咖啡化学成分及其生物活性研究进展

咖啡为茜草科(Rubiaceae)咖啡属(Coffea)植物,位居世界三大饮品之首,具有降低血糖、保护肝脏和神经保护等作用.咖啡化学成分类别较多,包括生物碱、酚酸类、黄酮类、萜类等.咖啡中的化学成分是发挥其生物学功能和形成特色风味的基础,对其化学成分来源和生物活性进行综述,为进一步发展咖啡产业提供依据和理论支撑.     

Dolphin swimming–a review

Research into dolphin swimming has historically been guided by false assumptions of 'effortless', 'high-speed' swimming. These assumptions have instigated the development of drag-reduction hypotheses but tests of these hypotheses have generally had little success. The autecological approach has dominated recent efforts and has been more successful. In this review we summarize results of decades of research efforts to study these creatures. (1) Drag is minimized primarily by the streamlined shape of the body and appendages, with no known contributions from compliant dampening, dermal ridges, secretions, boundary layer heating, or skin folds. All indications are that the boundary layer is turbulent. (2) Muscles for the upstroke and downstroke of swimming dolphins provide approximately equal power. (3) Output force is enhanced by insertions occurring on the long processes of the vertebrae and on the subdermal connective tissue sheath. (4) Measured swimming speeds are lower than previously believed, with maximum reported routine speeds being approximately 3 m/s. (5) Porpoising behaviour appears to be the most energetically conservative manner in which to breathe when swimming at high speed. (6) Riding surf and wind waves involves the balance between the wave slope and the weight of the animal whereas riding the bow wave involves the interaction of the pressure wave in front of a ship and the drag of the dolphin.     

细菌生物被膜核心胞外多糖靶向水解酶的生物信息挖掘北大核心

【目的】胞外多糖是生物被膜不可或缺的重要成分,在细菌致病和耐药过程中发挥着重要作用。运用酶制剂针对生物被膜的核心胞外多糖进行靶向清除,能够从根本上破坏细菌生物被膜的核心骨架,有助于战胜细菌生物被膜导致的危害。【方法】本研究针对常见致病菌生物被膜核心胞外多糖Pel、Psl、褐藻胶、N-乙酰氨基葡萄糖(Poly-β(1,6)-N-acetyl-D-glucosamine,PNAG)和纤维素,基于NCBI数据库中丰富的基因序列信息,筛选靶向生物被膜核心胞外多糖的水解酶,进一步运用phyre2、SWISS-MODEL等生物信息工具,分析了这些水解酶的理化性质、遗传进化、功能域及三维结构。【结果】筛选获得了153个靶向生物被膜核心胞外多糖的水解酶及其序列信息。其中,靶向Pel胞外多糖的水解酶共30个,属于糖苷水解酶114家族(glycoside-hydrolase family GH114);靶向Psl胞外多糖的水解酶共25个,属于糖苷水解酶超家族(glyco_hydro super family);靶向褐藻胶胞外多糖的水解酶共33个,属于褐藻胶裂解酶超家族(Alg Lyase superfamily);靶向PNAG胞外多糖的水解酶共30个,属于糖苷水解酶13家族(glycoside-hydrolase family GH13);靶向纤维素胞外多糖的水解酶共35个,属于糖苷水解酶8家族(glycosyl hydrolases family GH8)。【结论】这些水解酶菌具备靶向瓦解生物被膜核心胞外多糖的潜力,亟待进一步开发与应用。本研究提供了迄今为止最为全面的生物被膜核心胞外多糖水解酶序列组成及生物信息,为生物被膜的精准预防和靶向控制奠定扎实的数据基础。     

Comparing genetic variants detected in the 1000 genomes project with SNPs determined by the International HapMap Consortium

