Evolution of hemoglobin function in tropical air‐breathing catfishes

Abstract

The evolution of hemoglobin function in the transition from water‐ to air‐breathing has been highly debated but remains unresolved. Here, we characterized the hemoglobin function in five closely related water‐ and air‐breathing catfishes. We identify distinct directions of hemoglobin evolution in the clades that evolved air‐breathing, and we show strong selection on hemoglobin function within the catfishes. These findings show that the lack of a general direction in hemoglobin function in the transition from water‐ to air‐breathing may have resulted from divergent selection on hemoglobin function in independent clades of air‐breathing fishes.

Structural and oxidative investigation of a recombinant high-yielding fetal hemoglobin mutant

“…Oxygen equilibrium curves were measured for the wt HbF and the HbFα4 mutant using a modified diffusion chamber ( Weber, 1992 ) coupled to a gas mixing system (GMS500, Loligo Systems), as described previously ( Jendroszek et al, 2018 ; Andersen et al, 2021 ). Briefly, pure oxygen (O 2 ) and pure nitrogen gas (N 2 ) were mixed to generate known pO 2 at 37°C.…”