Biology subjects

Evers, F.

Publications and source records attributed to Evers, F..

8 recordsLinked to original sources

bioRxiv2026

Quantifying sporozoite inoculum dynamics with the SpitGrid reveals temporal decay and behavioral determinants of Plasmodium transmission

The number of Plasmodium sporozoites expelled by an infected mosquito during a bite, the inoculum size, is a critical but rarely measured factor in transmission. Its temporal dynamics, individual variation, and behavioral underpinnings remain poorly understood. To address this, we developed the SpitGrid, a modular platform that supports natural probing and feeding on artificial substrates, while enabling behavioral characterization combined with non-lethal, sensitive measurement of inoculum size for individual mosquitoes in high-throughput. Using the SpitGrid, we determined inoculum size of Plasmodium falciparum-infected Anopheles stephensi mosquitoes over time and identified a robust temporal structure. Inoculum size peaked shortly after the extrinsic incubation period, and declined approximately log-linearly post peak. Salivary gland parasite load decreased only moderately and was positively associated with inoculum size during the early phase of sporozoite expelling, yet explained only part of the variation observed in inoculum size. Fine-grained behavioral classification confirmed that probing alone can deliver substantial inocula, and revealed that probing more often increased inoculum size while the duration of probing, or if this led to feeding, had little effect. Application of the SpitGrid to Plasmodium vivax-infected mosquitoes similarly showed a temporally structured expelling profile, with generally smaller inocula and a higher proportion of non-expelling mosquitoes. Our observations reveal that Plasmodium infectivity in mosquitoes is a highly dynamics process, challenging the assumption that per-bite transmission potential remains constant over time. We establish the SpitGrid as a flexible tool to gain a nuanced understanding of the determinants of transmission, refine epidemiological models, and evaluate the efficacy of vector- based interventions under biologically relevant conditions. HighlightsWe develop the SpitGrid, a flexible, accessible, low-cost and animal free platform to measure sporozoite expelling We identify a peak in P. falciparum and P. vivax sporozoite expelling by infected Anopheles stephensi mosquitoes early after completion of the extrinsic incubation period, followed by a gradual decline We confirm a correlation between salivary gland load and inoculum size that weakens over time, indicating that a smaller fraction of the remaining salivary gland load is being expelled by older mosquitoes We confirm that mosquito probing alone can deliver substantial sporozoite inoculum independently of a successful bloodmeal By dissecting the behavioral parameters that determine inoculum size, we observe that the initiation of probing is a major determinant of inoculum size with relatively minor roles for probing time and whether biting results in engorgement Compared to P. falciparum, we observe comparatively smaller inocula, in P. vivax-infected mosquitoes a higher rate of non-expellers and similar albeit more moderate temporal structure with an earlier onset of expelling, illustrating cross-species utility of the SpitGrid

microbiology↗

bioRxiv2025

Expelling of P. falciparum sporozoites by Anopheles stephensi mosquitoes during repeated feeding

It is currently unclear whether repeated mosquito feeding attempts achieve pathogen transmission. We measured Plasmodium falciparum sporozoite expelling in Anopheles stephensi mosquitoes during two interrupted feeding attempts. The number of expelled sporozoites was positively correlated with salivary gland sporozoite load during the first feeding effort ({rho}= 0.36, p= 0.0181) but less so during subsequent feeding ({rho}= 0.06, p= 0.6811). The median number of expelled sporozoites was of similar magnitude during the first and second feeding event, with a strong correlation between them ({rho}= 0.56, p= 0.0002). We conclude that repeated feeding results in repeated sporozoite inoculation at similar intensity.

microbiology↗

bioRxiv2025

Building without the architect: the dispensable role of MICOS in de novo cristae formation in malaria parasites

