Whole Exome Sequencing Identifies Mutations in Usher Syndrome Genes in Profoundly Deaf Tunisian Patients

Usher syndrome (USH) is an autosomal recessive disorder characterized by combined deafness-blindness. It accounts for about 50% of all hereditary deafness blindness cases. Three clinical subtypes (USH1, USH2, and USH3) are described, of which USH1 is the most severe form, characterized by congenital profound deafness, constant vestibular dysfunction, and a prepubertal onset of retinitis pigmentosa. We performed whole exome sequencing in four unrelated Tunisian patients affected by apparently isolated, congenital profound deafness, with reportedly normal ocular fundus examination. Four biallelic mutations were identified in two USH1 genes: a splice acceptor site mutation, c.2283-1G>T, and a novel missense mutation, c.5434G>A (p.Glu1812Lys), in MYO7A, and two previously unreported mutations in USH1G, i.e. a frameshift mutation, c.1195_1196delAG (p.Leu399Alafs*24), and a nonsense mutation, c.52A>T (p.Lys18*). Another ophthalmological examination including optical coherence tomography actually showed the presence of retinitis pigmentosa in all the patients. Our findings provide evidence that USH is under-diagnosed in Tunisian deaf patients. Yet, early diagnosis of USH is of utmost importance because these patients should undergo cochlear implant surgery in early childhood, in anticipation of the visual loss.     

Role for Rab10 in Methamphetamine-Induced Behavior

Lipid rafts are specialized, cholesterol-rich membrane compartments that help to organize transmembrane signaling by restricting or promoting interactions with subsets of the cellular proteome. The hypothesis driving this study was that identifying proteins whose relative abundance in rafts is altered by the abused psychostimulant methamphetamine would contribute to fully describing the pathways involved in acute and chronic effects of the drug. Using a detergent-free method for preparing rafts from rat brain striatal membranes, we identified density gradient fractions enriched in the raft protein flotillin but deficient in calnexin and the transferrin receptor, markers of non-raft membranes. Dopamine D1- and D2-like receptor binding activity was highly enriched in the raft fractions, but pretreating rats with methamphetamine (2 mg/kg) once or repeatedly for 11 days did not alter the distribution of the receptors. LC-MS analysis of the protein composition of raft fractions from rats treated once with methamphetamine or saline identified methamphetamine-induced changes in the relative abundance of 23 raft proteins, including the monomeric GTP-binding protein Rab10, whose abundance in rafts was decreased 2.1-fold by acute methamphetamine treatment. Decreased raft localization was associated with a selective decrease in the abundance of Rab10 in a membrane fraction that includes synaptic vesicles and endosomes. Inhibiting Rab10 activity by pan-neuronal expression of a dominant-negative Rab10 mutant in Drosophila melanogaster decreased methamphetamine-induced activity and mortality and decreased caffeine-stimulated activity but not mortality, whereas inhibiting Rab10 activity selectively in cholinergic neurons had no effect. These results suggest that activation and redistribution of Rab10 is critical for some of the behavioral effects of psychostimulants.     

Deconstructing the DGAT1 Enzyme: Membrane Interactions at Substrate Binding Sites

Diacylglycerol acyltransferase 1 (DGAT1) is a key enzyme in the triacylglyceride synthesis pathway. Bovine DGAT1 is an endoplasmic reticulum membrane-bound protein associated with the regulation of fat content in milk and meat. The aim of this study was to evaluate the interaction of DGAT1 peptides corresponding to putative substrate binding sites with different types of model membranes. Whilst these peptides are predicted to be located in an extramembranous loop of the membrane-bound protein, their hydrophobic substrates are membrane-bound molecules. In this study, peptides corresponding to the binding sites of the two substrates involved in the reaction were examined in the presence of model membranes in order to probe potential interactions between them that might influence the subsequent binding of the substrates. Whilst the conformation of one of the peptides changed upon binding several types of micelles regardless of their surface charge, suggesting binding to hydrophobic domains, the other peptide bound strongly to negatively-charged model membranes. This binding was accompanied by a change in conformation, and produced leakage of the liposome-entrapped dye calcein. The different hydrophobic and electrostatic interactions observed suggest the peptides may be involved in the interactions of the enzyme with membrane surfaces, facilitating access of the catalytic histidine to the triacylglycerol substrates.     

