倒刺鲃生活史各阶段的食性分析

2004年3月至2005年2月对分布在西江水系中上游广西柳江段龙江中的一种名贵经济鱼类——倒刺鲃(Spinibarbus denticulatus)生活史各发育阶段的食性进行了分析研究。采用常规生物学方法,测定了倒刺鲃生活史各发育阶段的消化道指数、肠长指数、食物充塞度、肥满度等生物学参数。通过其食物组成、出现率和饵料类群变动或更替的数量特征,细分出倒刺鲃各发育阶段的食性特点:仔鱼和稚鱼阶段为杂食性偏动物食性;早期幼鱼为明显的杂食性;青年鱼则趋向于杂食偏植物食性;成鱼才是真正意义上的草食性鱼类。倒刺鲃幼龄及青年个体在周年中保持2·0～5·0的食物充塞度,而成鱼的摄食强度则存在明显的季节变化,在1月的平均充塞度只有0·3,在10月则为5·0。倒刺鲃幼龄个体周年中肥满度变化不明显,条件系数全年维持在2·201～2·406;青年个体周年中的肥满度5～8月间维持相对稳定,平均条件系数的变幅为2·337～2·365,但从9～12月,条件系数逐渐从2·451逐渐增大到2·852,在1～4月,条件系数逐渐从2·693减小到2·306;成鱼的肥满度呈现明显的季节变化,7月的条件系数为1·775,12月的则高达2·894。在倒刺鲃的整个生活史中,藻类在消化道中的出现率均达100%,平均湿重百分比在25·0%以上,可能是其重要的食物类群。     

不同类型虾池的理化因子及浮游植物群落的调查

于2001年10月和2002年4月两次调查分析了高位池、低位池两种类型的南美白对虾养殖池的理化因子及浮游植物群落的特征.结果表明:低位池的营养盐浓度普遍高于高位池,而高位虾池的盐度则高于低位.盐度是影响两类虾池浮游植物群落特征的主要因素.盐度较小(<5)的养殖池中,蓝藻占优势,主要为微囊藻、平裂藻、水花束丝藻、色球藻等;盐度介于10～30的池中,硅藻占优势,主要为舟形藻、桥弯藻等.     

Annual mowing mitigates the negative legacy effects of N enrichment on grassland nutrient use efficiency

刈割能够缓解历史氮沉降对草地群落养分利用效率的负面影响 氮沉降的增加对草地生态系统结构和功能造成了诸多负面影响,包括改变植物群落结构和降低植物养分利用效率。许多国家的减排政策有效地减少了氮排放、降低了氮沉降速率,但历史氮沉降对生态系统的影响可能具有遗留效应。草地植物群落的养分利用效率在氮沉降减少或者停止后作出何种响应,还有待于研究。作为草地重要的管理方式之一,刈割将如何调控历史氮沉降对植物养分利用效率的影响仍然属于知识空白。本研究探讨了氮素添加停止以后连续3年内功能群水平和群落水平上植物的氮、磷利用效率对历史氮素添加和刈割处理的响应。研究结果表明,历史氮素添加显著降低了植物功能群水平的氮利用效率,但未改变其磷利用效率;在群落水平上,历史氮素添加显著降低了植物的氮磷利用效率。刈割能够缓解历史氮素添加对植物群落氮磷利用效率的降低作用,该作用主要是抑制具有较低养分利用效率的根茎型高禾草的生长而促进具有较高养分利用效率的丛生型高禾草的生长。研究结果揭示了植物群落结构在驱动植物群落养分利用效率变化中的重要作用。本研究认为适当的草地管理方式有助于氮沉降过后草地植物养分利用效率的恢复。     

The effects of warming and nitrogen addition on soil nitrogen cycling in a temperate grassland, northeastern China

Background

Both climate warming and atmospheric nitrogen (N) deposition are predicted to affect soil N cycling in terrestrial biomes over the next century. However, the interactive effects of warming and N deposition on soil N mineralization in temperate grasslands are poorly understood.

Methodology/Principal Findings

A field manipulation experiment was conducted to examine the effects of warming and N addition on soil N cycling in a temperate grassland of northeastern China from 2007 to 2009. Soil samples were incubated at a constant temperature and moisture, from samples collected in the field. The results showed that both warming and N addition significantly stimulated soil net N mineralization rate and net nitrification rate. Combined warming and N addition caused an interactive effect on N mineralization, which could be explained by the relative shift of soil microbial community structure because of fungal biomass increase and strong plant uptake of added N due to warming. Irrespective of strong intra- and inter-annual variations in soil N mineralization, the responses of N mineralization to warming and N addition did not change during the three growing seasons, suggesting independence of warming and N responses of N mineralization from precipitation variations in the temperate grassland.

