细菌3—脱氧葡糖松还原酶产生菌及产酶条件

从１２株细菌菌株中筛选到一株产３－脱氧葡糖松还原酶的高产菌Ｂａｃｉｌｌｕｓｓｐ．２并研究了该菌株的产酶条件。在所试验的细菌中,３－脱氧警戒松氧化酶活性较低甚至检测不出,而还原酶活性普遍较高。     

3-脱氧葡糖松代谢酶产生菌的筛选及产酶条件

从霉菌和酵母中筛选到一株酵母（Saccharomycescerevisiae231）,该菌株具有能够代谢3-脱氧葡糖松（3－deoxyglucosone）的酶,且活性较高。研究了该菌株的最适产酶条件：培养温度28℃,培养基起始pH7.0,培养时间12h,碳源、氮源分别为蔗糖、牛肉膏,添加KH₂PO₄、Ca（H₂PO₄）₂·H₂O能促进产酶。     

产低温脂肪酶非极端细菌的筛选、产酶发酵及粗酶性质研究

目的：筛选产低温脂肪酶非极端细菌菌株,扩大脂肪酶的应用范围。方法：利用维多利亚蓝B平板显色法和摇瓶发酵法,从土壤中筛选产脂肪酶菌株,通过菌落形态和菌体特征观察初步对菌种进行鉴定,并对该菌株的产酶发酵培养基进行了优化。结果：得到一株产低温脂肪酶非极端细菌菌株sybc—li一1,该菌株适宜产酶培养基（％）为淀粉1、牛肉浸膏1、NaNO3 0．08、CaCl2 0．04、MgSO4 0．04、橄榄油2和OP1;初始DH8、30℃、200r／min培养72h,脂肪酶活力可高达到30．2U／mL;所产脂肪酶粗酶最适作用温度20℃,最适pH9．5,0℃时仍能保持70％的酶活性,属于低温酶;该酶与目前报道的低温脂肪酶相比,有较好的热稳定性,粗酶在pH8．5、70℃条件下保温60mla,酶活力损失30％。结论：该菌株为自然环境中筛选的非极端细菌,所产脂肪酶为低温脂肪酶,在开发应用上有良好的前景。     

3—脱氧铺糖松代谢酶产生菌的筛选及产酶条件

从霉菌和酵母中筛选到一株酵母,该菌株具有能够代谢３－脱氧葡糖松的酶,且活性较高,研究了该菌株的最适产酶条件：培养温度２８℃,培养基起的ＰＨ７．０,培养时间１２ｈ,氮源分别为蔗糖,牛肉膏、添加ＫＨ２ＰＯ４、Ｃａ（Ｈ２ＰＯ４）２,Ｈ２Ｏ能促进产酶。     

假丝酵母尿酸酶形成条件

选出了一株产尿酸酶的产朊候丝酵母(Candida utilis)AS2．117。此菌株尿酸酶形成条件的研究表明：尿酸、黄嘌呤和鸟嘌呤对酶形成起诱导作用;玉米浆对菌株生长和酶形成起十分重要的作用;蔗糖、葡萄塘、D-甘露糖和果糖是酶形成的适合碳源;生物素对酶产生有促进作用;在含有玉米浆培养基中加入无机氮源对产酶无作用,添加有机氮略增加产酶量。尿酸酶形成最适培养基组成为(％)：蔗糖;,玉米浆3,尿酸0．1,蛋白胨0．1,生物素0．05,KCI0．1,NaCl 0.1。最适pH为6．2。在250ml三角瓶中装30ml培养基为最适。在200r／min的旋转摇床上25℃振荡培养21h,在此条件下最终酶活力可达0．6u／ml。     

苯甲酸1，2-双加氧酶高活力菌株的筛选和发酵条件的研究

从176株细菌中,筛选出苯甲酸1,2-双加氧酶的高活力菌株假单胞菌(Pseudomonas)137。进行了该菌产酶的发酵条件试验。产酶的最适温度为32℃,最适起始pH为6．5—7．0。葡萄糖、麦芽糖和甘油对产酶有明显的抑制作用,苯甲酸钠对产酶有促进作用。氨态氮对菌体生长和产酶是必需的。琥珀酸钠是酶形成的有效诱导物,采用0．1％苯甲酸钠和0．2％琥珀酸钠培养基(pH6．5—7．0),于32℃振荡培养72小时,可获得高活力的苯甲酸1,2-双加氧酶,每克菌体酶活力可达5-8单位。     

产3-脱氧葡糖醛酮代谢酶微生物的研究*

从海洋细菌中筛选到一株产３－脱氧葡糖醛酮代谢酶活力较高的菌株Ｆｓ－４—Ｃ－３,并对其进行了最适产酶条件的研究。实验证明：以鱼肉蛋白胨为氮源、蔗糖为碳源,在培养基起始ｐＨ值为７．８～８．０,温度为２８℃,盐度为５％的情况下,培养９６ｈ,产酶最高。３－ＤＧ可以诱导产酶。     

产3—脱氧葡糖醛酮代谢酶微生物的研究

从海洋细菌中筛选到一株产３－脱氧葡糖醛酮代谢酶活力较高的菌株Ｆｓ－４－Ｃ－３,并对其进行了最适产酶条件的研究。实验证明：以鱼肉蛋白胨为氮源、蔗糖为碳源,在培养基起始ｐＨ值为７．８～８．０,温度为２８℃,盐度为５％的情况下,培养９６ｈ,产酶最高,３－ＤＧ可以诱导产酶。     

高活力β-淀粉酶菌种的选育和发酵条件的研究

产β一淀粉酶的腊状芽孢杆菌(Bacillus cereus)Asl．447,通过紫外线、亚硝基胍和利福平的反复处理诱变,获得一株具有高活力β-淀粉酶的变异菌株M一3,产酶活力从74u／ml提高到5000—7000u／ml。牛肉汁液体培养基成分为：每100ml牛肉汁中加人蛋白胨1g,可溶性淀粉1g,酵母膏0．5g,NaCl 0．5g pH6．0。该变异菌的最适培养条件是：pH6—6．5 30℃48小时。酶的最适反应条件是：温度40℃,pH7 0,pH稳定范围是6—9,酶的抗热性较差,对可溶性淀粉水解率达85％以上。     

一株产碱性蛋白酶菌株的选育及其发酵条件的研究

从土壤中分离到的553株芽孢杆菌中选出一株产蛋白酶活力较高菌株,经紫外线和亚硝基胍诱变,获得一株产碱性蛋白酶的菌株,酶活力可达10000u／m1,此菌株经鉴定为地衣状芽孢杆菌(Bacillus licheniformis)。适宜的发酵条件：培养基由6％玉米粉(山芋粉或葡萄糖),4％豆饼粉(或其水解液),Na,HP0．·12Hz0 0．4％,KH：P0·0．03％,Na zc0,0．1％组成,pH7．O,37℃旋转摇床振荡培养{2一q6小时。酶作用的最适条件：60℃,pH9．0一10．5,在pH6．0—10．5范围内稳定。酶受DFP抑制。     

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.