具有解硅功能微生物的应用研究

解硅微生物能分解硅酸盐和铝硅酸盐矿物,可使硅变成可溶物,采用微生物活化降解矿物质硅,可以实现环保生态型无害化处理和资源化利用,具有很高的经济价值和生态价值。综述了解硅功能微生物的应用领域、解硅机理以及影响因素,并对今后的研究方向进行了展望。     

有效微生物解磷工艺研究

采用单因素试验和正交试验对有效微生物解磷工艺进行了研究,得出最佳的解磷条件是,发酵时间为96h,发酵温度为34℃,尾矿粉加入量为3g,在此条件下测得溶磷量为14.12g/kg。有效微生物用于生产生物磷肥,可解决磷矿企业环境污染问题,同时为农业生产提供肥料,减少农业生产成本。     

Structural basis of RNA-dependent recruitment of glutamine to the genetic code

Glutaminyl-transfer RNA (Gln-tRNA(Gln)) in archaea is synthesized in a pretranslational amidation of misacylated Glu-tRNA(Gln) by the heterodimeric Glu-tRNA(Gln) amidotransferase GatDE. Here we report the crystal structure of the Methanothermobacter thermautotrophicus GatDE complexed to tRNA(Gln) at 3.15 angstroms resolution. Biochemical analysis of GatDE and of tRNA(Gln) mutants characterized the catalytic centers for the enzyme's three reactions (glutaminase, kinase, and amidotransferase activity). A 40 angstrom-long channel for ammonia transport connects the active sites in GatD and GatE. tRNA(Gln) recognition by indirect readout based on shape complementarity of the D loop suggests an early anticodon-independent RNA-based mechanism for adding glutamine to the genetic code.     

Coactivation of receptor tyrosine kinases affects the response of tumor cells to targeted therapies

Targeted therapies that inhibit receptor tyrosine kinases (RTKs) and the downstream phosphatidylinositol 3-kinase (PI3K) signaling pathway have shown promising anticancer activity, but their efficacy in the brain tumor glioblastoma multiforme (GBM) and other solid tumors has been modest. We hypothesized that multiple RTKs are coactivated in these tumors and that redundant inputs drive and maintain downstream signaling, thereby limiting the efficacy of therapies targeting single RTKs. Tumor cell lines, xenotransplants, and primary tumors indeed show multiple concomitantly activated RTKs. Combinations of RTK inhibitors and/or RNA interference, but not single agents, decreased signaling, cell survival, and anchorage-independent growth even in glioma cells deficient in PTEN, a frequently inactivated inhibitor of PI3K. Thus, effective GBM therapy may require combined regimens targeting multiple RTKs.     

Therapy-induced acute recruitment of circulating endothelial progenitor cells to tumors

The contribution of bone marrow-derived circulating endothelial progenitor cells (CEPs) to tumor angiogenesis has been controversial, primarily because of their low numbers in blood vessels of untreated tumors. We show that treatment of tumor-bearing mice with vascular disrupting agents (VDAs) leads to an acute mobilization of CEPs, which home to the viable tumor rim that characteristically remains after such therapy. Disruption of this CEP spike by antiangiogenic drugs or by genetic manipulation resulted in marked reductions in tumor rim size and blood flow as well as enhanced VDA antitumor activity. These findings also provide a mechanistic rationale for the enhanced efficacy of VDAs when combined with antiangiogenic drugs.     

基于双线性映射的植物叶片校正算法的研究

针对在应用数码相机采集大田作物叶片图像时出现的植物叶片图像倾斜和几何失真等问题,提出了基于双线性映射的植物叶片校正算法.测量有效性不受叶片大小、形状差异和叶片图像中叶片周边白色背景的影响.实验验证该方法校正叶片图像,精度可达99%以上,是进一步提取植物叶面特征的基础.     

基于遗传神经网络的植物叶片病害特征提取的研究

为提高作物病害定量、快速、准确识别,以大豆褐斑病为例,综合运用计算机数字图像处理技术与人工神经网络技术,建立了一个多层前馈遗传神经网络,实现了大豆褐斑病的识别与特征计算。本技术首先通过计算机视觉技术采集叶片图像,尔后,采用遗传神经网络完成了对病斑图像的识别,最后运用数字图像处理技术完成了对病斑区域相关特征值的计算,实验识别准确率达100%。     

Antibodies to Asp-Asp-Glu-Asp can inhibit transport of nuclear proteins into the nucleus

The signal sequence of simian virus 40 (SV40) large T-antigen for translocation into the nucleus is composed of positively charged amino acids Lys-Lys-Lys-Arg-Lys. Rabbit antibodies to a synthetic peptide containing the negatively charged amino acid sequence Asp-Asp-Asp-Glu-Asp were obtained. Indirect immunofluorescence of the antigens recognized by the antibody was punctate at the nuclear rim or the nuclear surface, depending on the plane of focus. The antibody blocked transport of nuclear proteins into the nucleus. The antigens recognized by the antibody were predominantly localized to the nuclear pores.     

