Phylogenetic analyses of vector mosquito basic helix-loop-helix transcription factors

Area of Science:

• Genomics
• Molecular Biology
• Evolutionary Biology

Background:

• Basic helix-loop-helix (bHLH) transcription factors regulate diverse developmental processes in organisms.
• Mosquitoes are significant vectors of human diseases, making their biology a critical research area.

Purpose of the Study:

• To identify and characterize bHLH genes in key mosquito species: Aedes aegypti, Anopheles gambiae, and Culex quinquefasciatus.
• To perform phylogenetic analyses and define orthology for mosquito bHLH genes.
• To investigate the evolutionary rates and selection pressures on mosquito bHLH genes.

Main Methods:

• Genome-wide identification of bHLH genes in A. aegypti, A. gambiae, and C. quinquefasciatus.
• Phylogenetic analyses utilizing OrthoDB and KEGG databases to establish gene orthology.
• Comparative analysis of bHLH gene families and evolutionary rates across insect species.

Main Results:

• Identified 55, 55, and 57 bHLH genes in A. aegypti, A. gambiae, and C. quinquefasciatus, respectively.
• Successfully defined orthology for most identified mosquito bHLH genes, updating VectorBase annotations.
• Mosquitoes exhibit expanded bHLH gene families (Atonal, Ngn, Hey) compared to other insects, suggesting enhanced sensory capabilities.
• Mosquito bHLH genes show higher evolutionary rates, with episodic positive selection detected in 11 families.
• Unusually long introns with transposable elements were found in coding regions of some A. aegypti bHLH genes.

Conclusions:

• The expansion and rapid evolution of bHLH genes in mosquitoes likely contribute to their specialized sensory adaptations.
• These findings provide a foundation for future research into bHLH protein functions in mosquito development and disease vector control.