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Insights from Sponge Transcriptomes & Physiology about the Early Evolution of Nervous Systems Open Access


Other title
Nervous system
Type of item
Degree grantor
University of Alberta
Author or creator
Farrar, Nathan
Supervisor and department
Dr. Sally Leys
Examining committee member and department
Dr. Warren Gallin (Biological sciences)
Department of Biological Sciences
Physiology, Cell, and Developmental Biology
Date accepted
Graduation date
Master of Science
Degree level
The origin of neurons and neural systems is a research area that has begun to experience increased progress with the growing availability of genomic data from a range of basal metazoans and closely related outgroups. This has allowed a reevaluation of previous models of neural evolution. Consequently, the aim of this thesis was to use new genetic and physiological tools to determine what sponges can tell us about the early evolution of nerves. This thesis reports the finding of near-­‐complete sets of post-­‐synaptic density genes across the sponge classes, as well as selected enzymes involved in the synthesis of classical neurotransmitters. Building on the identification of GABAB receptors I attempted to produce an antibody against the GABAB receptor from the demosponge Spongilla lacustris. However, the polyclonal antibody generated was unable to identify the receptor through Western Blot analysis. Lastly, further elucidation the physiological mechanism behind the demosponge inflation and contraction behavior by demonstrating the presence of a Ca2+ wave acting as a coordination signal was attempted. The results I obtained are consistent, though not definitive, with the spread of a calcium wave as a factor in coordinating this response. Collectively I interpret the results to mean that while sponges have molecules and use processes which are important building blocks of conventional nervous systems, sponges ought not to be perceived as animals with a ‘near nervous system.’ Rather, their genetic components and physiological processes are adaptations to the specific environmental circumstances in which they function.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Riesgo, A., Farrar, N., Windsor, P.J., Giribet, G., Leys, S.P. (2014). The analysis of eight transcriptomes from all Porifera classes reveals surprising genetic complexity in sponges. Mol Biol Evol. 31: 1102-­‐1120.

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