温度和pH对B.s.C3—41菌株生长和毒力的影响

本文报道了不同培养温度和液体培养基的起始州值对球形芽孢杆菌Ｃ３－４１菌株的生长和毒力的影响绪果。在２０－４０℃下分别进行摇瓶发酵实验时,以３５℃下培养的发酵液菌数最高,杀蚊毒力最强,其生长周期最短;当将液体培养基ｐＨ分别调至５、６、７、８、９、１０在３０℃以２２０ｒ／ｍｉｎ进行摇瓶发酵时,证明在ｐＨ７下培养的发酵液毒力最强。     

一株芽孢杆菌在维生素C二步发酵中对小菌的促进作用

从土壤中分离到1株能更好促使小菌生长和产酸的芽孢杆菌B601,作为伴生菌与巨大芽孢杆菌相比,在生长过程中,发酵液中B601活菌数小于巨大芽孢杆菌,而其芽孢数则多于巨大芽孢杆菌。对B601组成菌系的发酵条件进行优化,得到如下结果：100g／L L-山梨糖、6g／L尿素、10g/L玉米浆、培养温度30℃和发酵周期44h。与巨大芽孢杆菌组成菌系相比其底物,L-山梨糖质量浓度提高了25％,尿素下降了50％．玉米浆质量浓度下降了33％,温度提高了2℃,发酵周期缩短了4h。结果表明：B601作为伴生菌,与巨大芽孢杆菌相比,该菌株明显提高了发酵效率。     

球形芽孢杆菌Mtx1杀蚊毒素在苏云金芽孢杆菌以色列亚种中的表达

将来源于球形芽孢杆菌SSII-1的mtx1毒素基因克隆至穿梭载体pBU4上,得到mtx1插入方向相反的重组质粒pMT9和pMT4.含有pMT9和pMT4的大肠杆菌转化子能表达产生Mtx1毒素,发酵液对敏感和抗性致倦库蚊幼虫具有中度毒杀作用;含有pMT9和pMT4的苏云金芽孢杆菌转化子B-pMT9和B-pMT4在营养体生长阶段对敏感蚊幼和抗性幼虫也具有毒性,毒力与野生型SSII-1相当,而不同转化子在芽孢形成期的毒力因插入的mtx1基因转录方向不同而表现出差异,其中B-pMT4对目标蚊幼毒力极低(LC50＞100mg/mL),而B-pMT9对蚊幼虫具有毒性(LC50=2.49mg/mL).     

球形芽孢杆菌C_3－41对致倦库蚊的毒效及在蚊体内的再循环

球形芽抱杆菌Ｃ３－４１菌株（Ｂａｃｉｌｌｕｓｓｐｈａｅｒｉｃｕｓ　Ｃ３－４１）对致倦库蚊（Ｃｕｌｅｘｑｕｉｎｑｕｅｆａ－ｓｃｉａｔｕｓ）幼虫有很高毒效,对２龄和３—４龄幼虫的半致死剂量（ＬＤ５０）分别为６３．１和８９．７芽孢／蚊幼虫。处理浓度越高,取食时间越长,蚊幼虫取食到的杀蚊活性物质量越多,死亡率越高。当蚊幼虫取食互致死剂量杀蚊活性物质后,球形芽孢杆菌在感染的活幼虫体内不增殖;但当蚊幼虫取食致死剂量杀蚊活性物质后,蚊幼死亡,球形芽抱杆菌在死蚊幼虫体内增殖明显,６天内芽抱从感染初期的１．８６×１０２／蚊幼虫增加到１．５９×１０６／蚊幼虫。芽抱在死蚊幼虫体内能正常荫发、生长、产孢和形成毒素。增殖的芽抱同样对致倦库蚊幼虫有较高毒力。     

利用芽孢菌发酵废水培养小球藻的研究

研究表明,在25℃、光照12h／d（4500lx）条件下,芽孢茵发酵废水对小球藻的生长有促进作用,且促进作用随废水浓度的升高而增强。浓度为10％Ya发酵废水对小球藻的促进增殖作用与对照组相近,纯发酵废水培养的小球藻最高密度为对照组的7．4倍。研究同时表明,小球藻对芽孢菌发酵废水有较强的降解能力,通过10d的培养,发酵废液中的COD下降95．53％,氨态氮下降81．27％,亚硝酸盐氮下降88．33％。     

