嗜热梭菌内切纤维素酶的表达及其酶特性研究

通过PCR克隆了嗜热梭菌内切纤维素酶基因,该基因ORF为1 947 bp,经Blast分析,该序列与嗜热梭菌同源性最高(93%),构建了内切纤维素酶大肠杆菌基因工程菌. SDS-PAGE电泳结果表明,在分子量77 000左右有表达蛋白条带,该工程菌最适酶活性为90 U/ml,是出发菌的2.8倍,最适温度在60 ℃左右,最适pH为8.     

大型医院图书馆的生存危机与相应对策

对大型医院图书馆在当前医院发展中的困境进行了分析,并对医院图书馆如何摆脱制约,开拓创新,谋求长远发展进行了探讨。

     

崇明东滩湿地土壤有机碳空间分异特征及影响因素

为了解不同类型湿地土壤有机碳含量的空间分异特征,以长江口崇明东滩不同植被类型和冲淤性质的湿地土壤为研究对象,测定3种土壤中有机碳含量、微生物量、以及与碳代谢相关的土壤酶活性,分析不同类型湿地土壤有机碳含量的空间变异特征,并对其影响因素进行了讨论.结果表明,不同类型湿地土壤的有机碳含量在不同潮间的变化趋势基本一致,呈现出高潮滩>中潮滩>低潮滩>光滩,即高潮滩具有较强的有机碳汇聚能力.3种不同类型湿地土壤有机碳含量的空间变异性较大,其特征表现为:芦苇型沙质土-A区[(4.34±1.30)g·kg-1]<芦苇/互花米草混合型粘质土-B区[(7.35±1.63)g·kg-1]<芦苇/互花米草型粘质土-C区[(9.17±1.18)g·kg-1],A区有机碳含量空间变异系数最大为52%,C区最小为22%,而且有机碳空间分异受湿地土壤微生物数量、酶活性以及土壤含水、含盐量的影响.芦苇型沙质土-A区有利于微生物的呼吸、代谢与繁殖,具有较高的有机碳代谢能力,而芦苇/互花米草型粘质土-C区则更有利于有机碳的保留.研究结果用于阐明不同类型湿地土壤的有机碳保留能力,进而为湿地的管理与优化提供理论基础和决策依据.     

黄曲霉和黑曲霉发酵麻疯树废弃饼粕产蛋白酶的酶学性质初探

通过对黄曲霉和黑曲霉发酵麻疯树废弃饼粕所产蛋白酶的酶学性质进行初步研究,确定黄曲霉所产蛋白酶最适催化温度为45℃;最适pH值为6．0;Vmax=3333．33μg&#183;min^-1,Km=31．25mg&#183;mL^-1;Fe^3＋能对其活力产生强烈的抑制作用;适量有机溶剂对蛋白酶活力有一定促进作用。黑曲霉所产蛋白酶最适催化温度为50％;最适pH值为4．0;Vmax=18．05μg&#183;min^-1,Km=2．23mg&#183;mL^-1;有机溶剂对蛋白酶活力有一定促进作用;Na^＋和Hg^2＋对蛋白酶活力则有十分强烈的抑制作用。     

Soil properties, grassland management, and landscape diversity drive the assembly of earthworm communities in temperate grasslands

Earthworms are widespread soil organisms that contribute to a wide range of ecosystem services. As such, it is important to improve our knowledge, still scanty, of the factors that drive the assembly of earthworm communities. The aim of the present study was to conjointly evaluate the effects on the assembly of earthworm communities of i) soil properties (texture, organic matter content, and pH), ii) grassland management (grassland age, livestock unit, and type of fertilization), iii) landscape diversity (richness, diversity of surrounding habitats, and grassland plant diversity), and iv) presence of hedgerows. The study was conducted in temperate grasslands of Brittany, France. Earthworms were sampled in 24 grasslands and, in three of these grasslands, they were sampled near a hedgerow or near a ditch (control without a hedgerow). Soil properties explained the larger portion of the variation in the earthworm community parameters compared to grassland management or landscape diversity. The increase in soil organic matter content and pH were the most favorable factors for earthworm abundance and biomass, in particular for endogeic species. Regarding grassland management, the increase in the livestock unit was the most damaging factor for earthworm communities, in particular for the anecic earthworm biomass and endogeic species richness. Surprisingly, landscape diversity negatively affected the total earthworm abundance and epigeic earthworm biomass, but it was related to an increase in the epi-anecic species. At a finer scale, we also demonstrated that the presence of hedgerows surrounding grasslands enhanced earthworm species richness, especially within the epigeic and anecic ecological categories. This study highlights that the earthworm ecological categories respond specifically to environmental filters; further studies need to be conducted to elucidate the factors that drive the assembly of earthworm communities at this ecological category level. We recommend that policymakers should act on landscape management to favor earthworm diversity in order to improve the ecosystem services they drive.     

