The alternative oxidase (AOX) increases sulphide tolerance in the highly invasive marine invertebrate Ciona intestinalis

Ecological communities and biodiversity are shaped by both abiotic and biotic factors. This is well illustrated by extreme environments and invasive species. With global change, hydrogen sulphide is an increasing threat for many multicellular organisms. As the formation, size, and abundance of hydrogen sulphide-rich marine environments increase, many species are challenged with the inhibiting effect of sulphide on the aerobic energy production via cytochrome c oxidase, ultimately causing the death of the organism. Interestingly, many protist, yeast, plant, and also animal species possess a sulphide-resistant alternative oxidase (AOX). In this study, we investigated whether AOX is functionally involved in sulphide stress response of the highly invasive marine tunicate, Ciona intestinalis. At the LC50, the sulphide effect on developmental success of AOX knock-down Ciona embryos was three times stronger than on control groups. Further, AOX mRNA levels were higher under sulphide than contro...