海绵硅蛋白研究进展

海绵是生物进化过程中最古老的多细胞动物,其中大部分能够利用二氧化硅在常温水环境下合成形状、大小和结构极为丰富的硅质骨骼。随着近年来人们发现其骨骼的基本组成单位骨针具有优异的光导性能和机械性能,海绵生物硅化过程及仿生纳米和微米硅质生物材料合成的研究成为生物技术和材料科学的热点。在海绵生物硅化过程中,一类被称为硅蛋白(Silicatein)的蛋白质表现出了特殊的催化活性,也因此得到了生物学家、化学家和材料学家的关注。以下将对硅蛋白的国际研究现状进行了评述,以期促进国内相关领域的研究。     

深海六放海绵大骨针的结构与特性

在海绵动物(多孔动物)中,六放海绵和寻常海绵为硅质骨骼.生活在深海(1 000 m)中的六放海绵是最古老的海绵动物,其中间单根海绵和春氏单根海绵有长达3 m的骨针,是地球上最长的生物硅结构.利用电子显微技术观测, 这些直径达8 mm的巨大根须骨针具有同心层状结构,其横截面显示明显的构造分界:中间为含有轴丝的轴管,外围是一50-150 μm厚的轴筒,最外面为区状区(300-500层,每层厚度3-5 μm).生物化学研究显示其主要的蛋白质为35 kD大分子,另外,还检测到23-24 kD 多肽,可能是硅蛋白相关蛋白.依据现有的红血球凝聚活性,从骨针提取物中也检测到了凝集素.由电子探针获得其化学成分主要为Si,K和Na.此外,骨针的光传输实验表明,该巨大根须骨针用作光纤可传输600 nm至1 400 nm范围的光,而滤掉小于600 nm的光(类似高通滤波器)和大于1 400 nm 的红外光(类似低通滤波器).另外,从六放海绵的空囊泡沫海绵中分离出一个基因并确证了其推导的编码蛋白序列,该蛋白编码一个光裂合酶相关蛋白,蛋白相似性比较结果显示属于光裂合酶相关蛋白中多细胞动物隐色素一类.基于以上数据给出了六放海绵硅质骨针形成的示意图.另外,由单根海绵骨针可作为波导传输光/电和/或化学信号,推断在海绵动物中有类似神经系统的网络系统[动物学报 53(3):557-569,2007].     

陕西镇巴早寒武世海绵骨针化石

作者对采自陕西省镇巴县下寒武统西蒿坪段和水井沱组下部碳酸盐岩地层的海绵骨针化石进行了研究。三叶虫及小壳化石的生物地层学资料表明西蒿坪段和水井沱组下段属于筇竹寺阶。化石经室内醋酸浸泡处理后获得,骨针化石保存较好、类型多样,其中属于六射海绵纲的骨针3类,普通海绵纲的骨针6类,分类未定的骨针1类(Nabaviellasp.);并详细地对各类骨针化石进行了描述。虽然普通海绵骨针类型多样,但六射海绵的骨针丰度远高于普通海绵。简要地探讨了海绵骨针的保存方式,对比和分析了西蒿坪段和水井沱组海绵骨针化石组成的差异。结合同时代产自皖南荷塘组和云南澄江动物群中特异保存的海绵软躯体化石资料,认为虽然海绵动物起源于新元古代末期,但躯体海绵化石和骨针化石都显示海绵动物的大辐射事件发生在早寒武世筇竹寺期。     

吉林大阳岔寒武系-奥陶系界线剖面冶里组海绿石化海绵骨针化石

大阳岔寒武系-奥陶系界线剖面的界线附近地层（冶里组下部）中富含海绵骨针化石,其中部分骨针化石以次生海绿石化方式保存。海绵骨针的海绿石化与骨针的原始成分蛋白石有关,蛋白石不稳定,常脱水后在成岩过程中转变为石英;在寒武纪-奥陶纪过渡时期,此地的沉积速率较小,沉积了一套海绿石凝缩层,在局部弱碱性环境中,蛋白石质的海绵骨针易于溶解,且被海绿石所替代,蛋白石的溶解与海绿石的晶出替代近为同步,致使骨针形态完好保存。海绿石化海绵骨针共有4种类型：单轴骨针,四射二轴骨针（或十字骨针）,五射三轴骨针及六射三轴骨针;其中四射二轴骨针丰度相对较高。单轴骨针可能为普通海绵纲的骨针,其余骨针都为六射海绵纲的特征骨针。     

