Brain architecture in the light of evolution

Main area:Marine biology
Target group:Biology
Educational level:Bachelor, Masters
Project description:

Analysing the nervous system in four species of Ophryotrocha (Annelida) with histology and immunohistochemistry


The nervous system is supposedly the most conserved organ system in especially invertebrates, and might therefore unveil vital information about how species are related to each other, and which traits are more conserved than others. However, a recent study could demonstrate variation in the commissures in the brain and ventral nervous system as well as between the distribution patterns of neurotransmitters between three closely related, microscopic annelids. Furthermore, this study also found neurotransmitters not overlapping with each other, suggesting that each neuron is specific for only one neurotransmitter, furthermore confirming the so-far mainly rebutted Dale’s principle, which states each neuron is specific for only one neurotransmitter. This finding suggests that small brains can still be quite complex, and that overall functionality might be retained in complexity-reduced brains by decreasing the size of areas with certain functions rather than increasing the multifunctionality of individual cells. We have four species of the genus Ophryotrocha in our lab at the Marine Biological Section in Copenhagen, which are closely related to each other, represent a secondarily size-reduced genus, and have a similar life style.

The overall objective of this project is to reconstruct the possible ancestral pattern of Ophryotrocha, elaborate on the use of neural elements for reconstructing phylogenetic relationships, and test the Dale’s principle on miniature brains. This will be done by assessing the neuropil and ventral nervous system configuration in these four species by means of histology, immunohistochemistry, and advanced bioimaging (CLSM). Based on the outcome of the study, the results will be published in a journal aiming at a comparative-morphological to neurobiological audience.   

Methods used:Microscopy (light microscopy, confocal laser scanning microscopy), immunohistochemistry, 3D-reconstruction
Keywords:Neuropeptides, Morphology, Nervous system, evodevo
Supervisor(s):  Katrine Worsaae