微生物反硝化及其电化学强化研究进展

微生物反硝化过程是在硝酸盐还原酶、亚硝酸盐还原酶、一氧化氮还原酶、一氧化二氮还原酶及其他一些脱氢酶的作用下,将电子供体的电子传递给NO3-的过程.在此综述了反硝化的各种电子供体及各种碳源.根据碳源的不同,反硝化菌可分为异养型反硝化菌和自养型反硝化菌.针对反硝化的过程,可以通过提供电子供体、加入电子载体、提高酶活性、加速辅酶再生、电刺激提高微生物活性等方法来强化反硝化过程.     

公羊生殖保健对供体母羊超数排卵的影响

为探讨肉用种公羊生殖保健技术对胚胎移植供体母羊超数排卵的影响,本研究以纯种萨福克肉用种公羊为实验材料,分别用保健和未保健种公羊对相同超排方法供体母羊实施常规人工输精和内窥镜输精,对比其超排效果。实验结果表明,内窥镜输精获胚率较高（P〈0.01）,经过保健的公羊处理的供体母羊获胚率高（P〈0.05）,各实验组间胚胎移植妊娠率之间无显著性差异（P〉0.05）。     

青花菜小孢子供体与 DH 群体性状相关性初步研究

比较了青花菜小孢子培养不同供体的DH群的性状表现,结果发现,供体双亲的性状决定了后代群体性状分离的程度,双亲差异程度越大,DH植株分离类型越多,并且具有明显的超亲优势。因此,在小孢子培养DH群体中,要想培养出类型多样的优良再生株系,供体的选择十分重要。     

Impact of plant genetic resources on wheat breeding

This article describes the impact of plant genetic resources on wheat breeding. It defines the important contribution of N.I. Vavilov Institute (St. Petersburg, Russia) to broadening the genetic diversity of new wheat cultivars. Special attention is given to conducting a comprehensive evaluation of intraspecific variability for valuable characters, including: 1) formation of special subcollections, consisting of accessions with useful characters and accessions representing intraspecies diversity for a given character; 2) revealing genetic differences among phenotypically superior accessions; 3) determining a genetic system of intraspecific variability for a given character; 4) formation of a genetic collection; 5) revealing and developing the donors of useful characters. An example using plant height shows that the proposed research approach adequately determines the genetic potential of species and reveals the most effective genes for practical uses. It is assumed that the main sources of genes for breeding Triticum aestivum L. in order of importance will remain: 1) intraspecific diversity of T. aestivum itself; 2) other Triticum species; 3) other genera of the Triticeae Dum. tribe (particularly Aegilops L.); 4) more remote genera of the Poaceae Barnh. botanical family. It is stressed that existing diversity of T. aestivum has been poorly investigated genetically and only partially used by breeders. Properly evaluated, it can provide multiple solutions for traditional and new problems of wheat improvement. This revised version was published online in August 2006 with corrections to the Cover Date.     

聚乙烯吡咯酮与促卵泡素对奶牛活体采卵效率的影响

采用4×4拉丁方设计,研究聚乙烯吡咯酮(PVP)溶解促卵泡素(FSH)一次肌肉注射对奶牛活体采卵效率和体内血清FSH含量的影响。将8头荷斯坦空怀母奶牛随机分为4组,每组2头,分别用5mgFSH 5mL15%PVP(15%PVP组)、5mgFSH 5mL30%PVP(30%PVP组)、5mgFSH 5mL生理盐水(对照组)和常规注射FSH(常规组)处理供体奶牛。试验期4个月,每月处理1次,各组均为处理后4d应用B型超声波导引采卵。结果如下:30%PVP组每头次平均可采卵泡9个,获可用卵母细胞4枚,与常规组比较差异不显著(P>0.05),但与对照组比较差异显著(P<0.05);15%PVP组每头次平均可采卵泡6个,获可用卵母细胞2.25枚,与对照组比较差异显著(P<0.05);体内血清FSH浓度,30%PVP组与常规组变化趋势相似,维持适宜FSH浓度时间较长,15%PVP组次之,而对照组注射后4~12h血清FSH浓度较高,以后急剧下降,表明PVP可延长FSH在体内存留时间,但以30%PVP效果最佳。     

Effect of donor plant age and inflorescence age on microspore culture of Brassica napus L.

