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91.
退化梯度对克氏针茅种群遗传分化的影响 总被引:7,自引:1,他引:7
对重度退化、轻度退化和正常样地的克氏针茅种群进行RAPD研究。结果表明,3个种群扩增条带总数、多态位点比率、种群内稀有位点数、遗传多样性和基因多样性均是正常种群>轻度退化种群>重度退化种群。用Shannon指数估算3个种群的遗传多样性,其中72.39%的遗传变异存在于种群内,26.89%存在于种群间。重度退化与轻度退化种群,重度退化与正常种群间的遗传相似系数分别为0.8993和0.8159。在重度退化情况下克氏针茅种群遗传结构发生了一定的遗传分化。 相似文献
92.
Ghada Baraket Ahmed Ben Abdelkrim Olfa Saddoud Khaled Chatti Messaoud Mars Mokhtar Trifi Amel Salhi-Hannachi 《Scientia Horticulturae》2010
The trnL (UAA) intron and the intergenic spacer between the 3′ exon of trnL (UAA) and trnF (GAA) sequences were used as genetic markers for differentiating Ficus carica cultivars and establishing refined genetic relationships. The study was based on 20 fig cultivars, collected from south and centre of Tunisia. Since, the intron was thought to be more variable among close relatives than is the chloroplast spacer. The size of these non-coding regions varied from 554 to 589 and from 989 to 1022 bases pairs for the intron and the combined sequences correspondingly. The average of GC content was 33.9% and 34.6% in the intron and the combined intron and spacer respectively. High values of A + T contents were detected in both data sets and may explain the high proportions of transversions founded. The observed variation pattern of plastid DNA provides evidence of an important genetic diversity. The overall transition/transversion bias (R) was 0.202 in the intron and 0.27 in the combined regions. The RI index of 0.592 indicates that these combined sequences have clearly more homoplasy then the intron (RI = 0.705) and spacer (RI = 0.777) sequences separately. Phylogenetic trees were generated based on maximum parsimony (MP) and neighbor-joining (NJ) analysis of the chloroplast sequences data. Results proved that a typically continuous genetic diversity characterizes the local fig germplasm. In fact, relationships inferred from the cpDNA analysis suggest several clades, which do not show geographical or tree sex correspondence. Although the level of apparent diversity is considerable, we may conclude that non-coding regions of chloroplast genome provide a new and practical opportunity to evaluate genetic diversity and to discriminate fig cultivars. Revealed cytoplasmic DNA markers are reliable to elaborate a molecular data base to conduct management and breeding programs on local fig germplasm. 相似文献
93.
Ragnhild J Bager Egle Kudirkiene Isabelle da Piedade Torsten Seemann Tine K Nielsen Susanne E Pors Andreas H Mattsson John D Boyce Ben Adler Anders M Bojesen 《Veterinary research》2014,45(1)
The Gram-negative bacterium Gallibacterium anatis is a major cause of salpingitis and peritonitis in commercial egg-layers, leading to reduced egg production and increased mortality. Unfortunately, widespread multidrug resistance and antigenic diversity makes it difficult to control infections and novel prevention strategies are urgently needed. In this study, a pan-genomic reverse vaccinology (RV) approach was used to identify potential vaccine candidates. Firstly, the genomes of 10 selected Gallibacterium strains were analyzed and proteins selected on the following criteria; predicted surface-exposure or secretion, none or one transmembrane helix (TMH), and presence in six or more of the 10 genomes. In total, 42 proteins were selected. The genes encoding 27 of these proteins were successfully cloned in Escherichia coli and the proteins expressed and purified. To reduce the number of vaccine candidates for in vivo testing, each of the purified recombinant proteins was screened by ELISA for their ability to elicit a significant serological response with serum from chickens that had been infected with G. anatis. Additionally, an in silico prediction of the protective potential was carried out based on a protein property prediction method. Of the 27 proteins, two novel putative immunogens were identified; Gab_1309 and Gab_2312. Moreover, three previously characterized virulence factors; GtxA, FlfA and Gab_2156, were identified. Thus, by combining the pan-genomic RV approach with subsequent in vitro and in silico screening, we have narrowed down the pan-proteome of G. anatis to five vaccine candidates. Importantly, preliminary immunization trials indicated an in vivo protective potential of GtxA-N, FlfA and Gab_1309.
