Developmental expression pattern of two zebrafish rxfp3 paralogue genes

Area of Science:

• Comparative genomics
• Developmental biology
• Neuroscience

Background:

• The relaxin-3 peptide (RLN3) and its receptor RXFP3 play crucial roles in mammalian physiology.
• Teleost fish possess multiple RXFP3 orthologues, with rxfp3-2a and rxfp3-2b proposed as receptors for Rln3a.

Purpose of the Study:

• To investigate the spatiotemporal expression patterns of zebrafish rxfp3-2b during embryogenesis.
• To compare the expression of RXFP3 in zebrafish with its known patterns in mammals.

Main Methods:

• Reverse transcription-polymerase chain reaction (RT-PCR) to analyze gene transcription.
• Whole-mount in situ hybridization (WISH) to visualize transcript localization in embryos and larvae.

Main Results:

• The rxfp3-2b transcript is ubiquitously present throughout zebrafish embryonic development.
• The rxfp3-2a transcript is only detected at the larval stage.
• rxfp3-2b expression was observed in the brain, retinal ganglion cell layer, and thymus.
• Specific brain regions expressing rxfp3-2b include the optic tectum, thalamus, and habenula.

Conclusions:

• The rxfp3-2b gene shows differential regulation and distinct expression patterns compared to rxfp3-2a during zebrafish development.
• The expression of rxfp3-2b in brain areas associated with visual processing, emotional behaviors, and circadian rhythms suggests conserved functions of the Rln3 system across vertebrates.
• RXFP3 spatiotemporal expression patterns are conserved between zebrafish and mammals.