耐碱性芽孢杆菌碱性淀粉酶的研究：Ⅱ.菌株的诱变与产酶条件

耐碱性巨大芽孢杆菌（Ｂａｃｉｌｌｕｓ ｍｅｇａｔｅｒｉｕｍ）９－Ａ２经紫外线、甲基磺酸乙酯和硫酸二乙酯等多次诱变处理,获得一株产碱性α－淀粉酶能力较高的变异株Ｌ－４９。Ｌ－４９菌株比出发株的产酶能力提高近２．５倍,当以酵母膏为氮源,可溶性淀粉为碳源,初始ｐＨ９￣１０,种龄１８ｈ,接种量５％（Ｖ／Ｖ）,３０℃培养４８ｈ,酶活力可达７３０μ／ｍｌ。     

洗涤剂用碱性纤维素酶的研究（Ⅰ）：产酶菌种的选育及发酵条件

从土壤中分离获得碱性纤维素酶产生菌嗜碱芽孢杆菌ＳＨＹ８－１，经紫外线，亚硝基胍，甲基磺酸乙酯诱变及反复的自然分离和压力选择，获得高产变异株ＳＨＹ８－５７２５，产酶量由０．８９８ｕ／ｍｌ提高到１５－２０ｕ／ｍｌ，对影响产酶的各因素进行了分析测试。     

从万古霉素抗性突变体中筛选碱性纤维素酶高产菌株

以芽胞杆菌 Ｘ—６ 为出发菌株,经甲基磺酸乙酯（ Ｅ Ｍ Ｓ） 和紫外线（ Ｕ Ｖ） 复合诱变,选育万古霉素抗性突变体。研究结果表明,抗药性突变株碱性羧甲基纤维素酶（ Ｃ Ｍ Ｃａｓｅ） 产量提高的正变率和正变幅度明显高于非抗药性菌株。从抗性突变株中获得 Ｅ Ｖ２３ 菌株,其产酶活力比出发株 Ｘ—６ 提高３２０ ％ ,酶活力达３５３ｕ／ ｍｌ。     

洗涤剂用碱性纤维素酶的研究(I)——产酶菌种的选育及发酵条件

从土壤中分离获得碱性纤维素酶产生菌嗜碱芽孢杆菌ＳＨＹ８－１,经紫外线（ＵＶ）、亚硝基胍（ＮＴＧ）、甲基磺酸乙酯（ＥＭＳ）诱变及反复的自然分离和压力选择,获得高产变异株ＳＨＹ８－５７２５,产酶量由０．８９８ｕ／ｍｌ提高到１５～２０ｕ／ｍｌ,对影响产酶的各因素进行了分析测试。     

碱性淀粉酶产生菌的筛选和产酶条件的研究

对采自全国各地的５０份上样进行筛选,获得一株产酶活性较高的菌株Ｂ－９５４５,通过摇瓶培养确定了产酶的最适培养基Ⅱ（ｇ／１００ｍｌ）：复合蛋白胨１．０;玉米淀粉１．５;玉米浆１．５;ＮａＣ１０．５;Ｋ２ＨｐＯ４０．１;ＭｇＳＯ４０．０２;ＣａＣＯ３０．５;Ｔｗｅｅｎ８００．１;ｐＨｇ—１０,在该条件下,３０℃荡培养４８ｈ,酶活力可达５９６ｕ／ｍｌ。对菌株Ｂ—９５４５的产酶特性研究表明：该酶对高ｐＨ环境有较强的适应性,因此,可用于碱性洗涤用酶。     

紫外线诱变选育碱性蛋白酶高产菌株

本实验以枯草杆菌A4－3为出发菌株,发酵产生碱性蛋白酶,其野生型菌株产酶为2412u／ml。采用孢子热处理方法处理出发菌株孢子,得到变异株As—4,产酶2732．8u／ml。对As—4菌株进行紫外线绣变处理1min,得变异菌株AX—46,产酶为3213．8u／ml,且产酶能力稳定。     

