黄姑鱼的恶性黑色素瘤

从我国南海海域捕获的黄姑鱼(Nibea albiflora)中发现15例恶性黑色素瘤(malignant melanoma)。本文较详细地介绍了有关这种肿瘤的病理解剖学、病理组织学和超微结构的观察结果。在国内外首次报道黄姑鱼的这种恶性肿瘤对肿瘤学有一定的研究价值。     

A preliminary study assessing risk to Tasmanian devils from poisoning for red foxes

The recent introduction of red foxes (Vulpes vulpes) to Australia's island state of Tasmania represents a major threat to native fauna. In response, the Tasmanian government has begun a fox eradication program using Foxoff®, a bait containing the poison sodium monofluoroacetate (commonly known as 1080). The bait is potentially attractive to native Tasmanian carnivores as well as to foxes. Of particular concern is the endangered Tasmanian devil (Sarcophilus harrisii), which is already at risk from an emergent infectious disease, devil facial tumor disease (DFTD). In both a captive and a field study using non-toxic Foxoff bait, we assessed bait palatability and possible effects of demographics, hunger level, bait age, and bait burial method on the likelihood of bait uptake by Tasmanian devils. Captive devils showed varying interest in the bait, but wild devils appeared to find it uniformly palatable. In the captive study, males and younger, captive-born animals were more likely to excavate and remove bait. Subterranean burial at 15 cm was the most effective deterrent to bait excavation; effectiveness decreased at shallower depths and with surface-level bait buried beneath soil mounds. Our findings suggest that the current fox-baiting campaign may negatively impact individual devils. More extensive study is necessary to assess potential risk at the population level. © 2011 The Wildlife Society.     

Understanding How the Complex Molecular Architecture of Mannan-degrading Hydrolases Contributes to Plant Cell Wall Degradation

Microbial degradation of plant cell walls is a central component of the carbon cycle and is of increasing importance in environmentally significant industries. Plant cell wall-degrading enzymes have a complex molecular architecture consisting of catalytic modules and, frequently, multiple non-catalytic carbohydrate binding modules (CBMs). It is currently unclear whether the specificities of the CBMs or the topology of the catalytic modules are the primary drivers for the specificity of these enzymes against plant cell walls. Here, we have evaluated the relationship between CBM specificity and their capacity to enhance the activity of GH5 and GH26 mannanases and CE2 esterases against intact plant cell walls. The data show that cellulose and mannan binding CBMs have the greatest impact on the removal of mannan from tobacco and Physcomitrella cell walls, respectively. Although the action of the GH5 mannanase was independent of the context of mannan in tobacco cell walls, a significant proportion of the polysaccharide was inaccessible to the GH26 enzyme. The recalcitrant mannan, however, was fully accessible to the GH26 mannanase appended to a cellulose binding CBM. Although CE2 esterases display similar specificities against acetylated substrates in vitro, only CjCE2C was active against acetylated mannan in Physcomitrella. Appending a mannan binding CBM27 to CjCE2C potentiated its activity against Physcomitrella walls, whereas a xylan binding CBM reduced the capacity of esterases to deacetylate xylan in tobacco walls. This work provides insight into the biological significance for the complex array of hydrolytic enzymes expressed by plant cell wall-degrading microorganisms.     

Nondestructive and continuous observation of nectar volume using time‐interval photography

To observe temporal changes in the nectar volume of Impatiens flowers, we modified and used an interval‐shooting camera with a special flash system. Former methods of measuring nectar volume inevitably necessitated destruction or damage of the floral parts. As a consequence, accurate continuous measurements of nectar volume under natural conditions have been difficult. While considering how to overcome this problem we noticed that when flowers were observed against transmitted light from the sun, a silhouette of nectar was visible inside the spur. To exploit this phenomenon, we attached a polymer optical fiber to the built‐in flash of a compact digital camera and bent the fiber towards the camera's lens to provide backlighting. We took interval images and estimated the nectar volume from the size of nectar silhouette. To our knowledge, this is the first reported method involving the use of time‐interval photography for measuring nectar volume in situ.     

基于光学仪器法测定谷地云冷杉林叶面积指数的季节变化

利用半球摄影法(DHP)和LAI-2000植物冠层分析仪两种光学仪器法(间接法)以及凋落物法(直接法),研究了小兴安岭谷地云冷杉林叶面积指数(LAI)的季节变化,并构建了不同季节直接法与间接法测定的LAI间的相关关系.结果表明: 在整个试验期间,DHP测定的LAI比直接法测定值低估40%～48%, LAI-2000植物冠层分析仪的低估范围为15%～26%;不同时期直接法与DHP和LAI-2000植物冠层分析仪测定的LAI均显著相关, 且均可合并为A、B、C 3类预测模型, 可以分别预测5和11月, 6、9和10月, 7和8月的LAI.本研究结果可为高效、准确地测定针叶林LAI的季节变化提供参考.     

