应用小鼠杂交瘤细胞检测支原体

一般支原体都有胸苷磷酸化酶,此酶可将胸苷（Thd）分解为胸腺嘧啶（Thy）和戊糖-1-磷酸酯。培养于HAT培养液的小鼠杂交瘤细胞,利用Thd合成DNA而生长;当HAT培养液中的Thd被支原体的胸苷磷酸化酶分解为Thy后,杂交瘤细胞因不能利用Thy合成DNA而死亡。可根据HAT培养液中杂交瘤细胞的死亡与否来推断检测样品“有”、“无”产胸苷磷酸化酶的支原体存在。     

链霉菌YIM 245次生代谢产物的研究

利用多种柱色谱层析方法从来自非洲特有动物之一长颈鹿(Giraffa camelopardalisc)的粪便链霉菌YIM245的发酵产物中分离得到7个化合物,通过理化性质及波谱数据分析,分别鉴定为2'-脱氧胞嘧啶核苷(1)、2’-脱氧胸苷(2)、2’-脱氧尿苷(3)、2’-脱氧腺苷(4)、菜油甾醇(5)、大豆素(6)和邻氨基苯甲酸(7)。应用96孔板法测定了化合物对5种病原指示菌的最低抑制浓度(MIC),结果表明该7个化合物均显示较弱的抗菌活性。     

整细胞酶促合成抗HIV新药 D-D4FC

D-D4FC(β-D-2′,3′-双脱氢双脱氧-5-氟胞嘧啶核苷)是一种新型抗HIV病毒的核苷类药物,目前正在美国、法国和德国进行Ⅱ期临床。利用乳酸杆菌提取的粗制N-脱氧核糖转移酶实现了由D4T(β-D-2′,3′-双脱氢双脱氧-胸苷,司他夫定)和5-FC(5-氟胞嘧啶)合成D-D4FC,转化率达到25%。现在,发现利用乳酸杆菌整细胞也可实现此反应,其转化率经过12.5h可达到50%,更有利于可能的工业化连续生产。研究了整细胞催化合成D-D4FC反应中,pH值、缓冲液类型、底物浓度、加菌量、反应时间等条件的影响并进行了优化,探讨了反应中乳酸杆菌整细胞催化的可能机理。     

产气肠杆菌菌体内核苷磷酸化酶的诱导表达

目的:阿糖腺苷(Ara-A)是一种广谱抗病毒药物,临床上用于治疗多种病毒性疾病.同时也是合成阿糖腺苷单磷酸(Ara-AMP)的重要原料.本课题旨在寻找一种高效酶法生产嘌呤类阿糖核苷的方法.方法:以产气肠杆菌完整细胞为酶源,研究产气肠杆菌菌体培养条件对核苷磷酸化酶的影响及其诱导性.结果:胸苷磷酸化酶、尿苷磷酸化酶和嘌呤核苷磷酸化酶均可被多种核苷、核苷酸甚至碱基诱导.胞苷或胞苷酸的添加量为15-20mmol/L,诱导时间在0-8小时均可.经胞苷和胞苷酸诱导的菌体可使酶反应时间缩短6倍,大大提高了反应效率.经诱导的菌体,在反应后仍保持较高的核苷磷酸化酶活力;而未经诱导的菌体,一次反应后即丧失大量的酶活力.结论:核苷磷酸化酶的活性可以通过诱导而提高,以此优化阿糖腺苷的生产.     

聚酰胺色谱结合高速逆流色谱分离制备萹蓄黄酮类化合物

采用聚酰胺色谱结合高速逆流色谱法分离纯化了萹蓄中3种黄酮类化合物,建立了快速分离制备萹蓄中3种黄酮类化合物的方法。通过聚酰胺柱色谱富集黄酮类成分,再经过高速逆流色谱分离,以乙酸乙酯-甲醇-水-甲酸(体积比为4∶1∶5∶0.1)组成的二相系统作为固定相与流动相,在主机转速为850 rpm,流速为2.0m L/min,检测波长为254 nm的条件下制备样品。从150 mg富集黄酮成分的馏分中,一次性分离制备得到纯度为94.86%的杨梅树皮苷(myricitrin)7.5 mg,94.28%的黄芪苷(astragalin)13.8 mg,91.86%的合欢草素1(desmanthin-1)20.6 mg。所得馏分经高效液相色谱法(HPLC)检测纯度,并经MS和NMR鉴定化合物的结构。该方法简便、快速,所得产物纯度高,适合于黄酮类化合物的制备分离。     

