Effect of Brefeldin A on the Development of <i>Sargassum cymosum</i> Zygotes (Phaeophyceae, Fucales): Structural and Ultrasctructural Analysis

Abstract

To evaluate the effects of brefeldin A (BFA) on Golgi bodies and indirectly on the polarized development of S . cymosum zygotes, zygotes were cultured at concentrations of 4 μM, 8 μM, 16 μM and 32 μM of BFA, prepared in sterilized seawater. After 12 hours, the samples were fixed and processed for transmission electron microscopy (TEM), confocal laser scanning microscopy, light microscopy and cell counting. For recovery analysis, after treatment, the samples were again place d in sterile seawater for over 12 hours. In the control, after 12 hours, the embryos were adhered and with advanced stage of development, presenting up to 6 cell divisions. In the treated samples, the embryos did not adhere and only in the lower concentrations were they visualized with cellular divisions, is that in the highest concentration , the majority of the zygotes were dead. After recovery, embryos showed development only in the lowest concentrations. By confocal microscopy, the treated samples had an irregular distribution of chloroplasts and physodes. Also through TEM, it was possible to observe the loss of organization of Golgi bodies, in turn leading to the formation of vesicles and fusion of physodes. We can conclude that Golgi bodies are responsible for the production and secretion of molecules related to the adhesion and formation of cell wall membrane , also aiding in the polarization and orientation of physodes. The fused physodes occupied much of the cytoplasm, preventing other cytoplasmic processes, thus directly affecting the development of this alga.