Spectral sensitivity of intracellular responses from visual cells in median ocellus of Limulus polyphemus

The spectral sensitivities of single Limulus median ocellus photoreceptors have been determined from records of receptor potentials obtained using intracellular microelectrodes. One class of receptors, called UV cells (ultraviolet cells), depolarizes to near-UV light and is maximally sensitive at 360 nm; a Dartnall template fits the spectral sensitivity curve. A second class of receptors, called visible cells, depolarizes to visible light; the spectral sensitivity curve is fit by a Dartnall template with λmax at 530 nm. Dark-adapted UV cells are about 2 log units more sensitive than dark-adapted visible cells. UV cells respond with a small hyperpolarization to visible light and the spectral sensitivity curve for this hyperpolarization peaks at 525–550 nm. Visible cells respond with a small hyperpolarization to UV light, and the spectral sensitivity curve for this response peaks at 350–375 nm. Rarely, a double-peaked (360 and 530 nm) spectral sensitivity curve is obtained; two photopigments are involved, as revealed by chromatic adaptation experiments. Thus there may be a small third class of receptor cells containing two photopigments.

Download Full-text

Spectral Sensitivity of Single Visual Cells

Nature ◽

10.1038/190639a0 ◽

1961 ◽

Vol 190 (4776) ◽

pp. 639-639 ◽

Cited By ~ 33

Author(s):

H. AUTRUM ◽

D. BURKHARDT

Keyword(s):

Spectral Sensitivity ◽

Visual Cells

Download Full-text

Electrophysiological measurements of spectral sensitivity of central visual cells in eye of blowfly

Nature ◽

10.1038/260342a0 ◽

1976 ◽

Vol 260 (5549) ◽

pp. 342-344 ◽

Cited By ~ 23

Author(s):

PETER MEFFERT ◽

ULRICH SMOLA

Keyword(s):

Spectral Sensitivity ◽

Visual Cells ◽

Electrophysiological Measurements

Download Full-text

Scotopic Spectral Sensitivity and the Absorbance of Visual Pigments in Isolated Visual Cells and in the Intact Retina

Xth I.S.C.E.R.G. Symposium - Documenta Ophthalmologica Proceedings Series ◽

10.1007/978-94-010-2697-0_29 ◽

1973 ◽

pp. 269-280

Author(s):

James K. Bowmaker

Keyword(s):

Spectral Sensitivity ◽

Visual Pigments ◽

Visual Cells

Download Full-text

Electroretinogram Characteristics and the Spectral Mechanisms of the Median Ocellus and the Lateral Eye in Limulus polyphemus

The Journal of General Physiology ◽

10.1085/jgp.50.9.2267 ◽

1967 ◽

Vol 50 (9) ◽

pp. 2267-2287 ◽

Cited By ~ 26

Author(s):

Robert M. Chapman ◽

Abner B. Lall

Keyword(s):

Spectral Sensitivity ◽

Visual Pigment ◽

Light Adaptation ◽

Compound Eye ◽

State Level ◽

Chromatic Adaptation ◽

Absorption Bands ◽

Energy Functions ◽

Lateral Eye ◽

Median Ocellus

Electrical responses (ERG) to light flashes of various wavelengths and energies were obtained from the dorsal median ocellus and lateral compound eye of Limulus under dark and chromatic light adaptation. Spectral mechanisms were studied by analyzing (a) response waveforms, e.g. response area, rise, and fall times as functions of amplitude, (b) slopes of amplitude-energy functions, and (c) spectral sensitivity functions obtained by the criterion amplitude method. The data for a single spectral mechanism in the lateral eye are (a) response waveforms independent of wavelength, (b) same slope for response-energy functions at all wavelengths, (c) a spectral sensitivity function with a single maximum near 520 mµ, and (d) spectral sensitivity invariance in chromatic adaptation experiments. The data for two spectral mechanisms in the median ocellus are (a) two waveform characteristics depending on wavelength, (b) slopes of response-energy functions steeper for short than for long wavelengths, (c) two spectral sensitivity peaks (360 and 530–535 mµ) when dark-adapted, and (d) selective depression of either spectral sensitivity peak by appropriate chromatic adaptation. The ocellus is 200–320 times more sensitive to UV than to visible light. Both UV and green spectral sensitivity curves agree with Dartnall's nomogram. The hypothesis is favored that the ocellus contains two visual pigments each in a different type of receptor, rather than (a) various absorption bands of a single visual pigment, (b) single visual pigment and a chromatic mask, or (c) fluorescence. With long duration light stimuli a steady-state level followed the transient peak in the ERG from both types of eyes.

Download Full-text

Central origin of the efferent neurons projecting to the eyes of Limulus polyphemus

Visual Neuroscience ◽

10.1017/s0952523800001334 ◽

1991 ◽

Vol 6 (5) ◽

pp. 481-495 ◽

Cited By ~ 23

Author(s):

B. G. Calman ◽

B.- A. Battelle

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Optic Nerve ◽

Optic Tract ◽

Limulus Polyphemus ◽

Cell Of Origin ◽

Optic Nerves ◽

Visual Cells ◽

Efferent Neurons ◽

The Central Nervous System

AbstractCircadian 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 μm. 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.

Download Full-text

Ultraviolet-Induced Sensitivity to Visible Light in Ultraviolet Receptors of Limulus

The Journal of General Physiology ◽

10.1085/jgp.59.2.186 ◽

1972 ◽

Vol 59 (2) ◽

pp. 186-200 ◽

Cited By ~ 50

Author(s):

John Nolte ◽

Joel E. Brown

Keyword(s):

Spectral Sensitivity ◽

Electrical Response ◽

Receptor Potential ◽

Ion Concentration ◽

Sensitivity Curve ◽

Long Wavelength ◽

Median Ocellus ◽

Wavelength Light ◽

Reversal Potentials ◽

Spectral Sensitivity Curve

In the UV-sensitive photoreceptors of the median ocellus (UV cells), prolonged depolarizing afterpotentials are seen following a bright UV stimulus. These afterpotentials are abolished by long-wavelength light. During a bright UV stimulus, long-wavelength light elicits a sustained negative-going response. These responses to long-wavelength light are called repolarizing responses. The spectral sensitivity curve for the repolarizing responses peaks at 480 nm; it is the only spectral sensitivity curve for a median ocellus electrical response known to peak at 480 nm. The reversal potentials of the repolarizing response and the depolarizing receptor potential are the same, and change in the same way when the external sodium ion concentration is reduced. We propose that the generation of repolarizing responses involves a thermally stable intermediate of the UV-sensitive photopigment of UV cells.

Download Full-text