代谢工程方法改造大肠杆菌生产胸苷

胸苷是抗艾滋病药物司他夫定(3′-脱氧-2′,3′-双脱氢胸苷)和叠氮胸苷的重要前体物质。应用代谢工程方法对大肠杆菌Escherichia coli BL21(DE3)生物合成胸苷进行了研究。通过敲除E.coli BL21嘧啶回补途径的deo A、tdk和udp三个基因,BS03工程菌株能够积累21.6 mg/L胸苷。为了增加合成胸苷前体物核糖-5-磷酸和NADPH的供给,进一步敲除pgi和pyr L使工程菌BS05胸苷的产量提高到90.5 mg/L。而通过过表达胸苷合成途径的ush A、thy A、dut、ndk、nrd A和nrd B六个基因,菌株BS08胸苷的产量能达到272 mg/L。通过分批补料发酵,BS08最终可以积累1 248.8 mg/L的胸苷。本研究结果表明经过代谢工程改造的E.coli BL21具有良好的胸苷合成能力和应用潜力。     

应用乙酰短杆菌酶法合成2''''-脱氧腺苷

胸苷和腺嘌呤在乙酰短杆菌作用下转化成胸腺嘧啶和目标产物2’-脱氧腺苷。50mL的三角瓶装液10mL,40mmol/L的底物,50mmol/L的磷酸盐缓冲液(pH7)进行反应,5%游离乙酰短杆菌在55℃下,经1h转化率就可达到65.6%。     

快速制备液相色谱分离库拉索芦荟中10-羟基芦荟大黄素苷(英文)

采用快速制备液相色谱从库拉索芦荟中高效分离制备10-羟基芦荟大黄素苷A和B。以库拉索芦荟药材粉甲醇提取物为原料,采用快速制备液相色谱,EYELA柱(300 mm×20 mm i.d.,20~45μm),甲醇-水为流动相(35∶65,v/v)等度洗脱,流速10 mL/min,检测波长356 nm,对芦荟样品进行分离制备,得到2种化合物单体,经UV、旋光度、HRMS和NMR鉴定,HPLC测定纯度,2个化合物分别为10-羟基芦荟大黄素苷B(98.9%)和10-羟基芦荟大黄素苷A(98.2%)。该方法简便、快速,所得产物纯度较高,可用于对照品的制备和药理毒理活性研究。     

高效液相色谱法在脱氧核糖核酸酶解动力学

为了更好地对脱氧核糖核酸酶解动力学过程进行研究,建立脱氧核糖核酸(DNA)酶解液中4种脱氧核苷酸(腺嘌呤脱氧核苷酸(dAMP)、鸟嘌呤脱氧核苷酸(dGMP)、胞嘧啶脱氧核苷酸(dCMP)、胸腺嘧啶脱氧核苷酸(dTMP))的高效液相测定方法,能将酶解液中4种脱氧核苷酸完全分离并准确定量.在此基础上,对DNA酶解的动力学进行初步研究,其反应机理为不存在底物和产物抑制的双底物顺序反应,动力学方程为x=1/bln(1+abt)(其中a=0.372 3ρ0-0.974;b=-0.049 3ρ20+1.115 3ρ0 - 1.110 3),该方程可以很好地描述DNA酶解过程,误差仅为3.31%.     

嗜麦芽黄单胞菌游离细胞催化合成α-熊果苷

研究了利用嗜麦芽黄单胞菌BT-112(Xanthomonas maltophilia BT-112)游离细胞生物催化合成α-熊果苷,系统探讨了温度、对苯二酚浓度、对苯二酚与蔗糖摩尔比、反应时间、转速、细胞浓度、磷酸缓冲溶液pH值和浓度对反应转化率的影响。最佳反应条件为:反应温度为25℃,菌体对对苯二酚的最大耐受度为30mmol/L,蔗糖和对苯二酚的摩尔比为20∶1,反应时间为45h,摇床转速为160r/min,细胞浓度为85g/L,磷酸缓冲溶液浓度为25mmol/L、pH值为8.0。在此条件下α-熊果苷转化率高达86.7%(以对苯二酚计算)。     

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.