甘草药材上的污染真菌类群及其产毒素特性

对药材市场上霉变甘草样品的污染真菌进行分析,共得到4属7种真菌,包括Penicillium、Aspergillus、Fusarium、Mucor属,其中Penicillium polonicum、Aspergillus parasiticus以及P.crustosum是优势真菌。采用高效液相色谱-质谱联用技术对优势菌菌株产黄曲霉毒素及赭曲霉毒素A的特性进行检测。结果表明A.parasiticus主要产生黄曲霉毒素(AFG2、AFG1、AFB2、AFB1)和赭曲霉毒素A(OTA);而Penicillium polonicum主要产生赭曲霉毒素A(OTA)。     

一株产赭曲霉毒素A黑曲霉及其产毒条件

以甘肃河西走廊葡萄酒产区分离的曲霉属黑色组H1菌株为试验材料,依据形态特征和基于rDNA ITS、β-tubulin及calmodulin基因序列的系统发育分析,将其鉴定为黑曲霉Aspergillus niger。利用HPLC-FLD和UPLC-MS/MS检测分析确认H1菌株具有产生赭曲霉毒素A(OTA)的能力。进一步研究了培养条件对H1菌株产毒的影响。试验结果表明,YES培养基比CYA培养基更利于H1菌株的营养生长和产OTA;18–25℃,该菌生长较慢,但OTA产量高;18℃H1菌株在YES培养基上培养9d时OTA的产量达到最大值,为26.01μg/g YES;30–37℃该菌的生长速率显著提高,但OTA产量很低,甚至不产OTA。试验结果表明,温度和营养条件是影响H1菌株产生OTA能力的重要因素。     

产赭曲霉毒素A黑曲霉的PCR法检测

【目的】快速检测产赭曲霉毒素A(OTA)的黑曲霉。【方法】根据黑曲霉(Aspergillus niger)CBS513.88中An15g07920基因编码聚酮合酶的酰基转移酶(AT)域设计引物,建立针对产OTA黑曲霉的聚合酶链式反应(PCR)检测方法。【结果】对72株曲霉属菌株(黑曲霉、炭黑曲霉、赭曲霉、佩特曲霉、寄生曲霉和塔宾曲霉)进行检测,发现产OTA的黑曲霉能够扩增出特异性条带,而产OTA的其它菌株不能扩增出条带;检测出3株假阳性的产OTA黑曲霉,实时定量PCR分析此3株菌中An15g07920的同源基因表达情况,发现在产毒条件下可正常表达,排除了因基因无法表达导致假阳性的可能。本方法的检测灵敏度为25 pg的DNA含量,在污染所试农产品孢子浓度大于4.0×10~4–4.0×10~5个/g时可有效检测出产毒菌株。【结论】本方法虽会产生4%的假阳性结果,但是仍可作为产毒黑曲霉有效的快速检测方法,并在农产品污染产毒黑曲霉时进行有效预警。     

赭曲霉毒素A的产生、毒性机制与生物合成研究进展

赭曲霉毒素A(ochratoxin A, OTA)是曲霉属和青霉属等真菌的次生代谢物,广泛污染谷物、葡萄、坚果等农产品和饲料,造成严重的经济损失。此外,OTA的肝肾毒性和三致作用(致畸、致癌、致突变)已经得到越来越多的数据支撑,证实其对人类健康存在巨大威胁。OTA及其衍生物的理化性质已经有较为全面的研究,但是其合成过程及调控机理尚不明确。本文整理了赭曲霉毒素A的理化性质及产毒菌株,总结了OTA污染及致病情况的最新研究进展和各国的限量标准,最后分析了OTA的合成机制,讨论了未来OTA理论及应用层面的研究方向,为赭曲霉毒素A的风险评估提供数据支持,同时为OTA生物合成和调控机制提供理论参考。     

