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Nocturnal Myrmecia ants have faster temporal resolution at low light levels but lower adaptability compared to diurnal relatives. iScience 2022; 25:104134. [PMID: 35402879 PMCID: PMC8991095 DOI: 10.1016/j.isci.2022.104134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 02/10/2022] [Accepted: 03/17/2022] [Indexed: 11/21/2022] Open
Abstract
Nocturnal insects likely have evolved distinct physiological adaptations to enhance sensitivity for tasks, such as catching moving prey, where the signal-noise ratio of visual information is typically low. Using electroretinogram recordings, we measured the impulse response and the flicker fusion frequency (FFF) in six congeneric species of Myrmecia ants with different diurnal rhythms. The FFF, which measures the ability of an eye to respond to a flickering light, is significantly lower in nocturnal ants (∼125 Hz) compared to diurnal ants (∼189 Hz). However, the nocturnal ants have faster eyes at very low light intensities than the diurnal species. During the day, nocturnal ants had slower impulse responses than their diurnal counterparts. However, at night, both latency and duration significantly shortened in nocturnal species. The characteristics of the impulse responses varied substantially across all six species and did not correlate well with the measured flicker fusion frequency. Flicker fusion frequency is lower in nocturnal ants compared to diurnal ants Latency and duration of the impulse response shorten at night in nocturnal ants In ants, the FFF is not predicted by the measured impulse response characteristics
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Brodrick EA, How MJ, Hemmi JM. Fiddler crab electroretinograms reveal vast circadian shifts in visual sensitivity and temporal summation in dim light. J Exp Biol 2022; 225:274663. [PMID: 35156128 PMCID: PMC8976941 DOI: 10.1242/jeb.243693] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 02/04/2022] [Indexed: 11/20/2022]
Abstract
Many animals with compound eyes undergo major optical changes to adjust visual sensitivity from day to night, often under control of a circadian clock. In fiddler crabs, this presents most conspicuously in the huge volume increase of photopigment-packed rhabdoms and the widening of crystalline cone apertures at night. These changes are hypothesised to adjust the light flux to the photoreceptors and to alter optical sensitivity as the eye moves between light- and dark-adapted states. Here, we compare optical sensitivity in fiddler crab eyes (Gelasimus dampieri) during daytime and night via three electroretinogram (ERG) experiments performed on light- and dark-adapted crabs.
1) Light intensity required to elicit a threshold ERG response varied over six orders of magnitude, allowing more sensitive vision for discriminating small contrasts in dim light after dusk. During daytime, the eyes remained relatively insensitive, which would allow effective vision on bright mudflats, even after prolonged dark adaptation.
2) Flicker fusion frequency (FFF) experiments indicated that temporal summation is employed in dim light to increase light-gathering integration times and enhance visual sensitivity during both night and day.
3) ERG responses to flickering lights during 60 mins of dark adaptation increased at a faster rate and greater extent after sunset compared to daytime. However, even brief, dim and intermittent light exposure strongly disrupted dark-adaptation processes.
Together, these findings demonstrate effective light adaptation to optimise vision over the large range of light intensities that these animals experience.
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Affiliation(s)
| | - Martin J. How
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| | - Jan M. Hemmi
- School of Biological Sciences & UWA Oceans Institute, University of Western Australia, Perth, WA 6009, Australia
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3
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Charpentier CL, Cohen JH. Chemical cues from fish heighten visual sensitivity in larval crabs through changes in photoreceptor structure and function. ACTA ACUST UNITED AC 2016; 218:3381-90. [PMID: 26538174 DOI: 10.1242/jeb.125229] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Several predator avoidance strategies in zooplankton rely on the use of light to control vertical position in the water column. Although light is the primary cue for such photobehavior, predator chemical cues or kairomones increase swimming responses to light. We currently lack a mechanistic understanding for how zooplankton integrate visual and chemical cues to mediate phenotypic plasticity in defensive photobehavior. In marine systems, kairomones are thought to be amino sugar degradation products of fish body mucus. Here, we demonstrate that increasing concentrations of fish kairomones heightened sensitivity of light-mediated swimming behavior for two larval crab species (Rhithropanopeus harrisii and Hemigrapsus sanguineus). Consistent with these behavioral results, we report increased visual sensitivity at the retinal level in larval crab eyes directly following acute (1-3 h) kairomone exposure, as evidenced electrophysiologically from V-log I curves and morphologically from wider, shorter rhabdoms. The observed increases in visual sensitivity do not correspond with a decline in temporal resolution, because latency in electrophysiological responses actually increased after kairomone exposure. Collectively, these data suggest that phenotypic plasticity in larval crab photobehavior is achieved, at least in part, through rapid changes in photoreceptor structure and function.
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Affiliation(s)
- Corie L Charpentier
- School of Marine Science and Policy, College of Earth, Ocean and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA
| | - Jonathan H Cohen
- School of Marine Science and Policy, College of Earth, Ocean and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA
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4
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Volkov V. Discovering electrophysiology in photobiology: A brief overview of several photobiological processes with an emphasis on electrophysiology. Commun Integr Biol 2014; 7:e28423. [PMID: 25328636 PMCID: PMC4183612 DOI: 10.4161/cib.28423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 03/01/2014] [Accepted: 03/03/2014] [Indexed: 11/19/2022] Open
Abstract
The mini-review gives special attention to holistic approach and mechanisms of processes. The physical and chemical frames and background for visual perception and signaling are discussed. Perception of photons by retinal rod cells is described in more detail starting from photon absorption and culminating in ion currents. Dark noise and temperature-dependence of photocurrents in photoreceptor cells are analyzed. Perception of polarized light, its effects and informational importance are discussed based on underlying mechanisms and specialized morphological structures of biological organisms. Role of statistics of photons in photoreception is questioned. The review also pinpoints new and developing directions and raises questions for future research.
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Affiliation(s)
- Vadim Volkov
- Faculty of Life Sciences and Computing; London Metropolitan University; London, UK
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5
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Battelle BA. What the clock tells the eye: lessons from an ancient arthropod. Integr Comp Biol 2013; 53:144-53. [PMID: 23639718 DOI: 10.1093/icb/ict020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Circadian changes in visual sensitivity have been observed in a wide range of species, vertebrates, and invertebrates, but the processes impacted and the underlying mechanisms largely are unexplored. Among arthropods, effects of circadian signals on vision have been examined in most detail in the lateral compound eye (LE) of the American horseshoe crab, Limulus polyphemus, a chelicerate arthropod. As a consequence of processes influenced by a central circadian clock, Limulus can see at night nearly as well as they do during the day. The effects of the clock on horseshoe crab LE retinas are diverse and include changes in structure, gene expression, and rhabdom biochemistry. An examination of the known effects of circadian rhythms on LEs shows that the effects have three important outcomes: an increase in visual sensitivity at night, a rapid decrease in visual sensitivity at dawn, and maintenance of eyes in a relatively low state of sensitivity during the day, even in the dark. All three outcomes may be critically important for species' survival. Specific effects of circadian rhythms on vision will certainly vary with species and according to life styles. Studies of the circadian regulation of Limulus vision have revealed that these effects can be extremely diverse and profound and suggest that circadian clocks can play a critical role in the ability of animals to adapt to the dramatic daily changes in ambient illumination.
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Affiliation(s)
- B-A Battelle
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, University of Florida, St Augustine, FL 32080, USA.
