Our research goal is to identify and define the cellular and molecular mechanisms involved in generating and maintaining the functional morphology of vertebrate photoreceptors. We use zebrafish as our primary model organism for this research.
Vertebrate photoreceptors are specialized light sensing neurons. The photoreceptor outer segment is a highly modified cilium where photons of light are transduced into a chemical and electrical signal. The outer segment has the typical cilary axoneme but, in addition, it has a large number of densely packed, stacked, intramembranous discs. The molecular and cellular mechanisms that contribute to vertebrate photoreceptor outer segment morphogenesis are still largely unknown. Unlike typical cilia, the outer segment is continuously regenerated or renewed throughout the life of the animal through the combined process of distal outer segment shedding and proximal outer segment growth. The process of outer segment renewal was discovered over forty years ago, but we still lack an understanding of how photoreceptors renew their outer segments and few, if any, molecular mechanisms that regulate outer segment growth or shedding have been described. Our lack of progress in understanding how photoreceptors renew their outer segments has been hampered by the difficulty in measuring rates of renewal. We have created a new method that uses heat-shock induction of a fluorescent protein that can be used to rapidly measure outer segment growth and renewal rates. In addition we have created a rod-specific inducible transgenic system to manipulate gene expression in zebrafish. With these tools and genome editing techniques, we are uniquely positioned to begin identifying important mechanisms of rod outer segment renewal and, importantly, we will be positioned to test whether it is possible to prolong vision by maintaining outer segment length in retinal degeneration diseases by stimulating growth or suppressing shedding.
Learn more at www.bio.umass.edu/biology/jensen/
- BA University of California, San Diego, 1988
- PhD University of Wisconsin, Madison, 1992
- Postdoctoral Training: University College London, 1992-1996, University of Oregon, 1996-2002