火鹤花的组织培养

对火鹤花进行组培实验。1）用幼嫩的叶片和1／2MS培养基进行初代培养,继代培养培养基又恢复正常的MS,此点与以往的组培初代培养培养基的配方有区别。2）初代启动培养时间（6—8周）和继代培养（45d）周期很长与其他植物组培也有所区别。3）火鹤花因为极易生根且叶片革质不易失水,所以炼苗极其容易。实验证明,火鹤花的组培苗驯化成苗率达95％以上．使得火鹤花苗完全可以工厂化生产。     

棉花纤维品质与气象因子的定量分析

2002～2003年在南京、安阳、保定和石河子4地用"异地分期种植比较法"研究了气温及日照条件与棉花纤维品质的关系.结果表明,随纬度升高,由中熟棉区向北疆早熟棉区推移过程中,纤维加长,比强度下降,麦克隆值降低,可溶性糖含量增加.在建立棉花纤维比强度、麦克隆值和可溶性糖含量与温度和日照时数的生态模型的基础上,确定了棉铃发育期适宜温度范围或临界值.若以获得长度≥27 mm的优质纤维为先决条件,则分别以铃期日均温21.3～29.7℃、最低气温10.7～21.3℃、最大日温差不超过15.2℃为宜,日均温为25.4℃时,纤维最长;若以获得具有国际竞争优势的最低纤维长度(≥25 mm)为先决条件,则分别以铃期日均温不低于15.5℃、最低气温不低于10.7℃、最大日温差不超过17.9℃为宜.     

气候变化背景下中国农业气候资源变化Ⅸ.中国农业气候资源时空变化特征

利用中国558个气象台站1961-2007年地面气象观测资料,分析了不同区域农业气候资源变化的差异,并分析和比较了1961-1980年(时段Ⅰ)和1981-2007年(时段Ⅱ)的农业气候资源变化特征.结果表明： 与时段Ⅰ相比,时段Ⅱ中国年均气温增加了0.6 ℃,喜凉作物生长期内≥0 ℃积温和喜温作物生长期内≥10 ℃积温分别平均增加123.3和125.9℃·d;1961-2007年,年均气温增幅最大的区域是东北地区,喜温作物生长期内≥10 ℃积温增幅最大的是华南地区.对全国而言,与时段Ⅰ相比,时段Ⅱ在全年、喜凉和喜温作物生长期内日照时数分别减少了125.7、32.2和53.6 h;1961-2007年,长江中下游地区年日照时数的减幅最多,喜凉和喜温作物生长期内日照时数减少量最大的地区分别是华北和华南地区;在全年、喜凉和喜温作物生长期内,中国的降水量和参考作物蒸散量总体均表现为减少趋势,其中,华北地区在全年、喜凉和喜温作物生长期内降水量的减幅均最大,长江中下游地区参考作物蒸散量在全年和喜温作物生长期内的减幅最大,西北地区参考作物蒸散量在喜凉作物生长期内的减幅最大.研究期间,中国气候在全年和喜温作物生长期内总体表现为暖干趋势,其中,喜温作物生长期内西南、华北和东北地区为暖干趋势,长江中下游、西北和华南地区为暖湿趋势,喜凉作物生长期内华北地区为暖干趋势,西北地区为暖湿趋势.     

灌浆期高温对水稻光合特性、内源激素和稻米品质的影响

以2个籼稻品种:温度钝感型品种K30和温度敏感型品种R21为材料,利用人工气候室控温,在水稻灌浆期设置高温(日均温度34.9℃)和适温(日均温度28.0℃)处理,测定不同灌浆时期(5,10,15,20,25d和30d)光合特性、内源激素含量及稻米品质的变化。结果表明,高温增强了K30的光合能力,K30高温处理净光合速率(Pn)在整个灌浆期都明显高于对照;R21在灌浆前期(5、10d和15d)高温处理与适温处理Pn差异不明显,在灌浆后期(20、25d和30d)高温处理Pn下降。高温增加了K30叶片和籽粒脱落酸(ABA)含量;而R21高温处理和适温处理叶片与籽粒ABA含量的对比不明显。高温处理对两个水稻品种叶片和籽粒赤霉素(GA3)与生长素(IAA)含量也有不同程度影响。高温胁迫降低稻米品质,但K30比R21表现出更强的温度钝感特性。     

高温对早籼稻花后剑叶氮代谢关键酶活性及籽粒蛋白质含量的影响

为探讨高温对不同类型早籼稻开花后剑叶中氮代谢关键酶活性及籽粒蛋白质含量的影响,利用人工气候室在籽粒灌浆成熟期进行高温(日均温31.5 ℃)和适温(日均温23.5 ℃)处理,对2个早籼稻品种(湘早籼24和株两优611)灌浆成熟期籽粒中蛋白质含量及剑叶中GS和GOGAT活性的动态变化进行了分析.结果表明:供试2个品种在高温...     

结实期相对高温对稻米淀粉粘滞性谱及镁、钾含量的影响

选用武育粳3号(粳稻)和扬稻6号(籼稻)两个水稻品种,利用人工气候室在水稻灌浆结实期进行控温试验,设置全结实期相对高温、结实前期相对高温、结实后期相对高温、全结实期适温(对照,日均温23 ℃)对照4个处理,探讨结实期不同时段相对高温(日均温度-30 ℃)对稻米淀粉粘滞性谱和Mg、K等元素含量的影响.结果表明：结实期相对高温使武育粳3号和扬稻6号淀粉粘滞性谱特征值发生改变,其中糊化开始温度、冷胶粘度、回复值和消减值升高,最高粘度、热浆粘度和崩解值下降;结实期相对高温促进了米粉中Mg、K、N含量的提高,特别是K含量的大幅提高,使稻米中Mg/K和Mg/(N·AC·K)明显降低;而2个水稻品种的直链淀粉含量（AC）对相对高温的反应截然相反,武育粳3号的AC降低、扬稻6号的AC升高.全结实期相对高温对稻米淀粉粘滞性谱和Mg、K等元素含量的影响最大,结实前期其次,结实后期的影响较小,开花后20 d内是稻米淀粉粘滞性谱和Mg、K等元素含量受温度影响的关键时期.Mg/K和Mg/(N·AC·K)与淀粉粘滞性谱特征值显著相关,可以作为稻米食味品质评价的参考指标.     

