雨生红球藻培养基的改良

近年来,雨生红球藻（ＨａｅｍａｔｏｃｏｃｃｕｓｐｌｕｖｉａｌｉｓＦｌｏｔｅｔＷｉｌｌ）作为一种获取天然虾青素的资源被广泛重视ｌ‘,‘１。目前,有关而生红球藻的研究主要集中于虾青素的积累机制、合成调控及其生物学功能‘）。关于雨生红球资生长调控方面的工作报道较少,还没有一个很理想的红球藻培养基【’］,从而在很大程度上阻碍了对雨生红球藻的深人研究与开发利用。雨生红球藻尤其是它的绿色游动细胞对环境ｐＨ值的改变较敏感,其生长状况与培养液的ｐＨ稳定性关系密切［‘”］,而目前较多采用的ＭＣＭ、ＢＢＭ和Ｂｔｈｌ…     

氮源对雨生红球藻绿色生长期细胞生长的影响

【背景】雨生红球藻(Haematococcus pluvialis)细胞能合成积累具有超强抗氧化活性的虾青素,是生产高值天然虾青素的优异藻种。【目的】解析不同氮源对雨生红球藻生长的效应,以期建立优化氮素营养提高雨生红球藻生物量和虾青素产量的技术体系。【方法】选用Na NO3和NH_4Cl为氮源、辅以pH缓冲液Hepes,培养雨生红球藻藻株797,测试2种不同氮源对雨生红球藻藻液pH、营养生长期(绿色生长期)藻细胞生长、叶绿素含量和生物量等的影响。【结果】以Na NO3为氮源培养的雨生红球藻细胞的比生长速率、生物量、叶绿素a和叶绿素b含量均高于以NH_4Cl为氮源培养的藻细胞。不同氮源对雨生红球藻培养液的pH值有显著影响,NH_4Cl氮源导致培养液pH值降低,然而Na NO3氮源则导致培养液pH值上升。添加pH缓冲液Hepes能有效稳定培养液的pH值,并促进雨生红球藻的生长,尤以NH_4Cl为氮源添加Hepes的效果更显著。不同氮源导致雨生红球藻营养生长阶段细胞的生长和生物量等差异主要源于不同氮源引起藻液pH的变化。【结论】添加pH缓冲液Hepes可有效控制藻液pH,进而显著促进以Na NO3和NH_4Cl为氮源的雨生红球藻营养生长阶段细胞的生长和生物量积累。     

硝酸钾缓解氯化钠胁迫蓝藻Anabaena 7120固氮的生理基础

营养液中添加适量ＫＮＯ３可在一定程度上缓解ＮａＣｌ对鱼腥藻固氮活性的抑制作用。暗处理或加光合抑制剂时,ＫＮＯ３对ＮａＣｌ胁迫的缓解作用便消失。供给外源蔗糖、提高ＣＯ２浓度、同时供给ＣＯ２和Ｎ２时,ＫＮＯ３对缓解ＮａＣｌ胁迫的作用则增高．同时供给Ｏ２和Ｈ２对ＫＮＯ３的缓解作用增高影响较小,而在厌氧（Ａｒ或Ｎ２中）或单加氧下,ＫＮＯ３的缓解效应则明显减弱或消失．     

CO_2浓度对雨生红球藻生理生化指标的影响

为了探讨雨生红球藻对不同CO_2浓度的响应,利用生理生化测定方法比较了两种CO_2浓度对雨生红球藻生长、色素含量、叶绿素荧光参数和两种碳代谢相关酶的影响。结果显示在雨生红球藻的绿色营养阶段,4倍空气CO_2浓度下培养的藻细胞密度是空气CO_2浓度下的3.08倍(第10天),与空气CO_2相比,较高CO_2培养藻的叶绿素和类胡萝卜素含量、胞外碳酸酐酶(CA)活性降低,非光化学淬灭(NPQ)显著升高,最大光能转化效率(Fv/Fm)、实际光化学量子效率(ФPSII)多显著升高,而光化学淬灭(q P)、核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubisco)活性无显著差异。在雨生红球藻的红色孢子阶段,4倍空气CO_2培养下的藻细胞密度显著降低,但虾青素含量提高了20.23%(第8天)。以上研究表明可以通过适当提高CO_2浓度来促进雨生红球藻的生长和虾青素的积累。     

雨生红球藻虾青素合成研究进展

虾青素是一种重要的次级类胡萝卜素,具有高活性的抗氧化功能,广泛应用于食品保健、医药、水产养殖等领域。雨生红球藻是一种在胁迫条件下能够大量积累虾青素的微藻。文中回顾了雨生红球藻虾青素的生物合成研究的进展,包括虾青素生物合成的诱导与调控、虾青素合成与光合作用及脂类代谢的关系等研究现状。     

