美洲黑杨×小叶杨杂种多倍体诱导研究

用不同浓度秋水仙素处理美洲黑杨(Populus deltoides)与小叶杨(Populus simonii)杂种后代以诱导产生多倍体,并采用流式细胞术(FCM)对初选的多倍体材料进行DNA含量分析.结果表明:小于0.1%秋水仙素浓度处理对诱导多倍体无作用;0.3%及其以上浓度处理对诱导产生多倍体效果较好,但随处理浓度增加秋水仙素对杨树的毒害作用增大, 0.5%浓度处理可使顶芽死亡率高达71.43%,且在顶芽死亡的植株中未发现多倍体单株.应用气孔性状对388株扦插苗进行多倍体初选后,采用流式细胞术对初选的5株拟多倍体进行DNA含量分析,鉴定到2株四倍体材料.获得的四倍体材料与二倍体植株在株高和叶绿素含量上差异显著,但在SOD和POD活性上无显著性差异.     

秋水仙碱诱变甜菊多倍体的研究

用０．１％秋水仙碱溶液处理甜菊实生苗生长点,可诱变产生甜菊多倍体（四倍体）植株,用８次点滴处理,诱变率可达３１．２５％。染色体数鉴定表明：四倍体甜菊染色体数是２ｎ＝４４,而二倍体甜菊染色体数是２ｎ＝２２．形态学和解剖学的观察表明,四倍体比二倍体甜菊植株的茎矮壮,叶片增大,长度增长２．１倍,宽度扩大２．３倍,叶片加厚１．７倍,叶色更浓绿,叶片气孔数减少,气孔变大。叶片糖苷含量测定表明：四倍体的叶片含量为１５．７％,而二倍体的叶片含量为１０．８％,前者比二倍体叶片含量提高４．９％。     

秋水仙碱诱导重瓣大岩桐(Sinningia speciosa)多倍体的研究

以重瓣大岩桐叶片为外植体,经秋水仙碱处理得到大量的多倍体植株。在培养基中加入秋水仙碱２０ｍｇ Ｌ＾－１处理一周,可使重瓣大岩桐的诱变率达到６２．５％,对再生植株进行形态学观察表明,多倍体植株比二倍体的茎粗壮,叶片增大,加厚。细胞学鉴定四倍体染色体数为２ｎ＝４ｘ＝５２,而二倍体的染色体数为２ｎ＝２６。     

广藿香毛状根多倍体诱导及其植株再生

为了提高药用植物广藿香的次生物质广藿香醇含量,采用秋水仙素人工诱导染色体加倍技术,进行了广藿香毛状根多倍体诱导及其植株再生、倍性鉴定和挥发油组分广藿香醇含量的测定。结果表明,广藿香毛状根多倍体诱导的最佳条件为0.05%秋水仙素处理36 h,其多倍体诱导率可达40%以上;经秋水仙素加倍的广藿香毛状根在MS+6-BA 0.2 mg/L+NAA 0.1 mg/L培养基中培养60 d后可获得毛状根多倍体再生植株。与对照(二倍体植株)相比,广藿香毛状根多倍体再生植株根系更发达、茎更粗、节间变短、叶片的长度、宽度和厚度均较二倍体明显增大。根尖细胞染色体压片观察证实,所获得的广藿香毛状根多倍体再生植株为四倍体,其根尖细胞染色体数约为128;同时,其叶片的气孔保卫细胞体积及其叶绿体数目均约为对照的两倍;但其气孔密度则随着倍性增加而下降,二倍体植株叶片的气孔密度约为四倍体植株叶片的1.67倍。GC-MS测定结果表明,广藿香毛状根多倍体再生植株的广藿香挥发油组分广藿香醇的含量为4.25 mg/g干重,约为二倍体植株的2.30倍。该结果证实毛状根多倍体化可提高药用植物广藿香的广藿香醇含量。     

野生南荻与芒杂种多倍体诱导研究

用不同浓度秋水仙素处理野生南荻×芒(Miscanthus lutarioriparia×Miscanthus sinensis)远缘杂交后代以诱导产生多倍体,并对变异株进行形态学和细胞学鉴定,以期获得稳定的四倍体植株并分析其生理特性。结果表明:(1)采用秋水仙素加入培养基处理法和秋水仙素溶液浸泡处理法都可获得一定频率的多倍体植株;胚性愈伤组织以0.2%秋水仙素浸泡处理48h的诱变效果较好,四倍体诱导率达8.7%;芽在0.05%秋水仙素培养基中处理15d较好,四倍体诱导率达10.6%;生根苗在0.1%秋水仙素培养基中处理10d较好,四倍体诱导率达11.1%。(2)经体细胞染色体计数,加倍植株染色体数为2n=4x=76,对照植株的染色体数目为2n=2x=38。(3)生长2年的多倍体植株形态、叶片大小、茎粗、茎壁厚、节间等性状表现出巨大性和超亲优势。     

