虚拟视觉刺激引起幼年斑马鱼捕食行为放弃的研究

目的 当动物重复某种行为以逃避危险或获取奖励而无法成功时，会产生放弃。放弃是一种常见且基本的行为，在小鼠等模式动物中已经被广泛研究，但是其部分神经机制仍未被阐明。幼年斑马鱼适合进行全脑光学成像，是神经科学领域的重要模式生物。已经有研究者通过持续电击等消极刺激诱发斑马鱼放弃行为，然而奖励刺激能否引起斑马鱼放弃尚无报道。本文对奖励刺激引起的斑马鱼放弃行为进行了探究。方法 通过给予斑马鱼虚拟的食物视觉刺激，检验斑马鱼对虚拟食物的捕食情况，比较斑马鱼捕食频率和单次捕食时长随时间的变化。结果 虚拟的食物视觉刺激可以引起斑马鱼的捕食行为，接受25 min虚拟刺激后，8日龄以上斑马鱼的捕食频率和单次捕食时长均出现显著下降。结论 此研究丰富了斑马鱼放弃行为的研究范式，实验结果表明，缺失真实奖励的虚拟食物刺激可以诱导斑马鱼放弃捕食行为，这将进一步加深对动物放弃行为的理解，推动对其神经机制的研究。     

捕食风险对小型哺乳动物行为、神经和内分泌的影响

长期进化过程中,猎物形成了对捕食者先天的敏感性。捕食风险对小型哺乳动物的影响主要包括行为的改变、神经环路的激活和内分泌的变化。行为的改变包括抑制运动活动、降低非防御行为以及改变生活环境。一些研究用c-fos免疫组化的方法测定了大鼠在暴露于猫的气味后大脑被激活的区域,主要包括中间杏仁核、下丘脑腹内侧区、背内侧区、前乳头状核和导水管周围灰质（periaqueductal gray）。猎物对捕食应激的反应还表现在一些内分泌指标的改变,一些激素如皮质酮（Corticoserone,CORT）和促肾上腺皮质激素（Adrenocorticotropic hormone,ACTH）的含量会显著的增加,同时在一些雄性动物中,睾丸激素的含量会有所降低。捕食者和猎物的关系近年来已经成为很多学科研究的有用工具。     

鳜鱼视觉特性及其对捕食习性适应的研究：Ⅲ.视觉对猎物运动和形状的反应

作者采用行为学方法测定了伏击型凶猛鱼类鳜鱼视觉对猎物运动和形状特征的反应特性。     

动物的捕食行为

简要介绍了捕食行为研究的一些主要方向,如猎物选择、食物贮藏、捕食喂幼和捕食的节律性等,还讨论了动物的搜寻和捕食策略以及攻击方式等。     

昆虫捕食行为生态学研究进展

行为学和生态学是生命科学中正在蓬勃发展的两个分支学科,而行为生态学则是这两个年轻学科的交叉领域。它主要研究生态学中的行为机制和动物行为的存活值、适合度与进化意义[1]从理论上来讲,开展行为生态学的研究,意味着把生态学、行为学、遗传学、生理学和进化论综合起来,并运用了数学和经济学分析方法,所以很有可能在新理论、新概念和新方法的探索上取得突破性进展,也有可能引起生态学的巨大变革;从应用的角度讲,因为动物之所以能极好地适应它们的环境,主要是依靠先天的本能行为适应和后天的学习行为适应,所以深刻地了解动物行…     

鳜鱼视觉特性及其对捕食习性适应的研究

采用电生理方法研究了夜行性凶猛鱼类鳜鱼视网膜电图的一般特性,光谱敏感性和适应特性。鳜鱼的视网膜电图不显示典型的混合型视网膜特征,明视和暗视视网膜电图的光谱敏感曲线形状基本相同,峰值都在５３０ｎｍ处,没有出现Ｐｕｒｋｉｎｊｅ氏位移,明适应曲线仅出现下降型变化,暗适应过程异常缓慢,鳜鱼的视网膜仅存在单一的光感受系统,即暗视系统,不可能形成色觉,但鳜鱼视网膜具有很高的光敏感性,适于弱光视觉。     

