干旱胁迫对烟草叶片丙二醛含量和细胞膜透性的影响

对干旱胁迫下5个烟草品种(系)丙二醛含量和细胞膜透性进行测定表明,随着干旱胁迫的不断加重,烟草叶片丙二醛含量呈现先升后降的趋势,而细胞膜透性则表现为持续升高;复水后细胞膜透性能很快恢复正常,而丙二醛含量需要较长时间才略有恢复。细胞膜透性反应了烟草受干旱胁迫的程度,而丙二醛含量的稳定对烟草的抗旱性有重要意义。     

禁食对小鼠体重、SOD和丙二醛含量的影响

给小鼠禁食4天后观察体重、肝SOD和心肌丙二醛的影响。结果表明,禁食期间小鼠的体重明显减轻,复食后体重很快恢复;肝脏SOD的活性明显提高,心肌丙二醛的含量显著下降。提示短期禁食具有抗衰老的效应,可提高机体的生存能力。     

梅花鹿和马鹿血浆纤维蛋白原的测定

梅花鹿(Cervus nippon)和马鹿(Cervus elaphus)为我国主要产茸鹿种。锯茸时出血很多,但很快止血并形成血痂,不发生因失血致死现象。产生这种现象的机制,除血液中其它凝血因子外,与鹿血浆纤维蛋白原的含量有关。目前尚未见到国内外关于梅花鹿和马鹿血浆纤维蛋白原含量的报道。 本研究用盐析和分光光度法,根据Lambert-Beer定律     

复合叶面肥对油桃和葡萄生长生理及果树品质的影响

我国北方一些地区因土壤pH高,导致其中有效性微量元素含量很低而不能满足果树植物的正常生长发育,进而导致严重的缺素症。通过土壤直接施肥或通过灌溉水将化肥施入土壤,肥料中的微量元素很快会被土壤固定,因而这些方法不能有效地解决缺素症问题。作者用5年时间研制成功了应用果树植物的系列复合叶面肥,这些叶面肥不仅含有植物所需的大量元素,而且含有微量元素、有机营养及植物生长调节剂;叶面肥的配方也因果树植物种类生长习性的不同而异。以油桃和葡萄为试材,喷施复合叶面肥72h后,叶片中叶绿体含量、硝酸还原酶活性、铁和锌含量显著提高;叶面肥还能增进油桃和葡萄果实品质,促进葡萄枝芽增重,但不会引起葡萄树体徙长。整个生长季节喷施复合叶面肥对树体均有益,但喷施间隔时间不应少7-10d。     

豌豆种子萌发时的含水量对子叶中蛋白酶和淀粉酶活性的影响

不同含水量的豌豆种子在饱和水蒸气中保持7d,在此过程中,当含水量低于萌动临界含水量时,限制了子叶中淀粉酶长寿mRNA的转译;含水量达到或超过萌动临界含水量时,子叶中淀粉酶长寿mRNA的转译得以进行,但转译程度因含水量不同而异,正常生长的轴器官是吸收子叶中蛋白质和淀粉水解产物的动力库,子叶中氨基酸含量的变化灵敏地调节着蛋白酶的活性,从而影响着蛋白质的动员程度,当环境中供水不足时,发现子叶中还原糖积累很快,非还原糖含量几乎没有变化,因此,认为对淀粉酶活性起灵敏调节作用的主要是还原糖。     

转反义Wx基因水稻颖果中与淀粉合成和积累相关酶活性的变化

将反义Wx基因转入水稻,导致Wx蛋白不同程度减少,颖果中的直链淀粉含量不同程度下降,总淀粉含量显著降低,直链淀粉与总淀粉的比值极显著降低。在水稻颖果发育过程中,ADPG-PPase、GBSS、SSS和SBE的活性在灌浆前期迅速升高,达最大值后很快下降,在灌浆中后期下降趋缓。Wx蛋白减少后的转基因水稻颖果中的GBSS活性明显下降,下降幅度与直链淀粉含量相一致,而且活性高峰期比其亲本有所提前。转基因水稻颖果中ADPG-PPase和SSS的活性在颖果发育的前中期,SBE则在中后期高于相应的亲本。     

