Real-time photoprotective response of xanthophyll pigments and Mycosporine-like amino acids of Porosira glacialis (Bacillariophyceae)

Abstract

This study is investigation of the newly synthesis of photoprotective compounds by <em>Porosira glacialis</em> in real time using a 13C tracer. Our results showed the relationship between the production rates of mycosporine-like amino acids (MAAs) and photoprotective pigment, such as diadinoxanthin (DD). We were experimented during May 2011 for use in the current experiment on indoor exposure to artificial UV radiation. Our results show that UV tolerance of <em>P. glacialis</em> was evidenced by the growth rate and chlorophyll <em>a</em> (Chl <em>a</em>) concentration under the UV conditions. The carbon uptake rate indicated that was continuously exposed to photosynthetically active radiation (PAR) for 24 hours, which was higher than that of one exposed to ultraviolet (UV) radiation (UVR). However, it indicated when the exposure time was 72 hours, which was higher than the initial value of<em> P. glacialis</em> exposed to UV radiation and also was higher than that of P. glacialis exposed to PAR. The time difference between the productions of these two compounds clearly reveals the defense strategy used by <em>P. glacialis</em> to synthesize photoprotective compounds (MAAs and DD). The results of this study appear to reflect the synthetic pathways of photoprotective compounds and the carbon cycle within the cell in contrasting patterns over time that are defined by the production of photoprotective pigments (DD) and MAAs.