野生番茄单片段渐渗系的创建及应用

 野生种质的自然变异是植物育种和品种改良的重要遗传资源, 标记辅助单片段渐渗系的构建为野生资源优良等位基因的有效利用提供了新的工具。本文综述了野生番茄单片段渐渗系的创建及其在基因精细定位、QTL遗传效应分析以及图位克隆中的应用。     

FISH mapping of 10 canine BAC clones harbouring genes and microsatellites in the arctic fox and the Chinese raccoon dog genomes

Cytogenetic mapping of the arctic fox and the Chinese raccoon dog were performed using a set of canine probes derived from the Bacterial Artificial Chromosome (BAC) library. Altogether, 10 BAC clones containing sequences of selected genes (PAX3, HBB, ATP2A2, TECTA, PIT1, ABCA4, ESR2, TPH1, HTR2A, MAOA) and microsatellites were mapped by fluorescence in situ hybridization (FISH) experiments to chromosomes of the canids studied. At present, the cytogenetic map on the arctic fox and Chinese raccoon dog consists of 45 loci each. Chromosomal localization of the BAC clones was in agreement with data obtained by earlier independent comparative chromosome painting. However, two events of telomere‐to‐centromere inversions were tentatively identified while compared with assignments in the dog karyotype.     

Clinical usefulness of intradermal fluorescein and patent blue violet dyes for sentinel lymph node identification in dogs

The first lymph node receiving drainage from a specific anatomic region is referred to as the sentinel lymph node (SLN). This study sought to evaluate the intradermal use of two dyes, patent blue violet (PBV) and fluorescein (FL), for SLN mapping in the dog. Multiple intradermal injections were performed in five healthy dogs using two dyes, PBV in 0.9% NaCl and FL in solutions of 0.9% NaCl and 6% hetastarch. Skin flaps were raised and followed to the first area of discrete stain uptake. Areas of uptake were identified as lymph nodes grossly and by cytology. Identification of a SLN for each area of intradermal injection was accomplished for 98% of the injection sites. Intradermal injections of both PBV and FL dyes produce readily visible staining of lymphatic vessels and SLNs in healthy dogs and are sufficient to allow ready identification of these structures during postmortem dissection.     

Accounting for heterogeneity of variances to improve the precision of QTL mapping in dairy cattle

The principle of interval mapping for quantitative trait loci (QTL) was originally developed for the analysis of single backcross data but it has been increasingly applied to more complicated experimental designs and data structures. It is important to study whether accounting for the heterogeneity of variance would improve the precision of QTL mapping based on data of multiple populations or families. This study compared homogeneous and heterogeneous maximum likelihood approaches for QTL mapping. The data consisted of 433 sons from six sire families with 69 microsatellite markers distributed over 12 chromosomes. The results of this study indicate that the heterogeneous approach generally produced a smaller residual variance and thus provided a better fit to the data than the homogeneous approach, meaning that the heterogeneous approach offers better precision in estimating both positions and effects of QTL. The results further showed that accounting for the heterogeneity of residual variance led to different statistical inferences from ignoring the heterogeneity of variance in QTL mapping. The heterogeneous approach is useful for QTL mapping based on the joint data of diverse reference populations or heteroscedastic data obtained from crossing animals with different genetic backgrounds.     

技术创新——知识经济时代企业发展的战略选择

21世纪人类社会即将步入快速变化的知识经济时代。知识经济是以知识和信息为基础的经济,强调知识的重要作用。知识是推动经济增长和生产力发展的决定性因素,而技术创新相应成为影响竞争的关键因素。谁成为技术的领先者,谁就拥有了发展的主动性、优先权和竞争的决胜权。目前,技术创新还存在许多问题,既有认识上的,也有制度上的。但是不可否认的是,技术创新确实有着旺盛的生命力和美好的前景。面对激烈的竞争,进行技术创新已是刻不容缓的事情。     

浅谈高职专英语听力教学现状及对策

语言习得主要通过获得大量的可理解输入来实现，而听是获得可理解语言输入的最重要的渠道。本文通过英语听力教学的现状分析，探讨了英语教学中提高听力的方法和对策。     

肉食兽4种细小病毒亲缘关系的研究

首先应用血凝抑制试验(HI)和对流免疫电泳交叉试验,对从我国分离的貂肠炎病毒(MEV)、豹细小病毒(LPV)、犬细小病毒(CPV)和貉细小病毒(RPV)进行了血清学比较研究,发现这4种病毒在血清学上关系密切.然后从感染病毒48h的猫肾传代细胞中分别提取、纯化这4种病毒的中间复制型DNA(RF-DNA),以λ—DNA—Hind Ⅲ片段为分子量标记,确定4种病毒的RF—DNA分子大小均在5kb左右.再应用限制性内切酶Hac Ⅲ和Hind Ⅲ分别完全酶切4种病毒的RF—DNA.结果表明,应用Hind Ⅲ酶切,4种细小病毒的RF—DNA都产生3个酶解片段;应用Hac Ⅲ酶切,MEV产生3个酶解片段,其余3种病毒产生4个相同的酶解片段,从而可将MEV与其余3种病毒明显地区别开.Hac Ⅲ酶切MEV和CPV的结果与国外报道的“MEV产生5个片段,CPV产生6个片段”不同.     

