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| Bruce Riley received a B.A. in Biology from the University of Colorado (1982) and a Ph.D. in Molecular Biology from the University of Wisconsin (1990). He held two different post-doctoral positions, one at the University of Wisconsin and the second at the University of Utah. He joined the Department of Biology at Texas A&M University in 1995 and was promoted to Associate Professor in 2001. |
Bruce Riley 3258 TAMU Office: Lab: Fax: 979-845-2891 |
| Developmental Genetics of Zebrafish
The overall goal of research in my laboratory is to elucidate conserved mechanisms of vertebrate embryogenesis through mutational analysis of the zebrafish, Danio rerio. Zebrafish has recently emerged as one of the top model systems for genetically analyzing vertebrate development. Genetics techniques are highly efficient and zebrafish embryos are transparent. This makes it easy to directly observe the effects of altering specific gene functions.
Inner ear development. We are studying the century-old problem of how the otic placode, the precursor of the inner ear, is induced from uncommitted ectoderm. Our recent work shows that Fgf signals secreted from surrounding tissues are necessary and sufficient for induction of the otic placode (Fig 1). After the placode forms, Fgf and Wnt signals from adjacent hindbrain tissue regulate regional identities within the otic placode, including induction of sensory hair cells. How cells in the placode respond to Fgf signals is of particular interest. Members of the Pax2/5/8 family of transcription factors appear to be important mediators of Fgf signaling. Related topics of interest are:
We hypothesize that the resulting Wnt signaling centers help establish the reiterated patterns of cell types found in all rhombomeres. Disruption of either Wnt or Dl-N signaling results in loss of cell types normally associated with rhombomere boundaries, and cell types normally found in rhombomere centers are poorly organized. |
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Millimaki, B. B., Sweet, E. M., Dhason, M. S. and Riley, B. B. (2007). Zebrafish atoh1 genes: Classic proneural activity in the inner ear and regulation by Fgf and Notch. Development 134, 295-305. Kwak, S. J., Vemaraju, S., Moorman, S. J., Zeddies, D., Popper, A. N., and Riley, B. B. (2006). Zebrafish pax5 regulates development of the utricular macula and vestibular function. Dev. Dynam. 235, 3026-3038. Phillips, B.T., Kwon, H.-J., Melton, C., Houghtaling, P., Fritz, A., and Riley, B. B. (2006). Zebrafish msxB, msxC and msxE function together to refine the neural-nonneural border and regulate cranial placodes and neural crest development. Dev. Biol. 294, 376-390. Mackereth, M. D., Kwak, S.-J., Fritz, A. and Riley, B. B. (2005). Zebrafish pax8 is required for otic placode induction and plays a redundant role with Pax2 genes in the maintenance of the otic placode. Development 132 , 371-382. Riley, B. B. , Chiang, M.-Y., Storch, E., Heck, R., Buckles, G. R. and Lekven, A. C. (2004). Rhombomere boundaries are Wnt signaling centers that regulate metameric patterning in the zebrafish hindbrain. Dev. Dyn. 231 , 278-291. Phillips, B. T., Storch, E. M., Lekven, A. C. and Riley, B. B. (2004). Fgf but not Wnt plays a direct role in otic placode induction. Development 131 , 923-931. Riley, B. B. and Phillips, B. T. (2003). Ringing in the new ear: Resolution of cell interactions in otic development. Dev. Biol . 261 , 289-312. Kwak, S.J., Phillips, B. T., Heck, R. and Riley B. B. (2002). An expanded domain of fgf3 expression in the hindbrain of zebrafish valentino mutants results in mispatterning of the otic vesicle. Development 129 , 5279-5287. Whitfield, T. T., Riley, B. B. , Chiang, M.-Y., and Phillips, B. T. (2002). Development of the zebrafish inner ear. Dev. Dyn. 223 , 427-458.Riley, B.B., B.T. Phillips, K. Bolding. 2001. Zebrafish fgf3 and fgf8 encode redundant functions required for otic placode induction. Dev. Biol. 235, 351-365. Riley, B. B. and S.J. Moorman. 2000. Development of utricular otoliths, but not saccular otoliths, is necessary for vestibular function and survival. J. Neurobiol. 43: 329-337. Riley, B. B., M.-Y. Chiang, L. Farmer, and R. Heck. 1999. The deltaA gene of zebrafish mediates lateral inhibition of hair cells in the inner ear and is regulated by pax2.1. Development 126: 5669-5678. Riley, B.B., B. Appel, A. Fritz, M. Westerfield, D.J. Grunwald, J.S. Eisen. 1999. Delta-mediated specification of midline cell fates in zebrafish embryos. Current Biology 9: 247-256. Riley, B.B., E.S. Mendonsa. 1999. Genetic analysis of tissue-interactions required for otic placode induction in the zebrafish. Dev. Biol. 206: 100-112. Riley, B. B., C. Zhu, C. Janetopoulos, and K.J. Aufderheide. 1997. A critical period of ear development controlled by distinct populations of ciliated cells in the zebrafish. Dev. Biol.191: 191-201. Riley, B. B. and D.J. Grunwald. 1996. A mutation in zebrafish affecting a localized cellular function required for normal ear development. Dev. Biol. 179: 427-435. |
The primary focus of research is on inner ear and hindbrain development. These tissues undergo complex morphogenesis and produce a wide variety of cell types arrayed in intricate spatial patterns. A prominent aspect of our research is to investigate how cell-cell interactions control these developmental processes. Specific interests are as follows:
Hindbrain development: The hindbrain is overtly segmented during early development. Each hindbrain segment (rhombomere) has a unique identity with characteristic cell types, but there are also a series of common cell types produced in all rhombomeres. We are studying how Wnt, Fgf and Delta-Notch signals interact to coordinate both aspects of hindbrain segmentation. Several Wnt and Fgf genes are restricted to specific rhombomeres and help regulate regional identities. As neural development proceeds, Wnt genes are preferentially expressed at rhombomere boundaries, and these domains are maintained by flanking stripes of Delta expression (Fig 2).