围栏封育对退化灌丛草地群落土壤特性和植被的影响

以雅鲁藏布江中游半干旱河谷山地灌丛草地群落为研究对象,采用野外调查和室内试验结合的方法,研究了围栏封育对灌丛草地植被及土壤养分含量的影响,以期为有效修复雅鲁藏布江中游河谷山地植被退化提供科学参考。结果表明:围栏封育3年土壤有机质、全磷、速效磷、速效钾含量均高于围栏外,土壤表层(0～10cm)养分含量增加显著(P<0.05),随着土壤深度的增加,土壤养分含量与围栏外逐渐趋于一致,至30～40cm到达相同水平;围栏封育后灌丛草地群落高度和产量显著增加(P<0.05),分别比围栏外增加了74%和101%,高度、产量增加主要是由禾本科和莎草科引起;围栏封育对群落组成和物种重要值产生不同程度的影响,主要表现为生物多样性增加,禾本科、莎草科等适口性好的物种重要值增加,杂草类不可食物种重要值相对下降;Rarefaction曲线法结果显示,围栏内物种多样性大于围栏外,与传统多样性指数方法结果一致。     

Metformin sensitizes human breast cancer MDA-MB-231 cells to tamo-xifen through down-regulation of c-Myc

AIM: To investigate whether metformin enhances the sensitivity of human breast cancer MDA-MB-231 cells to tamoxifen by down-regulating c-Myc. METHODS: The cell viability, colony formation, apoptosis, and migration and invasion abilities of MDA-MB-231 cells were detected by CCK-8 assay, colony formation experiment, flow cytometry and Transwell assay. The expression level of c-Myc was quantified by Western blot and immunohistochemical analysis. The antitumor effects of metformin and tamoxifen were investigated in vivo in a MDA-MB-231 triple-negative breast cancer xenograft model in the SCID mice. RESULTS: Metformin in combination with tamoxifen exerted synergistic effects on inhibition of the viability, colony formation, migration and invasion, and induced the apoptosis compared with the controls and either agent treatment alone in the MDA-MB-231 cells. The levels of c-Myc was down-regulated in vitro by treatment with metformin and/or tamoxifen (P<0.01). Moreover, metformin or in combination with tamoxifen also reduced the growth of MDA-MB-231 breast cancer tumors in the SCID mice by down-regulation of c-Myc in vivo. CONCLUSION: Metformin in combination with tamoxifen exerts synergistic effects on inhibition of the proliferation, migration, invasion and tumor growth of human triple-negative breast cancer MDA-MB-231 cells by down-regulating c-Myc expression, suggesting that metformin in combination with tamoxifen merits further evaluation as a target.     

苹果园春季土施尿素的利用及其在土壤中的累积

 以7年生嘎拉苹果/平邑甜茶为试材, 利用¹⁵N示踪技术, 研究了苹果生产体系中氮素年周期 的利用、残留、损失及在土壤中的迁移动态。结果表明, 对春季土施尿素的利用率盛花期较低, 为11.38% , 至采收后达到最高。土壤氮素残留率盛花期最高, 为57.10% , 果实采后残留率最低。年周期中各土层氮素残留量不同, 盛花期20～40 cm土层残留量最高, 采收后最低, 0～20 cm土层在新梢旺长期残留量最高, 果实成熟期最低, 而40～60 cm土层在果实膨大期残留量达到最高, 在采收后0～20 cm土层残留有所增加, 其余各土层残留量均达到最低值。氮素损失与土壤残留呈相反的变化趋势, 氮素损失率在盛花期最低为31.53% , 随物候期的推迟逐渐升高, 在果实采后高达58.40%     

红壤甜橙园土壤和叶片营养元素相关性分析

 于2010 年和2011 年在江西省安远县和寻乌县这两大赣南甜橙生产县,共采集181 个红壤枳 砧甜橙园的土壤样品和叶片样品,进行营养元素含量测定,并对土壤和叶片相应营养元素含量进行相关 性分析,为评价测土配方施肥是否适宜红壤甜橙园提供依据。结果表明：土壤碱解氮、交换性钙、交换 性镁、有效铁和有效锌的丰缺状况在甜橙叶片对应营养元素丰缺水平上能得到一定程度的反映;土壤有 效钾、有效磷、有效铜和有效硼的状况则难以在甜橙叶片对应营养元素丰缺水平上得到反映。相关性分 析结果显示,只有2010 年安远县甜橙园土壤有效Zn 含量与叶片Zn 含量呈显著正相关（P < 0.05）,其余 土壤有效营养元素含量与叶片对应营养元素含量之间均无显著相关性。表明测土配方施肥不适宜红壤甜 橙园,建议实行以叶片营养诊断为主、土壤诊断为辅的配方施肥策略。     

