INVESTIGADORES
ROCCHETTA Iara
congresos y reuniones científicas
Título:
Oxidative stress response in microalgae and bivalves induced by different environmental conditions
Autor/es:
IARA ROCCHETTA
Lugar:
Delmenshorst
Reunión:
Conferencia; International Conference: Environmental induced oxidative stress in nature and experiment; 2012
Institución organizadora:
Hanse-Wissenschaftskolleg. Institute for Advanced Study
Resumen:
The
objective of this work was to evaluate the effects of aquatic
pollutions (heavy metals and wasted discharges) in different freshwater
organisms for future bioremediation purposes. For that, we studied:
growth curves, morphological changes, carbohydrate, protein and lipid
composition (pigments in algae) and gene expression associated with the
stress condition.The organisms that we have used have been:
Microalgae: two strains of Euglena gracilis (Protist, Euglenoid group)were compared: MAT (isolated from a highly polluted river of Buenos Aires, Matanza River) and UTEX 753 (comercial). Bivalves: Diplodon chilensis (Bivalvia, Hyriidae), a native patagonian freshwater bivalve. Bioassays (EPA protocols (IC50)) were conducted in different culture conditions finding that MAT strain showed to be a tolerant strain (Cr(VI), Cu, Sn, Cd, HCB). We found that in response to a heavy metals, mainly chromium: 1) defense/detoxification system was the same MAT-UTEX, major differences were observed in the GSH + SOD activity being higher in MAT strain, 2) SOD activity was mainly a response of MAT strain and was not in relation to chromium response and 3) MAT (strain isolated from polluted river) showed higher stress response in
relation to the gene expression and metabolic parameters presenting a
more efficient defense system under stress condition. Field studies
were conducted with the bivalves. Population (abundance, frequency,
growth curves, ageing data) and morphometrics parameters, condition
index, morphological changes and antioxidant defense and oxidative
damage (GSH/GSSG, GST, SOD, MDA, carbonyls) were analyzed. Two
populations were compared, one come from an urban polluted place
(mainly fecal bacteria high amount) and the other from a control place
from Lacar lake (Yuco), Neuquen province, Argentina. We found that the
mean size was higher for SMA organisms in compare to the
controls (71 mm vs. 37 mm length) in relation to the higher growth
rate found for the SMA population. On the other hand, the density was lower in SMA bivalves (33 ± 8 indiv./m2 vs. 176±90 indiv./m2). The sewage discharge of SMA city affected: 1)population parameters, as density (<indiv./m2), mean size distribution (> size), higher growth rate and condition index (DGL/SL), 2) stress parameters (GSH, GST, MDA) suggesting a higher metabolism of these organisms, 3)adaptive response to chronic wastewater exposure with oxidative stress not fully compensated (high levels of TBARS, a lipid peroxidation index), 4) This oxidative status was well tolerated by adults as no juvenile recruitment was observed (< 7y) and 5) D. chilensis adult can filter and digest fecal bacteria at high concentrations, making this species a promising tool for bioremediation of urban pollution. Using
two different models as microalgae and bivalves we can conclude that
the environmental factors can affect the oxidative state resulting in
an adaptive response.