MicroRNA-200a affects malignant biological behaviors of breast cancer cells by inhibiting epithelial-mesenchymal transition

AIM: To investigate the effect of microRNA-200a (miR-200a) on the malignant biological beha-viors of breast cancer cells and its regulatory mechanism. METHODS: The expression of miR-200a in human breast can-cer cell lines MDA-MB-231, MDA-MB-468 and MCF-7, and normal human mammary epithelial cell line MCF-10A was detected by RT-qPCR. CCK-8 assay was used to detect the viability of MDA-MB-231 cells after transfection with miR-200a mimic or miR-200a inhibitor. Flow cytometry method and Transwell assay were used to detect the apoptosis and invasive ability of MDA-MB-231 cells after transfection with miR-200a mimic or miR-200a inhibitor. The expression of SIP1, E-cadherin, N-cadherin, Snail, Twist, ZEB1 and ZEB2 at mRNA and protein levels was determined by RT-qPCR and Western blot. RESULTS: Compared with MCF-10A cells, the lowest expression of miR-200a was observed in the MDA-MB-231 cells (P<0.05). Over-expression of miR-200a attenuated the viability of MDA-MB-231 cells (P<0.05), increased apoptosis (P<0.05) and decreased the invasion ability (P<0.05). The expression of SIP1, N-cadherin, Snail, Twist, ZEB1 and ZEB2 at mRNA and protein levels was also significantly down-regulated, while the mRNA and protein expression of E-cadherin was significantly increased (P<0.05). Transfection with miR-200a inhibitor reversed the above results. CONCLUSION: Up-regulation of miR-200a inhibits the viability and invasion ability of MDA-MB-231 cells and promotes the apoptosis of MDA-MB-231 cells. miR-200a may regulate the biological behaviors of breast cancer by inhibiting epithelial-mesenchymal transition.     

Relationship between the temperature and the overwintering of water lettuce (Pistia stratiotes) at Kowataike,a branch of Yodogawa River,Japan

The successful overwintering of water lettuce (Araceae, Pistia stratiotes L.) is reported in Kowataike, a pond in Kyoto Prefecture, Japan, in the temperate climate zone. Overwintering was observed in the northern zone of Kowataike, where warm water discharge flows from an upstream electrical appliance factory. From December 2007 to January 2008, several overwintering water lettuce plants were observed in the northern zone where the water temperature was abnormally high (average: 21.9°C; low: 19.5°C). Water in the central zone of Kowataike was isolated from the warm water discharge. The temperatures here were much lower (average: 8.2°C; low: 4.2°C) and no water lettuce plant survived here. The overwintering in the northern zone fluctuated annually. This fluctuation appeared to be correlated with the period of warm water discharge, which varied from year to year and resulted in higher water temperatures most, but not all, of the winter. The results suggest that artificial environmental factors, such as anthropogenic warm water discharge, could enable water lettuce to overwinter. In the northern zone of Kowataike under the influence of the warm water discharge, only small water lettuce plants overwintered. This may be attributed to the presence of older plants with larger leaves that seemed to protect the small rosettes from frost. Second, the air warmed by the warm discharge accumulated in the space under the piles of dead large leaves, which created conditions similar to those of a greenhouse. These two mechanisms apparently allow the small water lettuce plants to be surrounded by moderate atmospheric conditions.     

A Phytophthora conserved transposon‐like DNA element as a potential target for soyabean root rot disease diagnosis

A transposon‐like element, A3aPro, with multiple copies in the Phytophthora sojae genome, was identified as a suitable detection target for this devastating soyabean root rot pathogen. The PCR primers TrapF1/TrapR1 were designed based on unique sequences derived from the transposon‐like sequence. A 267‐bp DNA fragment was amplified using this primer pair, the specificity of which was evaluated against 118 isolates of P. sojae, 72 isolates of 25 other Phytophthora spp., isolates of Pythium spp. and isolates of true fungi. In tests with P. sojae genomic DNA, detection sensitivities of 10 pg and 10 fg DNA were achieved in standard PCR (TrapF1/TrapR1) and nested PCR (TrapF1/TrapR1 and TrapF2/TrapR2), respectively. Meanwhile, PCR with TrapF1/TrapR1 primers detected the pathogen at the level of a single oospore, and even one zoospore. These primers also proved to be efficient in detecting pathogens from diseased soyabean tissues, residues and soils. In addition, real‐time quantitative PCR (qPCR) assays coupled with the TrapF1/TrapR1 primers were developed to detect and quantify the pathogen. The results demonstrated that the TrapF1/TrapR1 and TrapF2/TrapR2 primer‐based PCR assay provides a rapid and sensitive tool for the detection of P. sojae in plants and in production fields.     