海绵的分类、演化及其地质意义

本文简述了海绵动物的基本特征,比较了硅质海绵与钙质海绵在骨针及骨骼结构上的不同,认为骨针性质与硬体骨骼结构是海绵分类的主要依据。据此把海绵动物划分为普通海绵纲(Class Demospongea)、六射海绵纲(Class Hexactinellida)、钙质海绵纲(Class Calcispongiae)、异射海绵纲(Class Heteractinida)和硬骨海绵纲(Class Sclerospongiae),并进一步讨论了不同类别海绵在地史时期的分布及演化。提出海绵除可作为判别环境的标志外,还是重要的造礁生物。地史时期由海绵形成的成礁期有3次,它们与不同类型碳酸盐岩隆的生成及油气的聚集有密切关系。     

中国海表层沉积生物硅含量与硅藻丰度空间分布规律

生物硅是海洋硅循环及古海洋学的主要研究对象,主要由硅藻、放射虫、硅鞭藻和海绵骨针等硅质生物壳体组成.由于硅藻是海洋硅质生物以及海洋浮游植物群落的优势种群,故生物硅常被用作判断硅藻生产力甚至整个海洋初级生产力的重要指标.相对于硅藻的鉴定和统计分析,生物硅含量分析有其便利快捷的明显优势,然而生物硅组成的复杂性使其在现代海洋...     

贵州寒武系九门冲组和渣拉沟组中的海绵骨针化石

贵州寒武系九门冲组和渣拉沟组中的海绵骨针化石经室内醋酸浸泡处理后获得,主要由有次级分枝的单轴针、具刺二轴四射针、三轴五射针、斜五射三轴针和三轴六射针组成,分属普通海绵和六射海绵类。其分异度明显低于陕西省镇坪县筇竹寺组、镇巴县灯影组西蒿坪段和水井沱组的海绵骨针组合,特别是镇巴地区灯影组西蒿坪段和水井沱组的普通海绵纲骨针化石类型如正多射骨针(orthopolyactines)、正顶多叉杆式骨针(orthopolyaenes)及顶三叉杆式骨针(triaenes)等类型在贵州深水区的九门冲组和渣拉沟组中均未发现。这些差异可能是由于当时贵州丹寨、三都地区的水体较深导致。     

贵州下寒武统牛蹄塘生物群中海绵新材料

描述了贵州下寒武统牛蹄塘生物群中海绵化石1新属(Zunyispongiagen.nov.),2新种(Zunyispongiatriangulariagen.etsp.nov.,Choiafanensis.sp.nov.),通过对其形态功能的分析和讨论证实了寒武纪早期海绵动物的骨骼是由细小骨针向粗大骨针演变,骨架结构从不稳定型向稳定型发展。     

云南澄江下寒武统细丝海绵化石

前言澄江海绵化石群的系统分类学、生态学、埋藏学和演化生物学等问题将分为不同专题进行研究。本文是关于澄江海绵化石的第一篇报道,研究内容侧重于细丝海绵科系统分类学。细丝海绵科属于普通海绵类,为澄江海绵群体中的优势类型,也是最为原始的普通海绵类之一。它们的骨骼甚薄,主要由席状外骨层所组成。外骨层由大小不相同的两套单轴骨针纵向排列而成;大骨针互相叠接成骨棒状或互相交错排列成网状,以便起着主要的支撑作用。大骨针之     

网角海绵目(Dictyoceratida)谱系发育与形态发生分析

采用形态和分子数据相结合的方法探讨网角海绵目谱系发育和骨骼形态发生问题。根据11个普通海绵种的18S rRNA序列,结合11个形态与结构特征以及生化和细胞学性状,对网角海绵目的系统发育关系进行综合分析。分子系统学分析表明,网角海绵目及角骨海绵科为单系类群,具有宽口型领细胞室的掘海绵科属于网角海绵目。表型数据显示,网角海绵目内的4个科(Dysideidae,Thorectidae,Irciniidae,Spongiidae)为单系类群。网角海绵目的单系性表明具有等级分化特征的海绵质骨架纤维为同源特征,而领细胞室类型的分化,即宽口型和二咽型领细胞室的分化,是在网角海绵内部类群分化的同时发生的。结合角海绵类及相关类群的化石记录和文中关于网角海绵谱系发育分析推测,早期网角海绵可能主要通过胶原纤维粘附外源碎屑颗粒来支撑内部骨架系统;网角海绵的演化向两个方向发展:①合成多种海绵质纤维取代外源物形成骨架系统(网角海绵和指角海绵);②合成硅质骨针取代外源颗粒构成海绵骨架(现代所有具有骨针的普通海绵)。     

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.