Horizontal transfer of microRNAs: molecular mechanisms and clinical applications

A new class of RNA regulatory genes known as microRNAs (miRNAs) has been found to introduce a whole new layer of gene regulation in eukaryotes. The intensive studies of the past several years have demonstrated that miRNAs are not only found intracellularly, but are also detectable outside cells, including in various body fluids (e.g. serum, plasma, saliva, urine and milk). This phenomenon raises questions about the biological function of such extracellular miRNAs. Substantial amounts of extracellular miRNAs are enclosed in small membranous vesicles (e.g. exosomes, shedding vesicles and apoptotic bodies) or packaged with RNA-binding proteins (e.g. high-density lipoprotein, Argonaute 2 and nucleophosmin 1). These miRNAs may function as secreted signaling molecules to influence the recipient cell phenotypes. Furthermore, secreted extracellular miRNAs may reflect molecular changes in the cells from which they are derived and can therefore potentially serve as diagnostic indicators of disease. Several studies also point to the potential application of siRNA/miRNA delivery as a new therapeutic strategy for treating diseases. In this review, we summarize what is known about the mechanism of miRNA secretion. In addition, we describe the pathophysiological roles of secreted miRNAs and their clinical potential as diagnostic biomarkers and therapeutic drugs. We believe that miRNA transfer between cells will have a significant impact on biological research in the coming years.     

Some New Records of Ferns from Vietnam and Laos (3)Pteris (Pteridaceae)

Genus Pteris from Vietnam and Laos is revised in this paper. Seven species newly reported from Vietnam and Laos are P.argyraea, P.sichuanensis, P.maclurei, P.pseudopellucida, P.setuloso costulata, P.morii, and P.wangiana.     

灰飞虱Bursicon基因的克隆、序列分析及在不同发育阶段的表达

Bursicon是通过G蛋白受体调节昆虫表皮硬化及展翅的功能蛋白, 它在昆虫蜕皮后的表皮硬化过程中起着关键作用。为探讨灰飞虱Laodelphax striatellus的 bursicon的功能, 利用RT-PCR和RACE技术克隆获得1 126 bp的bursicon α和761 bp的bursicon β全长序列, 将其分别命名为Lsburs-α和Lsburs-β。生物信息学分析表明： Lsburs-α开放阅读框长483 bp, 编码160个氨基酸, 该蛋白具有2个N-豆蔻酰化位点、 3个酪蛋白激酶Ⅱ磷酸化位点以及2个蛋白激酶C磷酸化位点。Lsburs-β开放阅读框长417 bp, 编码138个氨基酸, 该蛋白具有2个N-豆蔻酰化位点、 3个酪蛋白激酶Ⅱ磷酸化位点以及1个酪氨酸激酶磷酸化位点。qRT-PCR结果表明： Lsburs-α和Lsburs-β在灰飞虱各龄期均有转录表达, 并在若虫期随龄期增加呈上升趋势, 在羽化期达到峰值, 成虫期表达量逐渐降低。结果提示bursicon与灰飞虱蜕皮后的外表皮硬化关系密切。本文结果为深入研究bursicon的功能、受体调节和信号通路等奠定了基础。     

基于植被数量分类的排水疏干影响下若尔盖高原沼泽退化特征

2009年,在对若尔盖高原沼泽的生态特征、环境质量考察和排水疏干沼泽样带生态调查的基础上,采用TWINSPAN分类方法,将研究区20个典型沼泽样地划分为原始沼泽、长期排水退化沼泽和短期排水退化沼泽3种类型,每类退化沼泽包含轻度退化、中度退化和重度退化3个退化等级,研究不同程度退化沼泽的植被和土壤退化特征.结果表明: 若尔盖高原沼泽退化主要受排水方式、排水强度和土壤水分梯度的驱动.植物群落退化过程较土壤退化过程变化明显.其中,植物群落水分生态型的结构变化最显著,在长期排水和短期排水的影响下,沼生植物重要值由0.920分别下降至0.183和0.053,中生植物重要值由0.029分别上升至0.613和0.686.土壤对沼泽退化的响应具有滞后性,其理化性质呈一定的变化规律,但差异尚未达到显著水平.土壤水分和氮、钾等养分含量是影响若尔盖高原排水疏干退化沼泽植物物种分布的关键因素.     

