稻纵卷叶螟的人工饲养技术

稻纵卷叶螟Cnaphalocrocis medinalis的人工饲养技术是科研人员顺利开展相关研究工作的前题.稻纵卷叶螟人工饲养所要解决和重视的关键问题是食料和饲养条件.目前主要以天然食料、人工饲料以及2种食料相结合的方法饲养稻纵卷叶螟.而饲养条件,如温湿度、饲养密度、化蛹介质、产卵介质等会对对稻纵卷叶螟的生长发育产生影响.本文对目前我国稻纵卷叶螟人工饲料及人工饲养技术进行综述,有助于厘清该虫人工饲养技术的发展脉络,促进人工饲养技术的改善和提高,推动我国稻纵卷叶螟的研究.     

Arginine vasopressin does not mediate heat loss in the tail of the rat

It has been reported that hypothermia induced by arginine vasopressin (AVP) is brought about by a coordinated response of reduced thermogenesis in brown adipose tissue (BAT) and increased heat loss through the tail of rats. However, it is well known that AVP is one of the strongest peripheral vasoconstrictors. Whether the AVP-induced hypothermia is associated with an increase in heat loss through the tail is questionable. Therefore, the present study assessed the relationship between the effects of AVP on tail skin temperature and the induced hypothermic response, and to determine if peripheral AVP administration increases heat loss from the tail. Core, BAT and tail skin temperature were monitored by telemetry in male Sprague–Dawley rats before and after intraperitoneal administration of AVP or vasopressin receptor antagonist. We also analyzed simultaneously of the time-course of AVP-induced hypothermic response and its relationship with changes in BAT temperature, and effect of AVP on grooming behavior. The key observations in this study were: (1) rats dosed with AVP induced a decrease in heat production (i.e., a reduction of BAT thermogenesis) and an increase of saliva spreading for evaporative heat loss (i.e., grooming behavior); (2) AVP caused a marked decrease in tail skin temperature and this effect was prevented by the peripheral administration of the vasopressin V1a receptor antagonist, suggesting that exogenous AVP does not increase heat loss in the tail of rats; (3) the vasopressin V1a receptor antagonist could elevate core temperature without affecting tail skin temperature, suggesting that endogenous AVP is involved in suppression of thermogenesis, but not mediates heat loss in the tail of rats. Overall, the present study does not support the conclusion of previous reports that AVP increased tail heat loss in rats, because AVP-induced hypothermia in the rat is accompanied by a decrease in tail skin temperature. The data indicate that exogenous AVP-induced hypothermia attributed to the suppression of thermoregulatory heat production and the increase of saliva spreading for evaporative heat loss.     

Ab Initio Quantum Mechanics Analysis of Imidazole C-H…O Water Hydrogen Bonding and a Molecular Mechanics Forcefield Correction

Abstract

While it is well established that classical hydrogen bonds play an important role in enzyme structure, function and dynamics, the role of weaker, but ‘activated’ C-H donor hydrogen bonds is poorly understood. The most important such case involves histidine which often plays a direct role in enzyme catalysis and possesses the most acidic C-H donor group of the standard amino acids. In the present study, we obtained optimized geometries and hydrogen bond interaction energies for C-H…O hydrogen bonded complexes between methane, ethylene, benzene, acetylene, and imidazole with water at the MP2-FC/6-31++G(2d,2p) and MP2-FC/aug-cc-pVDZ//MP2-FC/6-31++G(2d,2p) levels of theory. A strong linear relationship is obtained between the stability of the various hydrogen bonded complexes and both separation distances for H…0 and C—O. In general, these calculations indicate that C-H…0 interactions can be classified as hydrogen bonding interactions, albeit significantly weaker than the classical hydrogen bonds, but significantly stronger than just van der Waals interactions. For instance, while the electronic energy of stabilization at the MP2-FC/aug-cc-pVDZ//MP2-FC/6-31++G(2d,2p) level of theory of a water C-H…O water hydrogen bond is 4.36 kcal/mol more stable than the methane C-H…O water interaction, the water-water hydrogen bond is only 2.06 kcal/mol more stable than the imidazole C_e?H…O water hydrogen bond. Neglecting this latter hydrogen bonding interaction is obviously unacceptable. We next compare the potential energy surfaces for the imidazole C_e?H…O water and imidazole N_d?H…O hydrogen bonded complexes computed at the MP2/6-31++G(2d,2p) level of theory with the potential energy surface computed using the AMBER molecular mechanics program and forcefields. While the Weiner et al and Cornell et al AMBER forcefields reasonably account for the imidazole N-H…O water interaction, these forcefields do not adequately account for the imidazole C_e?H…O water hydrogen bond. A forcefield modification is offered that results in excellent agreement between the ab initio and molecular mechanics geometry and energy for this C-H…O hydrogen bonded complex.     

