重口裂腹鱼眼早期形态发生研究

采用组织学方法观察了实验室饲养的重口裂腹鱼眼在胚胎和早期仔鱼阶段的发生和形态变化过程。结果显示,重口裂腹鱼眼的发生开始于神经胚时期形成的眼原基,眼原基经过分化和内陷形成双层视杯,最终发育形成视网膜。晶状体和角膜来源于外胚层细胞,晶状体发育主要经历晶体板时期;角膜的发育时间较视网膜和晶状体晚,始于角膜上皮的形成。出膜后3 d仔鱼视网膜发育基本完成,眼色素沉积明显,基本具备眼的功能结构。本研究结果丰富了重口裂腹鱼早期发育的生物学资料,为苗种培育等生产实践提供了理论指导。     

非洲爪蟾眼的形态发生研究

详细观察和描述了非洲爪蟾Xenopus laevis眼的发生和发育变化过程,并分别对各发育时期视网膜的厚度进行了定量分析.非洲爪蟾眼的发牛开始于眼原基的形成,进而形成视泡;晶状体的发生是在视杯外壁增厚的同时诱导覆盖其上的胚胎外胚层内层增厚,形成预定晶状体板;在视网膜和晶状体共同诱导下,预定角膜上皮变为透明的角膜.在视杯出现之前,预定RPE的厚度由厚变薄,NR层不断地增厚直至结构功能完善.     

河川沙塘鳢视觉器官的发育及其与摄食的关系

利用光学显微镜观察了河川沙塘鳢(Odontobutis potamophila)视觉器官的发育,并对其发育与摄食的关系进行了研究。河川沙塘鳢的眼囊起源于神经外胚层。当胚胎发育至心跳期时,眼囊内陷形成视杯;之后,视杯内表面的外胚层形成晶状体而与视杯分离,视杯进一步发育形成视网膜。随着胚胎的进一步发育,晶状体的直径增加,结构逐步发育完善。胚胎发育至眼黑色素出现期时,视网膜分化为6层,其中,外核层、内核层和神经节细胞层3个核层明显;胚胎发育至孵化前期时,视网膜已分化为10层。孵出后1d的仔鱼,其视网膜已能行使功能,仔鱼逐渐开口摄食。随着稚、幼鱼的发育,视网膜厚度进一步增加,结构发育完善。视网膜的结构和视觉特性显示河川沙塘鳢是要求光照条件好、白昼活动并具有较好视觉功能的鱼类。     

胭脂鱼眼早期形态发生研究

采用组织学方法观察了胭脂鱼(Myxocyprinus asiaticus) 眼的发生过程, 结果显示: 胭脂鱼眼的发育经历了眼原基形成期、眼囊形成期、视杯形成期、晶体板形成期、晶体囊形成期、角膜原基形成期、角膜上皮形成期、视网膜细胞增殖期、晶状体成熟期、眼色素形成期以及眼成型期等11个时期。视网膜发育最早, 起始于眼原基的形成, 直至眼成型期分化完成, 形成了厚度不一的8层细胞, 由内向外依次为神经纤维层、神经细胞层、内网层、内核层、外网层、外核层、视杆视锥层和色素上皮层, 且发育历时最长, 约264h。晶状体的发育在视网膜之后, 始于晶体板的形成, 于出膜前期成熟, 发育历时最短, 约74h。角膜发育最晚, 始于角膜原基的形成, 出膜1 d分化为透明的成熟角膜, 发育历时约96h。出膜4 d仔鱼眼色素沉积明显, 视网膜各层分化明显, 晶状体内部完全纤维化, 眼的形态结构基本发育完全。     

