新米斯(竹蜓)(Neomisellina)旋壁超微构造的研究

电子显微镜研究表明，Ｎｅｏｍｉｓｅｌｌｉｎａ的旋壁由致密层和很厚的蜂巢层组成，无内疏松层。致密层由近等轴细小晶粒无定向排列而成，为原生构造，蜂巢层早期由近等轴大晶粒，渐渐为粗大的短柱状晶粒替代，下端由近等轴晶粒与短柱状晶粒混杂规则排列而成。     

䗴类旋壁超微构造的研究——以麦䗴型旋壁为例*

光学显微镜下的观察表明蜓类的旋壁属于钙质微粒壳类型,对它们的电镜观察揭示的组成旋壁的晶粒的大小、形态和排列方式。对具有致密层和蜂巢层型两层式旋壁的Ｔｒｉｔｉｃｉｔｅｓ的电镜研究表明：其致密层由近等轴晶无定向排列而成;蜂巢层由短柱状晶向排列组成板状复合体,进而组合成管状孔,镶嵌在不定向排列的近等轴晶基质中构成。Ｐｓｅｕｄｏｆｕｓｕｌｉｎａ的致密层也由近等轴晶不定向排列构成,蜂巢层由粗柱晶定向排列组成     

(蜓)类旋壁超微构造的研究——以麦(蜓)型旋壁为例

光学显微镜下的观察表明(蜒)类的旋壁属于钙质微粒壳类型,对它们的电镜观察揭示了组成旋壁的晶粒的大小、形态和排列方式.对具有致密层和蜂巢层型两层式旋壁的Triticites的电镜研究表明:其致密层由近等轴晶无定向排列而成;蜂巢层由短柱状晶定向排列组成板状复合体,进而组合成管状孔,镶嵌在不定向排列的近等轴品基质中构成.Pseudofusulina的致密层也由近等轴晶不定向排列构成,蜂巢层由粗柱晶定向排列组成纤状复合体,进而形成管状孔,镶嵌在近等轴晶基质中.     

ting类旋壁超微构造的研究

电子显微镜下观察表明,除史塔夫ting类外,ting类旋壁有8种类型,各分层的超微构造是由开头不同、粒径不一及排列方式各异的方解石晶粒组成。旋壁基本结构包括致密层、透明层、内疏松层、原蜂巢层（?原始层）、蜂巢层及后透明层。ting类标本受后期次生作用,可改变组成旋壁的方解石晶粒原有的形状,晶粒被重结晶,但其旋壁的分层结构仍保留原生的特征。     

(竹蜓)类旋壁钟乳层的研究及新属种

本文研究了(竹蜓)类的一种新型旋壁构造:钟乳层。钟乳层类似于蜂巢层,其不同点在于它的所谓蜂巢孔(壁)的末端往往明显加粗、固结,有时长短不等地向下延伸,表面看来类似副膈壁的形态。 具有钟乳层构造的旋壁由三层或两层组成。三层者由上而下可分为:很薄的致密层,其下为细小而密集的蜂巢层,再往下则由较粗(往往由数条蜂巢孔壁合并而来)并在下端膨大、固结的钟乳层组成。二层者缺失中间的细蜂巢层而直接由致密层与钟乳层组成。前者称复钟乳层,后者称单钟乳层。 钟乳层可能起源于蜂巢层。其主要依据是;1)形态上类似;2)不少标本的内、外圈旋壁构造表明,内圈为明显的蜂巢层,而到外圈则变为钟乳层。从个体发育中的重演现象可知是蜂巢层演变为钟乳层。3)钟乳层最初出现于二叠纪,晚于蜂巢层。至于它是否会演变为副隔壁,目前尚无直接的证据。 本文根据内蒙古、山西的丰富材料建立了2新属,即Taiyuanella gen.nov.和Linxinella gen.nov.,共计10个新种(含2个未定种)。     

Quasifusulina的旋壁构造及其在(竹蜓)类分类、演化中的意义

本文介绍作者利用扫描电子显微镜对(竹蜓)类Quasifusulina旋壁超微构造的初步研究结果。电镜观察表明,Quasifusulina旋壁的主要部分系由许多近等轴的方解石微粒构成,这些微粒有规律地叠置在一起,形成了一系列垂直于壳表、彼此相邻的方解石复合体。尽管其光学特征与蜂巢层和透明层颇为相似,但从构成旋壁的方解石微粒的形状、大小及排列和定向方式来看,Quasifusulina旋壁的超微构造既明显地有别于典型的蜂巢层,也不同于典型的透明层。为便于描述,作者建议将Quasifusulina旋壁的这种特殊构造称为“原蜂巢层”(prokeriotheca)。 根据电镜观察,Quasifusulina旋壁由原蜂巢层及不连续的内疏松层构成,它可能代表了?类有孔虫中一种独特的旋壁类型。这种旋壁构造在?类动物的分类及演化研究中可能具有重要意义。     

