植物苯丙氨酸解氨酶的研究——Ⅴ.PAL活性与尾穗苋黄化苗中苋红素积累的相关性

用不同因素诱导与抑制的方法较系统地探讨了尾穗苋黄化苗PAL活性与苋红素积累之间的关系。根据激动素诱导的时间曲线表明。PAL活性高峰较早于苋红素积累高峰;PAL活性及苋红素积累都随激动素浓度上升而上升。 光对激动素诱导的PAL活性有增效作用,对苋红素积累也有同样的增效作用。不同光质(蓝、红)对PAL活性的诱导结果表明:蓝光大于红光,同时蓝光下苋红素积累也大于红光。 用环己亚胺、放线菌素D及反式肉桂酸等处理激动素诱导的材料时,发现在各种抑制条件下PAL活性受抑的同时,苋红素合成也受抑制,且随着抑制剂浓度增加受抑程度也增加,可见PAL活性与苋红素积累之间有密切关系。本文提出了PAL可能参与苋红素双氢吲哚部分合成的设想,这与目前一般认为多巴是双氢吲哚直接前体的观点不同。     

诱抗处理对甜瓜叶片防卫酶活性的影响

以黄河蜜幼苗为材料,分析了化学诱导物处理后甜瓜叶片中几丁质酶(CHI)、β-1,3葡聚糖酶(GLU)、苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)活性的变化.结果显示:经5种化学诱导物处理后,甜瓜叶片PAL活性快速增加,于处理后第6天出现活性高峰;苯丙噻二唑(BTH)、水杨酸(SA)、草酸(OAA)和硅酸钠(Na2SiO3)处理后GLU活性变化与PAL相似,PPO活性在测定期内持续升高;磷酸氢二钾(K2HPO4)处理对GLU和PPO活性无明显影响;SA处理后叶片CHI活性明显升高,其它诱导物处理对CHI活性无明显影响.结果表明,防卫酶(特别是GLU和PPO)活性表达增强是BTH、OAA、SA和Na2SiO3等诱导物处理系统诱导甜瓜幼苗白粉病抗性增强的重要生化机制.     

茉莉酸对棉花单宁含量和抗虫相关酶活性的诱导效应

以植物生长调节物茉莉酸(Jasmonic acid,JA)为诱导子,以常规棉为研究对象,探讨了外源茉莉酸对棉花幼苗单宁和蛋白酶抑制素以及其它抗虫相关酶活性诱导的浓度依赖性和持久性,讨论了棉花抗虫相关物质的抗虫效果.结果表明,0.01、0.1和1.0 mmol/L茉莉酸都能在2周内诱导棉花单宁和胰蛋白酶抑制素(Proteinase inhibitors,PIs)含量增加,诱导多酚氧化酶(Polyphenol oxidase,PPO)、苯丙氨酸解氨酶(Phenylalanine ammonia-lyase,PAL)、过氧化物酶(Peroxidase,POD)和过氧化氢酶(Catalase,CAT)活性升高.对3种浓度茉莉酸的诱导效应进行分析表明,0.1 mmol/L茉莉酸对于诱导PIs、PPO、POD和CAT最有效,0.1和1.0 mmol/L茉莉酸对于诱导棉花单宁和苯丙氨酸解氨酶等效,二者的诱导效应均高于0.01 mmol/L.对茉莉酸诱导抗性的持久性进行分析表明,最佳诱导效应发生的时间各不相同:POD活性在JA处理后第1天最高,随后呈下降趋势,PIs和单宁含量分别在JA处理后第7天和第14天达最大值;JA处理后第1天和第7天的PPO活性无明显差异,但明显高于第14天;JA处理后第7天和第14天的PAL活性无明显差异,但明显高于第1天;JA处理后第1、7和14天棉花叶片的CAT活性均无明显差异.以上结果表明,茉莉酸可通过增加棉叶单宁和PIs含量、提高棉叶PAL、PPO、POD和CAT活性等增强棉花幼苗的抗虫性.     

