普通番茄叶肉原生质体和多毛番茄茎尖原生质体的电融合

普通番茄叶肉原生质体和多毛番茄茎尖原生质体在一交变电场中(正弦波;1mHz,200v/cm)可发生双向电泳而随机排列成串。再附加单个直流方波脉冲,可诱导相邻原生质体的融合,适宜的融合脉宽为40μs,电压幅度为3000v/cm。最高融合率可达57%。培养经电融合处理的原生质体,观察到了少数原生质体的第1次分裂。     

水稻原生质体电融合时的参数选择（简报）

水稻（0862和台北309）原生质体电融合最佳条件是交流电场强度250V／cm,频率600kHz;高压直流脉冲幅值1．65kV／cm,脉冲持续时间50μs,脉冲间隔时间3．0S。融合率最高可达275％．在上述条件下,电场处理基本不影响原生质体的活力。     

卵裂球电脉冲融合制作昆明小鼠四倍体胚胎

为制作四倍体小鼠胚胎 ,用 4种脉冲电压强度 (6 0 0、 80 0、 10 0 0和 12 0 0V/cm )和 3种脉冲宽度(10、 30和 5 0 μs)组合 ,对 2 -细胞昆明小鼠胚胎做了融合实验。 6 0 0V/cm× 5 0 μs和 12 0 0V/cm× 30 μs两种组合融合率最高 ,分别为 91 6 %和 93 0 % ;而 6 0 0V/cm× 10 μs和 12 0 0V/cm× 5 0 μs时均显著低于其他各种组合 ,融合率分别为 5 8 9%和 6 0 2 %。以上结果表明 ,一定的脉冲电压强度是胚胎融合的必要条件 ,而脉冲宽度是影响胚胎融合及其后期发育的关键因素。激光共聚焦显微镜对融合后两细胞核的观察暗示 ,细胞核的迁移、靠近和融合是自发过程     

巴马小型猪转基因克隆胚胎融合/激活条件的优化

本试验旨在建立一个适合于巴马小型猪转基因克隆胚胎生产的高效融合/激活体系,为生产足量的转基因克隆胚胎奠定基础。把h GFAP-Ds Red基因转入巴马小型猪肾脏成纤维细胞并以转基因细胞为供体核,构建重构胚胎,比较各组胚胎的发育能力,筛选出适合转基因克隆胚胎生产的融合/激活参数。试验结果表明,脉冲时程30μs、1次脉冲、场强1.5 k V/cm组,融合率、分裂率和囊胚率(87.32%,69.79%,21.74%)均显著(p0.05)高于1.0 k V/cm组(78.63%,45.07%,9.65%)和2.0 k V/cm(63.87%,36.72%,5.49%);脉冲时程30μs时,融合率和囊胚率(81.92%,19.56%)均显著(p0.05)高于20μs(69.19%,7.51%)和40μs(69.28%,6.51%);3次脉冲组的融合率、分裂率和囊胚率(63.32%,38.09%,5.49%)均显著(p0.05)低于1次脉冲(81.92%,63.40%,22.15%)和2次脉冲组(81.59%,67.46%,12.97%)。本实验室条件下,最适合于转基因克隆猪胚胎生产的融合/激活参数是1.5 k V/cm、30μs和1次脉冲。     

利用微秒和微纳秒脉冲电场诱导细胞融合

[目的]以小鼠骨髓瘤(SP2/0)细胞作为实验材料,比较了SP2/0细胞在不同微秒(μs)脉冲和微纳秒(μs/ns)复合脉冲电融合的细胞存活率和融合率,并确定了最优的μs/ns复合脉冲电融合参数。[方法]将SP2/0细胞分别用Hoechst 33342和碘化丙啶(PI)进行染色,分别选取3组μs脉冲和3组μs/ns复合脉冲对染色后的SP2/0细胞进行电融合,通过荧光显微镜观察融合后细胞的存活率和融合率。[结果]对比不同μs和μs/ns复合脉冲电融合存活率和融合率结果得知,μs/ns复合脉冲比μs脉冲电融合效果更好,且电融合参数为2. 5 k V/cm、20μs、1次,10 k V/cm、200 ns、8次时存活率和融合效率相对最好,存活率和融合率分别为88. 5%±6. 2%和80. 1%±2. 6%。[结论]通过采用不同μs和μs/ns复合脉冲电融合比较了SP2/0细胞的存活率和融合效率,结果显示μs/ns复合脉冲电融合参数在2. 5 k V/cm、20μs、1次,10 k V/cm、200 ns、8次时,存活率比μs脉冲电融合提高6. 4%,融合率提高23. 3%,为利用μs/ns复合脉冲研究杂交瘤细胞电融合奠定了基础。     

