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Omond SET, Lesku JA. Why study sleep in flatworms? J Comp Physiol B 2024; 194:233-239. [PMID: 36899149 PMCID: PMC11233290 DOI: 10.1007/s00360-023-01480-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/31/2023] [Accepted: 02/23/2023] [Indexed: 03/12/2023]
Abstract
The behaviors that characterize sleep have been observed across a broad range of different species. While much attention has been placed on vertebrates (mostly mammals and birds), the grand diversity of invertebrates has gone largely unexplored. Here, we introduce the intrigue and special value in the study of sleeping platyhelminth flatworms. Flatworms are closely related to annelids and mollusks, and yet are comparatively simple. They lack a circulatory system, respiratory system, endocrine glands, a coelom, and an anus. They retain a central and peripheral nervous system, various sensory systems, and an ability to learn. Flatworms sleep, like other animals, a state which is regulated by prior sleep/wake history and by the neurotransmitter GABA. Furthermore, they possess a remarkable ability to regenerate from a mere fragment of the original animal. The regenerative capabilities of flatworms make them a unique bilaterally symmetric animal to study a link between sleep and neurodevelopment. Lastly, the recent applications of tools for probing the flatworm genome, metabolism, and brain activity make their entrance into the field of sleep research all the more timely.
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Affiliation(s)
- Shauni E T Omond
- School of Agriculture, Biomedicine & Environment, La Trobe University, Melbourne, Australia.
| | - John A Lesku
- School of Agriculture, Biomedicine & Environment, La Trobe University, Melbourne, Australia.
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Ireland D, Zhang S, Bochenek V, Hsieh JH, Rabeler C, Meyer Z, Collins EMS. Differences in neurotoxic outcomes of organophosphorus pesticides revealed via multi-dimensional screening in adult and regenerating planarians. FRONTIERS IN TOXICOLOGY 2022; 4:948455. [PMID: 36267428 PMCID: PMC9578561 DOI: 10.3389/ftox.2022.948455] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/25/2022] [Indexed: 11/07/2022] Open
Abstract
Organophosphorus pesticides (OPs) are a chemically diverse class of commonly used insecticides. Epidemiological studies suggest that low dose chronic prenatal and infant exposures can lead to life-long neurological damage and behavioral disorders. While inhibition of acetylcholinesterase (AChE) is the shared mechanism of acute OP neurotoxicity, OP-induced developmental neurotoxicity (DNT) can occur independently and/or in the absence of significant AChE inhibition, implying that OPs affect alternative targets. Moreover, different OPs can cause different adverse outcomes, suggesting that different OPs act through different mechanisms. These findings emphasize the importance of comparative studies of OP toxicity. Freshwater planarians are an invertebrate system that uniquely allows for automated, rapid and inexpensive testing of adult and developing organisms in parallel to differentiate neurotoxicity from DNT. Effects found only in regenerating planarians would be indicative of DNT, whereas shared effects may represent neurotoxicity. We leverage this unique feature of planarians to investigate potential differential effects of OPs on the adult and developing brain by performing a comparative screen to test 7 OPs (acephate, chlorpyrifos, dichlorvos, diazinon, malathion, parathion and profenofos) across 10 concentrations in quarter-log steps. Neurotoxicity was evaluated using a wide range of quantitative morphological and behavioral readouts. AChE activity was measured using an Ellman assay. The toxicological profiles of the 7 OPs differed across the OPs and between adult and regenerating planarians. Toxicological profiles were not correlated with levels of AChE inhibition. Twenty-two "mechanistic control compounds" known to target pathways suggested in the literature to be affected by OPs (cholinergic neurotransmission, serotonin neurotransmission, endocannabinoid system, cytoskeleton, adenyl cyclase and oxidative stress) and 2 negative controls were also screened. When compared with the mechanistic control compounds, the phenotypic profiles of the different OPs separated into distinct clusters. The phenotypic profiles of adult vs. regenerating planarians exposed to the OPs clustered differently, suggesting some developmental-specific mechanisms. These results further support findings in other systems that OPs cause different adverse outcomes in the (developing) brain and build the foundation for future comparative studies focused on delineating the mechanisms of OP neurotoxicity in planarians.