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6
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Battelle BA, Kempler KE, Parker AK, Gaddie CD. Opsin1-2, G(q)α and arrestin levels at Limulus rhabdoms are controlled by diurnal light and a circadian clock. ACTA ACUST UNITED AC 2013; 216:1837-49. [PMID: 23393287 DOI: 10.1242/jeb.083519] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dark and light adaptation in photoreceptors involve multiple processes including those that change protein concentrations at photosensitive membranes. Light- and dark-adaptive changes in protein levels at rhabdoms have been described in detail in white-eyed Drosophila maintained under artificial light. Here we tested whether protein levels at rhabdoms change significantly in the highly pigmented lateral eyes of wild-caught Limulus polyphemus maintained in natural diurnal illumination and whether these changes are under circadian control. We found that rhabdomeral levels of opsins (Ops1-2), the G protein activated by rhodopsin (G(q)α) and arrestin change significantly from day to night and that nighttime levels of each protein at rhabdoms are significantly influenced by signals from the animal's central circadian clock. Clock input at night increases Ops1-2 and G(q)α and decreases arrestin levels at rhabdoms. Clock input is also required for a rapid decrease in rhabdomeral Ops1-2 beginning at sunrise. We found further that dark adaptation during the day and the night are not equivalent. During daytime dark adaptation, when clock input is silent, the increase of Ops1-2 at rhabdoms is small and G(q)α levels do not increase. However, increases in Ops1-2 and G(q)α at rhabdoms are enhanced during daytime dark adaptation by treatments that elevate cAMP in photoreceptors, suggesting that the clock influences dark-adaptive increases in Ops1-2 and G(q)α at Limulus rhabdoms by activating cAMP-dependent processes. The circadian regulation of Ops1-2 and G(q)α levels at rhabdoms probably has a dual role: to increase retinal sensitivity at night and to protect photoreceptors from light damage during the day.
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Affiliation(s)
- Barbara-Anne Battelle
- The Whitney Laboratory for Marine Bioscience, 9505 Ocean Shore Blvd, St Augustine, FL 32080-8610, USA.
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7
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Katti C, Kempler K, Porter ML, Legg A, Gonzalez R, Garcia-Rivera E, Dugger D, Battelle BA. Opsin co-expression in Limulus photoreceptors: differential regulation by light and a circadian clock. ACTA ACUST UNITED AC 2010; 213:2589-601. [PMID: 20639420 DOI: 10.1242/jeb.043869] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A long-standing concept in vision science has held that a single photoreceptor expresses a single type of opsin, the protein component of visual pigment. However, the number of examples in the literature of photoreceptors from vertebrates and invertebrates that break this rule is increasing. Here, we describe a newly discovered Limulus opsin, Limulus opsin5, which is significantly different from previously characterized Limulus opsins, opsins1 and 2. We show that opsin5 is co-expressed with opsins1 and 2 in Limulus lateral and ventral eye photoreceptors and provide the first evidence that the expression of co-expressed opsins can be differentially regulated. We show that the relative levels of opsin5 and opsin1 and 2 in the rhabdom change with a diurnal rhythm and that their relative levels are also influenced by the animal's central circadian clock. An analysis of the sequence of opsin5 suggests it is sensitive to visible light (400-700 nm) but that its spectral properties may be different from that of opsins1 and 2. Changes in the relative levels of these opsins may underlie some of the dramatic day-night changes in Limulus photoreceptor function and may produce a diurnal change in their spectral sensitivity.
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Affiliation(s)
- C Katti
- Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Boulevard, St Augustine, FL 32080, USA
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8
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Birge RR. The unusual pK(a) of the rhodopsin chromophore: Is this how nature minimizes photoreceptor noise? Biophys J 2010; 64:1371-2. [PMID: 19431891 DOI: 10.1016/s0006-3495(93)81501-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- R R Birge
- Department of Chemistry, Syracuse University, Syracuse, New York 13244 USA
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9
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Abstract
A visual pigment molecule in a retinal photoreceptor cell can be activated not only by absorption of a photon but also "spontaneously" by thermal energy. Current estimates of the activation energies for these two processes in vertebrate rod and cone pigments are on the order of 40-50 kcal/mol for activation by light and 20-25 kcal/mol for activation by heat, which has forced the conclusion that the two follow quite different molecular routes. It is shown here that the latter estimates, derived from the temperature dependence of the rate of pigment-initiated "dark events" in rods, depend on the unrealistic assumption that thermal activation of a complex molecule like rhodopsin (or even its 11-cis retinaldehyde chromophore) happens through a simple process, somewhat like the collision of gas molecules. When the internal energy present in the many vibrational modes of the molecule is taken into account, the thermal energy distribution of the molecules cannot be described by Boltzmann statistics, and conventional Arrhenius analysis gives incorrect estimates for the energy barrier. When the Boltzmann distribution is replaced by one derived by Hinshelwood for complex molecules with many vibrational modes, the same experimental data become consistent with thermal activation energies that are close to or even equal to the photoactivation energies. Thus activation by light and by heat may in fact follow the same molecular route, starting with 11-cis to all-trans isomerization of the chromophore in the native (resting) configuration of the opsin. Most importantly, the same model correctly predicts the empirical correlation between the wavelength of maximum absorbance and the rate of thermal activation in the whole set of visual pigments studied.
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Affiliation(s)
- Petri Ala-Laurila
- Laboratory of Biomedical Engineering, Helsinki University of Technology, Helsinki, Finland.
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Pieprzyk AR, Weiner WW, Chamberlain SC. Mechanisms controlling the sensitivity of the Limulus lateral eye in natural lighting. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2003; 189:643-53. [PMID: 12827424 DOI: 10.1007/s00359-003-0437-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2003] [Revised: 05/23/2003] [Accepted: 05/24/2003] [Indexed: 11/28/2022]
Abstract
Electroretinograms were recorded from the horseshoe crab compound eye using a high-intensity light-emitting diode and a whole-eye seawater electrode. Recordings were made from both lateral eyes in natural daylight or in continuous darkness with the optic nerve intact or cut. Recordings from two eyes of the same animal in different conditions facilitated direct comparisons of the effects of diurnal lighting and circadian efferent activity on the daily patterns of sensitivity of the eye. Structural changes appear to account for about half of the total electroretinogram excursion. Circadian input begins about 45 min in advance of sunset and the nighttime sensitivity returns to the daytime values 20 min after sunrise. When the optic nerve is cut, the nighttime sensitivity shows exponential decay over the next 5 or 6 days, consistent with a light-triggered structural light adaptation process unopposed by efferent input. Our results suggest that two mechanisms mediate the increase in lateral eye sensitivity at night-physiological dark adaptation and circadian efferent input. Three mechanisms appear to be involved in mediating the decrease in lateral eye sensitivity during daylight-physiological light adaptation, a continuous structural light adaptation process, and a separate light-triggered, efferent-primed structural light adaptation process.