香菇和侧耳属间原生质体的电融合研究

从培养在液体培养基中的香菇、美味侧耳和平菇的单核菌丝用酶法分离了原生质体。施加0.5MHz、500PV/cm的正弦波和μs、6000PV/cm方形脉冲的电场诱导下使其电融合。电融合后的融合子和原生质体在固体培养基上植板培养成菌落。在显微镜下检查融合子菌株菌丝的锁状联合选出从融合子长成的菌株。香菇和美味侧耳的融合菌株产生频率为61.53%,香菇和平菇的融合菌株产生频率为32.58%。根据融合菌株与亲本的拮抗作用和他们的过氧化物同工酶和酯酶同工酶的电泳酶谱与其亲本酶谱的不同,证实这些融合菌株是从融合的异核体生长成的。同时讨论了电融合方法和结果。     

酿酒酵母缺陷型原生质体的形成再生及融合条件的探讨

营养缺陷型作为酿酒酵母(Saccharomyces Cerevisiae)单倍体融合亲株的遗传标记。采用营养缺陷型LY—2和LY—4菌侏的对数生长前期的细胞,在0.5％的蜗牛酶作用时间40分钟,0.7MKCl高渗稳定剂的条件下,制备原生质体。两亲株的原生质体形成率分别为98.2％和91.0％。原生质体再生率为6.12％和2.13％。两亲株的原生质体在35％聚乙二醇(PEG, M.W.6000),50mMCaCl_2下诱导融合15分钟,在基本培养基上长出营养互补的融合菌株,融合频率为4.14x10_(-4)。本文就两亲株的原生质体形成和再生条件进行了初步的探讨,并进行了原生质体融合的尝试,     

空间细胞电融合关键技术的地基研究——烟草细胞的电融合

本文针对建立空间细胞电融合技术存在的三个主要问题进行了研究。结果表明,用低温(4℃)、融合介质(0.55 mol/L甘露醇)并添加0.1%纤维素酶保存原生质体,72 h内可以使约94%细胞维持无壁状态,同时并未使细胞丧失再生能力,基本满足从地面制备亲本细胞到在微重力条件下进行电融合,对亲本细胞保持无壁状态的要求。为减少剪切力环境对亲本细胞造成的损伤,一方面用超速离心方法对亲本细胞之一去液泡,另一方面用电泳代替蠕动泵混合亲本细胞。而且,由于原生质体壁生长与其膜电位之间存在负相关性,因此利用电泳方法可以有效地富集和优化亲本细胞。根据地面实验结果推测,空间有/无液泡亲本细胞电融合的较适合参数可能为:交流电场强度90V/cm,频率0.8 MHz,排列时间20 s,直流脉冲1.0—1.3 kV/cm,幅宽40μs,两次脉冲。     

小球藻和莱茵衣藻原生质体的电转化研究

以小球藻及莱茵衣藻原生质体为受体细胞,利用电击法将质粒p CAMBIA1301转入小球藻和莱茵衣藻,摸索电击转化条件并进行分子检测。结果表明:两类藻都对潮霉素敏感,小球藻及莱茵衣藻分别在含25 mg/L和100 mg/L潮霉素的固体培养基上的生长被完全抑制;小球藻和莱茵衣藻原生质体电击转化的最佳电击场强分别为0.8 k V/cm和0.6 k V/cm,最佳脉冲时间均为10 ms;制备原生质体和通过2-脱氧-D-葡萄糖处理可明显提高转化效率;分子检测说明GUS报告基因成功转入两种藻并可稳定遗传。     

坛紫菜和条斑紫菜的原生质体电融合

用日本岛津公司生产的电融合装置(SSH－2),进行了坛紫菜和条斑紫菜的原生质体融合试验。探讨了不同的电刺激条件、融合缓冲液种类以及蛋白酶的前处理与细胞融台的关系。其结果是,高频电压30一35V,印加时间25—30s;脉冲电压300—350V,印加时间60μs,及添加3m mol／L Ca²⁺、Mg²⁺的融合缓冲液可使融台率达到21—31％。蛋白酶的前处理对细胞融合有明显的效果。融合细胞培养7天后产生细胞壁,4l天长成多细胞团。     

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.     

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.     

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