基于在线生物监测系统的氨氮胁迫下斑马鱼行为响应

研究基于四级阻抗技术的在线生物监测系统, 参照国家地表水环境质量标准(GB3838-2002)中对 Ⅰ 类和 Ⅳ 类地表水氨氮质量标准的限值分类, 探究 0.15和1.5 mg/L氨氮胁迫下 15d 内斑马鱼(Danio rerio)行为响应, 为环境胁迫下斑马鱼的行为响应提供数据支撑。实验采用斑马鱼游动强度和速率综合行为强度来反映其行为变化, 对实验数据进行 SPSS 差异性分析、自相关分析(Autocorrelation)和自组织神经网络(Self-organization mapping net, SOM)分析。研究结果: (1)在对照组中, 行为强度数据平均值为0.69±0.13, 光周期行为强度数据(0.73±0.13)高于暗周期(0.66±0.14; P<0.01), 且光暗周期差异值为10.61%; 在氨氮胁迫组(NH₃-N, 0.15和 1.5 mg/L)实验中, 斑马鱼行为强度平均值分别为0.68±0.09和0.64±0.09, 差异值分别为 7.6%和 18.64%, 与对照组相同, 光周期行为强度明显高于暗周期(P<0.01), 证明斑马鱼的昼夜节律性。(2)在氨氮胁迫下斑马鱼行为响应最显著的特点是行为活动遭到抑制。低浓度胁迫轻微抑制, 高浓度胁迫严重抑制。在有效氨氮浓度下, 浓度越高, 抑制作用越明显(P<0.001)。(3)斑马鱼行为响应具有显著的昼夜节律现象。Autocorrelation 中正负相关峰值交替性出现, 总体表现出较为良好的对称性和以 24h 循环的周期性, 通过SOM 分析, 大部分行为强度数据与光暗周期时间分布相匹配, 说明斑马鱼的昼夜节律现象。研究表明斑马鱼行为响应具有明显的昼夜节律现象, 光周期行为强度高于暗周期, 周期为 24h 左右; 在氨氮胁迫下斑马鱼行为强度遭到抑制, 在有效氨氮浓度下浓度越高, 抑制作用越明显, 出现时间节点延迟和聚类分析异常的现象。研究使用第三代在线生物行为监测系统, 其灵敏性和精确度显著提高, 能够实时准确反映氨氮胁迫下斑马鱼的行为响应变化, 也表明在线生物监测技术在水生生物行为学研究中发挥着不可或缺的作用。     

鳜鱼视觉特性及其对捕食习性适应的研究III．视觉对猎物运动和形状的反应

作者采用行为学方法测定了伏击型凶猛鱼类鳜鱼视觉对猎物运动和形状特征的反应特性.鳜鱼对3种不同体形饵料鱼有最强的跟踪反应和攻击反应,对虾则有较强的跟踪反应而几乎没有攻击反应,对蜻蜒幼虫仅有不强的跟踪反应而完全没有攻击反应.它对低速(v≤5cm/s)一连续和等间歇不连续运动的饵料鱼有较强的跟踪反应和攻击反应,对中速和高速(v≥10cm/s)连续运动的饵料鱼有最强的跟踪反应而几乎没有或完全没有攻击反应,对中速和高速等间歇不连续运动的饵料鱼则有最强的跟踪反应和最强的攻击反应.它对不连续运动的a、b、c、d、e、f6种形状均有跟踪反应,但近距离跟踪反应的强度与形状特征有关系,对不连续运动的b、c、d3种形状完全没有攻击反应,而对不连续运动的a、e、f3种形状则有依次增强的攻击反应.鳜鱼视觉可对猎物运动进行远距离的识别,并决定其对猎物的远距离跟踪反应.且其视觉仅能对猎物的大致形状进行近距离识别,并决定其对猎物的近距离跟踪反应和攻击反应.       

麻醉剂MS-222对斑马鱼行为的影响

实验室条件下观察并测定了斑马鱼(Danio rerio)在不同MS-222浓度处理下的麻醉行为、斑马鱼在高剂量MS-222致死过程中的行为变化、MS-222对斑马鱼摄食条件反射的影响。试验表明:(1)斑马鱼的麻醉行为是一个渐变的过程,可分为不被麻醉(Ⅰ)、轻度麻醉(Ⅱ)、中度麻醉(Ⅲ)深度麻醉(Ⅳ);(2)不同MS-222浓度下斑马鱼进入不同麻醉程度的时间有差异;(3)经MS-222处理900s过程中,80-90mg·L^-1浓度组进入Ⅲ级麻醉程度并有100%的存活率,而麻醉浓度在100mg·L^-1以上时可以迅速在49s内使鱼进入Ⅲ级麻醉程度以及在178s后即可进入Ⅳ级麻醉程度,并在中度麻醉和深度麻醉的过渡中死亡,存活率不超过10%;(4)MS-222对摄食条件反射影响的试验中,光刺激-不麻醉、无光刺激-不麻醉、光刺激-麻醉、无光刺激-麻醉四组班马鱼从投喂到摄食所用时间分别为12.06±1.34s、13.20±1.13s、56.56±56.48s、36.20±25.74s,麻醉组的摄食速度慢于对照组,说明MS-222影响了斑马鱼的摄食条件反射。     