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Affiliation(s)
- Danielle Ireland
- Department of Biology, Swarthmore College, Swarthmore, PA, United States
| | - Siqi Zhang
- Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Veronica Bochenek
- Department of Biology, Swarthmore College, Swarthmore, PA, United States
| | - Jui-Hua Hsieh
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Durham, NC, United States
| | - Christina Rabeler
- Department of Biology, Swarthmore College, Swarthmore, PA, United States
| | - Zane Meyer
- Department of Engineering, Swarthmore College, Swarthmore, PA, United States,Department of Computer Science, Swarthmore College, Swarthmore, PA, United States
| | - Eva-Maria S. Collins
- Department of Biology, Swarthmore College, Swarthmore, PA, United States,Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA, United States,Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States,Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, United States,Department of Physics, University of California San Diego, La Jolla, CA, United States,*Correspondence: Eva-Maria S. Collins,
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Birkholz TR, Beane WS. The planarian TRPA1 homolog mediates extraocular behavioral responses to near-ultraviolet light. J Exp Biol 2017; 220:2616-2625. [PMID: 28495872 PMCID: PMC5536891 DOI: 10.1242/jeb.152298] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 05/04/2017] [Indexed: 12/17/2022]
Abstract
Although light is most commonly thought of as a visual cue, many animals possess mechanisms to detect light outside of the eye for various functions, including predator avoidance, circadian rhythms, phototaxis and migration. Here we confirm that planarians (like Caenorhabditis elegans, leeches and Drosophila larvae) are capable of detecting and responding to light using extraocular photoreception. We found that, when either eyeless or decapitated worms were exposed to near-ultraviolet (near-UV) light, intense wild-type photophobic behaviors were still observed. Our data also revealed that behavioral responses to green wavelengths were mediated by ocular mechanisms, whereas near-UV responses were driven by extraocular mechanisms. As part of a candidate screen to uncover the genetic basis of extraocular photoreception in the planarian species Schmidtea mediterranea, we identified a potential role for a homolog of the transient receptor potential channel A1 (TRPA1) in mediating behavioral responses to extraocular light cues. RNA interference (RNAi) to Smed-TrpA resulted in worms that lacked extraocular photophobic responses to near-UV light, a mechanism previously only identified in Drosophila These data show that the planarian TRPA1 homolog is required for planarian extraocular-light avoidance and may represent a potential ancestral function of this gene. TRPA1 is an evolutionarily conserved detector of temperature and chemical irritants, including reactive oxygen species that are byproducts of UV-light exposure. Our results suggest that planarians possess extraocular photoreception and display an unconventional TRPA1-mediated photophobic response to near-UV light.
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Affiliation(s)
- Taylor R Birkholz
- Department of Biological Sciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, MI 49008, USA
| | - Wendy S Beane
- Department of Biological Sciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, MI 49008, USA
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Shettigar N, Joshi A, Dalmeida R, Gopalkrishna R, Chakravarthy A, Patnaik S, Mathew M, Palakodeti D, Gulyani A. Hierarchies in light sensing and dynamic interactions between ocular and extraocular sensory networks in a flatworm. SCIENCE ADVANCES 2017; 3:e1603025. [PMID: 28782018 PMCID: PMC5533540 DOI: 10.1126/sciadv.1603025] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 06/27/2017] [Indexed: 05/23/2023]
Abstract
Light sensing has independently evolved multiple times under diverse selective pressures but has been examined only in a handful among the millions of light-responsive organisms. Unsurprisingly, mechanistic insights into how differential light processing can cause distinct behavioral outputs are limited. We show how an organism can achieve complex light processing with a simple "eye" while also having independent but mutually interacting light sensing networks. Although planarian flatworms lack wavelength-specific eye photoreceptors, a 25 nm change in light wavelength is sufficient to completely switch their phototactic behavior. Quantitative photoassays, eye-brain confocal imaging, and RNA interference/knockdown studies reveal that flatworms are able to compare small differences in the amounts of light absorbed at the eyes through a single eye opsin and convert them into binary behavioral outputs. Because planarians can fully regenerate, eye-brain injury-regeneration studies showed that this acute light intensity sensing and processing are layered on simple light detection. Unlike intact worms, partially regenerated animals with eyes can sense light but cannot sense finer gradients. Planarians also show a "reflex-like," eye-independent (extraocular/whole-body) response to low ultraviolet A light, apart from the "processive" eye-brain-mediated (ocular) response. Competition experiments between ocular and extraocular sensory systems reveal dynamic interchanging hierarchies. In intact worms, cerebral ocular response can override the reflex-like extraocular response. However, injury-regeneration again offers a time window wherein both responses coexist, but the dominance of the ocular response is reversed. Overall, we demonstrate acute light intensity-based behavioral switching and two evolutionarily distinct but interacting light sensing networks in a regenerating organism.
