Ultrastructure of motile cells of the green alga Haematococcus pluvialis including the tridimentional reconstruction of the flagellar apparatus

DAMIANI CECILIA,; LEONARDI PATRICIA,; CACERES EDUARDO

Rosario

Congreso; 10 Inter-American Congress of Electron Microscopy 2009; 2009

Interamerican Committee of Societies for Electron Microscopy

Haematococcus pluvialis is a green alga industrially cultivated to obtain the carotenoid pigment astaxanthin. Transmission and scanning electron microscopes were used to elucidate the ultrastructure of motile cells. The atypical cell wall shows two strata, the outer one fibrillar and the inner one formed by adjacent vesicles rectangular in section. The endomembrane system is involved in the wall formation. The central nucleus is surrounded by numerous dictyosomes. A parietal, lobed chloroplast contains several pyrenoids and one eyespot formed by one layer of lipid globules. Cytoplasmatic astaxanhin appears in association with endoplasmic reticulum profiles. Four contractile vacuoles lie adjacent to the plasma membrane. Yellow-gold fluorescence neutral lipid droplets were detected using Nile red with a confocal microscope. Two flagella emerge from an apical papilla. A large mitochondrium is related to the flagellar apparatus. The tridimentional reconstruction of the flagellar apparatus was obtained by means of serial sections. Viewed from the anterior of the cell, it shows 180º rotational symmetry with a clockwise absolute orientation of its components. The cruciate microtubular root system has a 2:4/1:2:4/1 alternation pattern. A striated distal fiber connects both basal bodies. Electron-dense material covers the proximal end of each basal body.is a green alga industrially cultivated to obtain the carotenoid pigment astaxanthin. Transmission and scanning electron microscopes were used to elucidate the ultrastructure of motile cells. The atypical cell wall shows two strata, the outer one fibrillar and the inner one formed by adjacent vesicles rectangular in section. The endomembrane system is involved in the wall formation. The central nucleus is surrounded by numerous dictyosomes. A parietal, lobed chloroplast contains several pyrenoids and one eyespot formed by one layer of lipid globules. Cytoplasmatic astaxanhin appears in association with endoplasmic reticulum profiles. Four contractile vacuoles lie adjacent to the plasma membrane. Yellow-gold fluorescence neutral lipid droplets were detected using Nile red with a confocal microscope. Two flagella emerge from an apical papilla. A large mitochondrium is related to the flagellar apparatus. The tridimentional reconstruction of the flagellar apparatus was obtained by means of serial sections. Viewed from the anterior of the cell, it shows 180º rotational symmetry with a clockwise absolute orientation of its components. The cruciate microtubular root system has a 2:4/1:2:4/1 alternation pattern. A striated distal fiber connects both basal bodies. Electron-dense material covers the proximal end of each basal body.