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971.
972.
Weiwei Wen Kun Li Saleh Alseekh Nooshin Omranian Lijun Zhao Yang Zhou Yingjie Xiao Min Jin Ning Yang Haijun Liu Alexandra Florian Wenqiang Li Qingchun Pan Zoran Nikoloski Jianbing Yan Alisdair R. Fernie 《The Plant cell》2015,27(7):1839-1856
Deciphering the influence of genetics on primary metabolism in plants will provide insights useful for genetic improvement and enhance our fundamental understanding of plant growth and development. Although maize (Zea mays) is a major crop for food and feed worldwide, the genetic architecture of its primary metabolism is largely unknown. Here, we use high-density linkage mapping to dissect large-scale metabolic traits measured in three different tissues (leaf at seedling stage, leaf at reproductive stage, and kernel at 15 d after pollination [DAP]) of a maize recombinant inbred line population. We identify 297 quantitative trait loci (QTLs) with moderate (86.2% of the mapped QTL, R2 = 2.4 to 15%) to major effects (13.8% of the mapped QTL, R2 >15%) for 79 primary metabolites across three tissues. Pairwise epistatic interactions between these identified loci are detected for more than 25.9% metabolites explaining 6.6% of the phenotypic variance on average (ranging between 1.7 and 16.6%), which implies that epistasis may play an important role for some metabolites. Key candidate genes are highlighted and mapped to carbohydrate metabolism, the tricarboxylic acid cycle, and several important amino acid biosynthetic and catabolic pathways, with two of them being further validated using candidate gene association and expression profiling analysis. Our results reveal a metabolite-metabolite-agronomic trait network that, together with the genetic determinants of maize primary metabolism identified herein, promotes efficient utilization of metabolites in maize improvement. 相似文献
973.
Kan Chen Wanlu Cao Juan Li Dave Sprengers Pratika Y Hernanda Xiangdong Kong Luc JW van der Laan Kwan Man Jaap Kwekkeboom Herold J Metselaar Maikel P Peppelenbosch Qiuwei Pan 《Molecular medicine (Cambridge, Mass.)》2015,21(1):792-802
As uncontrolled cell proliferation requires nucleotide biosynthesis, inhibiting enzymes that mediate nucleotide biosynthesis constitutes a rational approach to the management of oncological diseases. In practice, however, results of this strategy are mixed and thus elucidation of the mechanisms by which cancer cells evade the effect of nucleotide biosynthesis restriction is urgently needed. Here we explored the notion that intrinsic differences in cancer cell cycle velocity are important in the resistance toward inhibition of inosine monophosphate dehydrogenase (IMPDH) by mycophenolic acid (MPA). In short-term experiments, MPA treatment of fast-growing cancer cells effectively elicited G0/G1 arrest and provoked apoptosis, thus inhibiting cell proliferation and colony formation. Forced expression of a mutated IMPDH2, lacking a binding site for MPA but retaining enzymatic activity, resulted in complete resistance of cancer cells to MPA. In nude mice subcutaneously engrafted with HeLa cells, MPA moderately delayed tumor formation by inhibiting cell proliferation and inducing apoptosis. Importantly, we developed a lentiviral vector–based Tet-on label-retaining system that enables to identify, isolate and functionally characterize slow-cycling or so-called label-retaining cells (LRCs) in vitro and in vivo. We surprisingly found the presence of LRCs in fast-growing tumors. LRCs were superior in colony formation, tumor initiation and resistance to MPA as compared with fast-cycling cells. Thus, the slow-cycling compartment of cancer seems predominantly responsible for resistance to MPA. 相似文献
974.
Biotoxicity of individual metals is well investigated but that of metal mixture, an environmental reality, in the developing metal mixture, is relatively obscure. Experimental evidences had shown that this mixture could give rise to combined effects that were different from the effect of metals one by one. This review provides an overview of recent research on metal mixture toxicity and the methods employed to predict their toxic combined effects. The two established reference models, the concentration-addition model and the independent-addition model, were used for evaluating the combined effect from the biological activities of the metal mixtures. While the reference models had provided reasonable tools for analyzing the combined effects, the actual predictions for binary metal mixtures showed often somewhat less than additive combined effects compared to what has been observed. As the metal bioavailability is oriented by several environmental factors as well as the toxicodynamics of metals is highly compound-specific, the non-interactive combined effects may be confused with different processes of the interactions. Thus, for improving the predictability of combined effects in metal mixture toxicity, numerous qualitative and quantitative analysis are required for the processes governing the toxicokinetics and dynamics of metals in aquatic organisms. 相似文献
975.