Conclusions/Significance

Interactions between climate warming and N deposition on soil N cycling were significant. These findings will improve our understanding on the response of soil N cycling to the simultaneous climate change drivers in temperate grassland ecosystem.     

Functional analysis of the distal region of the third intracellular loop of PROKR2

Mutations in the G-protein-coupled receptor PROKR2 have been identified in patients with idiopathic hypogonadotropic hypogonadism (IHH) and Kallmann syndrome (KS) manifesting with delayed puberty and infertility. Recently, the homozygous mutation V274D was identified in a man displaying KS with an apparent reversal of hypogonadism. The affected amino acid, valine 274, is located at the junction region of the third intracellular loop (IL3) and the sixth transmembrane domain (TM6). In this study, we first studied the effect of V274D and related mutations (V274A, V274T, and V274R) on the signaling activity and cell surface expression of PROKR2. Our data indicate that a charged amino acid substitution at residue 274 of PROKR2 results in low cell surface expression and loss-of-function. Furthermore, we studied the effects of two clusters of basic amino acids located at the proximal region of Val274 on the cell surface expression and function of PROKR2. The deletion of RRK (270–272) resulted in undetectable cell surface expression, whereas RKR (264–266)-deleted PROKR2 was expressed normally on the cell surface but showed loss-of-function due to a deficiency in G-protein coupling. Our data indicate that the distal region of the IL3 of PROKR2 may differentially influence receptor trafficking and G-protein coupling.     

A new 4-(2-methylquinolin-4-ylmethyl)phenyl P1' group for the beta-amino hydroxamic acid derived TACE inhibitors

A new P1' group for TACE inhibitors was identified by eliminating the oxygen atom in the linker of the original 4-(2-methylquinolin-4-ylmethoxy)phenyl P1' group. Incorporation of this 4-(2-methylquinolin-4-ylmethyl)phenyl group onto different beta-aminohydroxamic acid cores provided compound 18, which demonstrated potent porcine TACE (p-TACE) and human whole blood activity, excellent PK properties, and good selectivity against a variety of MMPs.     

拥挤胁迫对史氏鲟稚鱼血浆溶菌酶活性和补体水平的影响

鱼类主要依赖先天性免疫反应或称非特异性免疫反应来保护自己,其非特异性免疫反应似乎比某些高等脊椎动物更有潜力,因此探讨非特异性免疫反应是必要的。在鱼类的养殖过程中,会发生各种的应激反应,急性胁迫结果是打乱代谢平衡,使用于生长的能量转移到适应外界环境的生理转变中,慢性胁迫更是会使能量耗竭。鱼类处于慢性胁迫时常表现出免疫抑制,尽管其机理尚未完全揭示,     

周期性断食对凡纳滨对虾摄食、生长和排粪的影响

凡纳滨对虾(Litopenaeus vannamei)具有生长快、环境适应力强、适合进行集约化养殖等优点,现已成为我国沿海甚至内陆地区对虾养殖的主要品种.     

Identification of pyrrolo[2,1-f][1,2,4]triazine-based inhibitors of Met kinase

An amide library derived from the pyrrolo[2,1-f][1,2,4]triazine scaffold led to the identification of modest inhibitors of Met kinase activity. Introduction of polar side chains at C-6 of the pyrrolotriazine core provided significant improvements in in vitro potency. The amide moiety could be replaced with acylurea and malonamide substituents to give compounds with improved potency in the Met-driven GTL-16 human gastric carcinoma cell line. Acylurea pyrrolotriazines with substitution at C-5 demonstrated single digit nanomolar kinase activity. X-ray crystallography revealed that the C-5 substituted pyrrolotriazines bind to the Met kinase domain in an ATP-competitive manner.     

百合科多肉植物美吉寿的组织培养与快速繁殖

1植物名称 Haworthia emelyae var．major（G．G．Smith）M．B．Bayer,中文惯称美吉寿。 2材料类别 成年美吉寿春生花茎子房部位,实验材料来源于Mesagarden公司。 3培养条件（1）启动培养基：MS＋6-BA0．5mg．L^-1（单位下同）＋KT1＋NAA0．1;（2）分化培养基：MS＋6-BA1＋KT2;（3）继代与增殖培养基：MS＋6-BA0．5＋NAA0．05;（4）复壮与生根培养基：1／2MS＋NAA0．1。