蓝光光照对蛹虫草子实体生长和主要活性成分的影响

光作为一种重要的环境因子,可影响真菌的生长发育、生理周期、形态变化及次级代谢产物的产生,对于蛹虫草而言,光照还是其子实体生长发育的必要条件。选择2株不同来源的蛹虫草菌株,研究了自然光照和蓝光光照条件下,其子实体生长、抗氧化酶活性和主要活性成分的变化。结果表明蓝光光照对于蛹虫草子实体产量没有明显的促进和抑制作用。自然光照条件下成熟子实体的超氧化物歧化酶(superoxide dismutase,SOD)活性显著高于蓝光光照,过氧化氢酶(catalase,CAT)活性没有明显差别,而过氧化物酶(peroxidase,POD)活性则表现出菌株差异。子实体主要活性成分方面,腺苷、甘露醇含量不受蓝光影响,类胡萝卜素在蓝光光照条件下含量极显著高于自然光光照,蓝光对子实体、虫草素、粗多糖含量的影响则存在菌株差异。研究为蛹虫草子实体的栽培条件优化,提高蛹虫草子实体质量提供依据。     

蔗根土天牛高致病力绿僵菌菌株的生物学特性研究

【目的】明确对蔗根土天牛Dorysthenes granulosus具有良好杀虫活性的金龟子绿僵菌Metarhizium anisopliae JC002菌株生长和产孢所需要的最适营养条件和环境条件。【方法】通过单因素试验,测试了不同培养基、碳源、氮源、温度、pH及紫外线照射不同时间对JC002菌株生长和产孢的影响。【结果】JC002菌株培养基的最佳配方是葡萄糖30 g、蛋白胨15 g、马铃薯200 g、琼脂20 g、水1 000 mL;蔗糖、NaNO3是菌落生长及产孢的最适碳源和氮源;菌株培养的最适温度为25℃,培养基的最适pH值为7.0;紫外光对菌株的生长速率无显著影响,但对产孢量有较大的抑制作用,紫外光照射时间越长,产孢越少。【结论】本研究为JC002菌株的大量培养及其孢子制剂的大量生产和有效利用奠定基础。     

蛹虫草的光形态建成及蓝光受体基因Cmwc-1

蛹虫草[Cordyceps militaris(L.)Link],隶属于肉座菌目(Hypocreales),麦角菌科(Clavicipitaceae),虫草属(Cordyceps),其滋补作用和药用功效与名贵但难以人工培养的冬虫夏草相近,并日渐成为冬虫夏草的理想替代品。蛹虫草为虫草属模式种,分布广泛,在人工培养基或昆虫蛹体上能产生无性和有性阶段,其基因组已公布,成为大型真菌生物学研究的理想模型。对真菌而言,光可影响其生长发育、生理周期、形态变化及次级代谢产物产生,光照是蛹虫草子实体生长发育的必要条件,并能够调控其类胡萝卜素的产生。该研究采用5株代表性的蛹虫草菌株,包括1株退化菌株、1株白化菌株和3株在栽培中广泛运用但子实体形态各异的菌株作为对象,研究其光形态建成、克隆蓝光受体基因Cmwc-1并测定在不同光照条件下其表达量的变化。结果表明,除白化菌株外,光照刺激促进菌丝色素的形成,且蓝光的作用优于白光。光照抑制生长速度,所有的菌株在黑暗条件下生长最快,白光次之,蓝光最慢,退化菌株的生长速度在3种培养条件下均优于其他菌株。此外,光照促进分生孢子的产生。退化菌株在白光和蓝光条件下产孢量均最大。为了从分子层面阐明蛹虫草对光刺激的应答反应,该研究通过Hai-l tail PCR和基因步移的方法克隆得到了蓝光受体基因Cmwc-1。CmWC-1是1个GA-TA-Zinc finger型转录因子,含有谷氨酸富集结构域,LOV(Light,Oxygen,or Voltage),PAS(Per-Arn-t Sim)和锌指结构域,与粗糙脉孢霉的蓝光受体结构域组成基本一致。对5个研究对象的CmWC-1序列比较分析发现3个菌株在谷氨酰胺富集结构域缺失5个谷氨酰胺。基于JTT模型的贝叶斯树和最大似然法构建的WC-1系统树,其树形和ITS序列构建的系统树基本一致,且粪壳菌纲的一些主要类群以较高的支持率被划分为单系,说明WC-1可以作为系统进化分析的一个参照。Cmwc-1在黑暗条件下表达,光照刺激后表达量增加,待光照时间持续30 min,其表达量将不再上升,即光适应现象。蛹虫草光受体基因的研究将为子实体发育研究奠定基础。     

蛹虫草对锌的耐性与富集特征

在培养基内添加不同量的锌,研究其对蛹虫草子实体的形成、子实体和菌丝体生物量、子实体多糖含量和葡萄糖含量的影响,以及蛹虫草子实体和菌丝体对锌的富集能力。结果表明锌对上述各项都有影响。液体培养条件下,锌浓度在453906mg/L范围内可以促进菌丝体生长,锌浓度超过4077mg/L时,菌丝生长受到抑制。培养基锌的浓度在4077mg/L以下时,蛹虫草菌丝体锌的富集量随着液体培养基锌浓度的提高而提高。固体培养条件下,锌含量在226453mg/kg范围内可以促进蛹虫草子实体生长,并且在此含量范围内,蛹虫草子实体中葡萄糖含量较高。培养基锌含量在680906mg/kg时,子实体多糖含量较高。培养基锌含量在2038mg/kg以下时,蛹虫草子实体中锌的富集量随着培养基锌含量的提高而提高,在培养基锌含量为2038mg/kg时,子实体中锌的含量达到28570mg/kg(干重)。     

蓝光诱导蛹虫草菌丝类胡萝卜素的积累

蛹虫草(Cordyceps militaris L.)在培养时受蓝光诱导,其菌丝体中有高产量的类胡萝卜素积累.当温度为25℃且蓝光光照强度为6.5μmol·m-2·S-1时,菌丝体的类胡萝卜素含量在含蚕蛹粉的培养基上24h达到最高峰的495.5μg/g FW;而在不含蚕蛹粉的培养基上72h才达最高峰414.1μg/g FW.蛹虫草菌丝类胡萝卜素的积累也受蓝光光照强度的影响,最适光照强度可随培养时间的不同而有所变化.此外,黑暗培养时间的长短和温度也可共同影响蛹虫草菌丝产类胡萝卜素时对蓝光的敏感性.     

