鸡舍环境中tri5基因阳性镰孢菌的分离及其产毒特性

【目的】探讨利用tri5-PCR鉴定产毒镰孢菌的可行性以及tri5阳性菌株的产毒特性和产毒条件。评估鸡舍空气和固体基质中镰孢菌分离株中产单端孢霉烯族毒素潜力的发生率。【方法】利用编码单端孢霉烯族毒素合成酶的起始基因(tri5基因)对139株镰孢菌分离株进行PCR检测,并对tri5阳性菌株进行产毒培养,通过免疫亲和柱-高效液相色谱方法来检测培养产物中的T-2毒素和HT-2毒素含量。【结果】共筛选到42株tri5阳性菌株,其中分离自鸡舍空气中的10株tri5阳性菌株经产毒培养后7株菌株产生T-2毒素(1.36-5 ng/mL)或HT-2毒素(6.1-17.1 ng/mL)。在5℃-20℃间隔24 h变温、光照与黑暗间隔24 h交替、前期振荡后期静止的培养条件下培养9 d镰孢菌的产毒量最高;镰孢菌的产毒量与温度和时间显著相关,而与菌丝体干重无显著相关性。【结论】与传统鉴定产毒镰孢菌的方法比较,tri5-PCR更适用于快速、准确地检测大量鸡舍环境样本中的产毒镰孢菌。本研究为养殖环境的产毒镰孢菌的危害预警和控制提供技术支撑和理论依据。     

一株产T-2毒素镰孢菌的分离、鉴定及其产毒条件的研究

【目的】从青海大骨节病区小麦麦穗中分离的内生真菌中筛选产T-2毒素的菌株,并研究影响其合成该毒素的条件。【方法】采用种子胚芽抑制试验和抑菌试验从分离所得的菌株中筛选产毒菌株;利用薄层层析和高效液相检测待测菌株产物,复筛出产T-2毒素的菌株。通过显微形态学观察及ITS序列分析对筛选出的菌株5-5m-1进行鉴定。应用单因素筛选方案研究固体培养时间、温度以及液体培养转速、初始p H等对其产T-2毒素的影响,并采用正交试验进一步优化。【结果】菌株5-5m-1的显微形态与梨孢镰孢菌(Fusarium poae)相似;ITS序列分析显示,该菌株与F.poae的相似度也较高。其产T-2毒素的最佳条件为:玉米固体培养基、日温25°C/夜温15°C、光暗交替。【结论】5-5m-1菌株为梨孢镰孢菌,培养条件对其产T-2毒素能力有很大影响。实验结果将为进一步研究T-2毒素产生的机制和防止真菌毒素污染提供参考。     

封闭环境气载镰孢菌及其T-2毒素发生规律的研究进展

本文阐述了普遍存在的镰孢菌可增强封闭式环境中群体对疾病的易感性,并通过其次生代谢产物(如T-2毒素)对人和动物造成严重危害及预防和控制气载镰孢菌及T-2毒素危害的相关问题,包括气载真菌和毒素采集、毒素痕量富集技术、不同环境中的镰孢菌变化规律与产毒基因研究现状。提出研究封闭式环境中气载镰孢菌及T-2毒素发生规律研究的必要性。     

鸡舍环境中镰孢菌的种类分布及潜在产单端孢霉烯族毒素菌株的检测

采用AGI-30生物采样器收集鸡舍空气样本,同时采集鸡舍中饲料、积尘、土壤和饮用水在内的环境基质样品。采用形态学方法对分离获得的镰孢菌菌株进行鉴定,利用tri5-PCR技术对镰孢菌菌株中产单端孢霉烯族毒素的菌株进行检测,目的是探明鸡舍环境中镰孢菌种类的分布特征和产毒菌株。结果表明,从采集的50份样品中分离获得139个镰孢菌菌株,鸡舍空气和基质中的优势菌株均为Fusarium verticillioides;在各基质中,土壤中镰孢菌总浓度最高,为4×102–1.35×104CFU/g,其次为饲料和饮用水;采用tri5-PCR技术筛选到42株tri5阳性镰孢菌菌株,其中以F. graminearum所占比例最高。研究明确鸡舍中镰孢菌种类及其分布特征对鸡只疾病控制及保障人类和动物的健康具有重要意义。     

利用Fusarium poae制备T-2毒素的培养条件和提取方法

比较2种不同优化方法对分离纯化梨孢镰孢菌(Fusarium poae)产生的T-2毒素的效果,并得到高纯度的T-2毒素,解决国内T-2毒素产业化问题.在优化Fusarium poae产毒培养条件的基础上,对Burmeister的提取方法和Gregory培养基进一步优化以最大限度地提高T-2毒素的产率,从而得到高纯度并且...     

