Secondary eyes mediate the response to looming objects in jumping spiders (Phidippus audax,Salticidae)

Some species have sensory systems divided into subsystems with morphologically different sense organs that acquire different types of information within the same modality. Jumping spiders (family Salticidae) have eight eyes. Four eyes are directed anteriorly to view objects in front of the spider: a pair of principal eyes track targets with their movable retinae, while the immobile anterior lateral (AL) eyes have a larger field of view and lower resolution. To test whether the principal eyes, the AL eyes, or both together mediate the response to looming stimuli, we presented spiders with a video of a solid black circle that rapidly expanded (loomed) or contracted (receded). Control spiders and spiders with their principal eyes masked were significantly more likely to back away from the looming stimulus than were spiders with their AL eyes masked. Almost no individuals backed away from the receding stimulus. Our results show that the AL eyes alone mediate the loom response to objects anterior to the spider.     

群体大小对青幼鱼群体特征的影响

为考察群体大小对青幼鱼(Mylopharyngodon piceus)群体特征的影响,在(25±0.5)℃条件下对1、2、4和8尾青幼鱼组成的群体(N=12)进行视频拍摄和轨迹分析,得到游泳速度和空间分布特征数据,实验同时测定了不同群体大小对恐吓刺激的反应差异。结果显示:青幼鱼自发游泳速度多处于0—10 cm/s,不受群体大小的影响,但不同个体速度同步性随群体大小增加而显著下降;青幼鱼最近邻距离多数位于0—10 cm,且随着群体大小增加,最近邻距离和群体排列的极性均随群体数量上升而显著下降;青幼鱼群体中位置分布具有个体差异,且随着群体数量上升差异加剧;青幼鱼对恐吓刺激的反应率不受群体大小的影响,但群体内部不同个体对刺激的反应的一致性随群体大小上升有所下降。结果表明:青幼鱼具备集群性,在2—8个体范围内随群体大小上升凝聚力上升,协调性下降;群体特征的改变对恐吓刺激反应率没有显著影响,但协调性的下降导致反应一致性降低;青幼鱼群体中不同个体在集群活动中可能存在社会分工,且这种分工的作用在大群体大小上升表现更为明显。     

Social learning of fear and safety is determined by the demonstrator's racial group

Social learning offers an efficient route through which humans and other animals learn about potential dangers in the environment. Such learning inherently relies on the transmission of social information and should imply selectivity in what to learn from whom. Here, we conducted two observational learning experiments to assess how humans learn about danger and safety from members (‘demonstrators'') of an other social group than their own. We show that both fear and safety learning from a racial in-group demonstrator was more potent than learning from a racial out-group demonstrator.     

Trace Fear Conditioning in Mice

In this experiment we present a technique to measure learning and memory. In the trace fear conditioning protocol presented here there are five pairings between a neutral stimulus and an unconditioned stimulus. There is a 20 sec trace period that separates each conditioning trial. On the following day freezing is measured during presentation of the conditioned stimulus (CS) and trace period. On the third day there is an 8 min test to measure contextual memory. The representative results are from mice that were presented with the aversive unconditioned stimulus (shock) compared to mice that received the tone presentations without the unconditioned stimulus. Trace fear conditioning has been successfully used to detect subtle learning and memory deficits and enhancements in mice that are not found with other fear conditioning methods. This type of fear conditioning is believed to be dependent upon connections between the medial prefrontal cortex and the hippocampus. One current controversy is whether this method is believed to be amygdala-independent. Therefore, other fear conditioning testing is needed to examine amygdala-dependent learning and memory effects, such as through the delay fear conditioning.     

Relatedness and social organization of coypus in the Argentinean pampas

Behavioural and trapping studies of the social organization of coypus have suggested the occurrence of kin groups and a polygynous mating system. We used 16 microsatellite markers to analyse parentage and relatedness relationships in two populations (Jáuregui and Villa Ruiz) in the Argentinean Pampas. At Jáuregui, a dominant male monopolized most paternities, leading to a high variance in reproductive success between males and a high level of polygyny. At Villa Ruiz, variance in reproductive success was low among resident males and males were the fathers of zero to four offspring each. For females, no significant differences were found. Two different social groups in each study site were used to assess genetic relatedness within and between groups. These groups were neighbouring at Jáuregui but not at Villa Ruiz. At Villa Ruiz, coypus were significantly more related within than between groups, suggesting that behavioural groups were also genetic ones, and adult females were more related within than between groups, as should be expected for kin groups. This relationship was not found at Jáuregui. Our results provide support to previous studies based on behavioural and trapping data, which indicate that coypus form social groups and have a polygynous mating system. However, we found differences in social organization between the two populations. This is the first study to determine parentage and/or relatedness in coypus.     

