Differential expression of duplicated VAL-opsin genes in the developing zebrafish

Area of Science:

• * Molecular biology
• * Genetics
• * Neuroscience

Background:

• * Non-visual opsins are crucial for various light-dependent physiological processes.
• * VAL-opsinA was previously identified in zebrafish brain and retinal cells.
• * The evolutionary history and function of opsin gene families are actively researched.

Purpose of the Study:

• * To identify and characterize a duplicated VAL-opsin gene (VAL-opsinB) in zebrafish.
• * To investigate the phylogenetic relationship of VAL-opsinB.
• * To determine the spectral sensitivity and expression pattern of VAL-opsinB.

Main Methods:

• * Molecular phylogenetic analysis to determine gene orthology and evolutionary history.
• * Reconstitution of the recombinant VAL-opsinB protein with 11-cis-retinal.
• * In situ expression analysis to map VAL-opsinB localization in zebrafish tissues.

Main Results:

• * VAL-opsinB is identified as a duplicated gene of VAL-opsinA in zebrafish.
• * Phylogenetic analysis confirms VAL-opsinB as orthologous to a salmon gene, with duplication in the teleost lineage.
• * Recombinant VAL-opsinB forms a green-sensitive photopigment and shows a distinct expression pattern in the brain and eye compared to VAL-opsinA.

Conclusions:

• * VAL-opsinB represents a newly characterized non-visual opsin in zebrafish.
• * The duplication and distinct expression of VAL-opsinA and VAL-opsinB suggest specialized, divergent physiological roles.
• * This finding contributes to understanding the diversity and functional evolution of opsin genes in teleosts.