高原低氧对机体无氧代谢阈值的影响

为了探讨高原低氧对机体无氧代谢阈值(AT)的影响,本研究采用Wasserman无创性方法,分别测定了11名新兵在平原(四川淮口,海拔500m)和经空运进驻高原 (西藏错那,海拔4370m)后的第3、5、7和14天的AT。结果表明:新兵进驻高原后AT由平原的813.6±147.4kg·m/min降低到395.5±194.5 kg·m/min(P<0.01);高原低氧引起AT的降低幅度与受试者平原AT的高低呈正相关(r=0.933,P<0.01);进驻高原后第3、5、7天AT维持在较低水平,随后呈上升趋势。但移居高原1年战士的AT仍低于平原水平(P<0.05)。提示,高原低氧能够显著地降低机体的AT,并且AT越高的个体进驻高原后受低氧环境的影响程度越大。     

白翅叶蝉Empoasca subrufa Melichar的研究

白翅叶蝉是福建省水稻的重要害虫,苗期受害严重者,整片稻苗苍白,甚至枯死;早稻孕穗、抽穗期常大量发生为害,影响谷粒饱满度,造成减产。福州和闽侯地区一年发生4代,部分5代。成虫越冬。冬季日平均温度达11℃以上时仍能取食为害。春季成虫侵入稻田,4月下旬前后大量产卵,5月中旬虫数激增,5月下旬或6月初达到高峰。早稻收割时由于农事活动引致若虫大量死亡。晚稻田于8、9月虫数较多,但危害不如早稻严重。10月中旬以后成虫逐渐离开稻田,迁往越冬场所。 寄主植物幼嫩茂密和较大湿度的小生境有利于白翅叶蝉的发育繁殖。大发生的气候因子主要是春季多雨。适宜的温湿度范围为温度20—25℃,相对湿度85—90%。 DDT单独使用或DDT与666混用防治白翅叶蝉都能收到满意的效果。早稻秧田宜在播种后两周施药防治;本田于5月中旬虫口密度开始增长之际施药,亦能抑制为害。冬季小麦出土以前清除田边杂草,也是一项有效的防治措施     

Functional diversity decreases with temperature in high elevation ant fauna

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Hepatopancreas and ovary are sites of vitellogenin synthesis as determined from partial cDNA encoding of vitellogenin in the marine shrimp,Penaeus vannamei

Summary

The site of yolk protein synthesis in crustaceans has long been a subject of controversy. A portion of the vitellogenin gene structure was reported recently in a freshwater giant prawn (Macrobrachium rosenbergii) and black tiger shrimp (Penaeus monodori), in which the hepatopancreas was confirmed to be the extraovarian site of vitellogenin synthesis. The ovary is also frequently reported to be the site of yolk protein synthesis in penaeid shrimp. The same PCR product was obtained using cDNA from the hepatopancreas or the ovary as a template. The deduced amino acid sequence of Vg in P. vannamei showed high identities of 57% and 78% with those from M. rosenbergii and P. monodon, respectively. The same location of the intron in the sequenced region of genomic DNA was also found between these three species. We therefore concluded that the hepatopancreas and ovary are sites of vitellogenin synthesis in P. vannamei. The partial structure of the vitellogenin gene is further presented.     

Mass mortality of an asteriid starfish (Forcipulatida,Asteroidea, Echinodermata) from the late Maastrichtian (Late Cretaceous) of Morocco

Abstract: A mass occurrence, numbering tens of thousands of individuals in a single lens, belonging to a single species of asteroid, is described from the late Maastrichtian (Late Cetaceous) of Morocco. The lens of partially silicified asteroidal limestone is made up largely of fully articulated specimens of similar size and probably represents the mass mortality of a single recruitment. By comparison with mass strandings of the present‐day species Asterias rubens (Linnaeus), it can be inferred that a feeding swarm of individuals was swept into a submarine channel by either a storm or an exceptionally strong tidal current, and permanently buried. The genus and species are herein described as Cretasterias reticulatus gen. et sp. nov. The exceptional preservation of the material enables the identification of wreath organs (clusters of crossed pedicellariae set in a dermal pad around spines) for the first time in the fossil record. Comparison between extant Asteriidae, putative fossil asteriids and C. reticulatus provides ambiguous evidence of its affinities; it appears to display a combination of plesiomorphic and derived characters. It is shown that all Mesozoic forcipulatid asteroids described so far share a very simple arm construction (single row of adradial ossicles) unknown in adult extant Forcipulatida.     

Characterization and the broad cross‐species applicability of 20 anonymous nuclear loci isolated from the Taiwan Hwamei (Garrulax taewanus)

We isolated 20 anonymous nuclear loci (8556 bp in total) from the Taiwan Hwamei (Garrulax taewanus), an endemic songbird of Taiwan. A panel of nine to 15 individuals with unknown relationship was used to characterize polymorphism of these loci. We identified 46 single nucleotide polymorphic sites (SNPs) in 15 polymorphic loci. Frequency of SNPs was one per every 186 bp in average. Nucleotide diversity, θ, ranged from 0.00054 to 0.00371 per locus. We also tested cross‐species applicability of these loci on 17 species from eight different passerine families. All 20 loci could be successfully amplified (ranged from one to 16 species, mean = 7.9 species).     

Leafminers help us understand leaf hydraulic design

Leaf hydraulics of Aesculus hippocastanum L. were measured over the growing season and during extensive leaf mining by the larvae of an invasive moth (Cameraria ohridella Deschka et Dimic) that specifically destroy the palisade tissue. Leaves showed seasonal changes in hydraulic resistance (R_lamina) which were related to ontogeny. After leaf expansion was complete, the hydraulic resistance of leaves and the partitioning of resistances between vascular and extra‐vascular compartments remained unchanged despite extensive disruption of the palisade by leafminers (up to 50%). This finding suggests that water flow from the petiole to the evaporation sites might not directly involve the palisade cells. The analysis of the temperature dependence of R_lamina in terms of Q₁₀ revealed that at least one transmembrane step was involved in water transport outside the leaf vasculature. Anatomical analysis suggested that this symplastic step may be located at the bundle sheath where the apoplast is interrupted by hydrophobic thickening of cell walls. Our findings offer some support to the view of a compartmentalization of leaves into well‐organized water pools so that the transpiration stream would involve veins, bundle sheath and spongy parenchyma, while the palisade tissue would be largely by‐passed with the possible advantage of protecting cells from short‐term fluctuations in water status.