The malaria parasite mitochondria represent the only tractable, naturally occurring system in which cristae, the characteristic invaginations of the inner mitochondrial membrane, are known to be formed de novo. In traditional model organisms, the central complex involved in cristae organization is the mitochondrial contact site and cristae organizing system (MICOS). However, whether MICOS has an active role in the initial formation of cristae remains unclear. We identified two putative Plasmodium falciparum MICOS components, PfMIC19 and PfMIC60 and show that both genes are dispensable in asexual blood stages, gametocytes, and mosquito stages, albeit with a mild reduction in oocyst numbers. Immunofluorescence microscopy and electron tomography of gametocytes lacking either or both MICOS orthologues showed aberrant mitochondrial morphology and abnormal cristae, with a marked reduction of crista junctions. Thus, by utilizing the unique properties of P. falciparum, we confirmed the involvement of PfMIC19 and PfMIC60 in the organization of crista junctions, while providing evidence that MICOS is not required for the initial formation of cristae.

microbiology↗

bioRxiv2024

Detailing organelle division and segregation in Plasmodium falciparum

The malaria causing parasite, Plasmodium falciparum, replicates through a tightly orchestrated process termed schizogony, where approximately 32 daughter parasites are formed in a single infected red blood cell and thousands of daughter cells in mosquito or liver stages. One-per-cell organelles, such as the mitochondrion and apicoplast, need to be properly divided and segregated to ensure a complete set of organelles per daughter parasites. Although this is highly essential, details about the processes and mechanisms involved remain unknown. We developed a new reporter parasite line that allows visualization of the mitochondrion in blood and mosquito stages. Using high-resolution 3D-imaging, we found that the mitochondrion orients in a cartwheel structure, prior to stepwise, non-geometric division during the last stage of schizogony. Analysis of focused ion beam scanning electron microscopy (FIB-SEM) data confirmed these mitochondrial division stages. Furthermore, these data allowed us to elucidate apicoplast division steps, highlighted its close association with the mitochondrion, and showed putative roles of the centriolar plaques (CPs) in apicoplast segregation. These observations form the foundation for a new detailed mechanistic model of mitochondrial and apicoplast division and segregation during P. falciparum schizogony and pave the way for future studies into the proteins and protein complexes involved in organelle division and segregation.

microbiology↗

bioRxiv2023

Comparative Clustering (CompaCt) of eukaryote complexomes identifies novel interactions and sheds light on protein complex evolution

Complexome profiling allows large-scale, untargeted, and comprehensive characterization of protein complexes in a biological sample using a combined approach of separating intact protein complexes e.g., by native gel electrophoresis, followed by mass spectrometric analysis of the proteins in the resulting fractions. Over the last decade, its application has resulted in a large collection of complexome profiling datasets. While computational methods have been developed for the analysis of individual datasets, methods for large-scale comparative analysis of complexomes from multiple species are lacking. Here, we present Comparative Clustering (CompaCt), that performs fully automated integrative analysis of complexome profiling data from multiple species, enabling systematic characterization and comparison of complexomes. CompaCt implements a novel method for leveraging orthology in comparative analysis to allow systematic identification of conserved as well as taxon-specific elements of the analyzed complexomes. We applied this method to a collection of 53 complexome profiles spanning the major branches of the eukaryotes. We demonstrate the ability of CompaCt to robustly identify the composition of protein complexes, and show that integrated analysis of multiple datasets improves characterization of complexes from specific complexome profiles when compared to separate analysis. We identified novel candidate interactors and complexes in a number of species from previously analyzed datasets, like the emp24, the V-ATPase and mitochondrial ATP synthase complexes. Lastly, we demonstrate the utility of CompaCt for the automated large-scale characterization of the complexome of the mosquito Anopheles stephensi shedding light on the evolution of metazoan protein complexes. CompaCt is available from https://github.com/cmbi/compact-bio. Author summaryProteins carry out essential functions in the majority of processes in life, often by binding with other proteins to form multiprotein complexes. State of the art experimental techniques such as complexome profiling enable large-scale identification of protein complexes in a biological sample. With the increase in use of this method in recent years these experiments have been performed on a variety of species, of which the results are publicly available. Combining the results from these experiments presents a computational challenge, but could identify novel protein complexes and provide insights into their evolution. Here, we introduce CompaCt as a method to integrate complexome profiles from multiple species enabling automatic large-scale characterization of protein complexes. It identifies commonalities as well as the differences between species. By applying CompaCt to a collection of complexome profiles, we identified candidate complexes and interacting proteins in a number of species that were not detected in previous separate analyses of these datasets. In doing so we shed light on the evolutionary origin of several protein complex members, pinpointed the function of biomedically relevant proteins, whose role was previously unknown, and performed the first investigation of the Anopheles stephensi complexome, a mosquito that transmits the malaria parasite.

