生态系统基于性状调节的物种间接作用：特征、成因及后果

物种之间的间接作用关系是维持生物群落结构以及生态系统功能的关键因素。目前的理论模型和实验性研究均认为,物种间接作用的传递主要是由物种的密度变化所引起。但大量的实验证据表明,生物个体在形态、生理、行为和生活史性状的适应性变化,是物种间形成间接互作关系的另一个重要机制。生态学家把这种基于物种性状调控的种间关系称为性状调节的间接作用。深入了解性状调节的间接作用类型,发生机制和作用途径,有助于阐释自然界中多物种种间关系的复杂性和多样性形成机制。对性状调节的概念和性状的分类进行系统的总结,指出性状可塑性和物种特异性是物种间性状调节关系形成的两个重要机制。与其他类型的种间互作一样,性状调节的种间作用是驱动物种进化的重要力量。此外,分析了性状调节在自然群落中传递的几个重要途径,并强调这些间接作用在影响和调节生态系统功能和过程中的重要作用。最后,就性状调节种间关系的研究对象、研究尺度、以及研究方法等问题提出若干建议,为今后对这一问题的研究提供相关参考。

“易丰收”对油葵生物产量形成与分配的影响

以盆栽试验研究植物生长调节剂"易丰收"的不同处理方式对油用型向日葵生长发育、物质积累与分配的影响。结果表明:拌种处理对油葵植株的影响最大,株高增高,果盘直径增大,提高单株生物产量及其在各器官中的分配,经济性状均有显著提高;浸种处理对油葵的株高有增高作用,对成熟期生物产量的形成和分配有明显的促进作用,能显著提高油葵的经济性状;开花期喷雾处理对油葵的农艺性状提高作用不明显,对全生育期的物质积累与分配有一定的促进作用,对经济性状的改善效果不大。

Effect of ABA and Biological Bacterial Agents on the Fruit Quality of Jinhua Large and White Peach

[Objective] The aim was to screen the foliar fertilizer and growth regulators to improve the quality of Jinhua Large and White Peach. [Method] The effects of seven foliar fertilizer and growth regulators on the major economic traits of Jinhua Large and White Peach were studied. [Result] After timely spraying of S-ABA and Fushizhuang in young fruit stage,the major economic traits of Large and White Peach including fruit weight and soluble solids content were significantly higher than that of the control,and significantly better than other treatments. In addition,Huoqing spraying treatment could obviously improve the quality of Large and White Peach. [Conclusion] Shifuzhuang,S-ABA and Huoqing spraying could significantly improve the quality of Jinhua Large and White Peach,which were suitable to be disseminated and applied in production.

Acute myeloid leukemia cells inhibit the differentiation and maturation of dendritic cells and induce the generation of regulatory T cells

Objective： To investigate the effects of soluble factors secreted by acute myeloid leukemia （AML） cells on the phenotypical and functional properties of DCs derived from normal mononuclear cells. Methods： Mononuclear cells were cultured with interleukin-4 （IL-4） and granulocyte-macrophage colony-stimulating factor （GM-CSF）, in the presence or absence of 24 h culture supematants from fresh pdmary AML cells, to generate immature DCs. The maturation of DCs was induced by cytokines IL-lbeta, IL-6, tumor necrosis factor-alpha （TNF-alpha）, and prostaglandin-2 （PGE-2）. The phenotypic alterations of DCs and DCs-primed CD4＋ T cells were evaluated using flow cytometry. Precursor frequency （PF） was calculated to monitor the allostimulatory effects of DCs on CD4^＋ and CD8^＋ T cells. Results：AML cell supernatant-treated DCs showed significantly lower expression of co-stimulatory molecules CDS0 and CD86, and reduced response to cytokines IL-1beta, IL-6, TNF-alpha, and PGE-2. The allostimulatory effects of AML cell supematant-treated DCs on CD4^＋ and CD8^＋ T cells were significantly lower than those of normal mature DCs [PF： （1.8 ±0.5）% vs. （5.2 ± 1.6）% for CD4^＋ T cells, （2.1 ±0.6）% vs. （6.5 ± 2.0）% for CD8^＋ T cells, P 〈 0.01]. These AML supernatantoinduced DCs could also induce allogeneic CD4^＋ T cells to differentiate into CD4^＋CD25high T cells, which had immunophenotyping characteristics of regulatory T cells, i.e. they expressed Foxp3 but not active maker CD69. Conclusion： This study demonstrates that soluble factors secreted by AML cells can inhibit development and functions of DCs. In addition, AML supernatant-induced DCs can induce the generation of CD4^＋CD25^high T cells from CD4^＋ T cells, which may be a mechanism of increased prevalence of CD4^＋CD25^high regulatory T cells and immune dysfunction in AML patients.

Characterization of the Xenopus homolog of animmediate early gene associated with cell activation: sequence analysis and regulation of its expression by thyroid hormone during amphibian metamorphosis

The complex transformation of a tadpole to a frogduring amphibian development is under the control of thyroid hormone (T3). T3 is known to regulate gene transcription through its nuclear receptors. We have previouslyisolated many genes which are up-regulated by T3 in theintestine of Xenopus laevis tadpoles. We have now cloneda full- length cDNA for one such gene (IU12). Sequenceanalysis shows that the IU12 cDNA encodes a plasmamembrane protein with 12 transmembrane domains andhomologous to a mammalian gene associated with cell activation and organ development. Similarly, we have foundthat IU12 is activated during intestinal remodeling whenboth cell death and proliferation take place. Furthermore,IU12 is an early T3-response gene and its expression in theintestine during T3-induced metamorphosis mimics thatduring normal development. These results argue for a roleof IU12 in the signal transduction pathways leading to intestinal metamorphosis.

Development of Elementary School Teachers＇ Self-Regulated Learning Exploratory Factor Scale

Self-regulated learning （SRL） is one of the precious ways in teachers＇ professional development, and its operation level includes different factors. With studies abroad and our preliminary investigation as base, this study developed a scale to test the factors SRL includes. According to the result of 905 teachers working in elementary school by exploratory factor analysis, the SRL for elementary teachers is consisted of its sociality （it included selecting leads and seeking for instructing）, its motivation（it included self-improvement and self-excelling）, its methods（it included strategy use and habitual behavior）, and its outcomes（it included extensive reading and teachers＇ professional development）. All the result indicated Teachers＇ SRL Scale had clear factor structure, good reliability and validity. It can be used to test the current operating situation of SRL for teachers working in elementary school.