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The paper does the correlevant analysis on the partial macroeconomic indicators and the commercial network index of the county-level cities, based on the survey data of the county-level cities’ commercial network in Jiujiang. The data analysis shows that there are some correlations between the commercial network index of the county-level cities and some macroeconomic indicators, which lays the theoretical foundation for the further research. Keywords— county-level cities, commercial network Present Situation, exploratory research 九江市县级城市商业网点现状探索性研究 姚盛辉 1 谢丽芬 2 1) 九江学院电子商务学院市场营销教研室,中国 2) 九江学院经济与管理学院国际贸易教研室,中国 摘 要 本文以九江市县级城市商业网点的调查数据为基础,对县级城市部分宏观经济指标与县级城市商业网点指标进行了相关 分析研究。通过对数据研究分析表明,县级城市商业网点与部分宏观经济指标间确实存在一定的相关性,为进一步进行分析研究奠定 了理论基础。 关键词 县级城市,商业网点现状,探索性研究 1.引言 县级城市是我国城市体系中的初级城市,是连接地级 城市和农村乡镇的重要纽带,总结县级城市商业网点现状 规律,对今后开展县级城市商业网点规划相关工作起到理 论参考作用。当前国内外关于城市商业网点的研究文献, 大都集中在大型城市商业网点规划方向,对县级城市商业 网点发展现状的研究较少,而进一步研究到县级城市商业 网点与经济对应关系的理论成果更是少之又少,本文旨在 探究县级城市商业网点现状与经济发展相关性的一般规 律,从而丰富了县级城市商业网点研究的理论成果,为县 级城市商业经济发展提供理论基础。 2.城市商业网点研究述评 国内关于商业网点为主题的研究主要参考克利斯泰勒 (1933)提出的“中心地理论”思想,虽然现实中克利斯 泰勒提出的假设条件很难满足,但不可否认其在区域规划 中,可以起到合理地布局区域的公共服务设施和其它经济 和社会职能的指导作用。除了克利斯泰勒的“中心地理论” 外,还有德国地理学家沃尔特克里斯(1933)、廖什、泰勒 (1939)创立的区位理论;麦肯齐(1933)、哈里斯和乌尔 曼(1945)创立的“城市多核理论”;英国经济学家刘易斯 (1954)阐述的“二元经济结构”等一系列的经典理论, 形成了投入产出模型、线性规划模型、区域空间均衡模型、 区域经济增长模型、环境影响模型、动态城市模型、城市 体系的一般均衡模型、分散化的城市理论模型等等。而布 赖恩•贝里(1973)用数理统计方法对中心地学说进行了许 多实证性研究,成为了城市系统研究的一个重要转折点, 他把城市人口分布与服务中心的等级联系起来,为此后的 学者开始从研究城市零售商业的空间布局规律提供了更加 微观的视角。 国外对城市商业网点的研究与实践工作开展已有近百 年的历史,经历了从宏观到微观的发展过程,,值得我们借 International Conference on Applied Social Science Research (ICASSR 2015) © 2016. The authors Published by Atlantis Press 991 鉴学习。但是,我国幅员辽阔特别是区域间的经济发展不 均衡,要求我们要结合具体区域经济特征对研究对象开展 科学的、有针对的分析,这样才能更好地指导商业网点规 划的实践工作。方元平(2007)撰文指出:虽然国内城市 商业区位研究已取得显著成就,但与国外比较,还存在中观 层面和微观层面的研究关注不足,研究不够系统,缺少相对 应理论研究。[8] 3.城市商业网点现状研究方法 带领 12批次 120人次对九江市 9个县级城市城区规划 范围内的商业网点布局情况进行了全面调查;并实地走访 了 9 个县级城市的多个政府事业行政单位,获取相关城市 的统计数据和资料,完全掌握 9 个县级城市商业网点现状 数据。整理各个县级城市社会经济指标,分析了近五年的 各个县级城市的经济环境,通过现有的县级城市商业网点 数据,从商业网点总数量、网点营业面积和从业人员数量 三个方面描述,展示各个县级城市的商业网点发展现状。 在完成九江市 9 个县级城市(星子县、湖口县、德安县、 共青城市、彭泽县、都昌县、永修县、武宁县、修水县) 商业网点现状调查的基础上,对九江市 9 个县级城市商业 网点现状进行研究和分析,对城市商业网点业态结构和网 点数量现状描述(因具体原因数据没有公开),并在此基础 上,结合各个城市的经济发展水平进行分析。 根据各个县级城市的经济指标和商业网点指标,运用 双相关方法,应用 SPSS20.0 软件,进行数据分析,探寻经 济数据与网点数据之间的相关性。商业发展指标以商业网 点数量、面积和从业人员数量三个方面进行分析;社会经 济指标以 GDP、城区人口等经济数据入手进行分析。

In most flowering plant species, pollination and fertilization occur during the hot summer, so plants must have evolved a mechanism that ensures normal growth of their pollen tubes at high temperatures. Despite its importance to plant reproduction, little is known about the molecular basis of thermotolerance in pollen tubes. Here we report the identification and characterization of a novel Arabidopsis gene, Thermosensitive Male Sterile 1 (TMS1), which plays an important role in thermotolerance of pollen tubes. TMS1 encodes a Hsp40-homologous protein with a DnaJ domain and an a_ERdj5_C domain found in protein disulfide isomerases (PDI). Purified TMS1 expressed in Escherichia coli (BL21 DE3) had the reductive activity of PDI. TMS1 was expressed in pollen grains, pollen tubes and other vegetative tissues, including leaves, stems and roots. Heat shock treatment at 37 degrees C increased its expression levels in growing pollen tubes as well as in vegetative tissues. A knockout mutation in TMS1 grown at 30 degrees C had greatly retarded pollen tube growth in the transmitting tract, resulting in a significant reduction in male fertility. Our study suggests that TMS1 is required for thermotolerance of pollen tubes in Arabidopsis, possibly by functioning as a co-molecular chaperone.

