超甜玉米种子萌发物质利用性状杂种优势及亲子回归关系分析

为阐明超甜玉米(Zea mays L.var.saccharata Bailey)亲本对F_1种子物质利用性状遗传效应,研究了19份自交系和其测配的10个杂交组合的杂种优势及亲子回归关系。结果表明,超甜玉米自交系及F_1种子的淀粉含量、蛋白质含量、脂肪含量、百粒重、种子物质动用量和种子物质利用率差异较大,10个杂交组合中亲本和F_1种子的淀粉含量、脂肪含量、百粒重均存在显著差异。F_1种子淀粉含量和百粒重均表现出正向超亲优势,即近高亲本遗传;而F_1种子的蛋白质含量、脂肪含量、种子物质动用量和种子物质利用率为近低亲本遗传。聚类分析和杂种优势分析表明,性状差异较大的FH14、Q26、GT22、GT2等亲本测配的杂交组合在种子百粒重或种子物质利用率等性状上具有较强的超亲优势。回归分析表明,母本对F_1种子的淀粉含量、百粒重有负效应,对种子物质动用量和种子物质利用率有正效应;父本对种子淀粉含量有负效应,对种子物质利用率有正效应。     

上海郊区黑斑蛙皮中两个新肽的分离和结构鉴定

<正> 黑斑蚌(Rana nigromaculata)皮的甲醇提取物经碱性氧化铝层析,所得50％乙醇洗脱液冻干后用反相HPLC分离得到18组峰。其中第9—10组峰与第15组峰进一步统化得9-10-10(Fig.1)与15-5-2(Fig.2)。按文献方法所得氨基酸组成分析结果分别是:     

钙调素依赖性环核苷酸磷酸二酯酶的简易粗提法

<正> 钙调素依赖性环核苷酸磷酸二酯酶(camodulindependent cyclic nucleotide phosphodiesterase, CaM-PDE)是研究环核苷酸和钙调素酶法测定必备的工具。由于其稳定性较差,不能长期保存,需经常提取。传统提取方法采用冷室中线性离子梯度DEAE纤维素柱层析与其它层析并用。本法利用DE_(52)柱层析,阶段离子浓度洗脱。纯化CaM-PDE近20倍。在足够的钙调素(CAM)存在下可激活10倍。     

植食性非鸟恐龙胃(肠)容物研究综述*

胃(肠)容物是一类稀有的化石记录, 可以为古食谱研究提供直接证据。1909年以来, 仅有十几例植食性非鸟恐龙的胃(肠)容物报道, 标本涵盖蜥脚类(Sauropoda)、兽脚类(Theropoda)、鸭嘴龙科(Hadrosauridae)、有甲类(Thyreophora)四个主要类群。对胃(肠)容物中植物材料的形态学、分类学鉴定, 辅以孢粉学和地球化学分析, 可以揭示死亡个体的最后一餐, 并为植食性恐龙的消化系统、取食行为以及它们与中生代植物之间的协同演化提供证据。但植物材料的来源(如是否通过流水引入)往往不易判断, 使一部分标本存在争议。此外, 鉴于其特异保存能力, 中国东北热河、燕辽两个生物群的标本值得格外关注。文中回顾了植食性恐龙胃(肠)容物的研究进展和方法学, 并阐述了该材料所蕴含的演化生物学、古环境学及古生态学意义。     

iTRAQ-based quantitative analysis reveals the mechanism underlying the changes in physiological activity in a glutamate racemase mutant strain of Streptococcus mutans UA159

Molecular Biology Reports - Streptococcus mutans UA159 is responsible for human dental caries with robust cariogenic potential. Our previous study noted that a glutamate racemase (MurI) mutant...     

耻垢分枝杆菌ClpC和ClpX敲低表达菌株的构建及表型分析*

蛋白质平衡稳定对细菌的生长繁殖以及应对宿主免疫压力十分重要。Clp蛋白酶复合体在结核分枝杆菌的蛋白质降解和平衡稳定中发挥重要作用。Clp蛋白酶中负责识别底物蛋白并将其解折叠的蛋白质有两种:ClpC和ClpX。为初步探究分枝杆菌中ClpC和ClpX各自的功能特点,运用CRISPRi的方法成功构建了耻垢分枝杆菌的ClpC和ClpX诱导型敲低表达菌株,并对其生长相关表型进行分析。结果显示:与野生菌株相比,ClpC和ClpX的低表达均能严重影响耻垢分枝杆菌的生长。ClpC低表达可导致菌株丧失生物膜的形成能力,而ClpX低表达则导致菌株无法维持正常细胞形态,电镜显示细胞壁不完整且细胞呈丝状化,提示ClpC和ClpX可能在分枝杆菌中具有不同的生理功能。可为后期深入开展ClpC和ClpX对分枝杆菌生理调控功能研究及新型抗结核药物筛选提供基础。     

NETO2 promotes esophageal cancer progression by inducing proliferation and metastasis via PI3K/AKT and ERK pathway

Esophageal squamous cell carcinoma (ESCC) causes aggressive and lethal malignancies with extremely poor prognoses, and accounts for about 90% of cases of esophageal cancer. Neuropilin and tolloid-like 2 (NETO2) protein coding genes have been associated with various human cancers. Nevertheless, little information is reported about the phenotypic expression and its clinical significance in ESCC progression. Here, our study found that NETO2 expression in ESCC patients was associated with tumor clinical stage and lymph node metastasis status. Gain-of-function and loss-of-function analyses showed that NETO2 stimulated ESCC cell proliferation while suppressing apoptosis in vitro and enhanced tumor growth in vivo. Moreover, knockdown of NETO2 significantly inhibited migration and invasion in combination with regulation of epithelial-mesenchymal transition (EMT) related markers. Mechanistically, overexpression of NETO2 increased the phosphorylation of ERK, PI3k/AKT, and Nuclear factor erythroid-2-related factor 2(Nrf2), whereas silencing NETO2 decreased the phosphorylation of these targets. Our data suggest that Nrf2 was a critical downstream event responsible for triggering the PI3K/AKT and ERK signaling pathways and plays a crucial role in NETO2-mediated tumorigenesis. Taken together, NETO2 acts as an oncogene and might serve as a novel therapeutic target or prognostic biomarker in ESCC patients.