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Affiliation(s)
- Nishan Shettigar
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
- Shanmugha Arts, Science, Technology and Research Academy (SASTRA) University, Tirumalaisamudram, Thanjavur 613401, India
| | - Asawari Joshi
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
| | - Rimple Dalmeida
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
- Shanmugha Arts, Science, Technology and Research Academy (SASTRA) University, Tirumalaisamudram, Thanjavur 613401, India
| | - Rohini Gopalkrishna
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
| | - Anirudh Chakravarthy
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
| | - Siddharth Patnaik
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
| | - Manoj Mathew
- National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
| | - Dasaradhi Palakodeti
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
| | - Akash Gulyani
- Institute for Stem Cell Biology and Regenerative Medicine (inStem), National Centre for Biological Sciences, GKVK Post, Bangalore 560065, India
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DONG Z, YUWEN Y, SIMA Y, DONG Y, ZHAN H, CHEN G, LIU D. Photokinesis andDjopsingene expression analysis during the regeneration of planarian eyes. Integr Zool 2017; 12:157-164. [DOI: 10.1111/1749-4877.12234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Zimei DONG
- College of Life Science; Henan Normal University; Xinxiang Henan China
| | - Yanqing YUWEN
- College of Life Science; Henan Normal University; Xinxiang Henan China
| | - Yingxu SIMA
- College of Life Science; Henan Normal University; Xinxiang Henan China
| | - Yanping DONG
- College of Life Science; Henan Normal University; Xinxiang Henan China
| | - Huina ZHAN
- College of Life Science; Henan Normal University; Xinxiang Henan China
| | - Guangwen CHEN
- College of Life Science; Henan Normal University; Xinxiang Henan China
| | - Dezeng LIU
- College of Life Science; Henan Normal University; Xinxiang Henan China
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Shomrat T, Levin M. An automated training paradigm reveals long-term memory in planarians and its persistence through head regeneration. ACTA ACUST UNITED AC 2013; 216:3799-810. [PMID: 23821717 DOI: 10.1242/jeb.087809] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Planarian flatworms are a popular system for research into the molecular mechanisms that enable these complex organisms to regenerate their entire body, including the brain. Classical data suggest that they may also be capable of long-term memory. Thus, the planarian system may offer the unique opportunity to study brain regeneration and memory in the same animal. To establish a system for the investigation of the dynamics of memory in a regenerating brain, we developed a computerized training and testing paradigm that avoided the many issues that confounded previous, manual attempts to train planarians. We then used this new system to train flatworms in an environmental familiarization protocol. We show that worms exhibit environmental familiarization, and that this memory persists for at least 14 days - long enough for the brain to regenerate. We further show that trained, decapitated planarians exhibit evidence of memory retrieval in a savings paradigm after regenerating a new head. Our work establishes a foundation for objective, high-throughput assays in this molecularly tractable model system that will shed light on the fundamental interface between body patterning and stored memories. We propose planarians as key emerging model species for mechanistic investigations of the encoding of specific memories in biological tissues. Moreover, this system is lik ely to have important implications for the biomedicine of stem-cell-derived treatments of degenerative brain disorders in human adults.
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Affiliation(s)
- Tal Shomrat
- Biology Department and Tufts Center for Regenerative and Developmental Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA
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Abstract
A mechanistic understanding of robust self-assembly and repair capabilities of complex systems would have enormous implications for basic evolutionary developmental biology as well as for transformative applications in regenerative biomedicine and the engineering of highly fault-tolerant cybernetic systems. Molecular biologists are working to identify the pathways underlying the remarkable regenerative abilities of model species that perfectly regenerate limbs, brains, and other complex body parts. However, a profound disconnect remains between the deluge of high-resolution genetic and protein data on pathways required for regeneration, and the desired spatial, algorithmic models that show how self-monitoring and growth control arise from the synthesis of cellular activities. This barrier to progress in the understanding of morphogenetic controls may be breached by powerful techniques from the computational sciences-using non-traditional modeling approaches to reverse-engineer systems such as planaria: flatworms with a complex bodyplan and nervous system that are able to regenerate any body part after traumatic injury. Currently, the involvement of experts from outside of molecular genetics is hampered by the specialist literature of molecular developmental biology: impactful collaborations across such different fields require that review literature be available that presents the key functional capabilities of important biological model systems while abstracting away from the often irrelevant and confusing details of specific genes and proteins. To facilitate modeling efforts by computer scientists, physicists, engineers, and mathematicians, we present a different kind of review of planarian regeneration. Focusing on the main patterning properties of this system, we review what is known about the signal exchanges that occur during regenerative repair in planaria and the cellular mechanisms that are thought to underlie them. By establishing an engineering-like style for reviews of the molecular developmental biology of biomedically important model systems, significant fresh insights and quantitative computational models will be developed by new collaborations between biology and the information sciences.
