Hydrogen sulphide sensitivity and tolerance in genetically distinct lineages of a selfing mangrove fish ( Kryptolebias m
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ORIGINAL ARTICLE
Hydrogen sulphide sensitivity and tolerance in genetically distinct lineages of a selfing mangrove fish (Kryptolebias marmoratus) Keri E. Martin1 · Suzanne Currie2 Received: 28 April 2020 / Revised: 16 July 2020 / Accepted: 4 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Mangroves are critical marine habitats. High hydrogen sulphide (H2S) is a feature of these important ecosystems and its toxicity creates a challenge for mangrove inhabitants. The mangrove rivulus (Kryptolebias marmoratus) is a selfing, hermaphroditic, amphibious fish that can survive exposure to 1116 μM H 2S in the wild. These fish rely on cutaneous respiration for gas and ion exchange when emerged. We hypothesized that the skin surface is fundamentally important in H 2S tolerance in these mangrove fish by limiting H 2S permeability. To test our hypothesis, we first disrupted the skin surface in one isogenic lineage and measured H 2S tolerance and sensitivity. We increased water H 2S concentration until emersion as a measure of the ability to sense and react to H2S, which we refer to as sensitivity. We then determined H2S tolerance by preventing emersion and increasing H 2S until loss of equilibrium (LOE). The H 2S concentration at emersion and LOE were significantly affected by disrupting the skin surface, providing support that the skin is involved in limiting H2S permeability. Capitalizing on their unique reproductive strategy, we used three distinct isogenic lineages to test the hypothesis that there would be genetic differences in H2S sensitivity and tolerance. We found significant differences in emersion concentration only among lineages, suggesting a genetic component to H 2S sensitivity but not tolerance. Our study also demonstrated that external skin modifications and avoidance behaviours are two distinct strategies used to tolerate ecologically relevant H 2S concentrations and likely facilitate survival in challenging mangrove habitats. Keywords Mangrove rivulus · Emersion · Isogenic · Mucous
Introduction Hydrogen sulphide (H2S) is a dangerous aquatic toxin, lethal to most animals at low concentrations (Reiffenstein et al. 1992). H2S reversibly binds to cytochrome c oxidase, hemoglobin and other enzymes (e.g. succinic dehydrogenase, ATPase, glucose-6-phosphate dehydrogenase) inhibiting mitochondrial respiration and oxygen transport (Bagarinao 1992; Cooper and Brown 2008). Hydrogen sulphide is produced endogenously at low levels by enzymatic and non-enzymatic pathways and acts as a gasotransmitter Communicated by Bernd Pelster. * Suzanne Currie [email protected] 1
Department of Biology, Mount Allison University, Sackville, NB, Canada
Department of Biology, Acadia University, Wolfville, NS, Canada
2
influencing several intracellular signaling processes, dilating blood vessels and decreasing blood pressure (Olson 2008; Li et al. 2011). In the environment, H 2S is produced naturally, either geothermally or by bacterial metabolism, and/ or an
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