Morphology and cytoskeletal elements of reticulospinal neurons of lampreys in cell culture [abstract]

Abstract only availableFaculty Mentor: Andrew D. McClellan, Biological SciencesSevere spinal cord injury (SCI) disrupts descending axons from reticulospinal (RS) neurons that project to the spinal cord. In most "higher" vertebrates, including humans, recovery is very minimal due to limited regeneration in the central nervous system, and paralysis is usually permanent below the injury site. In several lower vertebrates, including the lamprey, behavioral recovery is almost complete following SCI due to robust axonal regeneration. To study the cellular and molecular mechanisms that regulate axonal regeneration, neurons are often isolated in cell culture so that the factors that influence neurite outgrowth can be studied under controlled conditions. The focus of this project was to determine the morphology and cytoskeletal elements of growth cones of lamprey RS neurons in cell culture. Our research thus far has been focused on determining the molecular and cellular mechanism in which the lamprey uses for neurite regeneration. This research will give more insight into the structural mechanism used during regeneration. It will give some clues as to what structures are useful for the lamprey during the regeneration time by comparing the morphology and cytoskeletal elements of growing neurons versus non-growing neurons. Data was collected for 24 different RS neuron processes and an image analysis program was used to determine the length of the process, the average growth/retraction rate, the soma diameter, the number of filopodia, the number of days in culture, and the number of processes. From our results, we have found that the average growth/retraction rates of RS neurons of lampreys in cell culture are not correlated with the number of filopodia, the number of processes, the length of the processes, the soma diameter, or the age of the neuron. Future studies will be done with a larger number of growth cones of lamprey RS neurons to further confirm our conclusions. Experiments labeling acting, microtubules, and neurofilaments will allow us to determine the effects of intracellular morphology on growth rate.Life Sciences Undergraduate Research Opportunity Progra

Demographic study of craniosynostosis patients in mid-Missouri

Craniosynostosis is a congenital defect in which one or more of the cranial sutures close prematurely, affecting 1 in 2000 to 2500 live births worldwide. Historically, sagittal craniosynostosis has been reported to be the most common form of single-suture craniosynostosis. Our previous retrospective review of craniosynostosis at our institution reported that the incidence of metopic craniosynostosis in mid-Missouri is significantly greater than that of sagittal craniosynostosis, 65% versus 13% (Table 1). Our current aim is to further investigate the demographic characteristics of our institution's craniosynostosis population

The mechanism by which potassium causes neurite retraction in lamprey descending neurons in cell culture

Abstract only availableSevere spinal cord injury (SCI) disrupts descending axons from reticulospinal (RS) neurons that project to the spinal cord. In most “higher” vertebrates, including humans, recovery is very minimal due to limited regeneration in the central nervous system, and paralysis is usually permanent below the injury site. In several lower vertebrates, including the lamprey, behavioral recovery is almost complete following SCI due to robust axonal regeneration. To study the cellular and molecular mechanisms that regulate axonal regeneration, neurons are often isolated in cell culture so that the factors that influence neurite outgrowth can be studied under controlled conditions. In our laboratory, we have developed a cell culture system in which neurite outgrowth of RS neurons can be studied (Hong et al., 2002; Ryan et al., 2004). Application of glutamate, an excitatory neurotransmitter, to the growth cones of RS neurons results in neurite retraction, presumably because of depolarization, calcium influx, and an increase in intracellular calcium. Intracellular calcium is thought to be one of the important regulators of the rate and direction of neurite outgrowth. Calcium influx could result from at least two different channels: chemically-gated channels (e.g. NMDA channels); or voltage-gated calcium channels. The purpose of the present study was to determine if calcium influx via voltage-gated calcium channels is sufficient to elicit neurite retraction. First, focal application of a 31 M potassium to growth cones of DiI-labeled RS neurons in culture to open voltage-gated calcium channels significantly reduced neurite growth rates, including neurite retraction, compared to pre-control periods. Second, 2 of Co++ or 300 M Cd++, which block calcium channels, abolished potassium-induced neurite retraction. In conclusion, the results suggest that calcium influx via voltage-gated calcium channels is sufficient to cause neurite retraction. Other experiments will determine if influx through voltage-gated channels is necessary for glutamate to elicit neurite outgrowth. Determination of the factors that regulate neurite outgrowth may provide information about the mechanism by which RS neurons regenerate their axons following spinal cord injury and restore locomotor function.Life Sciences Undergraduate Research Opportunity Progra