We are broadly interested in answering fundamental questions about the cell biology of Plasmodium parasites
Our long-term goal is to find new therapeutics to halt parasite replication -- either by finding small molecule inhibitors or new vaccine antigens to block critical parasite processes. We hope to achieve this goal by understanding the functions of novel and essential parasite genes.
To that end, two major research questions we currently focus on are:
1. How do Plasmodium parasites orchestrate cell division?
During a single round of replication in a human red blood cell, Plasmodium falciparum parasites generate 20-32 daughter cells called merozoites. To accomplish this feat, the parasite produces several daughter cell nuclei in multiple asynchronous rounds of division, then, in a single round of cytokinesis, divides the syncytium to produce individual merozoites. We are examining the molecular mediators governing this process to gain a functional understanding of how the parasite drives and regulates this complex process.
2. How does the parasite use the second messenger calcium to regulate its life cycle?
Plasmodium parasites use calcium to control transitions between stages of the life cycle, but the proteins that mediate these critical calcium-dependent steps have not been fully identified. We are examining the proteins responsible for modulating calcium signaling and the downstream effectors that respond to calcium signaling.
The primary techniques we use to answer these questions and more are:
1. Advanced imaging techniques
Plasmodium parasites are weird eukaryotic cells - in miniature. Merozoites contain a full complement of eukaryotic organelles, plus several parasite specific ones, all in a 1.2 x 1.8 um cell. Therefore, examining the cell biology of the parasite is complicated by its size. We use super-resolution fluorescence microscopy and volume electron microscopy to circumvent this challenge to the extent possible, and are growing our repertoire of imaging techniques to discover more about this unique parasite’s cell biology.
2. Genetic manipulation of Plasmodium falciparum parasites
Over half of the genes in the Plasmodium genome have no homology to genes of known function. Therefore, to learn more about these genes we rely heavily on techniques to create transgenic parasite strains. We are focused on creatively using existing tools and optimizing current techniques to improve the throughput of Plasmodium gene modification and increase the types of manipulations we can perform, all to increase our understanding of novel gene function in the parasite. We have successfully applied multiple techniques to inducibly regulate the expression of essential parasite genes.
1. 3D rendering of a schizont captured with Airyscan super-resolution microscopy. Blue = DAPI, Green = PfCINCH, Red = PfMORN1
2. Field's stain of merozoites (purple spots surrounding brown hemazoin crystal) egressing from a red blood cell, a calcium dependent process. Scale bar = 2um
3. 3D rendering of a merozoite generated from FIB-SEM data. Blue = nucleus, Purple = rhoptries, Red = micronemes, Green = apicoplast, Pink = mitochondrion, Black = basal ring, Grey = apical ring
4. Replication curve of parasites with and without inducible knockdown of an essential basal complex protein. [+] ATc = without knockdown, [-]ATc = knockdown.