Jie Zhang Qixiang Zhang Tangren Cheng Weiru Yang Huitang Pan Junjun Zhong Long Huang Enze Liu 《DNA research》2015,22(3):183-191
High-density genetic map is a valuable tool for fine mapping locus controlling a specific trait especially for perennial woody plants. In this study, we firstly constructed a high-density genetic map of mei (Prunus mume) using SLAF markers, developed by specific locus amplified fragment sequencing (SLAF-seq). The linkage map contains 8,007 markers, with a mean marker distance of 0.195 cM, making it the densest genetic map for the genus Prunus. Though weeping trees are used worldwide as landscape plants, little is known about weeping controlling gene(s) (Pl). To test the utility of the high-density genetic map, we did fine-scale mapping of this important ornamental trait. In total, three statistic methods were performed progressively based on the result of inheritance analysis. Quantitative trait loci (QTL) analysis initially revealed that a locus on linkage group 7 was strongly responsible for weeping trait. Mutmap-like strategy and extreme linkage analysis were then applied to fine map this locus within 1.14 cM. Bioinformatics analysis of the locus identified some candidate genes. The successful localization of weeping trait strongly indicates that the high-density map constructed using SLAF markers is a worthy reference for mapping important traits for woody plants. 相似文献
976.
977.
978.
The mechanism by which prokaryotic cells organize and segregate their intracellular organelles during cell division has recently been the subject of substantial interest. Unlike other microorganisms, magnetotactic bacteria (MTB) form internal magnets (known as magnetosome chain) for magnetic orientation, and thus face an additional challenge of dividing and equipartitioning this magnetic receptor to their daughter cells. Although MTB have been investigated more than four decades, it is only recently that the basic mechanism of how MTB divide and segregate their magnetic organelles has been addressed. In this issue of Molecular Microbiology, the cell cycle of the model magnetotactic bacterium, Magnetospirillum gryphiswaldense is characterized by Katzmann and co-workers. The authors have found that M. gryphiswaldense undergoes an asymmetric cell division along two planes. A novel wedge-like type of cellular constriction is observed before separation of daughter cells and magnetosome chains, which is assumed to help cell cope with the magnetic force within the magnetosome chain. The data shows that the magnetosome chain becomes actively recruited to the cellular division site, in agreement with the previous suggestions described by Staniland et al. (2010), and the actin-like protein MamK is likely involved in this fast polar-to-midcell translocalization. With the use of cryo-electron tomography, an arc-shaped Z ring is observed near the division site, which is assumed to trigger the asymmetric septation of cell and magnetosome chain. 相似文献
979.
980.
Ding Ding Huang Peng Pan Ying-Qiu Chen Shu-Qing 《World journal of microbiology & biotechnology》2011,27(12):2957-2967
In China, staphylococcin injection has been commonly used in the combined treatment of cancer to enhance the systemic immune
response and reduce the toxicities associated with chemotherapy and radiation therapy. It is claimed that the main active
component in the injection is staphylococcal enterotoxin C2 (SEC2). To determine whether other serological types of staphylococcal
enterotoxins (SEs) could also be present in the injection products, in this study, the distribution of se genes (from sea to see, from seg to seu) in the one and only production strain of Staphylococcus aureus from one manufacturing company was analyzed by PCR method. In addition, sek and seq genes were cloned from the strain and the corresponding recombinant proteins, rSEK and rSEQ, were expressed in Escherichia coli and purified by affinity chromatography and anion-exchange chromatography. The superantigenic properties of the two recombinant
proteins were then measured by MTT method. The PCR results showed that seven se genes are harbored by the production strain. However, sec2 gene was not detected. The results of MTT assay showed that rSEK and rSEQ could elicit strong stimulatory effects on proliferation
and cytotoxicity of murine splenocytes in vitro. Overall, the results in this study indicated that one or a plurality of the
seven SEs may be present in the related products, and that the two recombinant SEs are promising candidates as immunomodulatory
agents for cancer therapy. 相似文献