植物激素对驳骨丹茎愈伤组织生长和器官再生的作用

在驳骨丹离体茎切段培养中,用MS基本培养基,分别附加2毫克/升BA和0.2毫克/升NAA诱导愈伤组织,附加1毫克/升BA诱导芽分化;以2/1MS基本培养基分别附加0.5毫克/升NAA、IBA、IAA和2,4-D进行诱导发根试验,除2,4-D无效外,均能生根形成再生植株。根据上述试验结果,设计不同浓度的BA和NAA组合,进行愈伤组织继代培养,讨论这两种激素对愈伤组织生长和器官再生的调节作用。主要结果为:1.低浓度的BA和NAA组合比较有利促进愈伤组织的生长,且以中等浓度的BA和低浓度NAA的效果最佳;2.单独附加BA,其浓度在0.25—4.0毫克/升范围内,都能促进芽分化,而完全抑制了根的发生。当单加NAA,在0.5—6.0毫克/升的浓度范围内,能促进根的形成,而随其浓度的升高抑制芽的分化;3.细胞分裂素与生长素的比值>0.5时,有利芽分化而抑制根的发生,当比值<0.6时,有利根形成而抑制或减弱细胞分裂素促进芽分化的作用。在这里讨论了生长素和细胞分裂素之间对报、芽形成的拮抗作用。     

圆叶娃儿藤离体组织培养的快速繁殖研究

圆叶娃儿藤实生苗的上胚轴在H+6—BA2毫克/升的培养基上可产生大量不定芽,并发展成无根苗。当无根苗转至1/2 MS+NAA0.25毫克/升的培养基上10天后即可生根获得完整再生植株并移栽成活。通过这一实验程序已可使组织培养这一方法成功地作为圆叶娃儿藤快速繁殖的一种手段。     

石梓茎尖培养

植物名称:石梓(Gmelina arborea)材材类别:侧枝顶芽。切取5毫米左右的茎尖接种。培养条件:基本培养基均为MS。(一)不定芽分化培养基,每升添加1.0毫克BA;(二)幼苗培养基,每升添加0.8毫克BA和0.5～1.0毫克IAA;(三) 生根培养基,每升添加0.5毫克IBA,或先经125ppm浓度的IBA溶液处理,再培养在无激素的液体MS培养基上。培养温度在24℃以上,室内自然散射光。生长和分化情况:(一)在MS+BA 1.0毫克/升培养基上,培养十天以后,逐渐形成3～4个或更多个不定芽,间或有少量幼苗形成,二十天以后如不转移到MS+BA     

枳多芽苗的诱导

枳幼苗茎段的腋芽在含BA(0.5毫克/升)和NAA(2毫克/升)的MS培养基上能诱导出大量丛生芽,丛生芽苗茎段的腋芽在含BA(0.5-2毫克/升)的MS继代培养基上又可增殖,将无根幼苗分别转至含IAA、IBA和NAA(均为1毫克/升)的MS培养基上则生根形成完整植株。     

紫云英叶片及叶肉原生质体的培养

本工作研究了豆科植物紫云英的叶片及叶肉原生质体的培养。叶片培养实验表明,诱导愈伤组织的最适培养基为MS加1.0-2.0毫克/升2,4-D和0.25毫克/升KT;诱导根分化需加1.0—5.0毫克/升NAA和0.5毫克/升BA;而苗分化则以0—0.5毫克/升IAA和0.5毫克/升BA为好。高浓度的NAA有利于根分化而抑制茎芽形成;高浓度的IAA对根和芽分化都有抑制作用。叶肉原生质体分离和培养试验表明,紫云英叶肉原生质体的释放及其培养活力受叶龄、植株生理状态和酶浓度的影响。叶肉原生质体在改良的KM8P培养基中能分裂。用改良KM8细胞培养基定期稀释,可使分裂持续进行而得到细胞团。BA和2,4-D为诱导紫云英叶肉原生质体分裂所必需。其最佳组合激素为BA 0.21毫克/升和2,4-D 1.13毫克/升。葡萄糖作为渗透压稳定剂时,其浓度明显影响原生质体的存活率。弱光条件下培养比黑暗培养有利于叶肉原生质体分裂。由叶肉原生质体形成的愈伤组织能形成瘤状结构和根。     

