期间香蕉防寒保果和增产的一项有效措施。     

PVA和PEG(6000)预处理对大豆胚轴生长、蛋白质合成和ATP含量的影响

在低温吸胀阶段,经PVA(聚乙烯醇)和PEG(聚乙二醇6000)预处理的大豆胚轴蛋白质合成和ATP含量均比对照高。在萌发阶段,胚轴生长增快,蛋白质合成明显加快,ATP迅速被消耗,而对照胚轴则相反。试验结果表明,预处理大豆种子萌发和生长与其蛋白质合成、ATP水平和消耗能力有密切关系。     

外来入侵植物的根系觅养行为研究进展

土壤养分分布具有高度空间异质性, 植物的根系觅养行为是其对土壤养分异质性的一种适应。不同植物为了适应养分异质性会产生不同的根系觅养行为, 通过调整自身的根系觅养范围、觅养精度和觅养速度来更好地吸收利用土壤中的养分。外来植物与本地植物的竞争是决定其成功入侵的重要因素, 土壤养分等环境因素会影响它们之间的竞争关系。近年来, 外来入侵植物的觅养行为逐渐受到人们的关注, 关于入侵植物根系觅养行为的研究成果陆续出现: (1)总体来看, 外来入侵植物具有较强的根系觅养能力, 但根系觅养范围与觅养精度之间的权衡关系还不确定; (2)营养异质性会影响入侵植物与本地植物之间的竞争, 反过来, 二者之间的竞争也会影响根系觅养行为对营养异质性的响应; (3)丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)能够提高入侵植物的根系觅养能力, 外来植物入侵能够改变入侵植物对AMF的偏好性, 形成AMF对入侵的正反馈作用, 而本地植物与AMF的相互作用也会影响入侵植物的竞争力。未来还应加强营养异质环境下种间竞争和AMF共生对入侵植物根系觅养行为的影响机制研究, 以及全球变化背景下入侵植物根系觅养行为的变化与机制方面的研究, 可以更深入地认识外来植物的觅养行为在其成功入侵中的作用, 并为利用营养调控来防控入侵植物提供理论依据。     

橡胶树橡胶生物合成调控相关基因的表达相关性分析

该文通过qPCR获得了正常割胶条件下,9个茉莉酸信号途径关键环节基因HbCOI1、HbJAZ1、HbJAZ2、HbJAZ3、HbMYC1、HbMYC2、HbMYC3、HbMYC4、HbMYC5和6个橡胶生物合成相关基因HbHRT2、HbSRPP、HbREF、HbHMGR1、HbHRT1、HbGAPDH在5个橡胶树魏克汉种质和5个1981''IRRDB种质胶乳中的表达数据; 通过皮尔逊相关系数分析了这15个基因彼此间的表达相关性,分别获得105对基因的双变量相关系数(r12)和偏相关系数(r12.3),所有105对基因的双变量相关系数(︱r12︱)和偏相关系数(︱r12.3︱)的平均值分别为0.486 ± 0.220和0.304 ± 0.211,达到0.05的差异显著水平。其中,r12与r12.3方向相同的63对(60%),方向相反的42对(40%); ︱r12︱<︱r12.3︱的23对(21.905%),︱r12︱>︱r12.3︱的82对(78.095%); 双变量相关显著性P<0.05的76对(72.38%),P<0.01的59对(56.19%); 偏相关显著性P<0.05的21对(20%),P<0.01的16对(15.24%)。结果显示,这两条途径中的基因表达彼此相关,这为基因表达谱分析中普遍采用的前提假设“功能相关基因的表达相关”提供了进一步的实验证据,可用于挖掘、筛选和预测与橡胶生物合成相关的未知基因,为研究橡胶树产量形成的分子调控机理提供理论基础。     

Serum Uric Acid Levels and the Risk of Impaired Fasting Glucose: A Prospective Study in Adults of North China

Objective

To prospectively investigate the association between serum uric acid (SUA) level and incidence of impaired fasting glucose (IFG) in adult Chinese.

Methods

We evaluated 13,328 women and 41,350 men without diabetes and IFG. The participants were classified into quintile according to baseline level of SUA. Data were analyzed to examine the association between SUA levels and the incidence of IFG. We used Cox regression models to estimate the relative risk of IFG after adjusting for known risk factors.

