Convenient and simple homologation of Nα-urethane protected α-amino acids to their β-homologues with concomitant pentafluorophenyl ester formation

Summary The Wolff rearrangement of α-aminodiazoketones derived fromN ^α-urethane protected α-amino acids in the presence of pentafluorophenol catalyzed by silver acetate at low temperature results in the homologation of Fmoc-/Boc-/Z-α-amino acids to β-amino acids with concomitant formation of the corresponding pentafluorophenyl esters in good yield and purity.     

Encoding repetition rate and duration in the inferior colliculus of the big brown bat,Eptesicus fuscus

1. Encoding of temporal stimulus parameters by inferior collicular (IC) neurons of Eptesicus fuscus was studied by recording their responses to a wide range of repetition rates (RRs) and durations at several stimulus intensities under free field stimulus conditions. 2. The response properties of 424 IC neurons recorded were similar to those reported in previous studies of this species. 3. IC neurons were classified as low-pass, band-pass, and high-pass according to their preference for RRs and/or durations characteristic of, respectively, search, approach, or terminal phases of echolocation. These neurons selectively process stimuli characteristic of the various phases of hunting. 4. Best RRs and best durations were not correlated with either the BFs or recording depths This suggests that each isofrequency lamina is capable of processing RRs and durations of all hunting phases. 5. Responses of one half of IC neurons studied were correlated with the stimulus duty cycle. These neurons may preferentially process terminal phase information when the bat's pulse emission duty cycle increases. 6. While the stimulus RR affected the dynamic range and overall profile of the intensity rate function, only little effect was observed with different stimulus durations.     

Responses of plant phenology to nitrogen addition: a meta‐analysis

Phenology is one of the most sensitive processes of plant in response to global change. Anthropogenic activities have considerably increased nitrogen (N) deposition, which significant affects plant phenology. Although numerous individual studies have been conducted, it remains controversial how N addition affects phenological stages, and a comprehensive understanding of how plant phenology responds to external N inputs remains elusive. To reconcile the differences, we conducted a meta‐analysis of 117 species to examine the responses of plant phenology to N addition in terrestrial ecosystems, and assessed variations in their responses in relation to ecosystem types, functional groups, and environmental conditions. Our results showed that plant phenology changed significantly after N addition, and phenology time delayed and phenology duration shortened significantly across all biomes except fruiting duration, but varied with biome types. The phenology change in cropland was more dramatical than in grassland after N addition, even in opposite directions. The response of phenological stages to N addition was consistent in two pollination types except the flowering time, the flowering time had no change in anemophilous but significantly delayed in entomophilous. In addition, the response of phenology to N addition was discrepancy among functional groups, the phenology time advanced and duration shortened in sedge, while phenology time delayed and duration shortened in other groups, and the phenology change in legume was larger than grass and forbs. We also found that environmental factors had little effects on the response of plant phenology to N addition, but significant correlation was found between the response ratios of different phenological stages. Our study suggested that phenology was sensitive to N deposition at many phenological stages, and changes in phenology may be smaller with community biodiversity increasing at ecosystem level.     

Relative efficiency of pitfall trapping and hand-collecting from plots for sampling of millipedes

Millipedes were sampled by hand-collecting from plots and by pitfall trapping at three forest sites in central Tasmania. Seven days of pitfall trapping each month over one year was less efficient than four weeks of hand-collecting in autumn, yielding fewer species and fewer specimens per working day in the field. Hand-collecting is likely to provide more accurate data on species diversity and relative abundance for a range of litter invertebrates.     

Organization of meissner corpuscles in the glabrous skin of monkey and cat

Abstract

Purpose: Motor imagery, the process of imagining a physical action, has been shown to facilitate the excitability of spinal anterior horn cells. In the acute phase after a stroke, the excitability of spinal anterior horn cells is significantly reduced, which leads to motor deficits. This loss of movement can be prevented by increasing the excitability of spinal anterior horn cells immediately following an injury. Motor imagery is an effective method for facilitating the excitability of spinal anterior horn cells in patients with impaired movement; however, the optimal duration for motor imagery is unclear.

