Prospects for discriminating Zingiberaceae species in India using DNA barcodes

We evaluated nine plastid(matK, rbcL, rpoC1, rpoB,rpl36-rps8, ndhJ, trnL-F, trnH-psbA, accD) and two nuclear(ITS and ITS2) barcode loci in family Zingiberaceae by analyzing 60 accessions of 20 species belonging to seven genera from India.Bidirectional sequences were recovered for every plastid locus by direct sequencing of polymerase chain reaction(PCR)amplicons in all the accessions tested. However, only 35(58%)and 40 accessions(66%) yielded ITS and ITS2 sequences,respectively, by direct sequencing. In different bioinformatics analyses, matK and rbcL consistently resolved 15 species(75%)into monophyletic groups and five species into two paraphyletic groups. The 173 ITS sequences, including 138 cloned sequences from 23 accessions, discriminated only 12 species(60%), and the remaining species were entered into three paraphyletic groups. Phylogenetic and genealogic analyses of plastid and ITS sequences imply the possible occurrence of natural hybridizations in the evolutionary past in giving rise to species paraphyly and intragenomic ITS heterogeneity in the species tested. The results support using matK and rbcL loci for barcoding Zingiberaceae members and highlight the poor utility of ITS and the highly regarded ITS2 in barcoding this family, and also caution against proposing ITS loci for barcoding taxa based on limited sampling.     

Concentration dependency of nonequilibrium thermal dissociation curves in complex target samples

The nonequilibrium thermal dissociation (NTD) methodology has been proposed to provide a superior discrimination between specific and nonspecific hybridizations than the commonly used array techniques involving hybridization followed by a single stringent wash. Multiple studies have used this method on gel-pad, planar, and nylon membrane arrays to identify specific microbial targets in complex target mixtures. A recent physicochemical study revealed several problems, particularly when the method was used to examine complex target samples. In the present study, we investigated the effect of target concentration on NTD of complex target samples obtained from an anaerobic bioreactor. Our purpose was to experimentally demonstrate that variation in the concentrations of both specific and nonspecific targets determines the course of dissociation, which was not evaluated in initial microbiological studies. We also present an approach for analyzing the dissociation curves that is less error prone compared to those used in the previous studies. Our results show that: (i) a specific target in a mixture, at a certain concentration, may have a higher dissociation temperature/time than that of the same pure target, and (ii) the concentration dependence of the dissociation precludes usage of reference curves for identifying a target. Contrary to the previous studies, an explicit calibration is required, which makes the NTD approach impractical for high throughput analysis.     

KCl处理对百合柱头生理及结实的影响

以百合（Lilium）品种‘Pollyanna’为材料,研究了KCl处理对柱头中SOD、POD及CAT等3种保护酶活性、可溶性蛋白含量以及电阻率的影响。结果表明,处理后3种酶的活性均表现出不同程度的应激性升高,其中SOD活性在花开当天和花开1d显著升高,在蕾期与花开2d极显著升高;花开当天及花开1d的POD活性极显著升高;CAT活性在花开1d升高显著,花开2d及3d时升高极显著。柱头可溶性蛋白含量及电阻率无显著变化,表明KCl处理削弱了细胞膜的膜脂过氧化作用,延缓了柱头衰老,提高了授粉受精作用,且与结实率升高表现出一定相关性。     

酶的基因剂量效应及其对鱼类远缘杂交的影响

亲缘关系较远的杂种二倍体,酶的表达出现父本基因受抑制,双亲基因表达迟缓和母本基因提前表达三种类型的紊乱。由于双亲等位基因不亲和,各等位基因只调控产生1／2的基因产物,从而致使胚胎出现“双单倍体综合症”而在孵化期全部死亡。远缘杂交三倍体由于母本基因剂量加倍,一方面抑制了父本基因的表达,消除了不协调基因活动的干扰,另一方面母本基因产物趋于正常,代谢得以正常进行,杂种后代能成活并正常生长。     

红菜薹新型细胞质雄性不育系的转育研究

以新型甘蓝型油菜（Brassica napus L.）细胞质雄性不育系（Eru CMS）为不育源,通过远缘杂交结合回交的方法,并运用组织培养、单株选择、异地加代种植的手段成功地将该不育基因转育到了红菜薹上。经检测所得的红菜薹（Brassica campestris L.ssp.chinensis L.var.utilis Tsen et Lee.）不育系苗期遇低温叶片不黄化,不育性稳定,蜜腺正常,不育度和不育株率均为100%。     

