Life Cycle of <i>Peridinium</i> sp. B3 (Dinophyceae) Isolated from Lake Begnas, Nepal

Abstract

Abstract:Encystment and excystment in the life cycle of a dinoflagellate Peridinium sp. B3, which was isolated from Lake Begnas in the Pokhara Valley, Nepal, were investigated by use of a clonal population.The maximum cell concentration was 3103 vegetative cellsml-1 in BL medium after about 4 weeks at 30C.Sexual reproduction of the cells was induced after the cells in late logarithmic phase were inoculated into nitrogen and phosphorous deficient medium, and also was spontaneously induced in BL medium.Sexual reproduction was isogamous and homothallic. The cycle was initiated by gamete formation, rn which gametes were produced by binary asexual divisions of the vegetative cells. Fusing pairs were formed by the mid-ventral union of gametes. The planozygote retained two red bodies and remained motile for about 2 weeks. Two weeks after the planozygote lost motility, the zygotes enlarged and became dark in color. The theca of the planozygote split around the girdle region and the hypnozygote (cyst) was produced.The matured cysts were dormant and remained viable for at least 1 month at 10C in darkness following maturation for 3 months at 30C. The dark-cold treated cysts excysted synchronously when the incubation temperature was raised to 30C. The protoplast emerged from the cyst wall by amoeboid movement. The excysted cell had two red bodies. This cell divided within 24-48h into 2 daughter cells each with a red body.

Morphology, ultrastructure and molecular phylogeny of Johsia chumphonensis gen. et sp. nov. and Parvodinium parvulum comb. nov. (Peridiniopsidaceae, Dinophyceae)

“…The small cysts are apparently asexual but the large cysts are probably sexual as they are larger than the vegetative cells (19.7 vs 15.6 μm). Small potential gametes were observed as reported previously (Pfiester et al, 1984;Sako et al, 1986) although sexual fusion was not observed. Sexual cysts were generated by Parvodinium inconspicuum in culture (Pfiester et al, 1984), but not detailed in Parvodinium umbonatum (Zhang et al, 2011).Cysts of Johsia chumphonensis differ from those of P. umbonatum and P. inconspicuum in that they are rounded, not pyriform to ovoid (Chu et al, 2008;Tardio et al, 2009).…”

“…The life cycle of Johsia chumphonensis appears complex. Johsia chumphonensis shed the theca through the hypothecal opening and binary division occurs outside the theca, as also reported in an unidentified Parvodinium species (Sako et al, 1986) and Peridinium sanguineum H.J.Carter (Pfiester & Anderson, 1987). It is interesting to note that J. chumphonensis generate two kinds of coccoid cells in cultures differing in the size and wall thickness.…”

Life History of a Marine Dinoflagellate Pyrophacus steinii (Schiller) Wall et Dale

“…Gametes of various dinoflagellate species are distinctive from vegetative cells in their reduced number of chloroplasts per cell and smaller size (Kita et al 1993, Pfiester 1975, 1977, Sako et al 1984, 1986. The male gametes of Pyrophacus steinii are different from the female gametes and the vegetative cells in their smaller size, round shape and fewer thecal plate number.…”

Encystment of Peridinium gatunense: occurrence, favourable environmental conditions and its role in the dinoflagellate life cycle in a subtropical lake

“…Sexual reproduction in dinoflagellates is difficult to recognize because gametes usually look similar to vegetative cells and cell fusion can be confused with division (Pfiester & Anderson, 1987). Nevertheless, sexual cyst formation has been reported for more than 20 dinoflagellate species (Sako et al. , 1986).…”

“…Sexual reproduction in dinoflagellates is difficult to recognize because gametes usually look similar to vegetative cells and cell fusion can be confused with division (Pfiester & Anderson, 1987). Nevertheless, sexual cyst formation has been reported for more than 20 dinoflagellate species (Sako et al, 1986). In this process haploid vegetative dinoflagellate cells produce gametes, pairs of gametes fuse producing a planozygote that loses motility and develops into a hypnozygote cyst.…”