As a non-invasive genetic method, eDNA based approaches have become an important component of ecologists' and environmental managers' toolkits for biomonitoring in conservation and an increasingly... Show moreAs a non-invasive genetic method, eDNA based approaches have become an important component of ecologists' and environmental managers' toolkits for biomonitoring in conservation and an increasingly important source of ecological knowledge. This thesis focuses on aquatic eDNA based approaches beyond detections of species presence by 1) enhancing the knowledge of the characteristics of aquatic eDNA particle size distribution (PSD), 2) exploring the possibility of eDNA analysis in physiological investigation and 3) performing functional gene analysis across species. Aquatic eDNA PSD changes with degradation interacting with environmental factors and species. This knowledge supports the capability of eDNA PSD analysis in assessing false- and real-positive of species presence, as well as contributing to abundance assessment and guiding sampling strategy development when using eDNA based approaches. eDNA methylation varies between life stages, and supports life stage evaluations, and brings up the possibility of using eDNA methylation analysis in assessing physiological information. eDNA based approaches support functional gene analysis across species. Functional gene analysis promotes investigating ARGs pollution and the interaction of pollution between different types of agricultural regions. Thanks to the continuously increasing insights on environment-related gene function and expression level, it becomes potentially possible to use eDNA functional gene (and methylation) analysis to evaluate environmental changes. Overall, this thesis contributes to expanding the application of aquatic eDNA based approaches beyond detections of species presence, and provides efficient and non-invasive approaches for biomonitoring and ecological assessments. Show less
BackgroundHearing loss is one of the most prevalent disabilities worldwide, and has a significant impact on quality of life. The adult-onset type of the condition is highly heritable but the... Show moreBackgroundHearing loss is one of the most prevalent disabilities worldwide, and has a significant impact on quality of life. The adult-onset type of the condition is highly heritable but the genetic causes are largely unknown, which is in contrast to childhood-onset hearing loss.MethodsFamily and cohort studies included exome sequencing and characterisation of the hearing phenotype. Ex vivo protein expression addressed the functional effect of a DNA variant.ResultsAn in-frame deletion of 12 nucleotides in RIPOR2 was identified as a highly penetrant cause of adult-onset progressive hearing loss that segregated as an autosomal dominant trait in 12 families from the Netherlands. Hearing loss associated with the deletion in 63 subjects displayed variable audiometric characteristics and an average (SD) age of onset of 30.6 (14.9) years (range 0-70 years). A functional effect of the RIPOR2 variant was demonstrated by aberrant localisation of the mutant RIPOR2 in the stereocilia of cochlear hair cells and failure to rescue morphological defects in RIPOR2-deficient hair cells, in contrast to the wild-type protein. Strikingly, the RIPOR2 variant is present in 18 of 22 952 individuals not selected for hearing loss in the Southeast Netherlands.ConclusionCollectively, the presented data demonstrate that an inherited form of adult-onset hearing loss is relatively common, with potentially thousands of individuals at risk in the Netherlands and beyond, which makes it an attractive target for developing a (genetic) therapy. Show less
Toxicity of ZnO nanoparticles (NPs) are often related to the release of Zn2+ ions due to their dissolution. Studies also suggest that the toxicity of ZnO NPs cannot be solely explained by the... Show moreToxicity of ZnO nanoparticles (NPs) are often related to the release of Zn2+ ions due to their dissolution. Studies also suggest that the toxicity of ZnO NPs cannot be solely explained by the release of Zn2+ ions; however, there is a lack of direct evidence of ZnO particulate effects. This study compared the acute toxicity of ZnO NPs and ZnSO4 following intranasal exposure using a combination of metallomics and metabolomics approaches. Significant accumulation of Zn in the liver was only found in the ZnO NP treatment, with 29% of the newly accumulated Zn in the form of ZnO as revealed by X-ray fine structure spectroscopy (XAFS). This is the first direct evidence suggesting the persistence of ZnO NPs in liver upon intranasal exposure. Although both ZnO NPs and ZnSO4 altered the metabolite profiles, with some overlaps and considerable specificity, of both liver and plasma samples, more and distinct metabolites in the liver and opposite effects in the plasma were altered by ZnO NPs compared with ZnSO4, consistent with no accumulation of Zn detected in liver from ZnSO4. Specifically, a large number of antioxidant-related compounds and energetic substrates were exclusively elevated in the liver of ZnO NP-treated animals. These findings provided direct evidence that persistence of ZnO NPs induced particle-specific effects on the antioxidant systems and energy metabolism pathways. Show less
