Chronic hypoxia enhances aggressiveness of MCF-7 breast cancer cells through EMT

AIM: To investigate the effects of chronic hypoxia on the aggressiveness of MCF-7, a human breast cancer cell line, and the underlying mechanisms.METHODS: MCF-7 cells were cultured under hypoxia (1% O₂, 5% CO₂ and 94% N₂) or control (95% O₂ and 5% CO₂) condition. The viability, proliferation, and invasion and migration abilities of the MCF-7 cells were determined by MTT assay, CCK-8 assay, cell counting, and cell invasion and migration assays. Anchorage-independent growth and the alteration of cellular polarization of the MCF-7 cells were tested by soft agar colony formation assay and Matrigel-3D culture assay, respectively. The effects of chronic hypoxia on the growth and metastasis of MCF-7 cells in vivo were investigated by xenograft in nude mice. The morphological changes of the MCF-7 cells were observed under an inverted microscope. Hypoxia-induced alterations in the levels of hypoxia inducible factor-1 (HIF-1) and phosphorylated glycogen synthase kinase-3β (p-GSK-3β) as well as epithelial-mesenchymal transition (EMT) molecules, such as E-cadherin, N-cadherin, vimentin, matrix metalloproteinase (MMP)-3 and MMP-9, were determined by Western blot.RESULTS: Chronic hypoxia significantly increased the viability, proliferation, and invasion and migration abilities of MCF-7 cells in vitro, enhanced the anchorage-independent growth, facilitated cellular polarization alteration in Matrigel-3D culture, and promoted cancer metastasis in vivo. Hypoxia up-regulated HIF-1, activated GSK-3β, down-regulated E-cadherin and increased the protein levels of N-cadherin, vimentin, MMP-3 and MMP-9. CONCLUSION: Chronic hypoxia enhances the aggressiveness of breast cancer cells probably through EMT.     

乳清蛋白对以麦芽糊精为助剂桑葚汁喷雾干燥性能影响

桑葚富含多酚类物质,具有一定的营养与保健功能。多酚类物质在加工及贮藏过程中非常不稳定,喷雾干燥法微胶囊包埋是保护生物活性成分常采用的方法。但是,果汁喷雾干燥过程中极易出现黏壁现象,导致粉末回收率较低。基于此,研究不同比例乳清分离蛋白(WPI)与麦芽糊精(MD)对喷雾干燥桑葚粉理化特性的影响。结果表明,进料液中以少量WPI取代MD能显著提高桑葚粉的回收率,WPI较高的表面活性与良好的成膜性是使桑葚粉回收率提高的主要原因。随着进料溶液中WPI质量分数的增加,桑葚粉含水率增加;水分活度、堆积密度、粒径、水溶性指数和玻璃化转变温度呈降低趋势,而吸湿性则无明显变化。随着进料溶液中WPI质量分数的增加,桑葚粉L值、b值增加,a值降低,色差ΔE增加。桑葚粉的总酚含量与清除自由基能力随进料溶液中WPI质量分数的增加呈降低趋势。当进料溶液中桑葚汁/MD/WPI质量比为65∶(34.5~30.0)∶(0.5~5.0)时,既能有效解决黏壁问题,又能较好地抑制桑葚汁中多酚类成分降解,使桑葚粉具有较高的抗氧化能力。     

MicroRNA-145 inhibits epithelial-mesenchymal transition in human renal cancer A-498 cells by ADAM28

AIM: To investigate the inhibitory effect of microRNA-145 (miR-145) on epithelial-mesenchymal transition (EMT) in renal cancer A-498 cells. METHODS: The A-498 cells were transfected with miR-145 mimics (M145) and mimic negative control(MNC), which served as M145 group and MNC group, respectively. Mock control (MC) group was set up using untreated A-498 cells. The expression level of miR-145 in each group was detected by RT-qPCR. Transwell assay was used to detect the invasion ability of the cells. The protein expression of vimentin, E-cadherin and ADAM28 was determined by Western blot. Bioinformatic method was used to predict the target genes of miR-145. Antagonistic effect of ADAM28 over-expression on the inhibition of EMT by miR-145 was detected by Western blot. The relationship between miR-145 and ADAM28 was analyzed by dual-luciferase reporter assay. RESULTS: The expression level of miR-145 in M145 group was significantly up-regulated than that in MC group (P<0.05). The number of invasive cells in M145 group was 12.78±3.37, which was significantly lower than that in MC group (P<0.05). ADAM28 may be the target gene of miR-145. Compared with MC group, the protein expression of vimentin and ADAM28 in M145 group was significantly decreased (P<0.05), while the protein expression of E-cadherin was significantly increased (P<0.05).After ADAM28 over-expression, the protein expression of vimentin in the A-498 cells of M145 group was significantly increased (P<0.05), and the protein expression of E-cadherin was significantly decreased (P<0.05). The results of dual-lucife-irasei reporter assay showed that ADAM28 was a downstream target gene of miR-145. CONCLUSION: miR-145 may inhibit the expression of EMT-related proteins through the downstream target gene ADAM28 and inhibit the EMT process of renal cancer A-498 cells.     

