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1.
云南光叶桑、钦州长果桑在形态分类学上均属同一桑种Morus macroura。通过PCR扩增2份地方品种资源材料的ITS序列并分析序列差异及构建系统进化树,阐明各自在桑属中的遗传分化关系。2份材料的ITS序列长度均为576 bp,其中:云南光叶桑的G+C含量为59.90%,碱基序列45位A变G,560位T变G,与昆明奶桑(Morus macroura)、荥经川桑(Morus notabilis)、云南毛叶奶桑(Morus macroura var.mawa)、云南长穗桑(Morus wittiorum)、云南奶桑(Morus macroura)、雅安华桑(Morus cathayana)同在第Ⅰ类群,有较近的亲缘关系;钦州长果桑的G+C含量为59.72%,碱基序列45位为A,560位T变G,与云南华桑(Morus cathayana)同在第Ⅱ类群,有较近的亲缘关系。应用松散分子钟方法估算云南光叶桑与荥经川桑、雅安华桑、云南长穗桑的分化时间为8.23 Ma,钦州长果桑与云南华桑的分化时间为9.67 Ma,二者起源的地质年代是新第三纪中新世与上新世之交,是为了抵御地球寒冷、旱化,向南、向山地迁移形成的物种。 相似文献
2.
在分析自流平混凝土特点的基础上,根据试验数据总结出自流平混凝土中不同的粉煤灰掺量对自流平混凝土性能的影响规律。在研制过程中系统分析了流动度L与扩展度D之间的关系,建立了L-D对比曲线,形象直观地表达了砂浆的使用性和工作性,最终选出较合理的掺量范围。 相似文献
3.
Summary Genetic divergence in 110 population (20 parents and 90 F1 hybrids) of opium poppy was studied by multivariate analysis. All the entries were grouped in 14 clusters. Out of 20 parents,
ten were accumulated in one cluster and rest 10 distributed over seven clusters. Estimates of cluster distance showed that
maximum intra-cluster distance was in -cluster IX (25.62) followed by cluster I (22.41), V (22.23) and IV (21.06). The inter
cluster distances varied from 16.62 (between cluster XII and XIV) to 195.10 (between cluster IV and IX). The cluster analysis
indicated substantial diversity among the parental genotypes, which had the potential to release considerable variation in
their crosses. The first four principal components (PCs) with eigen values >1 accounted for 68% of variation among the population.
The first and second components could account for 29 and 20% of the total morphological and alkaloidal variations, respectively.
The PC1 was closely related to yield and yield related traits. The characters contributing greatest positive weight on PC1
were opium yield, plant height, stem diameter, capsule weight/plant and seed yield/plant. The possibilities of relationship
between genetic divergence, F1 performance, heterosis and GCA of parents have been explored. 相似文献
4.
Sykes JE Drazenovich NL Ball LM Leutenegger CM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(4):685-693
BACKGROUND: The goals of this study were to develop and apply conventional (c) and real-time TaqMan polymerase chain reaction (PCR) assays for Mycoplasma haemofelis (Mhf), 'Candidatus Mycoplasma haematoparvum' (Mhp), and 'Candidatus Mycoplasma haemominutum' (Mhm) to blood samples of cats to determine the epidemiology of these infections in cats. HYPOTHESIS: Cats are infected with >2 hemoplasma species, and organism load correlates with disease induced by these organisms. ANIMALS: Blood samples from 263 anemic and nonanemic cats were used. METHODS: A retrospective study was conducted. RESULTS: Forty-seven (18%) samples were positive. Three samples (1%) yielded 170 base pair cPCR products, 1 of which was positive for Mhf using real-time PCR. Forty-four samples (17%) yielded 193 base pair cPCR products, 40 of which were positive for Mhm using real-time PCR. Organism loads ranged from 375 X 10(6)/mL to 6.9 x 10(6)/mL of blood. Sequencing of cPCR products from samples testing negative using real-time PCR identified 2 Mhp-like sequences, 1 Mhm-like sequence, and 1 sequence resembling 'Candidatus Mycoplasma turicensis'. Cats infected with Mhm were less likely to be anemic than uninfected cats. Older age, outdoor exposure, feline immunodeficiency virus (FIV) seropositivity, cutaneous squamous cell carcinoma (SCC), and stomatitis were associated with Mhm infection. Cats from the Sacramento Valley were more often infected with Mhm than cats from the San Francisco bay area. CONCLUSIONS AND CLINICAL IMPORTANCE: Cats may be infected with 4 hemoplasma species. The association between Mhm infection, FIV, and SCC may reflect outdoor roaming status of infected cats. The clustered distribution of infection suggests an arthropod vector in transmission. 相似文献
5.
