华北地区小丛红景天种群的AFLP遗传多样性

利用扩增片段长度多态性(AFLP)标记, 对分布于华北地区5个山脉的25个小丛红景天(Rhodiola dumulosa)自然种群的776个样品进行了遗传多样性和遗传结构的研究。结果表明: 华北地区小丛红景天种群具有较高的遗传多样性, 4对选择扩增引物共扩增出398条清晰的条带, 其中多态带312条, 种群的平均多态位点百分率为78.46%, 种群总的Nei’s基因多样性为0.364 9, 总Shannon多态性信息指数为0.542 2。华北地区小丛红景天种群间的遗传分化系数G_st = 0.150 7, 基因流Nm = 2.817 9, 表明种群间遗传分化较低, 有一定的基因交流。AMOVA分析结果也表明: 华北地区小丛红景天的遗传变异主要存在于种群内, 地理单元间有一定的遗传分化, 而种群间的遗传分化较低。STRUCTURE的分析和UPGMA聚类分析结果一致, 结果显示地理分布距离相近的种群优先聚在一起。Mantel检验也进一步证实, 华北地区小丛红景天种群的遗传距离与地理距离间呈显著的正相关关系(r = 0.512 9, p < 0.001)。种群的遗传多样性与海拔呈显著的负相关关系(p < 0.05), 而与坡向没有显著相关性。用Dfdist软件分析海拔对遗传多样性的影响, 结果表明没有显著的受选择位点。     

Geographic pattern of genetic variation in the European globeflower Trollius europaeus L. (Ranunculaceae) inferred from amplified fragment length polymorphism markers

The distribution of genetic variation and the phylogenetic relationships between 18 populations of the arctic-alpine plant Trollius europaeus were analysed in three main regions (Alps, Pyrenees and Fennoscandia) by using dominant AFLP markers. Analysis of molecular variance revealed that most of the genetic variability was found within populations (64%), although variation among regions (17%) and among populations within regions (19%) was highly significant (P < 0.001). Accordingly, the global fixation index FST averaged over loci was high (0.39). The among-population differentiation indicates restricted gene flow, congruent with limited dispersal of specific globeflower's pollinating flies (Chiastocheta spp.). Within-population diversity levels were significantly higher in the Alps (mean Nei's expected heterozygosity HE = 0.229) than in the Pyrenees (HE= 0.197) or in Fennoscandia (HE = 0.158). This finding is congruent with the species-richness of the associated flies, which is maximum in the Alps. We discuss the processes involved in shaping observed patterns of genetic diversity within and among T. europaeus populations. Genetic drift is the major factor acting on the small Pyrenean populations at the southern edge of T. europaeus distribution, while large Fennoscandian populations result probably from a founder effect followed by demographic expansion. The Alpine populations represent moderately fragmented relics of large southern ancestral populations. The patterns of genetic variability observed in the host plant support the hypothesis of sympatric speciation in associated flies, rather than recurrent allopatric speciations.     

番茄抗青枯病基因的AFLP分子标记

用番茄高抗青枯病品种“T51A”与高感青枯病品种“T9230”配制杂交组合,接种鉴定其正反交Ｆ₁代及Ｆ₂代分离群体的青枯病发生情况。结果表明,T51A对青枯病的抗性属于细胞质遗传,受1对杂合基因加性控制。用64个EcoRＩ/ＭseＩ引物组合对“T51A”、“T9230”两个亲本及其Ｆ₂代抗病和感病基因池进行AFLP分析,共扩增出约4200条可分辨的带,其中2条为稳定的差异。用“T51A”和“T9230”杂交产生的Ｆ₂代分离群体对2个特异条带与目的基因的遗传连锁性进行分析,发现特异条带AAG/CAT与暂定名为RRS-342的抗青枯病基因紧密连锁,二者之间的遗传距离为6.7 cM。将AAG/CAT片段回收、克隆和测序,成功地将其转化为SCAR标记,可以更加方便地用于对番茄青枯病基因的标记辅助选择。     

Identifying insecticide resistance genes in mosquito by combining AFLP genome scans and 454 pyrosequencing

AFLP‐based genome scans are widely used to study the genetics of adaptation and to identify genomic regions potentially under selection. However, this approach usually fails to detect the actual genes or mutations targeted by selection owing to the difficulties of obtaining DNA sequences from AFLP fragments. Here, we combine classical AFLP outlier detection with 454 sequencing of AFLP fragments to obtain sequences from outlier loci. We applied this approach to the study of resistance to Bacillus thuringiensis israelensis (Bti) toxins in the dengue vector Aedes aegypti. A genome scan of Bti‐resistant and Bti‐susceptible A. aegypti laboratory strains was performed based on 432 AFLP markers. Fourteen outliers were detected using two different population genetic algorithms. Out of these, 11 were successfully sequenced. Three contained transposable elements (TEs) sequences, and the 10 outliers that could be mapped at a unique location in the reference genome were located on different supercontigs. One outlier was in the vicinity of a gene coding for an aminopeptidase potentially involved in Bti toxin‐binding. Patterns of sequence variability of this gene showed significant deviation from neutrality in the resistant strain but not in the susceptible strain, even after taking into account the known demographic history of the selected strain. This gene is a promising candidate for future functional analysis.     

