Reconstructing the development and functional architecture of the motor neural circuits of the last common animal ancestor

Where did modern nervous systems come from? Joseph Ryan, Ph.D., Mark Martindale, Ph.D., and James Strother, Ph.D., are leading a project to analyze and understand the nervous systems of ctenophores. Also known as comb jellies, these marine animals were the first animal group to branch off from the rest of animals and therefore are key to understanding the nervous systems of the earliest animals. The team will study the net-like nervous system of the ctenophore known as the sea walnut, which is native to the coastal Atlantic, both in the animal’s early development as neurons first arise and by mapping neural circuits in the adult animal that are important for movement and for interpreting sensory input. A better understanding of the nervous systems of ctenophores will shed light both on the sensory capabilities of the earliest animals as well as provide insights into general principles of animal nervous systems (including humans). The team’s work will also yield public data and resources for the broader scientific community.  

Affiliated Investigators

Joseph F. Ryan, Ph.D.

University of Florida

Joseph Ryan is an Associate Professor in the Department of Biology at the University of Florida, and faculty at UF's Whitney Laboratory for Marine Bioscience. His research group investigates the evolutionary processes that have led to the diversity of life on Earth by integrating genomics and phylogenetics with a wide array of other biological fields including cell and developmental biology, systematics, behavior, ecology, and neuroscience. His work is performed mostly in the context of marine invertebrate animals, with published studies on ctenophores, cnidarians, sponges, placozoans, tunicates, sea cucumbers, sea urchins, brittle stars, sea stars, flatworms, bryozoans, annelids, horseshoe crabs, and more. Research from his group has included the publication of numerous animal genomes (including the first published ctenophore genome), large phylogenomic studies in multiple animal lineages, molecular characterization of novel cell and tissue types, investigations of horizontal gene transfer in animals, reproductive behavioral studies, the evolution of sexual and reproductive traits, and the origin and evolution of the nervous system. Ryan received his Ph.D. in bioinformatics from Boston University. He carried out postdoctoral research at the National Human Genome Research Institute of the National Institutes of Health and at the Sars International Centre for Molecular Biology in Norway. 

Mark Q. Martindale, Ph.D.

University of Florida

Mark Martindale is Director of the University of Florida's Whitney Laboratory for Marine Bioscience and Professor in the Department of Biology. He obtained his Ph.D. in zoology at the University of Texas at Austin (1985). His dissertation focused on the role of embryogenesis on the regenerative properties of a group of marine animals called ctenophores. One of the major findings was that congenital morphological abnormalities arising during development could be "cured" during adulthood if a proper regenerative response was initiated. Martindale went on to perform additional experimental work on ctenophores, including generating the embryonic fate map of Mnemiopsis leidyi using intracellular injection of lineage tracers through the 60-cell stage. Subsequently, Martindale was part of the leadership teams that sequenced the first ctenophore genome and provided the first molecular evidence supporting ctenophores as the earliest diverging extant animals (an ongoing debate in the Tree of Life). In 2009, Martindale was awarded the Alexander Kowalevsky Medal for Comparative Embryology by the St. Petersburg Society of Naturalists. In 2010, Dr. Martindale along with Dr. Max Telford founded EvoDevo, the first open access journal in the field of the evolution of development, and served as its co-editor-in-chief for 10 years. Dr. Martindale has broad training in integrative biology and has published more than 200 peer-reviewed papers on a wide variety of topics in some 15 animal phyla, with an emphasis on embryogenesis and regeneration in marine invertebrates. 

James Strother, Ph.D.

University of Florida

James Strother is an Assistant Professor of biology at the University of Florida Whitney Laboratory for Marine Bioscience. His research examines questions at the interface between neurobiology, physiology, and physics using theoretical approaches, calcium imaging, electrophysiology, and advanced microscopy methods. He began his career at the University of California - Berkeley, where he earned his bachelor’s degree in physics. He went on to receive his Ph.D. from the University of California – Irvine for work on the biomechanics of sensory and respiratory systems in fishes and other aquatic organisms. He then performed post-doctoral research at the Howard Hughes Medical Research Institute’s Janelia Research Campus on the computational architecture of the neural circuits in the visual system of Drosophila. During this time, he pioneered pan-neuronal calcium imaging approaches that provided direct evidence that insects employ independent pathways for light ON and light OFF stimuli, similar to the vertebrate retina. He subsequently established his own research program that applies interdisciplinary approaches to explore the function and organization of nervous systems. Recent projects have employed whole-brain imaging to study the functional architecture of neuromodulatory pathways in the vertebrate CNS using zebrafish larvae, and have examined the sensory physiology of ctenophores to gain insights into the evolution of nervous systems. The Strother Lab also develops novel technologies to advance these research aims, and has introduced new microscopy methods for volumetric imaging and produced open-source software toolkits for data analysis.