Biochemistry of frog ribonucleases

Frogs have unique pyrimidine base-specific RNases, with structures similar to those of turtle, iguana and chicken RNases. Among the four frog RNases discussed here, three from Rana pipiens, R. catesbeiana and R. japonica oocyte cells show anti-tumour activity, and the latter two show lectin activity towards sialic acid-rich glycoproteins. In this review, (i) we compare their unique primary structures with respect to the locations of their disulphide bridges, three-dimensional structure, base specificity and heat stability as compared with RNase A, and (ii) we summarize current knowledge about the mode of action of lectin and the antitumour activities of the three frog RNases.     

The tuning of moth ears

Summary The simple ears of months have responded evolutionarily to the varied levels of selection pressure exerted upon them by insectivorous bats. While frequency-matched (syntonic) bats exert the primary pressure that determines where a sypatric moth's best frequency (BF) lies, there are bats that echolocate in mismatched (allotonic) bandwidths forming selection pressures strong enough to warrant increased secondary sensitivity at these frequencies. It is unknown what neural mechanism is used by these insects to broaden their audiograms but for some neotropical moths, external hearing aids provide a mechanical means of obtaining this sensitivity. Recent studies have uncovered social uses for auditory systems in certain moths and these requirements may provide additional selection pressure. Auditory conditions exist in certain moths that should provide a means to study the evolution of this sensory system from its mechanoreceptor origins to its degeneration in the absence of bat predation.     

Reproductive phenology and pre‐dispersal seed‐feeding in Protium tovarense (Burseraceae), with a description of the first known phytophagous “Bracon” species (Hymenoptera: Braconidae: Braconinae)

The reproductive phenology of the cloud forest tree Protium tovarense (Burseraceae) is analysed for one population in northern Venezuela. Reproductive phenophases were monitored using both long‐term(21 years) and detailed short‐term (4 years) surveys of flower and fruit set. The reproductive phenology of this tree varies, with periods in which the species behaves as a supra‐annual reproducer, and other periods in which it reproduces annually, at the end of the rainy season. Marked spatial variation in reproductive condition was also observed, with subpopulations separated by less than 2 km showing contrasting phenological stages. Larval infestation of seeds by a braconid wasp was observed for a period of 1 year and is described. This wasp, the first obligately phytophagous species of Braconinae, is described as Bracon phytophagus Quicke sp. n. Percentage fruit infestation by this wasp was relatively high (50–60%) during the entire period (～10 months) of fruit development. The larval stages are described and illustrated, and compared with those of other phytophagous Ichneumonoidea. DNA sequencing of wasp colour variants provided no indication that multiple species were involved. Two related braconine species described in the genus Iphiaulax are transferred to Bracon, hence, B. flavipalpisimus replacement name (Szépligeti) ( = Iphiaulax flavipalpis Szépligeti, 1901 Szépligeti, G v. 1901. Tropische Cenocoeliden und Braconidae aus der Sammlung des Ungarischens National‐Museums.. Természetrajzi Füzetek, 24: 353–402.  [Google Scholar] not B. flavipalpis Thomson, 1892) and B. glabrescens (Szépligeti) n. comb. ( = Iphiaulax glabrescens Szépligeti, 1901 Szépligeti, G v. 1901. Tropische Cenocoeliden und Braconidae aus der Sammlung des Ungarischens National‐Museums.. Természetrajzi Füzetek, 24: 353–402.  [Google Scholar]). Evolutionary routes to phytophagy in braconid wasps and hypothetical scenarios in which this plant–seed predator interaction can be maintained are discussed.     

