[Show abstract][Hide abstract] ABSTRACT: Accumulating evidence has implicated the deregluation of miRNAs in tumorigenesis. Previous studies have reported that microRNA-195 (miR-195) is markedly down-regulated in human glioblastoma cells, compared with normal brain tissue, but the biological role of miR-195 in glioblastoma development is currently unknown. In this study, we define a tumor-suppressor role for miR-195 in human glioblastoma cells. Over-expression of miR-195 in glioblastoma cell lines robustly arrested cell cycle progression and significantly repressed cellular invasion. We identified E2F3 and CCND3 as functional downstream targets of miR-195 in glioblastoma cells. Through knockdown studies, we demonstrated that E2F3 was the dominant effector of miR-195-mediated cell cycle arrest and that CCND3 was a key mediator of miR-195-induced inhibition of glioblastoma cell invasion. Furthermore, we showed that p27(Kip1) was an important regulator downstream of CCND3 and that the accumulation of p27(Kip1) in the cytoplasm might be responsible for the miR-195-mediated cell invasion inhibition in glioblastoma cells. This work provides evidence for the initial mechanism by which miR-195 negatively regulates both the proliferation and invasion of glioblastoma cells, suggesting that the down-regulation of miR-195 might contribute to the malignant transformation of glioblastoma cells and could be a molecular signature associated with glioblastoma progression.
[Show abstract][Hide abstract] ABSTRACT: Although traditional biological treatments effectively reduce the pollution level of paper mill effluent, biologically treated effluent usually can not meet the effluent emission standard. The objective of this study is to investigate the treatment efficiency of the biologically treated effluent by single ozonation and ozonation in the presence of activated carbon (AC), TiO2/AC, Al2O3 and TiO2/Al2O3 catalysts. Results showed that treatment efficiency was enhanced by the simultaneous use of ozone and the catalysts, evaluated as chemical oxygen demand (COD) and color removal rates. The COD and color removal rates reached 51% and 91% for ozonation with TiO2/AC, 55% and 92% for ozonation with TiO2/Al2O3 catalyst, compared with 37% and 83% for single ozonation. It was also found that BOD5/COD effectively increased after ozonation and catalytic ozonation, indicating obvious enhancement of the biodegradability of the effluent.
[Show abstract][Hide abstract] ABSTRACT: Biological, physical and chemical methods have been extensively used to treat paper mill effluent and effectively decreased the pollution level of the effluent. But some poorly- or non-biodegradable organic compounds cannot be degraded through these traditional treatment methods. The objective of this study is to investigate the chemical oxygen demand (COD) degradation kinetics of the paper mill effluent when the effluent was treated by single ozonation and catalytic ozonation with activated carbon (AC), TiO2/AC, Al2O3 and TiO2/Al2O3. Results show that CODcr degradation process of the paper mill effluent studied in this paper with single ozonation and catalytic ozonation should follow apparent second-order kinetics, and catalytic ozonation with AC, TiO2/AC, Al2O3 and TiO2/Al2O3 effectively enhances the reaction rate constant of CODcr degradation of the effluent, compared with single ozonation. The CODcr removal rate and reaction rate constant by single ozonation are 34% and 1.21698×10 -4 (mg/L) -1 •min -1 , and CODcr removal rates and reaction rate constants increase to 35-55% and 1.27775-2.64412×10 -4 (mg/L) -1 •min -1 by catalytic ozonation with AC, TiO2/AC, Al2O3 and TiO2/Al2O3 respectively. It is also found that the content of TiO2 loaded on AC or Al2O3 has important effect on the enhancement of CODcr removal rate and reaction rate constant of the paper mill effluent investigated in this study in the process of ozonation and catalytic ozonation.
[Show abstract][Hide abstract] ABSTRACT: MicroRNAs (miRNAs) are approximately 22-nt small non-coding regulatory RNAs that have generally been considered to regulate gene expression at the post-transcriptional level in the cytoplasm. However, recent studies have reported that some miRNAs localize to and function in the nucleus.
