温度对雨生红球藻（Haematococcus pluvialis）生物量和虾青素产量的影响

在用环形培养池模拟系统培养雨生红球藻的过程中,研究了温度对雨生红球藻生物量及虾青素产量的影响。结果表明,在15～25℃的范围内,不同温度下雨生红球藻生物量和虾青素含量及产量都经历了一个上升一最高一下降的过程。25℃与22℃时红球藻的虾青素产量、虾青素含量(干重)均显著高于其他温度的(P＜0．01),但两者间差异不显著(P＞0．05)。15℃时,红球藻生物量、虾青素含量和虾青素产量均最低,分别为1．4g、0．54％和2．49mg／L,25℃时,红球藻生物量和虾青素产量最高,分别为2．68g和13．53mg／L,22℃时,虾青素含量最高,为1．52％。     

温度对雨生红球藻(Haematococcus pluvialis)生物量和虾青素产量的影响

在用环形培养池模拟系统培养雨生红球藻的过程中,研究了温度对雨生红球藻生物量及虾青素产量的影响。结果表明,在15～25℃的范围内,不同温度下雨生红球藻生物量和虾青素含量及产量都经历了一个上升—最高—下降的过程。25℃与22℃时红球藻的虾青素产量、虾青素含量(干重)均显著高于其他温度的(P<0.01),但两者间差异不显著(P>0.05)。15℃时,红球藻生物量、虾青素含量和虾青素产量均最低,分别为1.4g、0.54%和2.49mg/L;25℃时,红球藻生物量和虾青素产量最高,分别为2.68g和13.53mg/L;22℃时,虾青素含量最高,为1.52%。     

黄腐酸对雨生红球藻虾青素的积累和CHY基因表达量影响

实验以雨生红球藻Haematococcus pluvialis LUGU为对象,研究了不同浓度的黄腐酸对微藻细胞生长、虾青素积累以及β-胡萝卜素羟化酶(CHY)基因表达量的影响。结果表明,FA浓度为5 mg/L,藻细胞生物量产率达到了79.39 mg/(L·d),虾青素产量达到了20.82 mg/L,分别比对照组提高了4.25%和86.89%;FA浓度为10 mg/L,藻细胞的生物量产率和虾青素产量分别比对照组提高了5.44%和9.78%。RT-PCR分析显示,虾青素合成的关键基因CHY的表达受FA的诱导,当添加5和10 mg/L的黄腐酸时,CHY基因最大的表达量分别为对照的18.1倍和7.3倍,当添加20 mg/L的黄腐酸时CHY基因的最大的表达量仅为对照的3.2倍,FA诱导下的雨生红球藻虾青素的积累含量和CHY基因表达量呈正相关。实验表明,适当浓度的黄腐酸不仅能够显著提高虾青素合成关键酶基因CHY的表达水平,并且明显促进了藻细胞内虾青素的积累,因此黄腐酸可作为虾青素生产的一种有效诱导子。     

红球藻研究进展

红球藻是一种生活于间歇性水体的淡水绿藻,能大量积累类胡萝卜素(可占干重的2%-5%),其中80%以上为虾青素(Astaxanthin)及其酯类1-3.近年来,虾青素在水产养殖中(如虹鳟、鲑等的人工养殖)较广泛地用作饲料添加剂,取得了满意的着色效果4-6.另一方面,虾青素的抗氧化能力强于β-胡萝卜素7和维生素E8,具有潜在的医用价值。       

雨生红球藻抗氧化系统对活性氧的清除机制

雨生红球藻(Haematococcus pluvialis)是一种淡水单细胞绿藻,隶属绿藻门、团藻目、红球藻科、红球藻属。它受强光、氮饥饿、高盐等胁迫时积累大量的虾青素,含量可高达细胞干重的6.0%以上[1]。相关研究也显示来虾青素具有极强的抗氧化活性[2—4],它的抗氧化活性较α-生育酚强千倍[5],比维生素E高近百倍[6]。雨生红球藻产生     

外源2,6-二叔丁基对甲酚对非生物胁迫条件下雨生红球藻虾青素积累的影响

【背景】雨生红球藻是天然虾青素的最佳来源,广泛应用于虾青素的工业化生产。【目的】探究外源添加不同浓度的2,6-二叔丁基对甲酚(Butylated hydroxytoluene,BHT)对雨生红球藻虾青素积累的影响,以期建立BHT提高雨生红球藻虾青素产量的技术体系。【方法】选用不含硝态氮的BBM培养基,辅以强光照,培养雨生红球藻(Haematococcus pluvialis)LUGU,测试不同浓度BHT对雨生红球藻生物量、虾青素含量、活性氧、抗氧化系统和虾青素合成相关酶基因的影响。【结果】在0-3 mg/L BHT范围内,2 mg/L BHT对雨生红球藻虾青素积累的促进效果最佳,达到31.66 mg/g。2 mg/L BHT有效降低了雨生红球藻内的活性氧水平,增加了细胞内NO水平,提高了藻细胞内过氧化氢酶(Catalase,CAT)、过氧化物酶(Peroxidase,POD)和超氧化物歧化酶(Superoxidedismutase,SOD)活性以及谷胱甘肽(Glutathione,GSH)的含量,诱导了虾青素合成关键酶基因chy和lcy的高效表达。【结论】非生物胁迫条件下,外源添加适量的BHT能促进雨生红球藻中虾青素的积累,且与藻细胞内的信号分子活性氧(Reactive oxygen species,ROS)、NO水平及虾青素合成相关基因的表达调控相关。     

