Construction and Expression Analysis of the bin 3xOllas Tool Line.

Precise detection of endogenous protein expression is essential for understanding gene function in vivo . We generated a Drosophila knock-in line inserting a 3×Ollas tag at the C-terminus of the endogenous biniou ( bin ) locus, enabling specific visualization of the Bin transcription factor. The bin 3xOllas 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.