IBIMOL   23987
INSTITUTO DE BIOQUIMICA Y MEDICINA MOLECULAR PROFESOR ALBERTO BOVERIS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Efectos del cambio climático en el fitoplancton marino subantártico
Autor/es:
HERNANDO M; MALANGA G; PUNTARULO S; FERREYRA G
Reunión:
Congreso; Reunión Anual Asociación Argentina Tecnología Nuclear; 2011
Resumen:
The study of the effects of ultraviolet radiation (UVR, 280-400 nm) on high latitud microbial communities is a main concern, not only due to spring ozone decline but also due to predicted reductions in the depth of the upper mixed layer resulting from global warming. Such effects could modified significantly the carbon flux between the atmosphere and deep ocean (biological pump). The objetive of the present study was to evaluate the oxidative stress generated on a natural Sub-antarctic phytoplankton community (Beagle Channel 54º 52´S, 68º 18´W) exposed to different ultraviolet B radiation (UVB, 280-315 nm) conditions: normal (NUVB) and increased (HUVB) simulating low ozone, under high temperature condition (normal plus 3°C). In order to evaluated the oxidative stress, reactive species to the tiobarbituric acid (TBARS) was used as index of damage and for cell protection, the concentration of the antioxidant a-tocopherol. In day 1 and 4 a significant increase was observed in the content of TBARS under conditions of HUVB (3.71 and 6.3 nmol.carbono-1 respectively, P< 0.01) compared with NUVB (2.07 and 3.9 nmol.carbono-1 respectively, P< 0.01). In the following days concentrations of TBARS decreased significantly without showing significant differences between treatments. Comparing with initial values, it was observed a significant increase in the content of J-tocopherol during day 1 for HUVB (0.09 and 0.16 nmol carbono-1 respectively, P< 0.05) and day 2 for NUVB (0.04 and 0.22 nmol carbono-1-1 respectively, P< 0.01) compared with NUVB (2.07 and 3.9 nmol.carbono-1 respectively, P< 0.01). In the following days concentrations of TBARS decreased significantly without showing significant differences between treatments. Comparing with initial values, it was observed a significant increase in the content of J-tocopherol during day 1 for HUVB (0.09 and 0.16 nmol carbono-1 respectively, P< 0.05) and day 2 for NUVB (0.04 and 0.22 nmol carbono-1-1 respectively, P< 0.01). In the following days concentrations of TBARS decreased significantly without showing significant differences between treatments. Comparing with initial values, it was observed a significant increase in the content of J-tocopherol during day 1 for HUVB (0.09 and 0.16 nmol carbono-1 respectively, P< 0.05) and day 2 for NUVB (0.04 and 0.22 nmol carbono-1-1 respectively, P< 0.05) and day 2 for NUVB (0.04 and 0.22 nmol carbono-1 respectively, P< 0.05). In the following days these values decreased significantly without showing significant differences between treatments. The taxonomic analysis of the community showed a maximum of diatom biomass in day 3, being significantly high for NUVB. Starting from day 4 a significant decrease was determined in diatom biomass under both experimental conditions and phytoflagellates began to dominate. In days 5 and 7, phytoflagellates biomass was significantly high in HUVB. Overall, our results support the idea that UVR damage/repair balance involves the combined action of several internal factors in the cell. The exposure of phytoplankton to mild oxidative stress initiates, during first day of exposure, a series of adaptive responses that provide increased protection against more severe stress. The structure of phytoplankton community seems to play a central role in this response. Change of the specific composition favored to the small phytoflagellates that showed a low lipid damage under high UVB in high temperature conditions. The low oxidative stress could be attributed to an enzymatic repair of the DNA damage in phytoflagellates.