Research Interests

      Our research is aimed at understanding how axons are guided to their targets during development of the nervous system.  Several families of molecules have been identified that can act as axon guidance cues by either attracting or repelling the motile growth cone at the tip of the growing axon.  There is still relatively little known about how axonal growth cones are guided in the complex in vivo environment, where they must integrate multiple cues.  We are investigating the function of guidance molecules in vivo using the zebrafish embryo as a model system.  The zebrafish is a simple vertebrate with rapidly developing, optically transparent embryos ideal for visualizing developing axons.  We use genetic and molecular manipulation of potential guidance cues combined with live imaging of growing axons to determine how guidance cues function in vivo to control the formation of neural connections.

Teaching

Courses:

Zoology 555:  Laboratory in Developmental Biology
Neuroscience 765:  Developmental Neuroscience

Graduate students currently supervised:

Jeremiah Paulus, (jdpaulus@wisc.edu)
Jeremiah is investigating axon guidance defects in mutant embryos lacking laminin, as well as characterizing other mutant lines obtained from our mutagenesis screen.

Namrata Asuri (asuri@wisc.edu)
Namrata is studying axon guidance of sensory neurons.

Erica Andersen (efandersen@wisc.edu)
Erica is studying axon guidance of sensory neurons.

Students supervised who've recently earned graduate degrees:

Marc Wolman, Ph.D.
Jason Berndt, Ph.D. Neuroscience Training Program
Jill Sakai, Ph.D. Neuroscience Training Program

Selected Publications

• Berndt, J.D. and Halloran, M.C.  (2006) Semaphorin3D promotes cell proliferation and neural crest cell development downstream of TCF in the zebrafish hindbrain.  Development 133:3983-3992. 

• Halloran, M.C. and Wolman, M.A.  (2006)  Repulsion or adhesion: receptors make the call.  Current Opinion Cell Biology 18:533-540.

• Sakai, J.A. and Halloran, M.C.  (2006)  Semaphorin3D guides laterality of retinal ganglion cell projections in zebrafish. Development 133:1035-1044.

• Paulus, J.D. and Halloran, M.C.  (2006)  Zebrafish bashful/Laminin-a1 mutants exhibit multiple axon guidance defects.  Dev Dyn 235:213-224.

• Liu, Y. and Halloran, M.C. (2005)  Central and peripheral branches from one neuron are guided differentially by Sema3D and TAG-1. J Neurosci 25:10556-10563. 

• Stevens, C.B. and Halloran, M.C. (2005)  Developmental expression of Sema3G, a novel zebrafish semaphorin. Gene Expr Patterns 5:647-653.  Erratum-name change to Sema3H.

• Wolman, M.A., Liu, Y., Tawarayama, H., Shoji, W., and Halloran, M.C.  (2004) Repulsion and attraction of axons by Sema3D are mediated by different neuropilins in vivo.  J Neurosci 24:8428-8435.

• Liu, Y., Berndt, J.D., Su, F., Tawarayama, H., Shoji, W., Kuwada, J.Y., and Halloran, M.C. (2004).  Semaphorin3D guides retinal axons along the dorsoventral axis of the tectum.  J Neurosci 24:310-318.

• Halloran, M.C. and Berndt, J.D. (2003).  Current progress in neural crest motility and migration and future prospects for the zebrafish model system. Dev Dyn 228:497-513.