Results

For men, the second quintile of SUA has the lowest cumulative incidence of IFG (29.9%); the fifth quintile of SUA has the highest cumulative incidence of IFG (35.6%). After corrected with Cox regression, the first quartile and the fourth quartile have higher cumulative incidence of IFG than the second quintile, with the HR of 1.11(1.05-1.17) and 1.07(1.01-1.13), respectively. For women, the first quartile of SUA has the lowest cumulative incidence of IFG (20.7%), while the fifth quintile of SUA has the highest cumulative incidence of IFG (30.0%). However, there is no significant difference in IFG between different quintile after adjusted with Cox regression.

Conclusions

The results of this prospective study suggest that there is a higher risk of developing IFG in association with low or high SUA concentrations for men. These relationships were independent of other known risk factors. There is no significant correlation in the risk of developing IFG in association with SUA concentrations for women. Analyses excluding participants with hypertension or with hyperlipidemia and analyses with participants stratified by age reached similar conclusion.     

Metabolic responses of HeLa cells to silica nanoparticles by NMR-based metabolomic analyses

Silica nanoparticles are increasingly used in the biomedical fields due to their excellent solubility, high stability and favorable biocompatibility. However, despite being considered of low genotoxicity, their bio-related adverse effects have attracted particular concern from both the scientific field and the public. In this study, human cervical adenocarcinoma cells (HeLa line) were exposed to 0.01 or 1.0 mg/mL of hydrophilic silica nanoparticles. The ¹H NMR spectroscopy coupled with multivariate statistical analysis were used to characterize the metabolic variations of intracellular metabolites and the compositional changes of the corresponding culture media. At the early stage of silica nanoparticles-exposure, no obvious dose–effect of HeLa cell metabolome was observed, which implied that cellular stress-response regulated the metabolic variations of HeLa cell. Silica nanoparticles induced the increases of lipids including triglyceride, LDL, VLDL and lactate/alanine ratio and the decreases of alanine, ATP, choline, creatine, glycine, glycerol, isoleucine, leucine, phenylalanine, tyrosine, and valine, which involved in membrane modification, catabolism of carbohydrate and protein, and stress-response. Subsequently, a complicated synergistic effect of stress-response and toxicological-effect dominated the biochemical process and metabolic response, which was demonstrated in the reverse changes of some metabolites including acetate, ADP, ATP, choline, creatine, glutamine, glycine, lysine, methionine, phenylalanine and valine between 6 and 48 h post-treatment of silica nanoparticles. The toxicological-effects induced by high-dosage silica nanoparticles could be derived from the elevated levels of ATP and ADP, the utilization of glucose and amino acids and the production of metabolic end-products such as glutamate, glycine, lysine, methionine, phenylalanine, and valine. The results indicated that it is important and necessary to pursue further the physiological responses of silica nanoparticles in animal models and human before their practical use. NMR-based metabolomic analysis helps to understand the biological mechanisms of silica nanoparticles and their metabolic fate, and further, it offers an ideal platform for establishing the bio-safety of existing and new nanomaterials.     

Decreased Leukocyte Telomere Length (LTL) Is Associated with Stroke but Unlikely to Be Causative

Aims

Interindividual variability in telomere length is highly heritable. Leukocyte telomere length (LTL) shortening has been shown to be associated with the process of atherosclerosis. But whether the inheritance of LTL is related to stroke is still unclear. The aim of this study was to test if telomere shortening was associated with stroke and whether this association was mainly due to inheritance or acquired cardiovascular risk factors.

Methods

Our study was focused on stroke in patients and their siblings. 450 subjects were recruited into this study: 150 patients with ischemic stroke as case group, 150 siblings of patients free of stroke (sibling group) and 150 healthy people as normal control. LTL was measured by real-time Polymerase Chain Reactions. The association between LTL and the cardiovascular risk factors was also determined.