In flowering plants, penetration of the pollen tube through stigma, style, and transmitting tract is essential for delivery of sperm nuclei to the egg cells embedded deeply within female tissues. Despite its importance in plant reproduction, little is known about the underlying molecular mechanisms that regulate the navigation of the pollen tube through the stigma, style, and transmitting tract. Here, we report the identification and characterization of an Arabidopsis thaliana gene, VANGUARD1 (VGD1) that encodes a pectin methylesterase (PME)-homologous protein of 595 amino acids and is required for enhancing the growth of pollen tubes in the style and transmitting tract tissues. VGD1 was expressed specifically in pollen grain and the pollen tube. The VGD1 protein was distributed throughout the pollen grain and pollen tube, including the plasma membrane and cell wall. Functional interruption of VGD1 reduced PME activity in the pollen to 82% of the wild type and greatly retarded the growth of the pollen tube in the style and transmitting tract, resulting in a significant reduction of male fertility. In addition, the vgd1 pollen tubes were unstable and burst more frequently when germinated and grown on in vitro culture medium, compared with wild-type pollen tubes. Our study suggests that the VGD1 product is required for growth of the pollen tube, possibly via modifying the cell wall and enhancing the interaction of the pollen tube with the female style and transmitting tract tissues.

In flowering plants, pollen formation depends on the differentiation and interaction of two cell types in the anther: the reproductive cells, called microsporocytes, and somatic cells that form the tapetum. The microsporocytes generate microspores, whereas the tapetal cells support the development of microspores into mature pollen grains. Despite their importance to plant reproduction, little is known about the underlying genetic mechanisms that regulate the differentiation and interaction of these highly specialized cells in the anther. Here, we report the identification and characterization of a novel TAPETUM DETERMINANT1 (TPD1) gene that is required for the specialization of tapetal cells in the Arabidopsis anther. Analysis of the male-sterile mutant, tpd1, showed that functional interruption of TPD1 caused the precursors of tapetal cells to differentiate and develop into microsporocytes instead of tapetum. As a results, extra microsporocytes were formed and tapetum was absent in developing tpd1 anthers. Molecular cloning of TPD1 revealed that it encodes a small protein of 176 amino acids. In addition, tpd1 was phenotypically similar to excess microsporocytes1/extra sporogenous cells (ems1/exs) single and tpd1 ems1/exs double mutants. These data suggest that the TPD1 product plays an important role in the differentiation of tapetal cells, possibly in coordination with the EMS1/EXS gene product, a Leu-rich repeat receptor protein kinase.

Previously, we reported that the TAPETUM DETERMINANT1 (TPD1) gene is required for specialization of tapetal cells in the Arabidopsis (Arabidopsis thaliana) anther. The tpd1 mutant is phenotypically identical to the excess microsporocytes1 (ems1)/extra sporogenous cells (exs) mutant. The TPD1 and EMS1/EXS genes may function in the same developmental pathway in the Arabidopsis anther. Here, we further report that overexpression of TPD1 alters the cell fates in the Arabidopsis carpel and tapetum. When TPD1 was expressed ectopically in the wild-type Arabidopsis carpel, the number of cells in the carpel increased significantly, showing that the ectopic expression of TPD1 protein could activate the cell division in the carpel. Furthermore, the genetic analysis showed that the activation of cell division in the transgenic carpel by TPD1 was dependent on EMS1/EXS, as it did not happen in the ems1/exs mutant. This result further suggests that TPD1 regulates cell fates in coordination with EMS1/EXS. Moreover, overexpression of TPD1 in tapetal cells also delayed the degeneration of tapetum. The TPD1 may function not only in the specialization of tapetal cells but also in the maintenance of tapetal cell fate.

The plant life cycle involves an alternation of generations between sporophyte and gametophyte. Currently, the genes and pathways involved in gametophytic development and function in flowering plants remain largely unknown. A large-scale mutant screen of Ds transposon insertion lines was employed to identify 130 mutants of Arabidopsis thaliana with defects in female gametophyte development and function. A wide variety of mutant phenotypes were observed, ranging from defects in different stages of early embryo sac development to mutants with apparently normal embryo sacs, but exhibiting defects in processes such as pollen tube guidance, fertilization or early embryo development. Unexpectedly, nearly half of the mutants isolated in this study were found to be primarily defective in post-fertilization processes dependent on the maternal allele, suggesting that genes expressed from the female gametophyte or the maternal genome play a major role in the early development of plant embryos. Sequence identification of the genes disrupted in the mutants revealed genes involved in protein degradation, cell death, signal transduction and transcriptional regulation required for embryo sac development, fertilization and early embryogenesis. These results provide a first comprehensive overview of the genes and gene products involved in female gametophyte development and function within a flowering plant.