A life-cycle model has been proposed for Dinophysis, but several transitions between stages of this cycle needed more detailed description. In this study, the steps from mating gamete pairs, cell fusion, nuclear fusion, and the fate of planozygotes were tracked and described from incubations of different sexual-cycle stages of D. acuminata Clap. et J. Lachm., D. cf. ovum F. Schütt, and D. acuta Ehrenb. There were several pathways for depauperating division and formation of small and intermediate cells; observed mating tubes that connect mating gamete pairs were more delicate than the feeding tube described in D. acuminata; nuclear fusion occurs following cell fusion. Planozygotes were able to divide and produce several vegetative cells 2-3 weeks after incubation. New pathways were added to the revised sexual life-cycle model of Dinophysis spp. It is hypothesized that planozygotes are the main diploid sexual stage that may be involved in overwintering and seeding strategies. The importance of planozygote division, without further maturation into a resting cyst, as an adaptive strategy for holoplanktonic organisms is discussed.
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J Phycol
August 2020
Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russia.
Prorocentrum minimum is a potentially toxic marine dinoflagellate that often forms massive blooms in estuarine and coastal sea waters. In this study, the life cycle of P. minimum was investigated and sexual reproduction in culture was described for the first time.
View Article and Find Full Text PDFHarmful Algae
December 2017
Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia. Electronic address:
In 2015, a remarkably high density bloom of Alexandrium minutum occurred in Sungai Geting, a semi-enclosed lagoon situated in the northeast of Peninsular Malaysia, causing severe discoloration and contaminated the benthic clams (Polymesoda). Plankton and water samples were collected to investigate the mechanisms of bloom development of this toxic species. Analysis of bloom samples using flow cytometry indicated that the bloom was initiated by the process of active excystment, as planomycetes (>4C cells) were observed in the early stage of the bloom.
View Article and Find Full Text PDFHarmful Algae
September 2017
Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Vigo, Subida a Radio Faro 50, 36390, Vigo, Spain. Electronic address:
Asexual and sexual life cycle events were studied in cultures of the toxic marine dinoflagellate Protoceratium reticulatum. Asexual division by desmoschisis was characterized morphologically and changes in DNA content were analyzed by flow cytometry. The results indicated that haploid cells with a C DNA content occurred only during the light period whereas a shift from a C to a 2C DNA content (indicative of S phase) took place only during darkness.
View Article and Find Full Text PDFPLoS One
June 2016
Universidad de Alcalá (UAH), Dpto de Biomedicina y Biotecnologia, 28801 Alcalá de Henares, Spain.
Dinoflagellates are haploid eukaryotic microalgae in which rapid proliferation causes dense blooms, with harmful health and economic effects to humans. The proliferation mode is mainly asexual, as the sexual cycle is believed to be rare and restricted to stressful environmental conditions. However, sexuality is key to explaining the recurrence of many dinoflagellate blooms because in many species the fate of the planktonic zygotes (planozygotes) is the formation of resistant cysts in the seabed (encystment).
View Article and Find Full Text PDFDeep Sea Res 2 Top Stud Oceanogr
May 2014
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543.
Measurements of the DNA content of different protist populations can shed light on a variety of processes, including cell division, sex, prey ingestion, and parasite invasion. Here, we modified an Imaging FlowCytobot (IFCB), a custom-built flow cytometer that records images of microplankton, to measure the DNA content of large dinoflagellates and other high-DNA content species. The IFCB was also configured to measure fluorescence from Cy3-labeled rRNA probes, aiding the identification of (syn.
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