利用NCEP/NCAR再分析资料,研究在台风"麦德姆"登陆北上过程中对其产生重要影响的高空槽的位置、强度、槽上暖中心的变化,且对槽进行了涡度方程的诊断分析。结果表明,高空槽向东移动的过程中有暖中心与之配合,致使高空槽强度不断增加。散度项、平流项和地转平流项对涡度的局地变化贡献较大,主要的正贡献来源于散度项。高空槽达到最强时,"麦德姆"低压环流和高空槽结合,受高空槽前部显著辐散场的影响,台风高层辐散、中心附近上升运动明显增强,这是台风"麦德姆"登陆后期强度得以维持的重要因素。 相似文献
6.
取星点笛鲷(白星笛鲷LutjanusstellatusAkuzaki)和千年笛鲷(L.sebaeCuvieretValenci-ennes)肝脏组织,分离纯化其线粒体DNA(mtDNA),用限制性内切酶分析构建了两个种mtDNA的物理图谱,进行了限制性片段长度多态性分析,得到两个种的分歧时间大约为5.1Ma(取序列进化率为每百万年1.5%),发现4种内切酶(BglⅠ、MluⅠ、KpnⅠ、SalⅠ)酶切位点在两种间存在明显差异。这些差异为区分两个种提供了遗传标记,同时也为笛鲷类进化遗传学的研究和育种提供了资料。 相似文献
7.
Guanghua Wang Motoki Hayashi Kazunari Tsuchiya Makoto Kimura 《Soil biology & biochemistry》2009,41(1):13-20
Many studies have shown the ecological importance of viruses as the greatest genomic reservoirs on the planet. As bacteriophages (phages) comprise the majority of viruses in the environment, we surveyed the capsid genes (g23) of T4-type phages, Myoviridae, from DNA extracts of three paddy field soils located in northern, central and southern Japan using the degenerate primers MZIA1bis and MZIA6. Denaturing gradient gel electrophoresis (DGGE) was performed to separate PCR-amplified g23 products, and 56 DGGE bands were identified as g23 fragments. Only nine clones were grouped into T-evens, PseudoT-evens and ExoT-evens, and most of the other clones were classified into Paddy Groups I-VI. No significantly different distribution of g23 clones was observed among the paddy fields at the group level, indicating that phage communities estimated from the g23 composition were common on the nationwide level. Comparison of g23 sequences showed that g23 genes in paddy fields were different from those in marine environments, and more divergence of g23 genes was estimated in the paddy fields compared to the marine environment. Two novel g23 clones with very short amino acid residues were detected, suggesting the existence of uncharacterized, novel groups of g23 genes in paddy field soils. 相似文献
8.
Results from a 2002 survey of Nevada ranchers that asked about willingness to pay for public forage and willingness to accept compensation to part with grazing rights provide empirical support for the contention of large divergence between WTA and WTP. WTA and WTP are estimated simultaneously, thereby enabling the identification of ranch characteristics that could explain the discrepancy in valuations. We find that some of the discrepancy might be explained by the size of a ranch's herd and the amount of public forage the ranch can access. We find little evidence that the ranching lifestyle accounts for the difference between WTP and WTA for public forage, as asserted by some ranch economists. It would appear that the discrepancy between WTA and WTP can be attributed primarily to an endowment effect. 相似文献
9.
无压渗漏计(Zero-tension lysimeter,ZTL)多用于非饱和带土壤溶质通量的监测,但由于ZTL安装时与原状土壤相接触会存在毛管障碍界面,易形成分散流使其土壤溶液收集效率降低。为准确描述田间水分渗漏量或土壤溶质的运移过程与规律,基于HYDRUS模型模拟结果,对ZTL不同设计(加装不同高度分散流控制壁)和不同适用环境条件(土壤质地、灌水量、土壤蒸发量和初始土壤含水率)的土壤渗漏水收集效率及影响因素进行数值模拟和定量评价。结果表明,无分散流控制壁的ZTL(ZTL0),在0.35 cm3/cm3土壤初始含水率、0.2 cm/d蒸发量和1 000 mm灌水量条件下的砂壤土、壤土和粉土处理,收集效率分别仅为11%、13%和26%,而在相同环境条件下安装分散流控制壁的ZTL(ZTLd),当控制壁高度为20 cm时可使收集效率提升到50%以上。安装的分散流控制壁高度随灌水量的降低、土壤持水能力的提高和土壤蒸发量的增大而升高,初始土壤含水率降低会使偏砂性土壤中安装的ZTLd收集效率降低,但在壤土和粉土中安装时可使其收集效率增大。增加ZTLd安装深度可能会导致其收集效率降低,在某一特定安装深度对ZTL收集效率计算的结果并不适用于其他深度。 相似文献
10.