森林生态系统土壤碳库对氮沉降的响应研究进展

大气氮沉降的不断加剧,改变了土壤理化性质,直接影响植物的生长与发育,间接影响了陆地生态系统碳库,进而可能改变全球气候变化进程。森林是陆地生态系统的主体,因此,弄清氮沉降如何影响森林生态系统碳库,对预测全球气候变化具有重要意义。笔者旨在详细分析氮沉降对森林生态系统土壤碳库输入和输出的影响,阐述氮沉降对森林生态系统凋落物分解、细根周转和土壤呼吸的影响研究进展和作用机制。截至目前,关于氮沉降对于陆地生态系统的影响研究报道较多,且国内外诸多学者也在森林生态系统土壤碳库对氮沉降的响应领域开展了较多试验研究,但多集中于碳输入和输出的总量分析,而对输入和输出各个组分的研究相对较少。笔者综述了国内外有关森林生态系统碳库输入和输出各组分对氮沉降响应的相关研究,为进一步揭示其响应机制和途径提供参考依据。     

Determination and kinetics of enrofloxacin and ciprofloxacin in Tra catfish (Pangasianodon hypophthalmus) and giant freshwater prawn (Macrobrachium rosenbergii) using a liquid chromatography/mass spectrometry method

Determination and kinetics of enrofloxacin and ciprofloxacin in Tra catfish (Pangasianodon hypophthalmus) and giant freshwater prawn (Macrobrachium rosenbergii) using a liquid chromatography/mass spectrometry method. J. vet. Pharmacol. Therap. 34, 142-152. The fluoroquinolones enrofloxacin (EF) and ciprofloxacin (CF) residues were investigated in the edible tissues of two important Asian aquacultured species such as Tra catfish (Pangasianodon hypophthalmus) and giant freshwater prawn (Macrobrachium rosenbergii) using a sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry method. Fish and prawn were treated with medicated feed with multiple doses of EF, in field conditions. A validation study of the analytical method was realized in terms of linearity, specificity, precision (repeatability and within-laboratory reproducibility), recovery and decision limit (CCα). The time needed before the antibiotic disappears from animal tissues or reach the maximum residue limit (MRL, 100μg/kg) was assessed. The concentration values of EF detected in Tra catfish tissue were between the MRL and 2×MRL concentrations, according to the fish density, 7days following the end of the enrofloxacin treatment (20mg/kg body weight per day, for seven consecutive days). The concentration value of ER in prawn tissue was lower than the MRL and the limit of quantification (LOQ, 14μg/kg) 5 and 7days after the stop of the EF treatment (50mg/kg body weight per day, for five consecutive days), respectively. The mean detected levels of CF was much lower in comparison with that of EF, indicating that only a small part of EF is metabolized into CF (<5%) in both Tra catfish and prawn.     

Synergistic effects of Miconazole and Polymyxin B on microbial pathogens

The therapeutic value of antibiotics depends on the susceptibility of the infecting microorganism and the pharmacological profile of the drugs. To assess the value of an antibiotic combination of polymyxin B and miconazole this study examined the in vitro synergistic potential of the two drugs on Gram-negative and Gram-positive bacteria and yeast. Antifungal and antibacterial activity was tested by minimum inhibitory concentration (MIC) of broth macrodilution and urea broth microdilution, by fluorescence microscopy and flow cytometry. Synergism was calculated using the fractional inhibitory concentration index (FICi). With Staphylococcus intermedius as target we found up to an eightfold reduction of the individual MICs when both drugs were combined. However, the FICi was 0.63 suggesting no real interaction between the two drugs. With Escherichia coli, Pseudomonas aeruginosa, and Malassezia pachydermatis as targets the antimicrobial drug combination reduced the MICs of polymyxin B and miconazole from fourfold to hundredfold resulting in FICi between 0.06 and 0.5 which defines a synergistic action. Thus, if polymyxin B and miconazole are combined their effect is greater than the sum of the effects observed with polymyxin B and miconazole independently, revealing bactericidal and fungicidal synergism. Our results indicate a strong therapeutic value for the combination of these antimicrobial agents against Gram-negative bacteria and yeast and a weaker value against Gram positive bacteria for clinical situations where these pathogens are involved.     