Biologically based insecticides for the control of immature Australian mosquitoes: a review

Abstract  Our review outlines changes in insecticide usage for mosquito control against Australian mosquitoes, with a focus on biologically based insecticides. The most widely used microbial insecticide is Bacillus thuringiensis var. israelensis de Barjac ( Bti ) and it is regularly used in estuaries and freshwater. In comparison, the use of Bacillus sphaericus (Neide) is limited to freshwater. The only insect growth regulator registered for mosquito control in Australia is s -methoprene, and it is used in both estuaries and freshwater. Although biologically based insecticides have been used for more than 10 years, there remains knowledge gaps surrounding the use of specific formulations in specific habitats: for example, VectoBac WG ( Bti ) and VectoBac G ( Bti ) in containers containing freshwater, or Altosid pellets ( s -methoprene) in ground-pool freshwater habitats. Where broad-scale mosquito control programs have been implemented in Australia, a reduction in the incidence of mosquito-borne disease, mainly Ross River virus, has been recorded. Therefore, the future application of these products is supported. The use of insecticides should be integrated with public education, biological control, physical habitat modification and coupled with spatial risk assessment.     

AFLP-Based detection of DNA methylation

By using the isoschizomersHpa II andMsp I which display differential sensitivity to cytosine methylation, a modified amplified fragment length polymorphism (AFLP) technique has been developed to investigate DNA methylation profiles in eukaryotic organims. Genomic DNA was digested with a mixture ofEcoR I and one of the isoschizomers, and ligated to oligonucleotide adapters. After two rounds of selective PCR amplification, followed by DNA separation on a Long Ranger gel electrophoresis, a subset of restriction fragments can be displayed on an X-ray film. Comparison of AFLP banding patterns betweenHpa II andMsp I revealed the extent of DNA methylation. The technique has been successfully applied in this study to investigate DNA methylation profiles of apple (Malus domestica cv. Gala) genomic DNA extracted from leaves of field-grown adult trees andin vitro-grown shoot cultures. The results showed that up to 25 percent of AFLP bands were derived from methylated sequences, and among those, a few bands unique to either adult trees orin vitro shoots were observed. These results demonstrated that this protocol is effective in identifying methylated DNA profiles. Both first authors have contributed equally to this work.     

Isolation of Bacillus thuringiensis subsp. israelensis from diseased field-collected larvae of the saturniid moth, Hylesia metabus, in French Guiana

Abstract An isolate of Bacillus thuringiensis subsp. israelensis (BTI) was obtained from field-collected larvae of the saturniid moth, Hylesia metabus . This isolate was shown to belong to serotype H 14, and to produce a spherical parasporal body identical to that of the type strain of BTI. With an LC₅₀ of 0.764 μg cm⁻², this isolate was more toxic to H. metabus than the HD-1 strain of B. thuringiensis subsp. kurstaki (HD-1). These results demonstrate that BTI can be active against lepidopterous insects, a wider spectrum of activity than previously realized.     

基于果蝇DNA甲基化的AFLP体系的建立及优化

以黑腹果蝇(Drosophila melanogaster)Canton-S品系为材料,采用改良SDS法提取高质量DNA,对连接、预扩增及选择性扩增进行分析,建立适用于果蝇基因组DNA甲基化多态性研究的AFLP优化体系:1)10μL连接体系加T4连接酶1 U,AluⅠ接头50 pmol,EcoR Ⅰ接头5 pmol,4℃反应12 h;2)25μL预扩增体系含Mg2+0.2 mmol/L,dNTPs 0.15 mmol/L,模板1.0μL,Taq DNA聚合酶2 U,E-00 50 ng,A-00 50 ng;3)25μL选择性扩增体系含Mg2+0.1 mmol/L,dNTPs 0.15 mmol/L,模板2.0μL,Taq DNA酶1.5 U、E+340 ng,A+3 40 ng.该体系稳定性高、重复性好,适用于果蝇基因组DNA甲基化多态性研究.     

基于AFLP标记的野生梅种质的鉴定

梅Prunus mume是我国原产的名花佳果。为有效保护和利用野生种质资源,文中采用了AFLP标记技术,结合形态表型特征分析,对65份野梅种质进行试验分析。首先从64对引物中筛选出MseⅠ-EcoRⅠ8对引物组合,扩增出1 002条多态性条带。按照Nei’72距离系数进行聚类,在Nei’72=0.26处,可区分西山野梅原变种、西山野梅原种、西山毛梅、厚叶梅、南大坪桃梅、嵩明小梅、曲梗常绿梅、蜡叶梅以及匍匐梅,这与形态学上变种或变型的划分一致。群体内变种单株样本遗传多样性丰富。基于梅花种质资源的遗传变异,建议今后需要对所有变种与变型进行有效的保护。     

pms3 is the locus causing the original photoperiod-sensitive male sterility mutation of‘Nongken 58S'

Photoperiod-sensitive genic male sterile (PSGMS) rice is a very useful germplasm for hybrid rice development. It was first found as a spontaneous mutant in a japonica cultivar 'Nongken 58'. pms3 on chromosome 12 was determined to be the locus where the original PSGMS mutation occurred, changing the normal cultivar Nongken 58 to PSGMS Nongken 58S. Large amounts of RAPD and AFLP analyses were also conducted for the fine mapping of the pms3 genomic region, which resulted in 4 molecular markers linked to pms3. Although these markers somewhat increased the marker density of this region, the pms3 locus is still located in a marker-sparse region.     