白鲟消化道形态学与组织学的初步观察

白鲟消化道具有肉食性鱼类的典型特征,其口咽腔结构既适合捕食又适合吞食与滤食水生动物。咽后消化道可分为食道、胃后行支、胃前行支、小肠、瓣肠、直肠与肛门。幽门盲囊似一致密器官,小肠与瓣肠连接处有一特殊淋巴器官,肛门两侧有腹孔。白鲟口咽腔被覆层扁平上皮,上皮内有味蕾分布。咽后消化道组织分层为粘膜(无粘膜肌层)、粘膜下层(小肠及瓣肠前部无)、肌层与外膜。粘膜上皮为单层柱状上皮,由纤毛柱状细胞、一般柱状细胞和杯状细胞组成,其间还散在有颗粒细胞和游走细胞。食道后部与胃的一般柱状细胞为分泌粘液的细胞,肠内的一般柱状细胞为吸收细胞。胃后行支及部分前行支固有膜内有消化腺,其余各部的固有膜为致密层。小肠前中部粘膜形成蜂窝状粘膜窦,无肠腺。除食道前部肌层中有横纹肌外,其余部的肌层均为平滑肌。外膜内结缔组织有的致密有的疏松,外膜表面细胞柱状或立方形或扁平。     

江南桤木(Alnus trabeculosa)的花粉形态与其生态因子

采用光学显微镜、扫描电镜和透射电镜对产自安徽省岳西县鹞落坪国家自然保护区的桦木科江南桤木的花粉形态进行了观察和研究。结果表明花粉粒圆球形至近球形,花粉大小为22.5—35.0μm,平均为31.5μm。赤道面观近扁球形,极面观为四角形或五角形。光学显微镜下,4-5孔,孔的结构特殊,内、外层到孔边分离,形成显著的孔室。在光切面看,外层在孔处加厚,孔间带状加厚。同时,在扫描电镜下,萌发孔沿赤道排列,为短萌发孔,萌发孔长轴3.2μm,短轴为1.5μm,其长轴约为短轴的2倍。外壁厚为2.0μm,外壁外层明显厚于内层。外壁纹饰在光学显微镜为不明显的颗粒排列为细条纹,扫描电镜下为微刺。在透射电镜下,花粉壁分为明显的四层,即:覆盖层、柱状层、基层和内层;覆盖层有刺状纹饰等。同时研究了江南桤木花粉的地理分布及其与生态因子的关系。根据江南桤木植物赖以生存的生态因子,得出江南桤木花粉分布区的主要生态因子,包括地理位置、海拔高度、年降水量、年积温及生境,为利用地层中桦木科化石花粉重建古气候、古环境及气候变迁提供了现代孢粉学资料和依据,也为该植物的现代地理分布提供了科学依据。     

江南桤木（Alnus trabeculosa）花粉形态与其生态因子

采用光学显微镜、扫描电镜和透射电镜对产自安徽省岳西县鹞落坪国家自然保护区的桦木科江南桤木的花粉形态进行了观察和研究。结果表明花粉粒圆球形至近球形,花粉大小为22．535．0μm,平均为31．5μm。赤道面观近扁球形,极面观为四角形或五角形。光学显微镜下,4—5孔,孔的结构特殊,内、外层到孔边分离,形成显著的孔室。在光切面看,外层在孔处加厚,孔间带状加厚。同时,在扫描电镜下,萌发孔沿赤道排列,为短萌发孔,萌发孔长轴3．2μm,短轴为1．5μm,其长轴约为短轴的2倍。外壁厚为2．0μm,外壁外层明显厚于内层。外壁纹饰在光学显微镜为不明显的颗粒排列为细条纹,扫描电镜下为微刺。在透射电镜下,花粉壁分为明显的四层,即：覆盖层、柱状层、基层和内层;覆盖层有刺状纹饰等。同时研究了江南桤木花粉的地理分布及其与生态因子的关系。根据江南桤木植物赖以生存的生态因子,得出江南桤木花粉分布区的主要生态因子,包括地理位置、海拔高度、年降水量、年积温及生境,为利用地层中桦木科化石花粉重建古气候、古环境及气候变迁提供了现代孢粉学资料和依据,也为该植物的现代地理分布提供了科学依据。     

椭圆形阿富汗蜓（Afghanella elliptica）──前苏门答腊蜓向苏门答腊蜓演化的中间环节

对伊朗中部阿巴德地区Ｓｕｒｍａｑ组三个层位标本的研究揭示,Ｓｕｍａｔｒｉｎａ旋壁致密层之下缺失蜂巢层,并源于一类壳体纺锤形、蜂巢层极簿的Ａｆｇｈａｎｅｌｌａ;从Ｐｒａｅｓｕｍａｔｒｉｎａ→Ａｆｇｈａｎｅｌｌａｓｃｈｅｎｃｋｉ和由Ｐｒａｅｓｕｍａｔｒｉｎａ→Ａｆｇｈａｎｅｌｌａｅｌｌｉｐｔｉｃａ→Ｓｕｍａｔｒｉｎａ代表了两条独立的演化线系。     

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.