彩色马蹄莲品种‘Parfait’多倍体诱导及其生物学特征变化

以彩色马蹄莲品种‘Parfait’（Zantedeschiahybrid‘Parfait’）离体丛生芽块为实验材料,对其多倍体诱导过程中秋水仙素和二甲基亚砜（DMSO）浓度以及浸泡时间进行分析,并比较了多倍体与二倍体植株在叶形指数、气孔特征、叶绿素含量和染色体数的差异,最终通过回归分析确定最佳诱导条件。结果显示：随秋水仙素质量体积分数的提高及浸泡时间的缩短,各处理组的丛生芽存活率逐渐增加且均低于对照,而多倍体诱导率逐渐降低且均显著高于对照。综合考虑丛生芽存活率和多倍体诱导率等因素,根据回归分析确定‘Parfait’多倍体诱导的最佳条件为：丛生芽块在含质量体积分数0.20%秋水仙素和体积分数0.10%DMSO的MS液体培养基中浸泡24h,多倍体诱导率可达50.02%。比较分析结果表明：多倍体植株的叶片长度、厚度和长宽比分别为二倍体植株的1.23、1.19和2.93倍,保卫细胞的长度和宽度以及每气孔叶绿体数分别为二倍体植株的1.90、1.96和2.03倍,叶绿素a和总叶绿素含量分别为二倍体植株的1.28和1.17倍;但多倍体植株的叶宽和气孔密度均较小,分别仅为二倍体植株的42.08%和61.55%。除叶绿素b含量外,多倍体植株的其他生物学特性均与二倍体植株差异显著。染色体计数结果显示：获得的多倍体大多为四倍体,染色体数为2n=64,同时还得到了一些嵌合体和六倍体。研究结果表明：彩色马蹄莲品种‘Parfait’多倍体植株的多数生物学特性优于二倍体植株,且其对环境的适应性更强。     

紫锥菊多倍体诱导与鉴定

本实验以紫锥菊愈伤组织上刚分化出的不定芽为材料,用不同浓度秋水仙素溶液对其进行诱导,确定最佳处理浓度和处理时间,并对诱导的多倍体与二倍体进行形态、显微、染色体及过氧化氢酶(CAT)活性的比较鉴定.结果表明:0.025%秋水仙素浓度处理24h的诱导效果最好,诱导率达42.85%;多倍体植株叶片肥厚、根粗壮,气孔面积极显著地大于二倍体植株,染色体数从24～28条不等,CAT平均酶活性是二倍体的2.1倍.     

秋水仙素诱导川贝母(Fritillaria cirrhosa D.Don)愈伤组织多倍体的研究

应用组织培养技术对川贝母（Fritillaria cirrhosaD.Don)进行多倍体诱导。结果表明：组织培养条件下,将川贝母愈伤口组织在培养基中添加一定浓度的和为水仙素处理一段时间,或者经一定浓度的和为水仙素浸泡一段时间后再培养,均可诱发川贝母多倍体的产生,但以前者效果较好。在秋水仙素浓度为1000mg/L。处理5d的条件下,诱导率最高达70%。细胞染色体鉴定结果为：四倍体染色体数为2n=4x=48,而二倍体的染色体数为2n=2x=24。     

秋水仙素对草莓离体叶片再生和多倍体诱导的影响

以草莓(Fragaria×ananassa Duch.)栽培品种'雪蜜'(2n=8X=56)的离体叶片为外植体,研究了不同浓度秋水仙素对愈伤组织诱导率、不定芽再生率以及多倍体植株诱导的影响,并采用流式细胞仪对多倍体植株的倍性进行鉴定.结果显示,用质量体积分数0.1%、0.3%、0.5%和0.7%的秋水仙素浸泡2、4和6 d,草莓离体叶片均能诱导出愈伤组织和不定芽,但随秋水仙素浓度的提高和处理时间的延长,愈伤组织诱导率和不定芽再生率均显著下降.用不同浓度秋水仙素处理均能产生多倍体植株,倍性为9X、10X、11X、12X、14X和16X;随秋水仙素浓度的提高,多倍体诱导率呈现先上升后下降的变化趋势.用质量体积分数0.3%秋水仙素浸泡处理4 d是最佳的草莓离体叶片诱导方法,不定芽再生率达到40.5%,多倍体诱导率为100.0%,并且诱导产生出16X的植株.     

甜叶菊同源四倍体离体诱导及鉴定

用不同浓度秋水仙素溶液处理甜叶菊不定芽,诱导同源四倍体,并进行解剖学、染色体鉴定和流式细胞仪鉴定倍性。结果表明:(1)用0.20%的秋水仙素溶液浸泡甜叶菊不定芽12h,同源四倍体诱导率最高,可达32.14%。(2)同源四倍体植株与二倍体(对照)相比,其气孔、叶片等均表现巨大性,且叶片变厚、叶色浓绿、叶片皱缩。(3)对照植株染色体2n=2x=22,四倍体植株染色体2n=4x=44;流式细胞仪倍性鉴定结果显示,对照DNA相对含量为100,四倍体DNA相对含量为200。(4)该研究共鉴定出48株甜叶菊同源四倍体植株,为进行倍性植株的诱导奠定了技术基础,为进一步开展甜叶菊同源四倍体新品种的选育提供了实验材料。     

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.