小麦小孢子发生过程的超微结构

采用透镜电镜技术对小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ）小孢子发生过程进行了超微结构观察。造孢细胞时期细胞质中含有丰富的核糖体,质体和线粒体。在小孢子母细胞减数分裂过程中,有核糖体数量存在逐渐减少的现象,质体和线袜体结构在双线期／终变期和中期１简化,二分体时期,质体和线粒体形态结构基本恢复正常。结果表明,啵麦小孢子母细胞减数分裂过程中存在质体和线粒体的脱人化与再分化过程,但该过程与核糖体数量增     

枸杞花粉发育的超微结构变化

用JEM-100CXⅡ透射电子显微镜对宁夏枸杞(Ly cium barbarum L.)花粉发育过程做了超微结构观察.结果表明,在花粉母细胞细线和偶线期,核糖体数量减少、线粒体结构简化;之后核糖体数量逐渐回升,后期Ⅰ线粒体结构恢复正常.小孢子液泡化过程中核糖体再次减少,同时线粒体和质体结构简化;在早期二胞花粉中,核糖体数量增加、线粒体和质体结构再度分化.花粉母细胞和小孢子发育过程中都存在“细胞质改组”现象,且这两次“细胞质改组”与细胞功能的转变密切相关.在次生造孢细胞、花粉母细胞和小孢子后期都有液泡数量明显增加或体积增大的过程.前两次液泡的增加可能参与了其胼胝质壁的构建;而小孢子晚期中的大液泡则创造了一种极性为其不等分裂作好了生理和结构上的准备.     

棉花小孢子发生过程中细胞质的超微结构变化：着重“细胞质改组”问题

棉花(Gossypium hirsutum L.)小孢子发生过程中,细胞质超微结构发生显著而有规律的变化。这些变化主要涉及细胞质中核糖体、质体和线粒体。减数分裂前期Ⅰ,细胞质中核糖体密度逐渐降低,质体和线粒体结构变得不明显。粗线期至双线期,细胞质中核糖体密度降至极低水平,同时质体和线粒体呈衰退结构状态。中期Ⅰ,细胞质中核糖体恢复致密,质体和线粒体也恢复了正常的形态和结构。来自细胞核的类核仁进入细胞质并扩散。这是恢复中期Ⅰ细胞质中核糖体密度的主要原因。内质网在核糖体数量变化中显示出有重要作用。这些细胞质超微结构的变化可认为与世代转变有关。     

牡丹小孢子发生与雄配子体发育的超微结构研究

牡丹（Paeonia suffruticosa Andr.）花粉母细胞在减数分裂前期Ⅰ出现核液泡,其具有消化和转移细胞核中降解产物的功能。细胞发生了规律性的变化：前期Ⅰ,核糖体数量减少,质体、线粒体结构简化;末期Ⅰ和前期Ⅱ,出现细胞器带,四分体时期,细胞器分散开,结构较清晰,核糖体密度最大。小孢子时期,各结构简化,数量减少,至成熟二胞花粉时,细胞器丰富,结构恢复清晰。牡丹生殖细胞初期具壁,游离在营养细胞质内后壁消失,始终不含质体。花粉成熟时,生殖细胞和营养构成“雄性生殖单位“（MGU）。     

栽培甜菜花粉发育过程的超微结构

利用透射电镜技术对栽培甜菜(Beta vulgaris)花粉发育过程进行了超微结构观察。结果表明, 在小孢子母细胞减数分裂期间, 细胞内发生了“细胞质改组”, 主要表现在核糖体减少, 质体和线粒体结构发生了规律性变化。末期I 不形成细胞板,而是在2个子核间形成“细胞器带”。“细胞器带”的存在起到类似细胞板的作用, 暂时将细胞质分隔成两部分。四分体呈四面体型, 被胼胝质壁包围。小孢子外壁的沉积始于四分体晚期, 至小孢子晚期外壁已基本发育完全。单核小孢子时期, 细胞核大, 细胞器丰富。二细胞花粉发育主要表现在生殖细胞壁的变化上, 生殖细胞壁上不具有胞间连丝。成熟花粉为三细胞型, 含有1个营养细胞和2个精细胞。精细胞具有短尾突, 无壁, 为裸细胞, 每个精细胞通过2层质膜与营养细胞的细胞质分开。生殖细胞与精细胞里缺乏质体。     