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Affiliation(s)
- A R Pieprzyk
- Department of Bioengineering and Neuroscience, Institute for Sensory Research, Syracuse University, Syracuse, NY 13244-5290, USA
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11
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Abstract
Much is known about the anatomy of Limulus retinal efferent neurons and the structural and functional consequences of their activation. Retinal efferent axons arise from cell bodies located in the cheliceral ganglia of the brain, and they project out all of the optic nerves. Their unique neurosecretory-like terminals contact all cell types in lateral eye ommatidia, the retinular cells of the median eye, and the internal rhabdom of ventral photoreceptors. Lateral and median rudimentary photoreceptors are also innervated. The activity of the efferents is circadian. They are active during the subjective night and inactive during the subjective day. Activation of the efferents drives dramatic and diverse changes in the structure and function of Limulus eyes and causes the sensitivity and responsiveness of the eyes to light to increase at night. Relatively little is known about the molecular mechanisms that produce these structural and functional changes, but one efferent-activated biochemical cascade has been identified. The biogenic amine octopamine is released from efferent terminals, and an octopamine-stimulated rise in cAMP in photoreceptors, with a subsequent activation of cAMP-dependent protein kinase, mediates many of the known effects of efferent input. A photoreceptor-specific protein, myosin III, is phosphorylated in response to efferent input; this protein may play a role in the efferent stimulated changes in photoreceptor structure and function. Anatomical, biophysical, biochemical, and molecular approaches are now being effectively combined in studies of Limulus eyes; thus, this preparation should be particularly useful for further detailed investigations of mechanisms underlying the modulation of primary sensory cells by efferent input.
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Affiliation(s)
- Barbara-Anne Battelle
- Whitney Laboratory and Department of Neuroscience, University of Florida, St. Augustine, Florida 32080, USA.
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12
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Barlow R. Circadian and efferent modulation of visual sensitivity. PROGRESS IN BRAIN RESEARCH 2001; 131:487-503. [PMID: 11420965 DOI: 10.1016/s0079-6123(01)31039-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- R Barlow
- Center for Vision Research, Department of Ophthalmology, Upstate Medical University, 750 Adams Street, Syracuse, NY 13210, USA.
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13
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Barlow RB, Hitt JM, Dodge FA. Limulus vision in the marine environment. THE BIOLOGICAL BULLETIN 2001; 200:169-176. [PMID: 11341579 DOI: 10.2307/1543311] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Horseshoe crabs use vision to find mates. They can reliably detect objects resembling potential mates under a variety of lighting conditions. To understand how they achieve this remarkable performance, we constructed a cell based realistic model of the lateral eye to compute the ensembles of optic nerve activity ("neural images") it transmits to the brain. The neural images reveal a robust encocding of mate-like objects that move underwater during the day. The neural images are much less clear at night, even though the eyes undergo large circadian increases of sensitivity that nearly compensate for the millionfold decreasein underwater lighting after sundown. At night the neurral images are noisy, dominated by bursts of nerve impulses from random photon events that occur at low nighttime levels of illumination. Deciphering the eye's input to the brain begins at the first synaptic level with lowpass temporal and spatial filtering. Both neural filtering mechanisms improve the signal-to-noise properties of the eye's input, yielding clearer neural images of potential mates, especiallyat night. Insights about visual processing by the relatively simple visual system of Limulus may aid in the designof robotic sensors for the marine environment.
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Affiliation(s)
- R B Barlow
- Center for Vision Research, Department of Ophthalmology, Upstate Medical University, Syracuse, New York 13210, USA.
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14
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Chapter 8 Phototransduction mechanisms in microvillar and ciliary photoreceptors of invertebrates. HANDBOOK OF BIOLOGICAL PHYSICS 2000. [DOI: 10.1016/s1383-8121(00)80011-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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15
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Abstract
Phototransduction in Drosophila is mediated by a G-protein-coupled phospholipase C transduction cascade in which each absorbed photon generates a discrete electrical event, the quantum bump. In whole-cell voltage-clamp recordings, cAMP, as well as its nonhydrolyzable and membrane-permeant analogs 8-bromo-cAMP (8-Br-cAMP) and dibutyryl-cAMP, slowed down the macroscopic light response by increasing quantum bump latency, without changes in bump amplitude or duration. In contrast, cGMP or 8-Br-cGMP had no effect on light response amplitude or kinetics. None of the cyclic nucleotides activated any channels in the plasma membrane. The effects of cAMP were mimicked by application of the non-specific phosphodiesterase inhibitor IBMX and the adenylyl cyclase activator forskolin; zaprinast, a specific cGMP-phosphodiesterase inhibitor, was ineffective. Bump latency was also increased by targeted expression of either an activated G(s) alpha subunit, which increased endogenous adenylyl cyclase activity, or an activated catalytic protein kinase A (PKA) subunit. The action of IBMX was blocked by pretreatment with the PKA inhibitor H-89. The effects of cAMP were abolished in mutants of the ninaC gene, suggesting this nonconventional myosin as a possible target for PKA-mediated phosphorylation. Dopamine (10 microM) and octopamine (100 microM) mimicked the effects of cAMP. These results indicate the existence of a G-protein-coupled adenylyl cyclase pathway in Drosophila photoreceptors, which modulates the phospholipase C-based phototransduction cascade.
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16
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Chyb S, Hevers W, Forte M, Wolfgang WJ, Selinger Z, Hardie RC. Modulation of the light response by cAMP in Drosophila photoreceptors. J Neurosci 1999; 19:8799-807. [PMID: 10516299 PMCID: PMC6782748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Phototransduction in Drosophila is mediated by a G-protein-coupled phospholipase C transduction cascade in which each absorbed photon generates a discrete electrical event, the quantum bump. In whole-cell voltage-clamp recordings, cAMP, as well as its nonhydrolyzable and membrane-permeant analogs 8-bromo-cAMP (8-Br-cAMP) and dibutyryl-cAMP, slowed down the macroscopic light response by increasing quantum bump latency, without changes in bump amplitude or duration. In contrast, cGMP or 8-Br-cGMP had no effect on light response amplitude or kinetics. None of the cyclic nucleotides activated any channels in the plasma membrane. The effects of cAMP were mimicked by application of the non-specific phosphodiesterase inhibitor IBMX and the adenylyl cyclase activator forskolin; zaprinast, a specific cGMP-phosphodiesterase inhibitor, was ineffective. Bump latency was also increased by targeted expression of either an activated G(s) alpha subunit, which increased endogenous adenylyl cyclase activity, or an activated catalytic protein kinase A (PKA) subunit. The action of IBMX was blocked by pretreatment with the PKA inhibitor H-89. The effects of cAMP were abolished in mutants of the ninaC gene, suggesting this nonconventional myosin as a possible target for PKA-mediated phosphorylation. Dopamine (10 microM) and octopamine (100 microM) mimicked the effects of cAMP. These results indicate the existence of a G-protein-coupled adenylyl cyclase pathway in Drosophila photoreceptors, which modulates the phospholipase C-based phototransduction cascade.
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Affiliation(s)
- S Chyb
- Department of Anatomy, Cambridge University, Cambridge CB2 3DY, United Kingdom
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17
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Ruta VJ, Dodge FA, Barlow RB. Evaluation of Circadian Rhythms in the Limulus Eye. THE BIOLOGICAL BULLETIN 1999; 197:233-234. [PMID: 28281811 DOI: 10.2307/1542621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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18
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Abstract
The lateral eyes of the horseshoe crab Limulus polyphemus undergo dramatic daily changes in structure and function that lead to enhanced retinal sensitivity and responsiveness to light at night. These changes are controlled by a circadian neural input that alters photoreceptor and pigment cell shape, pigment migration, and phototransduction. Clock input to the eyes also regulates photomechanical movements within photoreceptors, including membrane shedding. The biochemical mechanisms underlying these diverse effects of the clock on the retina are unknown, but a major biochemical consequence of activating clock input to the eyes is a rise in the concentration of cAMP in photoreceptors and the phosphorylation of a 122 kDa visual system-specific protein. We have cloned and sequenced cDNA encoding the clock-regulated 122 kDa phosphoprotein and show here that it is a new member of the myosin III family. We report that Limulus myosin III is similar to other unconventional myosins in that it binds to calmodulin in the absence of Ca2+; it is novel in that it is phosphorylated within its myosin globular head, probably by cAMP-dependent protein kinase. The protein is present throughout the photoreceptor, including the region occupied by the photosensitive rhabdom. We propose that the phosphorylation of Limulus myosin III is involved in one or more of the structural and functional changes that occur in Limulus eyes in response to clock input.
