INVESTIGADORES
DIEGUEZ Maria Del Carmen
congresos y reuniones científicas
Título:
Synthesis and accumulation of photoprotective compounds in heterotrophic aquatic organisms: the role of UV radiation.
Autor/es:
PATRICIA PÉREZ; DIEGO LIBKIND; RUBÉN SOMMARUGA; MARÍA C. DIÉGUEZ; MARCELA FERRARO; HORACIO E. ZAGARESE; MARÍA R. VANBROCK
Lugar:
LA PLATA
Reunión:
Encuentro; VIII Encuentro Latinoamericano de Fotoquímica y Fotobiología; 2004
Resumen:
Within aquatic organisms the production of carotenoids and mycosporine
like aminoacids (MAAs) has been attributed to bacteria and algae. These
compounds are produced through the shikimic acid pathway (present in
bacteria, algae and fungi) and act as quenchers and screens having an
important role in photoprotection. Most heterotrophs lack the ability to
synthesize carotenoids and MAAs and thus, present dietary uptake storing the compounds
in their tissues. Fungi are important constituents of aquatic communities and
several species of this group are known to produced carotenoids. However, up to
now, there is no evidence that they would synthesize mycosporine like
aminoacids. In this work we analyze the effect of UV radiation in the
production of carotenoids and mycosporine like aminoacids in aquatic wild
yeasts. Besides, we study the dietary uptake of these compounds in a common
freshwater planktonic copepod under different radiation scenarios. Laboratory
experiments were performed to analyze the synthesis of carotenoids and
MAAs in several aquatic wild yeast strains isolated from Patagonian lakes under
different light treatments (Dark, PAR and PAR+UVR). Besides, the dietary uptake
of mycosporine like aminoacids produced by wild yeasts was studied by
long-term cultures of the copepod Boeckella antiqua under PAR and PAR+UVR
treatments. Carotenoids yields in the yeasts strains tested in our experiments
were highly stimulated by PAR+UVR compared to PAR alone and Dark treatments.
Besides, several strains produced also a UV absorbing compound (309 nm)
exclusively in the PAR and PAR+UVR treatments. This compound was determined as
mycosporine glutaminol glucoside (myc-glu-glu) by means of HPLC and mass
spectrometry analyses. A similar pattern was found when culturing the copepod
B. antiqua fed with the yeast Rhodotorula minuta (MAAs+, induced production of
myc-glu-glu by PAR+UVR). Uptake of the yeasts MAA by this copepod was found
exclusively in the PAR-UVR treatment. Overall, our results show that production
and accumulation of photoprotective compounds are stimulated under UVR stress
and are likely to favor sustained growth under enhanced UV radiation.