Molecular insights into MYO3A kinase domain variants explain variability in both severity and progression of DFNB30 hearing impairment.

Hereditary hearing impairment (HI) is a common disease with the highest incidence among sensory defects. Several genes have been identified to affect stereocilia structure causing HI, including the unconventional myosin3A. Interestingly, we noticed that variants in MYO3A gene have been previously found to cause variable HI onset and severity. Using clinical exome sequencing, we identified a novel pathogenic variant p.(Lys50Arg) in the MYO3A kinase domain (MYO3A-KD). Previous in vitro studies supported its damaging effect as a 'kinase-dead' mutant. We further analyzed this variation through molecular dynamics which predicts that changes in flexibility of MYO3A structure would influence the protein-ATP binding properties. This Lys50Arg mutation segregated with congenital profound non-syndromic HI. To better investigate this variability, we collected previously identified MYO3A-KDs variants, p.(Tyr129Cys), p.(His142Gln) and p.(Pro189Thr), and built both wild type and mutant 3 D MYO3A-KD models to assess their impact on the protein structure and function. Our results suggest that KD mutations could either cause a congenital profound form of HI, when particularly affecting the kinase activity and preventing the auto-phosphorylation of the motor, or a late onset and progressive form, when partially or completely inactivating the MYO3A protein. In conclusion, we report a novel pathogenic variant affecting the ATP-binding site within the MYO3A-KD causing congenital profound HI. Through computational approaches we provide a deeper understanding on the correlation between the effects of MYO3A-KD mutations and the variable hearing phenotypes. To the best of our knowledge this is the first study to correlate mutations' genotypes with the variable phenotypes of DFNB30.Communicated by Ramaswamy H. Sarma.

Potassium Bromate-induced Changes in the Adult Mouse Cerebellum Are Ameliorated by Vanillin.

OBJECTIVE: The current study aimed to elucidate the effect of vanillin on behavioral changes, oxidative stress, and histopathological changes induced by potassium bromate (KBrO3), an environmental pollutant, in the cerebellum of adult mice. METHODS: The animals were divided into four groups: group 1 served as a control, group 2 received KBrO3, group 3 received KBrO3 and vanillin, and group 4 received only vanillin. We then measured behavioral changes, oxidative stress, and molecular and histological changes in the cerebellum. RESULTS: We observed significant behavioral changes in KBrO3-exposed mice. When investigating redox homeostasis in the cerebellum, we found that mice treated with KBrO3 had increased lipid peroxidation and protein oxidation in the cerebellum. These effects were accompanied by decreased Na+-K+ and Mg2+ ATPase activity and antioxidant enzyme gene expression when compared to the control group. Additionally, there was a significant increase in cytokine gene expression in KBrO3-treated mice. Microscopy revealed that KBrO3 intoxication resulted in numerous degenerative changes in the cerebellum that were substantially ameliorated by vanillin supplementation. Co-administration of vanillin blocked the biochemical and molecular anomalies induced by KBrO3. CONCLUSION: Our results demonstrate that vanillin is a potential therapeutic agent for oxidative stress associated with neurodegenerative diseases.

Effect of xylan oligosaccharides generated from corncobs on food acceptability, growth performance, haematology and immunological parameters of Dicentrarchus labrax fingerlings.

The objective of this study was to determine the effect of two levels of inclusion of xylan oligosaccharides (XOS) extracted from corncob on growth, feed utilization, immune status and disease resistance of Mediterranean sea bass (Dicentrarchus labrax) fingerlings. Specimens of 4.75 ± 0.69 g at initial density of 2.7 ± 0.13 kg/m(3) were fed during 12 weeks at 0 g kg(-1) diet, 5 g kg(-1) diet and 10 g kg(-1) diet, dietary XOS level of inclusion in a commercial sea bass diet. Feeding the fish at both XOS dietary inclusion levels significantly increased weight gain, protein efficiency ratio and feed conversion ratio. Feeding of supplemented diets to fish led to reducing mortalities after challenging with A. hydrophila. The haematological and immunological parameters were assayed in both pre-challenged and post-challenged groups. There was an increased trend in red blood corpuscles, white blood corpuscles, pack cell volume, haemoglobin (Hb %) and serum protein content in treated groups over the control as time elapsed with the feeding trials. The serum immunoglobulin level and lysozyme activity showed an increased trend in the fed groups. Histological features of the liver showed lower lipid vacuolization and regular-shaped morphology of hepatocytes around the sinusoidal spaces denoting a better utilization of dietary nutrients supported with the morphometric data. In conclusion, XOS added at a designated dose (5 g kg(-1) diet) in the diet improves growth and stimulates the immunity and makes D. labrax fingerlings more resistant to infection by A. hydrophila.

Biological Activities of xylooligosaccharides generated from garlic straw xylan by purified xylanase from Bacillus mojavensis UEB-FK.

A newly isolated Bacterium strain named UEB-FK was selected from Tunisian Sahara, exhibiting the highest clear zone on agar plates containing oat spelt xylan by staining with Congo red. On the basis of 16S rDNA sequence analysis, this strain was identified as Bacillus mojavensis. This strain produced extracellular xylanase. Xylanase from the strain was purified to homogeneity and had an apparent molecular weight of 14 kDa. The K m and V max values of the purified xylanase on oat spelt xylan were 3.85 mg/mL and 250.02 U/mg, respectively. The optimum pH and temperature for the enzyme were found to be 4.0 and 50 °C, respectively, and the enzyme exhibited significant heat stability. In addition, the enzyme was found to be stable in a wide range of pH (3-9). The main hydrolysis products yielded from garlic straw-extracted xylan were xylobiose and xylotriose. The antioxidant and antibacterial activities of xylan oligosaccharide (XOS) were investigated. As regards to the in vitro antioxidant activities, the XOS showed a important DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activity (IC50 = 0.45 mg/mL) and a high ß-carotene bleaching (IC50 = 2.2 mg/mL). Furthermore, XOS had a high antimicrobial activity against Klebsiella pneumoniae, Enterococcus faecalis, Bacillus thuringiensis, and Pseudomonas aeruginosa.