Materials and Methods: To investigate time-dependent changes in spinal anterior horn cell excitability during motor imagery, healthy adult participants were recruited to measure the F-wave, an indicator of anterior horn cell excitability. F-waves were measured from participants at baseline, during motor imagery, and post-motor imagery. During motor imagery, participants imagined isometric thenar muscle activity at 50% maximum voluntary contraction for 5?min. F-waves were measured at 1, 3, and 5?min after beginning motor imagery and analysed for persistence and F/M amplitude ratio.

Results: Persistence and F/M amplitude ratios at 1- and 3-min after motor imagery initiation were significantly greater than at baseline. The persistence and F/M amplitude ratio at 5-min after motor imagery initiation, however, was comparable to baseline levels.

Conclusion: Therefore, 1 to 3?min of motor imagery is likely sufficient to facilitate the excitability of spinal anterior horn cells.     

Independent coding of movement duration in a repetitive non-visually guided movement

The aim of the present study was to examine the association of high blood lactate levels, induced with a maximal cycling or with an intravenous infusion, with spinal cord excitability. The study was carried out on 17 male athletes; all the subjects performed a maximal cycling test on a mechanically braked cycloergometer, while 6 of them were submitted to the intravenous infusion of a lactate solution (3?mg/kg in 1?min). Before the exercise or the injection, also at the end as well as 5 and 10?min after the conclusion, venous blood lactate was measured and excitability of the spinal α-motoneurons was evaluated by using the H reflex technique. In both experimental conditions, it has been observed that an exhaustive exercise is associated with a strong increase of blood lactate (but not of blood glucose) and with a significant reduction of spinal excitability. Since a similar augment of blood lactate induced by an intravenous infusion, in subjects not performing any exercise, is not associated with significant changes of spinal excitability, it can be concluded that the increase of blood lactate levels during a maximal exercise is not per se capable of modifying the excitability of spinal α-motoneurons.     

蚜茧蜂对多世代棉蚜生长发育与繁殖的胁迫作用

天敌不仅直接捕食或寄生害虫,而且还能通过胁迫作用改变害虫的生长发育与繁殖,间接地影响害虫的适合度。本文以棉田重要害虫棉蚜Aphis gossypii Glover及其寄生性天敌蚜茧蜂Lysiphlebia japonica Ashmead为对象,在相同的大气二氧化碳浓度环境中研究了直接放蚜茧蜂和通过笼罩间接放蚜茧蜂所产生的胁迫作用对连续3代棉蚜生长发育与繁殖的影响。结果表明,直接放蚜茧蜂的胁迫作用使第1代棉蚜繁殖率明显下降;第2代如果继续受到寄生蜂的直接胁迫,棉蚜生长发育与繁殖得到恢复,但受到持续间接胁迫作用却使棉蚜繁殖率明显下降;第3代如果棉蚜继续受到寄生蜂的直接或间接胁迫,与当代或与前一代后一直未受到寄生蜂胁迫作用相比,其整个若虫发育历期明显延长或缩短,但其繁殖率均明显下降。我们的结果显示:评价天敌作用时,不仅仅考虑其直接的捕食或寄生作用,还应该综合考虑其"间接"的生态效应。     

二疣犀甲室内生物学特性及形态观察

【目的】 对二疣犀甲Oryctes rhinoceros室内生物学特性及形态进行系统观察。【方法】 在室内一定条件下（温度26±1℃, RH 75%~95%, 光周期10L∶14D）以牛粪和锯末混合物（4∶1, m/m）饲养二疣犀甲各虫态, 每6 h观察记录各虫态的形态学特征及其发育情况, 并测量各虫态的重要发育指标, 如体长、 体宽、 体重等。【结果】 二疣犀甲属于全变态昆虫, 一生经历4个虫态, 分别为卵、 幼虫、 蛹和成虫。二疣犀甲卵的发育历期平均为8.88 d, 整个幼虫期平均需156.82 d, 预蛹和蛹的平均发育历期分别为9.45 d和33.75 d, 二疣犀甲完成一个世代需要326~455 d。1龄幼虫体长为4.16 mm, 体重0.64 g, 之后随龄期迅速增加, 至3龄时, 体长为65.66 mm, 体重增加到12.14 g。蛹期平均体长为51.62 mm, 体重为9.72 g。早期羽化的成虫个体较晚期羽化的大, 表现为体长、 体宽、 角长及体重存在显著差异(P≤0.05)。二疣犀甲成虫具有雌雄二型现象, 子代性比(雌∶雄)为1.23∶1。【结论】 二疣犀甲O. rhinoceros是椰子等棕榈科植物的重要害虫, 基础生物学和形态学研究是防控技术研究的基础, 本研究结果可为生产上防治该虫提供理论依据。     

