Nervous system development in sea spiders (Arthropoda, Pycnogonida): combining morphology and gene expression to reconstruct the euarthropod ground pattern
Zusammenfassung der Projektergebnisse
With this project we contribute the first comprehensive account of pycnogonid embryonic and postembryonic nervous system development using modern methods. Our results show that embryonic neurogenesis shows a pattern that, on the one hand, is similar to what has been described for Euchelicerata and Myriapoda. This concerns neurogenesis via groups of mostly postmitotic cells that become internalized from the neuroectoderm. On the other hand, the occurrence of large neural stem cells that divide asymmetrically resemble the neuroblasts formed in crustaceans and hexapods. These data are discussed in the framework of current views of arthropod relationships. However, due to uncertain homologisation and a lack of data, in particular of Myriapoda, the perspective on the evolution of neurogenesis remains ambiguous. The development and the role of the ‘ventral organs’ could be specified. They are important elements of late embryonic, postembryonic, and (very likely) adult neurogenesis. They form a pycnogonid cluster-stream-system comparable to the neurogenic niches in decapod crustaceans. Like the life-long decapod neurogenic system, the pycnogonid ‘ventral organs’ are associated with glomerulus-like neuropils. This suggests a role for the olfactory system. Since similar structures have been reported from onychophoran hypocerebral organs, the putative sister-group of arthropods, we tentatively discuss the evolution of an olfaction related life-long neurogenic system in arthropods. Again, this is hampered by a lack of data and ambiguous homologies.
Projektbezogene Publikationen (Auswahl)
- (2011) Morphogenesis of Pseudopallene sp. (Pycnogonida, Callipallenidae) I: embryonic development. Development, Genes and Evolution 221: 309-28
Brenneis G., Arango C.P., Scholtz G.
- (2011). Morphogenesis of Pseudopallene sp. (Pycnogonida, Callipallenidae) II: postembryonic development. Development, Genes and Evolution 221: 329-50
Brenneis G., Arango C.P., Scholtz G.
- (2013) Embryonic neurogenesis in Pseudopallene sp. (Arthropoda, Pycnogonida) includes two subsequent phases with similarities to different arthropod groups. EvoDevo 4:32
Brenneis G., Stollewerk A., Scholtz G.
(Siehe online unter https://doi.org/10.1186/2041-9139-4-32) - (2013) New species of Australian Pseudopallene (Pycnogonida: Callipallenidae) based on live colouration, morphology and DNA. Zootaxa 3616: 401-436
Arango C.P. & Brenneis G.
- (2013) On the embryonic and post-embryonic development of Pseudopallene sp. (Arthropoda, Pycnogonida) with special focus on neurogenesis and nervous system differentiation. Doctoral thesis, Humboldt- Universität zu Berlin, 183 p.
Brenneis G.
- (2014) The ‘ventral organs’ of Pycnogonida (Arthropoda) are neurogenic niches of late embryonic and post-embryonic nervous system development. PLoS One 9(4):e95435
Brenneis G. & Scholtz G.
(Siehe online unter https://doi.org/10.1371/journal.pone.0095435)
