梨远缘花粉原位萌发及生长特性

应用荧光标记方法对梨远缘花粉在‘丰水’和‘噢嗄二十世纪’柱头上萌发及花粉管生长特性进行观察,结果表明:(1)梨远缘花粉均能在柱头上萌发,但其萌发率不同,授粉后24 h,在‘丰水’柱头上‘红叶桃’花粉萌发率最高,达62.8%,而‘盖县大李’花粉萌发率仅为12.0%,各种远缘花粉在‘丰水’柱头萌发率均高于‘噢嗄二十世纪’柱头。(2)各种远缘花粉管在梨柱头或花柱内生长情况也有差异,‘红叶桃’等核果类花粉管在梨柱头上均表现为扭曲、盘绕等现象,不能穿过柱头;‘红星’和‘红富士’花粉管虽然有少量穿过柱头,但不能进一步在花柱内生长,表现为扭曲变形、先端膨大等不亲和性现象。因此,梨与远缘果树杂交不亲和在柱头上就已发生,这与梨自交不亲和反应发生在花柱内的现象不同。     

小毛茛雌蕊群的授粉率及花粉管生长途径

为探讨毛茛属中是否具有与慈姑属中类似的花粉管再分配现象,对小毛茛开花后不同时期柱头的授粉率和花粉量进行了统计,并采用荧光显微术观察了其花粉在雌蕊群中的萌发及花粉管生长过程。该种的每朵花中含有39.2±9.9个离生心皮,开花过程常持续4~6d,开花2d后,柱头授粉率就可达到100%,平均每柱头的花粉量在3d后达到17.0±2.4粒。虽然开花的当天即有少数柱头落置有花粉粒,但花粉萌发常自开花的次日开始。花粉管先沿各雌蕊之向心一侧的组织中穿行至子房基部后部分花粉管转向胚珠,由珠孔进入珠心。从花粉粒落置于柱头到花粉管进入珠心大约需要24h。尽管毛茛属有着与慈姑属类似的多心皮雌蕊群,但大量的荧光显微观察表明,与慈姑属植物中不同的是,小毛茛的花粉管生长均局限于每一雌蕊中而不能穿过子房向其他雌蕊生长。雌蕊群的比较解剖发现野慈姑的子房基部有一条通向花托表面的孔道,这正是花粉管由一个雌蕊到另一个雌蕊的通路,但小毛茛的子房基部不存在此孔道。     

簇枝补血草花的二态性及繁育系统研究

白花丹科被列为异型花柱较多的科,该文以补血草属簇枝补血草为材料,通过对野外居群的花部特征、花期物候和繁育系统等研究,探讨花部形态多态性及其对生殖的影响。簇枝补血草具有两种类型植株,具玉米状柱头和A型花粉的植株称为C型植株;具乳头状柱头和B型花粉的植株称为P型植株,且A/B型花粉的大小、外壁纹饰不同。单花发育过程中两型植株的花萼、雌蕊大小差异明显,随着花的成熟差异逐渐消失。两型植株都为雌蕊高于雄蕊,柱头探出式雌雄异位;C型植株的花期较P型植株长约2 d。一天当中,A型花粉活力高峰期为13:00,B型花粉在11:00和15:00都表现为高峰期;玉米状柱头可授性最强时期在13:00～15:00,乳头状柱头则在15:00。两型花粉可育性在盛花期最高,终花期时B型花粉可育性明显高于A型。荧光染色观察发现花粉萌发和花粉管的生长速度都为:异型授粉＞同型授粉,B型花粉在乳头状柱头上不能完成受精。此外,人工授粉实验也表明异型授粉结实率显著高于同型,P型植株经同型授粉结实现象并不明显,存在少量无融合生殖。研究表明簇枝补血草花部具二态性,繁育系统为兼性异交,其中乳头状柱头对A型花粉亲和,对B型花粉不亲和,但玉米状柱头却对A/B型花粉都亲和,这打破了该科的异型自交不亲和的例证。     

野菊与菊花杂交中花粉活力和柱头可授性及胚胎发育研究

应用石蜡制片、活体压片、光学显微镜及扫描电子显微镜观察等方法,研究了四倍体河南云台山野菊(Dendranthema indicum)与栽培菊花'钟山金山'(D.grandiflorum 'Zhongshanjinshan')种间杂交中父本花粉活力、花粉在柱头萌发、花粉管生长及胚胎发育情况等.结果发现,父本云台山野菊的花粉活力在授粉时为12%左右.人工授粉后的不同时间,在柱头上都观察到正常萌发的花粉粒,且花粉管都能进入柱头,其中,在授粉后0.5 h时,平均每柱头有5.9粒花粉萌发;12 h时,为59.9粒;而24和48 h时,则分别降为47.1和35.7粒.此外,在授粉后8、10、12和15 d时,分别在49.1%、40.8%、39.7%和38.5%子房内观察到正常发育的胚胎,最终杂交结实率为44.8%,而母本自然开放结实率为52.3%.研究表明,授粉前其多数母本雌蕊发育良好、授粉后多数花粉能在柱头正常萌发和花粉管正常生长,在受精后大部分胚胎发育正常是野菊与栽培菊种间杂交较高结实率的重要保证,而授粉前父本较低的花粉活力对杂交结实率影响不大.     

