The electrical light response of theLimulus ventral nerve photoreceptor, a superposition of distinct components ? Observable by variation of the state of light adaptation

1981 ◽  
Vol 141 (3) ◽  
pp. 303-310 ◽  
Author(s):  
G�nther Maaz ◽  
Karoly Nagy ◽  
Hennig Stieve ◽  
Josef Klomfa�
Keyword(s):  
Light Adaptation ◽  
Light Response ◽  
The State ◽  
Ventral Nerve Photoreceptor

The Sensitivity Shift Due to Light Adaptation Depending on the Extracellular Calcium Ion Concentration in Limulus Ventral Nerve Photoreceptor

1984 ◽  
Vol 39 (6) ◽  
pp. 662-679 ◽  
Author(s):  
H. Stieve ◽  
M. Bruns ◽  
H. Gaube
Keyword(s):  
Calcium Ion ◽  
Light Adaptation ◽  
Light Response ◽  
Ion Concentration ◽  
Ion Concentrations ◽  
Intracellular Ca ◽  
Calcium Effect ◽  
Calcium Ion Concentration ◽  
Additional Reduction ◽  
Ventral Nerve Photoreceptor

Receptor potentials of Limulus ventral photoreceptors were recorded in two defined states of moderate light- and considerable dark adaptation (LA, DA) by a repeated stimulus sequence consisting of a conditioning 2 s illumination (white light, response saturating intensity) followed by two 10 ms test flashes at fixed intervals evoking LA and DA responses (intensity varied from threshold to saturation of response amplitude). The half saturating intensity I50 was determined from response height vs log stimulus intensity curves for LA and DA, while the photoreceptor was superfused either by reference saline (physiological ion concentrations, including 10 mmol/l Ca2+) or by test salines in which the [Ca2+] was varied between 40 μmol/l and 100 mmol/l. The sensitivity of the dark-adapted receptor does not significantly depend on the [Ca2+]ex, but the sensitivity shift due to LA (measured by /50) is reduced when the [Ca2+]ex is lowered, and augmented when the [Ca2+]ex is increased. Additional reduction of the [Na2+]ex from 463 mmol/l to 46 mmol/l or increase of the [Mg2+]ex from 50 mmol/l to 100 mmol/l does not counteract the effect of lowered [Ca2+]ex on LA. The results confirm the assumption that a transient increase of the intracellular [Ca2+] supplied from extracellular sources during the light response is the main cause for LA This calcium effect on light adaptation is neither characterized by a calcium/sodium antagonism, nor mimicked by magnesium, in contrast to the calcium effect on the gating of the light-activated ion channels.

The Sensitivity of the Ventral Nerve Photoreceptor of Limulus Recovers after Light Adaptation in Two Phases of Dark Adaptation

1986 ◽  
Vol 41 (5-6) ◽  
pp. 657-667 ◽  
Author(s):  
I. Claßen-Linke ◽  
H. Stieve
Keyword(s):  
Dark Adaptation ◽  
Time Course ◽  
Light Adaptation ◽  
Light Flash ◽  
Light Response ◽  
Receptor Potential ◽  
Second Phase ◽  
Two Phases ◽  
Ventral Nerve Photoreceptor ◽  
External Calcium

The time course of the recovery of the sensitivity of the Limulus ventral nerve photoreceptor was measured during dark adaptation following light adaptation by a bright 1 or 5 s illumination. The stimulus intensity ICR of a 300 μs light flash evoking a response of criterion amplitude (receptor potential or receptor current under voltage clamp conditions) was used as measure of sensitivity.The time course of dark adaptation shows two phases with time constants in the range of 5-9 s and 300-500 s (15 °C). Only the first of the two phases is significantly changed when the extracel- lular Ca2+-concentration is varied.The power function ICR = a·Io-tDA-b gives a good data fit for each of the two phases of dark adaptation. In the first phase the factor ax and the exponent bx are decreased when the external calcium is lowered from 10 mmol/1 to 250 μmol/1. Conversely a1 and b1 are increased when the Ca2+-concentration is raised to 40 mmol/1. For the second phase neither a2 nor b2 is changed significantly upon the changes in calcium concentration in the same experiments.The two phases of dark adaptation reflect the behaviour of the two components C1 and C2 of the electrical light response (receptor potential or receptor current). Under the conditions described here C, determines the size of the light response during the first phase of dark adaptation whereas C2 mainly influences the size of the response during the second phase.Interpretation: The fast first phase of dark adaptation is determined by the change in intracellu- lar Ca2+-concentration. The slower second phase of dark adaptation is not primarily calcium- controlled.

