SEXUAL REPRODUCTION AND MEIOSIS IN PERIDINIUM INCONSPICUUM LEMMERMANN (DINOPHYCEAE) |
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Authors: | Lois A Pfiester P Timpano J J Skvarla J R Holt |
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Institution: | Department of Botany-Microbiology, University of Oklahoma, Norman, Oklahoma, 73019 |
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Abstract: | In Peridinium inconspicuum Lemmermann, sexual reproduction occurs in both nitrogen-enriched and nitrogen-deficient media. In this homothallic strain, protoplasmic fusion begins between two thecate gametes; but zygote formation is completed in a space outside the fusing pair. This diploid cell can form a plated theca which is shed as the cell enlarges. This spherical zygote then forms a new non-plated theca. The process of ecdysis and the formation of a new non-plated theca is repeated several times. During this process the zygote gradually elongates and by cytoplasmic infurrowing becomes peanut-shaped. Eventually two cells are formed. The first and second meiotic divisions are greatly separated in time. The first meiotic division occurs in the spherical non-thecate zygote. The second meiotic division can occur in the peanut-shaped zygote before it completes cytokinesis. This meiotic division may not be synchronous, occasionally resulting in a trinucleate stage. Eventually four flagellated, haploid products are produced. |
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