Teen at Work: The Burden of a Double Shift on Daily Activities

The purpose of this study was to the evaluate time spent by working and nonworking adolescents on daily activities (work, home duties, school, transportation, other activities, leisure, sleep, and naps). Twenty-seven students, 8 male workers, 8 female workers, 5 male nonworkers, and 6 female nonworkers, ages 14–18 yrs participated in the study. They attended evening classes Monday–Friday (19:00–22:30 h) in a public school in the city of São Paulo, Brazil. The students answered a comprehensive questionnaire on the characterization of their life, work, and health conditions. Simultaneously, they wore actigraphs (Ambulatory Monitoring, Inc.) and completed a diary of their daily activities (time spent at work, on home duties, commuting, leisure, other activities) for a minimum of 10 to a maximum of 17 consecutive days. The means of the variables were tested for differences by a two-factor (work and sex) ANOVA and Student-t test applied to pair-wise samples (weekdays and weekends). The average duration during weekdays of working time was 7 h 09 min and home duties 0 h 48 min. As for commuting time, there was a work effect [F_(1,23) = 4.9; p = 0.04]; mean commuting time was 2 h 22 min for workers (males and females) and 1 h 25 min for nonworkers. There was a significant difference between workers and nonworkers [F_(1,23) = 4.6; p = 0.04] regarding extra-cirricular class activities; workers spent a mean of 3 min/day on them as opposed to 1 h 14 min by nonworkers. The average daily time spent on leisure activities by workers was 6 h 31 min; whereas, for nonworkers it was 7 h 38 min. Time spent in school amounted to 2 h 47 min for workers in comparison to 3 h 22 min by nonworkers. There was a significant work effect upon sleep [F_(1,23) = 10.0; p < 0.01]. The work effect upon nighttime sleep duration was significant [F_(1,23) = 16.7; p < 0.01]. Male workers showed a mean night sleep of 6 h 57 min and female workers 07 h 15 min. The average nighttime sleep duration for nonworkers was 9 h 06 min. There was a significant interactive effect between work and sex [F_(1,23) = 5.6; p = 0.03] for naps. Female workers showed took shortest nap on average (36 min; SD = 26 min), and female nonworkers the longest naps (1 h 45 min; SD = 35 min). Study and employment exert significant impact on the life and activities of high school students. Work affects sleep and nap duration plus the amount of time spent in school and other extra-curricular activities.     

Interaction of Phospholipid and Antibiotic Ionophores,Gramicidin A′ and Valinomycin,in Mixed Monolayers

To obtain information concerning the effects of ionophores on biological membranes, the thermotropic behavior of ionophores such as gramicidin A′ and valinomycin in monolayers was investigated by measuring the surface pressure–area (π–A) and the surface viscosity-area (η_s–A) isotherms. Gramicidin A’ had an isotherm having the transition from a liquid-expanded through an intermediate to a condensed state, while valinomycin had a concave isotherm. The π–A isotherms for two ionophores had a decremental shift with increasing temperatures, depending upon a variety of their molecular structures. A distinct difference between the two ionophores in η_s–A isotherms was observed. In addition, the interaction of dimyristoylphosphatidylcholine (DMPC) with the two ionophores in mixed monolayers was investigated. When valinomycin was mixed with DMPC, no deviation from the additivity rule occurred below and above the phase transition temperature T_c of DMPC. However, when gramicidin A′ was mixed with DMPC, a considerable negative deviation from ideal mixing occurred below T_c, suggesting the formation of an irregular ripple structure.