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

• Author / Creator

  Farrar, Nathan

• 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.

• Subjects / Keywords

  • Evolution
  • Porifera
  • Nervous system

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3183485Q

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.