Claude Desplan, PhD

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Silver Professor of Biology
D.Sc./Ph.D., 1983 Université Paris VII
Department of Biology
New York University
LAB WEBSITE:
Claude Desplan Lab

Contact Information
Department of Biology
New York University
1009 Silver Center
100 Washington Square East
New York, N.Y. 10003
Tel.: (212) 998-8218
Fax: (212) 995-4710
E-mail: cd38@nyu.edu

Development and function of the Drosophila visual system

Drosophila visual system development:We study the development and function of the visual system in Drosophila. In flies, color photoreceptors are expressed in stochastic patterns, like the green and red cone cells in the human retina. We have shown that this stochastic choice is made by the transcription factor Spineless when it is turned on in a random subset of R7 photoreceptors and instructs them to express the appropriate Rhodopsin. In a given photoreceptor, each allele of spineless makes its own intrinsic decision to be expressed or not. Then, the two alleles cross-talk through long range communication to specify one fate, or the other (Johnston 2011, 2014).

We have also characterized 80 cell types that compose the optic lobes and are organized around each photoreceptor column. We have identified a temporal cascade of transcription factors that are sequentially expressed in each of the medulla neuroblasts as they age. Together with Notch-dependent binary fate choice, this controls the diversification of the neuronal progeny (Li, 2013). Neuronal specification also depends on a spatial axis: The medulla neuroepithelium is sub-divided into eight subdomains expressing distinct transcription factors that each generates distinct neurons (Erclik 2016; Bertet 2014; Behnia 2014).

Evo-Devo:How much of the regulatory network that specifies the photoreceptor subtypes is retained or has evolved in other animals that use stochastic patterning of their retina? We have shown that butterflies have duplicated the R7 photoreceptor, which allows them to generate three types of stochastically distributed ommatidia that express Spineless in one, two, or zero R7 cells. This allowed for the evolution and deployment of additional opsins, tetrachromacy, and improved color vision. We used CRISPR to knock out spineless in butterflies and showed that there is deep evolutionary conservation of stochastic patterning mechanisms: Our extensive knowledge of the patterning network in the Drosophila visual system allows us to identify how modifications of this network allow adaptation for specific visual requirements.

How can the brain drive distinct caste behaviors in social insects? We use the ant Harpegnathos as a model organism in which individuals can switch caste: Once a queen is removed from a colony, workers transform into pseudo-queens that lay eggs, and, like queens, have a hugely extended lifespan. They also undergo a drastic reduction in optic lobe size.  We are investigating this neurodegenerative process and use CRISPR to generate mutants and transgenes (collaboration with Danny Reinberg, NYU SoM).

Selected Publications: 
  • Rister J, Razzaq A, Boodram P, Desai N, Cleopatra C, Chen H, Jukam D, & Desplan C. Single base pair differences in a shared regulatory element determine differential rhodopsin expression Science, In press (2015)
  • Behnia R., Clark D.A., Carter A.G., Clandinin T.R. & Desplan C. Processing properties of ON and OFF pathways for Drosophila motion detection Nature 512:427-30 (2014)
  • Bertet C., Li X., Erclik T., Cavey M., Wells B. & Desplan C. Temporal patterning of neural progenitors controls Notch-mediated cell survival. Cell 158:1173-86 (2014)
  • Johnston R.J.Jr. & Desplan C.Interchromosomal communication coordinates intrinsically stochastic expression between alleles Science 343:661-5 (2014)
  • Li X, Erclik T, Bertet C, Chen Z, Voutev R, Venkatesh S, Morante J, Celik A, Desplan C. Temporal patterning of Drosophila medulla neuroblasts controls neural fates.Nature 498:456-62 (2013).