苍耳4种溶剂提取物除草活性的研究

以油菜(Brassica campestris L.)、黄瓜(Cucumis sativus L.)、小麦(Triticum aestivum L.)和高粱(Sorghum vulgare Pers.)4种作物种子为供试材料,用种子萌发法测定了苍耳(Xanthium sibiricum Patrin)全株的石油醚、乙酸乙酯、丙酮和苯4种溶剂提取物的除草活性。结果表明,苍耳丙酮提取物对4种作物生长的抑制活性最高,其次为乙酸乙酯提取物和苯提取物,石油醚提取物对4种作物生长的抑制活性最低。不同作物幼根和幼茎对4种溶剂提取物的敏感性不同,油菜和高粱的幼根对苍耳丙酮提取物极为敏感,5 g.L-1苍耳丙酮提取物对油菜和高粱幼根生长的抑制率分别为90.7%和92.1%。     

泥胡菜等8种草本植物提取物除草活性的生物测定

采用顺序提取法制备了泥胡菜（Hemistepta lyrata Bunge）等8种草本植物全草的石油醚、乙酸乙酯和乙醇提取物,并以高粱（Sorghum vulgare Pers．）、黄瓜（Cucumis sativus L．）、小麦（Triticum aestivum L．）和油菜（Brassica campestris L．）为供试对象,用种子萌发法对提取物的除草活性进行了生物测定。结果表明,所有提取物对4种作物幼苗根和茎的生长均有一定的抑制作用,但抑制率有一定差异。泥胡菜和獯草[Humulus scandens（Lour．）Merr．]的乙酸乙酯提取物对作物幼苗根和茎的抑制作用最强,抑制率随提取物浓度的提高逐渐增高,且对作物幼苗根生长的抑制强度高于茎。在低浓度（12．5g·L^-1）条件下,泥胡菜乙酸乙酯提取物对小麦幼苗根和茎生长的抑制作用最强;蓓草乙酸乙酯提取物对高粱幼苗根的生长及油菜幼苗根和茎的生长抑制作用最强。研究结果显示,泥胡菜及蓰草的乙酸乙酯提取物具有潜在的除草活性。     

20种植物提取物抑制植物病原菌活性研究

以小麦纹枯病菌(Rhizoctonia cerealis)、番茄灰霉病菌(Alternaria solani)这两种植物病原真菌为供试菌,对采自江西省吉安市的20种植物提取物的抑制菌丝生长活性及孢子萌发进行测定.结果表明,在供试质量浓度为1 mg/mL时,黄花草木樨乙醇提取物的乙酸乙酯萃取部分抑菌效果最好,对小麦纹枯病菌和番茄灰霉病菌两种菌的抑制率均达100%;窃衣、小白酒草、羊蹄和车前草的抑制作用次之,对两种菌的抑制率均大于80%;单从对一种病原菌的抑制作用看,还有黄荆对小麦纹枯病菌率为100%,空心莲子草、窃衣、小白酒草和鬼针草对番茄灰霉病菌的抑制率为100%,但是,这20种供试植物的石油醚相和水相萃取物对两种病原真菌的抑制效果均不强.抑制病原菌孢子萌发亦得到类似结果.以上结果提示植物抑菌活性成分主要存在于乙酸乙酯萃取部分,黄花草木樨、窃衣、小白酒草等的提取物作为植物源杀菌剂值得进一步研究.     

外来入侵植物小飞蓬化感物质的释放途径

在室内以滤纸为载体用离体生测方法测定了小飞蓬(Conyza canadesiL.)全株水浸提物、茎叶淋溶物、根系分泌物及残体土壤分解物对萝卜(Raphanussativus L.)、黄瓜(Cucumis sativus L.)、马唐(Digitarias anguinalis(L.)Scop.)油菜(Brassica campestris L.)和小麦(Triticuma estivum L.)的化感效应,同时在温室内以土壤为载体通过盆栽植物浇灌的方法测定了小飞蓬茎叶淋溶物和根系分泌物对盆栽植物生长的影响。室内生测实验结果表明,小飞蓬全株水浸提物对5种受体种子的萌发和幼苗生长均有较强的抑制作用;根系分泌物、茎叶淋溶物和残体土壤分解物对受体种子的生长抑制作用不同,根系分泌物的活性高于茎叶淋溶物和残体土壤分解物。温室盆栽实验结果也表明,小飞蓬根系分泌物对受体生长的影响高于茎叶淋溶物。这些结果说明根系分泌是小飞蓬化感物质释放的主要途径之一。     