龟纹瓢虫对棉蚜的捕食行为

为探讨天敌对害虫的捕食作用机制,充分发挥生物防治的作用,本文从捕食能学角度,系统地观测了龟纹瓢虫Propylea japonica (Thunberg)对棉蚜Aphis gossypii Glover的捕食行为及影响的因素。结果表明：龟纹瓢虫对棉蚜的捕食行为依棉蚜的密度变化而逐渐转变;它在棉蚜密度高时,搜索活动下降;而在棉蚜密度低时,则搜索活动增加。产生这种行为是由于肠胃量与棉蚜遭遇率变化的综合作用结果。因此,将瓢蚜比调控在一定水平上,可以更有效地发挥以瓢治蚜的生物防治作用。     

Zebrafish larvae use stimulus intensity and contrast to estimate distance to prey

1. Download : Download high-res image (144KB)
2. Download : Download full-size image

     

Terrestrial capture of prey by the reedfish,a model species for stem tetrapods

Due to morphological resemblance, polypterid fishes are used as extant analogues of Late Devonian lobe‐finned sarcopterygians to identify the features that allowed the evolution of a terrestrial lifestyle in early tetrapods. Previous studies using polypterids showed how terrestrial locomotion capacity can develop, and how air ventilation for breathing was possible in extinct tetrapodomorphs. Interestingly, one polypterid species, the reedfish Erpetoichthys calabaricus, has been noted being capable of capturing prey on land. We now identified the mechanism of terrestrial prey‐capture in reedfish. We showed that this species uses a lifted trunk and downward inclined head to capture ground‐based prey, remarkably similar to the mechanism described earlier for eel‐catfish. Reedfish similarly use the ground support and flexibility of their elongated body to realize the trunk elevation and dorsoventral flexion of the anterior trunk region, without a role for the pectoral fins. However, curving of the body to lift the trunk may not have been an option for the Devonian tetrapodomorphs as they are significantly less elongated than reedfish and eel‐catfish. This would imply that, in contrast to the eel‐like extant species, evolution of the capacity to capture prey on land in early tetrapods may be linked to the evolution of the pectoral system to lift the anterior part of the body.     

Visual field of cultured striped trumpeter Latris lineata (Teleostei) larvae feeding on rotifer prey

The visual field of striped trumpeter Latris lineata larvae fed rotifer prey was determined from analysis of feeding behaviour in the horizontal plane. The visual field was forward and laterally directed, characterised by maximum reactive distances (distance at which the predator first detects and reacts to the prey) of 5.07 mm and 5.25 mm on days 13 and 17 post-hatching, respectively, 97% of mean larval length. This confirmed the predicted horizontal visual field, forward and laterally directed, derived from higher cone cell densities in the dorso-temporal and medial regions of the retina compared with ventral regions. The visual field of prey detection expanded laterally with ontogeny as a wider range of reactive angles was used by 17 day-old than 13 day-old larvae. Larvae displayed a saltatory searching pattern, periodically stopping to scan for prey throughout the visual field, and exhibited a side-to-side movement of the head as they approached and stopped, prior to striking at a detected prey item. Larvae on day 17 post-hatching terminated 35% of feeding sequences at the pre-strike position, at a mean distance from prey of 0.58 mm.     

Visual acuity in larval zebrafish: behavior and histology

Background

Mating plugs that males place onto the female genital tract are generally assumed to prevent remating with other males. Mating plugs are usually explained as a consequence of male-male competition in multiply mating species. Here, we investigated whether mating plugs also have collateral effects on female fitness. These effects are negative when plugging reduces female mating rate below an optimum. However, plugging may also be positive when plugging prevents excessive forced mating and keeps mating rate closer to a females' optimum. Here, we studied these consequences in the gonochoristic nematode Caenorhabditis remanei. We employed a new CO₂-sedation technique to interrupt matings before or after the production of a plug. We then measured mating rate, attractiveness and offspring number.

