INVESTIGADORES
LIBKIND FRATI Diego
congresos y reuniones científicas
Título:
Synthesis and accumulation of photoprotective compounds (carotenoids and mycosporine-like aminoacids) in heterotrophic aquatic organisms: the role of UV radiation
Autor/es:
PÉREZ, P; LIBKIND FRATI, D; SOMMARUGA, R; DIÉGUEZ, MC; FERRARO, M; ZAGARESE, H; VAN BROOCK, MR
Lugar:
La plata, Arg
Reunión:
Congreso; 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.