A novel zinc finger transcription factor resembles krox-20 in structure and in expression pattern in zebrafish

Krx-20, a zinc finger protein, plays an essential role in hindbrain segmentation of vertebrates. Zebrafish gene frb35 encodes a novel zinc finger protein that shares a high homology with Krx-20. The expression domains of frb35 overlap those of krx-20. The expression of frb35 first occurs in the 3rd rhombomere primordium at the onset of segmentation, which is soon followed by expression in the 5th rhombomere. From mid-segmentation onward, the 5th rhombomere has a higher frb35 expression level than the 3rd rhombomere. Unlike krx20, frb35 expression persists in the 5th rhombomere until the end of pharyngula period.