Cis-regulatory inactivation of vitamin D signaling confers extreme calcium tolerance in Jialing fish.

Cis-regulatory inactivation of vitamin D signaling enables Jialing fish to tolerate calcium levels three times higher than typical freshwater environments.

• Why it matters: Understanding how vertebrates adapt to extreme environmental conditions can reveal fundamental mechanisms of evolution and resilience, especially in calcium-rich habitats.
• What they did: Researchers compared lake and river populations of Schizopygopsis kialingensis, using transcriptomics and gene editing to identify mutations in vdrb enhancer regions that suppress vitamin D receptor activity.
• The result: Suppression of vitamin D signaling genes increased calcium tolerance, demonstrating that cis-regulatory mutations can drive significant ecological adaptations in vertebrates.