Ultrastructure and large subunit rDNA sequences of Lepidodinium viride reveal a close relationship to Lepidodinium chlorophorum comb. nov. (=Gymnodinium chlorophorum)

Abstract

Ultrastructure and large subunit rDNA sequences of Lepidodinium viride reveal a close relationship to Lepidodinium chlorophorum comb. nov. (= Gymnodinium chlorophorum) SUMMARY The ultrastructure of the green dinoflagellate Lepididodinium viride M. M. Watanabe, S. Suda, I. Inouye Sawaguchi et Chihara was studied in detail. The nuclear envelope possessed numerous chambers each furnished with a nuclear pore, a similar arrangement to that found in other gymnodinioids. The flagellar apparatus was essentially identical to Gymnodinium chlorophorum Elbrächter et Schnepf, a species also containing chloroplasts of chlorophyte origin. Of particular interest was the connection of the flagellar apparatus to the nuclear envelope by means of both a fiber and a microtubular extension of the R3 flagellar root. This feature has not been found in other dinoflagellates and suggests a close relationship between these two species. This was confirmed by phylogenetic analysis based on partial sequences of the large subunit (LSU) rDNA gene of L. viride, G. chlorophorum and 16 other unarmoured dinoflagellates, including both the 'type' culture and a new Tasmanian isolate of G. chlorophorum. These two isolates had identical sequences and differed from L. viride by only 3.75% of their partial LSU sequences, considerably less than the difference between other Gymnodinium species. Therefore, based on ultrastructure, pigments and partial LSU rDNA sequences, the genus Lepidodinium was emended to encompass L. chlorophorum comb. nov.

Phylogenetic relations of the dinoflagellate Gymnodinium baicalense from Lake Baikal

“…The latter species is known to be phylogenetically close to the Gymnodinium genus [20]. The phylogenetic analysis of the COI amino acid sequences showed the same tree topology.…”

“…Daugbjerg et al [22] reduced the genus Gymnodinium to include only the following species: the freshwater G. fuscum and G. palustre, the marine G. aureolum, G. catenatum, G. impudicum, G. nolleri, G. cf. placidum and G. chlorophorum (because of a few morphological features the latter is now known as Lepidodinium chlorophorum [20]). Nevertheless, a large number of species are still informally known as members of the Gymnodinium genus.…”

On the origin of chloroplasts, import mechanisms of chloroplast-targeted proteins, and loss of photosynthetic ability — review

“…The analysis of Karenia brevis chloroplast-targeted genes revealed a highly chimeric chloroplast proteome containing enzymes with red algal affinities gained from haptophyte or red algal endosymbionts, enzymes of secondary and tertiary host origin, and some enzymes with green algal affinities gained probably via horizontal gene transfer from green prey engulfed via phagocytosis (Nosenko et al 2006). The dinoflagellates Lepidodinium viride and L. chlorophorum (previously Gymnodinium chlorophorum; see Hansen et al 2007) even possess chloroplasts derived from green algae (Elbrächter and Schnepf 1996;Takishita et al 2008). Furthermore, the dinoflagellate Kryptoperidinium foliaceum possesses a tertiary algal endosymbiont that has retained not only the nucleus and four-membrane-bounded plastids but also mitochondria with genome, and the phylogenies of endosymbiont mitochondrial genes support the diatom (heterokont) origin of this tertiary endosymbiont (Imanian et al 2007).…”

Pigment-based chloroplast types in dinoflagellates

“…The genus Lepidodinium was recently revised (Hansen et al 2007), and the previously named Gymnodinium chlorophorum was renamed as L. chlorophorum. The extant plastid in the dinoflagellate L. viride is most probably acquired by plastid replacement via tertiary endosymbiosis (reviewed by Delwiche 2007).…”