Effects of gemcitabine on inhibiting proliferation and inducing apoptosis of CD34+CD38- myeloid leukemia stem cells

AIM：To investigate the effects of gemcitabine (GEM), a novel analog of deoxycytidine and nucleoside reductase inhibitor similar to cytarabine (Ara-C) in structure, on the proliferation and apoptosis of myeloid leukemic stem cells (LSCs), CD34+CD38-KG1a cells. METHODS：The expression of CD34 and CD38 on the surface of acute myeloid leukemia KG1a cells was detected by flow cytometry. The effects of GEM at various concentrations for 24 h and sustained medication for 14 d and 21 d on the proliferation and colony-forming ability of KG1a cells were analyzed by soft agar colony-forming experiment. The changes of the cell cycle of KG1a cells treated with various concentrations of GEM were tested by flow cytometry. The apoptosis of KG1a cells was determined by flow cytometry with the staining of Annexin V-FITC and propidium iodide (PI). RESULTS：The percentage of CD34+CD38- cells in acute myeloid leukemia KG1a cells was (98.02±0.72)%.Treatments with 0.05 mg/L and 0.1 mg/L GEM for 24 h were similar to saline control group in cell cycle distribution of the KG1a cells, whereas KG1a cells treated with 0.5 mg/L GEM for 24 h were arrested at G0/G1 phase. After treatment with 0.1 mg/L and 0.5 mg/L GEM for 24 h, the colony numbers at 14 d and 21 d were lower than that in saline control group. No difference of the colony numbers between the cells treated with normal saline and 0.05 mg/L GEM for 14 d and 21 d was observed. After sustained medication with 0.05 mg/L, 0.1 mg/L and 0.5 mg/L GEM and Ara-C for 14 d and 21 d, the colony numbers decreased as compared to saline control group. Treatment with 0.5 mg/L GEM for 24 h increased the apoptotic rate of KG1a cells compared with saline control group, while treatments with 0.05 mg/L and 0.1 mg/L GEM for 24 h were similar to saline control group in cell apoptosis. CONCLUSION：GEM inhibits the proliferation and colony-forming ability, arrests the cell cycle at G0/G1 phase and induces apoptosis of CD34+CD38- acute myeloid leukemia cells.     

渐进式干旱对辽东栎幼树光合特性的影响及敏感性分析

目的 探究辽东栎幼树叶片的光合系统对土壤渐进式干旱的响应,并筛选干旱敏感性指标。 方法 采用盆栽渐进式干旱胁迫法,对2年生辽东栎幼苗叶片的叶倾角、叶绿素荧光、光合作用等指标进行方差分析（ANOVA）和LOESS非线性拟合。 结果 渐进式干旱对光合气体交换的影响最显著,其次是叶倾角,最后是光系统II（PSII）的电子传递和能量耗散。依据土壤相对含水量（SRWC）对光合特性的影响,辽东栎幼树光合系统的干旱响应可划分为4个阶段：第1阶段（胁迫未发生,26%＞SRWC＞20%),光合气体交换参数无下降;第2阶段（中度胁迫,20%＞SRWC＞14%）,气孔限制效应明显,叶倾角降低至−14.0 ± 1.7°;第3阶段（重度胁迫,14%＞SRWC＞8%）,叶片水分利用效率（WUE）显著下降,叶倾角值降低至−43.2 ± 10.3°,光合气体交换明显减少,表明SRWC降低至14%是辽东栎幼树的灌溉临界值;第4阶段（极度胁迫,SRWC＜8%）,PSII的电子传递和能量耗散显著改变,光合机构严重受损,叶倾角值降低至−68.5 ± 6.7°,表明SRWC降低至8%是辽东栎幼树叶片的致死临界值。基于叶倾角对土壤干旱的响应存在阶段性差异,其可作为辽东栎幼树灌溉临界值的预警指标;PSⅡ单位面积有活性反应中心数量RCO/CS、单位反应中心吸收的能量ABS/RC、单位反应中心以热能形式耗散的能量DIO/RC、叶片性能指数PIABS可作为叶片致死的预警指标。 结论 本研究观察到辽东栎幼树叶片光合系统对土壤干旱的响应存在阶段性差异,据此确定了灌溉临界值和反映土壤干旱的敏感性指标,可以为辽东栎幼树高效灌溉策略的制定提供理论基础。     

