Evolution of the nervous system in nematodes - a comparative immunohistochemical approach

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Nematodes are a taxon rich in species and, despite some textbook simplifications, morphologically diverse. Their nervous system has been investigated in detail in few model species such as Caenorhabditis elegans and Ascaris species. Sporadic data from a broader taxonomical sampling indicate that the fine structure of the nervous system, in particular the architecture of the brain (the distribution of somata around a ring neuropile) and the presence of orthogonal patterns in the trunk may vary. This is of importance for comparisons with closely related taxa within Cycloneuralia, because the structure of the nervous system is considered to be an important character supporting phylogenetic relationships within this taxon. Knowing the structure of the nervous system in the ancestor of nematodes and cycloneuralians is also important for the discussion of evolutive szenaria among Ecdysozoa. Ideal tools to reconstruct the topology of nervous systems are immunohistochemical methods in combination with confocal laser scanning microscopy. Such methods have been used successfully in diverse other taxa, but very little in nematode species. We suggest to compare a number of nematode species with a set of neuronal markers (FMRFamides, serotonin, three different forms of tubulin) in combination with markers for the musculature (phalloidin) and nuclei (DAPI) to produce a comparable set of data covering a broad taxon sampling among nematodes. For species collection and determination we aim to collaborate with scientists from Germany, Belgium and Spain.