马铃薯脱毒组培快繁技术与实践

病毒病是为害马铃薯生长的主要病害之一,长期的无性繁育,使病毒长期积累,导致马铃薯世代带毒繁育,严重影响了马铃薯的品种特性。在了解马铃薯病毒病的基础上,采用热处理加茎尖培养的方式获得马铃薯脱毒苗;在此基础上,利用植物组织培养技术,在一定时间内繁育生产所需种苗,并通过炼苗、移栽等环节,建立马铃薯脱毒种苗繁育体系,从而获得脱毒马铃薯良种。     

茉莉酸甲酯对葡萄植株不定根发育的影响

利用不同浓度的茉莉酸甲酯（MeJA）对葡萄组培植株进行处理,进而分析其生理及基因表达变化,结果表明MeJA能抑制植株不定根的分化和伸长,诱导根、茎、叶组织中的脱落酸（ABA）含量升高,但降低赤霉素（GA）、生长素（IAA）和细胞分裂素（ZR）的含量,且影响叶片中叶绿素代谢导致褪绿黄化。MeJA能诱导植物体内茉莉酸合成代谢基因表达进而提高内源茉莉酸的含量,诱导ABA合成代谢和信号路径中的基因表达,但是会抑制生长素、赤霉素、细胞分裂素、油菜素内酯合成代谢基因的表达,抑制了与根发育和延伸相关基因VvXET、VvEXPB2、VvEXPA7和VvWUS的表达,进而抑制不定根的发生,导致植物发育缓慢。因此,MeJA通过影响其他激素的合成代谢来调控它们在植物中的含量,导致内源激素不平衡影响植株发育,并调控植株根的发育状态,在不定根发育方面起负向调控作用。     

SPAD计在黄瓜氮素营养诊断中的应用效果

在日光温室内,采用小区种植的方式应用叶绿素仪SPAD-502和硝态氮反射仪快速监测黄瓜叶片氮素营养的研究。结果表明:黄瓜正在开花叶片和正在结果叶片的全氮含量均与黄瓜叶片的SPAD值和硝态氮的浓度具有很好的相关性,无论花叶还是果叶都是开展氮素营养诊断的主要部位;基于SPAD计的无损诊断结合硝态氮的快速诊断可以获取氮素营养状况,生产中根据条件作出正确的选择,实施合理施肥。     

豚草发生地土壤微生物的数量特征

豚草是世界性的恶性害草,造成巨大的农牧业损失和景观破坏.该文研究了豚草发生地土壤微生物的数量特征.结果表明:土壤微生物总数的峰值出现在8月,放线菌、细菌和真菌的数量峰值分别出现在7～9月.在8月和9月,豚草样地的土壤细菌、真菌和放线菌数量均低于对照样地,说明豚草对土壤微生物数量具有一定的抑制作用.三裂叶豚草对土壤微生物数量的抑制作用大于普通豚草.豚草的抑菌效应可为新药源、绿色农药等的开发提供参考.     

Advances on studies of miR-21 in vascular endothelial function and angiogenesis

MicroRNAs (miRNAs)are a class of non-coding, endogenous, single-stranded small RNA molecules composed of 19~25 nucleotides. miRNAs are widely involved in the process of human life activities. Recent studies have shown that part of miRNAs regulate the vascular endothelial function and angiogenesis. High expression of miRNA-21 is found to play important roles in the cell proliferation, cell apoptosis, cell growth and death of vascular endothelial cells. This review will focus on the recent progress related to miRNAs in vascular endothelial function and angiogenesis, providing a new insight in cardiovascular disease prevention, clinical diagnosis, prognosis and target therapeutics.     

Inhibition of c-Myc by 10058-F4 overcomes imatinib resistance in chronic myeloid leukemia cells

AIM：To investigate the effect of c-Myc inhibitor 10058-F4 on human chronic myeloid leukemia (CML) K562 cells and imatinib-resistant K562/G cells. METHODS：The protein expression of c-Myc was detected by Western blotting. Cell proliferation was evaluated by MTT assay and colony formation assay. PI staining was used to determine the cell cycle distribution. Annexin V-PI staining was applied for apoptosis detection. RESULTS：Imatinib-resistant K562/G cells displayed lower sensitivity to imatinib than K562 cells with high expression of c-Myc. Treatment with specific c-Myc inhibitor 10058-F4 inhibited the cell proliferation in a dose- and time-dependent manner, and K562/G displayed more sensitivity to 10058-F4 than K562 cells. 10058-F4 also induced cell cycle arrest in G0/G1 phase and induced apoptotic cell death in the 2 cells. Importantly, 10058-F4 suppressed the colony formation ability in K562 and K562/G cells. CONCLUSION：c-Myc is a novel target to overcome imatinib-induced drug resistance, and c-Myc inhibitor provides a new approach in CML therapy.