用基因组改组技术改良发酵木糖酵母Candida tropicalis XY-19的耐乙醇性能

Candida tropicalis XY-19是一株具有优良乙醇发酵性能的发酵木糖酵母,其发酵葡萄糖产乙醇性能与目前酒精工业生产菌种--安琪酒精酵母相近,但XY-19的耐乙醇性能远比安琪酒精酵母差,XY-19在含有超过7%(v/v)乙醇的培养基中不能生长。以XY-19为出发菌株,经紫外线诱变获得了5株能在7.5%(v/v)乙醇的培养基中旺盛生长的突变株,经Co-60诱变获得了8株能在含8%(v/v)乙醇的培养基中旺盛生长的突变株。然后,以紫外线诱变得到的5株菌和Co-60诱变得到的8株菌及耐乙醇性能较好的酿酒酵母(S.cerevisae Angel,S.cerevisae4608和S.cerevisae172)为出发菌株,经过4轮Genome shuffling结合木糖乙醇梯度平板的筛选,获得了4株(G3-13,G3-18,G3-57和G3-60)能够在12%乙醇平板上生长的菌株,其乙醇耐受性比野生菌株XY-19提高了71%,为将XY-19进一步开发成纤维质乙醇发酵的生产菌种奠定基础。本研究结果进一步体现了Genome shuffling技术在改良如乙醇耐受性等多基因控制性状上的突出优势,为工业生产菌种的快速有效改良提供了一种有效的方法。     

高产Y-氨基丁酸酵母菌株的亚硝基胍诱变选育

目的：探讨亚硝基胍诱变选育高产Y-氨基丁酸酵母菌株的方法。方法：使用亚硝基胍对酵母菌株进行诱变;采用含溴甲酚绿的YEPD培养基筛选突变菌,采用薄层层析法和比色法鉴定变异菌株发酵液中的Y-氨基丁酸及其含量;对突变菌株连续继代培养4代,测定各代发酵液中Y-氨基丁酸的含量,鉴定诱变菌株的遗传稳定性：结果：亚硝基胍诱变酵母的最佳浓度为1．0g．L^-1,最佳诱变时间为15min;获得了5株突变菌株,菌落呈绿色;薄层层析法鉴定突变菌株都能产Y-氨基丁酸;诱变菌发酵液中的Y-氨基丁酸含量各异,但高于对照,且增长幅度很大;对突变菌株后代遗传稳定性进行了鉴定,结果表明突变菌株4遗传性较稳定。结论：采用1．0g．L^-1的亚硝基胍溶液处理酵母菌15min,经筛选鉴定,获得了一株遗传稳定的高产Y-氨基丁酸的酵母菌株。     

高产γ-氨基丁酸酵母菌株的亚硝基胍诱变选育

目的:探讨亚硝基胍诱变选育高产γ-氨基丁酸酵母菌株的方法。方法:使用亚硝基胍对酵母菌株进行诱变;采用含溴甲酚绿的YEPD培养基筛选突变菌,采用薄层层析法和比色法鉴定变异菌株发酵液中的γ-氨基丁酸及其含量;对突变菌株连续继代培养4代,测定各代发酵液中γ-氨基丁酸的含量,鉴定诱变菌株的遗传稳定性。结果:亚硝基胍诱变酵母的最佳浓度为1.0g.L-1,最佳诱变时间为15min;获得了5株突变菌株,菌落呈绿色;薄层层析法鉴定突变菌株都能产γ-氨基丁酸;诱变菌发酵液中的γ-氨基丁酸含量各异,但高于对照,且增长幅度很大;对突变菌株后代遗传稳定性进行了鉴定,结果表明突变菌株4遗传性较稳定。结论:采用1.0g.L-1的亚硝基胍溶液处理酵母菌15min,经筛选鉴定,获得了一株遗传稳定的高产γ-氨基丁酸的酵母菌株。     

适合甘蔗汁发酵高产酒精酵母的选育

目的:选育出适合发酵甘蔗汁生产燃料乙醇的高产酿酒酵母的菌株.方法:以酵母菌株 YS,作为出发菌株,将酶解破壁后获得的原生质体进行紫外诱变,通过初筛和复筛进行选育.结果:获得一株高产酒精的酿酒酵母突变株 YSs-1,该突变株发酵甘蔗汁的乙醇含量可达12.6%(V/V),较出发菌株的 11.6%(V/V)提高了 8.6%,其糖的转化率高达 94.5%,高于出发菌株的 87.0%.结论:通过 5 次连续传代培养后其突变株的乙醇产量保持稳定,表明该突变株完全可以用于发酵甘蔗汁生产燃料乙醇.     

