高山倭蛙消化道结构初步观察

高山倭蛙食道粘膜上皮为复层柱状上皮,且固有膜中有丰富的复泡状腺;胃贲门部粘膜上皮无杯状细胞,PAS反应显示固有膜中有深红色颗粒分布,胃体中胃腺丰富;肠分为小肠、大肠、直肠3部分.小肠和直肠上皮中杯状细胞数量多.无尾类消化道结构与海拔高度无明显相关关系.     

Comparative Skin Histology of Frogs Reveals High-elevation Adaptation of the Tibetan Nanorana parkeri

Adaptations to extreme environmental conditions are intriguing. Animal skin, which directly interacts with external environment, plays diverse and important roles in adaptive evolution. The thin and bare skin of amphibians is sensitive to external environmental conditions and, thus, it facilitates investigations into adaptations for living in extreme environments. Herein, we compare the structures of skin in four anuran species living at elevations ranging from 100 m to 4500 m to assess phenotypic innovations in the skin of Nanorana parkeri, which lives at extremely high elevations. Analyses reveal similar basic skin structures, but N. parkeri differs from the other species by having more epidermal capillaries and granular glands, which correlate highly with responses to hypoxia and/or ultraviolet(UV) radiation. Further intraspecific comparisons from frogs taken at ～4500 m and ～2900 m reveal that all of the changes are fixed. Changes occurring only in the higher elevation population, such as possessing more skin pigments, may represent local adaptations to coldness and/or UV radiation. These results provide a morphological basis for understanding further the molecular adaptations of these frogs.     

The Expression Plasticity of Hypoxia Related Genes in High-Altitude and Plains Nanorana parkeri Populations

For species that have a broad geographic distribution, adaptive variation may be attributable to gene expression plasticity. Nanorana parkeri is an anuran endemic to the southern Tibetan Plateau where it has an extensive altitudinal range(2850 to 5100 m asl). Low oxygen concentration is one of the main environmental characteristics of the Tibetan Plateau. Hypoxia-inducible factor α subunits(HIF-1α and HIF-2α, encoded by Endothelial PAS domain protein 1(EPAS1)) and associated genes(e.g., vascular endothelial growth factor(VEGF) and Erythropoietin(EPO)) play crucial roles in maintaining oxygen homeostasis. In this study, we compared the expression of HIF-1A, VEGF, EPAS1 and EPO mRNA between two populations of N. parkeri: one population inhabiting the native high altitudes, and the second living in, and being acclimated to, the lower plains(70 m asl). The expression of HIF-1A, VEGF and EPAS1 mRNA in the high altitude population were significantly higher than in the acclimated population, whereas there was no significant difference for EPO between two groups. Our results indicated that gene expression plasticity may make significant contributions to local adaptation of species that have broad altitudinal distributions. In addition, we deepen our understanding of the adaptive potential of this species by evaluating the experiments in the scope of its evolutionary history.     

The Influence of Environmental Factors on the Behavior and Mortality Risk of Polypedates megacephalus Tadpoles

Since tadpoles change their behavior when facing adverse environmental conditions, observing tadpoles in a tank can help detect problems in their ma intena nce. Detecting such a bnormal behavior early, an amphibian breeder can react quickly, by changing the conditions. If quick and appropriate, such a reaction can save unnecessary deaths. The paper presents an experimental study on the behavior of tadpoles of Polypedates megacephalus in various adverse environmental conditions. In addition to a control 25-liter tank, 5-liter tanks with 10 tadpoles each were studied, each having various improper conditions. Observations included the degree of tank exploration by the tadpoles, their mortality, anomalies in swimming behavior, and eating behavior.     

Ecology of the Hybridogenetic Rana esculenta Complex: Differential Oxygen Requirements of Tadpoles

Because of intrinsic demographic load induced by hybridogenesis (infertility of homotypic hybrid matings), the maintenance of hybrid lineages supposes that they present better performances (heterosis) than their host species which allows them to coexist on a long-term basis. However, this necessity of high fitness can be relaxed if a relative niche partitioning occurs between the taxa, each of them differing in their ecological optima. In the waterfrog hybridogenetic complex (Rana esculenta complex), recent studies have revealed that hybrids show intermediate distribution between parental species across a gradient of river influence (that is related to a gradient of oxygen levels), and intermediate performances of their tadpoles with regard to oxygen availability (hypoxia). In investigating oxygen consumption rates, survival time in anoxia, and metabolite contents in the three forms of the complex, the present study confirms intermediate characteristics of hybrid tadpoles (R. esculenta) when compared to both parental lineages (R. lessonae and R. ridibunda). Whereas R. ridibunda tadpoles were the most sensitive to anoxia, R. lessonae tadpoles were the most tolerant. Because oxygen requirements of the hybrid proved to be intermediate, no heterosis was detected. These results confirm the hypothesis of the intermediate niche hypothesis to explain the coexistence of R. lessonae and R. esculenta and the success of the hybridogens.     

敌敌畏对多疣狭口蛙不同发育期蝌蚪的急性毒性影响

为了解农药对不同发育期蝌蚪的毒性,以多疣狭口蛙Kaloula verrucosa蝌蚪为对象,采用水生生物急性毒性试验方法,研究杀虫剂敌敌畏(DDVP)对25期、26期、35期和42期蝌蚪的急性毒性影响.结果表明,在水温19.5～22.0℃条件下,敌敌畏对各期蝌蚪96 h LC50分别为1.13、1.43、1.38和0.61 mg/L,各期蝌蚪对敌敌畏的敏感顺序为42期>25期>35期>26期.由此得出敌敌畏对25期、26期和35期蝌蚪属中等毒性,对42期蝌蚪则表现为高毒.因此建议农药施用应尽量避开蝌蚪的变态期进行.蛙类胚胎期(出膜后)随着发育对外界环境的耐受性增强,蝌蚪期随着发育对外界环境的敏感性增强.鉴于42期蝌蚪意外死亡率高的特点,认为不宜采用变态期蝌蚪进行急性毒性试验.     