The influence of extracellular calcium ions on the light response of Limulus ventral nerve photoreceptor

1979 ◽  
Vol 19 (4) ◽  
pp. 351
Author(s):  
M. Bruns ◽  
M. Giesen ◽  
G. Maaz ◽  
M. Pflaum ◽  
H. Stieve
Keyword(s):  
Calcium Ions ◽  
Light Response ◽  
Extracellular Calcium ◽  
Ventral Nerve Photoreceptor

scholarly journals Optically Modulated Resistance Switching Polarities in BaTiO3 Thin Film

2020 ◽  
Author(s):  
Jing Wang ◽  
Bailey Bedford ◽  
Chanle Chen ◽  
Ludi Miao ◽  
Binghcheng Luo
Keyword(s):  
Thin Film ◽  
Oxygen Vacancy ◽  
Excitation Energy ◽  
Ultraviolet Light ◽  
Light Response ◽  
Resistance Switching ◽  
The State ◽  
Switching Behavior ◽  
Memory Devices ◽  
Resistive Memory

The light response and resistance switching behavior in BaTiO3 (BTO) films are studied for a symmetric Pt/BTO/Pt structure. The resistance of films as a function of time with and without ultraviolet light has been studied. Furthermore, resistance switching behavior was clearly observed based on the application of 365 nm wavelength ultraviolet light. Consequently, the polarities of resistance switching can be controlled by ultraviolet light when the energy is larger than the band excitation energy. It is proposed that the polarity of the resistance switching is dictated by the competition of the ferroelectricity and oxygen vacancy migration. This provides a new mechanism for modulating the state of ferroelectric resistive memory devices.

Changes of Acuity during Light and Dark Adaptation in the Dragonfly Compound Eye

1990 ◽  
Vol 45 (1-2) ◽  
pp. 137-142 ◽  
Author(s):  
Eric J. Warrant ◽  
Robert B. Pinter
Keyword(s):  
Dark Adaptation ◽  
Time Course ◽  
Light Adaptation ◽  
Compound Eye ◽  
Sensitivity Function ◽  
The State ◽  
Intracellular Recordings ◽  
Acceptance Angle ◽  
Angular Sensitivity ◽  
Rapid Reduction

Abstract Intracellular recordings of angular sensitivity from the photoreceptors of Aeschnid dragonflies (Hemianax papuensis and Aeschna brevistyla) are used to determine the magnitude and time course of acuity changes following alterations of the state of light or dark adaptation. Acuity is defined on the basis of the acceptance angle, Δρ (the half-width of the angular-sensitivity function). The maximally light-adapted value of Δρ is half the dark-adapted value, indicating greater acuity during light adaptation. Following a change from light to dark adaptation, Δρ increases slowly, requiring at least 3 min to reach its dark-adapted value. In contrast, the reverse change (dark to light) induces a rapid reduction of Δρ , and at maximal adapting luminances, this reduction takes place in less than 10 sec.

scholarly journals Photopigment quenching is Ca2+ dependent and controls response duration in salamander L-cone photoreceptors

2010 ◽  
Vol 135 (4) ◽  
pp. 355-366 ◽  
Author(s):  
Hugh R. Matthews ◽  
Alapakkam P. Sampath
Keyword(s):  
Time Constant ◽  
Light Adaptation ◽  
Light Response ◽  
Response Duration ◽  
Photoreceptor Cells ◽  
Quenching Rate ◽  
Vertebrate Photoreceptor ◽  
Cone Response ◽  
Rate Limiting ◽  
Phototransduction Cascade

The time scale of the photoresponse in photoreceptor cells is set by the slowest of the steps that quench the light-induced activity of the phototransduction cascade. In vertebrate photoreceptor cells, this rate-limiting reaction is thought to be either shutoff of catalytic activity in the photopigment or shutoff of the pigment's effector, the transducin-GTP–phosphodiesterase complex. In suction pipette recordings from isolated salamander L-cones, we found that preventing changes in internal [Ca2+] delayed the recovery of the light response and prolonged the dominant time constant for recovery. Evidence that the Ca2+-sensitive step involved the pigment itself was provided by the observation that removal of Cl− from the pigment's anion-binding site accelerated the dominant time constant for response recovery. Collectively, these observations indicate that in L-cones, unlike amphibian rods where the dominant time constant is insensitive to [Ca2+], pigment quenching rate limits recovery and provides an additional mechanism for modulating the cone response during light adaptation.

scholarly journals Regulation of cGMP levels by guanylate cyclase in truncated frog rod outer segments.

1989 ◽  
Vol 94 (4) ◽  
pp. 649-668 ◽  
Author(s):  
S Kawamura ◽  
M Murakami
Keyword(s):  
Guanylate Cyclase ◽  
Outer Segment ◽  
Time Course ◽  
Light Adaptation ◽  
Light Response ◽  
Regulation Mechanism ◽  
Maximal Effect ◽  
Rod Outer Segment ◽  
Light Flashes ◽  
Dependent Mechanism