新型光敏剂分子二乙醇胺基竹红菌乙素光诱导HeLa细胞死亡中的氧化应激研究

二乙醇胺基竹红菌乙素(2-ethanolamino-2-demethoxy-17-ethanolimino-hypocrellin B,EAHB)是一种新型的可吸收600 nm以上红光的竹红菌乙素衍生物。本文研究了二乙醇胺基竹红菌乙素-光动力诱导HeLa细胞死亡的效果及其氧化应激机制。结果发现,红光诱导后,MTT法检测到二乙醇胺基竹红菌乙素-光动力作用使HeLa细胞的存活率显著降低,且存活率与光敏剂浓度和光照剂量成反比;二乙醇胺基竹红菌乙素-光动力诱导HeLa细胞内产生活性氧自由基;同时,胞内超氧化物歧化酶和还原型谷胱甘肽水平显著降低,细胞脂质过氧化标志分子丙二醛显著升高,并检测到细胞质膜损伤标志分子乳酸脱氢酶的渗出显著增加。研究结果说明新型光敏剂二乙醇胺基竹红菌乙素可有效光诱导肿瘤细胞死亡,而细胞内氧化应激反应可能是二乙醇胺基竹红菌乙素光诱导肿瘤细胞死亡的重要作用机制。     

高温胁迫对厚壳贻贝摄食、代谢和相关酶活性的影响

为了探讨高温胁迫对厚壳贻贝生理代谢和免疫功能的影响,测定了不同温度胁迫水平(20→25℃; 20→30℃)下厚壳贻贝的滤水率、耗氧率、排氨率以及不同组织己糖激酶(HK)、丙酮酸激酶(PK)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)和超氧化物歧化酶(SOD)的活性。结果表明:25℃胁迫3 h后厚壳贻贝滤水率升高至0.56 L·g-1·h-1,但与对照组相比无显著变化,30℃处理后滤水率则显著降低;高温胁迫处理后,厚壳贻贝的耗氧率与排氨率均显著升高,25℃与30℃处理组间耗氧率无显著差异,但30℃处理组排氨率显著低于25℃;与对照组相比,外套膜和鳃HK活性无显著变化,但肝胰腺HK活性显著降低,鳃部HK活性显著高于外套膜和肝胰腺;外套膜PK活性显著升高,在30℃达到最大值,而25℃胁迫处理组鳃PK活性却显著降低;高温胁迫后外套膜ACP活性显著降低,25℃处理组肝胰腺ACP活性显著降低,但各处理组间鳃ACP活性无显著差异; 25℃下外套膜AKP活性显著升高,30℃时鳃和肝胰腺AKP活性显著低于对照组; 30℃胁迫下外套膜SOD活性显著升高,鳃和肝胰腺SOD活性无显著变化,肝胰腺SOD活性显著低于鳃和外套膜。实验表明,一定温度变化范围内,厚壳贻贝可通过调节自身代谢水平应对温度升高带来的胁迫,但短时间内大幅升温显著影响厚壳贻贝的摄食、代谢和免疫反应。厚壳贻贝代谢酶和免疫酶活性具有组织特异性。     

红厚壳茎段丛生芽诱导与植株再生北大核心CSCD

红厚壳(Calophyllum inophyllum)为藤黄科红厚壳属多年生木本植物,有很高的药用价值。该研究以红厚壳带节茎段为外植体,探讨生长调节剂对腋芽萌发及丛生芽诱导、伸长和试管苗生根的影响。研究结果表明,外植体腋芽萌发和丛生芽诱导效果最好的培养基是MS+NAA1.0+TDZ0.5,在此条件下培养21天后,转入添加0.5 g·L–1活性炭且无生长调节剂的MS培养基,可有效促进不定芽的伸长。将带不定芽的外植体先在附加1.0 mg·L–1NAA的1/2MS培养基上进行生根诱导4周,之后转入附加1.0 g·L–1活性炭的无激素培养基进行根的伸长培养,这样的两步生根法能有效促进红厚壳生根。     

红厚壳茎段丛生芽诱导与植株再生

红厚壳(Calophyllum inophyllum)为藤黄科红厚壳属多年生木本植物,有很高的药用价值。该研究以红厚壳带节茎段为外植体,探讨生长调节剂对腋芽萌发及丛生芽诱导、伸长和试管苗生根的影响。研究结果表明,外植体腋芽萌发和丛生芽诱导效果最好的培养基是MS+NAA1.0+TDZ0.5,在此条件下培养21天后,转入添加0.5 g·L–1活性炭且无生长调节剂的MS培养基,可有效促进不定芽的伸长。将带不定芽的外植体先在附加1.0 mg·L–1NAA的1/2MS培养基上进行生根诱导4周,之后转入附加1.0 g·L–1活性炭的无激素培养基进行根的伸长培养,这样的两步生根法能有效促进红厚壳生根。     

