A developmental study of serotonin-immunoreactive neurons in the embryonic brain of the marbled crayfish and the migratory locust: evidence for a homologous protocerebral group of neurons.
It is well established that the brains of adult malacostracan crustaceans and winged insects display distinct homologies down to the level of single neuropils such as the central complex and the optic neuropils. We wanted to know if developing insect and crustacean brains also share similarities and therefore have explored how neurotransmitter systems arise during arthropod embryogenesis. Previously, Sintoni et al. (2007) had already reported a homology of an individually identified cluster of neurons in the embryonic crayfish and insect brain, the secondary head spot cells that express the Engrailed protein. In the present study, we have documented the ontogeny of the serotonergic system in embryonic brains of the Marbled Crayfish in comparison to Migratory Locust embryos using immunohistochemical methods combined with confocal laser-scan microscopy. In both species, we found a cluster of early emerging serotonin-immunoreactive neurons in the protocerebrum with neurites that cross to the contralateral brain hemisphere in a characteristic commissure suggesting a homology of this cell cluster. Our study is a first step towards a phylogenetic analysis of neurotransmitter system development and shows that, as for the ventral nerve cord, traits related to neurogenesis in the brain can provide valuable hints for resolving the much debated question of arthropod phylogeny.
Ernst Moritz Arndt Universität Greifswald, Fachbereich Biologie, Zoologisches Institut und Museum, AG Cytology und Evolutionsbiologie, Soldmannstrasse 23, D-17498 Greifswald, Germany. Electronic address: elisabeth.zieger@t-online.de.
Elisabeth
E
Zieger
Unit for "Developmental Biology and Morphology of Animals", Institute for Biology II, RWTH Aachen University, Lukasstr. 1, D-52070 Aachen, Germany.
Peter
P
Bräunig
Ernst Moritz Arndt Universität Greifswald, Fachbereich Biologie, Zoologisches Institut und Museum, AG Cytology und Evolutionsbiologie, Soldmannstrasse 23, D-17498 Greifswald, Germany.
Steffen
S
Harzsch
D025041:Animal Migration; D000818:Animals; D003400:Astacoidea / Q000166:cytology / Q000196:embryology* / Q000254:growth & development; D001921:Brain / Q000166:cytology / Q000196:embryology*; D006110:Grasshoppers / Q000166:cytology / Q000196:embryology* / Q000254:growth & development; D007150:Immunohistochemistry; D009415:Nerve Net / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D018377:Neurotransmitter Agents; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology
D018377:Neurotransmitter Agents; D012701:Serotonin
Brain; Crayfish; Development; Embryo; Immunohistochemistry; Locust; Neurogenesis; Neurophylogeny; Neurotransmitter; Serotonin