复合诱变黑曲霉选育β—葡萄糖苷酶高产菌株

对黑曲霉原生质体进行紫外、ＬｉＣｌ复合诱变,观察诱变后原生质体再生菌落,发现了孢子色变异较大的菌株,且其变化与酶产量相关。经发酵筛选,获得β－葡萄糖苷酶活较高菌株,其酶活由出发菌株的１０ｕ／ｍｌ提高到１４．７ｕ／ｍｌ。再对高产突变株进行氮离子注入,酶活又提高２０％（达１７ｕ／ｍｌ）。     

产碱性纤维素酶菌株的选育和酶合成基本特性

芽孢杆菌ｘ－６菌株经甲基磺酸乙酯（ＥＭＳ）和紫外线（ＵＶ）复合诱变,以其万古霉素抗性突变体中选育获得一突变株ＥＶ２３,所产生的纤维素酶碱性酶,且酶活力由原来的０．８４Ｕ／ｍｌ提高到３．５３Ｕ／ｍｌ,ＥＶ２３菌株基本上组成性地合成碱性羧甲基纤维素酶（ＣＭＣａｓｅ）酶合成明显表现出抗降解物阻遏的特点,以葡萄糖为碳源培养,４％浓度时酶合成水平达最高,酶合成与生长几乎同时发生,合成效率受菌体生长速率影响较     

碱性蛋白酶产生菌的筛选及发酵条件考查

从土壤中分离到的167株芽胞杆菌中选出一株高产、稳产碱性蛋白酶菌株A4－3（嗜碱性枯草芽胞杆菌）。该菌株最适产酶条件为（g／100ml）：蔗糖6．0;豆饼水解液10.0;Na2CO31．0;起始pH9．5。在该条件下,经37℃振荡培养48h,酶活力达2612u／ml。     

柚苷酶产生菌的选育及发酵条件研究

根据柚皮苷的物理及化学特性,设计和试验了一种新的柚苷酶产生菌筛选模型。在１５３株曲霉中筛选到一株产柚苷酶菌株ＡｓｐｅｒｇｉｌｌｕｓｎｉｇｅｒＺＧ８４,摇瓶发酵酶活力为３２０ｕ／ｍｌ。经自然分离和ＤＥＳ诱变处理,得到ＺＧ８６菌株,酶活力达１１２４ｕ／ｍｌ。对其培养条件和产酶条件进行了研究。     

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.     

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.     

Synthesis and antimicrobial studies of hydrazone derivatives of 4-[3-(2,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid and 4-[3-(3,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid

Microbial resistance to antibiotics is an unresolved global concern, which needs urgent and coordinated action. One of the guidelines of the Centers for Disease Control and Preventions (CDC) to combat antibiotic resistance is the development of new antibiotics to treat drug-resistant bacteria. In our effort to find new antibiotics, we report the synthesis and antimicrobial studies of 30 new pyrazole derivatives. These novel molecules have been synthesized by using readily available starting materials and benign reaction conditions. Some of these molecules have shown activity with MIC values as low as 0.78?µg/mL against four bacterial strains; Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, and Acinetobacter baumannii. Furthermore, active molecules are non-toxic to mammalian cell line.

     

Novel compounds with potent CDK9 inhibitory activity for the treatment of myeloma

Cyclin-dependent kinases (CDKs) and Polo-like kinases (PLKs) play key role in the regulation of the cell cycle. The aim of our study was originally the further development of our recently discovered polo-like kinase 1 (PLK1) inhibitors. A series of new 2,4-disubstituted pyrimidine derivatives were synthesized around the original hit, but their PLK1 inhibitory activity was very poor. However the novel compounds showed nanomolar CDK9 inhibitory activity and very good antiproliferative effect on multiple myeloma cell lines (RPMI-8226).