Caseyyu3130

We have reported previously that a missense mutation in the mitochondrial fission gene Dynamin-related protein 1 (Drp1) underlies the Python mouse model of monogenic dilated cardiomyopathy. The aim of this study was to investigate the consequences of the C452F mutation on Drp1 protein function and to define the cellular sequelae leading to heart failure in the Python monogenic dilated cardiomyopathy model. We found that the C452F mutation increased Drp1 GTPase activity. The mutation also conferred resistance to oligomer disassembly by guanine nucleotides and high ionic strength solutions. In a mouse embryonic fibroblast model, Drp1 C452F cells exhibited abnormal mitochondrial morphology and defective mitophagy. Mitochondria in C452F mouse embryonic fibroblasts were depolarized and had reduced calcium uptake with impaired ATP production by oxidative phosphorylation. In the Python heart, we found a corresponding progressive decline in oxidative phosphorylation with age and activation of sterile inflammation. As a corollary, enhancing autophagy by exposure to a prolonged low-protein diet improved cardiac function in Python mice. In conclusion, failure of Drp1 disassembly impairs mitophagy, leading to a downstream cascade of mitochondrial depolarization, aberrant calcium handling, impaired ATP synthesis, and activation of sterile myocardial inflammation, resulting in heart failure.RNA-based genetic regulation is exemplified by metabolite-binding riboswitches that modulate gene expression through conformational changes. Crystal structures show that the Escherichia coli btuB riboswitch contains a kissing loop interaction that is in close proximity to the bound ligand. To analyze the role of the kissing loop interaction in the riboswitch regulatory mechanism, we used RNase H cleavage assays to probe the structure of nascent riboswitch transcripts produced by the E. coli RNA polymerase. By monitoring the folding of the aptamer, kissing loop, and riboswitch expression platform, we established the conformation of each structural component in the absence or presence of bound adenosylcobalamin. We found that the kissing loop interaction is not essential for ligand binding. However, we showed that kissing loop formation improves ligand binding efficiency and is required to couple ligand binding to the riboswitch conformational changes involved in regulating gene expression. These results support a mechanism by which the btuB riboswitch modulates the formation of a tertiary structure to perform metabolite sensing and regulate gene expression.Fe(III) storage by ferritin is an essential process of the iron homeostasis machinery. It begins by translocation of Fe(II) from outside the hollow spherical shape structure of the protein, which is formed as the result of self-assembly of 24 subunits, to a di-iron binding site, the ferroxidase center, buried in the middle of each active subunit. The pathway of Fe(II) to the ferroxidase center has remained elusive, and the importance of self-assembly for the functioning of the ferroxidase center has not been investigated. Here we report spectroscopic and metal ion binding studies with a mutant of ferritin from Pyrococcus furiosus (PfFtn) in which self-assembly was abolished by a single amino acid substitution. We show that in this mutant metal ion binding to the ferroxidase center and Fe(II) oxidation at this site was obliterated. However, metal ion binding to a conserved third site (site C), which is located in the inner surface of each subunit in the vicinity of the ferroxidase center and is believed to be the path for Fe(II) to the ferroxidase center, was not disrupted. These results are the basis of a new model for Fe(II) translocation to the ferroxidase center self-assembly creates channels that guide the Fe(II) ions toward the ferroxidase center directly through the protein shell and not via the internal cavity and site C. The results may be of significance for understanding the molecular basis of ferritin-related disorders such as neuroferritinopathy in which the 24-meric structure with 432 symmetry is distorted.Streptococcus pneumoniae is an important human pathogen that causes a range of disease states. Sialidases are important bacterial virulence factors. There are three pneumococcal sialidases NanA, NanB, and NanC. NanC is an unusual sialidase in that its primary reaction product is 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en, also known as DANA), a nonspecific hydrolytic sialidase inhibitor. The production of Neu5Ac2en from α2-3-linked sialosides by the catalytic domain is confirmed within a crystal structure. A covalent complex with 3-fluoro-β-N-acetylneuraminic acid is also presented, suggesting a common mechanism with other sialidases up to the final step of product formation. A conformation change in an active site hydrophobic loop on ligand binding constricts the entrance to the active site. In addition, the distance between the catalytic acid/base (Asp-315) and the ligand anomeric carbon is unusually short. These features facilitate a novel sialidase reaction in which the final step of product formation is direct abstraction of the C3 proton by the active site aspartic acid, forming Neu5Ac2en. NanC also possesses a carbohydrate-binding module, which is shown to bind α2-3- and α2-6-linked sialosides, as well as N-acetylneuraminic acid, which is captured in the crystal structure following hydration of Neu5Ac2en by NanC. Overall, the pneumococcal sialidases show remarkable mechanistic diversity while maintaining a common structural scaffold.Siglec-1 (sialoadhesin, CD169) is a surface receptor on human cells that mediates trans-enhancement of HIV-1 infection through recognition of sialic acid moieties in virus membrane gangliosides. Here, we demonstrate that mouse Siglec-1, expressed on the surface of primary macrophages in an interferon-α-responsive manner, captures murine leukemia virus (MLV) particles and mediates their transfer to proliferating lymphocytes. The MLV infection of primary B-cells was markedly more efficient than that of primary T-cells. The major structural protein of MLV particles, Gag, frequently co-localized with Siglec-1, and trans-infection, primarily of surface-bound MLV particles, efficiently occurred. To explore the role of sialic acid for MLV trans-infection at a submolecular level, we analyzed the potential of six sialic acid precursor analogs to modulate the sialylated ganglioside-dependent interaction of MLV particles with Siglec-1. Biosynthetically engineered sialic acids were detected in both the glycolipid and glycoprotein fractions of MLV producer cells. MLV released from cells carrying N-acyl-modified sialic acids displayed strikingly different capacities for Siglec-1-mediated capture and trans-infection; N-butanoyl, N-isobutanoyl, N-glycolyl, or N-pentanoyl side chain modifications resulted in up to 92 and 80% reduction of virus particle capture and trans-infection, respectively, whereas N-propanoyl or N-cyclopropylcarbamyl side chains had no effect. In agreement with these functional analyses, molecular modeling indicated reduced binding affinities for non-functional N-acyl modifications. Thus, Siglec-1 is a key receptor for macrophage/lymphocyte trans-infection of surface-bound virions, and the N-acyl side chain of sialic acid is a critical determinant for the Siglec-1/MLV interaction.Terbufos (S-t-butylthiomethyl-O,O-diethyl phosphorodithioate) is a highly toxic organophosphate which is extensively used as an insecticide and nematicide. Chronic exposure to terbufos causes neuronal injury and predisposes to neurodegenerative diseases. Accumulating evidence has shown that the exposure to terbufos, as an occupational risk factor, may also cause reproductive disorders. However, the exact mechanisms of reproductive toxicity remain unclear. The present study aimed to investigate the toxic effect of terbufos on testicular cells and to explore the mechanism of toxicity on a cellular level. The cytotoxic effects of terbufos on mouse immortalized spermatogonia (GC-1), spermatocytes (GC-2), Leydig (TM3), and Sertoli (TM4) cell lines were assessed by MTT assays, caspase activation, flow cytometry, TUNEL assay, Western blot, and cell cycle analysis. The exposure to different concentrations of terbufos ranging from 50 to 800 μM for 6 h caused significant death in all the used testicular cell lines. Terbufos increased reactive oxygen species (ROS) production, reduced mitochondrial membrane potential, and initiated apoptosis, which was confirmed by a dose-dependent increase in the number of TUNEL-positive apoptotic cells. Blocking ROS production by N-acetyl cysteine (NAC) protected GC-1 cells from terbufos-induced cell death. The results demonstrated that terbufos induces ROS, apoptosis, and DNA damage in testicular cell lines and it should be considered potentially hazardous to testis. Together, this study provided potential molecular mechanisms of terbufos-induced toxicity in testicular cells and suggests a possible protective measure. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31 1888-1898, 2016.

