Abstracts

Living beings do spontaneously emit (ultra-weak) light in the visible range whose parameters can be related to the metabolic state and/or environment perturbations. By using dedicated photon-counting chambers, the germination of seedlings can be monitored in real time, non-invasive, with applications in agronomy, toxicology and chronobiology to be explored. We will present some ofthe LaFA/FT-UNICAMP results in these area, with brief view of other goals of our group.The sources of biological auto-luminesnce (BAL) in seedlings can be found, as in other organisms, among the by-products of the metabolic activity where reactive chemical species take part, mainly the ones involving radical-oxygen species (ROS) that are electronically excited, and that can occur inside living cells and tissues, such as triplet excited carbonyls and singlet oxygen species, most released during enzymatic reactions. ROS would react with biomolecules and give unstable intermediates as results – such as dioxetanes and tetroxides – that further would form triplet excited carbonyls and/or singlet oxygen, in forms able to further emit photons in the visible range. In effect, BAL occurs for organisms evolving under normal, optimal conditions as well as in response to chronic or acute stressing conditions, physical or chemical.