授粉对水稻柱头蛋白质合成及钙离子富集的影响

应用非平衡等电聚焦和双向电泳技术,在不同水稻品种开花前后发育早期的雌蕊柱头中,发现两类5种电泳特性相似的主要多肽;在自交或杂交亲和授粉后并无明显变化;而在杂交不亲和授粉后,柱头中出现分子量为17．5kD,等电点为8．5的新带,可能与杂交不亲和授粉后的识别反应有关。在成熟柱头表面有大量钙离子富集,在幼嫩柱头表面却未发现;用成熟花粉强迫自交授粉,可诱导钙离子在幼嫩柱头表膜富集,说明钙离子的富集不但与柱头的成熟而且也与花粉的接触有关。     

青篱柴通过促进亲和花粉生长而提高传粉精确性

异型花柱植物的适应意义在于提高亲和花粉的传递, 从而促进异交, 但是有不少研究发现柱头上落置了大量不亲和花粉。目前, 很少有人研究柱头是否有利于亲和花粉的萌发和花粉管伸长, 以及通过去雄处理排除花内和植株内不亲和花粉干扰从而验证二型花柱植物是否可以促进异交。本研究以亚麻科青篱柴属(Tirpitzia)的二型花柱植物青篱柴(T. sinensis)为研究对象, 分居群调查了青篱柴长、短柱型的植株数量, 测量不同柱型的花粉与柱头大小以及观察其表面纹饰, 测定不同开花时间长、短柱型的柱头活性与花粉活力, 统计自然状态下柱头上落置的不同表型花粉比例, 进一步统计花内、株内去雄和自然对照下柱头上落置的不同表型花粉比例, 计算型间、型内和混合授粉花粉管长度和花粉萌发率, 人工授粉检测其是否型内异交不亲和与自交不亲和。结果表明, 自然居群中长、短柱型青篱柴植株数量没有显著性差异; 短柱型青篱柴花粉体积显著大于长柱型, 且二者花粉表面纹饰不同, 但不同柱型的柱头表面积与表面纹饰无差异; 青篱柴开花第一天的花粉活力显著高于开花第二天, 而柱头活性在开花前两天无显著性差异; 自然状态下柱头上落置的不亲和花粉比例显著高于亲和花粉; 在长柱型青篱柴中, 花内和株内去雄显著提高了柱头上亲和花粉的落置比例; 柱头上授型内花粉, 其花粉萌发率和花粉管的长度都显著低于授型间花粉; 授粉结果表明青篱柴为型内异交不亲和与自交不亲和。二型花柱植物通过促进亲和花粉的萌发和花粉管的伸长而有利于型间授粉, 从而显著提高其传粉精确性。     

花粉——雌蕊相互作用的分子基础

显花植物授粉过程包含了花粉与雌蕊一系列复杂的细胞间相互作用。花粉在柱头上必须发生粘附与水合作用后才能萌发,花粉胞被蛋白可能在粘附机制中起主要作用,而水孔蛋白调节了花粉的水合过程;花粉管在花柱引导组织中定向生长,受引导组织胞间质、向化性物质及细胞粘附机制等因素的影响,也与花粉受体及子房有关。在植物的自交不亲和性反应中,配子体型自交不亲和性反应主要是由自交不亲和基因蛋白产物降解花粉RNA或以Ca^2 介导的信号级联反应实现的;孢子体型自交不亲和性反应则依赖于干性柱头以及雌蕊的S受体激酶及S位点糖蛋白与花粉S基因配体之间的相互作用。     

鸡蛋花不育机理初步研究

本文探索鸡蛋花开花不结实的原因。通过对鸡蛋花雌、雄性器官的切片观察和离体花粉萌发,发现其花粉和胚囊均正常,离体花粉可萌发花粉管;但鸡蛋花的花筒长约1 cm,花筒基部湿度较高;开花时,雌蕊柱头和雄蕊花药均不能伸出花筒,花药不能开裂释放花粉,产生了传粉障碍,最终导致不育。     

三种耧斗菜属植物柱头的特征

为了深入了解植物捕获花粉的机制和生殖策略,我们对3种耧斗菜属Aquilegia L.植物华北耧斗菜A. yabeana Kitagawa、无距耧斗菜A. ecalcarata Maxim.和秦岭耧斗菜A. incurvata P. K. Hsiao的雌蕊进行了扫描电镜和荧光显微镜观察,发现其柱头发育的特殊式样。其柱头位于花柱的腹缝面,由花柱腹缝两侧细胞发育成柱头乳突,在花期中从顶端朝花柱基部渐次成熟。伴随花柱向外弯曲,成熟的柱头表面相继呈现,逐渐增加了花粉落置的空间。这种柱头发育的式样通过延长柱头的可授期,增加了植物在不可预测的传粉环境下的繁殖机会。     

花粉求亲记

白的,黄的,粉的,红的……一只小蜜蜂吮吸过无数花朵的甜蜜,携带着无数粒花粉,飞到一朵苹果花上给这些花粉求亲。接下来就是,一部分幸运的花粉被苹果的雌蕊柱头所接受,在阳光的照耀和雨露的滋润下,它开始萌发并长出花粉管,花粉管一点点伸长,到达雌蕊的胚珠,最终在这里完成了受精作用,在不远的将来,一个小苹果就要诞生了。     

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.     

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     

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.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.     

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).