Multiple mate choice criteria and the importance of age for male mating success in the microhylid frog, Cophixalus ornatus

We examined multiple mate choice criteria in Cophixalus ornatus, a terrestrial breeding, microhylid frog. Mate choice consisted of three stages: mate attraction (male calling), courtship (male behavior between the call site and the nest), and nest site selection by the female. For male C. ornatus, the possession of a call with low dominant frequency relative to calling neighbors increased the probability that they would attract females. Dominant frequency was negatively correlated with age independent of male mass and snout vent length. When escorting the female from the call site to their nest, males traveled along more convoluted paths than when returning to the nest alone. The convolution of the path was, therefore, considered an aspect of courtship. Females released eggs into nests with structural characteristics typical of nests constructed by older males. Thus, females increased their chances of locating an acceptable nest by preferentially approaching males with lower dominant frequencies. This study is the first to demonstrate that age, independent of mass or snout-vent length, can influence call characteristics in anurans, and it is also the first to demonstrate the importance of male age to female mate choice in an amphibian.     

Rubisco of Dunaliella tertiolecta is redistributed between the pyrenoid and the stroma as a light /shade response

 We used an immunofluorescence technique to investigate the effects of varying light regimes on ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) in individual cells of the chlorophyte Dunaliella tertiolecta Butcher. These studies were carried out between September 1995 and February 1996. The population was heterogeneous with respect to Rubisco localization in the pyrenoid, i.e. in some cells Rubisco staining was highly concentrated in the pyrenoid while in others it was evenly distributed throughout the chloroplast stroma. When light intensity was varied sevenfold, the fraction of the cell population that displayed distinct Rubisco staining in the pyrenoid (PR-index) was correlated with light intensity, although the average Rubisco abundance per cell or per total cellular protein appeared fairly constant. In darkness, or when treated with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU), the PR-index decreased markedly during the first 4 and 3 h, respectively, and then remained at low levels, while the cell division cycle progression remained unaffected. We conclude that D. tertiolecta probably possesses an adaptive mechanism, i.e. the redistribution of Rubisco between the pyrenoid (probably the active site of Rubisco activation and CO₂ fixation) and the stroma (probably a reservoir of deactivated Rubisco that is readily available for transport to the pyrenoid and activation), to respond to variations in irradiance or photosynthetic inhibition. Our results also suggest that this mechanism is insensitive to slight variations in growth irradiance and to seasonal changes in photoperiod and temperature. Received: 19 August 1996 / Accepted: 12 September 1996     

农村水环境保护与经济可持续发展

我国的生态环境问题 ,如水土流失、草场退化、沙漠化、盐渍化等问题 ,归根到底还是农村水环境问题。本文分析了农村水环境保护、高效利用水资源的紧迫性 ,以及影响农村生态系统可持续性的因素和保护、改善农村水环境的主要措施 ;认为加强农村水环境保护及其持续发展能力的建设是我国整个社会特别是农村经济可持续发展的基本保障     

Influence of hydroxypropylcyclodextrins on the toxicity of mixtures

We studied the influence of hydroxypropylcyclodextrins (HPCDs) on the toxicity of some mixtures. Using the Photobacterium phosphoreum toxicity test, the joint toxicological effect for Mixture I (containing p-nitrobenzaldehyde and 1-nitronaphthalene) and Mixture II (containing p-nitrobenzaldehyde and malononitrile) were determined in water and in aqueous solutions of HPCDs. The results indicate that, although the toxicological joint effect for Mixture I (simple addition) differs from that of Mixture II (synergism), alpha- and beta-HPCD can significantly reduce the toxicity of the test compounds, whereas gamma-HPCD has only a slight effect. Explanations for these observations are given that invoke the molecular structure of the individual chemicals as well as the structures of HPCDs. This provides information to assist the application of HPCDs in remediation of environmental pollution.     

贵州省西部环境灾害与防治

本文分析了贵州西部环境灾害的形成原因，它既受自然因素的影响，也受人类活动的影响。并提出了防治贵州西部环境灾害的基本措施。     

重型柴油车车载排放实测与加载影响研究

采用车载排放测试仪,对2辆重型柴油卡车在空载和加载条件下进行实际道路车载排放测试.通过分析获得了油耗与排放速率的速度-加速度及其工况点的分布,发现高油耗与高排放工况点主要集中在高速加速区域,加载时油耗与排放高值随工况点分布更广;车辆在(30±2.5)km·h^-1等速及加速行驶时受加载影响最大,此时加载油耗与排放约是空载的1.6～3.2倍左右;由实测结果发现,卡车Ⅰ和卡车Ⅱ加载时油耗及CO、HC、NO_x排放因子分别是空载的1.6倍、3.5倍、1.1倍、1.5倍以及1.2倍、1.0倍、0.9倍和1.5倍,加载对油耗与NO_x排放影响最为明显,对HC影响最小,CO影响取决于车辆保养水平;卡车Ⅱ较卡车Ⅰ车型更大,发动机功率更高,相同荷载时受加载影响较小,说明重型车在发动机负荷可承受的范围内合理装载,有助于避免油耗与排放恶化,提高燃油经济性和排放水平.