Electronic supplementary material
The online version of this article (doi:10.1186/s13567-014-0080-0) contains supplementary material, which is available to authorized users. 相似文献94.
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96.
植保环节是种植业产生环境污染和农产品质量安全风险的重要来源,水果是我国种植业的重要组成部分,果园植保高投入的特点使之成为制约种植业绿色发展的瓶颈。我国的水果生产以小农户为主,果园用药普遍存在不合理、不科学的问题,对其用药的管控难以有效实现。基于对主产区300余个苹果种植户的调查访问,首先回顾了我国苹果生产的发展历程和特点,分析了苹果生产中存在的问题,提出了小农户常规栽培管理是造成果园环境污染和水果质量安全隐患的主要原因的观点;其次从社会需要、农户需求、农户意愿3个层面分析了我国小农户苹果生产的植保托管需要,指出了构建果园植保托管体系的必要性;最后从我国水果产业绿色发展的视角,针对政府、服务者、农户3个行为主体提出了建议。 相似文献
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98.
试验旨在建立牛奶中6种玉米赤霉烯酮类霉菌毒素残留的超高效液相―串联质谱检测方法。牛奶样品经乙腈提取,免疫亲和柱净化,C18色谱柱分离,以0.02%(V/V)乙酸―水/甲醇为流动相,采用梯度洗脱方式进行液相色谱分离,多反应监测模式,外标法进行定量。牛奶中6种玉米赤霉烯酮类霉菌毒素的检测限可达到1.0 μg/L,且在2.5~100.0 μg/L的浓度范围内,线性关系良好。该方法专属性强、灵敏度高、分离度好,适用于牛奶中的6种玉米赤霉烯酮类霉菌毒素残留的测定。 相似文献
99.
白木香茎中内源茉莉酸类和倍半萜类物质对机械伤害的响应 总被引:2,自引:0,他引:2
为揭示伤害信号--茉莉酸类(JAs)对倍半萜可能的调控作用,以3年生白木香[Aquilaria sinensis(Lour.)Gilg]树苗为试材进行机械伤害和外施茉莉酸甲酯(MeJA)处理,测定其茎中内源JAs和倍半萜含量。结果表明,机械伤害处理1 h后,内源JAs含量显著增加,随后迅速下降;伤害处理24 h后又有小幅升高。伤害处理诱导白木香产生3种倍半萜(δ–愈创木烯、α–愈创木烯和α–葎草烯)且含量随着伤害时间延长而增多。外源MeJA处理也能够诱导产生相同种类的倍半萜且诱导强度大于伤害处理。伤害早期(1 h)内源JAs含量升高和伤害后期(48 h)倍半萜含量增多是植物启动相应的防御反应和抵御伤害胁迫的重要机制。 相似文献
100.
测定了青海省三江源地区土壤有机质与砷含量,并采用普通克里格插值方法研究其空间分布特征,结果显示:三江源地区土壤有机质含量多分布于3.0%~6.0%之间,约占样本总数的68%,超过7%的样品比例约为4%;土壤砷含量主要集中在0~10mg/kg之间,约占样本总数的50%,含量超过30mg/kg的样品比例为20%。土壤有机质含量与海拔之间存在显著负相关(r=-0.346,P<0.05),线性拟合方程为y=-0.042x+4.87(R2=0.11,P<0.05);土壤砷含量与海拔、土壤有机质含量之间均没有显著相关性。土壤有机质含量的块金效应为43.98%,存在中等程度的空间自相关关系;土壤砷含量的空间相关性强,块金效应为23.94%。土壤有机质和砷含量在大尺度上都存在比较明显的空间分布特征。 相似文献