Results

The presence of a mating plug did not affect mating rate or attractiveness to roving males. Instead, females with mating plugs produced more offspring than females without copulatory plugs.

Conclusions

Our experiment suggests that plugging might have evolved under male-male competition but represents a poor protection against competing males in our experiment. Even if plugging does not reduce mating rate, our results indicate that females may benefit from being plugged in a different sense than remating prevention.     

Visual acuity and feeding in larval Premnas biaculeatus

Ontogenetic change in the visual acuity of Premnas biaculeatus larvae was determined both behaviourally and anatomically. Visual acuity improved substantially between early feeding (day 3 post-hatch) and the pre-settlement (day 10 post-hatch) larvae but, at both ages, the anatomically-measured visual acuity was greater than that determined behaviourally. It appears that estimated anatomical visual acuity values substantially over-estimate the functional visual acuity realized under normal conditions. The distribution of the reactive angles indicated that most frequently prey within 0 to 9° of the longitudinal larval axis elicited a feeding response at both larval ages. This suggests that stereoscopic vision is used extensively during feeding in this species. The prey capture success with rotifers ranged from 96% at 3 days post-hatch to 100% at 10 days post-hatch. These values differ markedly from previous studies on temperate species and highlight the well developed abilities of larval P. biaculeatus at a given     

Aquatic prey capture in ray-finned fishes: a century of progress and new directions

The head of ray-finned fishes is structurally complex and is composed of numerous bony, muscular, and ligamentous elements capable of intricate movement. Nearly two centuries of research have been devoted to understanding the function of this cranial musculoskeletal system during prey capture in the dense and viscous aquatic medium. Most fishes generate some amount of inertial suction to capture prey in water. In this overview we trace the history of functional morphological analyses of suction feeding in ray-finned fishes, with a particular focus on the mechanisms by which suction is generated, and present new data using a novel flow imaging technique that enables quantification of the water flow field into the mouth. We begin with a brief overview of studies of cranial anatomy and then summarize progress on understanding function as new information was brought to light by the application of various forms of technology, including high-speed cinematography and video, pressure, impedance, and bone strain measurement. We also provide data from a new technique, digital particle image velocimetry (DPIV) that allows us to quantify patterns of flow into the mouth. We believe that there are three general areas in which future progress needs to occur. First, quantitative three-dimensional studies of buccal and opercular cavity dimensions during prey capture are needed; sonomicrometry and endoscopy are techniques likely to yield these data. Second, a thorough quantitative analysis of the flow field into the mouth during prey capture is necessary to understand the effect of head movement on water in the vicinity of the prey; three-dimensional DPIV analyses will help to provide these data. Third, a more precise understanding of the fitness effects of structural and functional variables in the head coupled with rigorous statistical analyses will allow us to better understand the evolutionary consequences of intra- and interspecific variation in cranial morphology and function.     

The use of light in prey capture by the tropical pitcher plant Nepenthes aristolochioides

Nepenthes pitcher plants deploy tube-shaped pitchers to catch invertebrate prey; those of Nepenthes aristolochioides possess an unusual translucent dome. The hypothesis was tested that N. aristolochioides pitchers operate as light traps, by quantifying prey capture under three shade treatments. Flies are red-blind, with visual sensitivity maxima in the UV, blue, and green wavebands. Red celluloid filters were used to reduce the transmission of these wavebands into the interior of the pitchers. Those that were shaded at the rear showed a 3-fold reduction in Drosophila caught, relative to either unshaded control pitchers, or pitchers that were shaded at the front. Thus, light transmitted through the translucent dome is a fundamental component of N. aristolochioides' trapping mechanism.     

Differentiation of the zebrafish enteric nervous system and intestinal smooth muscle

Development of the enteric nervous system is critical for normal functioning of the digestive system. In vertebrates, enteric precursors originate from the neural crest and migrate into the digestive system. Enteric neurons enable the digestive system to sense and respond to local conditions without the need for central nervous system input. Here we describe major steps in differentiation of the zebrafish enteric nervous system. During migration and neural differentiation of enteric precursors, we identify regions of the enteric nervous system in different phases of differentiation. Early in migration, a small group of anterior enteric neurons are first to form. This is followed by an anterior to posterior wave of enteric neural differentiation later in the migratory phase. Enteric precursors continue proliferating and differentiating into the third day of embryogenesis. nNOS neurons form early while serotonin neurons form late toward the end of enteric neural differentiation. Numbers of enteric neurons increase gradually except during periods of circular and longitudinal intestinal smooth muscle differentiation.