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881.
To compare the pathogenicity of PPMV-1 in pigeons and chickens, both species of birds were experimentally infected with strain pi/CH/LHLJ/110822, which was isolated from a pigeon in China. The clinical signs, gross lesions, and histopathological changes were observed in pigeons inoculated with pi/CH/LHLJ/110822. The morbidity and mortality rates were 80% and 70% in pigeons, respectively, whereas there were no clinical signs or gross lesions in chickens inoculated with the same strain. The viral loads in tissue samples were detected by real-time RT-PCR, indicating that six tissue samples (i.e., kidney, lung, brain, trachea, Harderian glands, and proventriculus) had detectable viral RNA in all dead pigeons, and significant differences in viral loads between pigeons and chickens were observed in several tissue samples (i.e., Harderian glands, proventriculus, duodenum, pancreas, small intestine, and large intestine) on 3 days post-inoculation (dpi) and in brain tissue on 7 dpi. In general, viral loads in pigeons were higher than those in chickens, whereas antibody titers in pigeons were lower than those in chickens. These results showed differences in pathogenicity, efficiency of viral RNA replication, and humoral immunity, indicating different susceptibilities between the host species. Additionally, the cross hemagglutination inhibition assay and cross virus neutralization tests demonstrated that pi/CH/LHLJ/110822 antigenicity was different from those of strains La Sota and F48E9.  相似文献   
882.
Developing country livestock production systems are diverse and dynamic, and include those where existing indigenous breeds are currently optimal and likely to remain so, those where non‐indigenous breed types are already in common use, and systems that are changing, such as by intensification, where the introduction of new breed types represents significant opportunities. These include opportunities to improve the livelihood of the world's poor, increase food and nutrition security and enhance environmental sustainability. At present, very little research has focused on this issue, such that significant knowledge gaps in relation to breed‐change interventions remain. The purpose of this study is to raise awareness of this issue and suggests strategic research areas to begin filling these knowledge gaps. Such strategic research would include (i) assessing the impact of differing breed types in developing country livestock productions systems, from a range of viewpoints including intrahousehold livelihood benefit, food and nutrition security at different scales, and environmental sustainability; (ii) identification of specific livestock production systems within developing countries, and the type of livestock keepers within these system, that are most likely to benefit from new breed types; and (iii) identification of new breed types as candidates for in‐situ testing within these systems, such as through the use of spatial analysis to identify similar production environments combined with community acceptance studies. Results of these studies would primarily assist stakeholders in agriculture, including both policy makers and livestock keepers, to make informed decisions on the potential use of new breed types.  相似文献   
883.
Investigation of genetic structure on the basis of pedigree information requires indicators adapted to the specific context of the populations studied. On the basis of pedigree‐based estimates of diversity, we analysed genetic diversity, mating practices and gene flow among eight cat populations raised in France, five of them being single breeds and three consisting of breed groups with varieties that may interbreed. When computed on the basis of coancestry rate, effective population sizes ranged from 127 to 1406, while the contribution of founders from other breeds ranged from 0.7 to 16.4%. In the five breeds, FIS ranged between 0.96 and 1.83%, with this result being related to mating practices such as close inbreeding (on average 5% of individuals being inbred within two generations). Within the three groups of varieties studied, FIT ranged from 1.59 to 3%, while values were estimated between 0.04 and 0.91%, which was linked to various amounts of gene exchanges between subpopulations at the parental level. The results indicate that cat breeds constitute populations submitted to low selection intensity, contrasting with relatively high individual inbreeding level caused by close inbreeding practices.  相似文献   
884.
猪α-干扰素表达系统及其应用的研究进展   总被引:1,自引:1,他引:0  
就猪α-干扰素的分子特征、生物学特性、表达系统和猪基因工程α-干扰素的应用进行综述,以期为猪α-干扰素在广谱抗病毒活性、抗肿瘤以及免疫调节的临床应用提供参考。  相似文献   
885.
就气单胞菌外膜蛋白的基因工程亚单位疫苗、DNA疫苗、重组活载体疫苗等基因工程疫苗的研究现状、免疫方式以及不足之处进行了综述,以期为气单胞菌疫苗研制提供参考。  相似文献   
886.
采用淀粉凝胶电泳方法,对由日本海溯河洄游到中国境内绥芬河的三块鱼(Tribolodonbrandti)和珠星三块鱼(Tribolodon hakonensis)繁殖群体的生化遗传结构及变异进行比较研究。结果表明,在选取的12种同工酶中共检测出27个基因位点,三块鱼和珠星三块鱼的多态位点比例分别为22.22%和18.52%,平均杂合度分别为0.0670和0.0695;除了三块鱼的Gpi-1和珠星三块鱼的Est多态位点外,两种鱼的Ldh—1、α—Gpd-1、Sdh—1、Aat—1及三块鱼的Est多态位点上的基因型分布都显著地偏离Hardy—Weinberg平衡,表现出杂合子明显缺失或过剩现象;三块鱼和珠星三块鱼种群间相同基因位点上的等位基因分布频率出现显著的分化,遗传相似度和遗传距离分别为0.6912和0.3693。结论认为,三块鱼和珠星三块鱼的遗传多样性已达到种的差异水平。  相似文献   
887.
