Short- and Long-term Effects of High Temperatures (47–49 °C) on Tobacco Leaves. I. Photosynthesis

Detached Nicotiana rustica leaves were exposed for 2 minutes to temperatures in the range 36° to 51°C. Above 45°C, ¹⁴CO₂ fixation was reduced by half as compared with controls. The fall in ¹⁴CO₂ fixation continued for 2 1/2 h. Recovery was completed 45 h after the treatment. Above 45°C there was an increase in the labeled cationic and anionic fractions and a decrease in the neutral fractions, both increase and decrease being associated with the impaired CO₂ fixation. However, these changes in products were also demonstrated when leaves were exposed to the high temperature after labeling.     

On the evolutionary and ontogenetic origins of tool‐oriented behaviour in New Caledonian crows (Corvus moneduloides)

New Caledonian crows (Corvus moneduloides) are prolific tool users in captivity and in the wild, and have an inherited predisposition to express tool‐oriented behaviours. To further understand the evolution and development of tool use, we compared the development of object manipulation in New Caledonian crows and common ravens (Corvus corax), which do not routinely use tools. We found striking qualitative similarities in the ontogeny of tool‐oriented behaviour in New Caledonian crows and food‐caching behaviour in ravens. Given that the common ancestor of New Caledonian crows and ravens was almost certainly a caching species, we therefore propose that the basic action patterns for tool use in New Caledonian crows may have their evolutionary origins in caching behaviour. Noncombinatorial object manipulations had similar frequencies in the two species. However, frequencies of object combinations that are precursors to functional behaviour increased in New Caledonian crows and decreased in ravens throughout the study period, ending 6 weeks post‐fledging. These quantitative observations are consistent with the hypothesis that New Caledonian crows develop tool‐oriented behaviour because of an increased motivation to perform object combinations that facilitate the necessary learning. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 870–877.     

树鼩CXCR4 cDNA的克隆和序列分析

目的　获得树CXCR4的cDNA序列 ,探讨其是否可以支持HIV_1病毒和细胞的结合。方法　设计相应的引物 ,用RT_PCR ,基因克隆 ,DNA序列分析技术。结果　获得了全长为 10 59bp树CXCR4(tsCXCR4)基因的cDNA。发现其核苷酸序列与人的CXCR4(hCXCR4)基因的cDNA有 92 8%的相似性 ,由此推导出的氨基酸序列有 96 9%相似性。与hCXCR4功能相关的关键位点完全相同 ,tsCXCR4的N端第 7和 12位点为酪氨酸 ,第 14、15和3 2位点为谷氨酸 ,胞外环第 183 ,188为精氨酸 ,第 193、2 62位点以及跨膜区 97位点为天冬氨酸。结论　树的CX CR4很可能会作为HIV_1的辅助受体     

细胞生物学教学中的反思型教师教育

在分析了反思型教师教育兴起的背景后,作者在师范生《细胞生物学及实验》课程教学中,进行了两方面的反思性教学尝试：一方面实施对教学环节全过程的反思,另一方面是让学生参与教学实践。结果表明对师范生实施反思性教学,可以提高学生的反思能力,有利于师范生形成反思意识,养成初步的反思习惯,学生的反思能力显著提高。     

The Mediterranean Sea as a ‘cul‐de‐sac’ for endemic fishes facing climate change

The Mediterranean Sea is a hotspot of biodiversity, and climate warming is expected to have a significant influence on its endemic fish species. However, no previous studies have predicted whether fish species will experience geographic range extensions or contractions as a consequence of warming. Here, we projected the potential future climatic niches of 75 Mediterranean Sea endemic fish species based on a global warming scenario implemented with the Mediterranean model OPAMED8 and a multimodel inference, which included uncertainty. By 2070–2099, the average surface temperature of the Mediterranean Sea was projected to warm by 3.1 °C. Projections for 2041–2060 are that 25 species would qualify for the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List, and six species would become extinct. By 2070–2099, 45 species were expected to qualify for the IUCN Red List whereas 14 were expected to become extinct. By the middle of the 21st century, the coldest areas of the Mediterranean Sea (Adriatic Sea and Gulf of Lion) would act as a refuge for cold‐water species, but by the end of the century, those areas were projected to become a ‘cul‐de‐sac’ that would drive those species towards extinction. In addition, the range size of endemic species was projected to undergo extensive fragmentation, which is a potentially aggravating factor. Since a majority of endemic fishes are specialists, regarding substratum and diet, we may expect a reduced ability to track projected climatic niches. As a whole, 25% of the Mediterranean Sea continental shelf was predicted to experience a total modification of endemic species assemblages by the end of the 21st century. This expected turnover rate could be mitigated by marine protected areas or accelerated by fishing pressure or competition from exotic fishes. It remains a challenge to predict how these assemblage modifications might affect ecosystem function.