温度对GF43李离体保存中老化作用的影响

 研究了不同温度对GF₄₃李( ^{_{Prunus domestica}} L. ) 试管苗生长及老化过程的影响。结果表明在16 ℃保存条件下GF₄₃试管苗的营养生长缓慢, 8 ℃保存GF₄₃试管苗的营养生长极缓慢, SOD、CAT 和POD 等保护酶系统的活性维持较高水平, 体内O₂ 自由基、丙二醛(MDA) 含量较低, 细胞膜结构相对稳定, 从而延缓了试管苗的衰老, 延长了两次继代之间的时间, 对试管苗的保存十分有利。     

应用聚合酶链式反应鉴定新疆棉花落叶型黄萎病菌

用一对棉花落叶型黄萎病菌的特异性引物D1和D2进行PCR扩增,对于落叶型黄萎病菌,该对引物可特异性地扩增产生一段550bp的产物,而非落叶型黄萎病菌则不能被扩增.供试的35个新疆黄萎菌系中,有3个菌系扩增出550bp大小的落叶型黄萎病菌特异性片段,表明目前新疆已存在落叶型黄萎病菌,用此技术可快速、准确地检疫和鉴定落叶型黄萎病菌.     

桃树不同生长型及其研究进展

生长型是桃树重要的树体特征,是控制树体大小的遗传因素,与栽培关系密切。综合有关文献介绍了桃树的紧凑型、半矮化型、矮化型、柱型、直立型、短枝型、垂枝型等生长型资源及不同生长型在遗传、形态特征、生理、栽培等方面的研究进展。紧凑型受单位点显性基因控制,树体开张,分枝角度大,萌芽率及成枝力均高,光透过率较低;半矮化型树体介于普通型和紧凑型之间;矮化型为单基因隐性性状,节间极短,树体矮小,叶片密度大,光透过率低;柱型枝条分枝角度小,冠幅小,叶面积指数大;直立型介于柱型和普通型之间;短枝型能形成较多的短果枝,并以短果枝结果为主;垂枝型枝条披散下垂,枝条弯曲。不同生长型之间在氮素、干物质分配和内源激素水平上也存在一定的差异。紧凑型、矮化型由于树冠密度大,光透过率低而在应用上受到限制,直立型和柱型因适应了高密度栽培而更受人们的重视。针对目前存在的生长型分类与命名问题,作者认为应首先考虑节间长度,其次为萌芽率、成枝力等,然后考虑的是枝条的分枝角度。     

Functional heterogeneity in resources within landscapes and herbivore population dynamics

Large mammalian herbivores are notorious for their propensity towards population irruptions and crashes, yet many herbivore populations remain relatively stable. I explore how resource heterogeneity within landscapes dampens population instability, using a metaphysiological modelling approach considering patch state distributions. Resource heterogeneity is functionally stabilizing through spreading consumption away from preferred resources before these become critically depleted. Lower-quality resources act as a buffer against starvation during critical periods of the seasonal cycle. Enriching resource quality is destabilizing, even if patch diversity is maintained, because food quantity then becomes the limitation. The potential consequences of landscape fragmentation are explored using the Serengeti ecosystem, characterised by broadscale resource gradients, as a hypothetical example. Further insights provided by the model are illustrated with specific examples concerning the effects of patch scales and waterpoint distribution. A metaphysiological modelling approach enables the basic consequences of landscape heterogeneity to be distinguished from further effects that may arise from specific patch scales and configurations, without the distracting detail of spatially explicit models.     

