日本伏翼的翼型、回声定位信号及出飞时间特征

对日本伏翼的翼型、回声定位信号及晚间出飞时间进行研究。结果表明,日本伏翼的翼型具有高翼载、低翼展比和中等偏高的翼型特征。日本伏翼发出具有1 - 2 个谐波结构的调频型(FM)回声定位信号叫声,其叫声时程、主频率的平均值分别为3.26 ms 和56. 27 kHz,所有叫声特征参数,个体间变异系数CVb 比个体内变 异系数CVw 大。日本伏翼的晚间出飞时间具有明显月变化,与当地日落时间、气温呈现显著相关。通过与文献比较,发现日本伏翼的回声定位信号特征与录音状态、飞行生境有关;此外,晚间出飞时间存在一定的地理差异。本研究结果将为蝙蝠回声定位信号特征的种属特异性及其生境选择的进一步研究提供有用的信息。     

蝙蝠回声定位声波的可塑性及其生态适应

蝙蝠通过调节回声定位声波特征来满足自身的感官需求,表现出回声定位声波的可塑性及其对生态环境与需求的适应。声波频率、强度、脉冲持续时间和间隔时间等特征与蝙蝠所处的生态位密切相关,声波可塑性在蝙蝠进化过程中起着至关重要的作用。本文结合马铁菊头蝠(Rhinolophus ferrumequinum)和大趾鼠耳蝠(Myotis macrodactylus)回声定位声波可塑性的研究,从回声定位声波的方向性、目标距离、环境复杂度和应对干扰4个方面总结了蝙蝠如何通过改变回声定位声波特征来满足自身在导航和捕捉猎物过程中的感官需求与生态适应,并阐述了回声定位声波可塑性的研究现状,为开展蝙蝠声学和行为学研究提供参考。     

同地共栖四种蝙蝠食性和回声定位信号的差异及其生态位分化

本研究于 2 0 0 2年 5月初至 2 0 0 3年 9月中旬在北京房山区霞云岭四合村蝙蝠洞进行 ,分析了共栖同一山洞四种蝙蝠的形态特征、食性和回声定位信号。大足鼠耳蝠食谱中以宽鳍等三种鱼为主 (体积百分比为5 3% ) ,回声定位主频 4 1 87± 1 0 7kHz;马铁菊头蝠主要掠捕鳞翅目昆虫 (73% ) ,恒频叫声主频 74 70± 0 13kHz ;中华鼠耳蝠以近地面或在地表活动的鞘翅目昆虫步甲类和埋葬甲类为主要食物 (6 5 4 % ) ,声脉冲主频较低 35 73± 0 92kHz;白腹管鼻蝠捕食花萤总科和瓢虫科等鞘翅目昆虫 (90 % ) ,回声定位信号主频为 5 9 4 7±1 5 0kHz。结果证实同地共栖四种蝙蝠种属特异的回声定位叫声和形态结构的差异 ,以及不同的捕食生境和捕食策略 ,导致取食生态位分离是四种蝙蝠同地共栖的原因     

无尾蹄蝠的回声定位声波特征及分析

采用超声波监听仪U30录制无尾蹄蝠自由飞行状态的回声定位声波,经Batsound3.0分析,其声波为高频(145.4±10.9kHz)、宽带(62.6±9.2kHz)、具两个谐波的短(1.67±0.4ms)FM型,不同于蹄蝠科其他蝙蝠的CF型,表明该科内物种声波类型存在多态性。头骨的形态测定分析支持其通过鼻腔发射声波,与蹄蝠科其他蝙蝠一致,表明该科内声波发射方式的单一性。适应环境的选择压力及翼型和声波的适应性可能是其选择FM型叫声的重要原因。     

Factors regulating the contributions of fixed nitrogen by pasture and crop legumes to different farming systems of eastern Australia

On-farm and experimental measures of the proportion (%Ndfa) and amounts of N₂ fixed were undertaken for 158 pastures either based on annual legume species (annual medics, clovers or vetch), or lucerne (alfalfa), and 170 winter pulse crops (chickpea, faba bean, field pea, lentil, lupin) over a 1200 km north-south transect of eastern Australia. The average annual amounts of N₂ fixed ranged from 30 to 160 kg shoot N fixed ha^–1 yr^–1 for annual pasture species, 37–128 kg N ha^–1 yr^–1 for lucerne, and 14 to 160 kg N ha^–1 yr^–1 by pulses. These data have provided new insights into differences in factors controlling N₂ fixation in the main agricultural systems. Mean levels of %Ndfa were uniformly high (65–94%) for legumes growing at different locations under dryland (rainfed) conditions in the winter-dominant rainfall areas of the cereal-livestock belt of Victoria and southern New South Wales, and under irrigation in the main cotton-growing areas of northern New South Wales. Consequently N₂ fixation was primarily regulated by biomass production in these areas and both pasture and crop legumes fixed between 20 and 25 kg shoot N for every tonne of shoot dry matter (DM) produced. Nitrogen fixation by legumes in the dryland systems of the summer-dominant rainfall regions of central and northern New South Wales on the other hand was greatly influenced by large variations in %Ndfa (0–81%) caused by yearly fluctuations in growing season (April–October) rainfall and common farmer practice which resulted in a build up of soil mineral-N prior to sowing. The net result was a lower average reliance of legumes upon N₂ fixation for growth (19–74%) and more variable relationships between N₂ fixation and DM accumulation (9–16 kg shoot N fixed/t legume DM). Although pulses often fixed more N than pastures, legume-dominant pastures provided greater net inputs of fixed N, since a much larger fraction of the total plant N was removed when pulses were harvested for grain than was estimated to be removed or lost from grazed pastures. Conclusions about the relative size of the contributions of fixed N to the N-economies of the different farming systems depended upon the inclusion or omission of an estimate of fixed N associated with the nodulated roots. The net amounts of fixed N remaining after each year of either legume-based pasture or pulse crop were calculated to be sufficient to balance the N removed by at least one subsequent non-legume crop only when below-ground N components were included. This has important implications for the interpretation of the results of previous N₂ fixation studies undertaken in Australia and elsewhere in the world, which have either ignored or underestimated the N present in the nodulated root when evaluating the contributions of fixed N to rotations.     

