Costas ei al.: Ultraslructural organization in six dinoflagellate species 555 Botanica Marina Vol. 31. pp. 555-562, 1988 A Comparative Morphometrical Study of the Ultrastructural Organization in Six Dinoflagellate Species Using Stereology 1 E. Costas, J. L. Fernandez, M. Navarro* and M. Varela** Seccion de Genetica, Hospital Materno-Infantil Teresa Herrera, Las Jubias. 15006 La Coruna, Spain * Departamento de Production animal, Facultad de Veterinaria, UniversidadComplutense, 28040 Madrid, Spain ** Institute Espaiiol de Oceanogra a, Centra Costero de La Coruna, Apto n° 130, J5080 La Coruna, Spain (Accepted 28 July 1988) Abstract A comparative Ultrastructural study of six dinoflagellate species, Prorocentrum triestinum, Prorocentrum micans, Scrippsiella trochoidea t Gonyaulax excavata, Gonyaulax polyedra and Gymnodinium sp, wich represent the main phylogenetic groups of this phylum, was carried out using stereological procedures. Even though the size of cell and organelles was very variable, the general organization of the cell (proportions of different compartments analyzed) was less variable than the absolute volumes. Thus, the use of relative stereological parameters is preferable because they allow comparison of ultrastructure organization among cells of very different size. Distance coefficients show that the Ultrastructural organization of a species is more related to its phylogeny than it is to its size. Species within a same genus showed small differences while clones of a same species were nearly identical. For all species studied, the number of mitochondria per unit of cell volume remains constant at around 0.09 mitochondria/μιη 3 . Nucleoli showed a high relative variation while the volume of chromosomes related to nucleus volume showed a low degree of variation. It seems that dinoflagellates can occur with very different relative proportions of nucleolus but with a similar number of mitochondria. The species with a higher relative nuclear volume showed a lower growth rate, while species with a higher thylakoid surface showed the higher growth rates. Introduction tmm m i cans Ehrenberg and Prorocentrum triestinum Dinoflagellate ultrastructure has been widely de- Schiller. They also compared morphometrically the scribed at the qualitative level (Dodge 1973, Steidinger nuclear ultrastructure of six dinoflagellate species and Cox 1980). However, morphometrical analyses (Costas and Goyanes 1988). Furthermore, Costas et at the quantitative level on dinophyceae ultrastructure al. (1988), described quantitatively the ultrastructure are scarce. In a pioneer work, Steidinger (1979) de- of P. micans using stereology. scribed the quantitative Ultrastructural variation in Quantitative Ultrastructural studies are more frequent Ptychodiscus brevis Stein. Recently Costas and Goy- in diatoms. Stoermer and Sicko-Goad (1985) carried anes (1987) analysed stereologically the nuclear and out a comparative morphometrical analysis of six chromosome ultrastructure and division of Prorocen- species of the diatom genus Stephanodiscus. Sicko- Goad and Stoermer (1979) and Sicko-Goad (1982) 1 Supported by CA1CYT Grant n° 2409/83 also evaluated morphometrically Ultrastructural Botanica Marina / Vol. 31 / 1988 / Fasc. 6 Copyright © 1988 Walter dc Gruyter · Berlin · New York Brought to you by | University of Queensland - UQ Library Authenticated Download Date | 6/21/15 1:11 AM