Dinoflagellaten – ein Dauerexperiment der Evolution?

Dinoflagellates play important roles in marine food webs, both as primary producers and as heterotrophic consumers. They produce spectacular phenomena like marine bioluminescence and red tides, and are major components of coral reefs. Members of the group can also synthesize some of the most toxic biogenic compounds currently known. Dinoflagellate's nuclei are extremely large and biochemically unique, while mitochondrial genomes are very small. The plastid diversity of dinoflagellates is also unique: only about half of the species in the group are photosynthetic, but the origin of their plastids is often different. As a consequence dinoflagellate plastids have very diverse physiological and biochemical characteristics. Some of the most complex morphological constructs known in unicellular organisms are found in this group. These include ?harpoons“, used to capture prey, and ?eyes“, that contain substructures reminiscent of lenses, corneas and retinas.     

Stromuli. Plastiden‐Brücken im Netzwerk der Zelle

Plastidic bridges in the plant cell network: Stromules Stromules are mobile protrusions emanating from plastids. They might form bridges between plastids and connect them also with other compartments of the plant cell. They could be involved in coordination of plastid activities and in signalling. Stromules have been first observed in the water fern Selaginella more than 100 years ago. Later improved light microscopy enabled the visualization of stromules in higher plant plastids. 15 years ago, since plants accumulating the green fluorescing proteins (GPF) in the stroma became available they have been newly detected and are now studied intensively. Formation of stromules differs among plant tissues, developmental stages and environmental situations. Actin and myosin are required for the formation of stromules.     

Plastiden und Zellkern im Zwiegespräch

Plastids and nucleus talk Plant cells possess plastids having a small genome containing information for biosynthesis of central proteins of the photosynthetic apparatus. Most components of the photosynthetic apparatus are however encoded by the nuclear genome. This constellation requires intensive communication between the two compartments. Plastids produce continuously signals such as reactive oxygen species and tetrapyrrol biosynthesis intermediates informing about their functionality. RNA‐binding proteins might be involved in transduction of information from plastids to the nucleus.