Summary Effect of age of donor plants and age of inflorescence on embryogenesis in microspore culture of B. napus was examined. Microspores isolated from buds of older plants had a higher embryo yield than those of younger ones. The effect of the age of inflorescence showed a different pattern. In older plants, a higher embryogenesis response was observed in microspores isolated from buds of new inflorescences, while in young plants, microspores isolated from buds of old inflorescences showed high embryo yield. These different responses were considered to be attributable to a difference in the developmental stage of pollen at the time of microspore isolation. Our results indicated that microspores collected from older inflorescences and older plants have sufficient embryogenic potential when the optimum developmental stage of pollen was used. Frequency of embryo to plant conversion was influenced by the size of embryos subcultured, but not by donor plant age or the age of the inflorescence.     

Prospects and problems of irrigation development in Sahelian and sub-Saharan Africa

Although many different definitions of irrigation are being used, the need for this way of agricultural intensification is rapidly increasing as the population dependent on agriculture has in many countries largely surpassed the carrying capacity of rainfed systems. However, unfortunately many donor-sponsored irrigation projects in Africa disappoint because they are generally conceived with a too short time perspective and they suffer from a series of negative characteristics. Generally there is insufficient farmer involvement in all phases of the projects, which are formulated in isolation from existing farming systems, are capital-intensive and require high-input levels (from elsewhere), focus on the hardware, neglect agricultural production and institutional weaknesses, and cannot put up the money needed to be run. Therefore, sustainability should be the main point of orientation. Important steps towards it consist in choosing activities and forms of irrigation that fit well in the farming systems, are attractive to farmers, and can be run to a very large extent by themselves without external assistance. Marketing and production support services should be included in analysis and programmes of assistance, together with institutional strengthening and adequate land tenure arrangements. Governments' involvement in operation and management can often be reduced, and the same goes for the role of the irrigation organisations. Donor involvement should be more flexible, have a longer time-perspective, be less guided by expected economic rates of return and concentrate more on how to ensure increased sustainability of irrigation projects for both the country and the farmers.     

超排过程中不同发情时间对胚胎生产效果的影响

在牛胚胎生产过程中,由于不同牛只存在个体差异（如超排月龄、体重、营养状况、卵巢发育情况及初情期月龄等）,其对外界环境的适应能力存在不同的差异;目的：如何有效的控制好供体母牛同期发情的发情时间,提升超排后胚胎的质量与数量。方法：笔者选用10-16月龄的纯种肉用型西门塔尔牛进行胚胎生产,通过对112头次10-16月龄牛只超排进行胚胎生产并对相关数据进行统计分析;结果：根据认真观察记录供体牛只拆栓后的发情期表现,出现部分牛只提前发情或延迟发情现象,其中大部分牛只处于拆栓后24h前后两h集中发情情况;结论：供体母牛在拆栓后24h前后两h集中发情的牛只,其头均生产胚胎的数量与质量均优于延迟发情和提前发情的牛只。     

供体细胞的传代次数和不同处理方法对异种核移植效率的影响

实验旨在探讨供体细胞培养代数及其所处的细胞周期对异种核移植效率的影响.以经Hochest33342染色后去核的牛卵母细胞为受体,以处于不同细胞周期的不同代数的人成纤维细胞为供体,采用电融合方法构建重构胚,6-DAMP和乙醇激活重构胚,SOFaa培养液中培养.第20代细胞非饥饿组的融合率、发育率显著低于第20代饥饿组（P＜0.05）,极显著的低于第8代细胞的饥饿组和非饥饿组（P＜0.01）,而8-细胞胚胎率,囊胚率4组间无显著差异.结果表明,饥饿处理对于培养代数低的细胞来说可能是非必要因素,但对于高代次细胞则是提高核移植效率的必要步骤,饥饿处理可使核移植融合率和发育率显著的提高.     

供体细胞的不同处理及重组胚化学激活对体细胞克隆胚胎发育的影响综述

哺乳动物体细胞克隆经过几年的发展,已取得了很大进展。已有多种细胞被采用并得到了克隆后代。但动物克隆效率仍然很低,供体细胞的选择和重组胚激活是动物克隆中的重要步骤。供体细胞的细胞周期、细胞类型、冷冻处理和化学激活等方面都可能影响动物克隆的效率。