2,4-二氯苯氧乙酸(2,4-D)对雨生红球藻中虾青素积累的影响

本文初步研究了一定浓度范围内的2,4-D对雨生红球藻积累虾青素的影响.在对数生长 期的藻液中分别加入一系列不同浓度的2,4-D溶液,然后进行胁迫培养(25℃、24h、5000Lx连续光照 营养盐饥饿),诱导细胞内虾青素的合成积累.在诱导过程中,显微观察不同浓度2,4-D处理后细胞形态和虾青素积累的动态变化,并定期取样测定虾青素含量.结果表明,20.0mg/L的2,4-D能够明显促进雨生红球藻中积累虾青素.它不仅可以加快虾青素积累进程(比对照提前15 d),而且比对照能提高13.4%的虾青素产量.     

UV-B对雨生红球藻生长及虾青素积累的影响

以雨生红球藻(Haematococcus pluvialis)为材料, 研究不同强度的UV-B对雨生红球藻生长、光合作用及虾青素积累的影响和其作用机理。设置5种紫外线强度, 分别在正常光照培养条件下补充不同强度UV-B(100—500 lx), 标记为CK、U100、U200、U300、U400和U500六组。结果表明, 经UV-B辐射后雨生红球藻细胞密度、PSⅡ最大光化学效率(F_v/F_m)、非光化学淬灭系数(NPQ)和叶绿素(Chl.a和Chl.b)含量等均呈现下降趋势, 且与辐射强度相关。相反, 虾青素含量在100—400 lx强度下随UV-B辐射强度的增加而升高。与对照相比, 高强度UV-B辐射(U400)36h和72h后藻细胞虾青素含量分别提高了35.68%和56.23%, 达到5.82和7.06 mg/L。qRT-PCR检测发现雨生红球藻虾青素合成关键酶基因(IPI、PSY、BCH和BKT)的表达量随紫外辐射强度和辐射时间的增加均有不同程度升高。UV-B辐射亦调控紫外光受体UVR8及其信号转导通路核心元件(COP1、SPA1、HYH和HY5)的基因表达, 暗示上述基因参与了UV-B诱导雨生红球藻虾青素积累的过程。研究揭示紫外光受体UVR8介导的信号转导通路可能参与虾青素合成的转录调控, 为建立应用UV-B辅助光源促进雨生红球藻富集虾青素的工艺提供了基础, 同时为解析光诱导雨生红球藻虾青素积累的转录调控机制提供了新的视角。     

褪黑素对非生物胁迫下雨生红球藻中虾青素积累的影响

以雨生红球藻Haematococcus pluvialis LUGU株为研究对象, 研究在高光照和缺氮胁迫条件下, 添加不同浓度褪黑素(melatonin, MLT)对雨生红球藻生长、虾青素积累、活性氧(ROS)、信号分子及dxs基因表达量的影响。结果表明, 外源添加10 μmol/L MLT可有效提高藻细胞中虾青素的含量, 最高可达31.32 mg/g, 是对照组(13.27 mg/g)的2.36倍; 抑制了细胞内ROS水平, 上调了信号分子一氧化氮(NO)和水杨酸(SA)的含量; 此外, dxs基因表达水平比对照组明显提高, 最高达11.3倍。研究表明, 在非生物胁迫条件下, 雨生红球藻中虾青素的大量积累可能与外源MLT调控细胞内ROS、信号分子及基因表达有关。     

雨生红球藻虾青素酰基转移酶的鉴定与功能研究

为研究雨生红球藻(Haematococcus pluvialis)的甘油二酯酰基转移酶(Diacylglycerol acyltransferase, DGAT)是否具有催化虾青素酰基化的功能, 首先通过雨生红球藻的cDNA库克隆得到了一个II型DGAT编码区全长序列(DGTT2)。在甘油三酯(Triacylglycerol, TAG)合成缺陷型酵母Saccharomyces cerevisiae H1246中过表达DGTT2基因发现HpDGTT2不能回补H1246的表型, 即不具有典型的DGAT功能。利用分离得到的雨生红球藻的内质网成功地建立了一个体外的虾青素酰基转移酶酶活测定体系, 添加含有重组HpDGTT2的酵母细胞的微粒体后虾青素酯的含量显著高于对照, 初步表明HpDGTT2具有催化雨生红球藻中虾青素酰基化功能。以上结果为进一步探索雨生红球藻中DGTT2的功能及深入理解虾青素合成在代谢水平的调控奠定了基础。     

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.