ABSTRACT
The developmental activation of the corpus luteum (CL) structurally and functionally is critical for the temporally regulated establishment, maintenance, and termination of pregnancy in rats. In this study, we have investigated the possible involvement of autophagy in the regulation of the CL during pregnancy in rats. The expression ratio of microtubule-associated protein light chain 3 (LC3)-II/-I, a widely used indicator of autophagic activity, in the CL remained relatively stable until day 15 of pregnancy. Subsequently, it progressively increased until day 21, and then declined until day 3 postpartum. This fluctuation was closely associated with the tissue weight of the CL rather than progesterone (P4) production activity. Light and electron microscopy revealed the presence of immunoreactive LC3 aggregates and irregularly shaped autolysosome-like microstructures in the cytoplasm of luteal cells during late pregnancy. Notably, a bolus intrabursal injection of the autophagy inhibitor bafilomycin A1 on day 15 of pregnancy resulted in a significant reduction in luteal cell size and disrupted the normal alteration of circulating P4 levels. Consequently, treatment with this inhibitor increased the likelihood of the varied timing (both advanced and delayed) of delivery and led to reduced body weight in neonates when compared with the vehicle-treated control group. Our findings suggest that autophagy in the rat CL contributes to luteal tissue growth, influences P4 production, and thereby fine-tunes the regulation of gestation length in rats.
ABSTRACT
The chemical functionalization of nano-carbon materials such as single-walled carbon nanotubes (SWNTs) and graphene by metal complexes has attracted much attention due to the multitude of potential applications in efficient energy-conversion and -storage devices. The solubilization and single-chirality separation of SWNTs by surface modifications is a useful approach to manipulate SWNTs in the liquid phase. In this study, several Ru and Fe complexes containing two terminal quadruple hydrogen-bonded (H-bonded) ureidopyrimidinedione (UPy) groups were synthesized (Ru-1, Ru-UPy, and Fe-UPy) to form H-bonded supramolecular polymers by self-association. In order to control the solubility of these complexes in nonpolar solvents, Ru-UPy and Fe-UPy were endowed with long alkyl side chain groups in the coordinated 2,6-bis(benzimidazol-2-yl)pyridine ligand, while Ru-1 and Ru-2 do not contain such long alkyl chain groups. AFM measurements revealed that Ru-1, Ru-UPy, and Fe-UPy form a fiber-like network morphology on HOPG surfaces, arising from the H-bonded aggregation. However, only Ru-UPy and Fe-UPy are able to solubilize SWNTs effectively upon simple sonication in chlorobenzene. After the solubilization of a CoMoCAT® SWNT in chlorobenzene using Ru-UPy or Fe-UPy, UV-Vis-NIR spectra showed sharp peaks at 996 and 1150 nm, which were attributed to (6, 5) and (7, 6)-SWNTs. The Raman spectra of the solubilized SWNTs revealed peaks that were attributed to the radial breathing mode (RBM), which suggests an enrichment of semiconducting SWNTs, i.e., Ru-UPy and Fe-UPy are able to selectively solubilize semiconducting SWNTs. Cyclic voltammograms of films of SWNTs covered with Ru-UPy or Fe-UPy on ITO electrodes showed a well-defined adsorbed Ru(ii/iii) or Fe(ii/iii) wave. Upon addition of acid, the redox response from the adsorbed H-bonded Ru-UPy and Fe-UPy disappeared and only SWNTs were left on the ITO electrode. Moreover, the Ru-UPy/SWNT and Fe-UPy/SWNT hybrids exhibited non-linear I-V characteristics.
ABSTRACT
We synthesized three types of binuclear Ru complexes (1-3) that contain pyrene anchors for the adsorption of 1-3 onto nanocarbon materials via noncovalent π-π interactions, in order to investigate their adsorption onto and their desorption from highly ordered pyrolytic graphite (HOPG). The adsorption saturation for 1 (6.22 pmol/cm2), 2 (2.83 pmol/cm2), and 3 (3.53 pmol/cm2) on HOPG was obtained from Langmuir isotherms. The desorption rate from HOPG electrodes decreased in the order 3 (2.4 × 10-5 s-1) > 2 (1.4 × 10-5 s-1) â« 1 (1.8 × 10-6 s-1). These results indicate that the number of pyrene anchors and their position of substitution in such complexes strongly affect the desorption behavior. However, neither the free energy of adsorption (ΔGads) nor the heterogeneous electron-transfer rate (kET) showed any significant differences among 1-3, albeit that the surface morphologies of the modified HOPG substrates showed domain structures that were characteristic for each Ru complex. In the case of 3, the average height changed from â¼2 to â¼4 nm upon increasing the concentration of the solution of 3 that was used for the surface modification. In contrast, the height for 1 and 2 remained constant (1.5-2 nm) upon increasing the concentration of the complexes in the corresponding solutions. While the molecular orientation of the Ru-Ru axis of 3 relative to the HOPG surface normal changed from parallel to perpendicular, the Ru-Ru axis in 1 and 2 remained parallel, which leads to an increased stability of 1 and 2.
ABSTRACT
DNA methylation in promoter regions represses gene expression and is copied over mitotic divisions by Dnmt1. Dnmt1 activity is regulated by its replication foci targeting sequence (RFTS) domain which masks the catalytic pocket. It has been shown that Dnmt1 activity on unmethylated DNA is inhibited in nucleosome cores. In the present study, we aimed to assess the effect of nuclesome formation on maintenance methylation at single CpG resolution. We show that Dnmt1 fully methylates naked linker DNA in dinucleosomes, whereas maintenance methylation was repressed at all CpG sites in nucleosome core particles. Deletion of RFTS partly released obstruction of Dnmt1 activity in core particles. Histone H3 tail peptides inhibited Dnmt1 in an RFTS-dependent manner and repression was modulated by acetylation or methylation. We propose a novel function of RFTS to regulate Dnmt1 activity in nucleosomes.