分离自贵州腊肉表面霉菌的三个中国新记录种

从贵州黔南布依族苗族自治州和黔西六盘水市农家自制腊肉表面分离得到的霉菌经形态学和基于钙调蛋白基因(calmodulin gene,Ca M)、RNA多聚酶Ⅱ第二大亚基基因(DNA-dependent RNA polymeraseⅡsecond largest subunit gene,Rpb2)和rDNA ITS1-5.8S-ITS2 (ITS)序列的分析,鉴定出曲霉Aspergillus 8种和青霉Penicillium 1种,即堆积曲霉A. cumulatus、黄曲霉A. flavus、灰绿曲霉A.glaucus、詹森曲霉A. jensenii、多育曲霉A. proliferans、伪灰绿曲霉A. pseudoglaucus、田纳西曲霉A. tennesseensis、产毒曲霉A. venenatus和橘紫青霉P. aurantioviolaceum。其中A. cumulatus、A. venenatus和P.aurantioviolaceum为中国3个新记录种。     

曲霉属黄绿组的一个产毒新种

本文报道曲霉属黄绿组(通常称黄曲霉群)的一个产毒新种肇庆曲霉(Aspergillus zhaoqingensis sp.nov.)。该菌分离广东肇庆土壤,在形态上近于米曲霉(A.oryzae),但作为该组的关键分类特征分生孢子纹饰很不相同:本种的分生孢子明显的粗疏粗糙至具不规则的脊状突起而米曲霉则为光滑或稍粗糙。本种能产生黄曲霉毒素B_1而米曲霉则不产生。本菌亦不同于组内其它菌种。文中对与黄曲霉密切相关诸种也作了简短的讨论。     

不同发酵茶中优势真菌的分离鉴定 及产消化酶活性比较

目的分离鉴定云南普洱茶、广州小青柑、广西六堡茶和湖南熙茯茶中的主要真菌,并探讨其产消化酶活性。方法采用平板涂布法分离不同发酵茶中的真菌,通过其ITS序列进行分子鉴定;利用平板透明圈法测定不同真菌的产淀粉酶、蛋白酶、纤维素酶和脂肪酶活性。结果从4种发酵茶中共分离出8种真菌,其中,在云南普洱茶中分离出2种真菌,分别为篮状菌(Talaromyces. sp.)和T.variabilis;广州小青柑中分离出3种真菌,分别为阿曲霉(Aspergillus amstelodami)、烟曲霉(A.fumigatus)和绳状篮状菌(T.funiculosus);广西六堡茶中分离出2种真菌,分别为黑曲霉(A.niger)和冠突曲霉(A.cristatus);湖南熙茯茶中仅分离出谢瓦曲霉(A.chevalieri)。其中Talaromyces. sp.、T.variabilis、A.niger、A.amstelodami、A.fumigatus、T.funiculosus有产纤维素酶活性,Talaromyces. sp.、T.variabilis、A.cristatus、A.fumigatus、T.funiculosus有产淀粉酶活性,Talaromyces. sp.、T.variabilis、A.niger、A.fumigatus、T.funiculosus有产蛋白酶活性,A.niger有产脂肪酶活性。在8种真菌中,T.variabilis、烟曲霉和绳状篮状菌可同时产纤维素酶、淀粉酶和蛋白酶;黑曲霉能同时产纤维素酶、蛋白酶和脂肪酶;冠突曲霉仅有产淀粉酶活性;阿曲霉仅有产纤维素酶活性。通过比较不同真菌的产酶活性表明,烟曲霉的产蛋白酶活性能力最强;Talaromyces sp.的产纤维酶活性能力最强;Talaromyces. sp.和绳状篮状菌的产淀粉酶活性最强。结论发酵茶的真菌以曲霉菌属Aspergillus、散囊菌属Eurotium和篮状菌属Talaromyces为主,多数真菌具有产消化酶活性,这些酶可能在茶叶发酵过程中起重要作用,并影响发酵茶叶的品质。     