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19
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Battelle BA, Andrews AW, Calman BG, Sellers JR, Greenberg RM, Smith WC. A myosin III from Limulus eyes is a clock-regulated phosphoprotein. J Neurosci 1998; 18:4548-59. [PMID: 9614231 PMCID: PMC6792693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The lateral eyes of the horseshoe crab Limulus polyphemus undergo dramatic daily changes in structure and function that lead to enhanced retinal sensitivity and responsiveness to light at night. These changes are controlled by a circadian neural input that alters photoreceptor and pigment cell shape, pigment migration, and phototransduction. Clock input to the eyes also regulates photomechanical movements within photoreceptors, including membrane shedding. The biochemical mechanisms underlying these diverse effects of the clock on the retina are unknown, but a major biochemical consequence of activating clock input to the eyes is a rise in the concentration of cAMP in photoreceptors and the phosphorylation of a 122 kDa visual system-specific protein. We have cloned and sequenced cDNA encoding the clock-regulated 122 kDa phosphoprotein and show here that it is a new member of the myosin III family. We report that Limulus myosin III is similar to other unconventional myosins in that it binds to calmodulin in the absence of Ca2+; it is novel in that it is phosphorylated within its myosin globular head, probably by cAMP-dependent protein kinase. The protein is present throughout the photoreceptor, including the region occupied by the photosensitive rhabdom. We propose that the phosphorylation of Limulus myosin III is involved in one or more of the structural and functional changes that occur in Limulus eyes in response to clock input.
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Affiliation(s)
- B A Battelle
- Whitney Laboratory and Department of Neuroscience, University of Florida, St. Augustine, Florida 32086, USA
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20
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Renninger GH, Farrell CA. Modulation of function in Limulus compound eye photoreceptors by octopamine enantiomers. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 1996. [DOI: 10.1016/1011-1344(96)07304-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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21
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Herzog ED, Powers MK, Barlow RB. Limulus vision in the ocean day and night: effects of image size and contrast. Vis Neurosci 1996; 13:31-41. [PMID: 8730987 DOI: 10.1017/s0952523800007100] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Male horseshoe crabs, Limulus polyphemus, use their eyes to locate mates day and night. We investigated their ability to detect targets of different size and contrast in a mating area of Buzzards Bay, Cape Cod, MA. We found that males can see large, high-contrast targets better than small, low-contrast ones. For targets of the same size, animals must be about 0.1 m closer to a low-contrast target to see it as well as a high-contrast one. For targets of the same contrast, animals must be approximately 0.2 m closer to a small target to see it as well as one twice as large. A decrease of 0.05 steradians in the size of the retinal image of a target can be compensated by a four-fold increase in contrast. About 60% of the animals detect black targets subtending 0.110 steradians (equivalent to an adult female viewed from about 0.56 m), while only 20% detect targets subtending 0.039 steradians. This study shows that horseshoe crabs maintain about constant contrast sensitivity under diurnal changes in light intensity in their natural environment. As a consequence of circadian and adaptive mechanisms in the retina, male horseshoe crabs can detect female-size objects about equally well day and night.
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Affiliation(s)
- E D Herzog
- Department of Bioengineering and Neuroscience, Syracuse University, USA
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22
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Birge RR, Barlow RB. On the molecular origins of thermal noise in vertebrate and invertebrate photoreceptors. Biophys Chem 1995; 55:115-26. [PMID: 7632872 DOI: 10.1016/0301-4622(94)00145-a] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Retinal photoreceptors generate discrete electrical events in the dark indistinguishable from those evoked by light and the resulting dark signals limit visual sensitivity at low levels of illumination. The random spontaneous events are strongly temperature dependent and in both vertebrate and invertebrate photoreceptors require activation energies usually in the range of 23 to 28 kcal mol-1. Recent molecular orbital studies and pH experiments on horseshoe crabs (Limulus) suggest that the thermal isomerization of a relatively unstable form of rhodopsin, one in which the Schiff-base linkage between the chromophore and protein is unprotonated, is responsible for thermal noise. This mechanism is examined in detail and compared to other literature models for photoreceptor noise. We conclude that this two-step process is likely to be the principal source of noise in all vertebrate and invertebrate photoreceptors. This model predicts that the rate of photoreceptor noise will scale in proportion to 10- xi, where xi is the pKa of the Schiff base proton on the retinyl chromophore. Nature minimizes photoreceptor noise by selecting a binding site geometry which shifts the pKa of the Schiff base proton to > 16, a value significantly larger than the pKa of the chromophore in bacteriorhodopsin (pKa approximately 13) or model protonated Schiff bases in solution (pKa approximately 7).
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Affiliation(s)
- R R Birge
- Department of Chemistry, Syracuse University, NY 13244, USA
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Zhang HJ, Jinks RN, Wishart AC, Battelle BA, Chamberlain SC, Fahrenbach WH, Kass L. An enzymatically enhanced recording technique for Limulus ventral photoreceptors: physiology, biochemistry, and morphology. Vis Neurosci 1994; 11:41-52. [PMID: 8011582 DOI: 10.1017/s0952523800011093] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Enzymatic treatments that facilitated whole-cell electrophysiological recordings were used on Limulus ventral photoreceptor cells. Ventral optic nerves were treated with either collagenase or collagenase, papain, and trypsin. Either treatment greatly increased the ease of making whole-cell recordings of transmembrane potentials. Light responses obtained from enzyme-treated photoreceptor cells were nearly identical to results obtained without enzyme treatment and compared favorably to in vivo recordings of light responses from the compound lateral eye. Enzyme-treated cells also responded to applied octopamine, as do untreated cells, with an increased phosphorylation of a 122-kD protein. This suggests that the external receptors and internal biochemical machinery required for at least one second-messenger cascade are present after enzyme treatment. The morphological integrity of enzyme-treated photoreceptor cells was examined with light microscopy as well as with scanning and transmission electron microscopy. In general, we found that each enzyme treatment greatly reduced the integrity of the layers of glial cells that surround the photoreceptor cells thereby making these cells easily accessible for whole-cell recordings of transmembrane potentials. The morphology of the rhabdomere was normal after enzymatic degradation of the adjacent glial covering.
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Affiliation(s)
- H J Zhang
- Department of Zoology, University of Maine, Orono 04469
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24
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Abstract
Retinal photoreceptors are noisy. They generate discrete electrical events in the dark indistinguishable from those evoked by light and thereby limit visual sensitivity at low levels of illumination. The random spontaneous events are strongly temperature-dependent and have been attributed to thermal isomerizations of the vitamin A chromophore of rhodopsin, the light-sensitive molecule in photoreceptors. But thermal generation of dark events in both vertebrate and invertebrate photoreceptors requires activation energies in the range of 23 to 27 kcal mol-1, which are significantly less than the energy barrier of 45 kcal mol-1, for photoisomerization of the chromophore of native rhodopsin. We propose that photoreceptor noise results from the thermal isomerization of a relatively unstable form of rhodopsin, one in which the Schiff-base linkage between the chromophore and protein is unprotonated. This molecular mechanism is supported by both theoretical calculations of the properties of rhodopsin and experimental measurements of the properties of photoreceptor noise.