DNA Barcodes and Species Distribution Models Evaluate Threats of Global Climate Changes to Genetic Diversity: A Case Study from Nanorana parkeri (Anura: Dicroglossidae)

Anthropogenic global climate changes are one of the greatest threats to biodiversity. Distribution modeling can predict the effects of climate changes and potentially their effects on genetic diversity. DNA barcoding quickly identifies patterns of genetic diversity. As a case study, we use DNA barcodes and distribution models to predict threats under climate changes in the frog Nanorana parkeri, which is endemic to the Qinghai-Tibetan Plateau. Barcoding identifies major lineages W and E. Lineage W has a single origin in a refugium and Lineage E derives from three refugia. All refugia locate in river valleys and each greatly contributes to the current level of intraspecific genetic diversity. Species distribution models suggest that global climate changes will greatly influence N. parkeri, especially in the level of genetic diversity, because two former refugia will fail to provide suitable habitat. Our pipeline provides a novel application of DNA barcoding and has important implications for the conservation of biodiversity in southern areas of the Qinghai-Tibetan Plateau.     

The Influence of Oxygen on the Production of Volatile Compounds by Dipodascus aggregates

The production of volatile compounds by Dipodascus aggregatus was studied in relation to the oxygen concentration in the medium. Oxygen concentration was determined with a Clark oxygen electrode and volatile compounds in the atmosphere above the culture by a gas chromatographic technique. Shake cultures of the fungus in its stationary phase of growth were very sensitive to a decrease in oxygen concentration in the presence of residual glucose. Anaerobic conditions induced production of volatile compounds that continued for many hours. The pattern of production of volatile compounds observed under conditions of low oxygen concentration during the stationary phase of growth differed from that obtained under aerobic conditions during the exponential phase of growth.     

倭蛙属(无尾目:蛙科)肩带研究

对倭蛙属（Nanorana）已知3种：高山倭蛙（Nanorana parkeri）、倭蛙（N. pleskei）和腹斑倭蛙（N. ventripunctata）的肩带作了连续切片后进行Masson染色,发现其上喙骨（epicoracoid）的融合与重叠的状况与虎纹蛙（Rana rugulosa）较相似,而与无尾目中其它物种已知的肩带形态存在较大的差异.倭蛙属和虎纹蛙等与已知肩带类型的蛙亚科其它的物种在系统进化中可能来源于不同的最近共同祖先.     

The Influence of Light and Oxygen on Nitrogenase Activity in the Lichen Stereocaulon paschale

Thalli of the lichen Slereocaulon paschale (L.) Fr. were prctreated in the light (light activated) or in the dark (dark starved). In short-time experiments with both light activated arid dark starved thalli, the nitrogenasc activity was higher in the light than in the dark, Light activated thalli had a very much higher rale of C₂H₂ reduction than dark starved thalli, both in the light and in the dark. The dark starved lhalli showed increasing nilrogenase activity when incubated in the light. Either light or oxygen was necessary for nitrogenase activity in light activated thalli. and up to about 10kPa oxygen they showed additive effects. Both in the light and in the dark the nitrogenase activity decreased when the oxygen partial pressure was lower than in normal air. The experimental data thus showed a short-term effect of light on nilrogenase activity by provision of ATP and reductant, and a long term effect probably by build up of reserves that were later utilized. Any immediate effect of photorespiration on nitrogenase activity could not be found in light activated thalli.     

Fine Structure of the Sporogonic Stages of Nosema parkeri

SYNOPSIS The fine structure of sporogonic stages of Nosema parkeri Krinsky, a microsporidan from the argasid tick, Ornithodoros parkeri Cooley, is described. Developmental changes in the spore coat and cytoplasmic organelles are discussed. As a sporoblast transforms into a spore, the organelles become more compact and the membranes surrounding them appear to become more taut. It is suggested that the polaroplast complex is involved in fluid transport during development of the spore. Organelles in the mature spore include 2 contiguous nuclei enveloped in a lattice containing ribosome-like particles, a polaroplast complex composed of laminar and saccular regions, and a coiled tubular polar filament attached to a polar sac. Sporogonic stages do not appear to have mitochondria, Golgi apparatus, or a posterior vacuole. The fine structure of the spore of N. parkeri is very similar to that of species of Nosema found in insects, crustaceans, and trematodes.     

杀虫双溶液对峨嵋林蛙(Rana omeimontis) 蝌蚪行为的影响

研究了峨嵋林蛙(Rana omeimontis)蝌蚪在杀虫双溶液中半致死浓度及其行为。利用寇氏法(Karber法)计算其96h内的半致死浓度为10．495mg/l,安全浓度为1．0495mg/l;运用方差分析检验了不同浓度中空间分布和活动性等行为的差异性。通过对空间分布型的拟合,可以得出：不论在实验组中还是在对照组中,蝌蚪在水族箱中的空间分布均为负二项分布,并且方差分析结果表明对照组和实验组中聚集度(负二项分布的参数k值)大小差异不显著,说明在此浓度范围内杀虫双对蝌蚪的微空间分布格局没有影响。而蝌蚪在杀虫双溶液中的活动性分析表明,0．25mg／l的杀虫双溶液对蝌蚪的活动性行为已经造成一定的影响,所以建议寻找安全浓度时,应该结合行为方面标的观察结果。