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Effects of seawater exchange, pH and carbon supply on the growth of Gracilaria tikvahiae (Rhodophyceae) in large-scale cultures
Title
Effects of seawater exchange, pH and carbon supply on the growth of Gracilaria tikvahiae (Rhodophyceae) in large-scale cultures.
Creator
DeBusk, T. A., Ryther, John H., Harbor Branch Oceanographic Institute
Date Issued
1984
PURL
http://purl.flvc.org/fau/fd/FA00007019
Subject Headings
Gracilaria, Algae culture, Seawater, Hydrogen-ion concentration, Carbon
Format
Document (PDF)
The Dynamic pH Landscape At The Drosophila NMJ Synaptic Cleft And Its Implication In Neurotransmission
Title
The Dynamic pH Landscape At The Drosophila NMJ Synaptic Cleft And Its Implication In Neurotransmission.
Creator
Hernandez, Roberto X., Macleod, Gregory T., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description
The intricate processes governing cellular pH and its impact on protein and cellular function have been extensively explored. However, our understanding of the pH fluctuations that occur during routine cellular activities and their potential to modulate cell function remains, particularly within the highly dynamic pH landscape of a synapse. Investigating the scale, directionality, and temporal characteristics of these activity-dependent pH fluctuations at synapses is of paramount interest, as...
Show moreThe intricate processes governing cellular pH and its impact on protein and cellular function have been extensively explored. However, our understanding of the pH fluctuations that occur during routine cellular activities and their potential to modulate cell function remains, particularly within the highly dynamic pH landscape of a synapse. Investigating the scale, directionality, and temporal characteristics of these activity-dependent pH fluctuations at synapses is of paramount interest, as it carries profound implications for neurotransmitter release and signal transduction. Employing both empirical and computational modeling methods, our research explores the dynamic pH environment within the synaptic cleft of Drosophila glutamatergic motor neuron Ib terminals during synaptic activity and reveals its significance in modulating neurotransmission. Contrary to popular belief, we discovered that these terminals undergo activity-dependent extracellular alkalinization in response to both single action potentials and burst stimulation. This surprising phenomenon was also observed at the mouse calyx of Held. We found activity-dependent alkalinization to be predominantly driven by Ca2+ movement across the postsynaptic membrane, and by targeting pH indicators to subcellular domains, we identified alkalinization to primarily occur within the cleft.
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Date Issued
2023
PURL
http://purl.flvc.org/fau/fd/FA00014346
Subject Headings
Neurotransmission, Drosophila, Hydrogen-Ion Concentration, Motor Neurons, Optogenetics
Format
Document (PDF)
pH Dynamics within the Drosophila Synaptic Cleft During Activity
Title
pH Dynamics within the Drosophila Synaptic Cleft During Activity.
Creator
Feghhi, Touhid, Lau, Andy W.C., Macleod, Gregory T., Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description
Acute pH sensitivity of many neural mechanisms highlights the vulnerability of neurotransmission to the pH of the extracellular milieu. The dogma is that the synaptic cleft will acidify upon neurotransmission because the synaptic vesicles corelease neurotransmitters and protons to the cleft, and the direct data from sensory ribbon-type synapses support the acidification of the cleft. However, ribbon synapses have a much higher release probability than conventional synapses, and it’s not...
Show moreAcute pH sensitivity of many neural mechanisms highlights the vulnerability of neurotransmission to the pH of the extracellular milieu. The dogma is that the synaptic cleft will acidify upon neurotransmission because the synaptic vesicles corelease neurotransmitters and protons to the cleft, and the direct data from sensory ribbon-type synapses support the acidification of the cleft. However, ribbon synapses have a much higher release probability than conventional synapses, and it’s not established whether conventional synapses acidify as well. To test the acidification of the cleft in the conventional synapse, we used genetically encoded fluorescent pH reporters targeted to the synaptic cleft of Drosophila larvae. We observed alkalinization rather than acidification during activity, and this alkalinization was dependent on the exchange of protons for calcium at the postsynaptic membrane. A reaction-diffusion computational model of the pH dynamics at the Drosophila larval neuromuscular junction was developed to leverage the experimental data. The model incorporates the release of glutamate, ATP, and protons from synaptic vesicles into the cleft, PMCA activity, bicarbonate, and phosphate buffering systems. By means of numerical simulations, we reveal a highly dynamic pH landscape within the synaptic cleft, harboring deep but exceedingly rapid acid transients that give way to a prolonged period of alkalinization.
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Date Issued
2023
PURL
http://purl.flvc.org/fau/fd/FA00014221
Subject Headings
Synapses, pH (Chemistry), Hydrogen-ion concentration., Synaptic Transmission, Drosophila
Format
Document (PDF)