bioinformatics↗

bioRxiv2023

Comparative 3D ultrastructure of Plasmodium falciparum gametocytes

Despite the enormous significance of malaria parasites for global health, some basic features of their ultrastructure remain obscure. In this study, we apply high-resolution volumetric electron microscopy to examine and compare the ultrastructure of Plasmodium falciparum gametocytes of both genders and in different stages of development as well as the more intensively studied asexual blood stages revisiting previously described phenomena in 3D. In doing so, we challenge the widely accepted notion of a single mitochondrion by demonstrating the presence of multiple mitochondria in gametocytes. We also provide evidence for a gametocyte-specific cytostome variant. Furthermore, we generate, among other organelles, the first 3D reconstructions of endoplasmic reticulum (ER), Golgi apparatus, and extraparasitic structures in gametocytes. Assessing interconnectivity between organelles, we find frequent structural appositions between the nucleus, mitochondria, and apicoplast. We provide evidence that the ER is a promiscuous interactor with numerous organelles and the trilaminar membrane of the gametocyte. Public availability of these volumetric electron microscopy resources of wild-type asexual and sexual blood-stage malaria parasites will facilitate reinterrogation of this global dataset with different research questions and expertise. Taken together, we reconstruct the 3D ultrastructure of P. falciparum gametocytes in high detail and shed light on the unique organellar biology of these deadly parasites.

microbiology↗

bioRxiv2020

CEDAR, an online resource for the reporting and exploration of complexome profiling data

Complexome profiling is an emerging omics approach that systematically interrogates the composition of protein complexes (the complexome) of a sample, by combining biochemical separation of native protein complexes with mass-spectrometry based quantitation proteomics. The resulting fractionation profiles hold comprehensive information on the abundance and composition of the complexome, and have a high potential for reuse by experimental and computational researchers. However, the lack of a central resource that provides access to these data, reported with adequate descriptions and an analysis tool, has limited their reuse. Therefore, we established the ComplexomE profiling DAta Resource (CEDAR, www3.cmbi.umcn.nl/cedar/), an openly accessible database for depositing and exploring mass spectrometry data from complexome profiling studies. Compatibility and reusability of the data is ensured by a standardized data and reporting format containing the "minimum information required for a complexome profiling experiment" (MIACE). The data can be accessed through a user-friendly web interface, as well as programmatically using the REST API portal. Additionally, all complexome profiles available on CEDAR can be inspected directly on the website with the profile viewer tool that allows the detection of correlated profiles and inference of potential complexes. In conclusion, CEDAR is a unique, growing and invaluable resource for the study of protein complex composition and dynamics across biological systems.

bioinformatics↗

bioRxiv2020

Composition and stage dynamics of mitochondrial complexes in Plasmodium falciparum

Our current understanding of mitochondrial functioning is largely restricted to traditional model organisms, which only represent a fraction of eukaryotic diversity. The unusual mitochondrion of malaria parasites is a validated drug target but remains poorly understood. Here, we apply complexome profiling to map the inventory of protein complexes across the pathogenic asexual blood stages and the transmissible gametocyte stages of Plasmodium falciparum. We identify remarkably divergent composition and clade-specific additions of all respiratory chain complexes. Furthermore, we show that respiratory chain complex components and linked metabolic pathways are up to 40-fold more prevalent in gametocytes, while glycolytic enzymes are substantially reduced. Underlining this functional switch, we find that cristae are exclusively present in gametocytes. Leveraging these divergent properties and stage dynamics for drug development presents an attractive opportunity to discover novel classes of antimalarials and increase our repertoire of gametocytocidal drugs.

microbiology↗