Frankfurt am Main, Germany, May 12, 2014. Hydrogen sulphide (H2S) is a potent inhibitor of aerobic respiration. However populations of shortfin molly fish managed to colonise springs with high concentrations of dissolved hydrogen sulphide. In a new study researchers from LOEWE Biodiversity and Climate Research Centre (BiK-F) and the Goethe University Frankfurt present evidence of genetic changes minimizing the harmful effects of H2S which enable the fish to survive in this deleterious environment. The study provides insight into the molecular mechanisms of this key adaptation for the first time. It is published online today in "Nature Communications".
Shortfin molly fishes (Poecilia mexicana) may only measure a few inches, but they are still exceptional. Populations of Poecilia mexicana, whose relatives are the well-known guppy, colonised sulphide-rich volcanic springs in Southern Mexico. In making this particular habitat their home, they have made the impossible possible, because hydrogen sulphide (H2S), as for many other animal, is lethal. Even at low concentrations the gas blocks the cytochrome c oxidase-complex (COX). The higher the level of hydrogen sulphide, the more the activity of COX is inhibited. As it is essential for respiration, this turns out to be lethal in the end.
Changes in genetic make-up make less susceptible to poison
A team led by Prof. Dr. Markus Pfenninger, LOEWE Biodiversity and Climate Research Centre (BiK-F) and PD Dr. Martin Plath, Goethe University, has taken a closer look at the survivors. Their analysis showed that the COX activity of individuals of shortfin molly fish which colonise H2S-rich waters remains virtually unchanged under high H2S concentrations. This is due to a number of changes in the cox1 and cox3 genes, which have only occurred in populations living in the poisonous springs. Thus, transplanting individuals from non-sulphidic habitat to springs with high H2S levels
|Contact: Dr. Markus Pfenninger|
Goethe University Frankfurt