DISSECTING THE TRANSCRIPTIONAL SWITCH UNDERLYING SEXUAL COMMITMENT IN PLASMODIUM FALCIPARUM & TRANSCRIPTIONAL PROFILING OF DISSOCIATED ADULT CAENORHABDITIS ELEGANS CELLS FROM FOUR MAJOR SOMATIC TISSUES

Abstract

Abstract

Understanding the transcriptional landscape of an organism is paramount to understanding its biology. The transcriptome of an organism, tissue, or cell is to a large degree, what defines its identity. In my thesis I interrogate the transcriptional landscape of two disparate organisms: the single-cell malaria parasite Plasmodium falciparum and the multicellular nematode Caenorhabditis elegans. Despite their wildly disparate biology, transcriptional profiling offers great insights into the mechanisms that define developmental transitions and cell- types in both organisms.

The malaria parasite Plasmodium falciparum is a global health threat that affects hundreds of millions. Transmission of the parasite from its human host into the mosquito vector requires the parasite undergoes a developmental transition from its intraerythrocytic asexual stage to the sexually differentiated gametocyte. Using genome-wide methodologies the apiAP2 transcription factor AP2-G was identified switch controlling this developmental transition. Herein, we demonstrate how AP2-G is essential for parasite sexual differentiation and transmission. This is the first description of a transcriptional switch controlling sexual differentiation in a protozoan parasite, and marks an exciting new target in the fight to eliminate malarial disease worldwide.

Characterizing the unaltered in vivo transcriptome of major tissues is critical to fully understanding the genomic landscape of any multicellular organism. In adult C. elegans the tough outer cuticle has until now prevented the isolation of individual tissues. We developed a technique to lyse adult C. elegans to dissociate the interior cells largely intact. Combining this technique with expression of tissue-specific fluorescent proteins and fluorescence activated cell sorting we can transcriptionally profile individual cell types using next-generation technologies.

We applied our method to four major somatic tissues: neurons, muscle, and hypodermis. These data constitute the first adult C. elegans tissue-specific transcriptome. In comparing our adult data to embryonic and larval transcriptomes, we find the adult transcriptional landscape differs vastly from the profiles of the developing tissues. Finally, we use this method to identified genes that are regulated by the insulin receptor longevity mutant daf-2 specifically in neurons, and are required for its extended short-term memory and axonal regeneration ability. These examples describe the power of cell isolation in adult C. elegans.