Anne Hansen
Instructor
Ph.D. 1994 University of Hamburg, Germany
Email Anne.Hansen@uchsc.edu
Phone 303-724-3429
Fax 303-724-3420
Mailing address Dept. Cell & Developmental Biology, Mail Stop 8108
Univ. of Colorado Health Sciences Center at
Fitzsimons
Bldg. RC-1, Room L18-11122
12801 East 17th Ave.
P.O.Box 6511
Aurora, CO 80045
Research Interests
My research interests focus on the ultrastructure of the three chemosensory systems: olfaction, taste and solitary chemosensory cells. I use scanning electron microscopic (SEM) and transmission electron microscopic (TEM) techniques to describe the development, distribution and cellular features of receptor cells of the three chemosensory modalities. Furthermore, methods of immunocytochemistry and in-situ hybridization are combined with TEM techniques to determine for instance which cell type expresses what receptor molecule or transduction component. My spectrum of animal models is broad, including fish, frogs, alligators, rodents, and humans.
Olfaction
Olfactory receptor neurons (ORNs) are primary neurons that connect directly to the olfactory bulb, a part of the brain (reviewed in Hansen and Zielinski, J. Neurocytol., 2005). The majority of these ORNs (in most vertebrates, incl. humans) are ciliated cells. However, a second less abundant type of ORN bears microvilli at its apical ending. Recently, I found a third type of ORN, the so-called crypt neuron. This peculiar cell type is present across the group of teleosts (Hansen and Finger, Brain Behav. Evol., 2000) and in the meantime has been described for lampreys, sharks and rays. My preliminary data suggest that this cell type occurs also in higher vertebrates. To further our knowledge of microvillous and crypt olfactory neurons, one of my projects aims at the description of unconventional ORNs in rodents and humans.
Taste
Taste buds are endorgans comprised of different types of secondary neurons innervated by cranial nerves. In rodents these taste bud cells are characterized by their morphology and their expression of various markers, separated into Type I, type II, and type III cells. In fish taste buds these markers are lacking and the cell types are named after their appearance in the electron microscope: dark cells with many small microvilli and light cells with one big villus at their apical ending. Recently, I described a second type of light cell for zebrafish taste buds: a light cell with some small microvilli at their apical ending (Hansen et al., 2002). ATP is a crucial neurotransmitter in rodent taste buds (Finger et al., Science, 2005). Presently we are testing the hypothesis whether ATP also acts as a neurotransmitter in fish taste buds and if so, which cell type(s) are involved.
Solitary Chemosensory Cells
These secondary neurons had been known for fishes and frog tadpoles for over a century, but only recently were they found also in mammals (Finger et al., PNAS, 2003). In rodents these cells act as a detector of irritants. Our studies suggest that several subpopulations of solitary chemosensory cells exist in rodents. Furthermore, they seem to be present also in humans. Current studies at the light and electron microscopic level aim at the characterization of these different subpopulations in rodents and humans.
Selected Publications
Hansen, A. (2007). Two different chemosensory systems in the olfactory epithelium of the American alligator, Alligator mississippiensis. (submitted).
Hansen, A.,Zielinski, B. (2005). Diversity in the olfactory epithelium of bony fishes: development, lamellar arrangement, sensory neuron cell types and transduction components. J. Neurocytol. 34:183-208.
Hansen A, Anderson KT, Finger TE. (2004) Differential distribution of olfactory receptor neurons in goldfish: structural and molecular correlates. J Comp Neurol. 477(4):347-59.
Hansen A, Rolen SH, Anderson K, Morita Y, Caprio J, Finger TE. (2003) Correlation between olfactory receptor cell type and function in the channel catfish. J Neurosci. 23(28):9328-39.
Finger TE, Bottger B, Hansen A, Anderson KT, Alimohammadi H, Silver WL. 2003 Solitary chemoreceptor cells in the nasal cavity serve as sentinels of respiration. Proc Natl Acad Sci U S A. 100(15):8981-6.
Zeiske, E.; Kasumyan, A.; Bartsch, P.; Hansen, A. (2003). Early development of the olfactory organ in sturgeons of the genus Acipenser: a comparative and electron microscopic study. Anat. Embryol. 206: 357-372.
Hansen, A. ; Zeiske, E.; Reutter, K. (2002). Development of taste buds in the zebrafish, Danio rerio. Develop. Dyn. 223:483-496.