Decoding cis-regulatory elements in the germline of the human malaria vector Anopheles gambiae.

Cis-regulatory elements (CREs) drive tissue- and cell-specific gene expression and are essential for safe, sustainable genetic control strategies in pest and vector insects, including the engineering of gene drives in the primary human-malaria vector Anopheles gambiae. Yet CREs remain poorly defined in mosquitoes due to limited computational tools and practical methods for identification and validation. We present a systematic in silico approach for CRE discovery, correlating targeted DNA-motif searches with gene expression, followed by frequency and distribution analysis within putative promoter regions. Applied to the A. gambiae germline, this approach identified hundreds of putative CREs significantly correlated with germline expression in one or both sexes, often linked to distinct sperm developmental stages and chromosomal locations, suggesting roles in broader regulatory mechanisms such as dosage compensation and meiotic silencing. When mapped onto pre-characterised germline promoters, CRE distribution aligned with regions associated with experimental expression patterns. Finally, we validated a top-ranked testis-enriched CRE using an in vivo dual-reporter assay, showing that mutation of conserved nucleotides drastically altered male germline expression. To the best of our knowledge this work provides the first nucleotide-resolution regulatory genome annotation of the A. gambiae germline, offering a transferable framework to aid promoter design for genetic control strategies against malaria mosquitoes and other insect pests.