[Single interneuron coordinates wing and tail movements in pteropod mollusk].

Nervous centers that coordinate rhythmical movements with body stabilization in space are well known in vertebrates. Here we report a single identified interneuron CPB3c (cerebropedal neuron c from group B3) that serves the same function ofpostural control during locomotion in a simple animal model--the marine pteropod mollusk Clione limacina. CPB3c interneuron integrates inputs from statocysts and locomotor generator and translates signals to tail motorneurons.

[Gap junctions in sea anemone, Nematostella vectensis, embryo].

Gap junctions (GJs) are composed of membrane proteins that form channels connecting the cytoplasm of adjacent cells and permeable to ions and small molecules. They are considered to be the main or only type of intercellular channels and a universal feature of all multicellular animals (Metazoa). Till recently, sea anemones and corals (Anthozoa, Cnidaria) appeared to be an exception from this rule.

[Intercellular channels in animals].

Gap junctions are considered to serve a similar function in all multicellular animals (Metazoa). Two unrelated protein families are involved in this function: connexins, which are found only in chordates, and pannexins, which are present in the genomes of both chordates and invertebrates. Recent sequence data from different organisms show important exceptions to this simplified scheme.

[The staining of the central neurons in the pteropod mollusk Clione limacina with fluorescein-labelled alpha-bungarotoxin].

FITC-labelled alpha-bungarotoxin (alpha BT[FITC]) was used to identify acetylcholine (ACh)-sensitive neurons in the central nervous system of pteropod mollusc Clione limacina. Two small symmetrical neurons were stained with alpha BT[FITC] on the dorsal surface of the cerebral ganglia. The staining was highly specific as it was completely blocked by preincubation in alpha-bungarotoxin [alpha BT] at very low concentration (10(-9) M).

[Electrophysiologic study of the serotoninergic neuron C1 in the pteropod mollusk Clione].

Functional characteristics of the cerebral serotoninergic neuron (C1) have been studied in the pteropod mollusc Clione limacina. The C1 neuron axon projected to the buccal ganglia and axon collaterals terminated in buccal nerves. Stimulation of the C1 neuron activated the feeding rhythm generator in the buccal ganglia.

[The generation of locomotor rhythmicity in the nervous system of large and small individuals of the pteropod mollusk Clione limacina].

The marine pteropod mollusc Clone limacina swims due to rhythmic movements of its wings. The frequency of wing oscillations in young molluscs (2-6 mm long) is 5-6 Hz, while in adult molluscs (40-60 mm long) it is 1-2 Hz. The locomotor rhythm is generated by two groups of pedal interneurons (groups 7 and 8) capable of endogenous rhythmic activity.

[The neuronal mechanisms of the escape reaction to stimulation of the statocyst receptors in the freshwater snail].

Tilts of the freshwater snail Planorbarius corneus, resulting in statocyst receptor stimulation, induced the defensive reaction including pulling down of the shell, shortening of the foot, inhibition of locomotion and feeding. The preparation of the central nervous system has demonstrated that many inter- and motoneurons from different ganglia were involved in this reaction. Usually the reaction was of "all or none" manner.

[The neuronal mechanisms of the defensive reaction to stimulation of the cutaneous nerve in the freshwater snail].

The whole body withdrawal reaction of freshwater snail Planorbarius corneus consists of two phases. In the first phase the shell is rapidly moved down to cover the head, in the second one the body is slowly retracted into the shell. The columellar muscle is involved in this behaviour.

[Neuronal mechanisms of the generation of the feeding rhythm in the buccal ganglia of the pteropod mollusk].

Two antagonistic groups of neurons, active in protractor and retractor phases of the feeding cycle, were found in the buccal ganglia of the pteropod mollusc Clione limacina. Neurons within each group are electrically coupled, while the groups inhibit one another. Each group is able to perform independent rhythmic activity.

[Regeneration of neurons of the pedal ganglion of the pteropodal mollusk Clione limacina].

In pedal ganglia of mollusc Clione limacina the growth of axons was studied in motoneurons and interneurons after transections of the wing nerve or of the pedal comissure. Neurons were stained by Lucifer Yellow. In motoneurons, neurites grown both from the transected end of the axon and from the neuron soma spread to all nerve trunks of ipsi- and contralateral ganglia.

[Generation of locomotor rhythms in Limacina helicina].

Two groups of neurons (motoneurons and putative interneurons), exhibiting periodic activity with the locomotory rhythm, were recorded in the pedal ganglia of the isolated nervous system of the mollusc Limacina helicina. Motoneurons periodically generated spike bursts, while interneurons generated only one prolonged (100-400 ms) action potential per cycle. Rhythmic generation persisted after blocking the spike discharges of motoneurons by means of tetrodotoxin.

[Neurons of the pedal ganglia of a pteropod mollusk regulating locomotor generator function].

Neurons whose excitation affected the locomotory rhythm were recorded in the isolated pedal ganglia of the marine mollusc Clione limacina. Some of these neurons generated "plateau" potentials, i.e.

[Synchronization of the work of pedal ganglia of pteropod mollusks during locomotion].

Two wings of the marine mollusc Clione limacina oscillate synchronously during swimming. These movements are controlled by pedal ganglia. Synchronization of rhythmic activities in the ganglia is produced by interneurons of groups 7 and 8 whose axons pass to the contralateral ganglion through the pedal commissure.

[Interneuron activity of the pedal ganglia of pteropod mollusks during generation of locomotor rhythms].

Activity of interneurons from isolated pedal ganglia of marine mollusc Clione limacina was recorded during generation of the locomotor rhythm. Two groups of reciprocally active interneurons were found. These neurons generate one prolonged action potential per locomotory cycle.

[Motor neuron activity of the pedal ganglia of pteropod mollusks during generation of locomotor rhythms].

Activity of motoneurons from pedal ganglia of marine mollusc Clione limacina was recorded during generation of the locomotor rhythm. Motoneuron groups controlling antagonistic wing muscles are active alternatively, excitation of one group being accompanied by inhibition of the other group. Many synergetic motoneurons are electrically coupled.

[Effect of serotonin and theophylline on generation of rhythmic activity in the buccal ganglia of gastropod mollusks].

Effect of serotonin on generation of the feeding rhythm in buccal ganglia was studied in 8 species from 3 subclasses of gastropod molluscs. Serotonin (10(-5) mol/l) initiated or increased the rhythmical activity in the buccal ganglia. The effect of serotonin was potentiated with theophylline (phosphodiesterase inhibitor).

[Vestibular responses of "fast" and "slow" Deiter's nucleus neurons].

The response of vestibulospinal neurons to the tilt in the frontal plane was studied in decerebrate cats. The neurons were identified antidromically by L1 stimulation. The response to the tilt was found to be correlated with the speed of axonal conductance: the neurons responding to the ipsilateral tilt had the latency of the antidromic response 2.

[Depolarization of primary afferents during fictitious scratching of thalamic cats].

The cord dorsum and dorsal root potentials were recorded during fictious scratching in L6 segment of the thalamic cats. It is shown that primary afferent depolrization (PAD) can be modulated by the central generator of scratching. In some afferent fibres antidromic spikes appear on the top of PAD-waves.