Elucidation of the B-genome donor to Triticum turgidum by unique- and repeated-sequence DNA hybridizations

In vitro DNA:DNA hybridizations and hydroxyapatite thermal-elution chromatography were employed to identify the diploid Triticum species ancestral to the B genome of T. turgidum. Unique and repeated sequences from the various Triticum species were separated by hybridization and thermal elution on hydroxyapatite. Unique- and repeated-sequence fractions of labeled T. turgidum var. durum DNA were hybridized to the corresponding fractions of unlabeled DNAs of T. searsii, T. speltoides, T. longissimum, T. sharonensis, and T. bicorne. Thermal stability profiles were constructed to evaluate base-sequence complementarity between T. turgidum var. durum and the diploid Triticum species. The heteroduplex thermal stabilities indicated that, of the five species examined, T. searsii was the most closely related to the B genome of T. turgidum var. durum. The thermal stability profiles further indicated that the repeated DNA fractions from the Triticum species are more similar than the unique-sequence fractions. This indicates that all of the Triticum species are very closely related and, in all probability, have diverged from a single progenitor species.Published with the approval of the Director of the West Virginia Agricultural and Forestry Experiment Station as Scientific Paper No. 1931.     

鲌鲂F1、F2及其亲本肌间骨的比较分析

为研究新型鲌鲂杂交鱼的肌间骨,采用常规测量和解剖法对鲌鲂F1 (female Culter alburnus Basilewskymale Megalobrama amblycephala Yih)、鲌鲂F2 (self-crossing of F1 hybrid of female C. alburnusmale M. amblycephala)及其母本翘嘴鲌(C. alburnus)、父本团头鲂(M. amblycephala)肌间骨的数目、形态和分布进行统计分析,结果表明,翘嘴鲌肌间骨数目为134-139,平均为136.8根; 团头鲂的肌间骨数目为121-129,平均为124.2根; 鲌鲂F1肌间骨数目为129-134,平均为131.6根; 鲌鲂F2肌间骨数目为127-134,平均为130.1根; 鲌鲂F1、F2与翘嘴鲌、团头鲂之间肌间骨数目差异显著(P0.05); 鲌鲂F1每一肌节所含肌间骨数目最多,为0.8024; 鲌鲂F2最少,为0.7744; 翘嘴鲌和团头鲂介于鲌鲂F1和F2之间,分别为0.7953和0.7763。4种鱼均含有I形、卜形、Y形、一端多叉形、两端两分叉形、两端多叉形和树枝形7种类型肌间骨,髓弓小骨比脉弓小骨多且复杂; 鱼体左右两侧肌间骨的数目不完全相等,形态也不完全对称,但较为接近,且肌间骨越靠前端,形态越复杂; 研究获得的鲌鲂F1和F2在肌间骨总数、复杂型肌间骨数目和躯体轴下肌肌间骨数目均较母本有所减少,鲌鲂F2较F1还呈下降的趋势,且每一肌节所含肌间骨最少,表现出一种有利于提高食用品质和精深加工的优势。研究结果为鲌鲂属间远缘杂交培育少肌间骨新品种提供了基础资料。     

植物远缘杂交中的染色体行为及其遗传与进化意义

远缘杂交与多倍体化在高等植物的进化中起着重要的作用。但矛盾和令人费解的现象是“自然界在合成多倍体方面取得了巨大的成功,而人类在这方面却收效甚微”。其原因一方面可能是自然多倍体是长期自然选择和进化的产物,人类难以在短期内重复和完成这一过程;另一方面可能对不同的染色体组结合后的遗传与互作机制还不太了解。故多倍体化后的遗传和表观遗传成了目前多学科研究的重点。在有些有性和体细胞杂种内亲本染色体在细胞内分开排列,但此染色体行为的遗传和生物学意义还不太清楚。在植物远缘杂交中出现的假配生殖、半配生殖、染色体消除和亲本染色体组分开等异常染色体行为,也反映出不同物种在配子和染色体水平上的不亲和。需对植物远缘杂交中的染色体行为和遗传进行不同层次与系统的研究,才可能深入了解杂交后新种的形成及进化机制。