水稻干燥过程应力裂纹产生的机理研究

通过水稻干燥和缓苏过程中稻谷爆腰产生的玻璃化转变分析,确定稻谷在玻璃态下干燥时对爆腰增殖无影响。建议采用2种措施：一是使稻谷在玻璃态下干燥,抑制爆腰产生;二是使稻谷在较高温度下干燥一定时间后,给稻谷缓苏足够时间以降低内部水分梯度,使内部水分均匀,有效地降低稻谷裂纹率和提高产米率。     

热泵干燥南美白对虾品质特性与玻璃化转变关系研究

针对南美白对虾热泵干燥过程中常出现物理、化学反应导致虾肉品质下降,而其机理又尚未明确的问题,采用静态称量法研究了南美白对虾肉的解吸等温线,利用差示扫描量热仪测定了虾肉的玻璃化转变温度(Tg)。分别采用GAB模型与Gordon-Taylor方程拟合水分吸附与Tg数据。虾肉在热泵干燥温度35℃、风速1.5 m/s下进行干燥,每隔1.0 h取样,分析虾肉品质特性(色泽、收缩程度、硬度与韧性和虾青素质量比)。基于玻璃化转变理论,阐明虾肉热泵干燥品质变化机制。结果表明,虾肉热泵干燥过程中,基质处于橡胶态,体系流动性增加,导致干制品品质下降。     

德国可再生能源发展的借鉴与启示

近年来,可再生能源逐渐成为世界各国关注的热点,并成为各国应对气候变化以及生态环境保护的共同选择,其在经济发展以及维护生态环境中开始被重视起来.德国能源转型的成功已经成为欧美国家中的典范,为此农业农村部科技教育司组团赴德国参加"农业废弃物资源化利用和农村清洁能源综合利用技术"培训项目,笔者结合培训内容和实地考察形成该篇文...     

基于库兹涅茨曲线的中国南方集体林区森林质量转型动因分析

森林转型理论提供了全球可能经历的森林恢复途径,但已有研究主要关注森林数量.文中从广义上提出森林多维转型并重点关注森林质量转型,从森林生长性、树种多样性、结构稳定性和森林健康性4个方面对森林质量进行衡量,通过构建森林转型影响因素分析框架对中国南方集体林区10个省(区)(浙江、安徽、福建、江西、湖北、湖南、广东、广西、贵州...     

种子理化反应与种子衰老关系的研究进展

植物种子衰老是一个十分复杂的过程,是各种理化反应和生理生化反应的综合结果。国外几个研究小组近10年的研究证实,种子细胞质以玻璃态存在,其玻璃化转变温度与种子衰老密切相关,而玻璃化温度又与种子中的糖、蛋白等物质有关。还有一些研究表明,种子中存在被称为美拉德反应和阿马多瑞反应的非酶促反应,这些反应可以在种子水分含量极低的条件下发生,其产物在种胚内的积累成为种子衰老的原因,其机理可能是通过降低抗氧化酶的活性、修饰蛋白质、核酸的结构和功能、影响种子中糖代谢等途径进而引起种子衰老。     

基于结构转换视角的中国重点国有林区经济转型发展路径分析

在我国全面停伐背景下, 实现国有林区经济社会转型迫在眉睫。文中测算、对比和评价2003—2014年全国及重点国有林区产业结构转换速度和方向, 以期掌握重点国有林区近年产业结构变动的基本特征, 得到以下结论:1)重点国有林区各森工林区产业结构转换速度普遍较慢, 同一林区不同产业的增速差异化不显著; 2)重点国有林区产业结构转换方向总体合理, 三次产业比重变动趋势有助于实现林区产业效率均衡与结构稳定; 3)重点国有林区产业结构转换能力整体低于全国水平。根据研究结论, 从巩固非林替代产业、培育主导产业、因地制宜进行产业结构与布局调整、注重制度配套以及深化体制改革等方面提出支撑重点国有林区产业结构调整与经济转型发展的可行路径。     

海河流域土地利用及覆盖变化研究

基于1970、1980、1990、2000和2008年五期的MSS、TM与ETM遥感影像数据,对海河流域1970~2008年土地利用的变化及其驱动因素进行研究,为充分揭示不同土地利用类型转移特征在土地结构整体变化中的地位和作用,利用ARCGIS数据集成分析平台,将不同时段土地利用图叠加,统计不同土地利用类型在1970~1990年与1990~2008年两个比较时段的转移概率矩阵.近30年来海河流域土地利用结构一直是以耕地和林地为主导的土地覆盖格局,园地、工业用地、住宅用地显著增加,耕地和其它用地则明显减少,在定量刻画土地利用变化的基础上,初步探讨了影响流域内土地格局变化的驱动因素,主要为自然因素以及政策导向、产业结构调整、人口增长等社会经济因素.目前海河流域正处于快速城市化阶段,生产性用地快速增长,耕地面积迅速减少,林地面积变化不大,各级土地管理部门应采取切实有效的措施遏制流域内耕地不合理非农化,保证经济效益、社会效益和生态效益协调增长