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Affiliation(s)
- R B Barlow
- Institute for Sensory Research, Syracuse University, New York 13244
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Hanna WJ, Johnson EC, Chaves D, Renninger GH. Photoreceptor cells dissociated from the compound lateral eye of the horseshoe crab, Limulus polyphemus, II: Function. Vis Neurosci 1993; 10:609-20. [PMID: 7687862 DOI: 10.1017/s0952523800005319] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A combination of enzymatic digestions and mechanical disruption was used to isolate photoreceptor cells from the compound lateral eye of the horseshoe crab, Limulus polyphemus. The cells were maintained in a culture medium and tested for function using whole-cell and cell-attached patch configurations of the gigaseal technique. The cells dissociated from the eye generated spontaneous voltage and current bumps in the dark, and depolarized in a graded fashion to increasing intensities of light over several decades, producing responses similar to those of cells in vivo. Currents evoked during voltage clamp were similar to those in ventral photoreceptor cells of Limulus, although transient currents in the dark- and light-activated currents were smaller in isolated lateral eye cells, perhaps because of the slow speed and spatial nonuniformity of the clamp in these large cells. In addition to isolated cells, dissociation of the compound eye produced small clusters of cells and isolated ommatidia which were also tested for function. Comparison of the electrical characteristics of isolated cells with those of cells in small clusters and in their ommatidial matrix suggests that the electrical junctions normally connecting photoreceptor cells within an ommatidium are functional in the latter groups, but not in isolated cells. Cell-attached patches of rhabdomeral membrane of isolated cells contained light-activated channels, resembling those observed in ventral photoreceptor cells, but no voltage-activated channels. Similar patches of arhabdomeral membrane contained voltage-activated channels, but no light-activated channels. We conclude that this preparation is suitable for studies of processes involved in generating the light response in invertebrate photoreceptor cells.
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Affiliation(s)
- W J Hanna
- Department of Physics, University of Guelph, Ontario, Canada
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26
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Jinks RN, Hanna WJ, Renninger GH, Chamberlain SC. Photoreceptor cells dissociated from the compound lateral eye of the horseshoe crab, Limulus polyphemus, I: Structure and ultrastructure. Vis Neurosci 1993; 10:597-607. [PMID: 8338799 DOI: 10.1017/s0952523800005307] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Isolated photoreceptors are desirable for whole-cell and patch-clamp studies of functional properties of visual processes that cannot be clearly analyzed when the photoreceptors are coupled. The retina of the compound lateral eye of the horseshoe crab, Limulus polyphemus, was dissociated into individual retinular cells using an enzyme pretreatment consisting of collagenase, papain, and trypsin, and a two-stage mechanical dissociation. These photoreceptors are functionally viable in an organ culture medium for up to 1 week and possess naked arhabdomeral and rhabdomeral segment membranes which are easily accessible for whole-cell recordings. A dissection technique was also developed whereby the retinal epidermis and neural plexus, as well as the second-order eccentric cells, could be separated from the ommatidia of the compound lateral eye in one simple step, providing viable isolated ommatidia attached to the cornea. The enzyme pretreatment used for dissociating the retina was then used to remove the individual ommatidia from the corneal cones. Hoffman modulation contrast microscopy was used to develop a reliable method for sorting and collecting viable isolated retinular cells for morphological and electrophysiological studies. Morphological analysis using light microscopy and scanning and transmission electron microscopy revealed that isolated retinular cells are morphologically nearly identical to retinular cells in situ. Isolated retinular cells possess a normal rhabdomere with no apparent loss of microvillar membrane as a result of the isolation process. Ommatidia can presently be isolated with up to six retinular cells possessing essentially normal structure and ultrastructure including thick rays of rhabdom. Isolated ommatidia possess naked A-segment membranes which are also well suited for whole-cell recording techniques.
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Affiliation(s)
- R N Jinks
- Institute for Sensory Research, Syracuse University, NY 13244-5290
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27
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Kass L, Barlow RB. A circadian clock in the Limulus brain transmits synchronous efferent signals to all eyes. Vis Neurosci 1992; 9:493-504. [PMID: 1450102 DOI: 10.1017/s0952523800011299] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A circadian clock in the brain of the horseshoe crab, Limulus polyphemus, has an important role in the function of the peripheral visual system. At night, the clock transmits neural activity to the lateral, ventral, and median eyes via efferent optic nerve fibers. The activity occurs in synchronous bursts (maximum rate of 2 bursts/s) with individual efferent fibers contributing a single spike in each burst. The circadian efferent activity originates in the protocerebrum. Lateral connections synchronize the efferent activity recorded from the two halves of the protocerebrum, suggesting the existence of bilateral circadian oscillators. Circadian efferent activity survives excision of the brain and isolation of the protocerebrum. We conclude that circadian clock and its complex neural circuitry are fundamental components of the Limulus visual system.
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Affiliation(s)
- L Kass
- Marine Biological Laboratory, Woods Hole, MA
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28
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Chen DM, Christianson JS, Sapp RJ, Stark WS. Visual receptor cycle in normal and period mutant Drosophila: microspectrophotometry, electrophysiology, and ultrastructural morphometry. Vis Neurosci 1992; 9:125-35. [PMID: 1504021 DOI: 10.1017/s0952523800009585] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Visual pigment, sensitivity, and rhabdomere size were measured throughout a 12-h light/12-h dark cycle in Drosophila. Visual pigment and sensitivity were measured during subsequent constant darkness [dark/dark (D/D)]. MSP (microspectrophotometry) and the ERG (electroretinogram) revealed a cycling of visual pigment and sensitivity, respectively. A visual pigment decrease of 40% was noted at 4 h after light onset that recovered 2-4 h later in white-eyed (otherwise wild-type, w per+) flies. The ERG sensitivity [in w per+ flies in light/dark (L/D)] decreased by 75% at 4 h after light onset, more than expected if mediated by visual pigment (MSP) changes alone. ERG sensitivity begins decreasing 8 h before light onset while decreases in visual pigment begin 2 h after light onset. These cycles continue in constant darkness (D/D), suggesting a circadian rhythm. White-eyed period (per) mutants show similar cycles of visual pigment level and sensitivity in L/D; per's alterations, if any on the D/D cycles were subtle. The cross-sectional areas of rhabdomeres in w per+ were measured using electron micrographic (EM) morphometry. Area changed little through the L/D cycle.
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Affiliation(s)
- D M Chen
- Division of Biological Sciences, University of Missouri-Columbia 65211
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29
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Abstract
A circadian clock modulates the structure and function of the lateral eyes of Limulus polyphemus, greatly increasing their sensitivity at night. During the mating season, male Limulus are visually attracted both day and night to females and objects that resemble females. This paper asks how well Limulus can see day and night, and whether the circadian changes in retinal sensitivity might influence the ability of these animals to find mates. We recorded the visual behavior of male and female horseshoe crabs in the vicinity of an object--a cement hemisphere (29.5 cm diameter) similar in size and shape to a female horseshoe crab--placed in a mating area near Mashnee Dike, Bourne, Massachusetts. Males oriented toward this target from an average distance of 0.94 m during the day and 0.88 m at night; and females appeared to avoid the target. We conclude that males can see potential mates at night almost as well as they can during the day. Apparently the circadian changes in the retina help compensate for the daily changes in illumination in the animal's normal environment. This study provides the first evidence for a role of visual circadian rhythms in an animal's natural behavior.
