Detection of changes in mitochondrial hydrogen sulfide i n vivo in the fish model Poecilia mexicana (Poeciliidae)

In this paper, we outline the use of a mitochondria-targeted ratiometric mass spectrometry probe, MitoA, to detect in vivo changes in mitochondrial hydrogen sulfide (H 2 S) in Poecilia mexicana (family Poeciliidae). MitoA is introduced via intraperitoneal injection into the animal and is taken up by mitochondria, where it reacts with H 2 S to form the product MitoN. The MitoN/MitoA ratio can be used to assess relative changes in the amounts of mitochondrial H 2 S produced over time. We describe the use of MitoA in the fish species P. mexicana to illustrate the steps for adopting the use of MitoA in a new organism, including extraction and purification of MitoA and MitoN from tissues followed by tandem mass spectrometry. In this proof-of-concept study we exposed H 2 S tolerant P. mexicana to 59 µM free H 2 S for 5 h, which resulted in increased MitoN/MitoA in brain and gills, but not in liver or muscle, demonstrating increased mitochondrial H 2 S levels in select tissues following whole-animal H 2 S exposure. This is the first time that accumulation of H 2 S has been observed in vivo during whole-animal exposure to free H 2 S using MitoA. This article has an associated First Person interview with the first author of the paper.