Siberian Pine (Pinus sibirica) is an ecologically and eco-nomically important species in pristine forests throughout northern Rus-sia. Four provenances of P. sibirica were introduced from Mongolia and Russia to the Greater Xing’an Range (the Daxing’anling), northeast China in 1993. The aim of this research was to study genetic variation and selection of the introduced four Pinus sibirica provenances. Heights (H), basal diameters (BD), survival rates (SR) and crown lengths (CL) of different families were measured as primary outcomes in different growth years. Results of data analyses demonstrated high coefficients of phenotypic variation (PCV) and heritability (H2) for H, BD and CL at 18 years after introduction. PCV and H2 increased with age. Correlations of growth traits between any two growth years were all significantly positive, but the correlation coefficient was smaller when the growth year interval was larger. Correlations between H and the original environment factors decreased gradually, indicating that with long-term subsistence in the new environment, the influence of the source environment declined. Colligation of multiple traits to estimate provenances showed that Novosibirsk, Tomsk, and Altai Mountains had higher survival rates and biomass, and proved more suitable for introduction and plantation in the Greater Xing’an Range in China.  相似文献   
888.
淮山药种质资源主要农艺性状遗传多样性分析   总被引:2,自引:0,他引:2  
【目的】探讨我国不同地区淮山药种质资源农艺性状的遗传多样性、亲缘关系及分类特征,为淮山药品种选育及生产利用提供参考。【方法】对收集的44份淮山药种质资源的19个农艺性状进行调查,通过遗传多样性分析、聚类分析与主成分分析,探讨其遗传多样性、亲缘关系及分类特征。【结果】44份淮山药种质资源形态性状间具有较高的多样性。在12个质量性状中,遗传多样性指数最高的是叶形(1.53),其次是薯皮颜色(1.51);薯形的频率分布最高(93.18%),其次为薯肉颜色(90.91%)和茎蔓形状(81.82%)。在7个数量性状中,多样性指数最高的是薯块长度(1.89),其次是生育期(1.84)和薯块径粗(1.77);变异系数最大的是单株产量(79.25%),其次为薯块径粗(42.21%)和单株结薯数(35.62%),最小的为生育期(17.57%)。根据各农艺性状的遗传差异,可将44份淮山药种质聚为四大类群;第Ⅰ类群种质均来源于广西,可作为有增产潜力的加工型亲本材料;第Ⅱ类群种质主要来源于广西,可作为高产选育目标亲本;第Ⅲ类群种质主要来自南方地区,均是人工栽培的野生类型品种,为一般性亲本;第Ⅳ类群种质主要来源于北方省区的种质,可作为一般性早熟选育亲本。主成分分析结果表明,前6个主成分累计贡献率达83.73%,第一主成分反映高产株型综合因子,第二主成分反映加工株型因子,第三主成分反映植株结薯因子,第四、五、六主成分分别反映薯块、薯皮颜色和茎蔓颜色因子。【结论】我国淮山药主要地方栽培种质资源间农艺性状差异明显,具有丰富的遗传多样性,其亲缘关系呈现一定地域生态环境规律;南方地区在品种选育中应注重对第一、第二主成分的选择。  相似文献   
889.
【目的】了解西林水牛群体的遗传变异和遗传结构,为其辅助标记育种、遗传资源保护及利用提供参考依据。【方法】从广西西林县的8个乡(镇)采集184份西林水牛血样,采用优化后的RAPD技术检测其多态性DNA,统计多态性条带数,并应用Popgene32软件对西林水牛群体的有效等位基因数、Nei氏基因多样性指数及Shannon多样性指数进行分析。【结果】从18条RAPD引物中筛选出8条扩增产物稳定、条带清晰可辨的引物,扩增出的DNA片段分子量为100-1000 bp;从184个样本中共扩增出4968个多态性条带,平均每条引物可扩增出621个多态性条带,多态性频率达60.0%-100.0%,平均为89.7%。西林水牛群体的平均有效等位基因数为1.6745,平均Nei氏基因多样度指数为0.3583,平均Shannon多样性指数为0.5510。【结论】西林水牛群体的遗传变异、遗传分化及遗传多样性均较高,但选育程度较低,育种潜力较大,有待进一步保种和开发利用。  相似文献   
890.
对23份油菜叶片的抗氧化酶活性(SOD、CAT和POD)和丙二醛质量摩尔浓度(MDA)进行测定,用聚丙烯酰胺凝胶电泳法分析其过氧化物酶同工酶,明确酶谱的特征及分布,并用聚类分析的方法分析各品种间的亲缘关系。结果表明,在温和的环境中,白菜型油菜相比甘蓝型油菜有更高的抗氧化酶活性和更低的脂质过氧化水平,说明白菜型油菜的抗逆性强于甘蓝型油菜,特别是白菜型油菜的过氧化物酶活性平均值比甘蓝型油菜的10倍还高。POD同工酶分析共发现67条酶带,白菜型和甘蓝型油菜都存在其特征谱带,不同品种在带型分布及显色强度上存在差异。白菜型油菜Largo、Prisma-B和Prisma-Y的p4酶带和甘蓝型油菜类似,表明这3个材料和甘蓝型油菜有较近的亲缘关系。聚类分析表明,在类平均距离4.98处可将23份油菜分为2大类:白菜型油菜和甘蓝型油菜;在类平均距离1.32处,可进一步分为4类。  相似文献   
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