牙科焦虑症治疗方法综述

牙科焦虑症主要是对疼痛的恐惧、对未知的恐惧、对机体受到伤害的恐惧等因素导致的焦虑症状。临床中80%的口腔疾病患者都对治疗心存恐惧,因此在很大程度上不能配合医生的治疗甚至逃避治疗。随着生活水平的不断提高,人们要求在舒适的心理环境中接受治疗,因此牙科焦虑症就成为口腔医护工作者必须面对的问题。治疗牙科焦虑症的方法主要分为行为学,药理学和有机放松法三个大类,在实际使用的过程当中往往是各种方法配合使用,而不是单一使用。随着人们研究的逐步深入,提出的具体治疗方法也越来越多,本文就牙科焦虑症目前所使用的治疗方法做详细的介绍及分类,帮助口腔医护工作人员理清治疗思路,为正确的诊断、干预和治疗牙科焦虑症提供治疗方法。     

Changes of movement behavior and HSP70 gene expression in the hemocytes of the mud crab (Scylla paramamosain) in response to acoustic stimulation

Offshore anthropogenic activities often produce high levels of noise below 1000 Hz, which can be serious threats to aquatic crustaceans based on the knowledge about their acoustic sensitive bandwidth. This study simulated noise with main frequency band similar to common underwater engineering noises, and examined its effects on movement behavior and physiological response, indicated by heat shock protein 70 (HSP70) gene expression, of the mud crab Scylla paramamosain. Experiments were conducted in the tanks, equipped with hydrophone, transducer, and video recording system, using juvenile S. paramamosain. Three acoustic stimulations with ascending levels were separately imposed on the animals. Results showed that the linear sweep with the sound power spectral density greater than 110 dB re 1μPa²/Hz in total bandwidth (100–1000 Hz), and 155 dB re 1μPa²/Hz within 600–800 Hz, could increase locomotor activities and HSP70 gene expression significantly.     

PHOTOPERIODIC REGULATION OF MT1 AND MT2 MELATONIN RECEPTOR EXPRESSION IN SPLEEN AND THYMUS OF A TROPICAL RODENT FUNAMBULUS PENNANTI DURING REPRODUCTIVELY ACTIVE AND INACTIVE PHASES

Photoperiodic regulation of melatonin receptor types on target tissues, such as lymphatic organs, has never been explored for any seasonal breeder. In the present study, we accessed the high affinity membrane melatonin receptors MT1 and MT2 expression dynamics in lymphoid organs (i.e., spleen and thymus) of a seasonally breeding rodent Funambulus pennanti during two major reproductive phases (i.e., active and inactive), when the internal hormonal (melatonin and gonadal steroid) as well as the ecological conditions were entirely different. Photoperiod regulates circulatory melatonin level; hence, we noted the effect of different photoperiodic regimes (long; 16L:8D and short; 10L:14D photoperiod) equivalent to summer and winter daylength on membrane melatonin receptor MT1 and MT2 expression in spleen and thymus. We have correlated the melatonin receptor expression with two major hormones varying seasonally (i.e., melatonin and testosterone) also being responsible for modulation of immunity of a seasonal breeder. Differential immunoreactivity of MT1 and MT2 receptor in spleen and thymus of F. pennanti suggests an involvement of both the receptor types in signal transduction of photoperiod for seasonal immunomodulation, because in the tropical zone, a slight difference (1:45–2?h) in daylength may change reproductive physiology and immunity of animals for adaptation. Our above suggestion receives strong support from the experiment of photoperiodic exposure on MT1 and MT2 expression at the translational level, where long daylength decreased the circulatory melatonin level and melatonin receptor expression in both lymphatic tissues. On the other hand, under short daylength, expression of MT1 and MT2 receptor increased in both spleen and thymus along with concomitant increase in circulatory melatonin level. Differential hormonal level of melatonin and gonadal hormones during reproductively active and inactive phase and its direct relation with melatonin receptor expression dynamics in lymphoid organs could be responsible for seasonal adjustment of immunity and reproduction. (Author correspondence: chaldar2001@yahoo.com)