PI candidate seminar
Third Floor Lecture Hall, Jianzan Building (Phase I)
Chinese Institute for Brain Research, Beijing
10:00-11:00 am, Tuesday，February 4th, 2020
Christophe Dupré, PhD
Department of Molecular and Cellular Biology, Harvard University
Dr. Minmin Luo
Scalability in the nervous system of Hydra
The nervous system can change in size dramatically while keeping its functions intact, which is illustrated by the fact that many species of vastly different sizes exhibit very similar behaviors. In rodents for instance, the brain size can span two orders of magnitude, with the mouse brain having about 70 million neurons whereas the capybara brain has about 1600 million neurons . Uncovering the mechanisms underlying brain scalability can help understand fundamental principles of brain function, since brain size differences among closely related species are frequently observed throughout the evolutionary tree . This problem is difficult to study in rodents because of the complexity of their brain, which makes a side-by-side comparison very challenging. Fortunately, many other animal species can change in size too, some of them placed very early on the evolutionary tree. Among them, the freshwater invertebrate Hydra is an ideal model to pursue such questions since its nervous system is very simple and the same animal can change in size repeatedly by up to an order of magnitude. We aim at reconstructing the nervous system of Hydra using electron microscopy in order to describe how it is built and how it changes when the animal grows and shrinks.
1. Herculano-Houzel, S. (2009). The human brain in numbers: a linearly scaled-up primate brain. Front. Hum. Neurosci. 3, 31.
2. Neves, K., Ferreira, F.M., Tovar-Moll, F., Gravett, N., Bennett, N.C., Kaswera, C., Gilissen, E., Manger, P.R., and Herculano-Houzel, S. (2014). Cellular scaling rules for the brain of afrotherians. Front. Neuroanat. 8, 5.
Christophe Dupré received his undergraduate degree in Neuroengineering from the Swiss Federal Institute of Technology in Lausanne (EPFL). There, he worked in the laboratory of Carmen Sandi on a study linking memory and the expression of neural cell adhesion molecules in the hippocampus. He then went to Rockefeller University to carry his masters’ thesis in the laboratory of Donald Pfaff, where he studied the effects of estrogen hormones on the neurons of the hypothalamus that are modulating mating behavior in mice. This led to a continued stay at Rockefeller in the laboratory of Paul Greengard where as a technician he worked on the regulation of protein phosphorylation in mouse models of psychiatric disorders.
For graduate school, he enrolled in the Neurobiology and Behavior PhD program of Columbia University where he worked under the guidance of professor Rafael Yuste. There, he built custom microscopes and initiated a series of experiments which established Hydra as an animal model for functional imaging of neuronal circuits. To achieve this, he created a transgenic line of Hydra that expresses a calcium indicator in every neuron and built an imaging setup that allows the visualization of every neuron simultaneously in these animals. He found that the nervous system of Hydra is made of several circuits that are completely non-overlapping and which have a strong influence on the display of specific behaviors.
Dr. Dupré is now a postdoctoral fellow at Harvard University in the laboratories of Florian Engert and Jeff Lichtman. Combined with behavioral and neuronal recordings, he is taking advantage of the stunning ability of Hydra to grow and shrink by up to an order of magnitude to investigate how neuronal circuits can change in size while keeping their functions intact. This phenomenon can be observed throughout the evolutionary tree and points at the existence of fundamental mechanisms that allow the use of scalable architectures in the nervous system.