Respiratory characteristics of the blood pigments of three worms from an intertidal mudflat

Abstract

Three worms living in an intertidal mudflat near Auckland have respiratory pigments with different oxygen-binding properties. The burrowing sipunculid Xenosiphon mundanus has hemerythrin contained within coelomic cells. Oxygen is co-operatively bound to the hemerythrin (Hill's coefficient, n, = 1.8), resulting in a sigmoidal oxygen-binding curve of high oxygen affinity (halfsaturation tension, P₅₀, = 7.0 mm Hg at pH 7.5 and 20°C). Oxygen release is regulated by pH, and the Bohr effect is quantified by Ф = Δ log P₅₀ / ΔpH = - 0.30. The errant polychaete Glycera sp. has hemoglobin-charged coelomocytes with low oxygen affinity (P₅₀ = 13.5 mm Hg at pH 7.3 and 20°C)? and the oxygen-binding curve is essentially hyperbolic and insensitive to pH. The burrowing polychaete Abarenicola affinis has a vascular (circulating) erythrocruorin which binds and releases much oxygen for small changes in PO₂ (Hill's n = 3.8) and is insensitive to pH (Ф = -0.09). The physiological properties of these pigments cannot be related to the availability of oxygen in the near-environment, or to the habits of the animals, but appear to be dictated by the level of body organisation, particularly with regard to the gas exchange surfaces.     

Progress in kalata peptide production via plant cell bioprocessing

Cyclotides are disulfide-rich mini-proteins with the unique structural features of a circular backbone and knotted arrangement of three conserved disulfide bonds. They typically comprise 28–37 amino acids and are produced from linear precursors, and translational modification via oxidative folding, proteolytic processing and N-C cyclization. Because these plant-derived peptides are resistant to degradation and do exhibit a diverse range of biological activities, they have become important agronomic and industrial objectives. Due to its tolerance to sequence variation, the cyclotide backbone is also potentially useful as a molecular scaffold for protein-engineering applications. Several production options are available for bioactive plant metabolites including natural harvesting, total chemical synthesis, and expression of plant pathways in microbial systems. For the cyclotides with low yields in nature, chemical complexity and lack of knowledge of the complete biosynthetic pathway, however, many of these options are precluded. Plant cell-culture technology shows promise towards the goal of producing therapeutically active cyclotides in quality and quantities required for drug development as they are amenable to process optimization, scale-up, and metabolic engineering. It is conceivable that plant-based production systems may ultimately prove to be the preferred route for the production of native or designed cyclotides, and will contribute towards the development of target-specific drugs.     

摄食水平对不同性别食蚊鱼仔幼鱼生长发育的影响

在实验室27℃水温下,研究了少食、中食和饱食三个摄食水平对0至25日龄雌雄食蚊鱼(Gambusia affinis)的生长发育特征和饵料利用效率的影响。26d饲养实验结束后,对试验鱼摄食和生长指标、臀鳍分化、性成熟及饵料转换效率进行分析。结果显示:到臀鳍开始分化时,饱食组雄鱼的累计摄食总能量和生长速度开始小于雌鱼,且随日龄的增加差异加大;随摄食水平的增加,0日龄仔鱼到臀鳍分化和性成熟的时间缩短。至实验结束,各摄食组的雄鱼均形成发育完善的生殖足,性腺都达到成熟状态;而雌鱼性成熟迟于雄鱼,且其性成熟更易受到摄食水平的影响,饱食组只有约50%的个体达到性成熟,少食组的卵母细胞则均处在小生长期。随着摄食水平的增加,雌雄鱼的体长、体重和干物质特定生长率均呈明显上升趋势,而干物质饵料转化效率则呈明显下降趋势;实验结束时,雌鱼的生长指标和干物质饵料转化率均大于雄鱼。以上结果表明,伴随臀鳍的分化,食蚊鱼在摄食、生长、发育、性成熟和应对食物丰度变化上表现出显著的性别差异。       