对虾肠道中T-2毒素降解菌的分离纯化与鉴定

从新鲜健康的凡纳滨对虾肠道中分离筛选和鉴定降解T-2毒素微生物,为日后进一步研究T-2毒素(T-2)降解菌株的相关特性及其分布规律提供参考。取新鲜健康的凡纳滨对虾肠道,通过对该肠道菌群进行定性定量分析;从T-2与对虾肠道共培养液分离纯化得到6株优势菌株;将6株优势菌株分别和T-2在胰蛋白胨大豆(TSB)肉汤中进行共培养,采用LC-MS/MS法检测该培养液前后T-2含量,筛选得到T-2降解菌株,并用微生物鉴定仪VITEK2和16S rRNA鉴定目标菌株。TSB肉汤中检测T-2的标准曲线线性良好(R=0.999 5),T-2加标回收率为91.5%~108.4%,检测限为0.01 ng/m L,相对标准偏差为0.0%~8.4%和精密度为94.5%~107%。对虾肠道中的蜡状芽胞杆菌(Bacillus cereus)和阴沟肠杆菌(Enterobacter cloacae)对T-2毒素降解率最高,分别达到91.8%和78.8%。     

红外-核磁共振光谱-免疫亲和柱法解析梨孢镰孢菌代谢产物成分

利用红外光谱,核磁共振光谱结合免疫亲和柱的方法解析梨孢镰孢菌代谢产物成分,为真菌代谢产物的分析提供新的信息.将F.Poae菌株在GYM培养基上25℃条件下培养12 h后转至8℃培养12h,交替进行4周,将其代谢产物分离纯化、结晶,80℃干燥后用红外光谱议分析产物结构,然后利用免疫亲和柱特异性,比较产物经T-2免疫亲和柱纯化前后的1H核磁谱图.由红外谱图可判断目标组分存在与单端孢霉烯族毒素相同的特征官能团,初步判定产物为单端孢霉烯族毒素.通过1H核磁谱图比较T-2免疫亲和柱纯化前后物质结构一致.梨孢镰孢菌代谢产物成分为T-2毒素.红外-核磁共振光谱结合免疫亲和柱的方法解析梨孢镰孢菌代谢产物的方法在国内外尚未见报道.     

氯氰菊酯降解菌株L12的分离鉴定及降解特性

[目的]通过分离纯化氯氰菊酯降解菌,研究降解特性为实际应用提供理论依据.[方法]利用富集驯化培养技术分离菌株,通过形态、生理生化特征及16S rRNA基因序列分析鉴定菌株.测定培养液中氯氰菊酯的浓度和代谢产物以及菌体细胞的密度和细胞表面疏水性,研究菌株的降解特性.[结果]从生产氯氰菊酯的农药厂污水曝气池中,分离到1株能...     

蛇足石杉中产石杉碱甲内生真菌的分离和鉴定

【目的】从野生蛇足石杉(Huperzia serrata)中分离筛选产石杉碱甲的内生真菌。【方法】采用薄层层析及高效液相色谱法对内生真菌代谢产物进行测定和分析以期分离获得产石杉碱甲菌株,运用形态及ITS序列分析方法对产石杉碱甲菌株进行鉴定,并利用连续传代方法考察菌株遗传稳定性。【结果】经筛选获得一株产石杉碱甲内生真菌NSH-5,经形态学鉴定及ITS序列分析鉴定为轮枝镰孢菌(Fusarium verticillioides),其石杉碱甲产量为11.76 mg/100 m L,菌株经20次连续传代后遗传稳定。【结论】NSH-5菌株为一株具有产石杉碱甲能力的轮枝镰孢菌,该菌株的发现为生物合成石杉碱甲提供了新的菌种资源。     

一株高效拮抗向日葵菌核菌的细菌菌株YC16的筛选及其作用效果研究

[目的]筛选高效拮抗向日葵菌核菌的细菌菌株,为开发防治菌核菌病害、提高向日葵产量的生物菌剂提供菌种资源。[方法]以羧甲基纤维素钠(CMC)、小麦秸秆纤维素为唯一碳源的无机盐培养基,分离高效降解纤维素的细菌菌株;采用纤维素降解菌与菌核菌的平板对峙方法,进一步筛选拮抗菌核菌的菌株;利用16S rDNA序列鉴定菌株、PDYA平板对峙实验检验上述所选拮抗菌株的抑菌谱;采用离体向日葵新鲜叶片、草炭土基质盆栽实验,观察拮抗菌菌株抑制菌核菌生长的能力;温室盆栽和田间试验条件下,研究其防治向日葵菌核菌病害、促进生长和提高产量的效果。[结果]筛选了一株高效抑制菌核菌的细菌YC16,经过16S rDNA序列分析,鉴定为解淀粉芽孢杆菌。YC16菌株能够抑制8种病原真菌生长,包括齐整小核菌、腐皮镰孢菌、尖孢镰刀菌、稻梨孢、辣椒疫霉、镰刀菌、尖镰孢黄瓜专化型和向日葵菌核菌;抑制菌核菌感染叶片,抑制率达到了80.42%;抑制盆栽基质中菌核菌的菌丝生长,基质表面菌丝密度比对照减少了50%以上。盆栽接种YC16的向日葵生物量比对照提高54.9%,田间向日葵接种YC16菌剂对菌核菌引发的盘腐病防治效果达39%-100%,产量提高24.4%-30.2%。[结论]YC16生物菌剂施用于土壤,能够有效防治向日葵的茎腐病和盘腐病,展现了防治向日葵菌核病和提高产量的双重效果,是一株具有良好应用前景的高效菌种资源。     

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.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.