UCSB neuroscience and biology researchers recently published their discoveries regarding the link between the evolution of the human nervous system and the anatomy of nerve-less sponges in the science journal Proceedings of the National Academy of Sciences.

The study, which is entitled “Functionalization of a protosynaptic gene expression network,” examined an earlier sequencing of the genome belonging to a sponge in the Great Barrier Reef of Australia called the Amphimedon queenslandica and the sequencing of the Amphimedon queenslandica in findings that point to shared ability between sponges lacking nerves and beings that do have nervous systems to engage in synapse formation.

Cecilia Conaco, the paper’s first author and UCSB postdoctoral researcher from the UCSB Department of Molecular, Cellular and Developmental Biology and Neuroscience Research Institute, said in a press release that the goal of the research was to seek more information concerning why an animal lacking neurons could have any relation with those that do have nervous systems.

“Specifically, we were hoping to understand why the marine sponge, despite having almost all the genes necessary to build a neuronal syn- apse, does not have any neurons at all,” Conaco said in a press release. “In the bigger scheme of things, we were hoping to gain an under- standing of the various factors that contribute to the evolution of these complex cellular machines.”

Kenneth Kosik, co-director of UCSB’s Neuroscience Research Institute and Harriman Professor of Neuroscience Research in the Department of Molecular, Cellular and Developmental Biology, said a synapse is the minute junction between cells where chemical and electrical impulses are sent, according to a press release. He added that a synapse is similar to a microprocessor since it sends and receives signals as well as changes behaviors with interaction, an attribute called “plasticity,” according to a press release. While the sponge’s RNA appeared to be active in that it was “turning on and off, as if they were doing some- thing,” according to Kosik’s statement in a press release, he said the sponge’s efforts to make a synapse was still not coordinated, unlike the gene expression in other animals.

“It was as if the synapse gene network was not wired together yet,” Kosik said in a press release. “The critical step in the evolution of the nervous system as we know it was not the invention of a gene that created the synapse, but the regulation of the preexisting genes that were somehow coordinated to express simultaneously, a mechanism that took hold in the rest of the animal kingdom.”

In related upcoming research, scientists will inspect the steps leading to synapse formation while also analyzing changes in the nervous system throughout evolution, in order to investigate how similar the human brain’s development is in relation to that of other beings.

—Staff Report