Effects of iron deficiency on the growth and photosynthesis of three bloom‐forming cyanobacterial species isolated from Lake Taihu

Cyanobacterial blooms are found in many freshwater ecosystems around the world, but the effect of environmental factors on their growth and the proportion of species still require more investigation. In this study, the physiological responses of bloom‐forming cyanobacteria M icrocystis aeruginosa FACHB912, M icrocystis flos‐aquae FACHB1028 and P seudanabaena sp. FACHB1282 to iron deficiency were investigated. Their specific growth rates were found to decrease as the available iron concentration decreased. At low available iron concentrations of 1 × 10^?7 M (pFe 21.3) and 5 × 10^?8 M (pFe 21.6), M . aeruginosa had the lowest specific growth rate among three studied species. The cell sizes of M . flos‐aquae and Pseudanabaena sp. were significantly smaller under the lowest iron concentration. The chlorophyll a content of the three species decreased at the lowest iron concentration. The maximal relative electron transport rate, photosynthetic efficiency, and light‐saturation parameter of M . aeruginosa were lower than the other two cyanobacteria at pFe 21.3. Therefore, M . aeruginosa was the least able to adapt to iron deficiency. Under iron deficiency, the functional absorption cross‐section of PSII and electron transport rate on the acceptor side of PSII decreased in M . aeruginosa, while the connectivity factor between individual photosynthetic units increased in M . flos‐aquae, and the electron transport rate on the acceptor side of PSII and between PSII and PSI decreased in P seudanabaena sp. The ability to store iron was highest in M . flos‐aquae, followed by P seudanabaena sp. and M . aeruginosa. Thus, these results provide necessary information for detecting the role of iron in the succession of cyanobacterial species in Lake Taihu, the third largest freshwater lake in China, because all three species were isolated from this lake.     

Characterization of Smad3 knockout mouse derived skin cells

TGF-β plays an important role in skin wound healing process, in which Smad3 acts as a signaling molecule. Smad3 knockout mice exhibit enhanced wound healing and less inflammatory process, but the intrinsic properties of the mouse derived skin cells are generally unexplored. The purpose of this study is to characterize the biological behavior of skin cells derived from Smad3 knockout mice and thus to define the mechanism of this particular wound healing process. Keratinocytes and dermal fibroblasts were harvested from the skin of Smad3 knockout (Smad3 KO) and wild-type (WT) mice and in vitro cultured for one and two passages for various experiments. The results showed that KO mouse serum contained significantly higher levels of TGF-β1 and lower level of IL-6 and IL-10 than WT mouse serum (p < 0.05), which were also supported by the same findings of more TGF-β1 and less IL-6 and IL-10 in the supernatant of cultured KO dermal fibroblasts than those of WT cells (p < 0.05). At gene levels, IL-6, IL-10, and TGF-β1 were significantly less expressed in KO fibroblasts than in WT fibroblasts (p < 0.05). In addition, KO dermal fibroblasts also exhibited stronger migration and proliferation potentials than WT fibroblasts (p < 0.05). Moreover, both KO fibroblasts and keratinocytes showed higher colony-forming efficiency than WT counterparts with significant difference (p < 0.05). These findings indicate that both systemic factors and intrinsic properties of skin cells contribute to enhanced wound healing and less inflammatory reaction observed in Smad3 knock-out mice.     

Upregulated microRNA-224 promotes ovarian cancer cell proliferation by targeting KLLN

Human epithelial ovarian cancer is a complex disease, with low 5-yr survival rate largely due to the terminal stage at diagnosis in most patients. MicroRNAs play critical roles during epithelial ovarian cancer progression in vivo and have also been shown to regulate characteristic of ovarian cancer cell line in vitro. Alterative microRNA-224 (microRNA-224) expression affects human epithelial ovarian cancer cell survival, apoptosis, and metastasis. However, people know little about the effects of microRNA-224 on epithelial ovarian cancer cell proliferation. In the current study, we found that the microRNA-224 expression level of human syngeneic epithelial ovarian cancer cells HO8910 (low metastatic ability) was lower than that of HO8910PM (high metastatic ability). Furthermore, microRNA-224 was confirmed to target KLLN in HO8910 and HO8910PM. The known KLLN downstream target cyclin A was regulated by microRNA-224 in HO8910 and HO8910PM. In addition, overexpression of microRNA-224 enhanced the proliferation abilities of HO8910 and knockdown of microRNA-224 suppressed the proliferation abilities of HO8910PM by KLLN-cyclin A pathway. Our results provide new data about microRNAs and their targets involved in proliferation of epithelial ovarian cancer cells by modulating the downstream signaling.