Cyclic GMP is the second messenger in phototransduction and regulates the photoreceptor current. In the present work, we tried to understand the regulation mechanism of cytoplasmic cGMP levels in frog photoreceptors by measuring the photoreceptor current using a truncated rod outer segment (tROS) preparation. Since exogenously applied substance diffuses into tROS from the truncated end, we could examine the biochemical reactions relating to the cGMP metabolism by manipulating the cytoplasmic chemical condition. In tROS, exogenously applied GTP produced a dark current whose amplitude was half-maximal at approximately 0.4 mM GTP. The conductance for this current was suppressed by light in a fashion similar to when it is activated by cGMP. In addition, no current was produced in the absence of Mg2+, which is known to be necessary for the guanylate cyclase activity. These results indicate that guanylate cyclase was present in tROS and synthesized cGMP from exogenously applied GTP. The enzyme activity was distributed throughout the rod outer segment. The amount of synthesized cGMP increased as the cytoplasmic Ca2+ concentration of tROS decreased, which indicated the activation of guanylate cyclase at low Ca2+ concentrations. Half-maximal effect of Ca2+ was observed at approximately 100 nM. tROS contained the proteins involved in the phototransduction mechanism and therefore, we could examine the regulation of the light response waveform by Ca2+. At low Ca2+ concentrations, the time course of the light response was speeded up probably because cGMP recovery was facilitated by activation of the cyclase. Then, if the cytoplasmic Ca2+ concentration of a photoreceptor decreases during light stimulation, the Ca2+ decrease may explain the acceleration of the light response during light adaptation. In tROS, however, we did observe an acceleration during repetitive light flashes when the cytoplasmic Ca2+ concentration increased during the stimulation. This result suggests the presence of an additional light-dependent mechanism that is responsible for the acceleration of the light response during light adaptation.

scholarly journals Light Adaptation in the Ventral Photoreceptor of Limulus

1974 ◽  
Vol 64 (2) ◽  
pp. 166-185 ◽  
Author(s):  
Richard Srebro ◽  
Michael Behbehani
Keyword(s):  
Time Course ◽  
Light Adaptation ◽  
Light Response ◽  
Slow Phase ◽  
Rapid Phase ◽  
Short Delay ◽  
Light Intensities ◽  
Lateral Eye ◽  
Complex Process ◽  
Two Phases

Light adaptation in both the ventral photoreceptor and the lateral eye photoreceptor is a complex process consisting of at least two phases. One phase, which we call the rapid phase of adaptation, occurs whenever there is temporal overlap of the discrete waves that compose a light response. The recovery from the rapid phase of adaptation follows an exponential time-course with a time constant of approximately 75 ms at 21°C. The rapid phase of adaptation occurs at light intensities barely above discrete wave threshold as well as at substantially higher light intensities with the same recovery time-course at all intensities. It occurs in voltage-clamped and unclamped photoreceptors. The kinetics of the rapid phase of adaptation is closely correlated to the photocurrent which appears to initiate it after a short delay. The rapid phase of adaptation is probably identical to what is called the "adapting bump" process. At light intensities greater than about 10 times discrete wave threshold another phase of light adaptation occurs. It develops slowly over a period of ½ s or so, and decays even more slowly over a period of several seconds. It is graded with light intensity and occurs in both voltage-clamped and unclamped photoreceptors. We call this the slow phase of light adaptation.

scholarly journals Isolation and Characterization of Drosophila retinal degeneration B Suppressors

Genetics ◽  
1999 ◽  
Vol 151 (2) ◽  
pp. 713-724 ◽  
Author(s):  
Don W Paetkau ◽  
Vecheslav A Elagin ◽  
Lisa M Sendi ◽  
David R Hyde
Keyword(s):  
Retinal Degeneration ◽  
Light Adaptation ◽  
Photoreceptor Cell ◽  
Light Response ◽  
Visual Transduction ◽  
Transfer Protein ◽  
Isolation And Characterization ◽  
Phosphatidylinositol Transfer ◽  
Normal Light

Abstract The Drosophila retinal degeneration B protein (RdgB) is a novel integral membrane phosphatidylinositol transfer protein required for photoreceptor cell viability and light response. We isolated one intragenic suppressor (rdgBsu100) and four autosomal suppressors of the hypomorphic rdgBKS222 retinal degeneration phenotype. The rdgBsu100 suppressor dramatically slowed rdgBKS222's photoreceptor degeneration without significantly improving the electroretinogram (ERG) light response. One autosomal recessive suppressor [su(rdgB)69] significantly slowed rdgBKS222 retinal degeneration and restored the ERG light response near to that of the wild type. Unlike all the previously characterized rdgB suppressors, the four new autosomal suppressors do not affect the ERG light response in rdgB+ flies. Only Su(rdgB)116 exhibited a mutant phenotype in a rdgB+ background, which was smaller R1-6 rhabdomeres. We also examined the extent to which two previously identified visual transduction mutations suppressed rdgB retinal degeneration. Absence of one of the light-activated calcium channels (trpCM) slowed the onset of rdgB-dependent degeneration. However, loss of protein kinase C (inaC209), which blocks photoreceptor cell deactivation, desensitization, and light adaptation, failed to suppress rdgB degeneration under normal light conditions. This demonstrates that TRP activity, but not INAC, is required for rapid rdgB-dependent degeneration.

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