澳洲坚果SCoT反应体系的建立及应用

为建立澳洲坚果(Macadamia spp.)的SCoT最适反应体系,用单因素设计方法对影响SCoT-PCR反应体系的主要影响因素进行了优化筛选,并构建了澳洲坚果种质的指纹图谱。结果表明,澳洲坚果的SCoT最适反应体系为:反应体系总体积为20μL,包含2.5 mmol L–1Mg2+,0.3 mmol L–1dNTPs,0.8μmol L–1引物,40 mg L–1模板DNA和1.0 U Taq DNA聚合酶。最适退火温度为50℃。该反应体系对澳洲坚果种质具有良好的稳定性、可靠性和较高的分辨率。选用多态性良好的单引物SC5和引物组合SC34+SC39,可以将12份澳洲坚果种质完全区分开,每份种质都各有独特的指纹图谱,置信概率达到99.988%。构建的SCoT反应体系可为澳洲坚果种质鉴定和遗传多样性分析等提供技术支持。     

番木瓜SCoT反应体系建立及引物筛选

采用单因素试验方法对番木瓜(Carica papaya L.) SCoT-PCR反应体系进行了优化,并对引物进行了筛选。结果表明,在20 μL番木瓜SCoT-PCR反应体系中,包含2.0 mmol/L Mg2+,0.3 mmol/L dNTPs,0.8 μmol/L引物,30 mg L-1模板DNA和1.0 U Taq聚合酶。运用该体系对不同引物和22个番木瓜品种进行验证,扩增的稳定性、可靠性良好,且分辨率较高,同时筛选出多态性丰富的5条引物和5对引物组合。因此,优化的番木瓜SCoT-PCR反应体系可用于种质鉴定和遗传多样性分析。     

龙眼SCoT-PCR反应体系的优化

目标起始密码子多态(start condon tardeted polymorphism,SCoT)分子标记结合了ISSR标记和RAPD标记的优点,具有操作简单、成本低廉、多态性丰富、重复性好、引物设计简单且通用性良好等诸多优点.本实验以石硖龙眼的新鲜叶片为试材,采用单因素试验的方法分别研究模版、引物、rTaqDNA聚合酶、dNTPs、缓冲液(Mg~(2+))及退火温度共6因素各8个水平对龙眼SCoT-PCR扩增结果的影响.结果表明:龙眼SCoT标记的20μL优化反应体系为:10×Buffer Ⅱ(含Mg~(2+))2.0μL、DNA模板30 ng、引物浓度为30 μmol/L、rTaqDNA聚合酶用量为0.45 U、dNTP浓度为4.0 mmol/L.适宜的扩增程序为:94℃预变性4 min;95℃变性50 s,49.5℃退火40 s,72℃复性2 min,36个循环;最后72℃延伸10 min.利用24个龙眼品种验证该反应体系,1.5%琼脂糖电泳检测结果显示,扩增产物在400～2 200 bp之间,不同品种间DNA谱带具有多态性,反应体系具有良好的稳定性和可重复性.     

新疆枸杞种质资源遗传多样性分析及DNA指纹图谱构建

利用SCoT分子标记对新疆枸杞种质资源进行遗传多样性分析和DNA指纹图谱构建,为杂交育种和种质鉴定提供理论依据。结果显示:9条SCoT引物扩增出条带256条,其中219条为多态性条带,多态性比率达85.62%,多态性信息含量(PIC)值变化范围在0.77~0.91之间,平均值为0.85,观测等位基因数(Na)、有效等位基因数(Ne)、Nei's基因多样性指数(H)和Shannon信息指数(I)的平均值分别为1.8562、1.4350、0.2611、0.3989,聚类分析表明,遗传相似系数变化范围在0.5938~0.8398之间,在遗传相似系数为0.66和0.71处,可将30份材料分别分为2大类和4个亚类,主坐标分析结果和聚类结果基本一致,同时利用5条多态性SCoT引物构建了30份材料的DNA指纹图谱。新疆枸杞种质资源遗传多样性水平较高,且SCoT分子标记适于新疆枸杞种质资源遗传多样性分析和DNA指纹图谱构建,该研究结果为新疆枸杞种质资源评价、鉴定和新品种选育奠定了基础。     

正交设计优化绿竹ISSR-PCR体系和引物筛选

旨在建立绿竹ISSR-PCR最佳反应体系和扩增程序,并筛选适于绿竹ISSR-PCR分析的高多态性引物。以绿竹基因组DNA为ISSR-PCR扩增模板,采用正交试验方法,对d NTPs浓度、Mg2+浓度、Taq DNA聚合酶浓度、引物浓度、模板DNA用量设计5因素4水平试验,采用极差分析法和方差分析法对试验结果进行分析。并对退火温度和循环次数进行筛选,建立绿竹ISSR-PCR最佳反应体系和扩增程序。并利用优化后的体系对100条ISSR引物进行筛选。最终确定的最佳反应体系为:20μL的扩增体系中,d NTPs浓度为0.2 mmol/L,Mg~(2+)浓度为2.0 mmol/L,Taq DNA聚合酶浓度为1.5 U,引物浓度为0.4μmol/L,DNA浓度为60 ng,10×PCR Buffer体积为2μL、剩下用灭菌ddH_2O补全。各因素影响大小依次是:Mg~(2+)d NTPs模板DNATaq DNA聚合酶引物。扩增程序为:94℃预变性5 min;94℃变性45 s,(根据引物的退火温度)复性30 s,72℃延伸90 s,循环38次,72℃延伸10 min,4℃保存。以此体系为基础进行引物筛选,在100条ISSR引物中筛选出14条扩增条带清晰、多态性较高、重复性好的引物。     