苏芸金杆菌以色列变种对尖音库蚊的毒杀作用

苏芸金杆菌以色列变种(Bacillus thuringtensis var.tsraelensis de Barjac)对尖音库蚊(Culex pipiensvar. pallens Coq uillett)三龄幼虫具有极高的毒性,在浓度为1.5×10⁴芽孢/毫升时,死亡率达100%。其他几个变种B. T. var. thuringiensis(E—009)var. kurstaki(HD—1)、var.kenyae(7404)、var. ostriniae(006)浓度达4×10⁵芽孢/毫升时仍未见毒效。 用液体双相与等密度离心法将以色列变种的晶体与芽孢分离,分别研究晶体(纯度达99.5%以上)、芽孢(纯度达99.5%以上)对尖音库蚊幼虫的毒性。发现使蚊幼虫致死主要是晶体LC₅₀为0.023微克/毫升,芽孢也具有毒性LC₅₀为0.86微克/毫升,晶体与芽孢混用制剂的LC₅₀为(0.014微克晶体+0.014微克芽孢)/毫升。 晶体制剂在30℃和21℃的温度条件下毒力没有变化,但芽孢制剂在21℃毒力显著下降;芽孢制剂致死幼虫,立即用相差显微镜镜检,发现肠道内有大量正在萌发的芽孢,对芽孢致死的原因进行了初步分析。     

球形芽孢杆菌Mtx1杀蚊毒素在苏云金芽孢杆菌以色列亚种中的表达*

将来源于球形芽孢杆菌SSII 1的mtx1毒素基因克隆至穿梭载体 pBU4上 ,得到mtx1插入方向相反的重组质粒 pMT9和pMT4。含有 pMT9和 pMT4的大肠杆菌转化子能表达产生Mtx1毒素 ,发酵液对敏感和抗性致倦库蚊幼虫具有中度毒杀作用 ;含有pMT9和pMT4的苏云金芽孢杆菌转化子B pMT9和B pMT4在营养体生长阶段对敏感蚊幼和抗性幼虫也具有毒性 ,毒力与野生型SSII 1相当 ,而不同转化子在芽孢形成期的毒力因插入的mtx1基因转录方向不同而表现出差异 ,其中B pM     

青霉素酶发酵液的预处理和酶学特性

研究了在发酵液中添加絮凝剂对发酵液进行预处理,对蜡状芽孢杆菌（Bacillus cereus）产生青霉素酶的影响与酶学特性。实验结果表明,发酵液膜处理的难易程度与芽孢释放程度成正相关,在发酵液中添加0．02g／mL自制絮凝剂进行预处理,过滤效率提高10倍,而酶活损失仅5％;酶学特性研究结果表明,该酶最佳反应温度55℃时,酶的最适反应pH值7．0,金属离子锌、锰、镁对酶有激活作用,其浓度为0．25moL／L;酶热稳定性研究结果表明,在75℃下保温30min时,酶活损失85％。该酶在过量青霉素底物下,酶促反应为0级反应。     

中国Bt Ken－Ag最佳发酵培养基的优选及其发酵生理学研究

用正交试验方法选出ＢｔＫｅｎ－Ａｇ菌株的发酵培养基Ｍ３和ＦＢＨ２两个配方,其发酵液菌数可稳定的保持７０亿／ｍｌ,芽孢晶体形成率达８０－９０％,用ＦＢＨ２配方,对棉铃虫的毒力效价在２０００ＩＵ／μｌ以上。同时研究了在发酵培养基上的生长,ｐＨ变化、芽孢晶体形成以及糖、氮的代谢情况。     

球形芽孢杆菌C3—41二元毒素基因在苏云金芽孢杆菌以色列亚种中的？…

球形芽孢杆菌Ｃ３－４１是我国分离的一株对蚊幼虫有毒杀作用的高毒力菌株,对库蚊、按蚊幼虫的毒性高于２３６２菌株,Ｓｏｕｔｈｅｒｎ杂交证明Ｃ３－４１总ＤＮＡ中３．５ＫｂＨｉｎｄＩＩＩ片段上带有４１．９和５１．４ｋＤ二元毒素基因。     

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.     

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     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various