Differential expression of microRNAs in shrimp Marsupenaeus japonicus in response to Vibrio alginolyticus infection.

Till date numerous microRNAs (miRNAs) have been discovered from various organisms, including mammals, plants, insects, nematodes and viruses. They are known to have antiviral functions in crustaceans such as shrimp Marsupenaeus japonicas. However, little is known about the role of miRNAs against bacterial infection in this shrimp caused by Vibrio alginolyticus. We performed small RNA sequencing to characterize the differentially expressed microRNAs in V. alginolyticus challenged shrimp, in comparison to that in control uninfected shrimp, at 24 h and 48 h. In total, 55 host miRNAs were differentially expressed in response to the infection and most of these were downregulated at both the time-points. TargetScan and miRanda algorithms showed that the target genes of these down-regulated miRNAs were related to innate immune functions such as production of phenoloxidase enzyme, apoptosis and phagocytosis. Further, gene ontology analysis revealed that many immune signaling pathways were mediated by these miRNAs. This study is one of the earliest attempts at characterizing shrimp miRNAs that respond to V. alginolyticus infection, and will help unravel the miRNA pathways involved in antibacterial action in shrimp.

Anisotropic thermoelectric properties of layered compounds in SnX2 (X = S, Se): a promising thermoelectric material.

Thermoelectrics interconvert heat to electricity and are of great interest in waste heat recovery, solid-state cooling and so on. Here we assessed the potential of SnS2 and SnSe2 as thermoelectric materials at the temperature gradient from 300 to 800 K. Reflecting the crystal structure, the transport coefficients are highly anisotropic between a and c directions, in particular for the electrical conductivity. The preferred direction for both materials is the a direction in TE application. Most strikingly, when 800 K is reached, SnS2 can show a peak power factor (PF) of 15.50 µW cm(-1) K(-2) along the a direction, while a relatively low value (11.72 µW cm(-1) K(-2)) is obtained in the same direction of SnSe2. These values are comparable to those observed in thermoelectrics such as SnSe and SnS. At 300 K, the minimum lattice thermal conductivity (κmin) along the a direction is estimated to be about 0.67 and 0.55 W m(-1) K(-1) for SnS2 and SnSe2, respectively, even lower than the measured lattice thermal conductivity of Bi2Te3 (1.28 W m(-1) K(-1) at 300 K). The reasonable PF and κmin suggest that both SnS2 and SnSe2 are potential thermoelectric materials. Indeed, the estimated peak ZT can approach 0.88 for SnSe2 and a higher value of 0.96 for SnS2 along the a direction at a carrier concentration of 1.94 × 10(19) (SnSe2) vs. 2.87 × 10(19) cm(-3) (SnS2). The best ZT values in SnX2 (X = S, Se) are comparable to that in Bi2Te3 (0.8), a typical thermoelectric material. We hope that this theoretical investigation will provide useful information for further experimental and theoretical studies on optimizing the thermoelectric properties of SnX2 materials.

MiR-27a promotes hepatocellular carcinoma cell proliferation through suppression of its target gene peroxisome proliferator-activated receptor γ.

BACKGROUND: MicroRNAs (miRNAs) function as essential posttranscriptional modulators of gene expression, and are involved in a wide range of physiologic and pathologic states, including cancer. Numerous miRNAs are deregulated in hepatocellular carcinoma (HCC). This study aimed to investigate the role of miR-27a in the development of HCC. METHODS: The expression of MiR-27a was measured by quantitative real-time polymerase chain reaction (qRT-PCR). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to examine changes in the viability of HepG2, Bel-7402, Bel-7404 hepatoma cell lines associated with up-regulation or down-regulation of miR-27a. A dual-luciferase activity assay was used to verify a target gene of miR-27a. Immunohistochemistry, qRT-PCR, Western blotting analysis, and cell cycle and apoptosis flow cytometric assays were used to elucidate the mechanism by which miR-27a modulates liver cancer cell proliferation. RESULTS: The expression of miR-27a was significantly increased in HCC tissues and HepG2, Bel-7402, Bel-7404 hepatoma cell lines (P < 0.05). We also found that the down-regulation of miR-27a in HepG2 cells dramatically inhibited proliferation, blocked the G1 to S cell cycle transition and induced apoptosis (P < 0.05). In addition, miR-27a directly targeted the 3'- untranslated region of peroxisome proliferator-activated receptor γ (PPAR-γ), and ectopic miR-27a expression suppressed PPAR-γ expression on the mRNA and protein levels. The rosiglitazone-induced overexpression of PPAR-γ attenuated the effect of miR-27a in HCC cells. CONCLUSIONS: Our findings suggested that miRNA-27a promoted HCC cell proliferation by regulating PPAR-γ expression. MiR-27a may provide a potential therapeutic strategy for HCC treatment.

Reaction mechanism of CO oxidation on Cu(2)O(111): A density functional study.

The possible reaction mechanisms for CO oxidation on the perfect Cu(2)O(111) surface have been investigated by performing periodic density functional theoretical calculations. We find that Cu(2)O(111) is able to facilitate the CO oxidation with different mechanisms. Four possible mechanisms are explored (denoted as M(ER1), M(ER2), M(LH1), and M(LH2), respectively): M(ER1) is CO((gas))+O(2(ads))→CO(2(gas)); M(ER2) is CO((gas))+O(2(ads))→CO(3(ads))→O((ads))+CO(2(gas)); M(LH1) refers to CO((ads))+O(2(ads))→O((ads))+CO(2(ads)); and M(LH2) refers to CO((ads))+O(2(ads))→OOCO((ads))→O((ads))+CO(2(ads)). Our transition state calculations clearly reveal that M(ER1) and M(LH2) are both viable; but M(ER1) mechanism preferentially operates, in which only a moderate energy barrier (60.22 kJ/mol) needs to be overcome. When CO oxidation takes place along M(ER2) path, it is facile for CO(3) formation, but is difficult for its decomposition, thereby CO(3) species can stably exist on Cu(2)O(111). Of course, the reaction of CO with lattice O of Cu(2)O(111) is also considered. However, the calculated barrier is 600.00 kJ/mol, which is too large to make the path feasible. So, we believe that on Cu(2)O(111), CO reacts with adsorbed O, rather than lattice O, to form CO(2). This is different from the usual Mars-van Krevene mechanism. The present results enrich our understanding of the catalytic oxidation of CO by copper-based and metal-oxide catalysts.

Coadsorption of CO and NO on the Cu(2)O(111) surface: A periodic density functional theory study.

Coadsorption of carbon monoxide (CO) and nitric oxide (NO) on the Cu(2)O(111) surface was studied using periodic density functional theory calculations. It is interesting to find that CO+NO on Cu(2)O(111) could react to form adsorbed NCO surface species. Coadsorption of CO and NO could give rise to the formation of a O-C...N-O complex well bound to the Cu(2)O(111) surface, in which both the C-O and N-O bonds are greatly activated and the C-N bond is formed. Consequently, the reaction of CO with NO to form adsorbed NCO and CNO species may occur, for which it is disclosed that NCO formation is more possible than CNO formation both thermodynamically and kinetically. In addition, our calculations of searching transition states reveal that it is facile for NCO formation both kinetically and thermodynamically when CO+NO reaction takes place at Cu(CUS) site, and is impossible when this reaction takes places at O(vac) site. Moreover, CO(2) species cannot form when CO+NO reaction occurs at O(vac) site. Therefore, oxygen vacancy on Cu(2)O(111) does not play a positive role on CO+NO reaction to forming NCO, CNO, or CO(2) species.