Enhancing effect of cobalt phthalocyanine dispersion on electrocatalytic reduction of CO2 towards methanol.

This paper focuses on enhancing the performance of electrocatalytic CO2 reduction reaction (CO2RR) by improving the dispersion of cobalt phthalocyanine (CoPc), especially for the methanol formation with multi-walled carbon nanotubes (CNTs) as a support. The promising CNTs-supported CoPc hybrid was prepared based on ball milling technique, and the surface morphology was characterized by means of those methods such as scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectra (XPS). Then, the synergistic effect of CNTs and ball milling on CO2RR performance was analyzed by those methods of cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), gas chromatography (GC), and proton nuclear magnetic resonance spectroscopy (1HNMR). Subsequently, the reduction mechanism of CO2 on ball-milled CoPc/CNTs was revealed based on the DFT calculations. The results showed that the electrocatalyst CoPc/CNTs hybrid prepared with sonication exhibited a conversion efficiency of CO2 above 60% at -1.0 V vs. RHE, accompanied by the Faradaic efficiencies of nearly 50% for CO and 10% for methanol, respectively. The addition of CNTs as the support improved the utilization efficiency of CoPc and reduced the transfer resistance of species and electrons. Then the ball-milling method further improved the dispersion of CoPc on CNTs, which resulted in the fact that the methanol efficiency was raised by 6% and partial current density was increased by nearly 433%. The better dispersion of CoPc on CNTs adjusted the reduction pathway of CO2 and resulted in the enhancement of methanol selectivity and catalytic activity of CO2. The probable pathway for methanol production was proposed as CO2 → *CO2- → *COOH → *CO → *CHO → *CH2O → *OCH3 → CH3OH. This suggests the significance of the ball-milling method during the preparation of better supported catalysts for CO2RR towards those high-valued products.

Djrho2 is involved in regeneration of visual nerves in Dugesia japonica.

The freshwater planarian is a powerful animal model for studying regeneration and stem cell activity in vivo. During regeneration, stem cells (neoblasts in planarian) migrated to the wounding edge to re-build missing parts of the body. However, proteins involved in regulating cell migration during planarian regeneration have not been studied extensively. Here we report two small GTPase genes (Djrho2 and Djrho3) of Dugesia japonica (strain Pek-1). In situ hybridization results indicated that Djrho2 was expressed throughout the body with the exception of the pharynx region while Djrho3 was specifically expressed along the gastro-vascular system. Djrho2 was largely expressed in neoblasts since its expression was sensitive to X-ray irradiation. In Djrho2-RNAi planarians, smaller anterior blastemas were observed in tail fragments during regeneration. Consistently, defective regeneration of visual nerve was detected by immunostainning with VC-1 antibody. These results suggested that Djrho2 is required for proper anterior regeneration in planairan. In contrast, no abnormality was observed after RNAi of Djrho3. We compared protein compositions of control and Djrho2-RNAi planarians using an optimized proteomic approach. Twenty-two up-regulated and 26 de-regulated protein spots were observed in the two-dimensional electrophoresis gels, and 17 proteins were successfully identified by Mass Spectrometry (MS) analysis. Among them, 6 actin-binding or cytoskeleton-related proteins were found de-expressed in Djrho2-RNAi animals, suggesting that abnormal cytoskeleton assembling and cell migration were likely reasons of defected regeneration.

A small scale expression screen identifies tissue specific markers in the Dugesia japonica strain Pek-1.

Freshwater planaria has tremendous capacity to reform the missing part of the body and therefore is considered as one of the most important model organism for regeneration study. At present, Schmidtea mediterranea and Dugesia japonica are the two major species utilized for laboratory manipulations. Dugesia japonica flatworms are widely distributed in the Far East including Cherry Valley region in the north-west area of Beijing, China. We reported here the establishment of an asexual Dugesia japonica strain Pek-1, as a suitable system for regeneration study. Using morphological, karyotypical as well as phylogenetic analyses, we confirmed that these flatworms indeed belonged to Dugesia japonica. We went on to show that the commonly used in situ probes and immunohistochemistry reagents and protocols were applicable to the Pek-1 strain. Using this strain, we carried out small scale analysis on EST, RNAi and gene expression. We identified 193 unique EST sequences and 65 of them had not been reported in planarian. By RNAi analysis, we showed that 48 genes, when down-regulated individually, had no effect on regeneration. Furthermore, we identified 3 groups of tissue specific expressing genes that were useful for cell lineage analysis. We concluded that the Dugesia japonica Pek-1 strain could be another suitable animal model to regeneration research.

Complete functional segregation of planarian beta-catenin-1 and -2 in mediating Wnt signaling and cell adhesion.

beta-Catenin is a bifunctional protein participating in both cell adhesion and canonical Wnt signaling. In cell adhesion, it bridges the transmembrane cadherin and the actin-binding protein alpha-catenin and is essential for adherens junction formation, whereas in canonical Wnt signaling, it shuttles between the cytosol and nucleus and functions as an essential transcriptional activator. Schmidtea mediterranea beta-catenin-1 was identified as a determinant of antero-posterior polarity during body regeneration by mediating Wnt signaling. Here we show that S. mediterranea beta-catenin-2 is specifically expressed in epithelial cells in the gut and pharynx, where it has a putative role in mediating cell adhesion. We show evidence that planarian beta-catenin-1 and -2 have distinct biochemical properties. beta-Catenin-1 can interact with the components of the canonical Wnt signaling pathway but not with alpha-catenin, whereas beta-catenin-2 interacts with cell adhesion molecules, including E-cadherin and alpha-catenin, but not with Wnt signaling components. Consistent with their specific function, beta-catenin-1 is a potent transcriptional activator, whereas beta-catenin-2 has no transcriptional activity. Protein sequence alignment also indicates that the planarian beta-catenin-1 and -2 retain distinct critical residues and motifs, which are in agreement with the differences in their biochemical properties. At last, phylogenetic analysis reveals a probable Platyhelminthes- specific structural and functional segregation from which the monofunctional beta-catenins evolved. Our results thus identify the first two monofunctional beta-catenins in metazoans.