Photo-oxidative stress
Photosynthesis is a process that converts
light into chemical energy. This process can also be very harmful for
photosynthetic organisms because it can lead to the increased production of
reactive oxygen species (ROS) like superoxide radicals (O2-),
hydrogen peroxide (H2O2) and singlet oxygen (1O2)
in the chloroplast. These ROS can damage cellular components like lipids,
proteins and DNA and lead to cell death. However, plants and algae have evolved
efficient protection mechanisms to prevent the formation of ROS. On the other
hand, ROS can also function as signaling molecules inducing cellular responses
like pathogen defense or stress response. We study the genetic response of the
green alga Chlamydomonas reinhardtii
to one specific ROS, singlet oxygen, whose generation is strongly stimulated
during high light stress but also by herbicide treatment and exposure to photo-chemically
active chemicals (photosensitizers). Particularly, we focus on the cellular
response mechanisms of a specific singlet oxygen-induced gene (GPXH) and try to identify components
involved in signaling from the chloroplast to the nucleus (retrograde
signaling). This helps to better understand the cellular mechanisms underlying
the genetic response, what is important for a future application as biomarker
in ecotoxicology.
Schematic model of singlet oxygen response in Chlamydomonas reihhardtii
Former people involved
- Urs Leisinger,
- Régine Dayer
- Karin Rüfenacht