水稻第十染色体短臂的等臂四体及其在着丝点定位中的应用

为了确定连锁图上着丝点的位置,常常需要一些特殊的遗传材料,如端部着丝点染色体和等臂染色体材料等等。在水稻上,为了获得这类遗传材料,从中籼３０３７同源三倍体后代产生的非整倍体中,在筛选初级三体的同时,进行了等臂染色体变异材料的筛选。其中在三体１０的后代中发现了１株形态与三体１０相似的变异株,经细胞学检查,证明它是第十染色体短臂的等臂四体。利用该等臂四体及其自交后代中分离出的次级三体,以及相应染色体的初级三体和正常二倍体为材料,通过ＲＦＬＰ不同分子标记在这些材料上所表现剂量效应的不同,确定Ｇ１１２５、Ｇ３３３、Ｌ１６９等３个分子标记位于第十染色体短臂上,Ｇ１０８４及其它１６个分子标记位于第十染色体长臂上。参照Ｋｕｒａｔａ等的分子图谱,将第十染色体的着丝点定位在分子标记Ｇ１１２５和Ｇ１０８４之间,两标记相距３．２ｃＭ［８］。     

四倍体水稻花药培养筛选初级三体的研究

以同源四倍体水稻 ( Oryza sativa L.)各世代杂种和四倍体籼、粳原种为材料进行花药培养 ,诱导花粉植株再生。根据三体植株表型上相互区别的特性 ,且又显著区别于二倍体 ,对其中所诱导的 1 5个花药培养品系 4 390株 H1花粉植株进行了重点固定和染色体镜检。结果表明 ,花粉 H1植株染色体组成包括二倍体、四倍体和非整倍体 ,其频率分别为 88.0 %、5 .5 3%和 6.67%。鉴定出 2 72株三体 ,占全部花粉植株的 6.2 0 %。对照已配套三体系的形态 ,将鉴定的三体株划分为 9种类型 ,并对其中的 91 2 4 - 7窄叶三体进行粗线期核型分析 ,鉴定为三体 8。将三体 8的种子播种 ,在 H2 代苗期统计额外染色体的传递率 ,三体株占 34 .1 1 % ,其农艺性状也同于 H1亲代     

利用水稻成套端三体进行DNA序列快速染色体臂定位

以水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．ｓｓｐ．ｉｎｄｉｃａ）“中籼３０３７”成套端三体为材料,通过制备不同染色体两个端三体的等量ＤＮＡ膜,并与等定位的分子标记或ＤＮＡ序列杂交,成功地将严重偏分离的零等位标记多拷贝标记０７３的不同片段,以及着丝点相关重复序列ＲＣＳ１定位互相应的染色体臂上。说明在水稻中,不同染色体臂的端三体可以弥补连锁定位方法的一些不足。     

黄瓜同源三倍体创制及减数分裂行为观察

采用常规杂交法研究黄瓜二、四倍体杂交过程中亲本育性、授粉组合及亲本基因型对杂交结实率的影响,并利用减数分裂制片法对获得的黄瓜同源三倍体进行了花粉母细胞减数分裂行为的观察.结果显示:(1)同源四倍体白交结实率比较低(13.0%～14.5%),可能与其花药内所包含的正常花粉粒比例小及花粉管萌发长度较短有关.(2)二、四倍体杂交组合的结实率很低(0.26%～0.02%),但在两种配组方式之间存在着明显差异,即以同源四倍体黄瓜为父本和二倍体黄瓜为母本的杂交结实率比较高,反之则杂交结实率比较低.(3)在二、四倍体杂交过程中,二、四倍体的基因型对杂交结实率的影响较大,以杂交双亲同属一个基因型的杂交效果较好.(4)同源三倍体花粉母细胞减数分裂过程与二倍体基本相同,但存在较高频率的染色体异常行为:中期I染色体构型复杂,在大多数花粉母细胞中可观察到单价体、二价体、三价体的存在;中期Ⅰ和Ⅱ有少数染色体游离于赤道板外;后期I和后期Ⅱ常出现落后染色体、染色体桥及细胞分裂不同步现象,其最终结果导致了不正常四分体和不可育配子的形成.(5)同源三倍体花粉粒的平均可染率和萌发率分别为18.8%和11.3%.研究结果表明,黄瓜二、四倍体正反交能直接获得同源三倍体材料;同源三倍体花粉母细胞减数分裂异常导致不育配子的形成是引起其育性低的细胞学原因;同源三倍体的部分育性为通过同源三倍体的回交来选育初级三体系奠定了基础.     