小桐子提取物除草活性的生物测定

为全面了解小桐子(Jatropha curcas L. )提取物的除草活性,以萝卜(Raphanus sativus L. )、苋(Amaranthus tricolor L. )、苏丹草[Sorghum sudanense (Piper) Stapf]和黑麦草(Lolium perenne L. )为实验材料,对小桐子果壳和枝叶的水、乙醇(体积分数95%)、正丁醇、乙酸乙酯、氯仿和石油醚粗提物的除草活性进行了生物测定,并从中筛选出抑制作用最强的水粗提物进行进一步的活性组分分离及其除草活性的生物测定.测定结果显示,小桐子果壳和枝叶的6种溶剂提取物(10 g·L~(-1))对供试的4种植物幼苗的根长和茎高均有不同程度的抑制作用,其中水粗提物和乙醇(体积分数95%)粗提物的抑制作用较强,且水粗提物对供试的4种植物幼苗的根长和茎高的抑制作用均在75%以上,显著高于其他溶剂粗提物(P<0.05);石油醚粗提物的抑制作用最小,均在10%以下.小桐子果壳和枝叶水粗提物的石油醚、氯仿、乙酸乙酯、正丁醇和水萃取物(10 g·L~(-1))对萝卜和苏丹草幼苗的根长和茎高均有不同程度的抑制作用,其中水、正丁醇和乙酸乙酯萃取物的抑制作用显著高于氯仿和石油醚萃取物,抑制率均在70%以上;水萃取物的抑制作用最强,抑制率均在80%以上;石油醚萃取物的抑制作用最小,抑制率均在10%以下.研究结果表明,小桐子果壳和枝叶的水粗提物具有一定的除草活性,其有效成分为极性较大的组分.     

黄柏果实提取物对植物病原真菌的抑制作用

在室内测定了芸香科植物黄柏(Phellodendron chinese Schneid.)果实乙醇粗提物及其4个不同极性溶剂的萃取部分在浓度为1 mg/mL时对小麦纹枯病菌(Rhizoctonia cerealis)、稻纹枯病菌(Rhizoctonia solani)、番茄镰刀菌萎焉病菌(Fusarium oxysporum f. sp.lycopersici)、黄瓜枯萎病菌(Fusarium oxysporum f.sp.cucumerinum)、棉花枯萎病菌(Fusarium vasinfectum)、棉花黄萎病菌(Verticillium dahliae)、小麦赤霉病菌(Fusarium graminearum)、玉米小斑病菌(Bipolaris maydis)、西瓜枯萎病菌(Fusarium oxysporum f.sp.niverum)、梨黑星病菌(Venturia piri-na)、稻瘟病菌(Magnaporthe grisea)等11种植物病原真菌的抑制作用.乙酸乙酯部分和正丁醇部分对植物病原菌均表现出较强的抑制活性,其中乙酸乙酯部分对两种丝核菌小麦纹枯病菌和稻纹枯病菌的生长抑制作用最强,抑制率分别为100.00%和89.36%;正丁醇部分对两者的抑制率分别为97.32%和61.32%.实验结果表明,黄柏果实中的抗真菌活性成分主要存在于乙醇粗提物中的乙酸乙酯和正丁醇萃取部分中.     