稀有鮈鲫眼的形态发生研究

详细观察和描述了稀有鮈鲫眼发育的形态变化,并分别对视网膜发育早期神经层、色素上皮层的厚度及眼发育后期视网膜的总厚度进行了测量。结果表明:稀有鲫眼的发生始于神经胚时期形成的眼原基,与两栖、哺乳类动物不同,其眼原基是由间脑向左右伸出的对称外突实体;在尾芽期眼原基向腹侧弯曲、侧向伸长,随后开始内陷,在尾泡期形成视杯。眼原基外层与外胚层紧贴的部分将发育为视杯的内层、神经视网膜,而眼原基其余部分将分化为视杯的外层、视网膜色素层。在尾泡期之后,视网膜色素层停止有丝分裂开始形成色素颗粒,此时视网膜神经层开始分化。视网膜这两层结构在发育早期分化的有序进行可能与早期胚胎头部内空间以及附近的间充质细胞有关。从神经胚期到尾泡期,视网膜色素层厚度由42.3±0.8μm减小到4.8±0.4μm,视网膜神经层厚度从37.1±0.2μm增加到43.7±0.6μm,而从尾鳍期到孵出期视网膜总厚度从42.7±1.2μm逐渐增加到98.3±2.1μm。与所有脊椎动物一样,稀有鲫眼的视网膜分化也是按照由内向外的顺序进行,晶状体、角膜及其他结构在孵出时已基本发育完全。     

胚后64小时龄和35天龄大熊猫视网膜的显微结构

为了解大熊猫眼睛的胚后发育状况,对６４小时龄和３５天龄大熊猫视网膜的组织结构进行了观察,发现胚后６４小时龄大熊猫视网膜的分化程度很低,色素层已形成,但视泡腔明显;神经层由外面数层长梭形,内面数层圆形细胞核及无核的纤维层构成。     

褐菖鲉的视觉器官发育

为研究褐菖鲉（Sebastiscus marmoratus）视觉器官发育与生态习性及摄食行为之间的关系,用组织学方法对人工培育条件下的褐菖鲉仔、稚鱼的视觉器官发育特征进行了详细观察。结果表明,褐菖鲉为卵胎生鱼类,其视觉器官的分化速度较一般鱼类快,从母体产出时,仔鱼视网膜神经细胞层和原始晶状体已形成;1日龄仔鱼的视网膜分化为6层,晶状体出现纤维化,直径约72 μm,仔鱼开始具有一定趋光性;2日龄仔鱼视网膜分化完成,可见10层结构,巩膜出现,与仔鱼开口摄食相适应,游泳能力增强;5 ~ 7日龄晶状体直径达99 μm,晶状囊形成;17日龄,仔鱼角膜结构分化完成,脉络膜趋于完善;37日龄稚鱼的视觉器官各部分已经发育完全。     

扬子鳄胚胎中脑视叶的组织发生

观察了16例不同时间扬子鳄胚胎中脑视叶的组织发生过程。胚胎孵育第6d,三个脑泡明显;孵育第9～10d,中脑泡可分细胞层和边缘层或纤维层,中脑水管未形成;孵育第18d,视叶隆起于中脑背侧,中脑水管形成,视叶分三层;孵育第24d,视叶分5层;孵育第34d,视叶分化为6层;孵育第51d,视叶分化为8层,与初生扬子鳄中脑视叶分层相同。     

Vax基因与视觉神经系统的早期发育

视觉神经系统的发育与形成是一个相当复杂的过程,其基因调控机理是神经发育生物学领域的研究热点.Vax基因家族是新近发现的一类与视觉神经系统发育密切相关的同源异型盒基因,调控前脑、眼原基、视泡、视柄以及视网膜的发育.Vax-1参与色素上皮和视柄的分化;Vax-2则在视网膜及视神经背腹轴建立方面起重要作用.Vax基因的研究将对阐明视觉神经系统发育调控机制提供新的认识.     

花背蟾蜍眼早期形态发生中其主要部分空间联系的研究

本文用扫描电镜研究了花背蟾蜍眼早期形态发生中视泡和预定晶状体、晶状体和预定角膜上皮间的紧密接触,此后在接触处出现间隙,其中存在呈网状的原纤维(fibril),这些原纤维的数量随两侧相连组织的分化,表现出增多、减少和逐渐消失的规律性变化,据此推测其成分属细胞外基质,对促进相连组织的分化起重要作用。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.