Construction and Expression Analysis of the bin3xOllas Tool Line

Precise detection of endogenous protein expression is essential for understanding gene function <i>in vivo</i> . We generated a <i>Drosophila</i> knock-in line inserting a 3×Ollas tag at the C-terminus of the endogenous <i>biniou</i> ( <i>bin</i> ) locus, enabling specific visualization of the Bin transcription factor. The <i>bin ^3xOllas</i> allele faithfully recapitulates native expression in the visceral mesoderm and does not disrupt Bin function. Integrating single-cell RNA-sequencing data, we further identified Bin expression in adult reproductive tissues, including ovarian escort cells and testis hub and cyst cells. This allele provides a robust tool for studying Bin function and dynamics.