氢醌和双氰胺对种稻土壤N2O和CH4排放的影响

通过盆栽试验,研究了脲酶抑制剂氢醌（ＨＱ）、硝化抑制剂双氰胺（ＤＣＤ）及二者的组合（ＨＱ＋ＤＣＤ）对种稻土壤Ｎ２Ｏ和ＣＨ４排放的影响．结果表明,在未施麦秸粉时,所有施抑制剂的处理均较单施尿素的能显著减少水稻生长期供试土壤Ｎ２Ｏ和ＣＨ４的排放．特别是ＨＱ＋ＤＣＤ处理,其Ｎ２Ｏ和ＣＨ４排放总量分别约为对照的１／３和１／２．而在施麦秸粉后,该处理的Ｎ２Ｏ排放总量为对照的１／２,但ＣＨ４排放总量却较少差别．不论是Ｎ２Ｏ还是ＣＨ４的排放总量,施麦秸粉的都比未施的高出１倍和更多．因此,单从土壤源温室气体排放的角度看,将未腐熟的有机物料与尿素共施,并不是一种适宜的施肥制度．供试土壤的Ｎ２Ｏ排放通量,与水稻植株的ＮＯ－３Ｎ含量和土表水层中的矿质Ｎ量分别呈显著的指数正相关和线性正相关;ＣＨ４的排放通量则与水稻植株的生长量和土表水层中的矿质Ｎ量呈显著的线性负相关．在Ｎ２Ｏ与ＣＨ４的排放间,未施麦秸粉时存在着定量的相互消长关系;施麦秸粉后,虽同样存在所述关系,但难以定量化．     

浑太流域洪涝灾害及其治理方略

抚顺、鞍山、辽阳等在内的中部城市群提供年用水量７．０×１０９ｍ３的７０％［５］,对辽宁经济发展与生态环境建设具有至关重要的作用．本文试图剖析浑河、太子河洪涝灾害问题,找出其成因与特点,从生态与工程结合角度提出治理方略,为防洪减灾,振兴经济服务．２　洪涝灾害成因分析２．１　洪涝灾害的一般分析　　洪涝灾害是天降暴雨和下垫面综合作用的结果．它通常依赖气象、水文地理和生态环境三方面因素．气象因素主要指暴雨,包括雨量、雨强和降雨落区．暴雨主要受大气环境制约,目前人类难以左右．然而,通过人工控制增减局地降雨…     

用于脑缺血小鼠海马SOD1表达的改进灌注固定法

常规灌注固定法多用于兔和大鼠等较大动物,并存在一些不足。改进了灌注固定法流程、灌注溶液的配方、流速、用量以及灌注装置,将其用于在显微操作下制备的缺血再灌注C57BL/6N小鼠模型,并对其海马进行H.E染色和免疫组织化学SOD1基因表达。结果显示,改进的灌注固定法使组织切片结构更加清晰,海马免疫阳性神经元定位于胞浆。缺血再灌注组(24hI/R)海马神经元SOD1表达比假手术对照组(sham-o)减少,而高压氧治疗组(24hHBO)SOD1表达有所恢复。表明改进的灌注固定法用于缺血再灌注C57BL/6N小鼠海马SOD1基因表达效果良好,结果可靠。实验结果提示,高压氧的治疗机制之一可能是通过增加SOD1基因表达而实现的。     

共表达H5N1流感病毒M1和HA基因的DNA疫苗与腺病毒载体疫苗的小鼠免疫评价

为评价在小鼠体内表达流感病毒M1和HA基因诱导的免疫反应,制备共表达H5N1亚型禽流感病毒 (A/Anhui/1/2005) 全长基质蛋白1 (M1) 基因和血凝素 (HA) 基因的重组DNA疫苗pStar-M1/HA和重组腺病毒载体疫苗Ad-M1/HA,将其按初免-加强程序免疫BALB/c小鼠,共免疫4次,每次间隔14 d。第1、3次用DNA疫苗,第2、4次用重组腺病毒载体疫苗,每次免疫前及末次免疫后14 d采集小鼠血清用于检测体液免疫应答,末次免疫后14 d采集小鼠脾淋巴细胞用于检测细胞免疫应答。血凝     

C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability

DNA replication and its connection to M phase restraint are studied extensively at the level of single cells but rarely in the context of a developing animal. C. elegans lin-6 mutants lack DNA synthesis in postembryonic somatic cell lineages, while entry into mitosis continues. These mutants grow slowly and either die during larval development or develop into sterile adults. We found that lin-6 corresponds to mcm-4 and encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex. The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase. Induction of cell cycle entry and differentiation continues in developing mcm-4 larvae, even in cells that went through abortive division. In contrast to somatic cells in mcm-4 mutants, the gonad continues DNA replication and cell division until late larval development. Expression of MCM-4 in the epidermis (also known as hypodermis) is sufficient to rescue the growth retardation and lethality of mcm-4 mutants. While the somatic gonad and germline show substantial ability to cope with lack of zygotic mcm-4 function, mcm-4 is specifically required in the epidermis for growth and survival of the whole organism. Thus, C. elegans mcm-4 has conserved functions in DNA replication and replication checkpoint control but also shows unexpected tissue-specific requirements.     

