Involvement of the ERK1/2 MAPK pathway in insulin-induced S6K1 activation in avian cells

In mammals, insulin regulates S6K1, a key enzyme involved in the control of protein synthesis, via the well-documented phosphoinositide-3'kinase (PI3K) pathway. Conversely, S6K1 is activated by insulin in avian muscle despite the relative insulin insensitivity of the PI3K pathway in this tissue. Mitogen-activated protein kinase (MAPK) cascade is another insulin sensitive pathway. The aim of this study was to explore the potential involvement of the ERK1/2 MAPK pathway in the control of p70 S6 kinase (S6K1) in avian species. Firstly, we characterized ERK1/2 MAPK in various chicken tissues. ERK2 was the only isoform detected in avian species whatever the tissue studied. We also showed that ERK2 is activated in vivo by insulin in chicken muscle. The regulation and the role of ERK2 in insulin signaling were next investigated in chicken hepatoma cells (LMH) and primary myoblasts. Insulin stimulation led to ERK2 and S6K1 phosphorylation, and concomitantly increased kinase activity. U0126, an inhibitor of the ERK MAPK pathway, completely abolished insulin-induced S6K1 phosphorylation and activity in chicken myoblasts, whereas its effect was only partial in LMH cells. In conclusion, these results show that ERK1/2 MAPK is involved in the control of S6K1 by insulin in chicken cells, particularly myoblasts.     

敖汉细毛羊Ⅰ型内根鞘角蛋白基因表达模式的研究分析

[目的]探讨细毛羊毛囊生长期及休止期特异基因的表达模式以及该模式对敖汉细毛羊选育的意义。[方法]通过基因芯片技术对敖汉细毛羊羊毛生长期和休止期的颈部、腹股沟部的上皮基因表达进行检测。[结果]统计分析Ⅰ型内根鞘角蛋白基因KRT25、KRT26、KRT27和KRT28在细毛羊颈部与腹股沟部的表达,发现该基因在细毛羊生长期颈部表达量极显著高于腹股沟部的表达量(差异倍数2,P0.01);对比分析生长期与休止期该基因的表达变化,结果显示在腹股沟部所有芯片涵盖的Ⅰ型内根鞘角蛋白基因的表达都表现出由生长期进入休止期的显著下调(P0.05),除KRT25(LOC443079)外,其他基因的表达变化都在2倍以上。[结论]该研究结果表明Ⅰ型内根鞘角蛋白基因家族的表达与特异部位羊毛密度的控制以及整个毛囊发育生长周期都有着重要的联系。     

Refeeding and insulin activate the AKT/p70S6 kinase pathway without affecting IRS1 tyrosine phosphorylation in chicken muscle

p70 S6 kinase (p70S6K) is a key enzyme involved in the control of protein synthesis. We have previously shown that this kinase is insulin sensitive in chicken muscle despite a relative insulin resistance in the early steps of insulin receptor signaling in this tissue, particularly with no change in tyrosine phosphorylation of the insulin receptor substrate 1 (IRS1). The aim of the present study is to further study the p70S6K pathway in chicken muscle. By analyzing in silico several kinases involved in the protein kinase B (PKB also called AKT)/target of rapamycin (TOR)/p70S6K pathway in the chicken, we showed that the amino acid sequence of the proteins exhibited a very high identity with their homologs in mammalian species and Drosophila. We investigated the regulation of these kinases in vivo or in vitro. Refeeding and insulin treatment significantly (P<0.05) increased the phosphorylation and/or activity of kinases upstream of p70S6K such as AKT and TOR. Similarly, refeeding and insulin increased the phosphorylation of p70S6K on key residues (i.e. T389, T229 and T421/S424) and the phosphorylation of a p70S6K downstream target, the ribosomal protein S6 (by 3-10-fold, P<0.05). Interestingly, we also showed an increase in the phosphorylation level of IRS1 on S632/S635, sites involved in insulin resistance. In conclusion, the AKT/TOR/p70S6K pathway is activated by refeeding and insulin injection, which might negatively regulate IRS1 tyrosine phosphorylation. These results indicate some particularities of the insulin signaling in chicken muscle and suggest the involvement of p70S6K in these features.     

不同加水量对中国白面条品质性状的影响

【目的】加水量是影响面条制作的关键因子,研究其对面条品质的影响对制定标准化面条评价方法提供依据。【方法】试验I选用来自山东和河南的24个小麦品种的面粉,采用3种不同加水量(34%、35%和36%)。试验II选购商业面粉5种,采用5种不同加水量(34%、35%、36%、37%和38%),分别研究不同加水量对中国白面条品质的影响,目的是明确实验室面条制作的最适加水量。【结果】随着加水量的增加,0h鲜面片的亮度L*值显著降低,黄度b*值显著提高。对于品种面粉,当加水量从34%增加到36%时,24h鲜面片的亮度L*值先降低后升高,黄度b*值先升高后降低,红度a*值显著降低;当加水量为35%时,亮度L*值最低,黄度b*值最高。对于商业面粉,当加水量从34%增加到38%时,24h鲜面片的亮度L*值先降低后升高,黄度b*值先升高后降低,红度a*值变化不显著;当加水量为36%时,亮度L*值最低,黄度b*值最高,但加水量对煮熟面条的颜色值和颜色感官评价影响均不显著。随着加水量的增加,面条的硬度、黏弹性、光滑性和总分显著提高,在一定范围内适当增加加水量可以显著改善面条品质。【结论】用软质和混合小麦制作中国白面条的最适加水量为35%,用硬质小麦制作中国白面条的最适加水量为36%。1BL/1RS易位使面粉吸水量增加,持水力降低,导致面团黏性增大,随着加水量的增加,面团发黏现象更为明显,不利于实际操作。对于1BL/1RS易位品种,加水量应在最适加水量的基础上减少1%。商业面粉中国白面条实验室制作的最适加水量为37%。     