蛹虫草菌丝产虫草素液体培养条件的研究

通过对蛹虫草菌丝产虫草素液体培养条件的研究,明确蛹虫草菌丝产虫草素的适宜碳源及浓度,适宜氮源及浓度,最适pH值,最适培养温度,最适转速以及最适培养时间,以便应用于虫草素的工厂化生产。结果表明,蛹虫草菌丝产虫草素的条件：适宜碳源为D-果糖,最适浓度为10g/L;适宜氮源为蛋白胨,最适浓度为15g/L;最适初始pH为7,最适培养温度为24℃,最适转速为180r/min,最适培养时间为9d,其培养液虫草素含量可达到0.537g/L。     

蛹虫草蓝光诱导两步法发酵产类胡萝卜素

采用黑暗摇瓶发酵和蓝光照射静置培养的两步培养法,进行蛹虫草(Cordyceps militaris L.)液体发酵产类胡萝卜素的蓝光诱导。结果表明蛹虫草在2d的黑暗培养和5d的蓝光照射静置培养后,其类胡萝卜素的含量可达到最高值558.4μg/gFW。而以黑暗摇瓶培养2d后,进行不同时间的蓝光照射静置培养。结果表明,蓝光照射最初2d,蛹虫草类胡萝卜素含量变化不明显,随后快速增加,并在第5天达到最大值558.4μg/gFW,随后类胡萝卜素的含量并无明显变化。通过研究解决了蛹虫草液体发酵产类胡萝卜素的培养过程中蓝光的给光问题。     

内生解淀粉芽孢杆菌CC09产Iturin A摇瓶发酵条件优化

【目的】提高内生解淀粉芽孢杆菌CC09发酵产抗菌脂肽Iturin A的产量。【方法】首先采用单因子实验研究了碳源、氮源、NaCl浓度、pH、温度、转速和装液量等因子对CC09产Iturin A能力的影响,然后对其中显著性因子:氮源浓度、pH、温度及装液量4个因素进行正交实验,进一步优化发酵条件。【结果】优化培养基组成及发酵条件可以提高CC09菌株的生长速度及产Iturin A的量,其中可溶性淀粉以及一定比例的蛋白胨和酵母粉是CC09菌株产Iturin A的良好碳源和氮源;培养温度、装液量、培养液pH等也对CC09菌株产Iturin A有显著影响。优化后的培养基成分:可溶性淀粉(碳源)5 g/L、比例为3:1的胰蛋白胨酵母粉混合氮源15 g/L、NaCl 1 g/L;最佳培养条件:pH 6.0、28°C、摇床转速120 r/min、培养瓶装液量20%。【结论】在此条件下,Iturin A的产量可达到690 mg/L,较优化前的138 mg/L提高了4倍。     

一株产碱性蛋白酶菌株的筛选鉴定及酶学特性研究

【目的】从丝茅草中筛选得到产蛋白酶菌株并研究驯化过程中微生物群落结构,以及探究该菌株的生长特性和蛋白酶的酶学特性。【方法】通过高通量测序探究来源于丝茅草的菌株在不同培养条件下细菌种类及丰度,通过选择性培养基来筛选能够分解酪素并产生蛋白酶的菌株,通过单因素试验方法确定环境因子对菌株生长和蛋白酶活性的影响。【结果】微生物群落结构在基础培养基和牛肉膏蛋白胨培养基中不同。通过含酪素的选择性培养基里筛选到1株产蛋白酶菌株H-16,经生理生化试验和16S r DNA鉴定知该菌株属于Escherichia marmotae,菌株H-16能产生分子量为70 k Da左右的单亚基蛋白酶。胰蛋白胨、蔗糖、30°C或35°C、p H 7分别为菌株生长的最适氮源、碳源、温度和p H。菌株H-16分泌的蛋白酶最适p H为6–8,在50°C及6%盐度以下酶活性几乎不受影响。此外,Cu(II)和Ag(I)等金属离子能够抑制蛋白酶的活性。【结论】该菌株H-16为嗜中温菌株,能够产生碱性蛋白酶。     

蛹虫草表型多态性对子实体产生及虫草菌素的影响

为选育高产子实体和虫草菌素的蛹虫草菌株,从野生蛹虫草中分离单孢子并进行分型,之后进行产子实体实验;同时对蛹虫草子实体进行了产孢结构的观察,并用高效液相色谱仪检测了子实体和培养基中的虫草菌素。结果表明,菌落背面颜色为橙铬色的菌株容易产生子实体;出发(原代)菌株所产子实体在形态上更接近野生蛹虫草,而角变株的子实体畸形;出发菌株产子实体能力要比该菌株未发生角变部分分离株和角变部分分离株都强。在虫草菌素的产量上也以出发菌株为高,表明表型多态性对蛹虫草产子实体和虫草菌素有很大的影响。这对于优势菌种的筛选和生产实践有借鉴意义。     

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.