北京市怀沙-怀九河市级水生野生动物保护区鱼类物种多样性及其资源保护

怀沙河和怀九河是两条自然汇入北京怀柔水库的河流,被规划为北京市第一个市级水生野生动物保护区。2004年3月~2005年2月,作者对该保护区内野生鱼类资源进行了本底调查。调查区域内野生淡水鱼类共计24种(不计引入种),隶属于6目11科24属,以鲤形目鲤科鱼类为主,多为山区溪流小型鱼类。鱼类物种多样性在空间分布上有所不同,两河下游近水库河段物种多样性最高,这可能与两个不同生态环境交界处的边缘效应有关;其多样性在时间上春夏季高于秋冬季。结合区域内的生境特点,建议加强对核心区的保护力度,重新规划缓冲区和过渡区;在保护自然环境的同时,兼顾当地居民的经济利益,达到人与资源的和谐发展。     

小熊猫染色体异染色质的显示

以培养的小熊猫外周淋巴细胞为实验材料,结合Ｃ－显带技术及ＣＭＡ３／ＤＡ／ＤＡＰＩ三竽荧光杂色的方法,对小熊猫的染色体组型、Ｃ－带带型及ＣＭＡ３／ＤＡ／ＤＡＰＩ荧光带带型进行了研究,发现：（１）经Ｃ－显带技术处理,可在小熊猫染色体上呈现出一种极为独特的Ｃ－带带型。在多数染色体上可见到丰富的插入Ｃ－带及端粒Ｃ－带。而着丝区仅显示弱阳性Ｃ－带;（２）除着丝粒区外,ＣＭＡ３诱导的大多数强荧光带纹与Ｃ－阳性     

原位杂交检测lin-4 mRNA在Caenorhabditis elegans中的表达

lin-4是控制Caenorhabditis elegans(C.elegans)幼虫发育的异时性基因,也是一种小RNA分子(microRNA)。通过整体原位杂交检测小RNA lin-4在野生型和lin-14、lin-28突变体中的区域性表达,探讨lin-4在C.elegans发育时空控制中的作用。结果表明:lin-4 mRNA在胚胎发育的早期和中期表达,胚胎后期至L1期末没有表达,之后又持续表达,成虫中也可以检测到lin-4 mRNA的存在。在lin-14和lin-28突变体中,lin-4的表达基本与野生型一致,不受lin-14、lin-28基因突变的影响,说明lin-14和lin-28是lin-4的下游基因。     

条斑紫菜EST-SSR引物种间转移扩增真实性研究

当条斑紫菜EST-SSR引物在坛紫菜几个品系上进行种间扩增时,微卫星引物的扩增结果中也出现了多带形式。为了研究的假阳性问题,扩增产物被从胶上回收克隆测序。在回收的坛紫菜扩增产物中,同阳性对照条斑紫菜扩增产物大小相同的产物中有微卫星序列重复,但在大分子量的条带中却没有,显现出典型的假阳性问题。在坛紫菜扩增中产生的假阳性带不适合进行建立在微卫星突变基础上的遗传研究,然而,在确定相关的遗传性状后,这些引物也可以用来进行品系鉴定等遗传研究。     

Alphaproteobacteria dominate active 2-methyl-4-chlorophenoxyacetic acid herbicide degraders in agricultural soil and drilosphere

2-Methyl-4-chlorophenoxyacetic acid (MCPA) is a widely used phenoxyalkanoic acid herbicide and subject to aerobic microbial degradation. Earthworms stimulate both growth and activity of MCPA-degrading bacteria in soil. Thus, active MCPA degraders in soil and drilosphere (i.e. burrow walls, gut content and cast) were assessed by 16S rRNA stable isotope probing in soil columns under experimental conditions designed to minimize laboratory incubation biases. Agriculturally relevant concentrations of [(13) C]MCPA (20 μg g(dw) (-1)) were degraded in soil within 23 and 27 days in the presence and absence of earthworms respectively. Total 16S rRNA analysis revealed 73 operational taxonomic units indicative of active Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Gemmatimonadetes, Planctomycetes, Proteobacteria and Verrucomicrobia in soil and drilosphere derived material. Seven operational taxonomic units indicative of Alpha-, Beta-, Gammaproteobacteria and Firmicutes consumed MCPA-[(13) C]. Dominant consumers of MCPA-[(13) C] were Alphaproteobacteria (Sphingomonadaceae and Bradyrhizobiaceae) in soil and drilosphere. Beta- (Comamonadaceae) and Gammaproteobacteria (Xanthomonadaceae) were also important MCPA-[(13) C] consumers in burrow walls only, indicating that earthworms favour betaproteobacterial MCPA degraders. In oxic microcosms with bulk soil, burrow walls and cast, 20 and 300-400 μg g(dw) (-1) [(13) C]MCPA were consumed within 24 h and 20 days respectively. Gut contents did not facilitate the degradation of [(13) C]MCPA. Sphingomonadaceae dominated MCPA-[(13) C] consumers in bulk soil and burrow wall microcosms, while Beta- and Gammaproteobacteria (Burkholderiacea, Comamonadaceae, Oxalobacteraceae and Xanthomonadaceae) dominated MCPA-[(13) C] consumers in microcosms of cast, indicating that the latter taxa are prone to respond to MCPA in cast. The collective data indicated that Alphaproteobacteria are major MCPA degraders in soil and drilosphere.     

Morphology and Phase Behavior of Two-Component Lipid Membranes

The stability and shapes of domains with different bending rigidities in lipid membranes are investigated. These domains can be formed from the inclusion of an impurity in a lipid membrane or from the phase separation within the membrane. We show that, for weak line tensions, surface tensions and finite spontaneous curvatures, an equilibrium phase of protruding circular domains or striped domains may be obtained. We also predict a possible phase transition between the investigated morphologies.