Planorbis corneus L. als Collembolenfreser (Apterygota, Collembola)

1957 ◽  
Vol 16 (2) ◽  
pp. 32-32
Keyword(s):  
Planorbis Corneus

Pflanzenabwehrstoffe XXXI [1] Molluskizide Eigenschaften von Chinonen

1987 ◽  
Vol 42 (1-2) ◽  
pp. 31-32 ◽  
Author(s):  
Hermann Schildknecht ◽  
Johannes Lubosch
Keyword(s):  
Planorbis Corneus ◽  
Molluscicidal Activity

Abstract The quinone 2-methoxy-6-n-pentyl-2,5-cyclohexadien-1,4-dion (Primin) was found to possess molluscicidal activity against the snail Planorbis corneus. The synthesis of homologous and isomers and the results in the biotests are reported.

Control of feeding movements in the freshwater snail Planorbis corneus

1988 ◽  
Vol 70 (2) ◽  
pp. 332-341 ◽  
Author(s):  
Yu. I. Arshavsky ◽  
T. G. Deliagina ◽  
G. N. Orlovsky ◽  
Yu. V. Panchin
Keyword(s):  
Freshwater Snail ◽  
Planorbis Corneus

Problems associated with the use of tetraethylammonium to test for monosynaptic connexions

1975 ◽  
Vol 62 (3) ◽  
pp. 797-803
Author(s):  
M. S. Berry ◽  
V. W. Pentreath
Keyword(s):  
Nervous System ◽  
Transmitter Release ◽  
Gastropod Mollusc ◽  
Postsynaptic Response ◽  
Postsynaptic Potential ◽  
Planorbis Corneus

Several investigators of the molluscan nervous system have used TEA, injected into presynptic neurones, to determine whether the connexions made by these neurones are monosynaptic. The increase in spike duration produced by the TEA causes an increase in transmitter release, and hence an increase in the amplitude of the postsynaptic potential if the connexion is direct. If the connexion is indirect, the spike in an intercalated neurone will not be affected by the TEA, and the postsynaptic response will remain constant. Experiments described here show that TEA can cross electrotonic junctions in the gastropod mollusc Planorbis corneus. They also show that each TEA-prolonged presynaptic impulse may produce more than one postsynaptic impulse. A larger postsynaptic potential could therefore be produced by presynaptic injection of TEA in the case of an indirect connexion. This indicates that care must be taken when interpreting the results of experiments using TEA to test for monosynaptic connexions.

A System of Electrically Coupled Small Cells in the Buccal Ganglia of the Pond Snail Planorbis Corneus

1972 ◽  
Vol 56 (3) ◽  
pp. 621-637
Author(s):  
MICHAEL S. BERRY
Keyword(s):  
Synaptic Input ◽  
Action Potentials ◽  
Burst Activity ◽  
Small Cells ◽  
Pond Snail ◽  
Trigger System ◽  
Buccal Ganglia ◽  
Large Numbers ◽  
Planorbis Corneus

1. The buccal ganglia of Planorbis contain a population of electrically coupled small cells. This has been studied, in preparations of isolated ganglia, by recording intracellularly from the cells two at a time. 2. The population is usually silent but activity initiated in any one of its members tends to spread to the rest of the population in both ganglia. Failure of spread, or fatigue, gradually occurs on repetition. 3. The group has the properties of a trigger system, initiating prolonged patterned activity in large numbers of neurones in the buccal ganglia. This may normally initiate feeding. 4. In addition to central processes, both in the buccal ganglia and to the rest of the CNS, the system has peripheral axons in most of the buccal nerves. No synaptic input could be demonstrated. 5. Action potentials in some of the cells increase greatly in duration with repetition. The resulting electrotonic EPSP's, recorded in closely coupled trigger cells, correspondingly increase in size. The possible integrative significance of this is discussed, especially its effect in offsetting fatigue. 6. In some preparations spontaneous bursting occurred in trigger cells and this elicited burst activity in large neurones, including motoneurones. The system may have an intrinsic pacemaker.

Further identification of multiple responses mediated by dopamine in the CNS of Planorbis corneus

1978 ◽  
Vol 56 (1) ◽  
pp. 7-18 ◽  
Author(s):  
J. F. MacDonald ◽  
M. S. Berry
Keyword(s):  
Neuroleptic Drugs ◽  
Intracellular Recordings ◽  
Excitatory Postsynaptic Potentials ◽  
Multiple Responses ◽  
Gastropod Mollusc ◽  
Postsynaptic Potentials ◽  
Synaptic Potentials ◽  
Inhibitory Postsynaptic Potentials ◽  
Planorbis Corneus ◽  
Synaptic Responses

Intracellular recordings from neurones, receiving monosynaptic contacts from a dopamine-containing (DA-containing) neurone in the central ganglia of the gastropod mollusc Planorbis corneus, revealed that there are at least three DA-mediated responses. These are 'fast' excitatory postsynaptic potentials (EfPSPs) (200 ms), 'slow' excitatory postsynaptic potentials (EsPSPs) (900 ms), and inhibitory postsynaptic potentials (IPSPs) (200–900 ms). Various combinations of these synaptic potentials were recorded from postsynaptic neurones: EsPSPs, EfPEPs, EsEfPSPs, or EfIPSPs. Neurones receiving such connections also responded appropriately to iontophoresized DA with a 'fast' depolarization (EfPSPs), a 'slow' depolarization (EsPSPs), or a hyperpolarization (IPSPs). These responses could be distinguished on the basis of function (excitation or inhibition), duration, rate of desensitization, and sensitivity to apomorphine, D-LSD, and tubocurarine. The neuroleptic drugs (DA antagonists) haloperidol, fluphenazine, and metoclopramide reduced both excitatory and inhibitory DA transmission. This investigation strongly supports the hypothesis that DA is the transmitter mediating multiple synaptic responses in Planorbis.

The glial cells and glia—neuron relations in the buccal ganglia of Planorbis corneus (L): cytological, qualitative and quantitative changes during growth and ageing

1985 ◽  
Vol 307 (1133) ◽  
pp. 399-456 ◽  
Keyword(s):  
Small Molecules ◽  
Glial Cell ◽  
Glial Cells ◽  
Qualitative And Quantitative ◽  
Buccal Ganglia ◽  
Occluding Junctions ◽  
Planorbis Corneus ◽  
Cell Processes ◽  
Quantitative Changes

The glial tissue in Planorbis ganglia surrounds and ensheaths the neurons. The majority of the glial processes are interwoven around the neuronal perikarya and their major axon branches. Glial cell processes form a layer between the blood and nerve perikarya, but this does not significantly interfere with the movements of many small molecules in and out of the tissue. Such movements can occur paracellularly, through the extracellular spaces, since there are no occluding junctions between the cells.

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