紫薯提取物对花叶芋试管苗生长的影响

实验以花叶芋无菌苗为材料,通过研究有机提取物种类,提取物浓度及提取物提取方式对花叶芋试管苗生长的影响,筛选出最适合花叶芋试管苗培养的天然有机提取物。实验结果表明：MS基本培养基中添加紫薯提取物时,花叶芋试管苗生长优于其他植物提取物;当紫薯提取物浓度为10％时,花叶芋试管苗长势最佳;比较紫薯上清液、沉淀物、混合液3种提取方式,紫薯混合液对花叶芋的生长最为有利。     

花叶芋的组织培养和植株再生

双色花叶芋(Caladium bieolor)和亮白花叶芋(C.hortulanum)的叶及花序外植体在加有2,4-D 和激动素或只加有2,4-D 的培养基上产生了愈伤组织,它们在转移到无激素或含激动素和低浓度生长素的培养基上以后分化出大量胚状体,并进一步长成小植株。本工作为花叶芋的快速繁殖提供了方法。     

两种芋属(天南星科)植物的核型研究

报道了芋属两种植物的核型,结果如下:异色芋2n=2X=28=18m+10sm,属于“2B”类型;花叶芋2n=2X=28=20m(8sat)+8sm(2sat),属于“2A”类型;花叶芋的核型及两个种之间的核型比较系首次报道。     

天南星科观叶植物多

天南星科有2000多种,绝大多数分布在热带、亚热带地区。该科植物耐荫性强,叶片、佛焰苞耐观赏种类丰富,因此拥有众多的室内观叶植物佳品。常见栽培的有龟背竹、广东万年青、花叶芋、合果芋(箭叶芋)、马蹄莲、海芋、绿萝、红宝石喜林竹、绿宝石喜林芋、白鹤芋、花叶万年青等等。其中龟背竹、喜林     

花叶芋(Caladium bicolor)组培的改进及细胞组织学观察

花叶芋(Calalium bicolor),又名五彩芋,属天南星科,是一种美丽的观叶植物,原是通过块茎繁殖,但其休眠期长,增殖速度慢,因此,利用组培扩大繁殖,以满足市场需要。关于花叶芋的组培,已有不少报道,但对合适的培养基的筛选,分化的途径都还有研究的必要。为此,我们以花叶芋叶柄、叶片为材料进行了初步研究现结果如下:1.愈伤组织的诱导和培养基的改进:所用培养基中在 MS 附加2,4-D1ppm,KT 1ppm、     

不同品种花叶芋的组织培养

采用12个不同品种花叶芋的叶片和叶柄进行组织培养,发现不同品种的最佳外植体并不一致,大叶型品种以叶片、小叶型品种以叶柄为佳。试管苗叶片和叶柄比栽培苗的叶片与叶柄更有利于作离体繁殖的外植体。不同外植体对培养基要求则差别不大。花叶芋离体叶片和叶柄在MS+BA 2mg/L+NAA 0.2～0.6mg/L培养基上可直接分化成小芋块,小芋块剖面坚实呈白色,以I-KI溶液染色呈现深蓝色,与盆栽苗芋块相同。小芋块在降低激素浓度培养基即于MS补加BA与NAA各0.1mg/L培养基上,即分化出大量的再生植株。在芋块上分化出芽,在芋块与苗之间分化出根。     

国产芋属花粉形态

通过光镜和扫描电子显微镜观察了芋属(Colocasia Schott)6种、1变种、1品种的花粉形态,其中贡山芋C．gaoligongensis,龚氏芋C．gongii,李氏香芋C．lihengiae,花叶芋C．bic-olor4个种为首次报道。本属花粉为圆球形,无萌发孔。外壁纹饰分为两类：大野芋C．giga-ntea外壁光滑无刺,其余各种均具刺。花粉大小为20．07—32．76μm。     

花叶芋(天南星科)的花器官发生

利用扫描电镜首次观察了天南星科花叶芋(Colocasia bicolor) 的花器官发生过程。花叶芋的肉穗花序由无花被的单性花构成, 雌花发生于花序基部, 雄花发生于花序上部, 中性花位于花序中间部位。雄花: 3 或4 个初生雄蕊原基轮状发生, 随后每个初生原基一分为二, 形成6或8个次生原基; 一部分次生原基在其后的发育过程中融合, 形成5 或7 枚雄蕊; 雄花发育过程中未见雌性结构的分化; 花药的分化先于花丝; 雄蕊合生成雄蕊柱。雌花: 合生心皮, 3或4个心皮原基轮状发生, 未见雄性结构的分化。中性花来源于雌雄花序过渡带上, 属于雄蕊原基的滞后发育以及发育成熟过程中的退化; 与彩叶芋属(Caladium)不同, 此过渡区未见畸形两性花。初生雄蕊原基二裂产生次生原基的次生现象在目前天南星科花器官发生中显得比较特殊, 同时初步探讨了次生原基的融合方式。     

花叶芋芽球人工种子研究

将花叶芋(Caladium biocolar)的无菌嫩叶切块,培养在补加有6-BA(1mg/L)、IAA,(0.2mg/L)和CH(500mg/L)的MS琼脂培养基中,20天后在切块的边缘及表面形成圆形淡黄色突起,转移到低激素或无激素的MS培养基上继代培养,形成的深绿色芽球组织,长期保持旺盛的分化能力。芽球用海藻酸钠包裹并在0.1M氯化钙容液中凝聚而成的人工种子胶粒,在无菌培养条件下,成株率可达100％。同时还观察了不同包埋胶、播种条件、芽球质量等对花叶芋芽球人工种子生长的影响。实验表明,对于一些尚不能应用悬浮培养法制备大量体细胞胚的植物来说,芽球组织也是一种制作人工种子的好材料。     

中国芋属植物染色体数目及5个种的核型报道

对中国 8种 (包括 1变种 )芋属 (ColocasiaSchott)植物的体细胞染色体数目和其中 5个种的核型进行了报道。结果分别为 :异色芋C heterochromaH .LietZ .X .Wei,2n =2x =2 8=1 8m 1 0sm ;龚氏芋C gongiiC .L .LongetH .Li,2n =2x =2 8=1 8m (4SAT ) 1 0sm(4SAT) ;贡山芋C gaoligongensisH .LietC .L .Long ,2n =2x =2 8=2 4m 4sm ;李氏香芋C lihengiaeC .L .LongetK .M .Liu ,2n =2x =2 8=1 8m (1SAT ) 6sm 4st;花叶芋C bicolorC .L .LongetL .M .Cao 2n =2 8;紫杆芋C lihengiaeC .L .LongetK .M .Liuvar.nigraC .L .Long 2n =3x =4 2 ;大野芋C gigantea (Bmume)Hookf.,2n =2x =2 8=2 2m 4sm 2st;山芋C konishiiHayata 2n =2 8。除李氏香芋、龚氏芋、大野芋和山芋外 ,其余染色体数目均为首次报道。在核型方面 ,异色芋、龚氏芋、李氏香芋、贡山芋的核型均为首次报道     

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).