Species co‐occurrence patterns and dietary resource competition in primates

Diamond (Assembly of species communities. In: Cody ML, Diamond JM, editors. Ecology and evolution of communities. Cambridge: Belknap. p 342–444 ( 1975 )) argued that interspecific competition between species occupying similar niches results in a nonrandom pattern of species distributions. In particular, some species pairs may never be found in the same community due to competitive exclusion. Rigorous analytical methods have been developed to investigate the possible role that interspecific competition has on the evolution of communities. Many studies that have implemented these methods have shown support for Diamond's assembly rules, yet there are numerous exceptions. We build on this previous research by examining the co‐occurrence patterns of primate species in 109 communities from across the world. We used EcoSim to calculate a checkerboard (C) score for each region. The C score provides a measure of the proportion of species pairs that do not co‐occur in a set of communities. High C scores indicate that species are nonrandomly distributed throughout a region, and interspecific competition may be driving patterns of competitive exclusion. We conducted two sets of analyses. One included all primate species per region, and the second analysis assigned each species to one of four dietary guilds: frugivores, folivores, insectivores, and frugivore‐insectivores. Using all species per region, we found significantly high C scores in 9 of 10 regions examined. For frugivores, we found significantly high‐C scores in more than 50% of regions. In contrast, only 23% of regions exhibited significantly high‐C scores for folivores. Our results suggest that communities are nonrandomly structured and may be the result of greater levels of interspecific competition between frugivores compared to folivores. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.     

Mountain cheese factory wastewater treatment with the use of a hybrid constructed wetland

This paper describes the activity period of an experimental hybrid wetland system placed in a cold climate region. The aim is to determine the efficiency of the system in reducing TSS, BOD₅, COD and other pollutants. The constructed wetland consists of a fat-removal unit and a basin for the storage and the distribution of the wastewater which precedes three phytoremediation beds: the first two are parallel and they work as submerged vertical flow wetland with gravel medium for an area of 180 m²; the last is a submerged horizontal flow wetland with sand medium and an area of 360 m². The CW was designed to process a total estimated BOD₅ loading rate of about 24 g m⁻² d⁻¹, which was less than half of the average actual loading rate. The wastewater treatment did not meet the required Italian law outflow limits, most likely due to BOD₅ overloading.     

91例主动脉夹层动脉瘤的临床治疗体会

目的:依据临床经验,熟练运用开放手术、腔内修复术及杂交手术方法治疗各类主动脉夹层动脉瘤。方法:收集2009年7月~2013年1月在我院手术治疗的主动脉夹层动脉瘤患者共91例,StanfordB型夹层动脉瘤36例(其中21例降主动脉瘤、9例腹主动脉及双髂动脉瘤行腔内覆膜支架隔绝术,6例行腹主动脉人工血管置换术),StanfordA型夹层动脉瘤55例(其中单纯Sun,s手术12例伴Bentall术6例,Bentall术伴部分主动脉弓人工血管置换36例,1例行Ⅱ型的主干与分支动脉人工血管转流+介入腔内隔绝降主动脉及左半弓杂交术),分别以不同的手术方法给予治疗。结果:顺利治愈出院85例,死亡6例,4例因全弓置换术后出现难以控制的大出血、肠坏死、肾功能不全、少尿等并发症而死亡,2例死于Bentall术后严重多功能脏器急性衰竭,1例杂交手术术后出现高血压伴神经系统并发症,1例伴肺部感染及低心排综合征,给予对症治疗后效果不佳,有2例出现肾功能不全,经过透析治愈。腔内修复术后有神经系统的并发症2例,下肢的功能障碍2例,少量内漏4例,以上并发症均经对症治疗后痊愈。术后随访76例,时间3~12个月,除2例于术后第9个月死亡、1例因脑梗塞、脑血管意外等与手术无关的疾病而死亡,2例因吻合口动脉瘤或动脉瘤破裂大出血死亡外,余患者生活状态良好,心功能在I~Ⅱ级。结论:根据主动脉瘤疾病的临床特点和定位诊断,合理选择和运用治疗方法使手术操作变得更为迅速、安全和方便,同时能够取得良好的临床治疗效果。     

HOW COMMON IS HOMOPLOID HYBRID SPECIATION?

Hybridization has long been considered a process that prevents divergence between species. In contrast to this historical view, an increasing number of empirical studies claim to show evidence for hybrid speciation without a ploidy change. However, the importance of hybridization as a route to speciation is poorly understood, and many claims have been made with insufficient evidence that hybridization played a role in the speciation process. We propose criteria to determine the strength of evidence for homoploid hybrid speciation. Based on an evaluation of the literature using this framework, we conclude that although hybridization appears to be common, evidence for an important role of hybridization in homoploid speciation is more circumscribed.     

Assortative mating across a hybrid zone in Chorthippus parallelus (Orthoptera: Acrididae)

Two subspecies of the grasshopper Chorthippus parallelus meet and form a hybrid zone in the Pyrenees. Both strong hybrid dysfunction and a behavioural difference occur, which would seem to make the zone a suitable candidate for speciation by reinforcement. One of the classic ways of looking for this is to test for increased levels of assortative mating between populations from close to the region of contact. Here we show that, with virgin insects, such assortment decreases as one approaches the centre of the zone in C. parallelus. The pattern is different upon remating, with non-virgins showing a pattern more like that predicted by reinforcement. Overall there is little evidence for reinforcement. We argue that other tests of the model may be more appropriate for stable hybrid zones.     

玉米细胞质雄性不育及其育性恢复基因的研究进展

玉米是杂种优势利用最成功的作物之一,采用细胞质雄性不育(CMS)进行玉米杂交种生产已成为杂种优势利用的有力工具。CMS是由于细胞质和细胞核的基因表达产物的不协调而产生的不育性,可被核基因组中的恢复基因恢复。根据育性恢复专效性,玉米CMS材料主要分为T、C和S三种类型。综述了这三种类型不育及其恢复基因的研究进展,分析了在不育化制种中的应用情况。     

A novel pollen-specific α-tubulin in sunflower: structure and characterization

We describe here a new -tubulin isoform from sunflower we named -tubulin. -tubulin is the most divergent higher-plant -tubulin described so far, having an unusual deletion in the H1/B2 loop and a glutamine-rich C-terminus. We constructed a three-dimensional model and discuss its implications. Using specific antibodies, we show that -tubulin expression is restricted to the male gametophyte. -tubulin mRNA represents 90% of -tubulin mRNA and a small percentage of total pollen mRNA. Among the plants tested, -tubulin was only detected in sunflower and in Cosmos. Since both plants are Asteraceae, we propose that -tubulin is specific to this family. Our results suggest that -tubulin can inhibit tubulin assembly in pollen. This hypothesis is reinforced by the fact that -tubulin is found in a complex with -tubulin in mature sunflower pollen.     

The FliS chaperone selectively binds the disordered flagellin C-terminal D0 domain central to polymerisation

Assembly of each Salmonella typhimurium flagellum filament requires export and polymerisation of ca. 30000 flagellin (FliC) subunits. This is facilitated by the cytosolic chaperone FliS, which binds to the 494 residue FliC and inhibits its polymerisation. Yeast two-hybrid assays, co-purification and affinity blotting showed that FliS binds specifically to the C-terminal 40 amino acid component of the disordered D0 domain central to polymerisation. Without FliS binding, the C-terminus is degraded. Our data provide further support for the view that FliS is a domain-specific bodyguard preventing premature monomer interaction.