毛白杨幼苗叶片生长及其光合参数和硼转运蛋白基因对高硼胁迫的响应

该研究采用毛白杨(Populus tomentosa)为试验材料,分析了温室条件下沙培幼苗对短期高硼胁迫(1、5、10 mmol/L硼酸)下的叶片生长、光合参数和硼转运蛋白的响应特征。结果显示:(1)与对照(0.05 mmol/L硼酸)相比,1 mmol/L硼酸处理导致毛白杨幼苗叶片叶绿素荧光参数上调,活性氧含量上升,树苗基部叶片出现少量黑色坏死斑;5 mmol/L硼酸胁迫下,叶片净光合速率、气孔导度和蒸腾速率下调,胞间二氧化碳浓度上升,叶绿素荧光参数和过氧化氢含量进一步上调,超氧阴离子含量较1 mmol/L硼酸胁迫时下调但仍然高于对照,除顶部叶片之外的其他叶片上出现大量坏死斑;10 mmol/L硼酸胁迫下,气体交换参数、叶绿素荧光参数和活性氧含量与5 mmol/L硼酸胁迫时相似,所有叶片均在平行于次级叶脉的方向出现呈带状分布的坏死斑。(2)毛白杨幼苗根和茎硼含量在硼胁迫条件下与对照相比变化幅度较小,而叶片硼含量在5 mmol/L和10 mmol/L硼酸胁迫下比对照显著上升,此时硼转移系数和生物富集系数均维持较高的水平。(3)硼转运蛋白(BOR)基因家族成员中PtoBOR4和PtoBOR8在根中的表达水平随着外界硼浓度的增加呈先上升后下降的趋势;在茎中,PtoBOR3基因下调表达,PtoBOR5上调表达;在叶片中,PtoBOR4表达先上升后下降,而PtoBOR7和PtoBOR8上调表达。研究表明,毛白杨幼苗叶片叶绿素荧光参数、活性氧、气体交换参数及硼转运蛋白基因家族表达对高硼胁迫较为敏感,硼胁迫症状在较短的时间内在叶片上以坏死斑的形式出现,可能与其较强的控制根系硼浓度的能力和向地上部分迅速运输硼的能力有关。     

4个品系小鼠胚胎干细胞系的建立

探索高效的不同品系的小鼠胚胎干细胞的建系方法。B6D2F1(C57BL/6×DBA/2)、129/SV×DBA/2、C57BL/6、BALB/C等4个不同品系小鼠,孕马血清促性腺激素(pregnant mare serum gonadotrophin,PMSG) 人绒毛膜促性腺激素(human chorionic gonadotropin,HCG)促排,3.5天交配后(days post coitus,dpc)冲洗子宫取囊胚,或者2.5dpc冲洗输卵管,卵裂球体外培养获取囊胚。囊胚种植到小鼠成纤维细胞饲养层上干细胞培养液培养,4～5天内细胞团扩增后玻璃毛细管挑出,种植到新的饲养层上过夜再行胰蛋白酶消化,3～4天传代一次。对所建立的小鼠ES细胞系进行形态学、染色体核型、AKP染色、体内外分化能力,干细胞分子标记物荧光免疫染色等鉴定。获得10株小鼠胚胎干细胞,具有典型的胚胎干细胞生长特性,符合ES细胞的鉴定标准。结果表明成功的建立了来自B6D2F1(C57BL/6×DBA/2)、129/SV×DBA/2、C57BL/6、BALB/C等4个不同品系小鼠的10株ES细胞系。内细胞团挑出过夜增殖后消化的培养方法可能有助于提高ES细胞的建系率。     

Perilipin 5 deficiency promotes atherosclerosis progression through accelerating inflammation,apoptosis, and oxidative stress

Excessive plasma triglyceride (TG) and cholesterol levels promote the progression of several prevalent cardiovascular risk factors, including atherosclerosis, which is a leading death cause. Perilipin 5 (Plin5), an important perilipin protein, is abundant in tissues with very active lipid catabolism and is involved in the regulation of oxidative stress. Although inflammation and oxidative stress play a critical role in atherosclerosis development, the underlying mechanisms are complex and not completely understood. In the present study, we demonstrated the role of Plin5 in high-fat-diet-induced atherosclerosis in apolipoprotein E null (ApoE^−/−) mice. Our results suggested that Plin5 expressions increased in the artery tissues of ApoE^−/− mice. ApoE/Plin5 double knockout (ApoE^−/−Plin5^−/−) exacerbated severer atherogenesis, accompanied with significantly disturbed plasma metabolic profiles, such as elevated TG, total cholesterol, and low-density lipoprotein cholesterol levels and reduced high-density lipoprotein cholesterol contents. ApoE^−/−Plin5^−/− exhibited a higher number of inflammatory monocytes and neutrophils, as well as overexpression of cytokines and chemokines linked with an inflammatory response. Consistently, the IκBα/nuclear factor kappa B pathway was strongly activated in ApoE^−/−Plin5^−/−. Notably, apoptosis was dramatically induced by ApoE^−/−Plin5^−/−, as evidenced by increased cleavage of Caspase-3 and Poly (ADP-ribose) polymerase-2. In addition, ApoE^−/−Plin5^−/− contributed to oxidative stress generation in the aortic tissues, which was linked with the activation of phosphatidylinositol 3-kinase/protein kinase B and mitogen-activated protein kinases pathways. In vitro, oxidized low-density lipoprotein (ox-LDL) increased Plin5 expression in RAW264.7 cells. Its knockdown enhanced inflammation, apoptosis, oxidative stress, and lipid accumulation, while promotion of Plin5 markedly reduced all the effects induced by ox-LDL in cells. These studies strongly supported that Plin5 could be a new regulator against atherosclerosis, providing new insights on therapeutic solutions.     