龙柏枝叶水浸提液及其萃取物除草活性的生物测定

采用培养皿滤纸法,以油菜(Brassica campestris L. )、反枝苋(Amaranthus retroflexus L. )、生菜(Lactuca sativa L. var. ramosa Hort. )、番茄(Lycopersicon esculentum Miller)和小麦(Triticum aestivum L. )为供试植物,对龙柏(Sabina chinensis 'Kaizuca')枝叶水浸提液的除草活性进行了生物测定,并以番茄为测定对象,对水浸提液的不同溶剂萃取物的除草活性也进行了生物测定;另外,采用薄层层析法对乙酸乙酯萃取物的除草活性成分进行了初步定性分析.结果显示,在0.05～0.2 g·mL-1质量浓度范围内,龙柏枝叶水浸提液对5种植物的种子萌发及幼苗根长和茎高均有一定的抑制作用,且随质量浓度的提高,抑制作用逐渐增强,其中0.2 g·mL-1水浸提液对5种植物的种子萌发及幼苗根长和茎高的抑制率均在80.00%以上, 对番茄种子萌发及幼苗根长和茎高的抑制率最高, 均达到100.00%.在龙柏枝叶水浸提液的石油醚、乙酸乙酯和水萃取物中,0.01、0.02和0.04 g·mL-1石油醚或乙酸乙酯萃取物以及0.02和0.04 g·mL-1水萃取物对番茄种子萌发及幼苗根长和茎高均有一定的抑制作用,且随质量浓度的降低,抑制率逐渐降低;其中,乙酸乙酯萃取物的抑制作用最强,水萃取物的抑制作用最低.薄层层析显色结果表明,龙柏枝叶水浸提液乙酸乙酯萃取物的主要除草活性成分为酚类成分.     

紫藤瘤不同溶剂提取部位抗农作物病原真菌活性研究

采用十字交叉法测定紫藤瘤不同溶剂提取物对农作物病原真菌的抑制作用。结果表明:紫藤瘤水提取物在5 mg?mL 1浓度下几乎无抗真菌活性。石油醚、乙酸乙酯和正丁醇提取物在5 mg?mL 1浓度下对辣椒枯萎、小麦赤霉病菌的抑菌率在50%左右,对油菜菌核菌的抑菌效果显著,抑制率高达100%。     

黄蜻幼虫肠道真菌QTYC-51的鉴定及其除草活性成分

【目的】鉴定黄蜻幼虫肠道中具有除草活性的真菌,并分析其除草活性成分。【方法】通过形态学观察和分子生物学5.8S r DNA-ITS序列分析,明确菌株QTYC-51的分类地位。结合培养皿生物分析法测定菌株发酵液和单体化合物的除草活性,采用色谱方法从该菌乙酸乙酯粗提物中分离活性成分,并利用质谱和核磁共振谱鉴定活性物质。【结果】菌株QTYC-51被鉴定为拟盾壳霉属菌(Paraconiothyrium sp.),其发酵液对稗草和反枝苋幼根生长有较好的抑制作用,抑制率分别为76.9%和56.5%。从QTYC-51发酵产物中分离到5个单体化合物,分别为1,8-dihydroxyanthraquinone,1-hydroxy-10-methoxy-dibenz[b,e]oxepin-6,11-dione,hydroxyvertixanthone,globosuxanthone和1,3,6,8-tetrahydroxyanthraquinone。在供试浓度为100μg/m L时,化合物globosuxanthone对稗草和反枝苋幼根生长有明显的抑制作用,抑制率分别为94.1%和79.0%,与阳性对照2,4-二氯苯氧乙酸效果相当;化合物1-hydroxy-10-methoxy-dibenz[b,e]oxepin-6,11-dione具有较好的除草活性,对稗草和反枝苋幼根的生长抑制率分别为50.3%和58.6%。【结论】菌株QTYC-51具有开发为微生物源除草剂的潜能。     

菊苣根提取物的抑菌活性研究

采用离体的试验方法测定了菊苣根的石油醚、乙酸乙酯和乙醇提取物对7种植物病原真菌和3种细菌的抑制活性。采用盆栽试验方法测定了菊苣根提取物对小麦白粉病的防治效果。结果表明,乙醇和乙酸乙酯提取物均有一定的抑制植物病原真菌和细菌活性。且乙酸乙酯提取物效果更佳。在10 g.L-1浓度下,乙酸乙酯提取物能显著抑制小麦赤霉病菌、玉米大斑病菌和烟草赤星病菌3种病原真菌菌丝的生长,抑制率均在85%以上;对小麦根腐病菌、玉米大斑病菌和烟草赤星病菌的孢子萌发抑制率也均在80%以上;对枯草芽孢杆菌和金黄色葡萄球菌的抑菌圈直径达21.01 mm和17.23 mm;对盆栽小麦白粉病的预防和治疗作用分别为50.93%和65.82%。     

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.     

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     

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.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

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.     

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).