TDZ：一种有效的植物生长调节剂

人工合成的苯基脲衍生物TDZ（N-苯基-N′-1,2,3-噻二唑-5-脲）是已被广泛用于植 物组织培养形态发生的高效生物调节剂。它能诱导外植体从愈伤组织形成到体细胞胚胎发生 的一系列不同反应,具有生长素和细胞分裂素双重作用的特殊功能。近年来通过研究TDZ启 动的形态发生事件,人们正逐渐揭示出其内在作用机理。许多研究报告指出TDZ通过调节内 源植物生长激素起作用,或者是诱导逆境产生起间接作用。它还能调节细胞膜结构、能量水 平、营养吸收和同化作用。本文将探讨TDZ几种可能的作用机理,并概述近年来有关TDZ诱导的植物离体形态发生效应研究进展。     

TDZ研究进展(综述)

TDZ在组培中应用广泛,植物中许多生理生化现象受TDZ影响。近年来研究初步表明,TDZ是通过调节内源激素起作用,或是诱导胁迫的结果。本文综述TDZ作用机理的研究进展。     

三种植物生长调节剂对密叶绢藓（Entodon challengeri）孢子萌发、原丝体发育及芽体发生的影响

研究了3种植物生长调节剂苯基噻二唑基脲(TDZ)、6-苄基腺嘌呤(6-BA)、萘乙酸(NAA)对密叶绢藓[Entodon challengeri(Paris)Cardot]孢子萌发、原丝体发育及芽体发生的影响,并对整个发育过程进行了显微观察和照相,结果表明:(1)3种植物生长调节剂对密叶绢藓孢子萌发影响不显著;(2)在原丝体发育阶段,1.0 mg/LNAA对原丝体初期的发育促进效果显著,0.4 mg/L TDZ对原丝体发育中期分枝的形成促进效果显著,6-BA处理效果不显著;(3)3种植物生长调节剂单独处理均促进芽体的发生,但0.4 mg/L TDZ效果最佳。而1.5 mg/L 6-BA TDZ组合处理效果更加显著;(4)芽体的发生数量与芽体的长势无正相关性。     

胁迫诱导植物体细胞胚发生中相关基因及蛋白的研究进展

植物体细胞胚发生是一个复杂的发育过程,体细胞胚发生已成为研究植物胚胎发育过程中生理、生化、分子生物学等方面分子机理的模式系统。胁迫被认为是对体细胞胚的诱导有重要作用的因素。植物生长调节物质如2,4-D、ABA等目前认为是与胚性能力获得有关的胁迫物质。在蛋白和转录水平上对基因表达的分析中已鉴定出一些与体细胞胚发生相关的基因和蛋白。该文主要对近年来国内外有关胁迫诱导体细胞胚发生的相关基因及蛋白的研究进展进行综述。     

三种植物生长调节剂对密叶绢藓(Entodon challengeri)孢子萌发、原丝体发育及芽体发生的影响

研究了3种植物生长调节剂苯基噻二唑基脲(TDZ)、6-苄基腺嘌呤(6-BA)、萘乙酸(NAA)对密叶绢藓[Entodon challengeri(Paris)Cardot]孢子萌发、原丝体发育及芽体发生的影响,并对整个发育过程进行了显微观察和照相,结果表明:(1)3种植物生长调节剂对密叶绢藓孢子萌发影响不显著;(2)在原丝体发育阶段,1.0 mg/LNAA对原丝体初期的发育促进效果显著,0.4 mg/L TDZ对原丝体发育中期分枝的形成促进效果显著,6-BA处理效果不显著;(3)3种植物生长调节剂单独处理均促进芽体的发生,但0.4 mg/L TDZ效果最佳。而1.5 mg/L 6-BA+TDZ组合处理效果更加显著;(4)芽体的发生数量与芽体的长势无正相关性。     

TDZ对莴苣(Lactuca sativa L.)器官发生及乙烯形成的影响

为了研究TDZ在植物器官发生中的生理作用,用不同浓度的TDZ替代MS中的BA,发现仅用1／50BA浓度（0．1mg／L）的TDZ处理,已相当于用BA处理所得芽数,可见它具有很强的细胞分裂素活性;但是TDZ又能显著促进乙烯形成,较低浓度时抑制莴苣的器官发生,可能此时乙烯起着主导作用。     

甜高梁离体再生体系的建立和组织结构变化的观察

以甜高粱成熟种子为外植体,调节不同生长调节物质配比建立甜高梁离体再生体系。结果表明在MS＋2．5mg．L^-12,4．D＋0．3mg·L^-1KT培养基上愈伤组织的诱导率可达77．26％;比较不同浓度6-BA或TDZ与NAA配合诱导愈伤组织分化和苗形成的情况,TDZ的作用优于6-BA。观察培养组织的结构变化发现,甜高粱离体再生过程中除了体细胞胚发生途径之外,还伴随有器官发生途径。     

植物开花逆转研究进展

介绍了植物开花逆转的概念、类型、发生条件,综述了在形态发生、生理、分子生物学等方面的研究进展,探讨了将开花逆转应用于植物发育生物学研究的可能性。作者提出,采用“诱导—非诱导—逆转”三位一体的实验系统,可提高植物光周期反应研究试验结果的可靠性,特别是可以提高在研究开花机理时的基因表达时空性方面的可靠性。     

细胞薄层培养在植物激素调节形态发生研究中的应用

从外源激素对形态发生的调节、植物激素的作用机制、形态发生的内源激素动态等方面概述了细胞薄层培养在植物激素诱导与调节形态发生研究中的应用进展,并对其在植物信号转导、玻璃化现象的发生机制、离体再生障碍的克服等研究领域的发展前景和尚存在的问题作了讨论。     

几种影响N-甲基-N-亚硝基脲诱导向日葵叶绿体基因突变的生理因素

用诱变剂N 甲基 N 亚硝基脲 (NMU)诱变向日葵种子时 ,温度、2 ,4 二硝基苯酚 (DNF)、利福平 (R)、KT、硝酸铵(AA)、二氨基苯甲酸 (DABA)和处理时间都会影响NMU对向日葵叶绿体的突变诱导效果。突变诱导的最佳温度为 15℃ ,2 ,4 二硝基苯酚、利福平、硝酸铵和二氨基苯甲酸明显降低花叶植株的频率 ,而KT则增加叶绿体突变的频率 ,在 0 .0 15 %KT作用下 ,叶绿体突变频率由 (8.5± 2 .9) %提高到 (2 5 .0± 4 .2 ) %。咖啡因 (COF)对诱导叶绿体突变没有任何作用。     

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.