Super bugs: can heavy metal adapted springtails withstand higher levels of oxidative stress?

Background

Evolution of tolerance to cadmium has been reported for soil dwelling Orchesella cincta (Collembola) populations occurring at metal-contaminated mining sites. Recently, we showed that these tolerant populations can also withstand high levels of oxidative stress caused by paraquat. This makes sense, since it is known that this metal increases the free Iron concentration possibly by its replacement in various proteins and hence increases the cellular amount of this redox-active metal. Hence, Cd tolerant phenotypes should be able to cope with increased oxidative stress besides stress caused by the metal itself.

This project aims to provide mechanistic insight into this proposed cross-tolerant phenotype in O. cincta. We hypothesize that metal stress response at the transcriptional level will partly overlap with differential gene expression of oxidative stress response cause by paraquat in reference populations. We can ask the question whether a common gene expression network has been target of natural selection leading to the evolution of a more general stress tolerant phenotype in O. cincta living at metal contaminated sites.

Approach

Natural O. cincta populations will be sampled from metal-contaminated sites as well as clean reference sites. These populations will be subjected to microarray analyses upon exposure to the heavy metal Cadmium and the oxidative stress compound Paraquat. Bioinformatic analyses will be applied to identify similar and divergent gene expression networks. Data at the transcriptional level will be supported by physiological assays to assess the level of oxidative stress in tolerant and reference animals.

Supervision and information

Dr. Ir. Dick Roelofs (Room H147, W&N building, Vrije Universiteit)
E-mail:  dick.roelofs@vu.nl
Phone: +31 (0)20 – 59 87078