Conservation of dark CPD photolyase function in blind cavefish

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Genetics

Background:

• DNA repair mechanisms are essential for adapting to environmental stressors.
• Photolyases are conserved enzymes that repair UV-induced DNA damage via photoreactivation.
• The blind cavefish, Phreatichthys andruzzii, offers a unique model for studying adaptation in lightless environments.

Purpose of the Study:

• To investigate the evolutionary adaptation of DNA repair systems in the blind cavefish.
• To explore the function of photolyase genes in an environment devoid of UV radiation.
• To identify novel roles of photolyases beyond UV damage repair.

Main Methods:

• Comparative genomics to identify mutations in photolyase genes of P. andruzzii.
• Functional assays using medaka and mammalian cell lines with manipulated photolyase gene function.
• Analysis of DNA repair capabilities for UV-induced and oxidative DNA damage.

Main Results:

• P. andruzzii exhibits polymorphisms and loss-of-function mutations in 6-4 photolyase (6-4phr) and DASH photolyase (DASHphr) genes.
• The CPD photolyase (CPDphr) gene is highly conserved in P. andruzzii.
• CPD photolyase demonstrates a novel light-independent repair function for cyclobutane pyrimidine dimers (CPDs) and 8-oxoguanine (8-OHdG) under oxidative stress.

Conclusions:

• The blind cavefish has selectively conserved the light-independent function of CPD photolyase.
• This conserved function enables the repair of DNA damage caused by oxidative stress in subterranean habitats.
• Photolyases possess adaptable roles in DNA repair, extending beyond UV photoreactivation.