气象信息化在许昌现代农业的应用与思考

通过系统介绍许昌农业气象信息化的发展历程,着重介绍了农业气象信息化网络的构成、服务方式、建设成果,以及许昌现代农业气象信息化的四种发展模式,即乡级农业气象信息服务站、特色农业气象信息服务协会、手机大喇叭、涉农气象信息服务站,并对未来许昌农业气象信息化发展思路和方向进行展望,提出了气象信息化在许昌现代农业中应用的合理化建议。     

机械化对蛋鸡规模养殖技术效率的影响

机械化是实现畜禽养殖规模化的基础,同时也是提升畜禽养殖效率的动力源泉,开展有关机械化对畜禽养殖技术效率影响的研究对提升中国畜禽养殖水平、实现畜禽养殖现代化和规模化具有重要意义。该文以蛋鸡为例,利用中国5个鸡蛋主产省份蛋鸡规模养殖户的实地调研数据,采用数量分析方法研究了机械化对蛋鸡养殖技术效率的影响。研究表明,虽然目前规模养殖户蛋鸡养殖的机械化水平较低,但机械化有效提升了蛋鸡规模养殖技术效率,体现出了机械化在提升蛋鸡养殖综合技术效率、纯技术效率上的优势;户主受教育程度、是否参加过养殖培训、养殖规模对蛋鸡养殖的技术效率具有显著的正向影响,而从事蛋鸡养殖的劳动力数量对蛋鸡养殖技术效率具有显著的负向影响。此外,规模养殖户蛋鸡养殖技术效率存在显著的地区差异。     

大豆发状根乙醇诱导表达系统的建立及验证

为在大豆中建立目的基因表达可控的化学诱导表达系统,本研究构建了基于乙醇诱导表达系统(ALCA switch)的GUS和GmFT2a表达载体,利用发状根农杆菌介导的根系转化体系,分别获得转ALCA-mini35S-GUS和ALCA-mini35S-GmFT2a的发状根,通过检测GUS的表达情况和GUS酶活性高低评定该系统在大豆发状根中的诱导效率,并通过检测GmFT2a表达水平加以验证。结果表明,在非诱导条件下,ALCA-mini35S-GUS发状根中未见GUS表达,而在培养基中添加乙醇后组织化学染色效果明显,说明GUS基因表达。乙醇诱导表达的效率与乙醇浓度有关,当乙醇浓度为0.05%、处理60 h时GUS相对表达量达到最高值,处理72 h时GUS酶活性最高;0.05%乙醇处理72 h时,ALCA-mini35S-GmFT2a发状根中GmFT2a相对表达量平均值约为诱导前的150倍,个别样本可达初始值的400倍。综上所述,乙醇诱导表达系统可以在大豆发状根中发挥作用,该系统不仅可用于大豆基因功能研究,而且可为培育外源基因表达可控的转基因大豆品种提供新的技术手段。     

Soil mineral nitrogen dynamics in fallow periods in a rainfed semiarid Mediterranean agricultural systems

Rainfed agricultural systems in semiarid Mediterranean environments are subject to erratic but often heavy rainfall events.As an agronomic practice,fallow periods can be included even within the existing European Union common policy for crop diversification.This study aimed to quantify the effects of previous mineral fertilization on soil mineral nitrogen (Nmin) content and potential nitrate leaching during no-till fallow periods of crop rotation.The Leaching Estimation and Chemistry Model (LEAC...