David J. Earnest, Ph.D.
Professor
Department of Neuroscience and Experimental Therapeutics
Interdisciplinary Program in Neuroscience (TAMU/TAMHSC)
Phone: 979-862-3109
Email: dearnest@tamu.edu
Biosketch (PDF)
Research Interests
Cellular and Molecular Neurobiology of the Mammalian Circadian
The internal biological clock responsible for the generation of mammalian circadian rhythms and their entrainment to light:dark cycles is located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. The endogenous timekeeping function of the SCN is complemented by its role in mediating the entrainment or synchronization of mammalian circadian rhythms to light-dark cycles. Research in my laboratory employs multidisciplinary approaches to study the cellular and molecular components of the circadian clock mechanism in the SCN and the signal transduction pathway responsible for circadian photoentrainment. The aims of current projects are to: 1) determine the role of neurotrophins in the entrainment of circadian rhythms by light signals; 2) study the molecular clockworks in the SCN and its output signals that drive circadian rhythms in other cells; 3) determine how molecular components of the clock mechanism, the cellular organization of the SCN and circadian behavior are affected: a) by developmental alcohol exposure in an animal model for Fetal Alcohol Syndrome (FAS); and b) by aging; and 4) examine the role of molecular elements of the circadian clockworks in toxin metabolism and mammary gland carcinogenesis.
Research Interests
Techniques:
- Explant and dissociated cell cultures
- Establishment of immortalized neural cell lines
- Gene transfer using retroviral vectors
- RT-PCR and in situ hybridization analysis of mRNA expression in brain tissue
- Immunocytochemistry and radioimmunoassay for neuropeptides
- Neural transplantation of fetal tissue and immortalized cells
- Analysis of rodent wheel-running behavior
Facilities:
- Facilities and equipment necessary for performing cell culture, immunocytochemical, radioimmunoassay and molecular methodologies;
- Computer-based data Acquisition System for Monitoring Locomotor Behavior, Body Temperature and Heart Rate.
I participate in graduate training as a member of the faculty in the Interdisciplinary Program in Neuroscience.
Selected Publications
Farnell, YZ, Allen, GC, Nahm, SS, Neuendorff, N, West, JR, Chen, WJ and Earnest, DJ. (2008) "Neonatal alcohol exposure differentially alters clock gene oscillations within the suprachiasmatic nucleus, cerebellum and liver of adult rats". Alcohol. Clin. Exp. Res. 32: 544-552.
Qu, X, Metz, RP, Porter, WW, Cassone, VM and Earnest, DJ. (2007) "Disruption of clock gene expression alters responses of the AhR signaling pathway in the mouse mammary gland". Mol. Pharm., in press. 72:1349-58.
Menger, GJ, Allen, GC, Neuendorff, N, Nahm, SS, Thomas, T, Cassone, VM and Earnest, DJ. (2007) "Circadian profiling of the transcriptome in NIH/3T3 fibroblasts: comparison with rhythmic gene expression in SCN2.2 cells and the rat SCN".Physiological Genomics 29: 280-9.
Metz, RP, Qu, X, Laffin, B, Earnest D and Porter, WW. (2006) "Circadian clock and cell cycle gene expression in mouse mammary epithelial cells and in the developing mouse mammary gland". Devel. Dynamics 235: 263-271.
Allen, GC, Farnell, YZ, Maeng, JU, West, JR, Chen, WJ and Earnest, DJ. (2006) "Long-term effects of neonatal alcohol exposure on photic re-entrainment and phase–shifting responses of the activity rhythm in adult rats". Alcohol 37: 79-88.
Allen, GC and Earnest, DJ. (2005) "Localization of TrkB immunoreactivity in the retinohypothalamic tract and suprachiasmatic nucleus of the rat". Neurosci.Lett.376:200-204
Allen, GC and Earnest, DJ. (2005) "TrkB-deficient mice show diminished phase shifts of the circadian activity rhythm in response to light".Neurosci. Lett. 378:150-155
Menger, GJ, Lu, K, Thomas, T, Cassone, VM and Earnest, DJ. (2005) "Circadian profiling of the transcriptome in immortalized rat SCN cells". Physiol. Genomics 21:370-381.
Earnest, DJ and Cassone, VM. (2005) "Cell culture models for oscillator and pacemaker function: Recipes for dishes with circadian clocks?"Meth.Enzymol. 393:556-576.
Bell-Pedersen, D, Cassone, VM, Earnest, DJ, Golden, SS, Hardin, PE, Thomas, TL and Zoran, MJ. (2005) "Circadian rhythms from multiple oscillators: Lessons from diverse organisms".Nature Rev.Genetics6:544-556.
Nahm, SS, Farnell, YZ, Griffith, WH and Earnest, DJ. (2005) "Circadian regulation and function of voltage-dependent calcium-channels in the suprachiasmatic nucleus".J. Neurosci. 25: 9304-9308.
Rivera-Bermúdez, MA, Masana, MI, Brown, GM, Earnest, DJ and Dubocovich, ML. (2004) "Immortalized cells from the rat suprachiasmatic nucleus express functional melatonin receptors". Brain Res. 1002:21-27.
Allen, GC, West, JR, Chen, WJ and Earnest, DJ. (2004) "Developmental alcohol exposure disrupts circadian regulation of BDNF in the rat suprachiasmatic nucleus". Neurotoxicol. Teratol. 26:353-358.
Farnell, YZ, West, JR, Chen, WJ, Allen, GC and Earnest, DJ. (2004) "Developmental alcohol exposure alters light-induced phase shifts of the circadian activity rhythm in rats". Alcohol. Clin. Exp. Res. 28:1020-1027.
Allen, GC, Farnell, Y, Bell-Pedersen, D, Cassone , VM and Earnest, DJ. (2004) "Effects of altered Clock gene expression on the pacemaker properties of SCN2.2 cells and oscillatory properties of NIH/3T3 cells". Neuroscience 127:989-999.
Gerdin, MJ, Rivera-Bermúdez, MA, Masana, MI, Earnest, DJ, Gillette, MU and Dubocovich, ML. (2004) "Melatonin desensitizes endogenous MT melatonin receptors in the rat suprachiasmatic nucleus: relevance for defining the periods of sensitivity of the mammalian circadian clock to melatonin". FASEB J. 18:1646-56.