斑马鱼ca15b的克隆及在原始生殖细胞中的特异表达简

高保真PCR克隆获得了ca15b基因的全长,利用胚胎整体原位杂交等技术研究了ca15b基因在斑马鱼早期发育过程中的动态表达。结果发现,ca15b在斑马鱼早期发育过程中存在显著的原始生殖细胞(Primordial germ cell,PGC)特异表达模式。ca15b是一个母源性表达的基因:在分裂期的胚胎中,其mRNA集中分布于位于分裂沟的生殖质(Germ plasm);从囊胚期开始,可以观察到其在PGC中的特异表达;在原肠胚中,其mRNA在体细胞中急剧降解,仅特异表达于PGC,这一表达特征一直持续到受精后1d的胚胎。将体外合成的包含5′UTR和3′UTR的ca15b全长mRNA注射到斑马鱼胚胎后,仅能增强原肠期之前胚胎中ca15b的整体杂交信号;在原肠胚期之后,注射的mRNA在体细胞中快速降解。这提示在ca15b mRNA上可能存在某种转录后调控其在早期胚胎体细胞中降解而在PGC中稳定存在的机制。     

大肠杆菌基因无痕敲除技术及策略

基因敲除技术是大肠杆菌基因组减小和代谢途径改造的有效手段,其中基于同源重组原理的基因无痕敲除技术显现出其他技术所不具备的应用优势和发展潜力。该技术可以快速敲除大肠杆菌基因组中的目标基因,并且在基因组中不残留任何外源片段,所以不会干扰后续的基因操作。我们分类介绍了无痕敲除技术中所涉及载体的结构、功能及其相应的敲除策略,着重介绍了无痕敲除技术的原理及载体构建方法。     

不同冠温特征冬小麦籽粒灌浆过程中内源激素含量的变化

"豫麦50"在灌浆后期冠层温度明显降低,表现为冷尾型;而"豫麦34"和"豫麦70"则在灌浆后期冠层温度有上升趋势,表现为暖尾型,在灌浆末期冷尾型与暖尾型小麦冠层温度相差超过2.5℃.冷尾型"豫麦50"强势粒中ZR、IAA、GA3含量峰值均高于其它两个品种,其ZR/ABA、GA3/ABA、IAA/ABA峰值亦高于暖尾型"豫麦70"和"豫麦34",ABA含量在灌浆中期上升快,高峰值大于"豫麦70"和"豫麦34",达到高峰后下降较快;"豫麦50"弱势粒中的各种激素含量仍较高.     

外源甜菜碱对黄瓜幼苗抗冷性的影响

以5 mmol·L-1甜菜碱(GB)根施黄瓜幼苗24h,可缓解低温胁迫[(6±1)℃]5 d后的叶中叶绿素含量的下降,保持相对较高的净光合速率和抗氧化酶活性,削弱丙二醛(MDA)积累,保持细胞膜的相对完整性,提高幼苗存活率.     

高温胁迫对‘黄冠’、‘翠玉’梨耐热生理指标及相关基因表达的影响

为探讨高温胁迫对梨树的影响,对2年生‘黄冠’(Pyrus pyrifolia‘Cuiguan’)、‘翠玉’(P.bretschneideri×P.pyrifolia)盆栽苗胁迫后叶片的抗氧化物质、抗氧化酶、渗透物质和激素的变化进行了测定,利用q RT-PCR分析了叶片中抗性基因的表达。结果表明,在高温胁迫下,梨树叶片的叶绿素含量明显下降,而MDA含量则持续上升;梨叶片中的POD和CAT活性总体呈下降趋势,但‘黄冠’的POD和CAT活性均高于‘翠玉’;PRO含量随胁迫时间延长逐渐增加;ASA含量表现出先上升后下降,且‘黄冠’的ASA含量高于‘翠玉’;IAA和ABA含量都随胁迫时间的延长呈下降趋势,但‘黄冠’的IAA和ABA含量比‘翠玉’高。q RT-PCR结果表明,叶片中相关基因的表达量与对应的ASA、IAA和ABA含量变化趋势基本一致。因此,‘黄冠’比‘翠玉’抗高温性能强,且高温处理第4天为‘黄冠’和‘翠玉’梨的生理变化转折点。