山黧豆160年研究历程及进展

在全球范围内曾多次发生因过量食用山黧豆导致神经中毒事件,使得国内外对于山黧豆的种植和利用存在一定的误解和偏见,山黧豆的优良农艺价值和潜在功能食品利用价值也受到一定限制。但山黧豆适应性强、分布范围广,是全球气候变化条件下农业可持续发展和地力维持的优选作物,在食品安全、生态文明建设和乡村振兴新形势下,进一步研究和挖掘利用这一古老的优良作物具有重要的战略意义。山黧豆相关研究报道可追溯到1861年,距今已有160年的历史。在同行学者的不懈努力下,山黧豆基础研究及种质资源利用等方面均取得了显著的阶段性成果。该文系统回顾了山黧豆研究160年以来的发展历程,依托历史文献进行了梳理和分析。首先,基于山黧豆神经活性物质β ODAP的分离和鉴定、神经山黧豆中毒机制的探索、β ODAP生物合成途径解析等重要研究节点将整个山黧豆研究进程划分为山黧豆中毒因素的探索、神经山黧豆中毒机理解析和神经山黧豆中毒及β ODAP生物学功能的再认识等三个阶段。其次,总结了山黧豆在毒理学研究、种质资源利用、品质改良基础研究等方面取得的重要进展。特别是以兰州大学为代表的中国学者在β ODAP的分析检测、生物合成途径、山黧豆生理生态学研究及种质资源利用等方面进行了深入探讨,确立了中国在国际山黧豆研究中的主流地位。最后,针对目前山黧豆分子生物学基础研究相对滞后、种质资源缺乏系统利用等问题进行了展望,提出了未来的重点发展方向,为山黧豆种质资源的进一步深入挖掘和应用提供参考。     

山黧豆及其神经毒素(ODAP)的研究进展

山黧豆具有耐寒、耐旱等优良生产性状，且营养丰富，在恶劣的天气条件下仍能维持较高的产量，因此它是半干旱地区的潜在粮食作物。但长期食用山黧豆会引起中毒，这是由于山黧豆中含有的神经毒素（ＯＤＡＰ）所致，因此筛选无毒品系具有重要意义。本文对山黧豆神经毒素（ＯＤＡＰ）的生物合成毒素异构化等方面作简要综述。     

山黧豆毒素ODAP的生物合成及与抗逆性关系研究进展

有关山黧豆毒素ODAP的生物合成途径的前体物和合成程序已经证实,但其关键合成酶尚未分离与鉴定,因而无法克隆相应基因和利用反义RNA技术以控制其生物合成。研究表明,利用相应的抑制剂控制ODAP生物合成前体物可降低ODAP的积累量。山黧豆中ODAP含量与其抗逆性之间密切相关,这与其能有效地清除山黧豆中·OH自由基有关,外源ODAP处理获同样效果。此外,因ODAP既是含氮化合物,又是游离氨基酸,极易溶于水,可在逆境胁迫下与脯氨酸和多胺一样大量而迅速地积累,推测它也可能作为细胞渗透调节物质和防脱水剂,并在氮代谢和能量代谢方面起重要作用。对今后该领域的重点研究方向也进行了探讨。     

山黧豆毒素的薄层分离

通过对山黧豆中常见的20几种游离氨基酸薄层层析发现,其毒素ODAP的Rf值与好几种相关氨基酸的接近,而用阳离子交换柱对氨基酸抽提样进行简单的分离纯化,第一个洗脱出来的即为ODAP,这样在排除其它氨基酸干扰的情况下再进行ODAP的薄层分析将得到准确的结果。     

山黧豆神经性中毒机理的研究进展

山黧豆(Lathyrus sativas L.)是优良的旱地作物种质资源,但长期过量食用会导致人畜神经性山黧豆中毒(neurolathyrism)。山黧豆中毒是一种发生在人类和动物中的神经退行性疾病,在发展中国家(如印度、孟加拉国、巴基斯坦、尼泊尔、埃塞俄比亚和我国西北等地区)时有发生,但其细胞及分子机理尚不明确。研究山黧豆中毒的致病机理对防止山黧豆中毒和中毒后的有效治疗具有重要意义。已有的研究表明,β-N-草酰-L-α,β-二氨基丙酸(β-N-oxalyl-L-α,β-diaminopropionic acid,β-ODAP)为主要致病毒素,其可通过干扰谷氨酸的正常功能、破坏神经细胞内钙稳态、加剧氧化胁迫并破坏线粒体的功能等来诱发神经细胞损伤或死亡,阻断交感神经对肌肉的控制,最终导致人下肢或动物后肢肌肉萎缩和不可逆瘫痪。文章综述了近年来神经性山黧豆中毒的机制研究,对今后的研究提供参考和借鉴。     