Chib1和PAL5基因在AM真菌Glomus fasciculatus诱导大豆抗线虫病害防御反应中的作用

本研究系统分析了大豆（品种：‘鲁豆4’）接种AM真菌Glomus fasciculatum和胞囊线虫（SCN,Heterodera glycines）4号生理小种后各处理菌根和线虫侵染率、几丁质酶和苯丙氨酸解氨酶（PAL）活性及几丁质酶基因Chib1和苯丙氨酸解氨酶基因PAL5转录物的动态变化。结果表明,接种SCN对AM真菌的侵染率没有产生显著影响,但先接种AM真菌后接种SCN的大豆根内线虫侵染率明显低于只接种SCN的处理。另外,先接种AM真菌后接种SCN的大豆根内几丁质酶和PAL活性显著提高,活性高峰出现在接种线虫后的第3天。值得注意的是,先接种AM真菌后接种SCN的大豆根内两种基因Chib1和PAL5转录物高峰也出现在接种SCN后的第3天,即AM真菌侵染率快速上升而SCN侵染率快速下降时期。所以Chib1和PAL5基因的表达可能是AM真菌诱导的抗大豆胞囊线虫病害防御反应的一种表现。因此推测Chib1和PAL5直接参与了AM真菌诱导大豆抗胞囊线虫病害的防御反应。     

质膜NADPH氧化酶的活化与H2O2的产生介导内源激发子诱导人参悬浮细胞中PAL活性的提高与人参皂甙的积累

利用纤维素酶降解人参(Panax ginseng C.A.Meyer)悬浮细胞的细胞壁制备了内源激发子(CDW).CDW体外诱导了游离人参细胞质膜NADPH氧化酶的活性,激发了活体人参悬浮细胞产生H2O2.CDW还可以诱导提高苯丙氨酸解氨酶(PAL)活性,促进人参鲨烯环氧酶基因(sqe)的转录与人参皂甙的积累.NADPH氧化酶的抑制剂不仅可以抑制CDW体外诱导的质膜NADPH活性而且还可以抑制CDW诱导人参细胞产生H2O2.进而,这些抑制剂还可以抑制CDW诱导PAL活性的提高,以及sqe的转录与人参皂甙的合成.过氧化氢酶与H2O2的粹灭剂也可以抑制CDW激发产生的这些诱导效应.上述结果表明CDW激发质膜NADPH氧化酶的活化与H2O2的产生在介导CDW诱导人参细胞抗性反应中,包括PAL活性的提高与人参皂甙的积累,起了重要的信号转导作用.     

热带滨海植物红厚壳的抗逆生物学特性

为了解红厚壳(Calophyllum inophyllum)的抗逆特性,对西沙群岛自然生长的红厚壳叶片的形态解剖、生理生态、以及叶片和适生土壤的元素含量进行了研究。结果表明,红厚壳是阳生性植物,其上表皮厚,海绵组织发达且栅栏组织排列紧密,气孔排列松散且密度小(24.40 mm~(-2)),有利于叶片保水抵御干旱。叶片的叶绿素a、b含量低(分别为0.87和0.43 mg g~(-1)),表明红厚壳具适应强光环境的能力。叶片的MDA含量低(13.46 nmol g~(-1)),PRO含量高(127.89μg g~(-1)),SOD活性高(149.42 U g~(-1)),总抗氧化能力高(388.60 U g~(-1)),显示红厚壳能通过提高自身的抗氧化能力抵御膜脂过氧化伤害。红厚壳自然生长的珊瑚岛土壤较为贫瘠、营养元素含量低,但红厚壳植株体内具有较高的营养元素含量,表明红厚壳营养元素利用率高,对于贫瘠土壤具有很好的适应能力。因此,红厚壳具有较高的抗氧化胁迫能力和耐受干旱的能力,适宜生长在热带珊瑚岛等土壤贫瘠的生境,可以作为热带珊瑚岛防风固沙和植被恢复的工具种。     

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.