Single-nucleotide polymorphisms (SNPs) determined based on SNP arrays from the international HapMap consortium (HapMap) and the genetic variants detected in the 1000 genomes project (1KGP) can serve as two references for genomewide association studies (GWAS). We conducted comparative analyses to provide a means for assessing concerns regarding SNP array-based GWAS findings as well as for realistically bounding expectations for next generation sequencing (NGS)-based GWAS. We calculated and compared base composition, transitions to transversions ratio, minor allele frequency and heterozygous rate for SNPs from HapMap and 1KGP for the 622 common individuals. We analysed the genotype discordance between HapMap and 1KGP to assess consistency in the SNPs from the two references. In 1KGP, 90.58% of 36,817,799 SNPs detected were not measured in HapMap. More SNPs with minor allele frequencies less than 0.01 were found in 1KGP than HapMap. The two references have low discordance (generally smaller than 0.02) in genotypes of common SNPs, with most discordance from heterozygous SNPs. Our study demonstrated that SNP array-based GWAS findings were reliable and useful, although only a small portion of genetic variances were explained. NGS can detect not only common but also rare variants, supporting the expectation that NGS-based GWAS will be able to incorporate a much larger portion of genetic variance than SNP arrays-based GWAS.     

ADOLESCENT AND PARENTAL PERCEPTIONS OF MEDICAL DECISION‐MAKING IN HONG KONG

Objectives: To investigate whether Chinese adolescents in Hong Kong share similar perceptions with their Western counterparts regarding their capacity for autonomous decision‐making, and secondarily whether Chinese parents underestimate their adolescent children's desire and capacity for autonomous decision‐making. Method: ‘Healthy Adolescents’ and their parents were recruited from four local secondary schools, and ‘Sick Adolescents’ and their parents from the pediatric wards and outpatient clinics. Their perceptions of adolescents' understanding of illnesses and treatments, maturity in judgment, risk‐taking, openness to divergent opinions, pressure from parents and doctors, submission to parental authority and preference for autonomy in medical decision‐making are surveyed by a 50‐item questionnaire on a five‐point Likert scale. Results: Findings indicate that Chinese adolescents aged 14–16 perceive themselves to possess the necessary cognitive abilities and maturity in judgment to be autonomous decision‐makers like their Western counterparts. Paradoxically, although they hesitate to assert their autonomy, they are also unwilling to surrender that autonomy to their parents even under coercion or intimidation. Parents tend to underestimate their adolescents' preferences for making autonomous decisions and overestimate the importance of parental authority in decision‐making. Conclusion: ‘14‐and‐above’ Chinese adolescents in Hong Kong perceive themselves as capable of autonomous decision‐making in medically‐related matters, but hesitate to assert their autonomy, probably because of the Confucian values of parental authority and filial piety that are deeply embedded in the local culture.     

浅谈我国高校教师激励机制建设

分析了我国高校教师的激励工作在社会外部环境、人员选用制度、业绩评估方法、报酬制度、激励方式等方面存在的问题,提出应从实施高校教师激励制度所要遵循的原则出发,选择正确的激励方法,构建合理的激励机制。     

A splice variant of PGRP-LC required for expression of antimicrobial peptides in Anopheles gambiae

Members of the peptidoglycan recognition protein （PGRP） family play essential roles in different manifestations of immune responses in insects. PGRP-LC, one of seven members of this family in the malaria vector Anopheles gambiae produced several spliced variants. Here we show that PGRP-LC, and not other members of the PGRP family nor the six members of the Gram-negative binding protein families, is required for the expression of antimicrobial peptide genes （such as CEC1 and GAM1） under the control of the Imd-Rel2 pathway in an A. gambiae cell line, 4a3A. PGRP-LC produces many splice variants that can be classified into three sub-groups （LC1, LC2 and LC3）, based on the carboxyl terminal sequences. RNA interference against one LC1 sub-group resulted in dramatic reduction of CEC1 and GAM1. Over-expression of LCla and to a lesser extent LC3a （a member of the LC1 and LC3 sub-group, respectively） in the 4a3A cell line enhances the expression of CEC1 and GAM1. These results demonstrate that the LC1-subgroup splice variants are essential for the expression of CEC1 and GAM1 in A. gambiae cell line.