Bondarenko, S. | Search bioRxiv

bioRxiv2023

Mosquito midgut stem cell cellular defense response limits Plasmodium parasite infection

A novel cellular response of midgut progenitors (stem cells and enteroblasts) to Plasmodium berghei infection was investigated in Anopheles stephensi. The presence of developing oocysts triggers proliferation of midgut progenitors that is modulated by the Jak/STAT pathway, and proportional to the number of oocysts on individual midguts. The percentage of parasites in direct contact with enteroblasts increases over time, as progenitors proliferate. Enhancing proliferation of progenitors significantly decreases oocyst numbers, while limiting proliferation increases oocyst survival. Live imaging revealed that enteroblasts interact directly with oocysts and eliminate them. Midgut progenitors sense the presence of Plasmodium oocysts and mount a cellular defense response that involves extensive proliferation and tissue remodeling, followed by oocysts lysis and phagocytosis of parasite remnants by enteroblasts. One-Sentence SummaryMosquito midgut stem cells detect Plasmodium parasites, proliferate and enteroblasts actively eliminate oocysts.

immunology↗

bioRxiv2022

Phylogenomics revealed migration routes and adaptive radiation timing of Holarctic malaria vectors of the Maculipennis group

BackgroundUnderstanding the evolutionary relationships between closely related taxa is important for mosquitoes that transmit human diseases. Six out of 41 dominant malaria vectors in the world belong to the Maculipennis group, which is subdivided into two North American subgroups (Freeborni and Quadrimaculatus), and one Eurasian (Maculipennis) subgroup. Although previous studies considered the Nearctic subgroups as ancestral, details about their relationship with the Palearctic subgroup, and their migration times and routes from North America to Eurasia remain controversial. The Eurasian species An. beklemishevi is currently included in the North American Quadrimaculatus subgroup adding to the uncertainties in mosquito systematics. ResultsTo reconstruct historic relationships between the North American and Eurasian mosquitoes, we conducted a phylogenomic analysis of 11 Palearctic and 2 Nearctic species based on 1271 orthologous genes using their transcriptomic or genomic sequences. The analysis indicated that the Palearctic species An. beklemishevi clusters together with other Eurasian species and represents a basal lineage among them. Also, An. beklemishevi is related more closely to An. freeborni, which inhabits the Western United States, rather than to An. quadrimaculatus, a species from the Eastern United States. The time-calibrated tree suggests a migration of mosquitoes in the Maculipennis group from North America to Eurasia about 20-25 million years ago through the Bering Land Bridge. A Hybridcheck analysis demonstrated highly significant signatures of introgression events between allopatric species An. labranchiae and An. beklemishevi. The analysis also identified ancestral introgression events between An. sacharovi and its Nearctic relative An. freeborni despite their current geographic isolation. ConclusionsOur phylogenomic analyses reveal migration routes and adaptive radiation timing of Holarctic malaria vectors and strongly support inclusion of An. beklemishevi into the Maculipennis subgroup. The vectorial capacity and the ability to diapause during winter evolved multiple times in Maculipennis evolution. Detailed knowledge of the evolutionary history in the Maculipennis subgroup will help us better understand the current and future patterns of malaria transmission in Eurasia.

evolutionary biology↗