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Affiliation(s)
- M K Powers
- Department of Psychology, Vanderbilt University, Nashville
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Calman BG, Battelle BA. Central origin of the efferent neurons projecting to the eyes of Limulus polyphemus. Vis Neurosci 1991; 6:481-95. [PMID: 2069900 DOI: 10.1017/s0952523800001334] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Circadian rhythms affect the anatomy, physiology, and biochemistry of the visual cells in the eyes of the horseshoe crab (Limulus polyphemus). These rhythms are mediated by the activity of efferent neurons that project from the central nervous system to all of the eyes. In this study, the optic nerves of Limulus were backfilled with Neurobiotin revealing the location of efferent cell bodies and their projections through the central nervous system. We propose that this efferent system mediates the circadian changes in visual functions in Limulus. Whether these cells are the circadian pacemaker neurons is unknown. The cell bodies of the efferent neurons are ovoid and have a diameter of 40-80 microns. They lie within the cheliceral ganglion of the tritocerebrum, just posterior to the protocerebrum. This ganglion is on the lateral edge of the circumesophageal ring, near the middle of the dorsal-ventral axis of the ring. Each optic nerve contains axons from both ipsilateral and contralateral efferent cells, and some, possibly all, of them project bilaterally and to more than one type of optic nerve. The efferent axons form a tract that projects anteriorly from the cell bodies to the protocerebrum, and bifurcates just lateral to the protocerebral bridge. One branch crosses the midline and projects anteriorly to the optic tract and medulla on the side contralateral to the cell of origin; the other branch follows a symmetric pathway on the ipsilateral side. Small branches arising from the major efferent axons in the optic tract project through the ocellar ganglia to the median optic nerves. The efferent axons branch again in the medulla, and some of these branches innervate the ventral optic nerves. The major branches of the efferent axons continue through the lamina and enter the lateral optic nerve.
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Affiliation(s)
- B G Calman
- Whitney Laboratory, University of Florida, St. Augustine 32086
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31
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Herman KG. Light-stimulated rhabdom turnover in Limulus ventral photoreceptors maintained in vitro. J Comp Neurol 1991; 303:11-21. [PMID: 2005235 DOI: 10.1002/cne.903030103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The role of light in turnover of photosensitive membranes was studied in isolated photoreceptors maintained in vitro. Ventral photoreceptors of the horseshoe crab, Limulus polyphemus, were used since they have been the subjects of many in vitro physiological studies. This study shows that the two classes of ventral photoreceptors, the large and small photoreceptors (Herman: companion paper), differ in their morphological response to light. The rhabdom of small photoreceptors is remarkable for its regularity, independent of lighting condition. The photosensitive microvilli of the rhabdom of small photoreceptors are narrow and almost always tightly packed in a hexagonal arrangement. In contrast, the morphology of the rhabdom of the large ventral photoreceptors is different in the dark and in the light, and the rhabdom undergoes turnover during lighting transitions. When fully dark-adapted, the photosensitive microvilli of large photoreceptors are narrow and well organized, sometimes in a crystalline array. However, in the light-adapted state, the microvilli are much thicker and very irregular. The transitions between the dark and light-adapted states, examined at midday, are rapid. After 5 minutes light exposure, the microvilli are dilated at their bases and shed membranes are present in the cytoplasm. By 30 minutes after light onset, the appearance of the rhabdom of large photoreceptors is indistinguishable from fully light-adapted cells. The transition to the dark-adapted state is equally rapid. Even at 5 or 12 minutes after light offset, most microvilli are narrow and quite regular, and by 30 minutes, the rhabdom usually appears to be fully dark-adapted. These experiments show that both the synthetic and degradative phases of rhabdom renewal take place in isolated photoreceptors. No efferent neural activity is required to initiate turnover; rather, changes in illumination alone are sufficient to generate rhabdom turnover in large ventral photoreceptors in vitro.
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Affiliation(s)
- K G Herman
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
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Chapter 12 Regulation of retinal functions by octopaminergic efferent neurons in Limulus. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0278-4327(91)90017-v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Kaplan E, Barlow RB, Renninger G, Purpura K. Circadian rhythms in Limulus photoreceptors. II. Quantum bumps. J Gen Physiol 1990; 96:665-85. [PMID: 2230712 PMCID: PMC2229002 DOI: 10.1085/jgp.96.3.665] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The light response of the lateral eye of the horseshoe crab, Limulus polyphemus, increases at night, while the frequency of spontaneous discrete fluctuations of its photoreceptor membrane potential (quantum bumps) decreases. These changes are controlled by a circadian clock in the brain, which transmits activity to the eye via efferent optic nerve fibers (Barlow, R. B., S. J. Bolanski, and M. L Brachman. 1977. Science. 197:86-89). Here we report the results of experiments in which we recorded from single Limulus photoreceptors in vivo for several days and studied in detail changes in their physiological and membrane properties. We found that: (a) The shape of (voltage) quantum bumps changes with the time of day. At night, spontaneous bumps and bumps evoked by dim light are prolonged. The return of the membrane potential to its resting level is delayed, but the rise time of the bump is unaffected. On average, the area under a bump is 2.4 times greater at night than during the day. (b) The rate of spontaneous bumps decreases at night by roughly a factor of 3, but their amplitude distribution remains unchanged. (c) The resting potential and resistance of the photoreceptor membrane do not change with the time of day. (d) the relationship between injected current and impulse rate of the second order neuron, the eccentric cell, also remains unchanged with the time of day. Thus the efferent input from the brain to the retina modulates some of the membrane properties of photoreceptor cells. Our findings suggest that the efferent input acts on ionic channels in the membrane to increase the sensitivity of the photoreceptor to light.
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Affiliation(s)
- E Kaplan
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543
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Donner K, Firsov ML, Govardovskii VI. The frequency of isomerization-like 'dark' events in rhodopsin and porphyropsin rods of the bull-frog retina. J Physiol 1990; 428:673-92. [PMID: 2231428 PMCID: PMC1181669 DOI: 10.1113/jphysiol.1990.sp018234] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
1. The dark current and responses to dim flashes were recorded with the suction pipette technique from single rods in pieces of bull-frog retina taken from either the dorsal porphyropsin or the ventral rhodopsin field. 2. The composition of visual pigment in the rods was determined by microspectrophotometry. Rods from the dorsal pieces contained 70-88% porphyropsin523 mixed with rhodopsin502. The ventral rods contained almost pure rhodopsin, any possible admixture of porphyropsin being below the level of detectability (less than 5%). 3. In most cells, the responses to dim flashes were well fitted by a four-stage linear filter model, with no systematic differences in the response kinetics of porphyropsin and rhodopsin rods. The amplitude of saturated responses varied between 8 and 55 pA and that of responses to single isomerizations between 0.4 and 3.5 pA. 4. In porphyropsin rods, discrete events similar to the response to one photoisomerization were clearly seen in complete darkness. The dark current amplitude histogram was fitted by a convolution of the probability densities for the Gaussian continuous noise component and the averaged dim-flash response waveform. This allows estimation of the frequency and amplitude of discrete events and the standard deviation of the continuous component. The mean frequency of discrete dark events thus obtained from six porphyropsin cells was 0.057 rod-1 s-1 at 18 degrees C. 5. In rhodopsin rods, the dark current amplitude histogram appeared completely symmetrical, indicating that the frequency of discrete events must be lower than 0.005 rod-1 s-1 (except in one rod where it was 0.006 events rod-1 s-1). Per molecule of rhodopsin, the events are then at least 5 times rarer than reported for toad rhodopsin rods at the same temperature. 6. The low rate of isomerization-like 'dark' events in bull-frog rhodopsin rods shows, firstly, that results cannot be generalized across species even for rhodopsins which appear spectrally identical. Secondly, it suggests that these events need not (in an evolutionary sense) constitute an irreducible noise factor which must set the ultimate limit to the sensitivity of dark-adapted vision. 7. The difference between porphyropsin and rhodopsin rods shows that, given (presumably) the same opsin, the pigment utilizing retinal2 and absorbing maximally at longer wavelengths produces more noise. The signal/noise ratio attained in the photoreceptor may be an important factor in the natural selection of visual pigments.
