Faculty Member - Division of Biological Sciences University of Missouri-Columbia

The image shows the distribution of different subtypes of branchiomotor neurons expressing Green Fluorescent Protein (GFP) in zebrafish hindbrain (anterior to the top). The pair of Mauthner reticulospinal neurons in rhombomere 4, and their decussating axons are labeled with the 3A10 antibody (red). The axons exit from the hindbrain and extend into the branchial arches where they innervate jaw and gill muscles

Research description

My laboratory is interested in understanding the cellular and molecular mechanisms underlying the development and physiology of the vertebrate nervous system. Toward this end, we examine the development and function of branchiomotor neurons, which innervate muscles derived from the pharyngeal arches of the embryo, and control jaw and head movements in mammals. We use zebrafish and mouse as our experimental models because these systems offer powerful and complementary approaches to investigate mechanisms underlying development and physiology. Current lab projects include:

1) Understanding the role of the transmembrane protein Strabismus (Stbm) in the tangential migration of branchiomotor neurons in zebrafish. These studies involve structure-function analysis of Stbm using transgenic zebrafish lines, and genetic mosaic analysis in various mutant backgrounds. The data are revealing novel cellular and molecular roles for Stbm in the migration process.

2) Understanding the role of the Stbm/Vangl2, Dishevelled, and other components of the non-canonical Wnt signaling pathway in the tangential migration of branchiomotor neurons in mice. We are using mouse knockouts and conditional alleles to dissect the roles of particular genes in specific cell types. These studies demonstrate broad conservation of mechanisms between fish and mice, and suggest new approaches to address the underlying mechanisms.

3) High-resolution imaging analysis of branchiomotor neuron migration in zebrafish and mouse embryos. We are employing genetic tools to label single motor neurons so as to quantify their migratory behaviors. These studies will provide an essential baseline for future work aimed at testing the roles of specific molecules in neuronal migration.

4) A reverse genetic screen using antisense morpholino nucleotides targeted against the zebrafish secretome to identify new genes involved in branchiomotor neuron development. Promising candidates have been identified among ~40 genes screened thus far, and will be studied further.

We also have ongoing collaborative projects with MU faculty to study hindbrain development, kidney development and physiology, and cardiovascular physiology in zebrafish.

Selected publications

Sittaramane, V., Sawant, A., Wolman, M., Maves, L., Halloran, M. and Chandrasekhar, A. (2009) The cell adhesion molecule Tag1, transmembrane protein Stbm/Vangl2, and Lamininα1 exhibit genetic interactions during migration of facial branchiomotor neurons in zebrafish. Developmental Biology : 325: 363-373.

Sittaramane, V. and Chandrasekhar, A. (2008) Expression of unconventional myosin genes during neuronal development in zebrafish. Gene Expression Patterns: 8: 161-170.

Vanderlaan, G., Tyurina, O., Karlstrom, R. and Chandrasekhar, A. (2005) Gli function is essential for motor neuron induction in zebrafish. Developmental Biology 282: 550-570.

Chandrasekhar, A. (2004) Turning heads: Development of vertebrate branchiomotor neurons. Developmental Dynamics 229: 143-161.