A5067670313- Neurobiology and Insect Physiology Research
- Circadian rhythm and melatonin
- Developmental Biology and Gene Regulation
- Photoreceptor and optogenetics research
- Invertebrate Immune Response Mechanisms
- Retinal Development and Disorders
- Neurotransmitter Receptor Influence on Behavior
- Plant Molecular Biology Research
- Pluripotent Stem Cells Research
- Genetics, Aging, and Longevity in Model Organisms
- Receptor Mechanisms and Signaling
- Wnt/β-catenin signaling in development and cancer
- Neuroscience and Neuropharmacology Research
- Neurogenesis and neuroplasticity mechanisms
- Sleep and Wakefulness Research
- Chronic Kidney Disease and Diabetes
- Peroxisome Proliferator-Activated Receptors
- Health disparities and outcomes
- Nitric Oxide and Endothelin Effects
- Nerve injury and regeneration
- Stress Responses and Cortisol
- Reproductive Physiology in Livestock
- Adenosine and Purinergic Signaling
- Hormonal and reproductive studies
- Cellular Mechanics and Interactions
University of Virginia
2009-2024
U.S. National Science Foundation
2000-2002
Foundation Center
2000-2002
Morehouse School of Medicine
2000
McGill University
1998
Virologie et Immunologie Moléculaires
1993
Both dopamine and melatonin are important for the regulation of retinal rhythmicity, substantial evidence suggests that these two substances mutually inhibitory factors act as chemical analogs day night. A circadian oscillator in mammalian retina regulates synthesis. Here we show a rhythm content mouse retina, examine role its control. Using high-performance liquid chromatography (HPLC), measured levels major metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) homovanillic (HVA), retinas...
Abstract Dopamine, the predominant retinal catecholamine, is a neurotransmitter and neuromodulator known to regulate light‐adaptive processes. Because dopamine influences several rhythmic events in retina it also candidate for circadian signal. Using high performance liquid chromatography (HPLC), we have tested whether its breakdown products are Royal College of Surgeons (RCS) rats with normal dystrophic retinas. In both mutant animals entrained 12‐h light/12‐h dark cycle, found robust daily...
The mammalian circadian system is orchestrated by a master pacemaker in the brain, but many peripheral tissues also contain independent or quasi-independent oscillators. adaptive significance of clocks these structures must lie, large part, phase relationships between constituent oscillators and their micro- macroenvironments. To examine relationship postnatal development, which dependent on endogenous programs maternal/environmental influences, oscillators, authors assessed pineal, liver,...
Abstract The firing of hypothalamic hypocretin/orexin neurons is vital for normal sleep–wake transitions, but its molecular determinants are not well understood. It was recently proposed that TASK (TWIK‐related acid‐sensitive potassium) channels [TASK1 (K 2P 3.1) and/or TASK3 9.1)] regulate neuronal and may contribute to the specialized responses orexin glucose pH. Here we tested these theories by performing patch‐clamp recordings from directly identified targeted green fluorescent protein...
Mice lacking the visual cycle enzymes RPE65 or lecithin-retinol acyl transferase (Lrat) have pupillary light responses (PLR) that are less sensitive than those of mice with outer retinal degeneration (rd/rd rdta). Inner photoresponses mediated by melanopsin-expressing, intrinsically photosensitive ganglion cells (ipRGCs), suggesting melanopsin-dependent photocycle utilizes and Lrat. To test this hypothesis, we generated rpe65(-/-); rdta lrat(-/-); rd/rd mutant mice. Unexpectedly, both...
Intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin (OPN4), together with rods and cones, provide light information driving nonvisual responses. We examined photoreception in mice lacking RPE65, a protein that is required for regeneration of visual chromophore cones. Although Rpe65 knockouts retain small degree rod function, we show here circadian phase shifting responses −/− are attenuated far beyond what has been reported rodless/coneless...
In mammals, light input from the retina entrains central circadian oscillators located in suprachiasmatic nuclei (SCN). The phase of activity rhythms with respect to external light:dark cycle is reversed diurnal and nocturnal species, although SCN relative remains unchanged. Neural mechanisms downstream are therefore believed determine diurnality or nocturnality. Here, we report a switch entrainment double-knockout mice lacking inner-retinal photopigment melanopsin (OPN4) RPE65, key protein...
Stem cells enter and exit quiescence as part of normal developmental programs to maintain tissue homeostasis in adulthood. Although it is clear that stem cell intrinsic extrinsic cues, local systemic, regulate quiescence, remains unclear whether cues coordinate control how cue coordination achieved. Here, we report Notch signaling coordinates neuroblast temporal with nutrient Drosophila. When activity reduced, delayed or altogether bypassed, some neuroblasts dividing continuously during the...
Abstract The neurogenic period, where neural stem cells (NSCs) proliferate to produce molecularly distinct progeny in the developing brain, is a critical time of growth many organisms. Proper brain development crucial for survival and requires strict regulation NSC divisions along set developmental timeline. In Drosophila NSCs known as neuroblasts (NBs), cell intrinsic programs integrate with extrinsic cues control periods rapid through temporal patterning genes. Without regulation, can...
Pineal glands removed from neonatal rats at 5, 7, and 9 days of age explanted into short-term culture, synthesized melatonin when stimulated with norepinephrine (NE); their synthesis could not be suppressed bright white light. Dispersed pineal cell cultures or explants prepared 1-day-old neonates held in culture for 7 also NE, but these cases was significantly by light, demonstrating that the pineals had become photosensitive while culture. The development photosensitivity partially...
Correct positioning of stem cells within their niche is essential for tissue morphogenesis and homeostasis. Yet how acquire maintain position remains largely unknown. Here, we show that a subset brain neuroblasts (NBs) in Drosophila utilize PI3-kinase DE-cadherin to build adhesive contact NB positioning. NBs remain native microenvironment when levels activity are elevated NBs. This occurs through dependent regulation DE-Cadherin mediated cell adhesion between neighboring cortex glia, GMC...
Neuroblasts in Drosophila divide asymmetrically, sequentially expressing a series of intrinsic factors to generate diversity neuron types. These known as temporal dictate timing neuroblast transitions response steroid hormone signaling and specify early versus late fates progeny. After completing their programs, neuroblasts differentiate or die, finalizing both number type within each lineage. From screen aimed at identifying genes required terminate divisions, we identified Notch pathway...
Neuroblasts in Drosophila divide asymmetrically, sequentially expressing a series of intrinsic factors to generate diversity neuron types. These known as temporal dictate timing neuroblast transitions response steroid hormone signaling and specify early versus late fates progeny. After completing their programs, neuroblasts differentiate or die, finalizing both number type within each lineage. From screen aimed at identifying genes required terminate divisions, we identified Notch pathway...
Correct positioning of stem cells within their niche is essential for tissue morphogenesis and homeostasis. How acquire maintain position remains largely unknown. Here, we show that a subset brain neuroblasts (NBs) in Drosophila utilize Phosphoinositide 3-kinase (PI3-kinase) DE-cadherin to build adhesive contact NB positioning. NBs remain native microenvironment when levels PI3-kinase activity are elevated NBs. This occurs through PI3-kinase-dependent regulation DE-Cadherin-mediated cell...