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Affiliation(s)
| | | | - Michael Levin
- Center for Regenerative and Developmental Biology, and Department of Biology, Tufts University, Medford, Massachusetts, United States of America
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Davidson C, Prados J, Gibson CL, Young AMJ, Barnes D, Sherlock R, Hutchinson CV. Shedding light on photosensitive behaviour in brown planaria (Dugesia Tigrina). Perception 2011; 40:743-6. [PMID: 21936302 DOI: 10.1068/p6949] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The planarian flatworm is one of the simplest animals to develop two eyecups that enable them to detect the presence and direction of light, which they typically avoid. In this study we assessed responses of planaria to different intensities of light. We found that they exhibited a graded, sigmoidal, photonegative response to light intensity. A two-octave increase in luminance (on the upward slope of the sigmoid) corresponded to a 9% increase in the speed planaria travelled to avoid light.
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Affiliation(s)
- Colin Davidson
- Division of Biomedical Sciences, St Georges, University of London, Cranmer Terrace, London SW17 0RE, UK
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9
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Blackiston D, Shomrat T, Nicolas CL, Granata C, Levin M. A second-generation device for automated training and quantitative behavior analyses of molecularly-tractable model organisms. PLoS One 2010; 5:e14370. [PMID: 21179424 PMCID: PMC3003703 DOI: 10.1371/journal.pone.0014370] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 11/23/2010] [Indexed: 11/18/2022] Open
Abstract
A deep understanding of cognitive processes requires functional, quantitative analyses of the steps leading from genetics and the development of nervous system structure to behavior. Molecularly-tractable model systems such as Xenopus laevis and planaria offer an unprecedented opportunity to dissect the mechanisms determining the complex structure of the brain and CNS. A standardized platform that facilitated quantitative analysis of behavior would make a significant impact on evolutionary ethology, neuropharmacology, and cognitive science. While some animal tracking systems exist, the available systems do not allow automated training (feedback to individual subjects in real time, which is necessary for operant conditioning assays). The lack of standardization in the field, and the numerous technical challenges that face the development of a versatile system with the necessary capabilities, comprise a significant barrier keeping molecular developmental biology labs from integrating behavior analysis endpoints into their pharmacological and genetic perturbations. Here we report the development of a second-generation system that is a highly flexible, powerful machine vision and environmental control platform. In order to enable multidisciplinary studies aimed at understanding the roles of genes in brain function and behavior, and aid other laboratories that do not have the facilities to undergo complex engineering development, we describe the device and the problems that it overcomes. We also present sample data using frog tadpoles and flatworms to illustrate its use. Having solved significant engineering challenges in its construction, the resulting design is a relatively inexpensive instrument of wide relevance for several fields, and will accelerate interdisciplinary discovery in pharmacology, neurobiology, regenerative medicine, and cognitive science.
