哺乳动物中RNA干扰研究进展

RNA干扰(RNAi)由双链RNA引起,广泛存在于动、植物中的序列特异性转录后基因沉默,是生物体在进化过程中,抵御病毒感染及由于重复序列和突变引起的基因组不稳定性的保护机制。论文从RNAi现象、RNAi发生机制、哺乳动物中的RNAi现象和RNAi与抗病毒感染等几个方面做了综述,详细介绍RNAi在哺乳动物中的应用。     

Effect of shRNA-mediated survivin gene silencing on sensitivity of lymphoma cells to adriamycin

AIM: This study was designed to use RNA interference technique to down-regulate the expression of survivin gene in human Burkitts lymphoma cell line Daudi and to explore the effect on sensitivity of Daudi cells to adriamycin. METHODS: The survivin-shRNA expression vector was constructed and transfected into Daudi cells. Expression of survivin mRNA and protein were assessed by RT-PCR and Western blotting analysis, respectively. Apoptosis index of transfected Daudi cells was quantified by flow cytometry. The sensitivity of Daudi cells to adriamycin (ADR) before and after transfection was detected by MTT test. RESULTS: The mRNA and protein levels of survivin were down-regulated by 62.32% and 61.88%, respectively, compared to those in control-shRNA treated group and PBS treated group (P<0.05). Meanwhile, the apoptosis index was significantly increased (19.10%±2.15%), compared to that in control group (4.48%±1.54%) and PBS group (4.35%±1.37%, P<0.05). The 50% inhibition concentration (IC50) of ADM to Daudi cells was significantly decreased (0.25±0.43) μmol/L, compared to that in control group (0.87±0.21) μmol/L and PBS group (0.91±0.36) μmol/L, P<0.05. CONCLUSION: Down-regulation of survivin expression in Daudi cells by shRNA effectively induces apoptosis and increases the sensitivity of Daudi cells to ADR.     

Breeding for provitamin A biofortification of maize (Zea mays L.)

Vitamin A deficiency is widely prevailing in children and women of developing countries. Deficiency of vitamin A causes night blindness, growth retardation, xerophthalmia and increases the susceptibility against epidemic diseases. Among different interventions of overcoming malnutrition, biofortification is the most acceptable and preferred intervention among researchers, growers and consumers. Maize is grown and consumed in those regions where vitamin A deficiency is most prevalent; thus, targeting this crop for provitamin A biofortification is the most appropriate solution. Different breeding strategies including diversity analysis, introduction and stability analysis of exotic germplasm, hybridization, heterosis breeding, mutagenesis and marker‐assisted selection are practised for exploring maize germplasm and development of provitamin A‐enriched cultivars. Genome‐wide association selection and development of transgenic maize genotypes are also being practised, whereas RNA interference and genome editing tools could also be used as potential strategies for provitamin A biofortification of maize genotypes. The use of these breeding strategies for provitamin A biofortification of maize is comprehensively reviewed to provide a working outline for maize breeders.     

浑水膜孔灌多向交汇入渗及减渗特性

浑水灌溉是我国黄河流域引黄灌区灌溉的主要特点,其中浑水中的泥沙含量对土壤入渗特性有较大的影响,为揭示浑水膜孔灌交汇入渗的减渗特性,通过开展浑水及清水膜孔灌入渗试验,建立了浑水膜孔灌自由入渗相对于清水的减渗率及浑水膜孔灌多向交汇入渗相对于自由入渗的减渗率与入渗时间之间的量化关系,提出了由清水膜孔灌自由入渗量推求浑水膜孔灌多向交汇入渗量的模型。结果表明:浑水膜孔灌自由入渗较清水的减渗量随入渗时间的延长而增大,但增大幅度慢慢变小,入渗后期其减渗量基本呈线性增加,其减渗率随时间的增大先快速增大后缓慢减小,入渗后期减渗率基本稳定;当入渗产生交汇后,入渗能力明显减小,多向交汇入渗和单向交汇入渗相对自由入渗的减渗率均随入渗时间的增长而增大,多向交汇入渗相对单向交汇入渗也存在减渗作用,3条减渗率曲线的变化率随着时间的增长而逐渐减小。     

半固体人工饲料饲养日本通草蛉幼虫对荻草谷网蚜捕食作用

为评价一种半固体人工饲料饲养的日本通草蛉幼虫的捕食潜力,在室内研究了1~3龄幼虫对荻草谷网蚜的捕食作用和种内干扰作用。结果表明,1~3龄幼虫的捕食量随着猎物密度的增加而上升,当猎物密度增加到一定水平,捕食量趋向稳定,捕食功能反应曲线均符合Holling Ⅱ型方程。不同龄期幼虫对荻草谷网蚜理论最大日捕食量分别为42、179、204头。2龄幼虫的干扰效应用Hassell &Varley的模式(E=QP^-m)进行模拟,模拟模型为E=0.5074P^-0.6627,结果说明随着2龄幼虫密度的增大,其捕食作用率随之减小。     

不同膜孔直径的浑水膜孔灌单向交汇入渗特性

根据室内浑水膜孔灌单向交汇入渗试验资料,研究了不同膜孔直径的浑水膜孔灌单向交汇入渗特性;建立了浑水膜孔灌单向交汇入渗参数、单向交汇时间、湿润锋运移参数与不同膜孔直径的关系;提出了不同膜孔直径的浑水膜孔灌单向交汇入渗单位膜孔面积累积入渗量模型、稳定入渗率模型、自由面和交汇面湿润锋运移模型。结果表明:随着膜孔直径增大,单点膜孔累积入渗量逐渐增大,单位膜孔面积累积入渗量逐渐减小;单位膜孔面积累积入渗量的K值随着膜孔直径的增大而减小,α随着膜孔直径的增大而逐渐增大;在膜孔间距一定的情况下,入渗发生交汇的时间随着膜孔直径的增大而减小;在相同入渗时间内,随着膜孔直径的增大,自由面和交汇面垂直和水平湿润锋运移距离都逐渐增加。