Effects of Abnormal Early Rearing Environments on Fear Memory in Adult Rats

为了探讨早期饲养环境对成年后大鼠条件化恐惧的影响,实验采用巴氏恐惧条件化的方法对不同饲养环境下的大鼠进行了行为检测.具体操作为:把断奶后的大鼠饲养在3个不同的人工控制的环境中(丰富环境、社群环境和贫瘠环境);8周后进行恐惧条件化训练和测试(指标为僵直百分比),以及检测不同饲养环境下的大鼠的体重、自发活动和足部电击敏感性.结果显示:与社群组相比,丰富组的大鼠条件化僵直水平明显增加,而贫瘠组的明显减少;丰富和贫瘠环境明显的影响了大鼠的体重;不同环境对自发活动和足部电击敏感性没有影响.这些结果说明幼年期的丰富环境能提高成年后大鼠的由声音诱发的条件化恐惧反应,而贫瘠环境则削弱了这种反应.

Diet and feeding behavior of Rhinopithecus bieti at Xiaochangdu, Tibet: Adaptations to a marginal environment

The diet and feeding ecology of a wild subpopulation of black-and-white snub-nosed monkeys (Rhinopithecus bieti) were studied at Xiaochangdu in Honglaxueshan Nature Reserve, Tibet. This region is climatologically harsher than any other inhabited by non-human primates. Black-and-white snub-nosed monkeys fed on 48 parts of 25 plant species, at least three species of lichens and seven species of invertebrates. The number of food items exploited varied markedly among seasons, with dietary diversity being greatest in spring and summer. In winter, black-and-white snub-nosed monkeys had to subsist on fallback foods such as dried grass and bark. Ubiquitous lichens formed a major dietary constituent throughout the year, contributing about 75% of feeding records. Even though lichens act as a staple, our findings signify that the monkeys at Xiaochangdu prefer feeding on foliage, which is higher in protein content than the former. We provide evidence that black-and-white snub-nosed monkeys are able to cope with an array of food items other than lichens and hence can be regarded as feeding generalists. We discuss the results with reference to previous studies on other subpopulations living in habitats that are floristically more diverse and offer more plant food items than the marginal habitat at Xiaochangdu.

THE RESPONSES OF Microcystis TO SEDIMENT ENVIRONMENTS AND THE ASSESSMENT FOR ITS OVERWINTERING - A SIMULATION STUDY IN A NOVEL DEVICE

A novel multi-cell device made of organic glass was designed to study morphological and physiological characteristics of Microcystis population trapped in simulated sediment conditions. Changes of colonial morphology and antioxidant activities of the population were observed and measured over the range of 31-day incubation. During the incubation, the antioxidant enzyme activities fluctuated significantly in sediment environments. The activities of catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (NIDA) reached the highest on the 11(th) day, 6(th) day and 6(th) day. respectively, and then dropped down remarkably in the following days. The ratios of Fv/Fm and the maximal electron transfer rate (ETRm) declined during the initial days (1 similar to 11(th) day), but rebounded on the 16(th) day, which were consistent with the variations of total protein. In the end of incubation. gas vacuoles were hard]), observed and the gelatinous sheath was partly disappeared in the population of Microcystis. Nevertheless, the remaining populations. upon transferred to culture medium, were able to grow though experiencing a longer lag phase of nine days. The results indicated that the sediment environments were able to cause negative effects on M. aeruginosa cells. The cells, however, responded to against the possible damage afterwards. It is thus proposed the acute responses in the population during the early stage of sedimentation could be of importance in aiding the long-term survivor of Microcystis and recruitment in lake sediments. The present study also demonstrated the utility of the device in simulating the sediment environments for further investigation.