Coupling of stress in the ER to activation of JNK protein kinases by transmembrane protein kinase IRE1

Malfolded proteins in the endoplasmic reticulum (ER) induce cellular stress and activate c-Jun amino-terminal kinases (JNKs or SAPKs). Mammalian homologs of yeast IRE1, which activate chaperone genes in response to ER stress, also activated JNK, and IRE1alpha-/- fibroblasts were impaired in JNK activation by ER stress. The cytoplasmic part of IRE1 bound TRAF2, an adaptor protein that couples plasma membrane receptors to JNK activation. Dominant-negative TRAF2 inhibited activation of JNK by IRE1. Activation of JNK by endogenous signals initiated in the ER proceeds by a pathway similar to that initiated by cell surface receptors in response to extracellular signals.     

The intracellular fate of Salmonella depends on the recruitment of kinesin

Salmonella enterica causes a variety of diseases, including gastroenteritis and typhoid fever. The success of this pathogen depends on its capacity to proliferate within host cells in a membrane-bound compartment. We found that the Salmonella-containing vacuole recruited the plus-end-directed motor kinesin. Bacterial effector proteins translocated into the host cell by a type III secretion system antagonistically regulated this event. Among these effectors, SifA targeted SKIP, a host protein that down-regulated the recruitment of kinesin on the bacterial vacuole and, in turn, controlled vacuolar membrane dynamics.     

Inhibition of cellular proliferation by antisense oligodeoxynucleotides to PCNA cyclin

The proliferating cell nuclear antigen (PCNA or cyclin) is a nuclear protein recently identified as a cofactor of DNA polymerase delta. When exponentially growing Balb/c3T3 cells are exposed to antisense oligodeoxynucleotides to PCNA, both DNA synthesis and mitosis are completely suppressed. A corresponding sense oligodeoxynucleotide has no inhibitory effects. These experiments indicate that PCNA (cyclin) is important in cellular DNA synthesis and in cell cycle progression.     

山羊胎儿成纤维细胞转染人t-PA指形区缺失基因及其核移植研究

采用阳离子脂质体法将人t-PA指形区缺失基因乳腺特异性表达载体(pEBT)导入山羊胎儿成纤维细胞,以山羊胎儿成纤维细胞和转染的山羊胎儿成纤维细胞作供体,构建核移植胚,对其体外发育情况进行了研究,比较了2种供体细胞(山羊胎儿成纤维细胞和转人t-PA指形区缺失基因的山羊胎儿成纤维细胞)及转人t-PA指形区缺失基因的山羊胎儿成纤维细胞饥饿处理与否对核移植胚胎体外发育的影响。结果表明,早期核移植胚有荧光蛋白(GFP)的表达;以山羊胎儿成纤维细胞作供体细胞时,核移植胚的桑葚胚率(50.3%)及囊胚率(16.0%)均高于以转人t-PA指形区缺失基因胎儿成纤维细胞为供体时的桑葚胚率(48.4%)和囊胚率(10.9%),但差异不显著(P>0.05);转人t-PA指形区缺失基因的山羊胎儿成纤维细胞经饥饿处理后,其核移植胚胎的卵裂率(73.6%)与不饥饿时的卵裂率(73.9%)差异不显著;饥饿处理后核移植胚胎的桑葚胚率(48.5%)和囊胚率(11.2%)均高于不饥饿处理的桑葚胚率(39.2%)和囊胚率(9.2%),但差异不显著(P>0.05)。本研究成功地构建了转人t-PA指形区缺失基因的体细胞核移植胚胎,体外囊胚率为11.2%。     

钙依赖蛋白激酶与植物钙离子的信号转导

钙离子所依赖的蛋白激酶(CDPKs)在植物钙信号转导过程中发挥着关键作用。本文就CDPK的结构以及生物学功能等方面做了较为详尽的阐述。     

Photosynthetic properties of the mid-vein and leaf lamina of field-grown,high-yield hybrid rice during senescence

Previous studies with rice(Oryza sativa L.) have shown that the different components of the photosynthetic apparatus are not uniformly synthesized or degraded during senescence. However, while most of those studies have focused on the leaf lamina, few have addressed senescence-associated chloroplast function or leaf physiology. Here, we investigated the photosynthetic properties of the mid-vein and leaf lamina in a high-yield hybrid rice cultivar(Liangyoupei 9, LYP9) during the senescence stage....