Vertebral morphological changes driven by rflna lead to body shape differentiation in carp

Area of Science:

• Evolutionary biology
• Genetics
• Developmental biology

Background:

• Vertebrate body shape evolution often involves changes in vertebral number or fusion patterns.
• Distinct carp subspecies, Hebao red carp (HB) and Yellow River carp (YR), show significant body shape differences despite identical vertebral counts.

Purpose of the Study:

• To investigate the morphological and genetic underpinnings of body shape variation between HB and YR carp.
• To identify genetic loci and molecular mechanisms responsible for the compressed morphology in HB carp.

Main Methods:

• Genome-wide association studies (GWAS) and population genetic analyses on F1 and F2 hybrid carp cohorts.
• Transcriptomic analysis to identify differentially expressed genes in the identified selective sweep regions.
• CRISPR/Cas9-mediated knockout of the candidate gene rfln in zebrafish (Danio rerio) for functional validation.

Main Results:

• A significant locus on chromosome A08 (15.99-16.39 Mb) was strongly correlated with body shape traits.
• Haplotype-dependent expression of rflna within this locus suggests its role in axial skeletal patterning.
• Zebrafish knockout of rfln resulted in vertebral malformations, including shortening, fusion, and altered body shape, confirming its function.

Conclusions:

• The study elucidates the morphological and molecular basis for axial remodeling and body shape variation in HB carp.
• rflna plays a conserved regulatory role in teleost skeletal development, influencing vertebral patterning and morphology.