耐温性L-谷氨酸发酵菌种的选育

应用基因组改组技术提高,L-谷氨酸生产菌在高温发酵条件下的谷氨酸产量。以天津短杆菌T6—13变异株SW07-1为原始亲株,分别经紫外线（UV）-硫酸二乙酯（DES）和X射线诱变,获得5株耐温性能略有提高的突变菌株。经2轮基因组改组,获得耐高温（能在44℃生长）的L-谷氨酸菌株F2-50。F2—50在38℃下,摇瓶发酵40h,发酵液中L-谷氨酸浓度比原始出发菌株提高了近41％,在41℃高温下,摇瓶发酵40h,L-谷氨酸浓度比原始出发菌株提高了近2倍。     

姬松茸原生质体诱变育种研究

以姬松茸原生质体为诱变材料,用不同诱变剂紫外线（UV）,钴60（Co^60）,亚硝基胍（NTG）进行多次反复诱变处理,获得2株活性多糖产量较高,遗传稳定的变异株C811/N516。与出发菌株各项发酵指标比较,突变株其他各发酵特性变化不明显,而单位发酵液活性多糖含量分别提高260%和300%以上。     

产耐高温谷氨酰胺转胺酶菌株的快速筛选方法

目的:采用亚硝基胍(NTG)诱变结合96孔板高通量筛选方法筛选产耐高温谷氨酰胺转胺酶(MTG)的茂原链霉菌(Streptomyces mobaraensis)。方法:通过优化96孔板高通量测定MTG活性的方法、确定筛选温度和时间,建立了产耐高温MTG菌株的快速筛选方法;通过优化NTG诱变条件建立了筛选突变库;通过96孔板高通量初筛、摇瓶复筛获得了产耐高温MTG的突变株12-82,并通过摇瓶发酵对12-82所产MTG进行热稳定性分析。结果:采用2mg/ml NTG、p H8.0、60min的诱变条件获得突变株,将突变株的发酵上清液于70℃水浴7.5min,再在37℃空气浴、反应10min的条件下测定MTG活性,从5 200株突变株中筛选出5株产耐高温MTG的突变株,其中突变株12-82在50℃水浴60min以及70℃水浴1.5min的酶活残留率均比出发株高出近20%,且80℃保温2min仍有11.9%的酶活残留率。结论:利用NTG诱变结合96孔板高通量筛选的方法筛选到5株所产MTG热稳定性相对较高的突变株,其中突变株12-82在50℃、70℃和80℃的酶活残留率均有10%~20%的提高。这为高温食品加工领域所需耐高温MTG生产菌株的高效筛选提供了可行性方案。     

基因组重排技术选育乙醇高产菌株

里氏木霉（Trichoderma reesei）被认为是最合适联合生物加工（consolidated bioprocessing）的微生物之一。原始里氏木霉菌株产乙醇能力太低,需要进一步提高其产酒量。我们通过基因组重排技术提高了里氏木霉菌株产乙醇能力和乙醇耐受力。首先对CICC40360菌株孢子进行NTG诱变得到正向突变菌株,再以此为出发菌株进行基因组重排。进行基因组重排后,重组菌株在含不同乙醇浓度的原生质体再生培养基上进行筛选。突变菌株和原始菌株一起做摇瓶发酵实验进行比较以确定产乙醇能力的提高。经过两轮基因组重排后,筛选获得表现最优异的重组菌S2-254。该菌株能在利用50g/l葡萄糖发酵出6.2g/l乙醇,同时能耐受3.5% （v/v）浓度乙醇。上述结果表明,本实验采用的基因组重排技术能够有效而且快速获得具有目的性状的优良菌株。     

C．shehatae TZ8耐乙醇菌株的筛选及发酵性能研究

以C.shehataeTZ8为出发茵株,利用1％溶壁酶和1％蜗牛酶酶解1．5h,制备成C.shehataeTZ8原生质体,并对原生质体进行紫外诱变,以含不同浓度乙醇的木糖液体培养基培养进行初筛和复筛,获得一株遗传性能稳定、耐乙醇能力达5．5％（v／v）的蕾株C．shehataeTZ8-4,比初始菌株耐乙醇能力提高了2％。对突变株C．shehataeTZ8-4发酵性能的研究结果表明：C．shehataeTZ8-4发酵糖能力从80g/L（葡糖糖和木糖比为2：1）提高到120g／L,最大乙醇产量从27．41g／L提高到43．12g／L。     

米根霉乙醇脱氢酶(ADH)突变菌株的诱变选育

米根霉发酵生产L-乳酸过程中,由于丙酮酸在丙酮酸脱羧酶、乙醇脱氢酶(ADH)催化下生成乙醇,使得丙酮酸向乳酸转化的流量减少。采用亚硝基胍(NTG)诱变米根霉AS3．3462孢子液,诱变剂量为0．15 mg/ mL时,致死率为70%～80%。在含丙烯醇的YPD筛选培养基上筛选获得两株ADH活力降低的突变株mut-1和mut-2,检测突变株mut-1和mut-2的最大ADH活力分别为35．67和43．09U/mL,是原始菌株的41．63%和50．29%。发酵72h后,原始菌株的乙醇与乳酸浓度分别为28．9g/L和40．31g/L,而mut-1和mut-2突变株的乙醇产量分别为4．87g/L和6．56g/L,乳酸产量为54．45g/L和44．07g/L。在相同的发酵条件下,米根霉ADH突变株mut-1和mut-2对还原糖的利用速率高于出发菌株,其生物量积累亦高于出发菌株。     

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.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

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.     

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).     

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.