植物甜味蛋白和矫味蛋白生物技术研究开发现状和前景

与蔗糖类甜味剂比较 ,植物甜味蛋白有很多优点 ,例如 :甜度高、热卡低、不引起龋齿以及可供糖尿病人食用等。迄今已知的植物甜味蛋白和矫味蛋白有 7种 ,即 :沙马汀 (Ｔｈａｕｍａｔｉｎ)、莫乃灵 (Ｍｏｎｅｌｌｉｎ)、马宾灵 (Ｍａｂｉｎｌｉｎ)、潘塔亭 (Ｐｅｎｔａｄｉｎ)、布拉齐因(Ｂｒａｚｚｅｉｎ)、库克灵 (Ｃｕｒｃｕｌｉｎ)和神秘果素 (Ｍｉｒａｃ ｕｌｉｎ)。这些植物甜味蛋白或矫味蛋白均来自热带雨林植物的果实。热带国家的居民常用其作为食物的增甜剂。近年来 ,在生物技术学家的努力下 ,又对这些甜味蛋白和矫味蛋白进行了克隆…     

甜味蛋白及其基因工程

甜味蛋白（ｔｈａｕｍａｔｉｎ）是从一种热带植物ＴｈａｕｍａｔｏｃｏｃｕｓｄｅｎｉｅｌｉＢｅｎｔｈ的胶质假种皮中分离出来的,该植物为竹芋科（Ｍａｒａｂｔａｃｅａｅ）的一种多年生灌木,广泛生长在西非的雨林中。甜味蛋白被认为是世界上已知的最甜的物质,大约２...     

博莱霉素A_5、Fe~（2＋）、O_2混合的化学发光研究

利用超弱发光仪测得博莱霉素Ａ５（ＢＬＭＡ５）、Ｆｅ２＋、Ｏ２混合物有微弱化学发光,最大发射波长约为５９０ｎｍ;发光强度随ＢＬＭＡ５或Ｆｅ２＋浓度增大而增强;·ＯＨ清除剂甘露醇对发光无影响;Ｃｕ２＋、ＥＤＴＡ、ＤＮＡ对化学发光均有不同程度的抑制作用。上述结果说明：ＢＬＭＡ５与Ｆｅ２＋、Ｏ２混合可形成某种激发态复合物,并显示该激发态的形成与·ＯＨ无关,提示该激发态复合物可能是ＢＬＭＡ５降解ＤＮＡ的启动因子。     

藏红花愈伤组织诱导及其细胞培养的研究

藏红花幼叶愈伤组织的诱导频率在ＭＳ,Ｂ５和Ｗｈｉｔｅ三种培养基上均高达９８％;幼叶和芽的诱导率差异不大,高达９９％;不同时期的叶片差异较大,以幼叶诱导为佳;球茎诱导率为近８０％;激素配比以２．４－Ｄ２．０ｍｇ／Ｌ,ＢＡＰ０．１～０．５ｍｌ／Ｌ为宜。在继代培养阶段,ＭＳ比Ｂ５和Ｗｈｉｔｅ更适合细胞的快速生长繁殖;并且以叶片的愈伤组织生长较快,芽次之,球茎最慢,适合于细胞生长的激素配比为ＮＡＡ２．０～３．０ｍｇ／Ｌ,ＢＡＰ０．５～１．０ｍｇ／Ｌ为宜。     

若尔盖地区25万年以来的植被与气候

本文根据ＲＭ孔上部６０ｍ２１０个样品的花粉分析结果,探讨了若尔盖地区２５万年以来的植被演替和气候变化。研究结果表明,若尔盖地区过去２５万年的植被演替和气候变化可划分为７个阶段。在约２５０－１９５ＫａＢ．Ｐ．（７阶段）,植被以亚高山莎草草甸为主,气温和降水与现在接近。在１９５－１２８ＫａＢ．Ｐ．（６阶段）和３２－１１ＫａＢ．Ｐ．（２阶段）,植被主要是荒漠草原,反映寒冷干旱的冰期气候,年平均气温比现在低５－６℃,年降水量仅为现在的６０－８０％左右。１２８－７１ＫａＢ．Ｐ．（５阶段）是过去２５万年中水热条件最好的时期,植被主要是亚高山暗针叶林和亚高山草甸,大部分时间的气温比现在高１℃左右,降水量稍高于现在;但在此阶段的气温和降水仍有较大的波动,５ｅ、５ｃ和５ａ阶段的气温和降水高于５ｂ和５ｄ阶段。７１－５８ＫａＢ．Ｐ．（４阶段）的植被主要是高山草甸为主,年平均气温比今低３－５℃,年降水量约为现在的８０％,在５８－３２ＫａＢ．Ｐ．（３阶段）,早期植被以亚高山暗针叶林和草甸为主,晚期主要是亚高山禾草草甸,气温和降水均明显高于４阶段,在晚期气温呈非线性逐渐下降的趋势。     

