Mentoring High School Students

Dr. Robin Cooper is a faculty member in the Department of Biology and teaches physiology and neurobiology courses at the University of Kentucky. His research is in comparative physiology. He received a double major with a B.S. in Chemistry and Zoology from Texas Tech in 1983 and a PhD in Physiology from Texas Tech Medical School in 1989. He has had postdoctoral training in Switzerland and Canada for 7 years before joining the University of Kentucky in 1996

Growth of Stygobitic (\u3cem\u3eOrconectes australis packardi\u3c/em\u3e) and Epigean (\u3cem\u3eOrconectes cristavarius\u3c/em\u3e) Crayfishes Maintained in Laboratory Conditions

This study reports on maintenance and growth of the cave crayfish, Orconectes australis packardi, and the epigean crayfish, Orconectes cristavarius, with laboratory conditions for 1 and 2 years. The O. a. packardi survived well compared to the O. cristavarius in captivity. The poor survival of the epigean species was probably due to unsuitable conditions. The epigean as well as the cave crayfish molted and grew in captivity, but without any significant difference in molt frequency between species. In the first year, total body length was obtained to assay growth, whereas in the second year the more accurate measure of post-orbital carapace length was used. The ability of O. a. packardi to adjust to captivity is likely due to their lower metabolic rate and ability to handle hypoxic stress better than epigean species

Historical View and Physiology Demonstration at the NMJ of the Crayfish Opener Muscle

Here we present some of the key important discoveries made with the opener neuromuscular (NMJ) preparation of crustaceans and illustrate that there is still much to learn from this model preparation. In understanding the history one can appreciate why even today this NMJ still offers a rich playground to address questions regarding pre- and post-synaptic function and plasticity. The viability and ease of access to the terminal for intracellular as well as extracellular electrophysiology and imaging are significant advantages. The mechanisms behind the modulation of vesicular kinetics and fusion within the high- and low-output terminals are begging for investigation. The preparation also offers a testable model system for computational assessments and manipulations to examine key variables in theoretical models of synaptic function, for example calcium dynamics during short-term facilitation. The synaptic complexity of active zone and statistical nature of quantal release is also an open area for future investigation both experimentally and computationally

Cold Exposure Effects on Cardiac Function and Synaptic Transmission at the Neuromuscular Junction in Invertebrates

This review emphasizes how ectothermic animals respond physiologically to environmental temperature changes and cold stress. Generally ectothermic animals cannot generate heat to maintain their body temperature but they can still survive in various temperature zones. Various organisms have been analyzed anatomically and physiologically in the attempt to understand the underlying mechanisms of this temperature adaptation. A few of the changes in the metabolic and molecular function of proteins are discussed. The potential of how hormonal modulation of cardiac and nervous systems which influences responses during exposure cold exposure is also addressed. The focus of this review is on the effect of cold exposure on synaptic transmission and cardiac function in crustaceans and insects

Physiological Recordings of High and Low Output NMJs on the Crayfish Leg Extensor Muscle

We explain in detail how to expose and conduct electrophysiological recordings of synaptic responses for high (phasic) and low (tonic) output motor neurons innervating the extensor muscle in the walking leg of a crayfish. Distinct differences are present in the physiology and morphology of the phasic and tonic nerve terminals. The tonic axon contains many more mitochondria, enabling it to take a vital stain more intensely than the phasic axon. The tonic terminals have varicosities, and the phasic terminal is filiform. The tonic terminals are low in synaptic efficacy but show dramatic facilitated responses. In contrast, the phasic terminals are high in quantal efficacy but show synaptic depression with high frequency stimulation. The quantal output is measured with a focal macropatch electrode placed directly over the visualized nerve terminals. Both phasic and tonic terminals innervate the same muscle fibers, which suggests that inherent differences in the neurons, rather than differential retrograde feedback from the muscle, account for the morphological and physiological differentiation

Actions of NCX, PMCA and SERCA on Short-Term Facilitation and Maintenance of Transmission in Nerve Terminals

Residual Ca2+ can accumulate in the nerve terminal during repetitive stimulation; thus, the basis for short-term facilitation (STF). The plasmalemmal Na+/Ca2+ exchanger [NCX], the Ca2+-ATPase (PMCA) and the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) on the endoplasmic reticulum are three important Ca2+ regulatory processes in controlling [Ca2+]i. The role of these [Ca2+]i regulators in the development and maintenance of STF was addressed at the neuromuscular junction. When the NCX is compromised by reduced [Na+]o, the EPSP amplitudes decrease, but with KB-R7943 (a reverse blocker of NCX) the amplitude increases. Compromising the PMCA with pH 8.8 produces an increase in EPSP amplitudes, but treatments with carboxyeosin (a blocker of PMCA) produced mixed results. Blocking the SERCA increases EPSP amplitudes. Facilitation was only slighted altered in some conditions with these manipulations. The results support the view that release is not saturated during a plateau phase of STF since the terminal is able to reach a new plateau with higher stimulation frequency or an altered [Ca2+]i. Multiple approaches in compromising the NCX and PMCA are presented. These findings are significant because there is a rapid alteration in transmission when compromising Ca2+ extrusion mechanisms during STF