春小麦早期胚胎发育进程及细胞融合(cytomixis)的观察

观察了小麦胚和胚乳初期的发育进程,得到如下结果:授粉后2小时,二个精子已分别进入卵核和极核;6小时,极核已经完成受精,卵核与另一精子的融合正在进行。授粉后24小时为二细胞原胚,6天时部分胚胎开始分化。授粉后3天,胚乳核开始形成细胞,至6天时,胚乳细胞充满胚囊。开花前充分发育的反足细胞授粉后开始解体,第4天已失去细胞结构,仅留下核仁和染色质团块,第8天几乎完全消失。在珠心、胚乳、子房壁和原胚以及分化胚的胚柄中都观察到细胞融合现象,而且在原胚附近出现较多。     

白桦雌花发育、大孢子发生及胚胎发育的解剖学观察

白桦雌花从开花到雌性器官的成熟需经历1个月左右的时间,解剖学观察表明：四月下旬越冬的雌蕊原基开始了活跃的分裂和分化。子房和柱头开始生长。四月末开花,五月初授粉。此后胚珠开始长大。五月中旬即分化形成珠被,珠心,珠被为单层珠被,胚珠为厚珠心胚珠,胚珠倒生,五月中下旬,珠心内产生大孢子母细胞,一周左右发育为成熟胚囊-七细胞八核胚囊,五月末完成双受精,白桦胚胎发育经过合子,原胚,球形胚,心形胚和鱼雷形胚等时期最后发育成熟,胚乳发育与胚胎同步,即受精的极核进行几次分裂后形成核型胚乳,胚乳核不断增多,在形成心形胚后胚乳细胞形成细胞壁。     

丫蕊花的双受精及胚和胚乳发育的初步观察

丫蕊花（Ypsilandra thibetica Franch.)为珠孔受精,进入胚囊的两个精子分别与卵细胞和中央细胞进行正常的双受精,其受精作用属有丝分裂前型,受精后的初生胚乳核立即分裂,其发育方式为沼生目型,到发育后期,由游离状态的胚乳核形成胚乳细胞时,珠孔室和合点室都形成胚乳细胞,合子的休眠期很长,而且胚的发育过程较为缓慢,种子成熟时胚尚无器盲的分化,本文还观察了以上发育过程中淀粉粒,蛋白质的动态。     

丫蕊花的双受精及胚和胚乳发育的初步观察

丫蕊花（Ypsilandra thibetica Franch.)为珠孔受精,进入胚囊的两个精子分别与卵细胞和中央细胞进行正常的双受精,其受精作用属有丝分裂前型,受精后的初生胚乳核立即分裂,其发育方式为沼生目型,到发育后期,由游离状态的胚乳核形成胚乳细胞时,珠孔室和合点室都形成胚乳细胞,合子的休眠期很长,而且胚的发育过程较为缓慢,种子成熟时胚尚无器盲的分化,本文还观察了以上发育过程中淀粉粒,蛋白质的动态。     

毛竹种子形成过程中形态解剖学特征

为揭示毛竹(Phyllostachys edulis)种子生长过程中胚、胚乳、果皮及种皮的发育规律,以桂林海洋山一带的开花毛竹为材料,采集并固定不同时期的开花毛竹种子,使用石蜡制片法制片,显微镜观察胚、胚乳、果皮与种皮的结构变化。结果表明：(1)毛竹花后1 d完成受精并形成合子,合子休眠时长约为5 d。经过原胚阶段、胚芽鞘阶段、幼胚生长阶段及成熟胚阶段,花后40 d的胚发育基本成熟,其发育类型为禾本型。(2)胚乳发育早于胚的发育,其发育类型为核型胚乳,历经游离核、细胞化、细胞分化及成熟4个阶段。在细胞分化阶段胚乳细胞分化形成淀粉胚乳细胞以及糊粉层细胞,淀粉胚乳细胞主要积累淀粉粒,糊粉层细胞主要积累矿质元素、脂类及蛋白质等。(3)花后1 d的果皮细胞及珠被细胞形状规则、内含物丰富、结构完整;花后10～20 d,内、外果皮及珠被细胞层数递减,形状发生改变,中果皮细胞开始出现淀粉粒;花后20～60 d,随着胚乳细胞营养物质的积累及体积的增大,向外产生机械压力,中果皮细胞逐步消解仅剩残留的细胞壁;外果皮细胞呈长条形,细胞壁加厚,与残留的中果皮细胞壁组成保护结构;皮层在种子发育过程中主要起到合成...     

