Diaz-Terenti, B. | bioRxiv Science

bioRxiv2025

The dynamic transcriptome of Plasmodium malariae in the mosquito

To survive and multiply in different host niches, malaria parasites require sets of proteins that are expressed during the life cycle in a timely manner. Plasmodium malariae is a human malaria parasite that is present in most malaria-endemic regions. However, this species remains enigmatic because it is very challenging to culture, its low parasitaemia in human infections, and frequent co-infection with other malarias. We investigate the transcriptome of P. malariae during transmission in the vector by analyzing RNA-seq data from midgut and salivary gland parasite stages obtained in two experimental mosquito infections with field P. malariae isolates. Our analysis resulted in 3,699 expressed genes, of which 263 are developmentally regulated and 1,338 are P. malariae specific, including genes with unknown functions and without orthologs in other Plasmodium. We detected unique expression patterns of the ApiAP2 family of transcription factors, many of which appear to function as master regulators during sporogony. We found expressed several members of multigene families, like PIR, PHIST, fam-l, and described new families potentially showing transcriptional heterogeneity. Our findings point to the uniqueness of the P. malariae transcriptome, probably related to different transmission traits in the vector, and the lower pathogenicity and virulence in the human.

microbiology↗

bioRxiv2023

Alternative splicing and its regulation in the malaria vector Anopheles gambiae

Alternative splicing (AS) is a highly conserved mechanism that allows to expand the coding capacity of the genome, by modifying how multiple isoforms are expressed or used to generate different phenotypes. Despite its importance in physiology and disease, genome-wide studies of AS are lacking in most insects, including mosquitoes. Even for model organisms, chromatin associated processes involved in the regulation AS are poorly known. In this study, we investigated AS in the mosquito Anopheles gambiae in the context of tissue-specific gene expression and mosquito responses to a Plasmodium falciparum infection, as well as the relationship between patterns of differential isoform expression and usage with chromatin accessibility changes. For this, we combined RNA-seq and ATAC-seq data from A. gambiae midguts and salivary glands, and from infected and non-infected midguts. We report differences between tissues in the expression of 456 isoforms and in the use of 211 isoforms. Secondly, we find a clear and significant association between chromatin accessibility states and tissue-specific patterns of AS. The analysis of differential accessible regions located at splicing sites permitted the identification of several motifs resembling the binding sites of Drosophila transcription factors. Finally, the genome-wide analysis of tissue-dependent enhancer activity revealed that approximately 20% of A. gambiae transcriptional enhancers annotate to a differentially expressed or used isoform and that their activation status is linked to AS differences between tissues. This research illuminates the role of AS in gene expression in vector mosquitoes, and identifies regulatory regions potentially involved in AS regulation, which could reveal novel strategies for vector control.

genomics↗