丁草胺对水稻土甲烷释放和厌氧细菌的影响

近年来,我国水稻田的化除面积增加很快,除草剂的使用已成为一种必不可少的手段。因而除草剂大量使用的环境污染问题日益突出,对生态系统的平衡产生威胁性影响,引起农产品农药含量超标,或者即使不超标也由于食物链的生物富集最终进入人体危害健康。除草剂致癌、致突变和致畸胎的事实不胜枚举。除草剂在水稻田使用,至少有70％进入土壤,直接影响土壤微生物的生长和代谢。     

土壤水分和氮素有效性对刺槐幼苗叶片活性氧产生和清除的影响

采用施加氮肥和人工控水的方法,以一年生刺槐幼苗为材料进行盆栽实验,探讨提高土壤氮素含量对不同土壤水分条件下刺槐幼苗叶片中活性氧产生和清除的影响。结果表明:(1)相同氮素水平下,降低土壤水分含量引起刺槐生物量和叶片光合色素含量降低,而过氧化氢(H2O2)含量升高;抗氧化酶系统中的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性和过氧化氢酶(CAT)活性不同程度降低;抗氧化剂中抗坏血酸(ASA)含量和还原型谷胱甘肽(GSH)含量均有所提高;MDA含量逐渐升高,而同期细胞膜相对电导率显著升高。(2)相同水分条件下,提高土壤氮素水平显著提高了刺槐幼苗叶片光合色素含量,同时也一定程度提高了总生物量,显著降低了H2O2含量;SOD、POD和CAT活性不同程度升高;ASA含量和GSH含量则表现出不同程度下降;相对电导率显著降低同时MDA含量一定程度降低。因此,增加土壤氮素有效性可显著提高刺槐幼苗叶片光合色素含量,显著抑制活性氧的产生,一定程度提高总生物量和抗氧化酶活性,降低膜脂过氧化程度,从而有利于缓解干旱引起的伤害。     

麦红吸浆虫滞育发生和解除过程中总脂和甘油三酯含量变化

【目的】脂类与昆虫滞育密切相关。本研究旨在明确麦红吸浆虫Sitodiplosis mosellana (Géhin)滞育过程中脂类物质含量的变化规律,探讨麦红吸浆虫滞育与脂类物质变化的关系。【方法】采用香兰素硫酸显色法测定了2008年5月－2010年1月不同时间陕西杨凌养虫圃内麦红吸浆虫滞育前、滞育期及滞育解除后幼虫和蛹体内总脂和甘油三酯含量。【结果】 滞育前幼虫总脂和甘油三酯含量分别为378.12和291.67 μg/mg,显著高于整个滞育期（P<0.05）。滞育年周期中,冬季总脂和甘油三酯含量最高,翌年1月结茧幼虫二者含量分别为335.29 和275.72 μg/mg,显著高于其他季节（P<0.05）;整个滞育期间,裸露幼虫和结茧幼虫总脂和甘油三酯随季节变化趋势相同,但同期结茧幼虫含量高于裸露幼虫;滞育当年与第2年同期幼虫总脂和甘油三酯含量差异不显著（P>0.05）。滞育解除后,总脂和甘油三酯含量随着幼虫的发育和变态逐渐降低,其中中蛹和后蛹显著低于活动幼虫（P<0.05）。【结论】麦红吸浆虫滞育不同时期幼虫及蛹总脂和甘油三酯含量存在明显差异,其滞育与脂类物质的含量密切相关。     

保安湖沉积物和间隙水中氮和磷的含量及其分布

保安湖沉积物中氮(N)的含量平均为5.20mg/g,平面分布以桥墩湖区含量最高。沉积物中磷(P)的含量平均为0.75mg/g,平面分布以扁担塘湖区含量最高。沉积物间隙水中总氮的平均含量为3.63mg/L,无机氮中以氨氮的含量最高,占总氮的57.2%;间隙水中总磷的含量平均为0.098mg/L,磷酸盐占总磷的50.0%.间隙水中氮和磷含量的平面分布差异不明显。间隙水中氮和磷的含量比湖水中含量高,但除氨氮外,一般不超过5倍,表明湖水和沉积物间隙水之间营养交换十分强烈。       

