高效液相色谱法测定大麦虫磷脂酰胆碱含量

建立高效液相色谱法测定大麦虫体内磷脂酰胆碱含量的方法。样品经甲醇提取、净化后,经高效液相色谱分析。采用外标法定量,磷脂酸胆碱标准溶液质量浓度在250～2 000 μg/mL范围内呈良好的线性相关,相关系数为0.999 6,样品加标回收率在97%～109%之间,相对标准偏差小于2.4%。对不同生长阶段大麦虫体内磷脂酰胆碱含量测定结果表明,大麦虫体内卵磷脂含量随个体重量的变化符合二项式曲线的变化规律,相关系数R2=0.865(P＜0.01)。     

乳腺癌转移中的磷脂酰胆碱和溶血磷脂酰胆碱分析

我们以前曾报道花生四烯酸（arachidonic acid,AA)代谢产物可以促进乳腺癌细胞增殖和迁移。为了进一步寻找维持高转移乳腺癌细胞中AA高水平代谢的内源机制,深入探求AA代谢促进乳腺癌细胞转移的分子机理,我们应用HPLC/ESI/MSⁿ技术检测和分析了乳腺癌MCF-7和高转移乳腺癌LM-MCF-7细胞中溶血磷脂酰胆碱（lysophosphatidylcholines,LysoPCs）和磷脂酰胆碱（phosphatidylcholines,PCs）的成分和含量。我们发现了10种LysoPC的含量在LM-MCF-7细胞中显著高于MCF-7细胞,有6种PC可水解产生AA,它们在LM-MCF-7细胞中的含量显著低于MCF-7细胞,提示这些溶血磷脂含量的升高和磷脂含量的降低可能与乳腺癌转移相关。在LM-MCF-7细胞中,COX-2抑制剂吲哚美辛（indomethacin,Indo）和LOX抑制剂（nordihydroguaiaretic acid,NDGA）共同作用可明显下调cPLA2的活性,应用HPLC-ESI-MSⁿ技术比较cPLA2活性下调前后LM-MCF-7细胞中LysoPC和PC含量的变化,发现其中4种PC可被cPLA2水解产生AA。我们还发现,细胞内LysoPC与PC的比值可以反映cPLA2的活性。通过以上研究我们进一步证实了由cPLA2活性调节的AA释放及代谢对乳腺癌转移具有重要作用。     

磷脂酰肌醇转移蛋白

磷脂酰肌醇转移蛋白(phosphatidylinositol/phosphatidylcholine transfer proteins,PITP)普遍存在于真核生物细胞中,PITP能够结合并交换一分子的磷脂酰肌醇(phosphatidylinositol,PI)或磷脂酰胆碱(phosphatidylcholine,PC),并促进这两类脂分子在细胞内膜组分间的转移。PITP对细胞内膜组分间脂类的运输和代谢、分泌囊泡的形成和运输、磷脂酶C(phospholipase,PLC)调节的信号传导以及神经退化等生理生化过程具有重要的影响。综述了近年来PITP的研究进展,并对目前研究中存在的一些问题进行探讨。     

土壤假单胞菌593使用Pcs途径合成磷酯酰胆碱

【目的】原核生物有两条代谢途径N-甲基化途径(Pmt途径)和磷脂酰胆碱合酶途径(Pcs途径)合成磷脂酰胆碱(PC)。本文对土壤细菌Pseudomonas sp.593的磷脂酰胆碱合成进行了研究,试图弄清楚假单胞菌的磷脂酰胆碱的合成途径。【方法】通过氨基酸序列比较,获得已报道的磷脂酰胆碱合酶(Pcs)的氨基酸保守序列,并设计简并引物,从Pseudomonas sp.593总DNA中PCR扩增出磷脂酰胆碱合酶基因(pcs)的片段,然后用扩增的DNA片段作探针,对Pseudomonas sp.593基因组DNA亚克隆文库进行菌落原位杂交,获得pcs全基因序列;利用同源重组原理进行活体突变,获得Pseudomonas sp.593 pcs-突变体;采用薄层层析(TLC)法分析细菌总磷脂,检测PC含量以及pcs基因活性。【结果】TLC分析显示Pseudomonas sp.593细菌仅在添加外源胆碱的M9或LB培养基中生长时才合成PC;从Pseudomonas sp.593细菌中克隆出894 bp的DNA序列,编码的蛋白具有磷脂酰胆碱合酶活性;活体缺失pcs基因后,Pseudomonas sp.593 pcs-突变体在添加或不添加胆碱的条件下都不能合成PC。【结论】Pcs途径是土壤Pseudomonas sp.593乃至其它假单胞菌合成磷脂酰胆碱的唯一途径。     

磷脂酰胆碱特异性磷脂酶C的研究

随着人们对信号转导认识的逐步加深,各种磷脂酶在信号通路中的作用也日渐受到重视,并日趋明了。其中磷脂酶Ａ２（ＰＬＡ２）、磷脂酰胆碱特异性磷脂酶Ｄ（ＰＣ－ＰＬＤ）的基因已克隆,对磷脂酰肌醇特异性磷脂酶Ｃ（ＰＩ－ＰＬＣ）也有较深了解,而对磷脂酰胆碱特异性磷...     

