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.