New method for establishing the cyst-motile form relationship in modern dinoflagellates

• Published in: Fossils Vol. 80; pp. 33 - 40
• Main Authors: Matsuoka, Kazumi, Nogami, Noriko, Kawami, Hisae, Iwataki, Mitsunori
• Format: Journal Article
• Language: Japanese
• Published: Palaeontological Society of Japan 28.09.2006
• Subjects: Alexandrium hiranoi; cyst-motile form relationship; dinoflagellate cyst; molecular phylogenetic analysis; Pyrophacus steinii; single cell PCR
• ISSN: 0022-9202; 2424-2632
• DOI: 10.14825/kaseki.80.0_33

Dinoflagellates are one of major microplankton groups in marine coastal environments. Most dinoflagellates have several different stages in their life cycle consisting of motile and resting periods. Since chemical composition of the cyst is sporopollenin-like and resistant to physical, chemical, and biological decay, these cysts are preserved as fossils and are used as biostratigraphic index markers. Under these circumstances, motile cells of dinoflagellates have been mainly studied by biologists, and resting cysts by paleontologists. Therefore, many species which can produce resting cysts have two different names for different stages. Some of their relationships, however, are still unclear. In this study molecular analytical method for dinoflagellate cysts is applied for elucidating the relationships between cysts and motile cells, and to identify uncertain cysts. Through this study, the following two subjects are conducted; (1) The efficiency of molecular analytical method using a single cyst was examined. Pyrophacus steinii of which motile cells and cysts relationships has been clarified by the cyst (= Tuberculodinium vancampoae) incubation experiment was provided. The small subunit rDNA gene sequences of P. steinii cyst was detected and compared with that of the motile cell provided from the gene database. In the result, the base sequences of this cyst corresponded to that of the motile cell except for one undeterminable base. (2) Aspherical Alexandrium-like cyst without any prominent morphological features was identified by this method. The base sequence of this cyst corresponded to these of Alexandrium hiranoi motile cells provided from the gene database expecting undeterminable 14 bases. These results suggest that molecular analytical method is applicable for identification on modern uncertain dinoflagellates cysts. It could be particularly useful for discrimination of morphologically similar cysts such as toxic Alexandrium species.