Results

A significant decrease of LTL was found in case group when comparing with sibling (0.92±0.77 vs 1.68±1.24, p<0.001) and normal groups (0.92±0.77 vs 1.95±1.07, p<0.001), but no significant difference was found between sibling group and healthy control (p = 0.330). Shorter telomere length was independently associated with hypertension (p = 0.029, OR = 2.189, 95%CI:1.084–4.421), recent social pressure (p = 0.001, OR = 3.121, 95%CI:1.597–6.101), age (p = 0.004, OR = 1.055, 95%CI:1.017–1.093), HDL (p = 0.022, OR = 0.227, 95%CI:0.064–0.810) and diabetes (p = 0.018, OR = 3.174, 95%CI:1.221–8.252). Additionally, shortened length of telomere (p = 0.017, OR = 3.996, 95%CI:1.283–12.774) was an independent risk biomarker for stroke among case and sibling groups.

Conclusion

The present study has demonstrated that decreased LTL might be associated with ischemic stroke but unlikely to be causative.     

贵州省野生苦苣苔科物种多样性与地理分布（附录）

该研究在建立贵州省野生苦苣苔科植物名录和地理分布数据库的基础上,对其物种多样性及地理分布格局进行研究。通过文献资料结合实地调查,从物种组成、特有性、水平分布、垂直分布和相似性等方面进行分析,并采用筛除算法确定贵州苦苣苔科植物分布的热点地区。结果表明:(1)贵州省苦苣苔科植物共计2族8亚族28属153种(含种下等级),分布在75个县级行政区,有128/45个中国/贵州特有种,垂直分布以900~1300 m海拔段最为丰富。(2)通过计算省级相似性系数,发现贵州与广西的相似程度最高,最后筛选得到10个热点县,共代表了75%的苦苣苔科植物。(3)贵州省为典型的喀斯特高原山地,苦苣苔科植物种类丰富,尤其是广义马铃苣苔属、广义报春苣苔属、广义石山苣苔属和蛛毛苣苔属等,有着较高的物种多样性和区域特有性。该研究可以为贵州省苦苣苔科植物资源保护和持续利用提供理论参考。     

Directed discovery of bivalent peptide ligands to an SH3 domain

The Caenorhabditis elegans SEM-5 SH3 domains recognize proline-rich peptide segments with modest affinity. We developed a bivalent peptide ligand that contains a naturally occurring proline-rich binding sequence, tethered by a glycine linker to a disulfide-closed loop segment containing six variable residues. The glycine linker allows the loop segment to explore regions of greatest diversity in sequence and structure of the SH3 domain: the RT and n-Src loops. The bivalent ligand was optimized using phage display, leading to a peptide (PP-G(4)-L) with 1000-fold increased affinity for the SEM-5 C-terminal SH3 domain over that of a natural ligand. NMR analysis of the complex confirms that the peptide loop segment is targeted to the RT and n-Src loops and parts of the beta-sheet scaffold of this SH3 domain. This binding region is comparable to that targeted by a natural non-PXXP peptide to the p67(phox) SH3 domain, a region not known to be targeted in the Grb2 SH3 domain family. PP-G(4)-L may aid in the discovery of additional binding partners of Grb2 family SH3 domains.     

Optimizing nucleotide sequence ensembles for combinatorial protein libraries using a genetic algorithm

Protein libraries are essential to the field of protein engineering. Increasingly, probabilistic protein design is being used to synthesize combinatorial protein libraries, which allow the protein engineer to explore a vast space of amino acid sequences, while at the same time placing restrictions on the amino acid distributions. To this end, if site-specific amino acid probabilities are input as the target, then the codon nucleotide distributions that match this target distribution can be used to generate a partially randomized gene library. However, it turns out to be a highly nontrivial computational task to find the codon nucleotide distributions that exactly matches a given target distribution of amino acids. We first showed that for any given target distribution an exact solution may not exist at all. Formulated as a constrained optimization problem, we then developed a genetic algorithm-based approach to find codon nucleotide distributions that match as closely as possible to the target amino acid distribution. As compared with the previous gradient descent method on various objective functions, the new method consistently gave more optimized distributions as measured by the relative entropy between the calculated and the target distributions. To simulate the actual lab solutions, new objective functions were designed to allow for two separate sets of codons in seeking a better match to the target amino acid distribution.