多孔菌液体发酵的研究

多孔菌Ｐｏｌｙｐｒｏｕｓｅｌｅｇａｎｓ（Ｂｕｌｌ）Ｆｒ。是一种新开发的真菌类中药材资源,经对其几个主要液体发酵培养条件的筛选研究,初步得出多孔菌深层发酵的基础参数：ＰＨ５．６～０．１;温度２４～２８℃;培养基为麦麸２．５％,蔗糖４％,ＮＨ４ＮＯ３０．０５％,ＫＨ：ＰＯ４０．０５％,ＭｇＳＯ４·７Ｈ２Ｏ０．０２５％。另外,摇瓶种子培养条件是：ＰＨ５．６～６．１;温度２８℃;培养基为ＰＤＡ＋ＶＢ１,添加３‰琼脂,时间为９６ｈｒ。     

丙型肝炎病毒基因组部份NS5区蛋白基因在大肠杆菌中的表达

在大肠杆菌中表达了丙型肝炎病毒基因组ＮＳ５区Ａ段和部份Ｂ段蛋白。ＮＳ５Ａ蛋白溶于水,可经过ＧＳＴ亲和层析柱纯化;ＮＳ５Ｂ蛋白不溶于水,经ＰＢＳ－Ｔｒｉｔｏｎ Ｘ－１００洗涤,尿素溶解后,通过离子交换柱纯化。经ＳＤＳ－ＰＡＧＥ和Ｗｅｓｔｅｍｂｌｏｔ分析,ＮＳ５Ａ蛋白除在５７ｋＤ左右有条带外,还有不同程度的降解产物;ＮＳ５Ｂ蛋白主要在５８ｋＤ左右有条带出现。为查明表达蛋白抗体在病人血清中的分布,取９     

哑特猕猴桃微繁工艺流程的研究

选用哑特猕猴桃腋芽为外植体。在不同发育阶段适宜培养基组成：芽增殖生长培养基为ＭＳ＋６－ＢＡ０．５ｍｇ／Ｌ＋ＩＡＡ０．１ｍｇ／Ｌ（或者ＩＢＡ０．１ｍｇ／Ｌ;ＮＡＡ０．１ｍｇ／Ｌ）,其在苗基部呈辐射状萌发多个嫩枝与主茎伸长生长同步进行的繁殖特点,有利提高繁殖率。４０ｄ繁殖系数为５－７。诱导生根培养基为ＭＳ＋ＩＢＡ０．５ｍｇ／Ｌ＋ＩＡＡ０．２ｍｇ／Ｌ,生根率达９７．１％,培养３０ｄ,平均苗高３．５ｃｍ,     

宫粉郁金的组织培养和快速繁殖

１植物名称宫粉郁金（Ｃｕｒｃｕｍａ　ｋｗａｎｇｓｉｅｎｓｉｓ）。２材料类别　块茎萌动芽。３培养条件　萌动芽生长培养基：（１）ＭＳ＋６－ＢＡ１ｍｇ·Ｌ－１（单位下同）＋ＮＡＡ０．２。不定芽增殖与愈伤组织诱导培养基：（２）ＭＳ＋６－ＢＡ１０＋ＫＴ５;（３）ＭＳ＋６．ＢＡ１０;（４）ＭＳ＋６－ＢＡ５＋ＫＴ２．５;（５）ＭＳ＋６－ＢＡ５;（６）ＭＳ＋６－ＢＡ２＋ＫＴ１。生根培养基：（７）ＭＳ＋ＮＡＡ０．５;（８）ＭＳ＋６－ＢＡ０．５＋ＮＡＡ０．５;（９）ＭＳ。以上培养基均加０．７％琼脂,３％蔗糖,ｐＨ５…     

小鼠B淋巴细胞活化过程中Ly—5（B220）的表达

本文通过ＦＡＣＳ技术,利用单克隆抗体ＲＡ３－６Ｂ２抗Ｌｙ－５（Ｂ２２０）研究了Ｌｙ－５（Ｂ２２０）在新制备的小鼠脾脏Ｂ细胞上的表达,特别是用不同的丝裂原刺激而激活Ｂ细胞后Ｌｙ－５（Ｌｙ－５ｈｉ）,浮力密度较低的大Ｂ细胞则为Ｌｙ－５＾ｌｏｗ。用多允隆刺激因子ＬＰＳ（细菌脂多糖）刺激脾脏高浮力密度小Ｂ细胞,可诱导Ｌｙ－５的表达仍保持较高状态,但当用抗－ＩｇＭ与白细胞介素－６一起刺激时,则诱导Ｌｙ－５的     

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).     

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.