诏安,永泰,建宁两栖动物的调查及区系比较

本文报道闽南地区诏安县、闽中地区永泰县和闽北地区建宁县的两栖动物种类及其所从属的动物区系。已知３县的两栖类共有３６种，以华中区的种类沼势，华南区种类仅见于诏安。古北界的种类，建宁２种，永泰１种，诏安缺如，３县的动物区系与丁汉波等的划分基本相符。     

大眼隐翅虫对萝卜蚜捕食功能反应与寻找效应研究

在室内条件下，对大眼隐翅虫Stenus(Stenus，s．str．)sp．1成虫对萝卜蚜Lipaphis erysimi(Kaltenbach)的捕食作用及寻找效应进行了定量研究，结果表明大眼隐翅虫对萝卜蚜的功能反应符合Holling Ⅱ型模型，理论方程为Na=0．7937N／(1 0．1582N)，日最大捕食量为5.018头．大眼隐翅虫寻找效应随自身密度增加而降低，其数学模型为α=6．0131 P^-0.6254，其捕食作用与个体间相互干扰作用关系用Hasseu模型拟合为E=0．2530 P^-0.1468．     

茂兰自然保护区药用两栖动物资源

介绍了茂兰自然保护区药用两栖动物的种类及其用途,经整理,茂兰保护区药用两栖动物隶属于5科6属14种。属于国家Ⅱ级重点保护野生动物2种;国家重点保护野生药材1种;国家保护的有益的或者有重要经济、科学研究价值的陆生野生动物11种。     

广西玉林市挂榜山两栖动物初步调查研究

调查研究了广西玉林市挂榜山及其周边地区的两栖动物,共采集鉴定的两栖动物有155只,共计21种,隶属一目、5科、15属,占广西区种类76种的27.63%.主要区系成分为东洋界的华中一华南区种,共10种,占挂榜山总种数的47.61%,但以华南区为主要成分.挂榜山的两栖类物种多样性系故(H′)为1.08373,均匀度指数(J)为0.81963.     

亚致死剂量百草枯对七星瓢虫捕食及限域搜索行为的影响

 采用室内生物测定方法对七星瓢虫在亚致死剂量百草枯作用下的捕食和限域搜索行为进行了测定.毒力实验研究结果表明,田间常用百草枯体积比(20 mL/L)低于七星瓢虫成虫的LC₅₀,对七星瓢虫幼虫的杀伤作用死亡率为95.7%.捕食速率测定结果显示,LC20剂量的百草枯会对七星瓢虫尤其是其幼虫的捕食速率产生显著影响,24 h七星瓢虫幼虫、雌成虫、雄成虫的捕食速率分别下降了31.32%,23.47%和25.60%.此外,百草枯对七星瓢虫的限域搜索行为也产生了显著影响,百草枯处理后七星瓢虫搜索速率降低,搜索范围缩小.     

高阶作用对集团内捕食系统物种共存的影响

建立了常微分方程组模型,在集团内捕食系统中,分别考察种内高阶相互作用、种间高阶相互作用、密度调节及三者融合作用对种群密度产生的影响.MATLAB数值模拟结果表明,种内高阶相互作用、种间高阶相互作用均能够促进食饵和捕食者之间的共存,影响强度与密度调节相似,但是作用机制不同.     

全氟辛磺酸对于爪蟾的甲状腺激素干扰效应

运用两栖类变态实验(AMA)研究了全氟辛磺酸(PFOS)对于非洲爪蟾(Xenopus laevis)蝌蚪的生长、变态和甲状腺组织结构的影响.结果显示,与对照组相比,7d后,10,50和250μg.L-1PFOS暴露组蝌蚪的后肢长分别减小了17%,11%和18%,蝌蚪的发育延缓了1~2个阶段;19d后,10,50和250μg.L-1PFOS组蝌蚪的体重分别增加了17%,10%和20%,体长分别增加了5%,4%和6%,而10μg.L-1和250μg.L-1PFOS组蝌蚪的后肢长分别减小了12%和13%;暴露组甲状腺组织结构出现滤泡数目减少、上皮细胞增生、胶质减少甚至滤泡溶通等现象.结论是,在本实验浓度下,PFOS对于非洲爪蟾的蝌蚪生长有促进作用,对于变态发育过程却有抑制作用.参照AMA的方法,可以判断PFOS为抗甲状腺激素干扰物.