大肠杆菌感受态细胞培养与冻存条件的研究

测定大肠杆菌JM107在37℃培养条件下的生长曲线,制备其对数生长期不同阶段感受态冻存细胞,并对冻存细胞的转化率进行研究。结果显示：分离良好的单个新鲜菌落接种于50mlSOB培养基,经37℃,170～180r/min振荡培养210min左右,所得冻存细胞转化率最高,－7O℃保存时可达5．2×10⁷转化子／μgDNA且感受态保持时间长,即使存放两个月仍能保持相当高的转化率。－20℃保存时也能在三周内保持较高转化率。     

原生质体来源的大白菜悬浮细胞系的超低温保存

原生质体来源的大白菜 Brasstca campessris var.pekinsis 悬浮细胞系在二甲亚砜的保护下,能在液氮中(-196℃)长期冻存。加入山梨醇能增强保护作用;而加入甘露糖则降低保护作用。培养基对冻存也有明显的影响。在液氮中存放的时间长短对细胞存活率没有多大影响。冻后相对活性最高可达75.4％,恢复生长快,化冻后重新悬浮培养6天,生长量可达300-500％。遮光比不遮光对恢复更有利。冻存后恢复生长的悬浮细胞,能与未经冰冻的对照一样进行原生质体分离和培养。     

最小体积玻璃化冻存技术在生物医学领域的进展和应用

细胞和组织的生物保存在辅助生殖医学、再生医学和器官移植等领域均具有至关重要的作用,对公共健康具有广泛影响.生物保存方法主要包括传统的程序化慢冻法(slow freezing)和玻璃化冻存技术(vitrification).玻璃化冻存技术可通过降低或避免结晶的产生而显著提高细胞解冻后的活性和功能.但玻璃化冻存技术通常采用较高浓度的冷冻保护剂(cryoprotectant agent, CPA),会对细胞和组织产生一定的毒性和渗透压力.研究显示,通过减小玻璃化冻存中样品的体积(1μL)可显著提高冷却速率,从而降低玻璃化冻存所需的CPA浓度.而微纳技术的迅速发展使得皮升至纳升量级样本的操作成为可能.因此,微纳技术与低温学的有机结合将为未来生物保存技术的发展提供巨大的潜能.     

美洲鲥雄性生殖细胞冷冻保存及移植

采用分离细胞冻存和组织块直接冻存2种方法, 进行美洲鲥(American shad, Alosa sapidissima)精巢细胞的长时间冷冻保存(>250d), 并比较分析2种不同冻存方法对美洲鲥雄性生殖细胞的冻存效果。解冻复苏后用Hochest33342和PI共染细胞核, 分析统计各期雄性生殖细胞的存活率, 结果显示组织块冻存方法所得精原干细胞和精母细胞的存活率明显高于分离细胞冻存的; 而精细胞及其他细胞存活率在2种方法间无显著差异; 特别是, 镜检发现组织块冻存方法所得精子存活率高达93.83%, 说明此冻存方法能同时高效地冻存美洲鲥各期生殖细胞, 包括成熟的精子。同时, 将组织块冻存的美洲鲥生殖细胞用PKH26染色标记后移植到出苗第1天的斑马鱼仔鱼中, 在细胞植入后5d仍能在受体中检测到供体细胞, 且有部分供体细胞能与内源生殖细胞共定位, 表明经过长时间冷冻保存的美洲鲥生殖细胞仍具有生殖细胞特性, 且能整合到斑马鱼受体性腺原基。研究结果为进一步开展美洲鲥, 或其他洄游性鱼类的生殖细胞发育、培养及种质资源保存等研究工作奠定了技术理论基础。     

恒河猴(Macaca mulatta)肾细胞冻存复苏培养及其生物学特性的研究

本文使用深低温(-196℃)冻结保存动物细胞技术,对胰酶分散的恒河猴肾细胞的冻存,复苏培养及其生物学特性进行了研究。结果表明、液氮冻存2—58周的恒河猴肾细胞,其平均存活率为63.3—74.4％。复苏培养细胞于6—7天形成緻密单层,对脊髓灰质炎病毒敏感;国产二甲基亚砜可以用作冻存细胞的保护剂;复苏培养的细胞核型正常;其生物学特性与未冻的原代细胞一致。     

