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First ultrastructural investigations of the consortium between a phototrophic eukaryotic endocytobiont and Podolampas bipes (Dinophyceae)

2004; Taylor & Francis; Volume: 43; Issue: 5 Linguagem: Inglês

10.2216/i0031-8884-43-5-614.1

2330-2968

Michael Schweikert, Malte Elbrächter,

Marine and coastal ecosystems

Several species of the genus Podolampas (Dinophyceae), P. antarctica, P. bipes, P. elegans, P. palmipes, P. reliculata, P. spinifera and a new undescribed species, were recurrently found in plankton samples of the Atlantic Ocean, Pacific Ocean and the Mediterranean Sea during several oceanographic expeditions. Only P. bipes and P. reticulata always contained autofluorescent endocytobionts, which were interpreted as dinoflagellate chloroplasts by former investigations based on light microscopy. Our investigations of P. bipes showed a consortium of the dinoflagellate and multiple, endocytic cells, each containing chloroplasts, mitochondria, ribosomes, a dictyosome and a eukaryotic nucleus. In culture, these endocytobionts were persistent in the host cells and were distributed into both daughter cells during mitotic cell division. Although endo-symbionts are known from various dinoflagellates, endocytobiosis of several photosynthetic eukaryotic cells per dinoflagellate is new. Ultrastructural details of the endocytobionts show that they belong to the class Dictyochophyceae (Heterokontophyta), most probably to the order Pedinellales. Additionally, further ultrastructural details of P. bipes, such as the presence of three types of extrusomes, intracellular bacteria, rod-like structures composed of tubules and a presumably motile thecal plate, are described.