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Affiliation(s)
- K Donner
- Sechenov Institute of Evolutionary Physiology and Biochemistry, USSR Academy of Sciences, Leningrad
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35
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Kier CK, Chamberlain SC. Dual controls for screening pigment movement in photoreceptors of the Limulus lateral eye: circadian efferent input and light. Vis Neurosci 1990; 4:237-55. [PMID: 2078504 DOI: 10.1017/s0952523800003382] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The radial and longitudinal distribution of retinular screening pigment in the lateral eye of the horseshoe crab Limulus polyphemus was quantified under a variety of experimental conditions. Pigment position was characterized by the center and width of the radial distribution at four levels in the ommatidium. Under diurnal lighting, intact animals show movement of pigment granules from the periphery of the retinular cell at night towards the junction of the arhabdomeral and rhabdomeral segments of the retinular cell in the day. In constant darkness, intact animals exhibit the same circadian rhythm in pigment migration. Animals with bilaterally cut optic nerves do not receive circadian efferent input from the brain and show little pigment movement in diurnal lighting. In all of these cases, pigment was either aggregated in a band just peripheral to the rays of the rhabdom or dispersed to the periphery of the retinular cell. When dark-adapted animals are exposed to a sudden large light increment, pigment moves inward between the rays of the rhabdom. During the day, this inward response begins immediately and reverses as the ommatidial aperture begins to close. At night, the onset of the inward movement is delayed, but then occurs more rapidly than during the day. No significant longitudinal movement of photoreceptor screening pigment was detected under any of these experimental conditions. Two opposing mechanisms control the movement of screening pigment in these cells. Release of neurotransmitters from the circadian efferents causes outward movement; large increments of light cause inward movement. In the absence of sudden changes in light intensity, circadian efferent input, not cyclic lighting, appears to be the major determinant of screening pigment position. A sudden and large increment of light triggers the rapid inward movement which appears to be a protective mechanism optimized for daytime performance.
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Affiliation(s)
- C K Kier
- Department of Bioengineering, Syracuse University, NY 13244-5290
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36
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Abstract
The sensitivity of the Limulus lateral eye exhibits a pronounced circadian rhythm. At night a circadian oscillator in the brain activates efferent fibers in the optic nerve, inducing multiple changes in the physiological and anatomical characteristics of retinal cells. These changes increase the sensitivity of the retina by about five orders of magnitude. We investigated whether this increase in retinal sensitivity is accompanied by changes in the ability of the retina to process temporal information. We measured the frequency transfer characteristic (FTC) of single receptors (ommatidia) by recording the response of their optic nerve fibers to sinusoidally modulated light. We first measured the FTC in the less sensitive daytime state and then after converting the retina to the more sensitive nighttime state by electrical stimulation of the efferent fibers. The activation of these fibers shifted the peak of the FTC to lower frequencies and reduced the slope of the low-frequency limb. These changes reduce the eye's ability to detect rapid changes in light intensity but enhance its ability to detect dim flashes of light. Apparently Limulus sacrifices temporal resolution for increased visual sensitivity at night.
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Affiliation(s)
- R Batra
- Institute for Sensory Research, Syracuse University, New York 13244
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37
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Yamashita S. Efferent optic nerve impulses in response to illumination of single eyes of orb weaving spiders. Vision Res 1990; 30:817-21. [PMID: 2385922 DOI: 10.1016/0042-6989(90)90050-u] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Efferent impulses in the optic nerves of the orb weaving spiders Argiope amoena and A. bruennichii in response to illumination of single eyes were examined. When light stimulation was given to the anterior median (AM) eye, the frequency of efferent optic nerve impulses increased transiently only after the offset of illumination. In contrast, when the light was given to the anterior lateral (AL), posterior median (PM) or posterior lateral (PL) eye, the frequency of efferent impulses increased transiently both after the onset and after the offset of illumination. It is suggested that the impulse generation after the onset of illumination is caused by a gradual decrease in magnitude of depolarizing photoreceptor potentials in the AL, PL and PM eyes.
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Affiliation(s)
- S Yamashita
- Biological Laboratory, Kyushu Institute of Design, Fukuoka, Japan
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Renninger GH, Schimmel R, Farrell CA. Octopamine modulates photoreceptor function in the Limulus lateral eye. Vis Neurosci 1989; 3:83-94. [PMID: 2487100 DOI: 10.1017/s0952523800004405] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Activity at night in efferent nerve fibers from a central circadian clock produces changes in photoreceptor function in the lateral compound eye of Limulus: the response to light is increased; membrane potential fluctuations (bumps) occurring in the dark are suppressed; and the duration of bumps occurring both in the dark and under dim illumination is increased (Barlow et al., 1977; Kaplan & Barlow, 1980; Barlow, 1983; Barlow et al., 1985). Efferent nerve terminals release octopamine when activated (Battelle et al., 1982; Battelle & Evans, 1984, 1986); exogenous octopamine in vitro produces some of the changes resulting from efferent nerve activity in vivo (Kass et al., 1988). We report here that the increase in both on-transient and steady-state response to light induced by octopamine in the lateral eye in vitro are concentration dependent with threshold at or below 100 nM, saturation at or above 100 microM, and half-maximal increase in the range 1-10 microM. Octopamine also reduces bump activity in the dark in a concentration-dependent way. Unlike the increase in light response, the dependence of this effect on octopamine concentration is extremely variable from specimen to specimen. The effects of exogenous octopamine on light response and bump activity can sometimes be reversed by removing octopamine from the medium bathing the in vitro preparation. Octopamine also increases bump duration, apparently in a concentration-dependent manner. We have not succeeded in reversing this increase in bump duration. The concentration dependence of changes in photoreceptor response described here agrees qualitatively with the dependence of cAMP levels on octopamine in Limulus photoreceptors (Kaupp et al., 1982), lending further support to the idea that cAMP acts as a second messenger in the circadian control of photoreceptor function. Our results also suggest that the changes induced in the transient and steady-state response to light by both efferent nerve activity and exogenous octopamine have a common origin, which may differ from that responsible for the modulation of bump activity.
