30%己乙水剂对玉米根系伤流液及其组分的影响

以玉米3138为材料,在大田和PVC管栽条件下研究了应用植物生长调节剂30％己乙水剂对玉米根系伤流量、伤流中无机离子流量、氨基酸组分及流量、激素流量等的影响,结果表明：30％己乙水剂可提高玉米根系伤流量,特别是大喇叭口期和籽粒形成期;提高了伤流中K,P,Ca,Mg,Si,Zn,Mn,Fe,B,Mo,Cu等无机元素流量,氨基酸总流量提高,主要的运输形式氨基酸Ser,Clu,Lys．Arg,Val,Ala,Leu,I1e,His,Try,Phe流量均明显增加,非蛋白质氨基酸GAba大幅度增加,伤流液中IAA在籽粒形成和灌浆期提高,授粉后伤流中Gas提高,CTKs在籽粒形成期提高,ABA在灌浆期提高,吐丝前低于对照。表明30％已乙水剂可促进根系吸收和合成物质向地上部分的输送,对促进地上部发育有重要作用。     

不同年代大豆品种根系活力的变化及其与植株生物量的关系

为探索不同年代大豆品种根系活力的变化及其与植株各器官生物量和根系伤流液重量的关系。以吉林省1923~2009年间育成的27个大豆品种为材料进行田间试验,在四叶期(V4),盛花期(R2),结荚盛期(R4)和鼓粒盛期(R6)测定根系活力、伤流液重量和植株各器官生物量。结果表明,随生育期的推进,植株器官生物量不断增加,而根系活力和伤流液重量则呈单峰曲线变化,在R4期达到最大。在R4期,植株根系活力、根系伤流液重量和器官生物量与育成年代均呈显著或极显著正相关,但在V4、R2和R6期均未达到显著水平。在R4期,根系活力与根系伤流液重量、植物器官茎、叶和根生物量呈显著或极显著正相关;各品种间地上部器官生物量与根系活力的比值差异不显著。大豆的遗传改良使地上部器官与根系活力协同演进,在根系活力增强的同时植株器官生物量和根系伤流液重量也增加,且在R4期,根系活力与植物器官生物量和根系伤流液重量相关最为密切;可以把R4期的根系活力作为高产育种的指标之一。     

镧对植物伤流液中氨基酸的成分及含量的影响（简报）

植物根系的伤流量及其内含物的变化常作为根系生理活动的指标.根系内有较强的合成氨基酸的能力,并将合成的部分氨基酸提供给地上部合成蛋白质,因之在根系伤流液中存在有大量的游离氨基酸.植物体内氨基酸的合成与代谢受多种因素的影响,其中包括营养状况.近年来,吴兆明等发现镧对植物不定根的分化、促进根系的生长及活力有明显     

转Bt基因抗虫棉(Gossyposium)伤流中Bt毒蛋白的运输

本文以常规棉品种‘石远321'和抗虫棉品种‘SGK321'与‘99B'为材料,通过考马斯亮蓝和ELISA方法分析了伤流中可溶性蛋白和Bt(苏云金芽孢杆菌)毒蛋白含量.结果发现,转基因抗虫棉伤流中可溶性蛋白含量显著高于常规棉,并在抗虫棉伤流中检测到了Bt毒蛋白,而常规棉伤流中没有Bt毒蛋白的存在.通过嫁接实验研究发现,将常规棉嫁接到转Bt基因抗虫棉砧木上,叶片中也有Bt毒蛋白的积累.这些结果说明,Bt毒蛋白可以通过木质部伤流液向地上部运输,并在叶片中积累,Bt毒蛋白由根系向地上部的运输对棉花的抗虫性是有益的.     

转Bt 基因抗虫棉(Gossyposium)伤流中Bt 毒蛋白的运输

本文以常规棉品种‘石远321’和抗虫棉品种‘SGK321’与‘99B’为材料, 通过考马斯亮蓝和ELISA方法分析了伤流中可溶性蛋白和Bt(苏云金芽孢杆菌)毒蛋白含量。结果发现, 转基因抗虫棉伤流中可溶性蛋白含量显著高于常规棉, 并在抗虫棉伤流中检测到了Bt毒蛋白, 而常规棉伤流中没有Bt毒蛋白的存在。通过嫁接实验研究发现, 将常规棉嫁接到转Bt基因抗虫棉砧木上, 叶片中也有Bt毒蛋白的积累。这些结果说明, Bt毒蛋白可以通过木质部伤流液向地上部运输, 并在叶片中积累, Bt毒蛋白由根系向地上部的运输对棉花的抗虫性是有益的。     

棉花幼铃发育过程中内源激素水平的变化及赤霉酸对它的影响

为了寻求内源激素水平与棉花幼铃脱落的关系,探讨棉花幼铃发育过程中内源激素的调节作用,分别研究了正常发育的幼铃、开花当天GA_3处理的正常铃、去柱头不受精、将在开花后4～6天脱落的幼铃,以及不受精但经GA_3处理因而不脱落的幼铃在发育或脱落过程中五类内源激素水平的变化。实验结果表明,在开花当天的正常子房中,已有IAA、ABA和CTK的存在,并释放甚多Eth,GA则在开花后第6天始可测出。随着幼铃日龄增长,五类激素的含量水平各有变化。IAA的含量在第6天急骤上升,第10天达到高峰,以后下降。CTK也在第6天急骤增高,并继续平稳上升,直至实验结束。开花当天的幼铃即释放相当多的Eth,开花以后逐渐下降,正常幼铃也含有相当高的ABA。至于日龄1～5的不受精幼铃及GA_3处理不受精幼铃,其IAA和CTK两类激素的含量,在处理和对照之间,差异不大;但是不受精幼铃中ABA含量和Eth释放量的变化却十分激烈,两者在幼铃脱落前都剧烈增加,但GA_3处理不受精幼铃不出现这种急骤增长的高峰。与此相应的是GA_3有效地防止了不受精幼铃的脱落。各类内源激素在铃壳和种子中的分布是不同的。IAA和CTK是种子多于铃壳,ABA和GA则铃壳多于种子。从以上实验结果看来,幼铃中ABA和Eth水平变化与幼铃脱落是密切相关的,脱落幼铃在脱落前ABA和Eth剧烈     