光镊捕获的单个解冻人血红细胞的拉曼光谱研究

红细胞的冰冻与解冻的实施为血液的长期保存提供了有效的方法。在过去的几十年中,红细胞冻存有过数种方法,其中高甘油冻存法比较普遍,因而用此方法保存红细胞是否对红细胞产生了影响及产生了什么影响是值得研究的。作者利用激光光镊拉曼光谱系统,通过拉曼光谱对冻存人血红细胞进行研究;结果显示,红细胞冻存前后的拉曼光谱有一定的变化,解冻提取后也产生了一定的变化,这些变化主要体现在对应拉曼光谱的位置和强度上。研究结果对进一步研究红细胞的冻存具有一定的参考价值。     

低浓度二甲基亚砜保护SSMC7721细胞冻存后活力

目的研究二甲基亚砜作为冻存保护剂对SSMC7721细胞冻存复苏后细胞生长相对活力和凋亡的影响。方法选择传代培养处于对数生长期SSMC7721细胞,体积分数2%、5%、10%和20%DMSO分别冻存10d、30d后复苏,采用倒置显微镜形态学观察、MTT法测定细胞相对活力、流式细胞仪检测细胞凋亡,综合分析不同浓度DMSO冻存不同时间复苏对SSMC7721的影响。结果各浓度DMSO冻存SSMC7721对细胞生长和凋亡均有影响。20%DMSO对SSMC7721细胞影响明显,细胞培养不易贴壁逐渐脱落,浓度低于5%时,细胞生长状态良好;10%和20%DMSO细胞相对活力急剧下降;随着DMSO浓度增加和冻存时间延长,细胞凋亡率明显上升,存活率明显下降,5%DMSO冻存的凋亡率10.24%,20%DMSO冻存的凋亡率93.49%。结论 2%~5%DMSO冻存肝癌SSMC7721细胞,复苏后培养有较好的细胞相对活力,能有效减少细胞凋亡,起到的冻存保护剂作用。     

谷胱甘肽与富氢冻存液在鸡血细胞冻存中的保护作用

目的通过观察细胞冷冻复苏后的存活率及凋亡情况,探讨细胞冻存液中添加谷胱甘肽(GSH)和氢气(H_2)对细胞的保护作用。方法在冻存液中添加GSH和/或通入H_2后冻存鸡血细胞,1个月后复苏,采用台盼蓝拒染和MTT法分别检测细胞存活率与细胞活性,流式细胞仪检测细胞的凋亡率。结果 GSH、H_2或H_2+GSH处理使细胞活力明显提高,而早期凋亡率明显降低。结论谷胱甘肽与富氢冻存液对鸡血细胞冻存具有保护作用。     

人外周血淋巴细胞长期冻存后结构和功能的研究

从肝素和 ACD 抗凝血中分离的淋巴细胞,用 DMSO 或甘油作为低温保护剂,保存在液氮内,在冻前和冻后10、20、40和365天时分别检测细胞的功能活性。当冻存液内含10%DMSO 和40%人 AB 血清时,冻存效果最好。冻存一年时,淋巴细胞的回收率和存活率均大于92.5%。冻存细胞的 E 和 ME 花环形成率、ANAE 阳性率、LDH 同工酶谱和细胞超微结构与冻前相比,均无明显变化,冻存细胞的淋转能力虽在冻存初期有所下降,以后就处于稳定状态。     

乳猪肝细胞短期培养后的低温保存

本文对乳猪肝细胞短期培养后冻存法和直接冻存法进行比较。采用改良原位两步胶原酶灌注法分离乳猪肝细胞,将肝细胞接种到含10％DMSO、激素、生长因子和10％NBS的RPM1 1640培养基中,用阶段性冻存法保存肝细胞,分别对直接冻存和培养后冻存10天、20天复苏的肝细胞进行培养,动态观察其活率和功能。研究结果表明各组复苏后的肝细胞均保持较高的活率;短期培养后冻存组肝细胞活率、G-6-Pase活性、白蛋白和葡萄糖合成功能及安定转化能力均较直接冻存组为高;LDH活性低于直接冻存组;冻存时间的长短对其白蛋白、尿素和葡萄糖合成功能有一定影响。因此,短期培养后冻存法较直接冻存法为好。     

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.