福建省水稻生育期气温与降水的时空分布及其对稻作制度的影响

为了研究气候变化对福建省水稻生产及稻作制度的影响,根据IPCC排放情景特别报告(SRES)的A2、B2和A1B方案,分析了未来不同情景下,福建省水稻生育期气温及降水的时空分布特征及水稻种植布局变化.结果表明:未来福建省水稻生育期的温度将呈上升趋势,随着时间的推移,增温幅度加大.单季稻生育期增温幅度最大,2011-2030年和2031-2050年分别增加0.3～2.4℃和1.5 ～3.4℃;早稻生育期两个时段分别增加0.2 ～0.9℃和0.7～1.7℃;后季稻生育期两个时段分别增加0.3～2.1℃和0.5～3.6℃,且日均温的年际波动幅度最大.降水多呈增加趋势,早稻、单季稻和后季稻生育期降水分别增加10％～40％、10％～30％和10％～20％;闽东南早稻生育期的降水年际波动最大.未来气温的上升导致了10℃以上积温增加,水稻生长季延长,使用晚熟品种替代早熟和中熟品种及单季稻种植区改种双季稻成为可能.     

稻米垩白形成的气象生态基础研究

在全国13个点、19个品种多播期试验基础上,对稻米垩自形成的气象生态基础进行了分析。结果表明,水稻齐穗后15天的日均温是影响稻米垩白大小的主要气象因子。经对稻米垩白与齐穗后15天内均温关系的动态分析可知,稻米垩白随该时段温度提高而增大的拐点温度约为29℃(品种间略有差异),接近或超过该点温度,稻米垩白会突发性地增加。     

不同温度对烟草生长发育及光合作用的影响

该试验通过人工气候室模拟相对低温(日均温16.5℃)、常温(日均温23.5℃)和相对高温(日均温30.5℃)3种日动态温度,研究了不同温度对烟草生长发育及光合作用的影响。结果表明:(1)与常温下生长的烟草相比,相对低温和高温处理均降低了烟株的株高、叶长和叶宽,在一定程度上抑制了烟草的生长。(2)相对低温和高温处理比常温处理下有较低的烟叶净光合速率(Pn)、胞间CO_2浓度(Ci)、气孔导度(Gs)、蒸腾速率(Tr)、PSⅡ最大光化学量子效率(F_v/F_m)、PSⅡ实际光化学量子效率(ΦPSⅡ)、光化学猝灭系数(qp)、Rubisco羧化酶活性和相对较高的初始荧光强度(F0)。长期较高或较低的温度均会对烟草的生长发育产生抑制,这可能因其在一定程度上抑制了烟叶的光合机构活性并对反应中心造成了损伤,从而降低了烟草的光合作用,抑制了烟株的生长,长期日均温23.5℃有利于烟草的生长和光合作用。     

水稻三系不育系育性与温度关系研究

通过自然条件下分期播种实验,对生产上应用的12个三系不育系花粉育性与温度的关系进行比较分析。结果表明:自然高温条件下不育系金23A、T98A、丰源A及冈46A花粉不育性稳定;隆398A、隆香634A、4302A、优IA及D62A出现少量可染花粉;高温诱导天丰A、五丰A和粤泰A花粉可育作用明显。此外,对可染花粉率与水稻不同发育时期的日均温相关性的分析表明,五丰A、天丰A和粤泰A可染花粉率均与抽穗前13~18 d的日均温显著相关(P0.05),高温诱导五丰A、天丰A和粤泰A育性转换敏感期为雌雄蕊原基形成末期至减数分裂期,育性转换临界日均温度分别为27.11℃、26.48℃和27.30℃。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

Synthesis and antimicrobial studies of hydrazone derivatives of 4-[3-(2,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid and 4-[3-(3,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid

Microbial resistance to antibiotics is an unresolved global concern, which needs urgent and coordinated action. One of the guidelines of the Centers for Disease Control and Preventions (CDC) to combat antibiotic resistance is the development of new antibiotics to treat drug-resistant bacteria. In our effort to find new antibiotics, we report the synthesis and antimicrobial studies of 30 new pyrazole derivatives. These novel molecules have been synthesized by using readily available starting materials and benign reaction conditions. Some of these molecules have shown activity with MIC values as low as 0.78?µg/mL against four bacterial strains; Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, and Acinetobacter baumannii. Furthermore, active molecules are non-toxic to mammalian cell line.

     

Novel compounds with potent CDK9 inhibitory activity for the treatment of myeloma

Cyclin-dependent kinases (CDKs) and Polo-like kinases (PLKs) play key role in the regulation of the cell cycle. The aim of our study was originally the further development of our recently discovered polo-like kinase 1 (PLK1) inhibitors. A series of new 2,4-disubstituted pyrimidine derivatives were synthesized around the original hit, but their PLK1 inhibitory activity was very poor. However the novel compounds showed nanomolar CDK9 inhibitory activity and very good antiproliferative effect on multiple myeloma cell lines (RPMI-8226).