Current Projects / Research

To build a brain, the embryo must produce a spatially organized array of a vast number of neurons, then interconnect them. We use genetic and molecular approaches in mouse and chick embryos to investigate the functions of specific genes in brain development. This research has implications for the molecular therapy of neurological disease and injury, and is funded by the March of Dimes and the National Institutes of Health.

Our current research is focused on longitudinal axon guidance. Neurons send long projections through the embryo to innervate their target cells. This process of axon guidance involves active navigation by growing axons using molecular cues in their environment. Our focus is on longitudinal axons that link brain regions. Very little is known about the molecular cues or cellular strategies used during longitudinal axon growth. We are currently exploring the roles of diffusible proteins that act as long distance signals. Our results indicate that the Slit family of chemorepellents, and their Robo receptors, are critical for axons to grow along precise longitudinal pathways, and we are currently investigating Slit/Robo mechanisms using a range of approaches in the embryo and in cultured axons. We are also investigating how other signals, such as the Netrin chemoattractants, and how novel signals and receptors influence longitudinal axon guidance. The goal of these studies is to lead to an integrated view of the molecular mechanisms of longitudinal axon guidance.

Selected Publications (PubMed search for Mastick GS)

Nural HF, Farmer WT, and Mastick Grant S. The Slit receptor Robo1 is predominantly expressed via the Dutt1 alternative promoter in pioneer neurons in the embryonic mouse brain and spinal cord. Gene Expression Patterns, in press (2007).

Amy L. Altick, Christopher Dravis, Tracey Bowdler, Mark Henkemeyer, and Grant S. Mastick. EphB receptor tyrosine kinases control morphological development of the ventral midbrain. Mechanisms of Development 122: 501-512 (2005).

Gary T. Philips, Carrie N. Stair, Hae Young, Emily Wroblewski, Michael A. Berberoglu, Nadean L. Brown, and Grant S. Mastick. Precocious retinal neurons: Pax6 controls timing of differentiation and determination of cell type. Developmental Biology 279(2):308-21 (2005).

H. Feyza Nural and Grant S. Mastick. Pax6 guides a relay of pioneer longitudinal axons in the embryonic mouse forebrain. J Comparative Neurology 479:399–409 (2004).

Gracie L. Andrews and Grant S. Mastick. R-cadherin is a Pax6-regulated, growth-promoting cue for pioneer axons. Journal of Neuroscience 23: 98739880 (2003).

Gracie L. Andrews, Kyuson Yun, John L.R. Rubenstein, and Grant S. Mastick. Dlx transcription factors regulate differentiation of dopaminergic neurons of the ventral thalamus. Molecular and Cellular Neuroscience 23: 107-120 (2003).

M. Swartz, Johann Eberhart, Grant S. Mastick, and Catherine E. Krull. Sparking new frontiers: using in vivo electroporation for genetic manipulations. Developmental Biology 233: 13-21 (2001).

Grant S. Mastick, Gracie L. Andrews, Nicole M. Davis, and Stephen S. Easter, Jr. “Pax-6 functions in boundary formation and axon guidance in the embryonic mouse forebrain.” Development 124: 1985-1997 (1997).

Grant S. Mastick and Stephen S. Easter, Jr. “Initial organization of neurons and tracts in the embryonic mouse fore- and midbrain.” Developmental Biology 173:79-94. (1996).

Additional Links

Cell and Molecular Biology (CMB) Graduate program http://www.unr.edu/cmbprog/default.htm

Currently in the Mastick lab:

Amy Altick, PhD. Postdoctoral fellow. Guidance of longitudinal axons.

W. Todd Farmer, PhD student, Cell and Molecular Biology program. Guidance of longitudinal axons by the Slit proteins and their Robo receptors.

James Dugan, Biology MS program. Guidance of forebrain pioneer axons.

Matthew Beuhler, Biology MS program. Guidance of ascending longitudinal axons.

Samuel McMahon, Biotechnology BS/MS program. Genotyping of mutant mice by multiplex PCR.

Farnaz Shoja-Taheri, rotating PhD student, CMB program.

Brielle Bjorke, rotating MS student, Biochemistry.

Laura Popko, Biology undergrad.

Andrea Stratton, Biochemistry undergrad.

Recent Graduates:

Deanna Milton, Biotechnology BS/MS Degree, 2003. Currently employed in Biochemistry Dept., UNR.

Gary T. Philips, Biotechnology BS/MS Degree, 2003. Currently Ph.D. candidate, Neurobiology, UC Irvine.

Mika Garrett, Biochemistry B.S. 2002. Currently Ph.D. candidate, Vanderbilt Univ.

Carrie N. Stair, Biology Senior Thesis. Regulation of neurogenesis in the eye. Currently MD student, UNSOM.

Lucy Wong, Biochemistry Senior Thesis. Regulation of neurogenesis in the eye. Currently MD student, UNSOM.

Amy Altick, Biochemistry PhD. Postdoctoral fellow, Biology department and Physiology and Cell Biology department.

Feyza Nural, Biochemistry PhD. Currently applying for postdoctoral positions.