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Rajan D, Makushok T, Kalish A, Acuna L, Bonville A, Correa Almanza K, Garibay B, Tang E, Voss M, Lin A, Barlow K, Harrigan P, Slabodnick MM, Marshall WF. Single-cell analysis of habituation in Stentor coeruleus. Curr Biol 2023; 33:241-251.e4. [PMID: 36435177 PMCID: PMC9877177 DOI: 10.1016/j.cub.2022.11.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 09/26/2022] [Accepted: 11/03/2022] [Indexed: 11/26/2022]
Abstract
Although learning is often viewed as a unique feature of organisms with complex nervous systems, single-celled organisms also demonstrate basic forms of learning. The giant ciliate Stentor coeruleus responds to mechanical stimuli by contracting into a compact shape, presumably as a defense mechanism. When a Stentor cell is repeatedly stimulated at a constant level of force, it will learn to ignore that stimulus but will still respond to stronger stimuli. Prior studies of habituation in Stentor reported a graded response, suggesting that cells transition through a continuous range of response probabilities. By analyzing single cells using an automated apparatus to deliver calibrated stimuli, we find that habituation occurs via a single step-like switch in contraction probability within each cell, with the graded response in a population arising from the random distribution of switching times in individual cells. This step-like response allows Stentor behavior to be represented by a simple two-state model whose parameters can be estimated from experimental measurements. We find that transition rates depend on stimulus force and also on the time between stimuli. The ability to measure the behavior of the same cell to the same stimulus allowed us to quantify the functional heterogeneity among single cells. Together, our results suggest that the behavior of Stentor is governed by a two-state stochastic machine whose transition rates are sensitive to the time series properties of the input stimuli.
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Affiliation(s)
- Deepa Rajan
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Tatyana Makushok
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Asa Kalish
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Lilibeth Acuna
- CCC Summer course, Center for Cellular Construction, San Francisco State University, San Francisco, CA, USA
| | - Alex Bonville
- CCC Summer course, Center for Cellular Construction, San Francisco State University, San Francisco, CA, USA
| | - Kathya Correa Almanza
- CCC Summer course, Center for Cellular Construction, San Francisco State University, San Francisco, CA, USA
| | - Brenda Garibay
- CCC Summer course, Center for Cellular Construction, San Francisco State University, San Francisco, CA, USA
| | - Eric Tang
- CCC Summer course, Center for Cellular Construction, San Francisco State University, San Francisco, CA, USA
| | - Megan Voss
- CCC Summer course, Center for Cellular Construction, San Francisco State University, San Francisco, CA, USA
| | - Athena Lin
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Kyle Barlow
- Integrative Program in Quantitative Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Patrick Harrigan
- Integrative Program in Quantitative Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Mark M Slabodnick
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Wallace F Marshall
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
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Fabczak S, Fabczak H, Tao N, Song PS. Photosensory transduction in ciliates. I. An analysis of light-induced electrical and motile responses in Stentor coeruleus. Photochem Photobiol 1993; 57:696-701. [PMID: 8506399 DOI: 10.1111/j.1751-1097.1993.tb02940.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Light-induced membrane potential changes and motile responses have been studied in Stentor cells with intracellular microelectrodes and video microscopy, respectively. Intracellular microelectrode recordings showed that step-up increase in light intensity induced an electrical membrane response which consisted of an initial membrane depolarization (photoreceptor potential) followed by an action potential and maintaining phase of depolarization (afterdepolarization). The amplitude of the receptor potential is dependent on the intensity of light stimulus and the action potential appears with a lag period (latency) after the onset of light stimulus. The extent of the membrane afterdepolarization is dependent on the intensity and duration of stimulus used. A close time correlation has been established between the latency for the action potential and the onset of ciliary reversal (stop response). A time correlation was also observed between the duration of the membrane afterdepolarization and the duration of backward swimming. The action spectrum for the photoreceptor potential amplitude of Stentor resembled the action spectra for the latency of ciliary reversal and the photoresponsiveness, indicating that the photomovement response and membrane potential changes are coupled through the same photosensor system. A hypothesis on the photosensory transduction chain in Stentor is discussed according to which the photoreceptors and the ciliary apparatus is mediated by the membrane potential changes.
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Affiliation(s)
- S Fabczak
- Department of Cell Biology, Polish Academy of Sciences, Warsaw
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Thomas C, MacGill RS, Miller GC, Pardini RS. Photoactivation of hypericin generates singlet oxygen in mitochondria and inhibits succinoxidase. Photochem Photobiol 1992; 55:47-53. [PMID: 1603850 DOI: 10.1111/j.1751-1097.1992.tb04208.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Photosensitized inhibition of mitochondrial succinoxidase by hypericin was measured in vitro and found to be drug-dose, light-dose, and wavelength dependent. Singlet oxygen generation, monitored using the singlet oxygen trap tetramethylethylene, and oxygen consumption in isolated mitochondria sensitized by hypericin were also light-dose and wavelength dependent. Unequivocal evidence for the generation of singlet oxygen was obtained using kinetic isotope ratios of products from the reaction between singlet oxygen and geminally deuterated tetramethylethylene. An action spectrum for the inhibition of succinoxidase was measured at wavelengths between 400 and 700 nm and found to parallel the recorded visible absorption spectrum of hypericin in isolated mitochondria. The greatest singlet oxygen generation, oxygen consumption, and succinoxidase inhibition occurred with white light or 600 nm irradiation. These data are consistent with a type II singlet-oxygen-mediated mechanism for hypericin induced photosensitized inhibition of mitochondrial succinoxidase.
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Affiliation(s)
- C Thomas
- Allie M. Lee Laboratory for Cancer Research, University of Nevada, Reno 89557-0014
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