用于海洋原位浮游生物探测的同轴数字全息显微技术研究

本文将数字全息与显微成像技术相结合,设计搭建了一套数字全息显微系统,用于对浮游生物进行光场获取。基于该系统获取的光场信息,通过在不同景深对图像进行再现,既可以获到单一浮游生物的清晰图像,也可以获得一定水体内浮游生物微粒在海水中的三维分布情况。通过实验测得系统分辨率可以达到7．8微米,景深可以达到10毫米,优于一般光学显微镜的技术指标。研究结果表明优势明显的数字全息显微系统是一种适合海洋原位探测的浮游生物研究的有效方法。基于数字同轴显微系统的水下仪器开发将是下一步工作的努力方向。     

Bacillus cereus Certhrax ADP-ribosylates Vinculin to Disrupt Focal Adhesion Complexes and Cell Adhesion

Bacillus cereus is often associated with mild to moderate gastroenteritis; however, some recent isolates cause inhalational anthrax-like diseases and death. These potential emerging human pathogens express multiple virulence factors. B. cereus strain G9241 expresses anthrax toxin, several polysaccharide capsules, and the novel ADP-ribosyltransferase, Certhrax. In this study, we show that Certhrax ADP-ribosylates Arg-433 of vinculin, a protein that coordinates actin cytoskeleton and extracellular matrix interactions. ADP-ribosylation of vinculin disrupted focal adhesion complexes and redistributed vinculin to the cytoplasm. Exogenous vinculin rescued these phenotypes. This provides a mechanism for strain G9241 to breach host barrier defenses and promote bacterial growth and spread. Certhrax is the first bacterial toxin to add a post-translational modification to vinculin to disrupt the actin cytoskeleton.     

Fifty‐seven years of composition change in the eastern boreal forest of Canada

Question: In the boreal forest of eastern Canada, how does forest vegetation change in the sustained absence of fire? Location: Eastern boreal forest in Quebec's North Shore region, Canada (49°30′–50°00′N; 67°30′–68°35′W). Methods: Aerial photos from three different periods (1930, 1965 and 1987) were used to characterize changes in vegetation composition in 23 scenes of 200 ha. Time since fire, presence of secondary disturbances and data on soil and topographic variables were obtained. Ordination and clustering techniques were used to define compositional trajectories of change over the 57‐yr period. These trajectories were further grouped into pathways based on compositional changes, time since fire and preferential deposit‐drainage types. Results: Among the 26 compositional trajectories, three successional pathways were distinguished. Two start post‐fire succession with a dominance of intolerant hardwood. In one of these, this is followed by an increase in Abies balsamea, while in the second the importance of Picea mariana increases with time. In the third pathway P. mariana is an important component from the outset. In this pathway, we observed modest fluctuation in the relative dominance of P. mariana and A. balsamea and variation in stand structure. Conclusion: The boreal forest vegetation of Eastern Canada is diverse and dynamic even in the absence of fire, notably under the influence of partial disturbances. Such disturbances can be associated with changes in composition or stand structure. The development of management strategies aimed at maintaining stand diversity by emulating a broader variety of partial and secondary disturbances should be encouraged.     

云南干旱河谷150年来的植被变化研究及其对生态恢复的意义（英文）

 在中国西南有许多关于过去环境及其变化原因的观点,但这些观点缺乏直接证据的支持,这在关于西南干 旱河谷生态系统方面最为典型,而且目前干旱河谷地区的生物多样性保护和生态恢复计划主要都是基于这 些主观的认识而不是科学的理解。该文的目的是通过对干旱河谷环境变化的描述及其诠释,提供干旱河谷 的一个历史面貌,用以验证是否支持当前对于干旱河谷环境变化的认识和理解,该文研究的干旱河谷范围 包括滇西北及其临近的四川和西藏。28份1868～1949年间刊行的出版物中有关研究地区干旱河谷植被的历 史资料和56幅清晰反映干旱河谷植被范围和状况的照片形成研究这种变化的历史基础,通过与2001～2005 年间相同地区和范围的植被现状以及56幅与上述照片取景完全相同的重复照片的比较,研究了干旱河谷植 被的变化。研究结果发现,在过去约150年间,研究地区的干旱河谷植被范围并没有显著的变化,在垂直 方向没有向较高海拔扩展;耕地面积减少;滑坡主要是由当地本身的地质不稳定性和基础设施建设活动引 起的。1868～2005年间文献资料和重复景观照片的对比研究,并不支持国内外许多有关干旱河谷环境退化 的看法和观点以及以造林为主的干旱河谷生态恢复策略。