Mitochondrial genome nucleotide substitution pattern between domesticated silkmoth, Bombyx mori, and its wild ancestors, Chinese Bombyx mandarina and Japanese Bombyx mandarina

Bombyx mori and Bombyx mandarina are morphologically and physiologically similar. In this study, we compared the nucleotide variations in the complete mitochondrial (mt) genomes between the domesticated silkmoth, B. mori, and its wild ancestors, Chinese B. mandarina (ChBm) and Japanese B. mandarina (JaBm). The sequence divergence and transition mutation ratio between B. mori and ChBm are significantly smaller than those observed between B. mori and JaBm. The preference of transition by DNA strands between B. mori and ChBm is consistent with that between B. mori and JaBm, however, the regional variation in nucleotide substitution rate shows a different feature. These results suggest that the ChBm mt genome is not undergoing the same evolutionary process as JaBm, providing evidence for selection on mtDNA. Moreover, investigation of the nucleotide sequence divergence in the A+T-rich region of Bombyx mt genomes also provides evidence for the assumption that the A+T-rich region might not be the fastest evolving region of the mtDNA of insects.     

Discovery of new thienopyrimidine derivatives as potent and orally efficacious phosphoinositide 3-kinase inhibitors

A series of new thienopyrimidine derivatives has been discovered as potent PI3K inhibitors. The systematic SAR studies for these analogues are described. Among them, 8a and 9a exhibit nanomolar enzymatic potencies and sub-micromolar cellular anti-proliferative activities. 8a displays favorable pharmacokinetic profiles, while 9a easily undergoes deacetylation to yield a major metabolite 8a. Furthermore, 8a and 9a potently inhibit tumor growth in a dose-dependent manner in the NCI-H460 xenograft model with an acceptable safety profile.     

Pristimerin Induces Autophagy‐Mediated Cell Death in K562 Cells through the ROS/JNK Signaling Pathway

Chronic myeloid leukemia (CML) is a lethal malignancy, and the progress toward long‐term survival has stagnated in recent decades. Pristimerin, a quinone methide triterpenoid isolated from the Celastraceae and Hippocrateaceae families, is well‐known to exert potential anticancer activities. In this study, we investigated the effects and the mechanisms of action on CML. We found that pristimerin inhibited cell proliferation of K562 CML cells by causing G1 phase arrest. Furthermore, we demonstrated that pristimerin triggered autophagy and apoptosis. Intriguingly, pristimerin‐induced cell death was restored by an autophagy inhibitor, suggesting that autophagy is cross‐linked with pristimerin‐induced apoptosis. Further studies revealed that pristimerin could produce excessive reactive oxygen species (ROS), which then induce JNK activation. These findings provide clear evidence that pristimerin might be clinical benefit to patients with CML.     

Modulation of retroviral restriction and proteasome inhibitor-resistant turnover by changes in the TRIM5alpha B-box 2 domain

An intact B-box 2 domain is essential for the antiretroviral activity of TRIM5alpha. We modeled the structure of the B-box 2 domain of TRIM5alpha based on the existing three-dimensional structure of the B-box 2 domain of human TRIM29. Using this model, we altered the residues predicted to be exposed on the surface of this globular structure. Most of the alanine substitutions in these residues exerted little effect on the antiretroviral activity of human TRIM5alphahu or rhesus monkey TRIM5alpharh. However, alteration of arginine 119 of TRIM5alphahu or the corresponding arginine 121 of TRIM5alpharh diminished the abilities of the proteins to restrict retroviral infection without affecting trimerization or recognition of the viral capsid. The abilities of these functionally defective TRIM5alpha proteins to accelerate the uncoating of the targeted retroviral capsid were abolished. Removal of the positively charged side chain from B-box 2 arginines 119/120/121 resulted in diminished proteasome-independent turnover of TRIM5alpha and the related restriction factor TRIMCyp. However, testing of an array of mutants revealed that the rapid turnover and retroviral restriction functions of this B-box 2 region are separable.     

GFP基因在新疆小拟南芥和拟南芥中的表达分析

以质粒pMCB30为模板,扩增GFP基因,连接到载体pCMBIA2300-35S-OCS上,构建过量表达载体p35S:GFP,将其转入农杆菌GV3101.通过农杆菌介导法将p35S:GFP载体分别转入新疆特色植物小拟南芥和拟南芥中.T0代经含有卡那霉素的1/2MS培养基筛选,获得了T1代转基因小拟南芥2株,T1代转基因拟南芥9株.通过激光共聚焦显微镜观察,在转基因小拟南芥和拟南芥的根尖细胞中均可检测到GFP绿色荧光蛋白;对转基因植株进行PCR扩增,均可检测到GFP基因,表明GFP基因已成功转入小拟南芥和拟南芥中.该研究建立了小拟南芥的遗传转化体系,为进一步利用GFP基因和进一步研究小拟南芥的功能基因奠定基础.     

长白落叶松冠层光合作用的空间异质性

以2014年黑龙江省帽儿山林场14年生人工长白落叶松为研究对象,对比分析了各项光合指标、环境因子及光合生理参数在冠层内的空间差异性,并探讨了净光合速率(P_n)与其他指标的关系.结果表明: 在树冠垂直方向,上层P_n、气孔导度(g_s)和蒸腾速率(T_r)显著高于中层和下层,胞间CO₂浓度(C_i)表现为下层>中层>上层;光合有效辐射(PAR)从上层外部到下层内部呈显著降低趋势,水汽压差(VPD)和叶片温度(T_l)表现为上层显著高于中层和下层,相对湿度(RH)则无显著差异;最大净光合速率(P_{n max})、暗呼吸速率(R_d)、光补偿点(LCP)和光饱和点(LSP)均表现为上层>中层>下层,下层比上层分别降低32.7%、55.8%、80.2%和51.6%,表观量子效率(AQY)表现为下层>中层>上层,下层分别是中层和上层的1.2和1.3倍.水平方向,光合指标和环境因子的差异性主要体现在树冠上层,P_n、g_s、T_r、PAR和VPD表现为树冠外部显著高于树冠内部,而C_i和RH差异不显著;P_{n max}、R_d、LCP和LSP表现为外部>内部,内部比外部分别降低0.4%、37.7%、42.0%和16.4%,而AQY在内部比外部高0.7%.C_i是限制P_n的主要生理因子,PAR是影响P_n的主要环境因子,尤其在弱光区域PAR对P_n的影响十分明显.因此,在模拟和预估树木冠层光合作用时,考虑空间异质性有一定的必要性.