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Affiliation(s)
- Douglas Blackiston
- Biology Department and Center for Regenerative and Developmental Biology, Tufts University, Medford, Massachusetts, United States of America
- Department of Regenerative and Developmental Biology, Forsyth Institute, Boston, Massachusetts, United States of America
| | - Tal Shomrat
- Biology Department and Center for Regenerative and Developmental Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Cindy L. Nicolas
- Biology Department and Center for Regenerative and Developmental Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Christopher Granata
- Boston Engineering Corporation, Waltham, Massachusetts, United States of America
| | - Michael Levin
- Biology Department and Center for Regenerative and Developmental Biology, Tufts University, Medford, Massachusetts, United States of America
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Vreys C, Schockaert ER, Michiels NK. Unusual Pre-copulatory Behaviour in the Hermaphroditic Planarian Flatworm, Dugesia gonocephala (Tricladida, Paludicola). Ethology 2010. [DOI: 10.1111/j.1439-0310.1997.tb00117.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Peters A, Streng A, Michiels NK. Mating Behaviour in a Hermaphroditic Flatworm with Reciprocal Insemination: Do They Assess Their Mates during Copulation? Ethology 2010. [DOI: 10.1111/j.1439-0310.1996.tb01121.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Hicks C, Sorocco D, Levin M. Automated analysis of behavior: a computer-controlled system for drug screening and the investigation of learning. ACTA ACUST UNITED AC 2006; 66:977-90. [PMID: 16779826 DOI: 10.1002/neu.20290] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Efforts to understand cognition will be greatly facilitated by computerized systems that enable the automated analysis of animal behavior. A number of controversies in the invertebrate learning field have resulted from difficulties inherent in manual experiments. Driven by the necessity to overcome these problems during investigation of neural function in planarian flatworms and frog larvae, we designed and developed a prototype for an inexpensive, flexible system that enables automated control and analysis of behavior and learning. Applicable to a variety of small animals such as flatworms and zebrafish, this system allows automated analysis of innate behavior, as well as of learning and memory in a plethora of conditioning paradigms. We present here the schematics of a basic prototype, which overcomes experimenter effects and operator tedium, enabling a large number of animals to be analyzed with transparent on-line access to primary data. A scaled-up version of this technology represents an efficient methodology to screen pharmacological and genetic libraries for novel neuroactive reagents of basic and biomedical relevance.
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Affiliation(s)
- Caitlin Hicks
- Forsyth Center for Regenerative and Developmental Biology, The Forsyth Institute, Boston, Massachusetts 02115, USA
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13
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Evidence for unconditional sperm transfer and sperm-dependent parthenogenesis in a hermaphroditic flatworm (Girardia tigrina) with fissipary. J Zool (1987) 2002. [DOI: 10.1017/s095283690200064x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Azuma K, Iwasaki N, Ohtsu K. Absorption Spectra of Planarian Visual Pigments and Two States of the Metarhodopsin Intermediates. Photochem Photobiol 1999. [DOI: 10.1111/j.1751-1097.1999.tb05312.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Affiliation(s)
- C. Vreys
- Zoology Research Group, Limburgs Universitair Centrum, B‐3590 Diepenbeek, Belgium
| | - N. K. Michiels
- Max‐Planck‐Institut für Verhaltensphysiologie, PO Box 1564, D–82305 Seewiesen (Starnberg), Germany
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Katsu A, Yoshiji O, Kazumi A, Naohiko I. Electrical responses and K+ activity changes to light in the ocellus of the planarian Dugesia japonica. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0300-9629(94)90198-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Ozaki K, Hara R, Hara T. Histochemical localization of retinochrome and rhodopsin studied by fluorescence microscopy. Cell Tissue Res 1983; 233:335-45. [PMID: 6616571 DOI: 10.1007/bf00238300] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Retinochrome is readily reduced by sodium borohydride into an N-retinyl protein that emits visible fluorescence upon irradiation with near-ultraviolet light. Rhodopsin is also converted to a similar fluorescent product, but only when denatured with formaldehyde before reduction. Based upon this difference, retinochrome was discriminated from rhodopsin on frozen sections. The distribution of these two photopigments in various photosensitive tissues was examined by means of epifluorescence microscopy. In the octopus retina (Octopus vulgaris), the yellow-green fluorescence of reduced retinochrome was observed in both the basal regions of the outer segments and throughout the inner segments of the visual cells, while the fluorescence of reduced rhodopsin was restricted to within the rhabdomal layer of the outer segments. In the squid parolfactory vesicles (Todarodes pacificus), rhodopsin was present in the central lumen, which contains the distal processes of the photoreceptor cells, while retinochrome was detected in the myeloid bodies scattered within the vesicular wall. In the slug retina (Limax flavus), rhodopsin was found in the microvilli, and retinochrome appeared to be concentrated in the photic vesicles of the visual cells.
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Spectral Sensitivity and Color Vision in Invertebrates. COMPARATIVE PHYSIOLOGY AND EVOLUTION OF VISION IN INVERTEBRATES 1979. [DOI: 10.1007/978-3-642-66999-6_9] [Citation(s) in RCA: 104] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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