刺五加胚和胚乳发育的研究

刺五加Eleutherococcus senticosus(Rupr .et Maxim．)Maxim的胚胎发生类型为茄型。其卵细胞受精后,合子经历15天左右的休眠期才进行第一次分裂。合子分裂通常发生在胚乳细胞化之后,经棒形胚、球形胚、至果实成熟时发育到心形胚。棒形胚后期至心形胚初期,胚柄最为发达。刺五加的胚乳发育类型为核型。其初生胚乳核的休眠期为1天左右。当胚乳游离核数目增加到200至300时,胚乳以自由生长细胞壁的方式细胞化,胚乳细胞以典型的有丝分裂方式进一步增殖,增加细胞数目。球形胚时期,胚乳细胞内开始贮藏营养物质。少数种子的胚乳里存在巨大细胞核的异型胚乳细胞。在胚乳游离核为32至64个时,分化出珠被绒毡层;球形胚时期,珠被绒毡层解体。珠被绒毡层解体后,胚乳表层细胞分化为分泌层。球形胚至心形胚阶段,约有5％的种子里,胚与胚乳组织发生弥散样降解。成熟果实中,含有大量的瘪粒种子和虫咬种子;饱满种子率为40％左右。饱满种子中,胚乳组织占据种子体积的绝大部分,胚所占比率很小。讨论了不同发育时期胚和胚乳的营养供应。     

甘薯胚胎及果实发育的研究

本文研究甘薯的胚胎发育及果实的形成。授粉后10—30分钟花粉粒在柱头上萌发,2小时花粉管抵达珠孔,5—12小时左右完成双受精。授粉后12小时胚乳核开始第一次有丝分裂;15小时合子开始第一次有丝分裂,18小时形成顶细胞和基细胞;尔后分化成原胚,球形胚,心形胚,鱼雷形胚,成熟胚。在适宜温度下21天左右胚胎发育完成。果为蒴果,其内含有1—4粒种子。授粉后3—4天子房开始膨大形成果实,21—30天蒴果与种子成熟。     

萝卜胚胎早期发育的亚显微结构研究

本研究对萝卜（Raphanus sativus L.)的成熟胚囊,胚和胚乳的早期发育过程作了亚显微结构观察：（1）萝卜胚囊由7个细胞组成,成熟时反足细胞消失;（2）卵细胞表现明显的极性,其合点端不具完整的细胞壁,它是电子致密物质在卵细胞和中央细胞两者质膜之间沉积所形成的一种非连续结构。（3）助细胞的明显特点是具丝状器,细胞器丰富,内质网发达,（4）中央细胞具大液泡,它的两个极核位于靠近卵器的一侧,细胞壁也有类似助细胞丝状器的结构。（5）授粉后4－5天,萝卜合子开始第一次分裂,胚胎发育遵循柳叶菜型模式。（6）萝卜初生胚乳核比合子早约2天分裂,属核型胚乳,在胚囊的合点端和珠孔端,曾出现胚乳的结节状聚集,授粉后第16天左右,从珠孔区胚乳开始了细胞壁自由生长和形成胚乳细胞的过程。     

萝卜胚胎早期发育的亚显微结构研究

本研究对萝卜（Raphanus sativus L.)的成熟胚囊,胚和胚乳的早期发育过程作了亚显微结构观察：（1）萝卜胚囊由7个细胞组成,成熟时反足细胞消失;（2）卵细胞表现明显的极性,其合点端不具完整的细胞壁,它是电子致密物质在卵细胞和中央细胞两者质膜之间沉积所形成的一种非连续结构。（3）助细胞的明显特点是具丝状器,细胞器丰富,内质网发达,（4）中央细胞具大液泡,它的两个极核位于靠近卵器的一侧,细胞壁也有类似助细胞丝状器的结构。（5）授粉后4－5天,萝卜合子开始第一次分裂,胚胎发育遵循柳叶菜型模式。（6）萝卜初生胚乳核比合子早约2天分裂,属核型胚乳,在胚囊的合点端和珠孔端,曾出现胚乳的结节状聚集,授粉后第16天左右,从珠孔区胚乳开始了细胞壁自由生长和形成胚乳细胞的过程。     

长豇豆胚和胚乳的发育及营养物质积累

长豇豆(Vigna sesquipedalis (L.)Fruwirth)开花前7—10小时传粉,开花后8—10小时完成双受精。合子期珠孔端及合点部位胚囊的周界壁有壁内突。胚发育属柳叶菜型。胚柄的基部细胞及基部区域外层细胞的外切向壁发生壁内突。成熟胚中胚柄宿存。开花后9—16天为子叶细胞中淀粉积累期,开花后12—18天为蛋白质积累期。胚乳发育为核型,珠孔端胚乳细胞化,合点端保持游离核状态。胚乳外层细胞为传递型细胞,珠孔端的胚乳细胞形成折叠细胞群,亦有壁内突。心形胚期胚乳开始退化解体,成熟胚期胚乳完全消失。     

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.     

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