Janis Weeks

Professor, Department of Biology
B.S., 1975, Massachusetts Institute of Technology
Ph.D., 1980, University of California, San Diego

Research Interests

Effects of steroid hormones on neural circuits and behavior; synaptic plasticity; programmed cell death; segmental identity

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The major focus of our research is to understand how hormones influence the structure and function of individual neurons, from the molecular to the behavioral level. We investigate this issue in the hawkmoth, Manduca sexta (the "white rat of insect endocrinology"), which transforms from caterpillar to pupa to moth in about 6 weeks. More recently, we have expanded our work to include the fruit fly, Drosophila melanogaster , which offers molecular genetic tools. Insect metamorphosis is controlled by steroid hormones, which alter gene expression in target cells. In response to hormonal cues, individual neurons may exhibit dendritic or axonal growth, dendritic or axonal regression and/or programmed cell death (PCD). These effects underlie the reorganization of neural circuits that produce different behaviors in the different life stages. For example, we've determined that steroid-induced changes in neuronal architecture underlie the electrophysiological weakening of synaptic connections during metamorphosis and the accompanying loss of an outmoded larval behavior.

Steroid hormones similarly influence the developing vertebrate nervous system, and steroid hormone receptors are evolutionarily conserved in insects and vertebrates. Our goal is to understand fundamental cellular and molecular mechanisms by which steroids alter neuronal phenotype. We address these issues at the level of individually identified neurons and at synaptic connections between identified pre- and postsynaptic neurons with known behavioral functions. Our work on neurodegeneration is relevant to understanding how steroid hormones influence disorders such as Alzheimer's Disease. We use a variety of experimental methods including cell culture of identified Manduca and Drosophila neurons, electrophysiology in vivo and in vitro (e.g., intracellular recordings and voltage clamp), confocal microscopy (e.g., to study structural changes in mitochondria during PCD) and molecular methods (including subtraction-coupled Manduca cDNA microarrays that we printed at UO).

The Weeks lab is committed to diversity and encourages enquiries from women and members of underrepresented groups.

Representative Reviews

Weeks JC. (2003) Thinking globally, acting locally: steroid hormone regulation of the dendritic architecture, synaptic connectivity and death of an individual neuron. Prog Neurobiol. 70(5): 421-42. Review.

Weeks, J.C. (1999) Metamorphosis as midlife crisis: what to do with the leftover neurons? In The Biology of Early Influences, R.L. Hyson and F. Johnson, eds., Plenum Publishing Corp., New York, pp. 135-151

Weeks, J.C., G.A, Jacobs, J.T. Pierce, D.J. Sandstrom, L.C. Streichert, B.A. Trimmer, D.E. Wiel and E.R. Wood (1997) Neural mechanisms of behavioral plasticity: metamorphosis and learning in Manduca sexta. Brain Behav. Evol. 50(suppl. 1):69-80.

Weeks, J.C. and McEwen, B.S. (1997) Modulation of neural circuits by steroid hormones in rodent and insect model systems. In Neurons, Networks and Motor Behavior, P.S.G. Stein, S. Grillner and A.I. Selverston, eds., The MIT Press, pp. 195-207.

Representative Recent Publications

Hazelett DJ, Weeks JC. (2005) Segment-specific muscle degeneration is triggered directly by a steroid hormone during insect metamorphosis. J Neurobiol . 62( 2 ): 164-77.

Gray, J.R. and J.C. Weeks (2003) Steroid-induced dendritic regression reduces anatomical contacts between neurons during synaptic weakening and the developmental loss of a behavior. J. Neurosci. 23: 1406-1415.

Kinch, G.L., Hoffman, K.L., Rodrigues, E.M., Zee, M.C. and Weeks, J.C. (2003) Steroid-triggered programmed cell death of a motoneuron is autophagic and involves structural alterations in mitochondria. J. Comp. Neurol. 457: 384-403.

Melville, J.M., K.L. Hoffman, H.E. Jarrard and J.C. Weeks (2003) Cell culture of mechanoreceptor neurons innervating proleg hairs in Manduca sexta larvae, and co-culture with target motoneurons. Cell Tissue Res. 311: 117-130.

Hoffman, K.L. and J.C. Weeks (2001) Role of caspases and mitochondria in the steroid-induced programmed cell death of a motoneuron during metamorphosis. Dev. Biol. 229: 517-536.

Zee, M.C. and J.C. Weeks (2001) Developmental change in the steroid hormone signal for cell-autonomous, segment-specific programmed cell death of a motoneuron. Dev. Biol. 235: 45-61.

Novicki, A. and J.C. Weeks (2000) Developmental attenuation of Manduca pre-ecdysis behavior involves neural changes upstream of motoneurons and relay interneurons. J. Comp. Physiol. A 186: 69-79.

Streichert, L.C., J.T. Pierce, J.A. Nelson and J.C. Weeks (1997) Segment-specific programmed cell death of identified motoneurons triggered directly by steroid hormones in vitro. Dev. Biol. 183: 95-107.

Streichert, L.C. and J.C. Weeks (1995) Decreased monosynaptic sensory input to an identified motoneuron is associated with steroid-mediated dendritic regression during metamorphosis in Manduca sexta. J. Neurosci. 15: 1484-1495.

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Janis Weeks

Professor, Department of Biology B.S., 1975, Massachusetts Institute of Technology Ph.D., 1980, University of California, San Diego Research Interests

Representative Reviews

Representative Recent Publications

Professor, Department of Biology
B.S., 1975, Massachusetts Institute of Technology
Ph.D., 1980, University of California, San Diego

Research Interests