Oral health-related quality of life (OHRQoL) measures should be tested for responsiveness to change if they are to be used as outcomes in randomized clinical trials.

To assess the responsiveness of the Brazilian ECOHIS (B-ECOHIS) to dental treatment of dental caries.

One hundred parents of 3- to 5-year-old children completed the B-ECOHIS prior to their children's treatment and 7-14days after completion of treatment. The post-treatment questionnaire also included a global transition judgment that assessed parent's perceptions of change in their children's oral health following treatment. Change scores, longitudinal construct validity, standardized effect sizes (ES) and standardized response mean (SRM) were calculated.

Improvements in children's oral health after treatment were reflected in mean pre- and post-treatment B-ECOHIS scores. They declined considerably significantly from 17.4 to 1.6 (P<0.0001), as did the individual domain scores (P<0.0001). There were significant differences in the pre- and post-treatment scores of children who reported little improvement (P<0.0001) as well as in those who reported large improvements (P<0.0001). The ES and SRM based on change scores mean for total scores and for categories of global transitions judgments were large.

Dental treatment resulted in significant improvement of the preschool children's OHRQoL. The B-ECOHIS is responsive.

Dental treatment resulted in significant improvement of the preschool children's OHRQoL. The B-ECOHIS is responsive.The raw materials used to produce bioethanol mostly are food crops, which has led to conflicts on food security. It is, therefore, recommended the gradual replacement for second generation substrates such as lignocellulosic materials. Herein, cellulolytic bacteria were isolated from the gut content of native larvae from Lepidoptera, Coleoptera, and adults of Isoptera. Few environmental samples from the pulp and paper feedstock were also assessed. A total of 233 isolates were obtained using enrichment cultures and classic criteria. Interestingly, several halo-forming colonies were found to be bacterial consortia that presented difficulties to take apart the microbial members. Those pure isolates which hydrolyzed cellulose in larger extend (45 strains) were selected and identified by means of 16S rRNA sequence analysis. Firmicutes was the prevalent phylum (62.2%) being Bacillus spp. the most frequent genus, while Paenibacillus, Brevibacillus, Cohnella, and Staphylococcus species were less frequent. The phylum Actinobacteria (6.