散尾葵提取物成分分析及抑菌作用

利用超声波提取和气质联用分析法,对散尾葵的提取物进行了组分和含量分析。结果表明,提取物含酸类化合物2种,占提取物总量的1.20%;醇类化合物3种,占提取物总含量 1.78%;酯类化合物5种,占提取物总量的7.11%;烷类化合物5种,占提取物总量的13.27%;醚类化合物2种,占提取物总含量 3.36%;酮类化合物1种,占提取物总含量 0.41% 。利用散尾葵提取物对10种居室空气中收集的细菌进行了抑菌性测定,对其中7种具有抑菌活性,而对放线菌、动性球菌、冷杆菌无抑制作用。对葡萄球菌和枯草芽孢杆菌抑菌力最强,125mg/mL浓度提取液抑菌率达到100%。     

红池坝人工草地放牧方式和放牧强度的研究

在红池坝人工草地对放牧方式和放牧强度进行比较研究,同时对已给定的载畜量加以验证,以便制定该草地的最适放牧制度。研究结果表明,适于该地区的放牧管理制度是划区轮牧;各个阶段的载畜量与牧草生长速度之间的关系可用数学模型表示为:Y=179.5＋5.48X,在每公顷7.5个绵羊单位的载畜量下进行中度放牧强度可获得草地最大产草量,并保持其稳定。     

LFA—3和IL—2对机体免疫增强作用

以绵羊红细胞膜提取的ＬＦＡ－３和猪外周血单个核细胞所产生的ＩＬ－２，同时或分别与新城疫Ⅳ系疫苗胸肌注射２２日龄雏鸡，测定鸡体ＨＩ抗体效阶及Ｅｔｇ花环形成率的变化，结果表明，ＬＦＡ－３组抗体效价与对照组差异极显著，ＩＬ－２也可显著提高ＩＶ系苗免疫后ＨＩ抗体效价，且两者的作用具有剂量依赖性。     

根据个体间蛋白质多位点基因型的比较分析中国黄牛的遗传关系

现行群体间遗传距离的度量方法都以等位基因频率的计算为依据，这些方法的缺点之一是在位点不多，多态笥不高时要求群体有较大的取样个体数目，另外，这些方法所建造的树素图不能反映群体是由混血引起还是由长期进化引起这一问题，针对这些问题，本文提出了以个体间蛋白质多位点基因型比较为基础的群体间遗传距离和群体内基因杂合度的度量方法，以十个主要中国黄牛群体的遗传关系分析为例，比较圆满的解决了上面几个问题。     

扬子鳄胚胎背部皮肤及鳞甲的发生

本文观察了１６例不同时间的扬子鳄（Ａｌｌｉｇａｔｏｒｓｉｎｅｎｓｉｓ）胚胎背部皮肤及鳞甲的形态及组织发生过程。孵化第２０天，来自胚胎中胚层生皮节的间充质细胞开始向原始表皮下迁移，表皮仅具周皮层与生发层两层细胞。第２８天背部鳞片开始明显，左右鳞片之间出现很浅的鳞间沟，前后鳞片交界处的原始表皮、真皮层开始向外突出形成鳞甲原基。第３４天鳞甲原基突出伸长，第４０天背鳞的纵崤明显。第３４～５０天中，鳞甲后缘基部的表皮层向鳞甲前缘基部的真皮层不断内陷，鳞甲显著伸长并向体后方水平伸出。背部表皮在孵化第３４天出现三层细胞，第４０天周皮细胞中开始出现色素沉集。第５０天表皮具四层细胞，周皮层细胞中出现大量色素沉集。第６０天表皮分层与成体时相似，周皮层已退化。孵化第３４天真皮层细胞形态出现多样化，第４０天真皮可分上、下两层。第５０天真皮上层中形成交织的胶原纤维网，下层中形成平行走向的胶原纤维。本文简要讨论了扬子鳄鳞甲的形态发生特点。     

改革创新开拓蚕业现代化新局面

“十五”期间蚕业将面临从计划经济走向经济的重大改革。蚕茧流通体制改革、企业制度改革、事业单位改革都会给蚕业生产带来巨大冲击。蚕业必须深改革,加快体制创新和技术创新,从调整结构,形成专业化分工的区域区布局,探索桑地流转机制,扩大生产规模,加强生产基础,加快实用技术创新,实行产业化经营等方面入手,开拓蚕业现代化的新局面。     

<Emphasis Type="Italic">Echinococcus granulosus</Emphasis>: Immunoprotection accompanyied by humoral and cytokine response against secondary hydatidosis in mice immunized with r<Emphasis Type="Italic">Eg.</Emphasis>myophilin

Objects:  

This study aimed to investigate the immunoprotection of the recombinant Eg.myophilin (rEg.myophilin) and tentatively analyze mechanism of this protection.