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Affiliation(s)
- G H Renninger
- Department of Physics, University of Guelph, Ontario, Canada
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Stupfel M, Gourlet V, Perramon A, Lemercerre C. Ultradian and circadian CO2 emission variations in nocturnal and diurnal animals exposed to a light stimulus. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. A, COMPARATIVE PHYSIOLOGY 1989; 94:415-25. [PMID: 2574093 DOI: 10.1016/0300-9629(89)90115-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1. Carbon dioxide emission (VCO2) has been continuously recorded in three laboratory animal species (Sprague-Dawley rats, Japanese quail, Hartley guinea-pigs) which differ by their nocturnal and diurnal activities. A 100 lux stimulus has been delivered at various time intervals. 2. A regular alternation of 12, 3 or 1.5 hr light (L) and darkness (D) gives VCO2 circadian and ultradian rhythms of 24, 6 or 3 hr periods, respectively, in quail and rats. 3. Such circadian and ultradian LD rhythms are not induced in all guinea-pigs. 4. The amplitudes of the VCO2 responses are greatest at D----L when the animals have a maximum diurnal activity and at L----D when their maximum activity is nocturnal. 5. Interactions between circadian and ultradian rhythms are seen in all LD experiments, as well as in continuous light (LL) or continuous dark (DD). 6. No more well-marked or even inverted VCO2 responses to the light stimuli may occur after several days of exposure to these LD alternations.
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Affiliation(s)
- M Stupfel
- Environmental Nuisances Research Group, French National Institute of Health and Medical Research (INSERM), Le Vésinet, France
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Kass L, Pelletier JL, Renninger GH, Barlow RB. Efferent neurotransmission of circadian rhythms in Limulus lateral eye. II. Intracellular recordings in vitro. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1988; 164:95-105. [PMID: 2466993 DOI: 10.1007/bf00612723] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We investigated efferent neurotransmission in the Limulus lateral eye by studying the action of pharmacological agents on responses of photoreceptor cells in vitro. We recorded transmembrane potentials from single cells in slices of retina that were excised during the day and maintained for several days in a culture medium. Potentials recorded in the absence of pharmacological agents resemble those recorded from cells in vivo during the day. Octopamine, a putative efferent neurotransmitter, induced changes in photoreceptor potentials that mimicked in part those generated at night by a circadian clock located in the brain. Specifically, octopamine (100 to 500 microM) decreased the frequency of occurrence of quantum bumps in the dark and increased the amplitude of photoreceptor responses to intermediate and high light intensities. Similar actions were produced by naphazoline (25 to 100 microM, potent agonist of octopamine), forskolin (8 to 400 microM, activator of adenylate cyclase), IBMX (1 mM, inhibitor of phosphodiesterase), and 8-bromo-cAMP (500 microM, analogue of cAMP). 8-bromo-cGMP (500 microM, analogue of cGMP) decreased the rate of spontaneous quantum bumps only. Our results support the hypothesis that (1) octopamine is an efferent neurotransmitter of circadian rhythms in the Limulus eye and that (2) it activates adenylate cyclase to increase levels of the second messenger, cAMP, in photoreceptor cells. Circadian changes in photoreceptor responses to moderate intensities may be a specific action of cAMP, since cGMP has no effect. Circadian changes in the rate of spontaneous quantum bumps may involve a less specific intermediate, since both cAMP and cGMP reduce bump rate. Characteristics of the retinal slice preparation precluded a detailed study of the effects of pharmacological agents on retinal morphology.
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Affiliation(s)
- L Kass
- Department of Zoology, University of Maine, Orono 04469
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Barash S, Suss E, Stavenga DG, Rubinstein CT, Selinger Z, Minke B. Light reduces the excitation efficiency in the nss mutant of the sheep blowfly Lucilia. J Gen Physiol 1988; 92:307-30. [PMID: 3225552 PMCID: PMC2228904 DOI: 10.1085/jgp.92.3.307] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The nss (no steady state) phototransduction mutant of the sheep blowfly Lucilia was studied electrophysiologically using intracellular recordings. The effects of the nss mutation on the receptor potential are manifested in the following features of the light response. (a) The responses to a flash or to dim lights are close to normal, but the receptor potential decays close to the baseline level during prolonged illumination after a critical level of light intensity is reached. (b) The decline of the response is accompanied by a large reduction in responsiveness to light that recovers within 20 s in the dark. (c) The full reduction in responsiveness to light is reached when approximately 13% of the photopigment molecules are converted from rhodopsin (R) to metarhodopsin (M). (d) A maximal net pigment conversion from R to M by blue light induces persistent inactivation in the dark, without an apparent voltage response. This inactivation could be abolished at any time by M-to-R conversion with orange light. The above features of the mutant indicate that the effect of the nss mutation on the light response of Lucilia is very similar to the effects of the transient receptor potential (trp) mutation on the photoreceptor potential of Drosophila. Noise analysis and voltage measurements indicate that the decay of the receptor potential is due to a severe reduction in the rate of occurrence of the elementary voltage responses (bumps). The bumps are only slightly modified in shape and amplitude during the decline of the response to light of medium intensity. There is also a large increase in response latency during intense background illumination. These results are consistent with the hypothesis that separate, independent mechanisms determine bump triggering and bump shape and amplitude. The nss mutation affects the triggering mechanism of the bump.
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Affiliation(s)
- S Barash
- Department of Physiology, Hadassah Medical School, Hebrew University, Jerusalem, Israel
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Abstract
Efferent fibers from a central circadian clock innervate photoreceptors along the ventral nerve of Limulus and release octopamine when active. We have recorded ERG-like responses from the ventral eye in vivo over several day periods. We have also used intracellular microelectrodes to study changes in ventral photoreceptor function during exogenous applications of octopamine (the putative efferent neurotransmitter), IBMX (a phosphodiesterase inhibitor), and forskolin (an adenylate cyclase activator): (1) Responses to light measured at night from ventral photoreceptors in vivo are greater in amplitude than those recorded during the day; (2) Octopamine and agents that increase intracellular levels of cAMP in ventral photoreceptors decrease the rate of spontaneous (dark) bumps, increase photoreceptor response to light without changing threshold, and often increase the bump duration; and (3) These changes in function of ventral photoreceptors are similar to those that have been observed in the photoreceptor of the lateral eye during circadian clock activity at night, and in vitro in the presence of those same pharmacological agents.
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Affiliation(s)
- L Kass
- Department of Zoology, University of Maine, Orono 04469
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Renninger GH, Kass L, Pelletier JL, Schimmel R. The eccentric cell of theLimulus lateral eye: encoder of circadian changes in visual responses. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1988. [DOI: 10.1007/bf00612435] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Horne JA, Renninger GH. Circadian photoreceptor organs inLimulus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1988. [DOI: 10.1007/bf01342709] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kass L, Berent MD. Circadian rhythms in adaptation to light of Limulus photoreception. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C, COMPARATIVE PHARMACOLOGY AND TOXICOLOGY 1988; 91:229-39. [PMID: 2905224 DOI: 10.1016/0742-8413(88)90190-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
1. The lateral eye of Limulus responds differently to light-adaptation depending upon whether the eye is tested during the day, or at night when a central circadian clock is known to activate efferent fibers that terminate in the retina. 2. At night, the decrement in retinal sensitivity due to light-adaptation is less pronounced immediately following a light-flash but is greater at longer times after the flash when compared with responses recorded during the day. 3. In our quantitative description of dark adaptation we find that at least two time constants are needed to describe the time course, and that the two decaying exponentials are differentially altered by circadian clock action. 4. We relate these day-to-night alterations in light-adaptive properties to circadian changes in physiology and morphology studied previously in Limulus photoreceptors.
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Affiliation(s)
- L Kass
- Department of Zoology, University of Maine, Orono 04469
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