胆碱摄取及磷酯酰胆碱合成的调节研究

本文研究了多种氨基酸、乙醇胺和甲基醇胺对细胞摄取胆碱和合成磷脂酰胆碱的影响,发现多种氨基酸非竞争性抑制细胞摄取胆碱。含胆碱代谢物的分析显示胆碱转变成ＣＤＰ－胆碱,随之形成ＰＣ均不受氨基酸影响。乙醇胺竞争性的抑制胆碱摄取,且存在剂量依赖关系。乙醇胺能明显抑制胆碱激酶活,但细胞内胆碱和磷酸胆碱的代谢池并不改变,提示乙醇胺不影响胆碱转变成磷酸胆碱,根据ＣＤＰ－胆碱和ＰＣ的比放射性分布,乙醇胺也不影响ＰＣ     

胆固醇对二棕榈酰磷脂酰胆碱（DPPC）多层膜结构的影响

用小角Ｘ射线衍射（ＳＡＸＤ）和差示扫描量热（ＤＳＣ）方法研究胆固醇对二棕榈酸磷脂酰胆碱多层膜结构的影响。在不同胆因醇浓度及不同温度下的衍射实验和热吸收曲线实验显示纯磷脂的尖锐的凝胶－液晶相变随胆固醇含量增加而逐渐消失。当胆固醇含量约为４０（ｍｏｌ）％或更多时,衍射曲线和热吸收曲线均显示存在分相现象。     

磷脂酰胆碱对酒精性肝病保护作用的研究进展

酒精性肝病已逐渐成为第二大肝脏疾病,威胁着人类的健康。乙醇引发肝损伤的机制主要包括其代谢产物乙醛对肝细胞造成的毒性作用、自由基损伤及对肝脏线粒体产生的毒性作用等。已证实,磷脂酰胆碱对酒精肝损伤具有明显的保护作用。简要介绍了酒精肝病机制及磷脂酰胆碱对酒精性肝损伤的保护作用研究进展,以期为治疗酒精性肝病提供帮助。     

荧光光谱法研究铈离子与二棕榈酰磷脂酰胆碱（DPPC）脂质体的相互作用

通过荧光光谱法研究了稀土Ｃｅ＾３＋与二棕榈酰磷脂酰胆碱（ＤＰＰＣ）脂质体的相互作用,结果表明,Ｃｅ＾３＋－ＤＰＰＣ体系的激发波长在２４７ｎｍ,２９４ｎｍ,发射波长在３４４ｎｍ,与水合Ｃｅ＾３＋的荧光光谱完全不同。这表明Ｃｅ＾３＋与ＤＰＰＣ形成了复合物,该复合物的荧光光谱同Ｃｅ＾３＋－ＤＨＰ复合物的荧光光谱一致,可以认为Ｃｅ＾３＋与ＤＰＰＣ分子上的磷酸基团相作用。     

活体内磷脂酰胆碱替代磷脂酰乙醇胺影响E.coli细胞的功能

【目的】通过磷脂酰胆碱(PC)阳性大肠杆菌菌株与磷脂酰乙醇胺(PE)阳性野生型和PE阴性突变型菌株比较,并用PC+PE+双阳性菌株佐证,从细菌形态、生理生化以及巨噬细胞对细菌的吞噬作用等方面探讨活体内磷脂酰胆碱能否替代磷脂酰乙醇胺。【方法】光学和电子显微镜观察细菌形态和结构;不同条件培养细菌并使用分光光度计测定OD600值,评估细菌的生长情况;使用SDS-PAGE和2-D电泳法测定细菌间质蛋白组分;用小鼠RAW264.7巨噬细胞系检测细菌的粘附和吞噬作用。【结果】与短棒状的PE+野生型细菌AD93/pDD72相比,PC+细菌AD93/ptac67中仍有25%丝状体;与PE-突变体AD93一样,PC+细菌AD93/ptac67仍需要添加二价离子Mg2+或Ca2+才能生长;与野生型AD93/pDD72相比,PC+细菌AD93/ptac67的周质蛋白组分、粘附率与相对吞噬效率呈现明显的差异;与野生型细菌Top10/ptac85相比,PE+PC+双阳性细菌Top10/ptac66的细胞壁外层、抗逆性和周质蛋白组分也显示差别。【结论】在活体内,膜磷脂中PC替代PE不能使PE-突变体细胞的功能完全恢复至野生型状态,PE和PC在功能上存在明显的差别,两者在功能上不能相互替代。     

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.