The Expression Characteristics of MYNN Gene in Different Tissues and Muscles of Pig

This study was aimed to investigate the expression characteristics of myoneurin (MYNN) gene in different tissues and its developmental expression in muscles (longissimus dorsi, biceps femoris and psoas major), cerebellum, liver, pancreas, kidney, stomach, spleen and lung tissues of pigs. The expression characteristics of MYNN mRNA in 11 different tissues including heart, liver, spleen, lung, kidney, cerebellum, small intestine, pancreas, stomach, biceps femoris and fat of Large White pigs and Mashen pigs at the age of 90 days and the developmental expression patterns in muscle, cerebellum, liver, pancreas, kidney, stomach, spleen at three strages (1, 90, 180 days) of Large White pigs and Mashen pigs were studied by Real-time PCR. The results showed that MYNN was widely expressed in various tissues of pigs, and there was significant difference among the tissues(P < 0.05; P < 0.01); The expression of MYNN in muscle, liver, pancreas, cerebellum, kidney, stomach, spleen, lung tissues were significant difference at three development stages of Large White pigs and Mashen pigs(P < 0.05; P < 0.01), and also had a specific rule, which indicated that it may play an important role in these pig tissues. The expression of MYNN gene could related to the tissue, age and the genetic background of breeds. The results of this study provided a better understanding of the biological functions of pig MYNN. Further studies are required to determine its molecular mechanisms, especially in the regulation of skeletal muscle development.     

超高效液相色谱-串联质谱法快速测定生咖啡豆中多菌灵等农药残留

建立了生咖啡豆中多菌灵、克百威、甲霜灵、马拉硫磷、乐果、亚胺硫磷农药残留的超高效液相色谱-串联质谱(UPLC-MS/MS)测定方法。样品通过乙腈超声提取,在电喷雾离子化正离子方式(ESI+)及多反应监测模式(MRM)下进行测定,基质配标准溶液外标法定量。在优化试验条件下,方法的线性范围为0.01～0.50 mg/L,相关系数r>0.99,定量限为0.001～0.010 mg/kg;在加标水平为0.05、0.50、2.50 mg/kg时,平均回收率范围为77.7%～110.0%,相对标准偏差为1.3%～9.9%,满足定量分析的要求。     

湖北太子山兰考泡桐引种栽培试验

为优化太子山树种林种结构,进行了兰考泡桐引种栽培试验。苗木截干后栽植,设置了株行距为3 m×3 m和2 m×3 m的初植密度试验。经当年平茬及第3年间伐强度为40%和第5年隔行间伐的透光伐,对不同密度的兰考泡桐6年生长情况进行了分析。结果表明:兰考泡桐在试验区引种栽培初步成功,树高、胸径和单株材积年均生长量分别达到2.09 m、3.28 cm和0.024 0 m3,明显优于当地杉木二代林的生长量,表现出速生丰产的特点;栽植密度对兰考泡桐的胸径和材积生长有显著影响,以3 m×3 m或密度更大的林分生长较好。     

越南生物多样性现状及保护对策

越南得天独厚的地理位置及气候特点决定了其生物多样性极其丰富。但近年来人为因素使越南的自然环境和资源遭到严重破坏,使越南的生物多样性呈现加速下降趋势。本文介绍了越南的生物多样性现状并分析其减少的原因,同时提出越南生物多样性保护的对策。     

梨不同树形对光效能及产量品质的影响

 针对乔砧老梨园高接换优后因树形不同产生的效益差距问题,通过对4种高接后不同树形乔砧梨园的枝量、冠层透光率、光和参数、叶片养分、产量和品质等相关数据进行了连续两年的调查研究,筛选并确定经济效益较高的适宜树形。研究结果表明：4种树形在总枝量、短枝量及短枝/总枝量基本均衡的前提下,树冠内不同部位的透光率、有效光辐射和叶片的净光合速率、鲜样质量、养分含量均有显著差别,进而导致不同树形间果实产量和品质的差异。综合分析认为,乔砧大冠梨园改造转形宜选单层开心形,而中小冠梨树高接换优宜采用细纺锤形。