A modified AFLP with fluorescence-labelled primers and automated DNA sequencer detection for efficient fingerprinting analysis in plants

A modified AFLP (amplified fragment length polymorphism) technique is described. Fluorescence-labelled primers were used in the selective amplifications. The amplified fragments were detected on denaturing polyacrylamide gels using an automated ALF DNA sequencer with the fragment option. The modified AFLP technique avoids the use of isotopes or silver staining, but gives a much higher resolution than other AFLP detection systems.     

Susceptibility of Field Populations of Anopheles sinensis (Diptera: Culicidae) to Bacillus thuringiensis subsp. israelensis

The susceptibility of Anopheles sinensis to Bacillus thuringiensis subsp. israelensis (Bti) was evaluated through exposure to varying concentrations of Bti. Mosquitoes were collected from five field populations of southern and central China (Zhongshan, Hengxian, Wuchang, Xinzhou, and Ruichang) and compared with a standard laboratory strain. The LC₅₀ values were 146.4, 50.4, 57.9, 50.0, 41.6 and 24.6 ng/mL, respectively. Differences in susceptibility to Bti ranging from 1.7 to 5.9-fold compared with the laboratory strain. The Zhongshan strain had the greatest resistance. At low doses, Bti displayed residual effects. Peak mortality occurred from the first to the fourth day. Exposure to low doses increased the duration of larval development and decreased the duration of pupal development, indicating that low doses of Bti have a sublethal effect on their hosts.     

Population decline despite high genetic diversity in the new allopolyploid species Senecio cambrensis (Asteraceae)

Senecio cambrensis (Welsh groundsel) is a new allohexaploid species, which originated in Wales, UK, in the early part of the 20th century following hybridization between the native tetraploid groundsel (Senecio vulgaris) and the introduced diploid Oxford ragwort (Senecio squalidus). A survey of the number of populations and flowering individuals per population of S. cambrensis in Wales was conducted at peak flowering time in June 2002, 2003 and 2004. The results show a dramatic decrease in both population number and population size of the species since the 1980s when the last population census was conducted. A survey of amplified fragment length polymorphism (AFLP) variation showed that this decline has occurred despite the fact that S. cambrensis contains a high level of genetic diversity with each individual screened possessing a unique multilocus phenotype. The level of variance within the species was similar to that found in one parent (S. vulgaris) and slightly greater than that among samples of the other parent (S. squalidus). Only a small proportion (5%) of AFLP diversity was partitioned among populations indicating a lack of population structure and possibly high levels of gene flow via seed dispersal in what is predominantly a selfing species. Senecio cambrensis showed closer similarity in AFLP phenotype to S. vulgaris than to S. squalidus. Possible causes of this and also the high level of AFLP diversity found in S. cambrensis are discussed. It is suggested that intergenomic recombination following occasional multivalent formation during meiosis in S. cambrensis is likely to be an important cause of both phenomena, although other causes are not ruled out.     

Bti的溶血特性及其在Bti制剂毒力检测中的应用

实验利用Bti(苏云金杆菌以色列亚种）对兔红细胞（RBC）的溶血特性,以A541特征光吸收对Bti毒蛋白溶液体积或其对数作回归分析。结果表明：二者具有良好的直线关系。相关系数r≥0．95。方差分析表明：不同梯度的Bti每蛋白溶液处理之间差异极显著,处理内各重复之间差异不显著,同一天内的重复检测没有显著差异。本又给出了Bti制剂毒力检测的参考程度,并就该程度应用于Bti毒力快速检测作了较为详尽的探讨。     

普通小麦Qz180中一个抗条锈病基因的分子作图(英文)

普通小麦(Triticum aestivum L.)材料Qz180具有良好的抗条锈病特性,经基因推导发现其含有一个优良的抗条锈病的基因,暂定名为YrQz。用Qz180与感病材料铭贤169和WL1分别杂交构建了两个F_2群体,用条中30号条锈菌小种对这两个群体进行的抗性测验表明,YrQz为显性单基因遗传。通过SSR和AFLP结合BSA的方法对这个基因进行了分子作图,结果鉴定出与YrQz连锁的2个SSR标记和2个AFLP标记。根据SSR标记的染色体位置,该基因被定位在2B染色体的长臂上,位于两个SSR位点Xgwm388和Xgwm526之间;两个AFLP标记P35M48(452)和P36M61(163)分别位于该基因的两侧,遗传距离分别为3.4cM和4.1cM。