Biology subjects

Clarkson, C.

Publications and source records attributed to Clarkson, C..

4 recordsLinked to original sources

bioRxiv2024

A candidate reference method for the quantification of α-synuclein in cerebrospinal fluid using an SI traceable primary calibrator and multiple reaction monitoring

Objectives-synuclein aggregation is an indicator of neurodegenerative diseases such as Parkinsons disease (PD) and recent advances have suggested that this protein could serve as a potential biomarker. It has been indicated that soluble and oligomeric -synuclein in biological fluids could have diagnostic applications for PD. Clinical laboratories currently rely on antibody-based assays to detect -synuclein. These assays have limited specificity, low sensitivity and poor inter-lab reproducibility, which prevents the validation of -synuclein as a biomarkers. This study aims to fill the unmet need for the standardisation of clinical measurements for -synuclein. MethodsWe report the first candidate reference method for -synuclein, using an SI traceable primary calibrator for -synuclein and isotope dilution mass spectrometry. The primary calibrator was traceably quantified utilising a combination of amino acid analysis and nuclear magnetic resonance. A targeted sample clean-up procedure involving a non-denaturing Lys-C digestion and solid-phase extraction allowed for the sensitive detection of multiple proteotypic -synuclein peptides in cerebrospinal fluid (CSF) samples. ResultsThe candidate reference method procedure showed linearity across three orders of magnitude, covering the physiological levels of -synuclein in CSF (LOQ = 0.1 ng/g). The method was used to quantify a cohort of CSF samples and the measurements were correlated with immunoassay-based quantifications. ConclusionsThe SI traceable quantification of -synuclein in complex biological matrices means that the role of this protein can be further elucidated in synucleinopathies. This candidate reference method would lead to the harmonisation of -synuclein measurements, which may allow for development of high throughput clinical tests.

biochemistry↗

bioRxiv2023

Loss of the mitochondrial citrate carrier, SLC25A1/CIC disrupts embryogenesis via 2-Hydroxyglutarate

Germline inactivating mutations of the SLC25A1 gene contribute to various human developmental disorders, including combined D/L-2-hydroxyglutaric aciduria (D/L-2HGA), a severe systemic syndrome characterized by the accumulation of both enantiomers of 2-hydroxyglutaric acid (2HG). The mechanisms by which SLC25A1 deficiency leads to this disease and the role of 2HG are unclear and no therapies exist. We now show that mice lacking both Slc25a1 alleles display a spectrum of alterations that resemble human D/L-2HGA. Mechanistically, SLC25A1 loss results in a proliferation defect and activates two distinct senescence pathways, oncogene-induced senescence (OIS) and mitochondrial dysfunction-induced senescence (MiDAS), both involving the p53 tumor suppressor and driven by two discernible signals: the accumulation of 2HG, inducing OIS, and mitochondrial dysfunction, triggering MiDAS. Inhibiting these senescence programs or blocking p53 activity reverses the growth defect caused by SLC25A1 dysfunction and restores proliferation. These findings reveal novel pathogenic roles of senescence in human disorders and suggest potential strategies to correct the molecular alterations caused by SLC25A1 loss.

developmental biology↗

bioRxiv2020

Genetic variation at the Cyp6m2 putative insecticide resistance locus in Anopheles gambiae and Anopheles coluzzii

BackgroundThe emergence of insecticide resistance is a major threat to malaria control programmes in Africa, with many different factors contributing to insecticide resistance in its vectors, Anopheles mosquitoes. CYP6M2 has previously been recognized as an important candidate in cytochrome P450-mediated detoxification in Anopheles mosquitoes. As it has been implicated in resistance against pyrethroids, organochlorines and carbamates, its broad metabolic activity makes it a potential agent in insecticide cross-resistance. Currently, allelic variation within the Cyp6m2 gene remains unknown. ResultsHere, we use Illumina whole-genome sequence data from Phase 2 of the Anopheles gambiae 1000 Genomes Project (Ag1000G) to examine genetic variation in the Cyp6m2 gene across 16 populations in 13 countries comprising Anopheles gambiae and Anopheles coluzzii mosquitoes. We find 15 missense biallelic substitutions at high frequency (defined as >5% frequency in one or more populations), that fall into five distinct haplotype groups that carry the main high frequency variants: A13T, D65A, E328Q, Y347F, I359V and A468S. We examine whether these alleles show evidence of selection either through potentially modified enzymatic function or by being linked to variants that change the transcriptional profile of the gene. Despite consistent reports of Cyp6m2 upregulation and metabolic activity in insecticide resistant Anophelines, we find no evidence of directional selection occurring on these variants or on the haplotype clusters in which they are found. ConclusionOur results imply that emerging resistance associated with Cyp6m2 is potentially driven by distant regulatory loci such as transcriptional factors rather than by its missense variants, or that other genes are playing a more significant role in conferring metabolic resistance.

genetics↗

bioRxiv2016

Natural diversity of the malaria vector Anopheles gambiae

The sustainability of malaria control in Africa is threatened by rising levels of insecticide resistance, and new tools to prevent malaria transmission are urgently needed. To gain a better understanding of the mosquito populations that transmit malaria, we sequenced the genomes of 765 wild specimens of Anopheles gambiae and Anopheles coluzzii sampled from 15 locations across Africa. The data reveal high levels of genetic diversity, with over 50 million single nucleotide polymorphisms across the 230 Mbp genome. We observe complex patterns of population structure and marked variations in local population size, some of which may be due at least in part to malaria control interventions. Insecticide resistance genes show strong signatures of recent selection associated with multiple independent mutations spreading over large geographical distances and between species. The genetic variability of natural populations substantially reduces the target space for novel gene-drive strategies for mosquito control. This large dataset provides a foundation for tracking the emergence and spread of insecticide resistance and developing new vector control tools.

genomics↗