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Molecular characterisation of species and genotypes of Cryptosporidium and Giardia and assessment of zoonotic transmission

The molecular characterisation of species and genotypes of Cryptosporidium and Giardia is essential for accurately identifying organisms and assessing zoonotic transmission. Results of recent molecular epidemiological studies strongly suggest that zoonotic transmission plays an important role in cryptosporidiosis epidemiology. In such cases the most prevalent zoonotic species is Cryptosporidium parvum. Genotyping and subtyping data suggest that zoonotic transmission is not as prevalent in the epidemiology of giardiasis. Molecular characterisation of Cryptosporidium and Giardia is a relatively recent application that is evolving as new genes are found that increase the accuracy of identification while discovering a greater diversity of species and yet unnamed taxa within these two important genera. As molecular data accumulate, our understanding of the role of zoonotic transmission in epidemiology and clinical manifestations is becoming clearer.     

Synthesis and turnover of cerebrosides and phosphatidylserine of myelin and microsomal fractions of adult and developing rat brain.

The synthesis and turnover of cerebrosides and phospholipids was followed in microsomal and myelin fractions of developing and adult rat brains after an intracerebral injection of [U-14C]serine. The kinetics of incorporation of radioactivity into microsomal and myelin cerebrosides indicate the possibility of a precursor-product relationship between cerebrosides of these membranes. The specific radioactivity of myelin cerebrosides was corrected for the deposition of newly formed cerebrosides in myelin. Multiphasic curves were obtained for the decline in specific radioactivity of myelin and microsomal cerebrosides, suggesting different cerebroside pools in these membranes. The half-life of the fast turning-over pool of cerebrosides of myelin was 7 and 22 days for the developing and adult rat brain respectively. The half-life of the slowly turning-over pool of myelin cerebrosides was about 145 days for both groups of animals. The half-life of the rapidly turning-over microsomal cerebrosides was calculated to be 20 and 40 h for the developing and adult animals respectively. The half-life of the intermediate and slowly turning-over microsomal cerebrosides was 11 and 60 days respectively, for both groups of animals. The amount of incorporation of radioactivity into microsomal cerebrosides from L-serine was greatly decreased in the adult animals, and greater amounts of the precursor were directed towards the synthesis of phosphatidylserine. In the developing animals, considerable amounts of cerebrosides were synthesized from L-serine, besides phosphatidylserine. The time-course of incorporation indicated that a precursor-product relationship exists between microsomal and myelin phosphatidylserine. The half-life of microsomal phosphatidylserine was calculated to be about 8 h for the fast turning-over pool in both groups of animals.     

Identification and composition of the tonsillar and anal enterococcal and streptococcal flora of dogs and cats

Enterococcus faecalis was the most frequently isolated enterococcal species from anal swabs and tonsils of dogs and cats, although in the anal samples from dogs Ent. hirae was found almost as often as Ent. faecalis. Most Ent.faecium strains from dog tonsils differed from those associated with humans and other animals in that they fermented sorbitol. Typical Ent. avium as well as atypical Ent. avium -like strains were seen in dogs, while the related species Ent. raffinosus was associated with cat tonsils. Enterococcus cecorum also occurred mainly in cats. Certain atypical strains, presumptively identified as Ent. cecorum , shared characteristics with Ent. columbae.
The most frequent streptococcal species in tonsils of cats and dogs were Streptococcus suis and Strep. canis. Streptococcus canis and Strep. bovis predominated in anal swabs. The canine Strep. suis differed from the common porcine strains in fermenting mannitol.
Forty-seven of the 288 isolates examined could not be identified or related to known species. The characteristics of two groups of these bacteria, provisionally called 'Ton 31 group' and 'O7 group' are described.     

颧骨颧弓骨折的分类及诊治

颧骨颧弓骨折是最常见的面中部骨折之一,迄今为止,在其分类及诊治的选择上仍然存在一定争议,本文对目前颧骨颧弓骨折的分类及诊治的现状和进展作一综述,以期对临床工作提供参考。