Research Our laboratory focuses on two major developmental questions: The evolution of early embryonic development and the establishment of retinal and brain circuitry that underlies color vision. These two distinct systems represent paradigms for understanding how pattern formation is genetically controlled. * The first project is an
Evolution and Development (Evo-Devo) approach to the earliest steps of
insect development, the formation of the antero-posterior embryonic
axis. In flies, the morphogenetic gradient of the Bicoid protein is essential for anterior development. However, bicoid
is not conserved and is a newly evolved gene that has taken over the
ancestral function performed by another more general system in other
insects. We are using the wasp Nasonia as an alternate model system to study how a very distant species patterns its axis. Nasonia is a hymenopteran that diverged from dipterans over
* The other system that we study
is the determination of the retinal mosaic and neural network that
underlie color vision in flies. Color vision is achieved through the
comparison in the brain of inputs coming from photoreceptors containing
photopigments (rhodopsins) with different wavelength specificity.
Different rhodopsins are expressed in stochastic but mutually Teaching "Principles of Biology" (V230012). This is the Freshman course in Biology for undergraduates. "Biocore I and III" (G23.1001 & G23.2003). This is the core course for PhD and MS students, focusing on molecular and cellular processes "Molecular and Cellular Biology". (V23.0022) This is the high level Biology Sophomore class for undergraduate Biology majors. "Molecular Controls of animal form and function" (G23.1072). A graduate course focusing on the evolution of patterning mechanisms. "Developmental Genetics I and II" (G16.2610) with the Skirball Institute, NYU Medical School. This is a high level team-taught course for PhD students in the common Developmental Genetics curriculum. Also teaching Biocore II and IV (G23.1002 & G23.2004) and "Cell Molecular Development Neuroscience" (G80.2201) at the Center for Neuroscience. Biosketch
Areas of Research/Interest Genetic and Mechanistic approaches to development. From the early Drosophila embryo to the eye Fellowships/Honors Ecole Normale Supérieure de Saint Cloud, "Agregation" in Physiology and Biochemistry (Paris); Award from the Fondation Simone et Cino Del Duca; Award from the Fondation pour la Recherche sur le Cancer; Postdoctoral Fellow from the Fogarty International Center and European Molecular Biology Organization; Andre Meyer Fellow, The Rockefeller University; Howard Hughes Medical Institute Associate Investigator, 1988-1999.
Publications
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200MY ago and does not have a bicoid
gene. It exhibits a long germband mode of development that is very
similar to that of flies: All segments form at the same time and the
embryo occupies the entire length of the egg. In contrast, short
germband insects such as Tribolium only generate a few head and
thoracic segments that form in a small posterior part of the egg: all
other segments are added later in a growth zone. This similarity with
flies allows us to directly compare expression patterns with those of
flies. Furthermore, the sequence of the Nasonia genome was
recently completed and there are many early developmental mutants.
Finally, parental RNAi is a very powerful technique to knock down gene
function. We have shown that Nasonia, like flies, utilizes an
anterior morphogenetic center to generate the patterning information
required for the formation of all segments: flies have bcd mRNA
localized at the anterior of the egg while Nasonia has
localized otd mRNA, at both poles. This represents a convergence of two
distinct strategies to create the needed patterning information
required for long germband development. Our ongoing investigations
attempt to understand the entire segmentation pattern in Nasonia, with the goal of reaching the same level of mechanistic detail as Drosophila in order to compare the two systems.
exclusive patterns in the compound eye of Drosophila
as in cones of the vertebrate retina. This implies that there is a
process for choosing a given rhodopsin gene and to transcriptionally
repress all others. From this choice, another mechanism must then
inform the brain of its connection to a photoreceptor with a specific
color sensitivity. We have used molecular and genetic approaches to
identify most of the functions involved in the establishment of the
retinal mosaic and the signaling pathways responsible for the
elaboration of this sensory system. We are also imaging the target
neurons of photoreceptors in the optic lobes and we are manipulating
(ablation or silencing) these neurons to obtain a functional map the
neural network underlying color vision. We have developed a color
behavior assay to assay how changes in the retina or optic lobe neurons
affect the visual process. We hope to understand how color vision has
evolved and how brain processing allows the fly to detect its color
environment.