黑曲霉中生物合成赭曲霉毒素A的非核糖体肽合成酶基因的鉴定

赭曲霉毒素A(ochratoxin A,OTA)是国际癌症研究机构认定的"2B"类致癌物。黑曲霉Aspergillus niger是美国食品药品监督局认可的食品安全菌。然而近年来陆续发现某些黑曲霉菌株能够产生OTA,这会对人类健康构成潜在威胁。阐明黑曲霉生物合成OTA的关键基因有助于理解OTA生物合成机制,这对OTA污染的防控具有重要意义。本研究克隆了产OTA黑曲霉中非核糖体肽合成酶(NRPS)编码基因(An15g07910),并对其进行了生物信息学分析,在此基础上采用同源重组的方法敲除了该基因,获得了一株性能稳定的敲除突变株Δnrps。与野生株相比,Δnrps突变株的表型在CYA培养基中并无明显改变,但在7d培养期间完全失去了合成赭曲霉毒素α(ochratoxinα,OTα)和OTA的能力,而赭曲霉毒素β(ochratoxinβ,OTβ)的合成不受影响。在野生株培养过程中,该nrps基因前4d表达量逐渐增大,并在第4天达到最高,随后基因表达量逐渐下降并趋于稳定,这与OTA的含量变化基本一致。结果表明该nrps基因(An15g07910)参与OTA的生物合成,其编码的NRPS可能负责催化苯丙氨酸部分和二氢异香豆素部分的交联。     

氧脂素对赭曲霉在大豆培养基质中合成赭曲霉毒素A的影响

【背景】赭曲霉毒素A (ochratoxin A,OTA)是曲霉属和青霉属等真菌的次级代谢产物,严重威胁农产品及食品安全,氧脂素羟基十八碳二烯酸(hydroxyoctadecaenoic acids,HODEs)被认为可能是曲霉属的群体感应信号分子,调节曲霉的生长发育和次级代谢物生成。【目的】主要研究HODEs对赭曲霉(Aspergillusochraceus)菌株AS3.4412产生OTA的影响,检测孢子密度、培养基类别以及内、外源HODEs作用下OTA产量的不同变化。【方法】分别在PDB、黄豆和黑豆培养基中进行赭曲霉的培养,采用高效液相色谱-荧光检测法测定OTA含量,采用高效液相色谱-质谱法测定氧脂素含量,根据变化规律寻找赭曲霉群体密度、氧脂素、OTA三者间的关系。【结果】低密度赭曲霉培养物(103 spores/mL)中9(S)-HODE/13(S)-HODE及OTA产量高于高密度赭曲霉(106 spores/mL);外源添加9(S)-HODE能促进OTA合成,13(S)-HODE可以抑制OTA合成;赭曲霉侵染抗氧化能力更高的黑豆产生更多的OTA。【结论】OTA的合成受到赭曲霉群体密度和氧脂素的影响,推测9(S)-HODE和13(S)-HODE是赭曲霉群体感应信号分子,并且二者在调节OTA合成中具有相反的作用。     

一株产赭曲霉毒素A黑曲霉的筛选与鉴定

【目的】筛选出可产生赭曲霉毒素A (OTA)的霉菌菌株。【方法】利用CYA和YES培养基从实验室32个霉菌样品中筛选目的菌株。利用高效液相色谱-荧光检测法对OTA产生菌进行初筛,利用高效液相色谱-质谱联用对OTA初筛菌株进行复筛。通过菌落形态、菌丝及分生孢子形态、ITS DNA序列、β-Tubulin基因序列及Calmodulin基因序列分析等鉴定目的菌株。【结果】得到一株OTA产生菌株1062,该菌株能在25 °C条件下,在CYA、YES和CA培养基中很好生长。结合形态学、对培养基的要求以及上述3个基因序列的进化树分析,该菌株属于黑曲霉(Aspergillus niger)。【结论】菌株1062具有OTA产生能力,是一株黑曲霉。     

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.