To determine the number of miRNAs localized to the nucleus, we systematically investigated the subcellular distribution of small RNAs (sRNAs) by independent deep sequencing sequenced of the nuclear and cytoplasmic pools of 18- to 30-nucleotide sRNAs from human cells. We identified 339 nuclear and 324 cytoplasmic known miRNAs, 300 of which overlap, suggesting that the majority of miRNAs are imported into the nucleus. With the exception of a few miRNAs evidently enriched in the nuclear pool, such as the mir-29b, the ratio of miRNA abundances in the nuclear fraction versus in the cytoplasmic fraction vary to some extent. Moreover, our results revealed that a large number of tRNA 3' trailers are exported from the nucleus and accumulate in the cytoplasm. These tRNA 3' trailers accumulate in a variety of cell types, implying that the biogenesis of tRNA 3' trailers is conserved and that they have a potential functional role in vertebrate cells.
Our results provide the first comprehensive view of the subcellular distribution of diverse sRNAs and new insights into the roles of miRNAs and tRNA 3' trailers in the cell.
[Show abstract][Hide abstract] ABSTRACT: Deposition of collagen IV in proximal tubule cells (PTCs) plays an important role during diabetic nephropathy, but the mechanism underlying excessive production of collagen IV remains poorly understood. In this study, we examined the miRNA profile of HK-2 cells and found that high glucose/TGF-beta1 induced significant down-regulation of miR-29a. We then showed that miR-29a negatively regulated collagen IV by directly targeting the 3'UTRs of col4a1 and col4a2. These results suggest that miR-29a acts as a repressor to fine-tune collagen expression and that the reduction of miR-29a caused by high glucose may increase the risk of excess collagen deposition in PTCs.
[Show abstract][Hide abstract] ABSTRACT: Abstract-Chemithermomechanical pulping becomes an important development direction for pulp and papermaking industry. But the treatment of its effluent is very difficult because of its high concentration of organic pollutants and the deep color. In this study, eucalyptus chemithermomechanical pulp (CTMP) chemical pretreatment effluent was treated with electrocoagulation, and its treatment efficiency was compared with the traditional chemical coagulation. Results showed that under the conditions of 7.5v cell voltage or 4.43mA/cm2 current density, effluent pH of 6, 25 min treatment time, and 1.0g NaCl addition, CODcr and color removal rates in electrocoagulation treatment reached 40.8% and 90.1% respectively, which were much higher than those of the aluminium chloride and ferric chloride treatment. Based on these results, it is expected that electrocoagulation is a more effective method than chemical coagulation to remove the pollution materials existed in the CTMP chemical pretreatment effluent examined in this study.
[Show abstract][Hide abstract] ABSTRACT: Giardia lamblia is an early diverging and evolutionarily successful protozoan as it can enter into a dormant cyst stage from a vegetative
trophozoite. During dormant stage, its metabolic rate decreases dramatically. However, to date, the regulatory molecules participating
in the initiation and maintenance of this process have not been fully investigated. In this study, we have identified a class
of abundant small RNAs named sitRNAs, which are ∼46 nucleotides in length and accumulate in G. lamblia encysting cultures. Remarkably, they are derived from the 3′ portion of fully matured tRNAs by cleavage of the anticodon
left arm, with the 3′ terminal CCA triplex still connected. During differentiation, only a limited portion of mature tRNAs
is cleaved, but this cleavage occurs almost in the entire tRNA family. sitRNAs begin to accumulate as early as 3 h after initiation
of encystation and are maintained at a relatively stable level during the whole process, exhibiting an expression peak at
around 24 hr. Our studies further show that sitRNAs can be induced by several other stress factors, and in the case of serum
deprivation, both tRNAs and sitRNAs degrade rapidly, with the accumulation of tRNA being halved. Our results may provide new
insight into a novel mechanism for stressed G. lamblia to regulate gene expression globally.
Full-text · Article · Oct 2008 · Nucleic Acids Research