miR-33a靶向Lipin1和IRS2调节绵羊前体脂肪细胞分化的研究

旨在揭示miR-33a在绵羊前体脂肪细胞分化中的生物学功能。本研究以15日龄雄性绵羊背部皮下前体脂肪细胞为试验材料,所有的试验均设立3个重复;利用生物信息学软件预测miR-33a的靶基因,并通过双荧光素酶报告试验对预测的潜在靶基因进行验证;用qPCR和Western blotting分别检测miR-33a、Lipin1和IRS2及其编码蛋白的表达,以揭示miR-33a与其靶基因在绵羊前体脂肪细胞分化中的表达规律;慢病毒介导实现miR-33a的过表达和干扰后,检测Lipin1、IRS2和成脂标志基因的表达,并用油红O染色检测脂滴沉积能力,以解析miR-33a对其靶基因的调节机制。生物信息学分析发现,miR-33a与Lipin1和IRS2 3'-UTR都存在结合位点,miR-33a显著下调Lipin1和IRS2野生型双荧光质粒的相对荧光活性（P<0.05）;在绵羊前体脂肪细胞分化中,miR-33a与Lipin1和IRS2的表达趋势相反;过表达miR-33a后,显著下调了Lipin1（P<0.01）和IRS2（P<0.05）及其编码蛋白以及成脂标志基因的表达;干扰miR-33a后,这些基因和蛋白的表达则显著上调;过表达miR-33a减少了脂滴沉积,干扰miR-33a促进了脂滴沉积。在绵羊前体脂肪细胞分化中,miR-33a与Lipin1和IRS2的表达呈负相关。miR-33a靶向Lipin1和IRS2的3'-UTR抑制绵羊前体脂肪细胞分化和脂滴沉积。     

3个不同品种羊Ⅰ型内根鞘角蛋白基因的差异表达

探讨了敖汉细毛羊、小尾寒羊和莱芜黑山羊3个不同品种毛囊生长期与毛囊发育有关的特异基因表达模式。采用基因表达谱芯片技术对上述3个品种羊毛生长期颈部、腹股沟部的Ⅰ型内根鞘角蛋白基因表达进行检测,通过实时定量PCR技术对差异基因进行验证。结果：Ⅰ型内根鞘角蛋白基因家族KRT25、KRT26、KRT27和KRT28在颈部的表达量无品种间显著变化（差异倍数小于2）;而在腹股沟部的表达量在品种间差异极显著（差异倍数大于2,P〈0.01）。实时定量PCR所得结果与基因芯片结果基本吻合。结果表明：Ⅰ型内根鞘角蛋白基因家族在不同品种羊中的表达量与特异部位毛囊分布密度有着重要的关系。     

Kohonen模糊神经网络聚类与数据融合技术在"3S"森林防火中的应用

在简介“3S”系统的基本原理的基础上,进一步介绍了MODIS卫星红外遥感技术对森林防火技术的提升,并对其不足之处提出了Kohonen模糊神经网格聚类技术与“数据融合”技术的改进方法。     

数据融合技术在"3S"森林防火中的应用

本文首先阐明了森林防火对人类实现“可持续发展”战略的重大意义 ;继而在简介“3S” (RS、GIS与GPS)系统的基本原理的基础上 ,进一步介绍了MODIS卫星红外遥感技术对森林防火技术的提升 ,并对其不足之处提出了“数据融合”技术的改进方法 ,最后展望了森林防火工作的未来发展前景。     

基于印度遥感卫星IRS—P6的森林生物量估测模型研究

印度遥感卫星IRS—P6的LISS3数据由于其较高的空间分辨率和相对较低的数据价格而受到广泛关注,而利用LISS3数据估测森林生物量的研究报道较少。以高黎贡山自然保护区常绿阔叶林为研究对象,以2006年印度卫星IRS—P6的LISS3影像为主要数据源,利用地面样地胸径每木调查数据,结合生物量相对生长式,得出样地生物量。通过遥感数据提取4个波段的光谱值、6种植被指数,从DEM获取的海拔、坡度、坡向,共13个遥感及地学因子。在此基础上,提取13个因子的主成分,以前5个主成分值作自变量,建立主成分与地面生物量的回归模型,模型经方差分析及相关性检验,达到显著相关水平,相关系数R=0．7129。     

产生伴胞晶体的芽胞杆菌CTC菌株的16S-23SrRNA间隔区分析

根据能形成伴胞晶体的特征，芽胞杆菌CTC菌株被鉴定为苏云金芽胞杆菌幕虫亚种。但该菌株明显不同于典型的苏云金芽胞杆菌，因为其伴胞晶体蛋白并不是由杀虫晶体蛋白基因编码，而是编码细胞表面S-层蛋白基因的产物，且伴胞晶体蛋白没有检测到对昆虫的毒性。本研究基于对CTC菌株及参照菌的16S-23S rRNA间隔区、编码S-层蛋白的基因进行扩增并测序，从系统发育水平检测到CTC菌株明显与苏云金芽胞杆菌幕虫亚种典型菌株T02存在差异，表明芽胞杆菌CTC菌株更接近蜡状芽胞杆菌。