Biology subjects

Sparkes, P. C.

Publications and source records attributed to Sparkes, P. C..

3 recordsLinked to original sources

bioRxiv2024

Mitochondrial ATP synthesis is essential for efficient gametogenesis in Plasmodium falciparum

Interrupting parasite transmission from humans to mosquitoes is vital for malaria elimination and eradication. Plasmodium male and female gametocytes are the gatekeepers of human to mosquito transmission. Whilst dormant in the human host, their divergent roles during transmission become visually apparent soon after ingestion by the mosquito after rapid transformation into gametes - the males forming eight motile sperm-like cells that each aim to fertilise a single female gamete. Here we report that antibodies raised against PfLDH2 allow accurate identification of male gametocytes. Using this novel tool and functional mitochondrial labelling, we show that the male gametocyte mitochondrion is less active than that of female gametocytes. Rather than being a vestigial organelle discarded during male gametogenesis, we demonstrate that mitochondrial ATP synthesis is essential for male gametocytes to complete gametogenesis and inhibition leads to early arrest. Additionally, using a genetically encoded ratiometric sensor of ATP, we show that gametocytes can maintain cytoplasmic ATP homeostasis in the absence of mitochondrial respiration, indicating the essentiality of the gametocyte mitochondrion for transmission alone. Together, this reveals how gametocytes balance the conflicting energy demands of a dormant and active lifestyle and highlights the mitochondria as a rich source of transmission-blocking targets for future drug development.

microbiology↗

bioRxiv2023

Machine Learning-based Phenotypic Imaging to Characterise the Targetable Biology of Plasmodium falciparum Male Gametocytes for the Development of Transmission-Blocking Antimalarials

Preventing parasite transmission from humans to mosquitoes is recognised to be critical for achieving elimination and eradication of malaria. Consequently developing new antimalarial drugs with transmission-blocking properties is a priority. Large screening campaigns have identified many new transmission-blocking molecules, however little is known about how they target the mosquito-transmissible Plasmodium falciparum stage V gametocytes, or how they affect their underlying cell biology. To respond to this knowledge gap, we have developed a machine learning image analysis pipeline to characterise and compare the cellular phenotypes generated by transmission-blocking molecules during male gametogenesis. Using this approach, we studied 40 molecules, categorising their activity based upon timing of action and visual effects on the organisation of tubulin and DNA within the cell. Our data both proposes new modes of action and corroborates existing modes of action of identified transmission-blocking molecules. Furthermore, the characterised molecules provide a new armoury of tool compounds to probe gametocyte cell biology and the generated imaging dataset provides a new reference for researchers to correlate molecular target or gene deletion to specific cellular phenotype. Our analysis pipeline is not optimised for a specific organism and could be applied to any fluorescence microscopy dataset containing cells delineated by bounding boxes, and so is extendible to any disease model.

microbiology↗

bioRxiv2018

An Atlas of Human and Murine Genetic Influences on Osteoporosis

Osteoporosis is a common debilitating chronic disease diagnosed primarily using bone mineral density (BMD). We undertook a comprehensive assessment of human genetic determinants of bone density in 426,824 individuals, identifying a total of 518 genome-wide significant loci, (301 novel), explaining 20% of the total variance in BMD--as estimated by heel quantitative ultrasound (eBMD). Next, meta-analysis identified 13 bone fracture loci in ~1.2M individuals, which were also associated with BMD. We then identified target genes from cell-specific genomic landscape features, including chromatin conformation and accessible chromatin sites, that were strongly enriched for genes known to influence bone density and strength (maximum odds ratio = 58, P = 10-75). We next performed rapid throughput skeletal phenotyping of 126 knockout mice lacking eBMD Target Genes and showed that these mice had an increased frequency of abnormal skeletal phenotypes compared to 526 unselected lines (P < 0.0001). In-depth analysis of one such Target Gene, DAAM2, showed a disproportionate decrease in bone strength relative to mineralization. This comprehensive human and murine genetic atlas provides empirical evidence testing how to link associated SNPs to causal genes, offers new insights into osteoporosis pathophysiology and highlights opportunities for drug development.

genomics↗