Separate and overlapping specificities in rheumatoid arthritis antibodies binding to citrulline- and homocitrulline-containing peptides related to type I and II collagen telopeptides

IntroductionOur objective was to find out if there are antibodies binding to homocitrulline-containing type I and II collagen carboxyterminal telopeptides in sera of patients with rheumatoid arthritis (RA), and if these antibodies cross-react with citrulline and homocitrulline in the same peptide sequence.MethodsA total of 72 RA and 72 control sera were analyzed for binding using enzyme-linked immunosorbent assay to citrulline- or homocitrulline-containing type I and II collagen carboxyterminal telopeptides, as well as to cyclic citrullinated peptide (CCP) and to mutated citrullinated vimentin (MCV). Specificities of the antibodies were tested using inhibition-ELISA.ResultsOf the RA sera, 39 (54%) and 41 (57%) were positive for binding to CCP and MCV, respectively. Further, 34 (47%) and 30 (42%) of the patients had specific antibodies binding to and being inhibited by citrulline-containing type I collagen telopeptides and by citrulline-containing type II collagen carboxyterminal telopeptides, respectively. The corresponding figures regarding homocitrulline-containing type I and homocitrulline-containing type II collagen telopeptides were 16 (22%) and 14 (19%). Most of the patients, who were seropositive for citrullinated peptides, showed binding in multiple assays. A total of 10 (14%) RA patients were positive for all the tested peptide pairs, while 28 (39%) of them had antibodies that contained overlapping specifities between citrulline and homocitrulline in the same peptide sequence.ConclusionsAntibodies to both citrulline and homocitrulline containing type I and II collagen telopeptides can be found in sera of RA patients. These antibodies are not constant from one RA patient to another, but contain separate or overlapping specificities within the same peptide sequence varying between individuals. Our results suggest some relationship between citrulline and homocitrulline-recognizing antibodies, since homocitrulline antibodies exist mainly in individuals seropositive to anti-CCP and anti-MCV.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0515-z) contains supplementary material, which is available to authorized users.     

Effects of Delphinidin on Pathophysiological Signs of Nucleus Basalis of Meynert Lesioned Rats as Animal Model of Alzheimer Disease

Neurochemical Research - Alzheimer’s disease (AD) is an advanced neurodegenerative disorder greatly accompanied by cognitive deficits, oxidative stress, inflammation, amyloid plaques...     

Effect of Silicon and Phosphate-Solubilizing Bacteria on Improved Phosphorus (P) Uptake Is Not Specific to Insoluble P-Fertilized Sorghum (Sorghum bicolor L.) Plants

In the research, the single-and dual effects of phosphate-solubilizing bacteria (PSB) (B0, Pseudomonas sp. FA1, and Bacillus simplex UT1) and silicon (Si) (0, 150, 300, and 600 mg kg⁻¹ used as silicic acid) on P uptake by sorghum (Sorghum bicolor L.) plant fertilized with soluble or insoluble P (rock phosphate—RP) were studied via a perlite-potted experiment. Moreover, the effects of various treatments on morphological (shoot and root dry weight), nutritional (the uptake of Si and K) and physiological parameters (activity of catalase, superoxide dismutase, and peroxidase enzymes) of this plant were also measured. When grown in RP-fertilized medium compared with those grown in soluble P-fertilized medium, both shoot biomass and root biomass of sorghum plants were noticeably diminished. The PSB strains and Si levels independently improved all the aforementioned parameters. Use of Si and PSB strains to sorghum plants grown in soluble P or insoluble P medium significantly augmented P use efficiency. Silicon not only augmented the uptake of P from sparingly soluble-P source (RP), but also augmented uptake of P from water-soluble P source. Both B. simplex UT1 and Pseudomonas sp. FA1 indicated a meaningful betterment in sorghum plant dry matter and uptake of P (and K and Si) under both soluble and insoluble P fertilization conditions with Pseudomonas sp. FA1 being more efficacious than B. simplex UT1. But, the dual use of the PSB with Si resulted in the greatest increase in sorghum plant P uptake and other measured growth indices. Application of 600 mg Si kg⁻¹ and Pseudomonas sp. FA1 significantly augmented the P shoot concentration of sorghum plant fertilized with RP to an sufficient level (> 0.3%) in the range of P-fertilized sorghum plants. Therefore, in addition to PSB utilization, Si should be considered as soil amendment in agricultural soils inadequate in plant-available Si as a means of sustainable agriculture with respect to possible savings of scarce P resources.

     

The Effects of Supplementation with Probiotic on Biomarkers of Oxidative Stress in Adult Subjects: a Systematic Review and Meta-analysis of Randomized Trials

Probiotics and Antimicrobial Proteins - Previous studies have supposed that probiotic supplementation led to a positive effect on different health outcomes. Furthermore, several studies indicated...     

Detecting the Quantity of Acrylamide in Potato Chips Utilizing CdTe Surface Functionalized Quantum Dots with Fluorescence Spectroscopy

International Journal of Peptide Research and Therapeutics - According to the classification of the International Agency for Research on Cancer (IARC), acrylamide is a compound in “probably...     

A mini review on molecularly imprinted polymer based halloysite nanotubes composites: innovative materials for analytical and environmental applications

Reviews in Environmental Science and Bio/Technology - Halloysite nanotubes (HNTs) are of importance for the elimination of various kinds of molecules from complex matrix due to their outstanding...