PHYTODEATH · Effect of ultraviolet radiation on programmed cell death in phytoplankton: impact on biomass cycling and biodiversity
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2004-07-01 → 2005-06-30
- EU contribution
- €40,000
- Participants
- 1
- Scheme
- ERG
Lines connect the coordinator with its partners.
Results in brief
Final Activity Report Summary - PHYTODEATH (Effect of ultraviolet radiation on programmed cell death in phytoplankton: impact on biomass cycling and biodiversity)
In this project we: 1. established the ultraviolet-B radiation (UVB) doses which promoted programmed cell death and determined the species sensitivity to UVB by comparison of the different algal responses at the cellular level. 2. examined the effect of UV radiation in deoxyribonucleic acid (DNA) damage in promoting cell death. 3. studied other effects of UV in the oxidative burst and activation of caspases. In short, we demonstrated the ability of UVB on promoting programmed cell death. Global increases in UVB have the potential to alter marine primary production and affect carbon cycles and marine trophic dynamics. Previous estimates of UVB-induced photoinhibition and effects varied greatly, indicating that a common dose-response by marine phytoplankton might not occur from place to place. When UVB radiation was included in the treatments, such as in PAB treatment, induced a decline of the culture associated with a drastic reduction in cell numbers, a rapid loss of photosynthetic efficiency and an increase in the number of dead cells. The same was observed in the diatom thalassiosira pseudonana. A fluorescence-based measure of photosynthetic efficiency, namely Fv/Fm, decreased from 0.69 to 0.58 in the presence of UVB, whereas ultraviolet-A (UVA) caused a minor decrease of Fv/Fm, as observed by Heraud and Beardall, 2000, and Rijstenbil, 2002. This effect was corroborated by the fact of membrane integrity loss revealed by Sytox staining and esterase activity loss revealed by fluorescein diacetate (FDA) staining. Similar results were also described by Buma et al in 1997, when they studied the effect of UVB radiation on growth of marine phytoplankton in relation to DNA damage. These results paralleled the results obtained with TUNEL staining, in which DNA fragmentation under UVB was shown. Cells produced reactive oxygen species (ROS) after one hour under PAB, as it was shown by the green fluorescence of algae in contrast to the red autofluorescence observed under P or PA. Quantitative analysis of confocal images showed a minor increase of active oxygen production associated with supplemental UVA alone and a 100% increase with additional UVB in thalassiosira pseudonana, as mentioned by Rijstenbil, 2002.
Data: CORDIS, © European Union
Project objective
As a result of the Individual Marie Curie category-30 awarded to Or. Segovia, we have demonstrated that a genetic cell death programme pathway exists in phytoplankton, triggered when the cells are subject to different stress, but that in normal condition s is silenced. Considering the alarming ozone depletion that our planet is suffering, we propose to simulate the increase in UVB irradiation and examine its effects in cultures of several phytoplankton species, under laboratory and natural solar conditi ons. We will asses the ability of UVB to cause irreversible damage at the cellular level, affecting programmed cell death. The material aim of study will be cultured and short-term (h) exposed to different doses of UVB and simulating natural solar radiat ion with an ORIEL solar simulator which is one of the most important innovations in the study of photo biology. The ORIEL solar simulator simulates the solar spectrum with great accuracy, both for the upper part of the atmosphere and for the different oz one levels. Induction of cell death by UVB will be studied by means of: a) reduction in the number of cells, formation of pyrimidine dimmers, cellular viability, DNA condensation and fragmentation (hallmarks of the cell death process); b) detection of ca spases (proteases involved in the cell death process); c) study nutrient accessibility of the media under UVB radiation; and d) study of changes in CO2 fixation, c) and d) will help us to discriminate whether the effect of UVB on cell death is directly e xerted on the cell death genes or through stress provoked in the nutrient metabolism. This will be of great importance in the prediction of the ecological impact in terms of changes in the structure and functioning of marine ecosystems and processes in th e future, due to the genuine natural conditions imitated by the ORIEL solar simulator.
Original text from CORDIS.
Participants
- Universidad de Málaga · MálagaCoordinatorSpain
Links
Data: CORDIS, © European Union