水稻花药液体培养下影响愈伤组织诱导和分化的一些因素的研究

水稻花药液体漂浮培养能大幅度提高愈伤组织诱导频率,但这些愈伤组织的分化能力很低。为了提高液体培养下愈伤组织的分化频率,试验了5种诱导培养基和4种分化培养基。结果表明,诱导培养基对愈伤组织分化能力的高低起主要作用,其中以过滤灭菌的马铃薯提取液培养基的效果最好,绿苗分化率可高达50％;分化培养基对愈伤组织分化频率的影响较小,且不甚规律。浮在液面上的愈伤组织比沉在培养液底部的愈伤组织有较高的分化能力。愈伤组织转移时间的早晚对分化频率也有很大影响。     

提高小麦愈伤组织分化频率的因素

研究了影响小麦愈伤组织诱导、芽分化及其植株再生的一些因素。结果表明：在愈伤组织诱导和继代过程中添加ＡＢＡ（１．０ｍｇ／Ｌ）有利于小麦中晚期幼胚致密愈伤组织的诱导及再生能力的保持;外植体来源尤其是基因型对长期培养的愈伤组织再生能力有很大影响;不同的外源激素（ＫＴ、６－ＢＡ、ＩＡＡ、ＴＤＺ和玉米素等）也影响芽分化频率,其中ＴＤＺ可明显提高芽分化频率;在转入分化培养前对愈伤组织进行干燥处理可有效地提高其     

提高小麦愈伤组织分化频率的因素

研究了影响小麦愈伤组织诱导、芽分化及其植株再生的一些因素。结果表明：在愈伤组织诱导和继代过程中添加ＡＢＡ（１ ．０ｍｇ／Ｌ） 有利于小麦中晚期幼胚致密愈伤组织的诱导及再生能力的保持;外植体来源尤其是基因型对长期培养的愈伤组织再生能力有很大影响; 不同的外源激素（ ＫＴ、６ＢＡ、ＩＡＡ、ＴＤＺ和玉米素等） 也影响芽分化频率,其中ＴＤＺ可明显提高芽分化频率;在转入分化培养前对愈伤组织进行干燥处理可有效地提高其芽分化频率;在生根培养基中添加适量的ＩＡＡ 或ＮＡＡ 可有效促进生根。     

提高小麦原生质体再生植株频率的研究

从小麦徐州211的成熟种子诱导愈伤组织,建立了胚性悬浮细胞系。酶解悬浮细胞获得原生质体,用含o．8％琼脂糖的改良Ms培葬基进行琼脂糖珠培养,再生细胞分裂,并形成愈伤组织。诱导再生愈伤组织分化．得到了完整的再生植株。原生质体培养两周后,加入降渗培养液可促进克隆的形成。在分化培养基中,低浓度蔗糖可提高植株分化率。高浓度的激动索和玉米素对芽的分化有效并能抑制愈伤化。再生愈伤组织诱导分化时期的早晚影响植林分化频率。     

烟草愈伤组织分化和芽原基形成期间呼吸代谢途径的改变

接种在继代培养基上的柳叶烟草愈伤组织,未观察到组织分化和芽原基形成。在分化培养基上生长的愈伤组织,接种后第6天可见拟分生组织和管胞分化,9—12天有芽原基形成,15—18天可观察到苗端结构。根据碘乙酸、Na_3PO_4和丙二酸抑制试验,以及3-磷酸甘油醛脱氢酶与琥珀酸脱氢酶活性测定结果,初步表明烟草愈伤组织呼吸中存在有EMP、HMP和TCAC代谢途径.在发生输导组织和芽原基分化的愈伤组织中(接种后第6—12天),HMP途径的运行程度较高;而芽原基的继续生长(培养12天以后),则与EMP途径的增加有关;分化培养基上生长的愈伤组织,始终较继代培养愈伤组织具有较高的FCAC活性水平。     