噻二唑基-3-哒嗪酮类化合物的合成及生物活性

将取代的二酰基肼环合后,得到中间体2-芳基-5-氯甲基-1,3,4-噻二唑,然后与2-叔丁基-4-氯-5-羟基-3(2H)-哒嗪酮反应,合成了8个未见文献报道的含噻二唑基哒嗪酮类化合物,其化学结构经1H NMR、高分辩质谱和元素分析确认。生物活性测试结果表明,部分化合物对粘虫P.separate W.有较好的抑制生长活性,其中化合物 3b 的EC50值为21 mg/L。     

Validation of the specificity and sensitivity of species-specific primers that provide a reliable molecular diagnostic for <Emphasis Type="Italic">Xiphinema diversicaudatum</Emphasis>, <Emphasis Type="Italic">X. index</Emphasis> and <Emphasis Type="Italic">X. vuittenezi</Emphasis>

Xiphinema diversicaudatum and X. index are vector nematode species of economic importance in viticulture regions as they can transmit Arabis Mosaic, Grapevine Fanleaf and Strawberry Latent Ringspot viruses to grapevine. Wang et al. (2003) designed species-specific diagnostic primers from ribosomal genes for both these vector species as well as a vector and a non-vector species X. italiae and X. vuittenezi, respectively. Our study aimed to confirm the specificity and determine the sensitivity and reliability of the primers for the two vector species, X. diversicaudatumand X. indexwhen challenged with closely related longidorid species and general nematode communities typical of vineyard soil. With one exception, no PCR product was observed when the primers were tested against six Longidorus, one Paralongidorus and one Xiphinema non-target species. Occasionally (three out of eight replicate PCR reactions) a weak PCR product was noted when primers for X. index were tested with L. elongatus. Furthermore, when challenged with a range of non-target nematode species comprising the nematode community typical of viticulture soil, no PCR product was amplified. An experimental dilution series of extracted DNA rigorously demonstrated that DNA from an equivalent single specimen of the target virus-vector species, X. diversicaudatum and/or X. index, could be detected amongst 1000 equivalent non-targetX. vuittenezi. Also, extracted DNA from an equivalent single target specimen was detected when added to DNA extracted from the overall soil nematode community. The primers were assessed further by using serial mixtures of actual nematodes rather than extracted DNA to simulate field soil. Using this method, a single target nematode could be detected amongst 200 non-target specimens. Given their specificity, sensitivity and reliability, it appears that these diagnostic primers will be of great benefit to phytosanitary/quarantine services related to the viticulture industry.     

PRRS ELISA试剂盒检测猪繁殖与呼吸综合征病毒抗体的应用

利用重组杆状病毒表达的PRRSV核衣壳蛋白作抗原制成ELISA诊断试剂盒，检测人工感染PRRSV猪血清、疫苗免疫抗体和田间血清，并与IDEXX公司生产的试剂盒进行比较。结果表明，该试剂盒在PRRSV感染后8天内就可检出感染性抗体，而用IDEXX公司生产的试剂盒在感染后的18天才检测到感染性抗体，对弱毒疫苗的免疫检测也基本能反映出疫苗的免疫应答状况。对华东地区PRRSV流行病学调查结果表明，PRRSV在国内普遍存在，同时也证明研制的试剂盒，是客观科学调查我国PRRS流行情较理想的检测工具。     

两种一步法RNA提取试剂的比较

RNA的提取在生物医学研究和临床检测上应用广泛。本文分别用进口Invitrogen公司生产的以及我们自己研制的一步法RNA提取试剂，提取大肠杆菌RNA、鸡肌肉组织RNA和尿囊液RNA，通过核酸电泳和荧光定量RT-PCR进行比较。结果表明用我们自己研制的和进口的试剂提取的RNA都不含有DNA；这些RNA都可以作为模板进行RT-PCR检测，并且在数量上相互之间没有明显差异。说明我们自己研制的一步法RNA提取试剂可以取代进口试剂。此外，本文还讨论了此类试剂一些评定方法。     

牛初乳中活性物质IgG含量分析

通过对产犊后前四天内牛初乳活性物质(IgG)含量的检测，分析牛初乳中活性物质的变化规律及冻结、巴氏杀菌对其影响。     

微量元素氨基酸螯合物在养鸡生产中的应用

微量元素氨基酸螯合物是微量元素添加剂更新换代的优良产品,应用前景广阔。文章概述了微量元素氨基酸螯合物的营养特性、代谢机制、添加方式及其在养鸡生产中的应用。