谷子三体系列的建立

以谷子（Ｓｅｔａｒｉａ ｉｔａｌｉｃａ （Ｌ．） Ｂｅａｕｖ．）四倍体为母本、二倍体为父本杂交。在２１００ 个杂交后代中得到５ 株三倍体。对三倍体植株授以二倍体花粉,将收获的种子播种后,从所培育的植株中获得９ 种三体共２８３ 株。其中８ 种具有明显的形态特征,只有三体Ⅳ植株形态与二倍体非常相似     

水稻花粉植株非整倍体的细胞遗传学

在290棵水稻花粉植株中获得水稻非整倍体植株,频率为10.7％。其中初级三体为6.7％,四体为1.7％,单体为1.3％,缺体为1.0％;双三体为0.7％。额外染色体粗线期分析表明,19个初级三体分别归属于三体3,三体4,三体8,三体10和三体12。粗线期分析还鉴定了四体、双三体、缺体和单体的染色体组成。花粉母细胞减数分裂的染色体行为表明,非整倍体花粉植株的主要染色体畸变为粗线期的疏松配对、单价体;终变期的单价体和四价环;中期Ⅰ的染色体拖曳及四价体;后期Ⅰ的染色体桥和落后染色体。     

利用初级三体定位水稻光敏核不育基因

自 1 973年 Ramanunjam首次获得三体 ( 2 n=2 x 1 =2 5)植株以来 ,已报道的粳型初级三体有日本晴 NT和籼型初级三体 IR36、Sona、广陆矮 4号 [1 ]及籼型初级三体 30 37[2 ]等。获得细胞学证据并用于定位研究的仅有日本晴三体和 IR36三体 [3,4]。目前 ,利用形态标记和分子标记定位水稻光敏核不育基因的报道较多 ,且涉及到第 5、7和第 1 2三条染色体 [5,6] 。我们拟以粳型光敏核不育系为父本 ,台中 65初级三体为母本配组 ,定位光敏核不育基因 ,对粳型光敏核不育基因定位结果进行验证 ,以期为光敏核不育的利用与研究提供理论依据。1 　材料…     

水稻抗白叶枯病菌毒素细胞无性变异系的初步筛选

应用湖北水稻白叶枯病强毒菌株“江陵６９１”活细菌、细菌培养滤液、病菌粘液多糖和菌体多糖。对水稻粳１０５、粳３０３７和科选１号的幼穗及花药所形成的愈伤组织进行共培养筛选。获得体细胞再生植株４４３株,花粉植株３１株,其中１７株为单倍体（ｎ＝１２）。同工酶谱显示,筛选出的粳１０５愈伤组织的过氧化物酶同工酶活性加强,带数增多。     

离体培养柑桔小胚获得三倍体植株

兰倍休植株因不能进行正常的减数分裂, 常产生败育的胚囊和花粉;又因柑桔属植物具 有单性结实的能力,因而人工培育三倍体植株 已成为获得无核柑桔品种的一条重要途径。在 柑桔属植物中,获得三倍体主要有三条途径： (1)通过胚乳离体培养诱导三倍体植株［[I>; (2) 四倍体品种同二倍体品种杂交,获得三倍体[41 . (3）单胚的二倍体柑桔品种作母本进行杂交或 自然授粉后,可产生一定比例的,重量为正常种 子1/6至123的小粒种子,并已确定此小粒种 子是三倍体［[2,3,8,10]。这无疑为柑桔的三倍体培育 提供了一条简便、实用和快速的新途径。     

秋水仙素诱导大青杨同源三倍体

以黑龙江省苇河、带岭的大青杨为亲本,采用正交设计L16（4^5）对授粉后的雌花序施加0．2％～O．6％的秋水仙碱溶液进行染色体加倍试验,通过流式细胞术和染色体镜检方法检测变异植株的染色体倍性,共获得12株大青杨同源三倍体。结果表明,在授粉36～60h后用O．5％秋水仙碱溶液浸泡24h的诱导效果最好。大青杨三倍体植株叶长和叶宽分别高出二倍体2l％和45％;其叶片气孔长、宽高出二倍体55％和45％,气孔密度是二倍体的18％。     

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.     

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     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV