DIVISION SYNCHRONY IN PRIMARY CULTURES OF AN ENDOZOIC DINOFLAGELLATE¹

Abstract

SUMMARY Division cysts of zooxanthellae harbored by Anthopleura elegantissima were isolated from random host‐associated populations by their preferential attachment to plastic surfaces. By selecting cysts at similar stages in the cell cycle, synchronous division, excystation, and daughter cell reencystment were obtained in a medium enriched with amino acids. The interval of DNA synthesis in a single growth cycle was determined by pulse‐labeling with radioactive thymidine. Analysis of the sequence of morphologic changes within such cycles suggested that the initial selection procedure isolates G2 cells. The transit time from first generation G2 division cysts to subsequent reentry into G2 was about 70 hr.

Life Cycle of the Heterotrophic Dinoflagellate Pfiesteria Piscicida (Dinophyceae)1

“…(Kita et al 1985), and Paulsonella spp. (Drebes and Schnepf 1988) and is relatively common among other dinoflagellates (Franker 1971, von Stosch 1973, Kita et al 1985, Drebes and Schnepf 1988, Garcés et al 1998, Giacobbe and Yang 1999).…”

Life Cycle of the Heterotrophic Dinoflagellate Pfiesteria Piscicida (Dinophyceae)1

“…(Kita et al 1985), and Paulsonella spp. (Drebes and Schnepf 1988) and is relatively common among other dinoflagellates (Franker 1971, von Stosch 1973, Kita et al 1985, Drebes and Schnepf 1988, Garcés et al 1998, Giacobbe and Yang 1999. The possibility of binary fission in motile dinospores was addressed using a preserved sample from a rapidly dividing P. piscicida population (1 ϫ 10 4 cellsؒmL Ϫ1 ) grown on fish.…”

Cell Cycle and Mitosis

“…Galleron and Durrand noted (p. 162) that Amphidinium carterae does ex hibit "distinct S, G2, and M phases" of the cell cycle. The exact nature of the synthesis is still to be determined; however, Galleron and Durrand have begun to probe this problem using After reviewing the present literature on dinoflagellate cell cycles one can summarize by noting that five studies advocate a discrete period of DNA synthesis corresponding to an S phase in the cell cycle (Franker, 1971;Franker et ai, 1974;Loeblich, 1976;Spector et ai, 1981;Sweeney, 1981), two studies suggest that DNA synthesis is continuous and reminiscent of prokaryotic synthesis (Dodge, 1966;Filfilan and Sigee, 1977), and the re maining report, by Galleron and Durrand (1979), demonstrates that an S phase is present but residual incorporation of label occurs at other stages of the cell cycle as well. Like P. micans (Filfilan and Sigee, 1977), Amphidinium also exhibits a continuous low level of DNA synthesis.…”