水分胁迫下山黧豆多胺代谢与 β-N-草酰-L-α ,β-二氨基丙酸积累相关性的研究

为了研究水分胁迫下山黧豆 (LathyrussativusL .)叶片中多胺代谢与 β_N_草酰_L_α,β_二氨基丙酸 (ODAP)积累的相关关系 ,利用聚乙二醇 (PEG)对山黧豆幼苗进行水分胁迫处理 ,同时加入腐胺 (Put) ,α_二氟甲基精氨酸(DFMA)和Put DFMA。实验结果表明 ,随PEG处理时间的延长 ,山黧豆幼苗叶片中Put、亚精胺 (Spd)和精胺 (Spm)含量逐渐增加 ,特别是Spm含量增加显著 ,同时ODAP逐渐积累 ;在PEG处理的同时 ,加入Put使得Put、Spd含量显著增加 ,但对Spm影响不大 ,同样对ODAP含量影响也较小 ;加入DFMA可显著抑制Put、Spd、Spm的积累 ,同时也抑制了ODAP的积累 ;加入Put DFMA ,Put可以部分地减缓DFMA对两种内源多胺 (Put和Spd)合成的抑制作用 ,但对Spm所受DFMA的抑制作用影响不大 ,这时ODAP的积累也受到抑制。由此可见 ,水分胁迫对山黧豆幼苗叶片中多胺特别是Spm含量的增加与ODAP的积累密切相关。     

渗透胁迫对山黧豆幼苗H_2O_2及毒素积累的影响

用PEG经根部处理 15d龄的山黧豆幼苗 ,取幼苗叶片为实验材料 ,测定过氧化氢酶 (CAT)、过氧化物酶 (POD)活性、过氧化氢 (H2 O2 )和毒素 ( β N oxalyl α ,β diaminopropionicacid ,ODAP)的含量。结果表明 ,随着PEG处理时间的延长 ,POD和CAT活性降低 ,而H2 O2 和ODAP含量显著升高 ;在PEG处理液中加入二乙基二硫代氨基甲酸钠 (diethyldithiocarbamate ,DDC)和氨基三唑 (aminotriazole ,AT)后分别抑制和促进H2 O2 的产生 ,DDC可降低叶片中ODAP的含量 ,AT则使ODAP积累。由此我们推测 ,水分胁迫条件下活性氧代谢与ODAP的积累有关     

渗透胁迫对山黧豆幼苗H2O2及毒素积累的影响

用PEG经根部处理15d龄的山黧豆幼苗,取幼苗叶片为实验材料,测定过氧化氢酶（CAT）、过氧化物酶（POD）活性、过氧化氢（H2O2）和毒素（β-N-oxalyl-α,β-diaminopropionic acid,ODAP）的含量。结果表明,随着PEG处理时间的延长,POD和CAT活性降低,而H2O2和ODAP含量显著升高;在PEG处理液中加入二乙基二硫代氨基甲酸钠(diethyldithiocarbamate,DDC)和氨基三唑(aminotriazole,AT)后分别抑制和促进H2O2的产生,DDC可降低叶片中ODAP的含量,AT则使ODAP积累。由此我们推测,水分胁迫条件下活性氧代谢与ODAP的积累有关。     

山黧豆胚胎发育过程中ODAP和一些大分子物质含量的变化

应用微量分析方法检测了山黧豆胚胎发育过程中ODAP毒素含量和核酸、蛋白质、糖类等大分子物质的含量变化。结果表明:每粒种子的ODAP含量随着胚的发育而增加。每粒种子DNA量随着细胞的迅速分裂而增加,R、蛋白质、淀粉含量随着胚的发育而成倍地增加,当进入心形胚时这些物质的增加更为迅速。如以每克干重中的含量来表示,那么ODAP、DNA及可溶性糖含量则随胚的发育而下降,其它大分子物质含量在胚发育前期升高,进入心形胚时,这些物质达到最高峰;到鱼雷胚时,这些物质含量开始下降,直到胚基本分化完全时,降到最低点;只有酸性蛋白质含量一直保持增长。     

山黧豆毒素β-ODAP的生态学功能及应用

山黧豆是一种具有广谱抗逆性且营养丰富的豆科作物,但其含有β-N-草酰-L-α,β-二氨基丙氨酸(β-N-oxalyl-L-α,β-diaminopropionic acid, β-ODAP)神经毒素,人畜长期大量食用会导致神经性中毒,因此限制了山黧豆种质资源的利用.本文综述了干旱胁迫下山黧豆毒素β-ODAP对植株渗透调节和生长调节的影响,以及β-ODAP的分析方法、毒理机理和实用价值方面的研究进展,并对低毒和无毒品种选育策略进行了总结.干旱胁迫下,山黧豆合成大量毒素β-ODAP,其含量随胁迫程度增强而逐渐升高.β-ODAP可为植株生长和种子发育提供氮源,并积极参与清除活性氧过程,作为小分子可溶性氨基酸参与渗透调节,作为锌离子转运体参与根瘤发育.而含硫氨基酸(甲硫氨酸和半胱氨酸)含量升高可使山黧豆毒性显著降低.近年来,在山黧豆种质资源收集、杂交育种,以及通过组织培养和基因操作等技术进行低毒或无毒山黧豆品种选育方面做了大量工作.β-ODAP可通过破坏细胞内Ca²⁺稳态和作为谷氨酸类似物引发兴奋性中毒,但在止血和抗肿瘤等方面有重要的药用价值.     

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.