猕猴桃SCoT遗传多样性分析及指纹图谱的构建

利用SCoT标记对32个猕猴桃品种进行了遗传多样性分析。从47个SCoT引物中筛选了11个引物进行PCR扩增,共扩增出185个条带,其中多态性条带180个,多态性比率为97.30%。各引物Nei's基因多样性指数（H）平均为0.238 4,Shannon's信息指数（I）平均为0.377 8。利用UPGMA构建32份猕猴桃种质资源的聚类树状图。在遗传相似系数为0.78处可将32个猕猴桃品种分为5组,聚类结果与形态学分类基本一致。利用4条引物扩增的16个多态性位点构建了32个猕猴桃品种的DNA指纹图谱,可以将32个猕猴桃品种区分并准确鉴定。     

用任意引物PCR进行基因多态性分析时最佳反应条件的建立

用任意引物进行基因组指纹分析是检测DNA多态性的一种通用方法,对遗传学图谱绘制、系统发育学和种群生物学都很有用.由于任意引物PCR(AP-PCR)影响因素很多,获得理想的指纹扩增图谱比较困难,有必要寻找一种简单有效的方法建立最佳扩增体系.对Mg²⁺浓度,模板浓度、引物浓度等三个因素进行优化选择AP-PCR扩增反应实验研究.实验结果表明：Ap-PCR反应的最佳反应条件为2 mmol/L MgCl₂,50 ng的DNA模板及0.3 μmol/L的引物浓度,在上述条件下获得的AP-PCR产物最丰富,条带清晰.     

节瓜ISSR-PCR反应体系的建立与正交优化

旨在开展节瓜种质资源分类鉴定与遗传多样性研究。通过正交试验设计与单因素分析相结合的方法,对节瓜ISSR-PCR反应体系5个因素(模板DNA浓度、dNTP浓度、Mg2+浓度、引物浓度与Taq聚合酶浓度)在4个水平上进行优化分析,建立了节瓜稳定可靠且具丰富多态性的最佳反应体系,进而对引物退火温度进行梯度试验分析。结果表明,20μL节瓜ISSRPCR最佳反应体系为70 ng模板DNA、0.2 mmol/L dNTP、1.2 mmol/L Mg2+浓度、0.96μmol/L引物、0.8 U Taq DNA聚合酶和2.0μL10×buffer;引物IS807最佳退火温度为53℃。以此为基础,利用4条引物对4份节瓜种质进行最佳反应体系稳定性验证,证明该体系稳定可靠、扩增谱带清晰、多态性丰富且重复性较好。     

中国鸭茅主栽品种DNA指纹图谱构建

利用SSR标记和SCoT标记构建了我国主栽的21个鸭茅品种的DNA指纹图谱。从180对SSR引物和80个SCoT引物中,筛选出多态性高、谱带清晰的SSR引物和SCoT引物各24个。24对SSR引物在供试材料中共检测到186个条带,其中多态性条带为175个,品种特异条带6个,平均多态性比率94.03%,多态性信息量均值0.845,Shannon指数变幅0.4479~0.6549,基因多样性指数变幅0.2946~0.4633,可鉴别的品种数2~21个;利用24个SCoT引物在供试材料中共检测到321个条带,其中多态性条带为249个,品种特异条带6个,平均多态性比率76.33%,多态性信息量均值0.907,Shannon指数变幅0.2588~0.6329,基因多样性指数变幅0.1695~0.4451,可鉴别的品种数1~21个;5对SSR引物和5个SCoT引物在10个品种上具有唯一特征谱带,最终综合各项指标筛选出5个引物(A01E14、A01K14、B03E14、D02K13和SCoT23)上的37个条带用于鸭茅品种DNA指纹图谱构建,数据库中每个品种均具有唯一DNA指纹编码,构建的DNA指纹数据可用于鸭茅品种真伪鉴定,为品种权保护提供了科学依据。     

广西野生桃金娘SRAP体系优化及建立北大核心CSCD

利用均匀设计方法优化了桃金娘SRAP反应体系。得出最佳反应体系,其总反应体积为25μL,包括2.5μL10×PCR buffer,1.0U Taq DNA聚合酶,20 ng模板DNA,0.2 mmol.L-1 dNTPs,0.3μmol.L-1引物,2.5 mmol.L-1Mg2+。采用优化的扩增体系,以Me1-Em11引物组合对8个参试种质进行SRAP扩增,扩增出的条带清晰、多态性好。所确立的体系稳定可靠,适于进行桃金娘的SRAP遗传分析。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.