中菊头蝠中国三亚种的形态特征比较

比较了四川、广东和海南3地的中菊头蝠(Rhinolophus affinis)种群的外部和头骨形态差异。在测量23个外部可量性状以及22个头骨可量性状的基础上,运用统计分析软件SPSS12.0对其中12个外部可量性状以及22个头骨可量性状进行数理统计。主成分分析的结果表明四川、广东和海南3地的中菊头蝠在外部形态和头骨形态上均有明显差异,用判别分析对主成分分析结果的正确性进行验证,证明了中国的中菊头蝠划为喜马拉雅、华南、海南3个亚种是合理的。     

拟盘多毛孢属真菌的新种*

报导拟盘多毛孢属真菌的8个新种。这8个新种是:近似状拟盘多毛孢Pestalotiopsis affinis、山姜拟盘多毛孢P. alpiniae、见血封喉拟盘多毛孢P. antiaris、五桠果拟盘多毛孢P. dilleniae、广西拟盘多毛孢P. kuwangsiensis、莲拟盘多毛孢P. nelumbinis、木荷拟盘多毛孢P. schimae、和神秘果拟盘多毛孢P. synsepali。新种的模式标本保存在广西大学植保系标本室。     

广西鸟类一新纪录——白眶鹟莺

2006年12月,在广西西南部靖西县底定自然保护区考察时,采到一号雀形目鸟类标本,经鉴定为白眶鹟莺(Seicercus affinis),是广西鸟类新纪录。从2005年1月-2007年5月,在多次鸟类考察过程中都观察到野外活动的白眶鹟莺。在底定,白眶鹟莺通常多在常绿阔叶林的林下灌丛和山间农耕地周边的灌丛中活动,其栖息地海拔高度大致在500-700m。全世界记录有2亚种,我国现已知仅有白眶鹟莺的一个亚种分布。该标本经鉴定为Seicercus affinis intermedius。文中还就白眶鹟莺在中国的分布情况作了讨论。标本现保存于广西大学动物科学技术学院动物标本室。     

湿地景观格局与水文过程研究进展

湿地是由陆地和水生生态系统的各种生态过程在不同尺度上综合作用的结果,具有显著的空间异质性.景观格局分析作为主要研究工具,有助于理解空间上的生态学过程.湿地水文过程决定了各种湿地类型的形成与维持,影响湿地的生物类群,导致湿地景观格局变化.湿地生物对湿地水文过程及理化环境具有反馈作用,从而控制湿地水文过程.通过湿地景观格局变化对水文过程的影响以及湿地水文过程变化对湿地景观格局的作用等互相关联的2个方面,探讨湿地系统景观格局与水文过程间的耦合机制,将成为今后湿地研究中的重点.     

慈竹克隆种群能量动态研究

本文引用Ｈａｒｐｅｒ的构件结构理论,从克隆构件,克隆分株和克隆种群３个层次,系统探索我国特有种慈竹克隆种群能量动态,研究结果表明：慈竹克隆种群单位量能值变化随其生长季节,生长发育阶段和年龄不同而异,冬季单位能值升高,换叶期单位能值聚然下降;生殖阶段单位能值降低,但龄级间差异较大,慈竹克隆种群具整合作用。影响慈竹克隆种群能量变动的因素主要是大气温度,湿度和种群生殖与换叶等。     

Impact of introduced native herbivores on a Pistia stratiotes infestation close to the Paraná Delta in Argentina

Pistia stratiotes L. (Araceae) is an important weed in many waterways worldwide. The South American weevil Neohydronomus affinis Hustache (Coleoptera: Curculionidae) and the planthopper Lepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae) are specific herbivores of P. stratiotes. Both species, plus the oligophagous moth Samea multiplicalis Guenée (Lepidoptera: Crambidae), were released in a P. stratiotes-infested lake in the suburbs of Buenos Aires, Argentina, where previous sampling indicated that specific herbivores were absent. The weevil and the planthopper established and covered the whole lake in under two months. The moth may have also established but its numbers were very low and erratic. Plant cover, biomass per square metre, and individual plant size decreased markedly within a year after the release of the insects. Concomitantly, other floating macrophytes appeared in the lake. Insect abundance was related to mean monthly temperature and light hours, but not the other insect species. However, insect damage levels and the state of the plant population suggest that herbivory was the main factor in lowering the P. stratiotes populations. N. affinis and L. pistiae could be specific, damaging and compatible as biocontrol agents for P. stratiotes.