小单孢菌属的分类及应用研究*

小单孢菌在自然界分布广泛,但由于分离、分类方法所限,绝大多数还没有被人们所认识。在小单孢菌的分类学研究中,最初主要依据的是形态特征、培养特征及生理生化特征等表观分类学指征,随着“多相分类”的广泛应用,分子分类在小单孢菌的分类学研究中起到了越来越重要的作用。小单孢菌是寻找新的生物活性物质的重要菌源,某些种能产生抗生素,如庆大霉素、利福霉素、新霉素等;某些种能降解天然橡胶和纤维素。近年来的研究表明,小单孢菌能产生具有独特化学结构的生物活性物质,对肿瘤细胞有靶向和识别作用,并能有效地杀死肿瘤细胞。     

糖多孢菌属的多相分类

在糖多孢菌属的分类学研究中,最初是根据形态特征、培养特征及生理生化特征等表观分类学指征进行研究。随着“多相分类”方法的广泛应用,化学分类和分子分类在糖多孢菌属的分类学研究中起到越来越重要的作用。糖多孢菌是寻找新的生物活性物质的重要菌源,某些种能产生重要的生物活性物质,如抗生素、酶类、维生素、藻类促生长因子、纤维素降解促进因子、免疫抑制剂等。     

小单孢菌科放线菌的研究进展

小单孢菌科（Micromonosporaceae）菌株是一类具有气生菌丝和基内菌丝分化的经典放线菌,于二十世纪中期被发现,目前包含29属246种的成员。这类菌株不仅广泛分布于普通的陆地生态系统中,在淡水生态系统、海洋生态系统以及一些被认为对生命极具挑战的极端环境中也常能探测到这些微生物的踪迹。小单孢菌产生的抗生素和其他生物活性物质被广泛应用于医疗和农业的多个领域,一直以来受到研究人员的广泛关注。本文就小单孢菌科放线菌的分类学特征、生态分布、基因组特征及其在医药和农业领域的应用情况进行了综述,以期为推进小单孢菌科放线菌资源的高质量发掘奠定基础。     

小单孢菌及其在海洋药物开发中的前景

小单孢菌是除链霉菌外,生产抗生素的另一大家族。从分类地位、生态分布、分离方法以及产生物活性物质的状况等方面,介绍了小单孢菌研究的历史和现状。展望了小单孢菌在海洋药物开发中的前景。     

1株新抑锈病素产生菌FIM03-1149的分离鉴别

在寻找新型抗真菌抗生素的过程中,从海洋放线菌FIM03-1149发酵液中分离到抗真菌抗生素新抑锈病素(Neorustmicin)。菌株FIM03-1149在多数培养基上生长良好,淡黄-橙黄色,无气生菌丝,不产生可溶性色素。形态特征、化学分类特征和生理生化特性等研究表明菌株FIM03-1149属于小单孢菌属。16SrRNA基因序列分析也表明菌株FIM03-1149属于小单孢菌属,但与最接近已知种Micromonospora siamensisTT2-4T处于不同的进化分支,2个菌株在某些生理生化特性上也有不同。基于上述数据,菌株FIM03-1149可能是小单孢菌属的1个新种。     

小单孢菌属特异寡核苷酸探针的设计及杂交条件优化

小单孢菌在生态环境中占有重要地位,也是寻找新的抗生素的重要来源.为了探索小单孢菌的生态分布和在未培养情况下的生态位,在分离和鉴定一定数量的小单孢菌的情况下利用小单孢菌属的16S rDNA基因同源性,采用ClustalX软件进行序列分析,设计了小单孢菌属的16S rRNA特异寡核苷酸探针Mn1和Mn3两个序列,将这两个序列与GenBank中小单孢和非小单孢菌属的16S rRNA序列进行Blastn比对分析,先在理论上确认Mn1和Mn3对小单孢菌属是特异的.收集小单孢和非小单孢菌株19株,通过原位杂交试验的方法对设计的探针进行特异性验证,结果证明,Mn1能和试验用到的所有小单孢菌属的标准菌株杂交和非小单孢菌均不能杂交;Mn3能和所有小单孢菌属的标准菌株杂交,但也能与链霉菌CGMCC4.891(Streptomyces microflavus)杂交.初步证明Mn1可作为小单孢菌属的特异性探针.并通过杂交条件试验优化了Mn1荧光原位杂交的条件:甲酰胺浓度为30%,溶菌酶处理时间为37℃ 40 min,HCl处理时间为60 min,杂交时间为3 h.     

炭样小单孢菌JXNU-1基因打靶载体的构建

小单孢菌属放线菌是许多生物活性物质的重要来源,但自然条件下小单孢菌的活性产物产率普遍偏低,基因编辑与改造对提高小单孢菌属放线菌活性产物的产率具有重要意义。然而,有效的遗传转化体系成为小单孢菌属放线菌基因编辑改造的瓶颈。炭样小单孢菌JXUN-1是实验室从南昌瑶湖农田土壤样品中分离到的一株具有广谱抗菌活性的放线菌,其基因组具有GC含量高的特点。本研究以敲除炭样小单孢菌JXNU-1中抗生素合成相关基因P450为例,以温敏型质粒pKC1139为模板,构建了炭样小单孢菌JXNU-1 P450基因打靶载体p FD306,然后通过电转化将pFD306导入炭样小单孢菌JXNU-1新鲜菌丝体内,通过双交换获得基因缺失株炭样小单孢菌JXNU-ΔP450,最后通过PCR验证了菌株P450基因的缺失,表明炭样小单孢菌JXNU-1基因打靶载体pFD306构建成功。本研究确证了质粒pKC1139可以用于炭样小单孢菌JXNU-1基因组的编辑,为炭样小单孢菌JXNU-1抗生素合成相关基因的筛选及其功能研究提供有效帮助。     

小单孢菌及其产生抗菌素的研究进展

产生抗菌素的微生物种类繁多,除霉菌、细菌、链霉菌外,小单孢菌近年来也被人们所重视。1905年Foulerton从空气中分离到青铜色小单孢菌(Micromonospora chalcea),1923年φrskov建立了小单孢菌属。但是,小单孢菌的拮抗作用直到1942年才为Welsch发现。     

抗菌素104的研究I．玫瑰绛红小单孢菌(Micromonospora roseopurpurea n．Sp.)的鉴定

从我国江苏洪泽湖土壤中分离到一株产生抗菌素104的小单孢菌。经过形态,培养特征和生理特性等方面的研究,它在合成培养基上产生紫褐色的菌丝体和可溶性色素,分解纤维素能力较强,属于紫色小单孢菌类群,但与国内外资料发表的已知种均不相同,定名为致瑰绛红小单孢菌(Micromonospora roseopurpurea n. sp.)。     

一株来源于海洋的抗肿瘤放线菌的分离鉴定

从福建东海海滩土样品中分离到一株海洋放线菌FIM02-523, 该菌株的发酵产物具有抗肿瘤活性。菌株FIM02-523在多数培养基上生长良好, 橙色-暗棕色, 无气生菌丝, 不产生可溶性色素。系统发育、化学分类特征、形态特征、生理生化特性等分析表明菌株FIM02-523是小单孢菌属(Micromonospora), 可能是模式菌种青铜小单孢菌(Micromonospora chalcea)的一个菌株。     

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.