籼稻花药培养的研究——提高愈伤组织诱导率与分化率及根芽分化

3年来通过对籼稻(Oryza sativa subsp.hsien)花药培养的研究,愈伤组织的诱导率从0.2%提高到平均为2.85%,最高达18.75%;绿苗分化率从5%以下提高到平均为13.1%最高达到45.5%。在6个籼稻品种、38个籼×籼杂种中成功地诱导出了绿苗。本文着重研究了提高诱导率的有关因素。以单核晚期花粉的花药愈伤组织诱导频率最高。籼稻花粉去分化过程相对地要求较低浓度的培养基,籼稻花药对高浓度的改良 RM-1964培养基完全没反应。用杂种的诱导率较亲本材料为高。以易于诱导愈伤组织或易于分化绿苗的品种作亲本的杂种后代,诱导率与绿苗分化率亦较高。籼稻形成愈伤组织的高峰是在接种后的50—60天之间。愈伤组织分化的高潮是在转移后10—30天之间。籼稻愈伤组织的分化以先分化根的类型最多,在先分化根的愈伤组织中有36.74%能再分化出芽来。     

提高疣粒野生稻愈伤组织分化能力的研究

通过低温处理、更换培养基凝固剂以及液固交替培养的方式,成功地保持了疣粒野生稻愈伤组织的胚性,提高了绿苗分化率。结果表明：低温处理12天的愈伤组织绿苗分化率最高;用琼脂糖代替琼脂作为培养基凝固剂,能在较大程度上提高愈伤组织绿苗分化率;通过液固交替培养的方式保持了悬浮系的分化潜能,在悬浮培养18个月后,绿苗分化率仍达到41.6％,而持续悬浮培养12个月的愈伤组织全部丧失分化能力。酯酶同工酶分析表明：部分酶带的丢失与愈伤组织分化能力的丧失有关。     

提高疣粒野生稻愈伤组织分化能力的研究

通过低温处理、更换培养基凝固剂以及液固交替培养的方式,成功地保持了疣粒野生稻愈伤组织的胚性,提高了绿苗分化率。结果表明：低温处理１２ 天的愈伤组织绿苗分化率最高;用琼脂糖代替琼脂作为培养基凝固剂,能在较大程度上提高愈伤组织绿苗分化率;通过液固交替培养的方式保持了悬浮系的分化潜能,在悬浮培养１８ 个月后,绿苗分化率仍达到４１ ．６ ％ ,而持续悬浮培养１２ 个月的愈伤组织全部丧失分化能力。酯酶同工酶分析表明：部分酶带的丢失与愈伤组织分化能力的丧失有关     

以耐草甘膦2mG2-epsps基因为选择标记的玉米转化体系的建立

转化细胞的筛选和再生是植物遗传转化体系中重要的组成部分,筛选剂的选择和筛选压力的高低直接影响着外源基因的转化率。以草甘膦异丙胺盐为筛选剂,通过比较在不同的草甘膦浓度及筛选时间的条件下,玉米愈伤组织生长和分化情况,发现经1mM的草甘膦异丙胺盐筛选15d后玉米愈伤组织分化受到明显抑制,故以此作为玉米遗传转化实验中的筛选压力。通过基因枪轰击,将构建好的pMAGUHM载体（其上携带有抗草甘膦基因2mG2-epsps基因）转化到玉米愈伤组织,利用草甘膦筛选得到耐草甘膦植株80株,其中PCR检测阳性植株为36株,转化率为45％。     

结球甘蓝离体下胚轴愈伤组织的维管组织及管状分子

结球甘蓝离体下胚轴培养初期,在切口较深层发现的维管组织结节,是由外植体维管组织衍化的。愈伤维管组织既可由愈伤薄壁细胞分化,也可由愈伤形成层分化。愈伤形成层向内分化导管分子,向外没有发现筛分子的分化。愈伤维管组织有不同的形态,起初常各不相连,后和外植体维管组织衔接。芽的再生起初和愈伤维管组织没有直接的联系,后原形成层自上而下分化,逐渐与愈伤维管组织相连接。不定根发生于维管组织结节的单向极性分化,始终     

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.