几种热带雨林与荒漠植物暗呼吸作用对高CO_2浓度的响应

使用 Ｌ Ｉ６４００ 便携式光合作用测定系统测定了美国生物圈二号内长期生长在高 Ｃ Ｏ２ 浓度（＞ １５００μｍ ｏｌ／ｍ ｏｌ）下 ５种热带雨林植物与 ５ 种荒漠植物暗呼吸强度的变化。结果表明：在 ３５０～４００μｍ ｏｌ／ｍ ｏｌ下 ５ 种雨林植物的平均暗呼吸强度为（０５６±０１９）μｍ ｏｌ Ｃ Ｏ２／ｍ ２·ｓ;荒漠植物平均为（０９８±０７２）μｍ ｏｌ Ｃ Ｏ２／ｍ ２·ｓ。在 Ｃ Ｏ２ 浓度升高时大部分 Ｃ３ 植物暗呼吸作用升高,并呈一定的线形关系。当 Ｃ Ｏ２ 浓度加倍时,雨林植物暗呼吸强度升高６１％ ;荒漠 Ｃ３ 植物升高１３４％ ,而 Ｃ４ 植物变化不明显或略有下降。因而认为,长期高 Ｃ Ｏ２ 浓度可促进 Ｃ３ 植物的暗呼吸作用。     

雨生红球藻ZL-1生长和虾青素积累条件优化

分离鉴定了一株雨生红球藻ZL-1,比较了不同接种密度和吲哚乙酸浓度对其生长的影响;在此基础上,探究了不同浓度水杨酸和盐度对雨生红球藻虾青素积累的影响。结果表明:(1)接种密度为2.00×10~4 cell·mL~(–1)时,雨生红球藻生长快速,最终生物量达到最大值0.43 g·L~(–1);不动细胞比游动细胞更快的积累虾青素,高光诱导不动细胞得到最高虾青素产量为8.44 mg·L~(–1);IAA终浓度为1.5 mg·L~(–1)时,雨生红球藻生长速度最快,最终细胞密度和干重分别比对照组提高了24.28%和27.11%;(2)水杨酸具有缓解高光胁迫和促进虾青素积累的双重作用,15和25 mg·L~(–1)水杨酸诱导下,雨生红球藻生物量较高,虾青素产量分别比对照组提高了18.18%和18.94%;使用4‰的盐度胁迫雨生红球藻,虾青素产量较对照组提高了17.42%,但盐度也会引起藻细胞的漂白、死亡,导致生物量显著降低。     

活性氧对雨生红球藻生长及虾青素含量的影响

在雨生红球藻培养液中分别添加活性氧1O2、H2O2和·OH的诱生剂,通过测定细胞密度、叶绿素a含量、虾青素含量,研究了这三种活性氧诱生处理对雨生红球藻生长和虾青素含量的影响,初步探索了利用活性氧诱生剂提高雨生红球藻虾青素含量的可行性。实验结果表明,适当浓度的MB能够促进虾青素含量增加,当MB浓度为10-7mol·L-1时,虾青素含量达到5.27μg·mL-1,比对照显著提高。活性氧诱生剂对雨生红球藻生长有抑制作用,但MB的抑制作用小于H2O2和·OH诱生剂。     

抗生素对雨生红球藻无菌化培养的影响

采用8种常用抗生素对雨生红球藻进行无菌化处理,研究抗生素种类及浓度对雨生红球藻细胞生长的影响,以确定对雨生红球藻细胞无害并能抑制伴生杂菌生长的抗生素种类及使用浓度。结果表明:培养前期(0~8d)添加灰黄霉素(0.05 mg/m L)的抑菌效果最好,且对雨生红球藻细胞的生长抑制最小;培养中后期(8 d后),添加青霉素(0.05 mg/m L)所起到的抑菌效果较明显。另外,当分阶段添加灰黄霉素(0.05 mg/m L)和青霉素(0.025mg/m L)时,雨生红球藻细胞密度可达4.75×106个/m L(培养18 d),是空白对照实验组的1.8倍,且其抑菌效果明显优于使用单一抗生素。     

雨生红球藻质体球滴结构蛋白基因的克隆与原核表达

叶绿体或者有色体中的质体球滴结构(Plastoglobules)是多数植物的类胡萝卜素等次生代谢产物积累的场所,但在能大量积累虾青素的雨生红球藻中,这个结构一直没有得到确认。通过透射电子显微镜观察发现雨生红球藻的质体内确切存在plastoglobules结构;并通过RT-PCR结合RACE技术,从雨生红球藻cDNA文库中克隆到了与编码plastoglobules的结构蛋白(Plastoglobulin)具有高度同源性的基因序列全长,称做Hpgp基因;该基因的表达产物称之为雨生红球藻质体球滴蛋白(HPGP;Haematococcus plastoglobules pro-tein);并进一步利用原核表达系统将该编码基因进行原核诱导表达,用His-Tag蛋白分离纯化系统纯化到了目标蛋白,并用该His-Tag融合蛋白为抗原免疫实验兔,制备到了相应的一抗抗体,为下一步对该蛋白的功能阐明以及雨生红球藻的虾青素积累机制研究提供重要的基础。     

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.     

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.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

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).