罗汉果叶组织培养的研究

用MS基本培养基培养罗汉果叶组织,研究植物激素对形成器官的影响。不同细胞分裂素的试验结果表明:在试验浓度范围内(0.5—1.0毫克/升)。BA明显促进茅的形成,KT和对照(基本培养基)均无形成茅,BA为罗汉果叶组织形成芽所必需的。IAA或IBA0.5毫克/升和BA1.0毫克/升配合使用。对叶组织形成芽有增效作用。茅进一步长出茎叶,将茎叶转入含有NAA0.2毫克/升的1/2MS的生根培养基,明显促进根的形成和发展成完整植株。 我们进行长滩果,拉江果及青皮果等三个罗汉果主要品种的叶组织离体培养,均能诱导形成丛生茅,将丛生叶分开,可不断扩大繁殖,促进芽的增殖,能获得大量绿苗。幼苗移栽土壤获得成活,成活率达80—100％,幼苗生长良好。     

川芎的组织培养及植株再生

植物名称:川芎(Ligusticum wallichii Franch)材料类别:长有1—2片真叶的幼嫩茎段和叶片培养条件:基本培养基采用MS。诱导愈伤组织培养基为MS,每升补加2,4-D2.0毫克,6BA0.4毫克;诱导芽分化培养基为MS,每升补加6BA0.4毫克、IAA0.5毫克;诱导根分化培养基为1/2MS,每升补加6BA0.2毫克,IAA1.0毫克。培养温度     

马蹄莲组织培养和快速繁殖

本文报道从新西兰引进马蹄莲杂交种的8个优良品种。研究植物激素及培养基物理性质对器官形成的影响。试验结果表明细胞分裂素BA0.5—1.0毫克/升明显促进芽的形成和增殖。随着BA浓度的增高.形成芽数也随着增多。备品种均能诱导形成丛生芽。低浓度BA或NAA有利于芽发育和诱导生根。固体培养有利于诱导彤成丛生芽;而液体静置培养促进芽发育和生根。各品种的试管苗成功地移栽田间并已开始开花。     

赤霉素对烟草叶组织培养中芽形成的抑制效应

本文研究了赤霉素(GA)对烟草叶组织培养中芽形成的影响。单加GA 能明显促进叶组织膨大,叶肉细胞明显增大,但无细胞分裂发生。在诱导成芽的培养基中(2毫克/升BA)加入不同浓度的GA(0.5—5.0毫克/升),均强烈抑制芽的形成。在培养的不同时间进行的不同培养基之间的转移培养试验说明,GA 的作用主要发生在第一个星期内。组织细胞学观察表明,在加有GA 和BA 的培养基上,叶组织中极少形成分生细胞团。GA 抑制芽形成的作用显然与此密切相关。一旦培养的组织中形成了有一定结构的分生细胞团,这一成芽过程似不再为GA 所逆转。     

甜茶组织培养研究

甜茶的茎段和实生苗培养在MS基本培养基中,研究植物激素对器官形成的影响,试验结果表明BA0.5-2.0毫克/升明显促进芽的形成和增殖;而对照(基本培养基)无形成芽。细胞分裂素对芽的起动是必需的。BA0.5-2.0毫克/升和GA_s1.0毫克/升配合使用,对茎段形成芽和增殖反而减少,但形成的苗较高和幼叶生长良好。通过继代培养,可繁殖大量小苗,它揭示出同一块外植体生长出许多小植株的可能,将无根苗转入含有IBA0.25-0.50毫克/升的1/2MS培养基中,能诱导生根,发展完整植株。试管苗移植土壤中,获得成功,幼苗生长良好。     

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).