大豆分枝数相关分子标记开发及qBN-18位点精细定位

The branch number is one of the important factors influencing soybean yield, which is directly related to pod setting rate. At the same time, it is also an important component of soybean plant type, and further affects the yield by adjusting the population structure and planting density. At present, there is few report related to map-based cloning of genes related to branch number. Therefore, the discovery of genes/QTL involved in the regulation of soybean branching is of great significance for the basic research on the establishment of plant type and the applied research on the development of high-yielding varieties. In this study, based on the F₂ of crossing low-branched variety Kenfeng 19 (KF19) and high-branched variety Kennong 24 (KN24), we developed the F_7:8 recombinant inbred line (RIL) population, consisting of 606 lines, and two backcrossing populations consisting of 1486 individuals for KF19-BC₃F₂ and 1150 individuals for KN24-BC₂F₂. Within the localization interval of the new QTL of the branch number of chromosome 18 (qBN-18), 11 polymorphism SSR markers were screened out to identify the RIL population, and region of qBN-18 was reduced from 1.6 Mb to 113 kb. After developing two InDel markers BR69 and BR77 in the mapping region, the backcross population was used to screen the exchange individuals, the interval of qBN-18 was further reduced to 63.7 kb, including 9 genes. Those results provide the information for gene map-based cloning and molecular marker assisted breeding of branch number in soybean.     

一个新的水稻脆秆突变体bc17的鉴定及基因定位

A brim culm mutant bc17 (brittle culm 17) was obtained by irradiating wyj7 (Wuyunjing 7) with heavy ions. The brittle traits of the mutant were only found in the stalks and not in the leaves. The brittleness of the culm began to appear after heading stage, while it became more obvious as rice grew from heading stage to maturity stage. The growth and development of the mutant were affected, the plant height of the mutant was significantly lower than that in the wild type, and tiller number and seed setting rate were also lower than in the wild type. Compared with wild type, the cellulose content in bc17 culms and leaves decreased by 22.7% and 18.67%, while the hemicellulose content increased by 45.76% and 31.36%, respectively. The breaking resistance and tensile force of bc17 were significantly lower than those of wild type, indicating that the mechanical strength of the culm changed. The thick-walled cells of bc17 culms had larger pores, looser structures, and fewer cells. The fragile characteristics of bc17 were controlled by a single recessive nuclear gene. The bc17 gene was located in the 162 kb region of chromosome 7 by map-based cloning. Bioinformatics analysis indicated that it might be a novel gene related to rice brittle culm. These findings provided an important material support for the research on the molecular mechanism of cell wall synthesis in rice.     

Fuzzy k-means classification of topo-climatic data as an aid to forest mapping in the Greater Yellowstone Area, USA

Previous attempts to quantify topographic controls on vegetation have often been frustrated by issues concerning the number of variables of interest and the tendency of classification methods to create discrete classes though species have overlapping property sets (niches). Methods of fuzzy k-means classification have been used to address class overlap in ecological and geographical data but previously their usefulness has been limited when data sets are large or include artefacts that may occur through the derivation of topo-climatic attributes from gridded digital elevation models. This paper presents ways to overcome these limitations using GIS, spatial sampling methods, fuzzy k-means classification, and statistical modelling of the derived stream topology. Using data from a ca. 3600 km² forested site in the Greater Yellowstone Area, we demonstrate the creation of meaningful, spatially coherent topo-climatic classes through a fuzzy k-means classification of topo-climatic data derived from 100 m gridded digital elevation models (DEMs); these classes were successfully extrapolated to adjacent areas covering a total of ca. 10000 km². Independently derived land cover data and middle infrared corrected Landsat TM derived estimates of Normalised Difference Vegetation Index (M_NDVI) at 575 independently sampled sites were used to evaluate the topo-climatic classes and test their extrapolation to the larger area. Relations between topo-climatic classes and land cover were tested by ² analysis which demonstrated strong associations between topo-climatic class and 11 of the 15 cover classes. Relations between M_NDVI and topo-climatic classes proved to be stronger than relations between M_NDVI and the independent cover classes. We conclude that the fuzzy k-means procedure yields sensible and stable topo-climatic classes that can be used for the rapid mapping of large areas. The value of these methods for quantifying topographic controls on biodiversity and the strength of their relations with computed NDVI values warrant further investigation.