麦棉套作复合根系群体对棉株氮素吸收与分配的影响

在盆栽麦棉套作条件下,于2003～2004年设置麦棉自然根系(麦棉根系和肥水均可相互通过)、麦棉纱网隔根(肥水可相互通过,麦棉根系不能相互通过)和麦棉塑膜隔根(麦棉根系和肥水均不能相互通过)3种麦棉根系处理,运用小麦叶片¹⁵N富积标记法和¹⁵N同位素稀释法,研究麦棉复合根系群体对棉花氮素吸收与分配的影响.结果表明,在麦棉套作群体中,既存在麦棉共处期小麦对棉花根区氮素的竞争,又存在小麦根区及其所吸收氮素向棉花的转移.棉花根系吸收的¹⁵N肥料大多分配到地上部,根系分配的量较少,且麦棉自然根系处理地上部的¹⁵N标记肥料氮的吸收率(NUR)最大,纱网隔根处理次之,塑膜隔根处理最少.在麦棉共处期,麦棉自然根系处理棉花的植株从¹⁵N标记肥料中吸收的氮占其全氮的百分率(Ndff)和NUR均低于隔根处理.至棉花初花期(小麦已收获,秸秆原位埋入土壤中),麦棉自然根系处理棉花吸收的氮素主要来源于化学肥料而非秸秆降解物.棉株不同器官所分配的¹⁵N标记肥料比例不同,棉花生殖器官中¹⁵N含量明显高于其他器官.麦棉自然根系处理棉株生物量也高于隔根处理.     

测定植物离体根系伤流强度微量快速变化的装置——微量液滴器

由于植物根系伤流与水分和盐类吸收过程的密切关系,对根系伤流的研究从40—50年代开始,日益受到重视。对根系伤流强度(bleeding rate)的测定和分析是当前研究根系水分生理的基本方法之一。目前根系伤流强度的测定方法主要有三类:称重法,体积测定法(包括目前应用最普遍的刻度毛细管法)和液滴法。其中后两类较多地用于根系伤流强度快速变化的测定。     

苗期遮荫对棉花产量与品质形成的影响

为揭示棉麦两熟共生期遮荫对棉花产量与品质形成的影响。在棉花苗期利用模拟棉麦两熟共生期遮荫的方法进行了研究。结果表明,遮荫对棉铃形成的影响因果枝,果节部位而异,遮荫有利于棉株下（1-3果枝）,中（4-6果枝）,上（7-9果枝）部果枝内围（1-2果节）铃的形成,对外围（≥3果节）尤其顶部果枝（≥10果枝）外围铃形成不利,从而决定铃重也随果枝,果节部位相应地变化,但遮荫对单株平均铃重的影响畔 小,变遮荫棉花籽棉产量而论,下,中部果枝的内围铃籽棉产量高于常规棉,在上,顶部果枝则相反,各部位果枝外围铃的籽棉产量均低于常规棉,遮荫棉花内,外围铃分布为1：0.36(常规棉为1：0.58),产量分布为1：0.42(常规棉为1：0.72)。苗期遮荫对棉纤维,棉籽品质性状的影响也主要在顶部果枝和上部果枝外围铃,综合分析遮荫棉花产量与品质的形成,棉花苗期耐遮荫性品种间存在差异。在本研究中以中9418耐遮荫性最强,中棉所19和春矮早次之。     

麦棉套作复合根系群体对棉株氮素吸收与分配的影响

在盆栽麦棉套作条件下,于2003～2004年设置麦棉自然根系（麦棉根系和肥水均可相互通过）、麦棉纱网隔根（肥水可相互通过,麦棉根系不能相互通过）和麦棉塑膜隔根（麦棉根系和肥水均不能相互通过）3种麦棉根系处理,运用小麦叶片15N富积标记法和15N同位素稀释法,研究麦棉复合根系群体对棉花氮素吸收与分配的影响．结果表明,在麦棉套作群体中,既存在麦棉共处期小麦对棉花根区氮素的竞争,又存在小麦根区及其所吸收氮素向棉花的转移．棉花根系吸收的15N肥料大多分配到地上部,根系分配的量较少,且麦棉自然根系处理地上部的15N标记肥料氮的吸收率（NUR）最大,纱网隔根处理次之,塑膜隔根处理最少．在麦棉共处期,麦棉自然根系处理棉花的植株从15N标记肥料中吸收的氮占其全氮的百分率（Ndff）和NUR均低于隔根处理．至棉花初花期（小麦已收获,秸秆原位埋入土壤中）,麦棉自然根系处理棉花吸收的氮素主要来源于化学肥料而非秸秆降解物．棉株不同器官所分配的15N标记肥料比例不同,棉花生殖器官中15N含量明显高于其他器官．麦棉自然根系处理棉株生物量也高于隔根处理．     

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.     

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.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).