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At least 1,711 records · Page 95Linked to original sources
PubMed1961

Eyestalk movements induced by polarized light in the ghost crab, Ocypode quadrata.

Differential visual sensitivity to vertical and horizontal linear polarization is shown in the light-induced eyestalk deviations of Ocypode quadrata. Responses with the e-vector vertical averaged about 6 degrees greater than those with e-vector horizontal. This difference approximates the relative eyestalk deviation induced by unpolarized light intensities having a ratio of 3:1

Animals↗
PubMed1963

SEPARATION OF TRANSDUCER AND IMPULSE-GENERATING PROCESSES IN SENSORY RECEPTORS.

New evidence is presented that spike and transducer processes in sensory receptors are independent events; impulse activity in tile crustacean stretch receptor neuron and the mammalian pacinian corpuscle was selectively blocked by a compound (tetrodotoxin) without affecting any of the parameters of the generator potential.

Animals↗
PubMed1964

CONTRACTION-BAND FORMATION IN BARNACLE MYOFIBRILS.

Contractions induced by adenosine triphosphate, in myofibrils isolated from the barnacle, Balanus aquilia, were observed with a phase microscope. The formation of contraction bands was well under way before the A-band came into contact with the Z-membrane. This is in disagreement with the hypothesis that contraction bands are formed when the A-band pushes against the Z-membrane.

Adenosine Triphosphate↗
PubMed1964

POLYMER SIMILAR TO POLYDEOXYADENYLATE-THYMIDYLATE IN VARIOUS TISSUES OF A MARINE CRAB.

Several species of a genus Cancer have a DNA that has a light buoyant density and that contains mainly deoxyadenylate and thymidylate. The presence of this polymer was demonstrated previously in testes and vas deferens. By a modified procedure for isolating DNA, the muscles, liver, and eggs of Cancer borealis are also shown to contain the deoxyadenylate-thymidylate-like polymer.

Adenine Nucleotides↗
PubMed1964

N-ETHYLMALEIMIDE INHIBITION OF HORSESHOE CRAB HEMOCYTE AGGLUTINATION.

The sulfhydryl inhibitor N-ethylmaleimide (NEM) inhibits the agglutination of horseshoe crab hemocytes. The inhibitory action is neutralized by adding cysteine to the NEM before it is mixed with the hemolymph. This new method for arresting horseshoe crab hemocyte agglutination suggests the participation of sulfhydryl groups in the process.

Agglutination↗
PubMed1964

ENDOCRINE CONTROL OF TANNING IN THE CRAYFISH EXOSKELETON.

Tanning of the newly formed exoskeleton of the dwarf crayfish, Cambarellus shufeldti, depends in part upon the presence of a substance from the eyestalk. Injection of eyestalk extract enhances tanning in a specimen with its eyestalks removed, whereas the exoskeleton of an untreated crayfish without eyestalks will not become as dark as that of an intact individual.

Animals↗
PubMed1964

PACEMAKER NEURONS: EFFECTS OF REGULARLY SPACED SYNAPTIC INPUT.

The consequences of inhibitory or excitatory synaptic input between pacemaker neurons were predicted mathematically and through digital-computer simulations, and the predicted behavior was found to occur in abdominal ganglia of Aplysia and in stretch receptors of Procambarus. Discharge patterns under conditions that do not involve interneuronal feedback are characteristic and self-stabilizing. Paradoxically, increased arrival rates of inhibitory input can increase firing rates, and increased excitatory input rates can decrease firing rates.

Animals↗
PubMed1964

ELECTROENCEPHALOGRAMS OF SHARKS.

Patterns of electrical potentials recorded from the brains of sharks exhibit definite relationships to chemical and visual stimuli. Forebrain potentials reflect olfactory processes. Both restrained and free-swimming sharks exhibit mesencephalic responses to light and neural triggering of respiratory reflexes from the medulla. Early evolution of typical vertebrate brain functions, with emphasis upon chemoreception, is indicated

Animals↗
PubMed1964

ADAPTATION IN STRETCH RECEPTOR NEURONS OF CRAYFISH.

Two factors involved in the adaptation in stretch receptor cells of crayfish were separated and studied: (i) the decline of the rate of discharge during intracellular application of constant current and (ii) the decline of generator potential during sustained stretch. The change in generator potential with time was essentially identical in both rapidly and slowly adapting cells. The slowly adapting cells continued to discharge throughout the application of depolarizing currents, whereas the rapidly adapting cells stopped discharging while the current was applied. The different rates of adaptation are therefore attributable to the difference in the properties of the electrically excitable membranes rather than the properties which produce generator potentials.

Acclimatization↗
PubMed1965

ELECTRICAL CONNECTIONS BETWEEN VISUAL CELLS IN THE OMMATIDIUM OF LIMULUS.

When microelectrodes are inserted in two cells of the same ommatidium in Limulus, current applied through the membrane of one cell produces a change in potential across the membrane of both cells. The large spikes recorded from one cell and the small spikes recorded from the other always appear synchronously. However, the small spikes are abolished selectively during the hyperpolarizing response. The discrete waves recorded from eyes adapted to darkness occur simultaneously in cells of the same ommatidium.

Acclimatization↗
PubMed1965

ARTHROPOD PREPARATION FOR BEHAVIORAL, ELECTROPHYSIOLOGICAL, AND BIOCHEMICAL STUDIES.

Electrodes and cannulea can be permanently implanted in the horseshoe crab, Limulus polyphemus. Recordings of electrical activity can be obtained from the optic nerve, heart, and abdominal ganglia and the cannulae are effective routes for introducing isotopes into the nervous system. The animals survive for at least 13 days and are not behaviorally impaired.

Animals↗