栽培甜菜花粉发育过程的超微结构

利用透射电镜技术对栽培甜菜（Beta vuigaris）花粉发育过程进行了超微结构观察。结果表明,在小孢子母细胞减数分裂期间,细胞内发生了“细胞质改组”,主要表现在核糖体减少,质体和线粒体结构发生了规律性变化。末期1不形成细胞板,而是在2个子核间形成“细胞器带”。“细胞器带”的存在起到类似细胞板的作用,暂时将细胞质分隔成两部分。四分体呈四面体型,被胼胝质壁包围。小孢子外壁的沉积始于四分体晚期,至小孢子晚期外壁已基本发育完全。单核小孢子时期,细胞核大,细胞器丰富。二细胞花粉发育主要表现在生殖细胞壁的变化上,生殖细胞壁上不具有胞间连丝。成熟花粉为三细胞型,含有1个营养细胞和2个精细胞。精细胞具有短尾突,无壁,为裸细胞,每个精细胞通过2层质膜与营养细胞的细胞质分开。生殖细胞与精细胞里缺乏质体。     

油松细胞质遗传的细胞学机理:Ⅱ.雄性和雌性细胞器在受精和原胚时期的传递(英文)

在电镜下观察油松 (PinustabulaeformisCarr.)传粉后的胚珠临近受精时的花粉管和卵细胞的细胞质、受精时雄配子体细胞质的传递、游离核和细胞原胚发育时期质体和线粒体的传递。在成熟卵细胞中含许多线粒体 ,缺少正常结构的质体 ,它们转变为大内含体。此外 ,卵细胞还有丰富的小内含体和其他一些细胞器。花粉管在卵细胞的珠孔端释放其内含物。精核与卵核融合时 ,核周围未见来自精细胞的质体和线粒体。不参与融合的精核停留在接受液泡旁 ,在其周围有大量的雄性细胞质 ,其中混合有精细胞、管细胞和卵细胞的细胞器。在游离核原胚时期 ,核周区的细胞质中可见雄性与雌性亲本的细胞器相混合 ;其中许多线粒体与原来卵细胞中的线粒体有相同的形态 ,也有一些线粒体看来是来自精细胞和管细胞 ;质体是由雄配子体传递 ,形态与精细胞的或花粉管中的质体相似。卵细胞中变异的质体 (即大内含体 )在原胚发育时期变为液泡状 ,而雄性质体参加到新细胞质中。在原胚细胞中 ,线粒体大多数为母本来源 ,质体则表现为精细胞或管细胞的质体形态。该研究确定了油松具父系质体和双亲线粒体遗传的细胞学基础。对裸子植物线粒体和质体遗传的机理从细胞学的角度进行了分析。     

同源四倍体水稻小孢子发生的超微结构

利用透射电子显微镜对同源四倍体水稻小孢子母细胞减数分裂前及期间的超微结构进行观察,结果发现:(1)减数分裂前及减数分裂早期,小孢子母细胞核糖体密度高,线粒体、质体等细胞器丰富;粗线期核糖体密度显著下降,线粒体、质体等细胞器数量减少;终变期核糖体密度逐渐恢复到减数分裂前状态,而其他细胞器的数量除在二分体时期出现短暂的回升,终变期以后的时期均较少.(2)小孢子母细胞间的连接在小孢子母细胞时期以典型的胞间连丝为主,进入细线期,胞间连丝数量显著减少,宽孔道的胞质通道逐渐增多,粗线期小孢子母细胞间基本通过胞质通道连接,终变期小孢子母细胞间完全分离.(3)随着减数分裂的进行,药壁四层细胞逐渐液泡化,绒毡层细胞中部分小液泡融合成大液泡,形成胞内"空腔";药室内壁细胞出现大量的具有叶绿体结构特征的质体,内含丰富的淀粉粒,到了四分体时期质体数量及内含的淀粉粒显著减少.     

植物小孢子母细胞胞间细胞融合通道的超显微结构研究

采用常规的透射电子显微镜术研究了百合和黑麦花药小孢子母细胞减数第一次分裂前期孢间细胞融合道（ＩＣＣ）的精细结构。首次发现ＩＣＣｓ内部除包含早期研究所看到的染色质,或核糖体、质体、线粒体等细胞器外,其中还存在有一些形态学特征与微丝和微管类似的细胞骨架系统。该系统穿过ＩＣＣｓ,从一个细胞延伸到相邻细胞的细胞质内,表面与周围的染色质颗粒、核糖体、质体等细胞器相连,方向与细胞质或核物质细胞间运动的方向一致     

西瓜小孢子发育过程中几种细胞器的变化

用透射电子显微镜观察了西瓜（Ｃｉｔｒｕｌｌｕｓ ｖｕｌｇａｒｉｓ Ｓｃｈｒａｄ．）小孢子发育过程中核糖体、线粒体、质体、内质网、高尔基体等细胞器的变化。核糖体和线粒体变化都有明显的规律性：核糖体密度在四分体时期高,液泡化时期降低,液泡化结束后再回升;线粒体经历一个脱分化与再分化周期,液泡化时期该细胞器数量及其内嵴数目减少而脱分化,液泡化结束后形状多样化、内嵴重新增多而再分化;质体结构不变,但体积变     

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.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

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).     

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.