A genetic map of Xenopus tropicalis

We present a genetic map for Xenopus tropicalis, consisting of 2886 Simple Sequence Length Polymorphism (SSLP) markers. Using a bioinformatics-based strategy, we identified unique SSLPs within the X. tropicalis genome. Scaffolds from X. tropicalis genome assembly 2.0 (JGI) were scanned for Simple Sequence Repeats (SSRs); unique SSRs were then tested for amplification and polymorphisms using DNA from inbred Nigerian and Ivory Coast individuals. Thus identified, the SSLPs were genotyped against a mapping cross panel of DNA samples from 190 F2 individuals. Nearly 4000 SSLPs were genotyped, yielding a 2886-marker genetic map consisting of 10 major linkage groups between 73 and 132 cM in length, and 4 smaller linkage groups between 7 and 40 cM. The total effective size of the map is 1658 cM, and the average intermarker distance for each linkage group ranged from 0.27 to 0.75 cM. Fluorescence In Situ Hybridization (FISH) was carried out using probes for genes located on mapped scaffolds to assign linkage groups to chromosomes. Comparisons of this map with the X. tropicalis genome Assembly 4.1 (JGI) indicate that the map provides representation of a minimum of 66% of the X. tropicalis genome, incorporating 758 of the approximately 1300 scaffolds over 100,000 bp. The genetic map and SSLP marker database constitute an essential resource for genetic and genomic analyses in X. tropicalis.     

气候变化背景下中国农业气候资源变化V.宁夏农业气候资源变化特征

基于1961-2009年宁夏21个气象站点的气象资料,分析了宁夏各区农业气候资源的时空变化趋势.结果表明:研究期间,宁夏各地气温逐渐升高,呈北高南低的空间分布特征,年均气温的气候倾向率为0.4℃·(10 a)-1;大部分地区年降水量呈逐渐减少趋势,年降水量的气候倾向率为4.26 mm·(10 a)-1;无霜期和作物生长季天数随着气候变暖逐渐延长;≥10℃积温在3200℃·d以上的区域向南扩展,宁夏适宜种植中晚熟水稻的区域有所扩大;2001-2009年,宁夏大部分地区适宜种植冬小麦,全区各地几乎都适宜种植春小麦;宁夏南部山区各地7月平均气温≤20℃的区域面积逐渐缩小,适宜种植马铃薯的地域也随之缩小.     

In vitro and in vivo antioxidant activity of exopolysaccharide fractions from Bifidobacterium animalis RH

The aim of the study was to purify the exopolysaccharides (EPS) produced from Bifidobacterium animalis RH, which was isolated from the feces of Bama centenarians in Guangxi of China, and evaluate their antioxidant activities in vitro and in vivo. 2 fractions, a neutral EPS fraction (EPSa) and an acidic EPS fraction (EPSb), were obtained and compared for antioxidative activity. In vitro, they both showed remarkable inhibition effect on lipid peroxidation and strong DPPH radical scavenging activity, hydroxyl radical scavenging activity, superoxide radical scavenging activity, in which the last two were measured by the electron spin resonance (ESR). In vivo, EPSa and EPSb were orally administrated for 30 days in a d-galactose induced aged mice model. As results, they both could significantly increase the activities of SOD, CAT and total antioxidant capacity (TAOC) in serums and glutathione GST in livers. They also could inhibit significantly the formation of MDA in serums and livers, and reduce the activity of MAO and lipofuscin accumulation in mice brain. Moreover, EPSb exhibited much higher antioxidant activities than EPSa in vitro and in vivo. The results suggested that EPS fractions of Bifidobacterium animalis RH had direct and potent antioxidant activities.     

木糖异构酶序列结构特点、耐热机理及分子改造研究进展

近年来,随着发展低碳经济的迫切需要,可再生资源利用研究方兴未艾,其中,构建充分利用木质纤维素水解产物木糖生产乙醇的重组菌成为研究热点.木糖异构酶由于不需要辅酶,成为构建利用木糖重组酵母的首选途径.文中对近年来木糖异构酶的研究进展进行了综述.首先介绍了木糖异构酶的基本性质、序列、结构和功能特性,然后对其耐热机理进行了总结归纳;重点阐述了基于序列及结构进行的酶分子改造研究,包括底物特异性改造、热稳定性改造等;同时,结合作者的研究经历,对如何提高嗜热木糖异构酶在常温下的活性进行了探讨.最后,对木糖异构酶的研究进展进行了总结和展望,对基于结构改善木糖异构酶催化活性及构建新型高效利用木糖生产乙醇的重组菌具有重要的指导意义.