两种鼠耳蝠回声定位叫声的比较

对鼠耳蝠属两种蝙蝠飞行状态下的声发射进行了比较研究.结果表明两种鼠耳蝠声发射信号的声谱图都呈调频(FM)型,但在波形及频率范围上有明显差异.大鼠耳蝠(四川亚种)的声脉冲宽度很小(1.6±0.3ms),能率环较低(4.0%),其主频率(DF=44.6±4.3kHz)也较低;而水鼠耳蝠的声脉冲宽度较大(4.2±1.6ms),能率环(9.6%)及主频率(DF=83.0±4.0kHz)也较高.文中结合两种蝙蝠的形态及食性分析了回声定位对捕食生境及捕食策略的适应性.     

Can two streams of auditory information be processed simultaneously? Evidence from the gleaning bat Antrozous pallidus

A tenet of auditory scene analysis is that we can fully process only one stream of auditory information at a time. We tested this assumption in a gleaning bat, the pallid bat (Antrozous pallidus) because this bat uses echolocation for general orientation, and relies heavily on prey-generated sounds to detect and locate its prey. It may therefore encounter situations in which the echolocation and passive listening streams temporally overlap. Pallid bats were trained to a dual task in which they had to negotiate a wire array, using echolocation, and land on one of 15 speakers emitting a brief noise burst in order to obtain a food reward. They were forced to process both streams within a narrow 300 to 500 ms time window by having the noise burst triggered by the bats initial echolocation pulses as it approached the wire array. Relative to single task controls, echolocation and passive sound localization performance was slightly, but significantly, degraded. The bats also increased echolocation interpulse intervals during the dual task, as though attempting to reduce temporal overlap between the signals. These results suggest that the bats, like humans, have difficulty in processing more than one stream of information at a time.     

An on/off resonance rotating frame relaxation experiment to monitor millisecond to microsecond timescale dynamics

Rotating frame relaxation experiments in proteins are used to study slow motions on the microsecond to millisecond timescale. An on/off resonance rotating frame relaxation experiment (R(1)(rho)) has been developed that incorporates adiabatic rotations into a R(1)(rho)-R(1) constant relaxation time experiment with weak radio frequency field strengths in order to effectively lock the magnetization over a wide range of (15)N frequencies. The new pulse sequence allows the measurement of a wide range of chemical exchange timescales on the order of 1.0 to 0.05 ms over an asymmetric bandwidth from +1.7omega(l) to -0.5omega(l) in a single experiment. A total bandwidth of +/-l.7omega(l) is obtained by performing the experiment a second time with a reversed adiabatic rotation.     

Laser‐enhanced drug delivery of antiretroviral drugs into human immunodeficiency virus‐1 infected TZMbl cells

The introduction of highly active antiretroviral therapy (HAART) has significantly increased life expectancy and improved management of the human immunodeficiency virus‐1 (HIV‐1) disease globally. This well‐established treatment regime has shown to reduce viral capacity to undetectable limits when using traditional clinical assays. The establishment of viral reservoirs during the early stages of infection are the major contributors to failure of the current regimens to eradicate HIV‐1 infection since the reservoirs are not affected by antiretroviral drugs (ARVs). Therefore, advanced modification of the present treatment and investigation of novel antiretroviral drug delivery system are needed. The aim of this study was to use femtosecond (fs) laser pulses to deliver ARVs into HIV‐1 infected TZMbl cells. Different ARVs were translocated into TZMbl cells using fs pulsed laser (800 nm) with optimum power of 4 μW and 10 ms laser to cell exposure time. Changes in cellular processes were evaluated using cellular morphology, viability, cytotoxicity and luciferase activity assays. Cells treated with the laser in the presence of ARVs showed a significant reduction in viral infectivity, cell viability and an increase in cytotoxicity. This study demonstrated that fs laser pulses were highly effective in delivering ARVs into HIV‐1 infected TZMbl cells, causing a significant reduction in HIV‐1 infection.     

Ultrashort electric pulse induced changes in cellular dielectric properties

The interaction of nanosecond duration pulsed electric fields (nsPEFs) with biological cells, and the models describing this behavior, depend critically on the electrical properties of the cells being pulsed. Here, we used time domain dielectric spectroscopy to measure the dielectric properties of Jurkat cells, a malignant human T-cell line, before and after exposure to five 10ns, 150kV/cm electrical pulses. The cytoplasm and nucleoplasm conductivities decreased dramatically following pulsing, corresponding to previously observed rises in cell suspension conductivity. This suggests that electropermeabilization occurred, resulting in ion transport from the cell's interior to the exterior. A delayed decrease in cell membrane conductivity after the nsPEFs possibly suggests long-term ion channel damage or use dependence due to repeated membrane charging and discharging. This data could be used in models describing the phenomena at work.