Differences in dinucleotide frequencies of thermophilic genes encoding water soluble and membrane proteins

The occurrence frequencies of the dinucleotides of genes of three thermophilic and three mesophilic species from both archaea and eubacteria were investigated in this study. The genes encoding water soluble proteins were rich in the dinucleotides of purine dimers, whereas the genes encoding membrane proteins were rich in pyrimidine dimers. The dinucleotides of purine dimers are the counterparts of pyrimidine dimers in a double-stranded DNA. The purine/pyrimidine dimers were favored in the thermophiles but not in the mesophiles, based on comparisons of observed and expected frequencies. This finding is in agreement with our previous study which showed that purine/pyrimidine dimers are positive factors that increase the thermal stability of DNA. The dinucleotides AA, AG, and GA are components of the codons of charged residues of Glu, Asp, Lys, and Arg, and the dinucleotides TT, CT, and TC are components of the codons of hydrophobic residues of Leu, Ile, and Phe. This is consistent with the suitabilities of the different amino acid residues for water soluble and membrane proteins. Our analysis provides a picture of how thermophilic species produce water soluble and membrane proteins with distinctive characters: the genes encoding water soluble proteins use DNA sequences rich in purine dimers, and the genes encoding membrane proteins use DNA sequences rich in pyrimidine dimers on the opposite strand.     

Does installation of the backstroke start device reduce 15-m start time in swimming?

The purpose of this study was to determine the installation of the backstroke start device reduces 15-m time. Thirteen college swimmers participated in this study. The aerial start and underwater motions were recorded with two digital video cameras. The center of mass (CM) of the swimmer, angular displacements and velocities of the shoulder, hip and knee joints were calculated. As an indicator of performance, the 5- and 15-m times were measured. The 5- and 15-m times in the backstroke start device condition were significantly shorter than in the non-backstroke start device condition. The vertical velocities of the CM at hand-off and toe-off in the backstroke start device condition were significantly greater than in the non-backstroke start device condition, while there was no significant difference in the CM horizontal velocity at toe-off. As a result, the height of the great trochanter at entry of the fingertips, with the backstroke start device, was 15 cm higher than in the non-backstroke start device condition. In addition, the CM horizontal velocities at 5 m in the backstroke start device condition were significantly greater than those of the non-backstroke start device. Thus, the use of the backstroke start device may reduce the 15-m time by diminution of the entry area.     

A quantitative evaluation of the high elbow technique in front crawl

Many coaches often instruct swimmers to keep the elbow in a high position (high elbow position) during early phase of the underwater stroke motion (pull phase) in front crawl, however, the high elbow position has never been quantitatively evaluated. The aims of this study were (1) to quantitatively evaluate the “high elbow” position, (2) to clarify the relationship between the high elbow position and required upper limb configuration and (3) to examine the efficacy of high elbow position on the resultant swimming velocity. Sixteen highly skilled and 6 novice male swimmers performed 25 m front crawl with maximal effort and their 3-dimensional arm stroke motion was captured at 60 Hz. An attempt was made to develop a new index to evaluate the high elbow position (I_he: high elbow index) using 3-dimensional coordinates of the shoulder, elbow and wrist joints. I_he of skilled swimmers moderately correlated with the average shoulder internal rotation angle (r = ?0.652, P < 0.01) and swimming velocity (r = ?0.683, P < 0.01) during the pull phase. These results indicate that I_he is a useful index for evaluating high elbow arm stroke technique during the pull phase in front crawl.     

The influence of audience and monetary reward on the putting kinematics of expert and novice golfers

We investigated changes in movement kinematics and attentional focus when expert and novice golfers performed a golf-putting task under pressure. Six male professional golfers and five male novice golfers performed 100 acquisition trials, followed by 10 trials in the pressure condition with a performance-contingent cash reward and small audience. After the 10 trials in the pressure condition, participants answered a questionnaire concerning attentional focus during both types of trial, including such aspects as conscious control of movements and the effects of distraction. A pressure manipulation check revealed a modest increase in physiological arousal, in that heart rate increased by about 10 bpm although state anxiety did not increase. A two-dimensional analysis of movement kinematics revealed that the amplitudes of arm and club movements decreased on the backswing in the pressure condition. Arm and club movement speed decreased on the foreswing in both experts and novices. Furthermore, neither experts nor novices changed their attentional focus in the pressure condition. Whereas previous studies of "choking under pressure" focused on attentional changes, the kinematic changes found in the present study were possibly caused by the influences of strategy modification and/or emotional response. Choking phenomena can be explained by attentional changes, along with the influences of strategy modification and/or emotional response under pressure.     

稻瘟病菌原生质体制备条件优化实验研究

原生质体的制备一直是现代分子生物学研究的重要内容。以稻瘟病菌作为供试菌株,优化了其原生质体的制备条件。优化的原生质体制备条件包括:使用新鲜的菌丝进行接种;加入玻璃珠一起培养,通过振荡使菌丝体破碎分离以获得更多的生长点;菌悬液继续加入新鲜培养液进行培养;原生质体沉淀时选择3 000r/min离心10min,保证最大限度地收集原生质体。实验证明,通过这4个条件优化后,原生质体的产量有了极大的提高,每毫升酶液可制备10 8～109个原生质体。     

CHEⅢ型脉冲电泳仪获得清晰电泳效果的实验探索

CHEF Ⅲ型脉冲电泳仪是微生物种类鉴定、DNA大分子分离等基础科学研究中一个不可或缺的重要工具。该仪器可以快速、高效、准确地分离200 kb到6 Mb的DNA分子。因此,在染色体数目及染色体大小的确定、核型分析、遗传图谱分析、同源性检测分析等方面有关键性的作用。然而在实验过程中要使DNA分子完全、有效地分离,得到清晰、高效的条带却并非易事。本实验基于这些问题,经过一系列的探索研究,找到了稻瘟病菌及分子量标准酵母菌染色体分离所需要的最适条件,该条件能为分离其他真菌染色体提供借鉴与参考。     

A novel comparison between standard and new testing procedures to assess shock absorbency of third generation artificial turfs

This study aims to re-examine to what extent the testing procedure of the Artificial Athlete Berlin (DIN18032) is a valid evaluation method to assess the shock absorbency of third generation artificial turf (3-g turf) and to establish a new testing procedure, which precisely reflects the acute load by human sports action. The DIN test was conducted for 3-g turfs with different infill component. The baseline of the load of acute human sports action was obtained from the ground reaction force underneath the standard type of 3-g turf sample during landing from a 55-cm height with minimal shock attenuation. For reproducing the force similar to such a hard landing, a testing rig was developed and the same 3-g turf samples were tested. The DIN test failed to distinguish most types of 3-g turf and was found to be inappropriate to evaluate the shock absorbency of the 3-g turf mainly due to bouncing actions of the test foot on measured samples. In contrast, the newly developed testing rig succeeded in illustrating the differences of shock attenuation properties among most types of 3-g turfs in a high loading condition. In terms of players’ safety, the necessity of high loading test using an alternative testing procedure was highlighted.     

The Role of Educational Research in Educational Improvements

Educational research is an undertaking to review and improve educational practice. In one case, educational practitioners conduct research by themselves in order to review their own practices, while in another, non-practitioners undertake the research. Educational practice here will refer to the individual instructional activities of school teachers on the one hand and the organized activities or programmes of educational institutions or educational systems on the other.