Die Nervennetze im Penisretraktor von Helix pomatia

Zusammenfassung Die Nerven des glatten Penisretraktormuskels von Helix pomatia enthalten eine kleine Zahl von verhältnismäßig großen Nervenzellen. Ihre Nervenfasern werden durch Gliazellen zusammengehalten, die reich sind an Gliafilamenten. Offenbar sind diese Nerven wie die anderen Nerven des Tieres Nervennetze. Es gibt Hinweise darauf, daß der Muskel wenigstens 4 verschiedene Transmittersubstanzen enthält.

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The nerve nets of the penis retractor muscle of Helix pomatia

Summary The nerves of the smooth penis retractor muscle of Helix pomatia contain a small number of rather big nerve cells. Their nerve fibers are kept together by glia cells which are rich in glia filaments. Evidently these nerves are nerve nets like the other nerves of the animal. There are signs, that the muscle contains at least 4 different transmitter substances.

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Auf Anregung von Herrn Prof. Schlote; mit Unterstützung durch die Deutsche Forschungsgemeinschaft und die Göttinger Akademie der Wissenschaften.     

Eine Geschwulstbildung bei Helix pomatia L.

Ohne Zusammenfassung     

Nerve cells of Helix pomatia during hypercapnia

Hypercapnia leading initially to activation of synaptic activity and of pace-maker mechanism is accompanied later by inactivation of the electro-excitable membrane and is completed by loss of chemosensitivity. Restoration of the properties of the neurone following transition to normal atmospheric air develops in reverse order. All hypercapnic changes of the properties of the electroexcitable and chemosensitive membrane take place at a constant level of the membrane potential which points to stability of K-Na-pump.     

Tubular polymers derived from Helix pomatia beta-hemocyanin.

Upon trypsinolysis Helix pomatia beta-hemocyanin forms long tubular structures, which appear to be linear polymers of hemocyanin molecules from which the collar structure has been removed. Polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate shows that only few peptide bonds are hydrolyzed by trypsin. The structure of the polymers has been investigated by electron microscopy, combined with optical diffraction. Preliminary X-ray diffraction data are presented. Functional properties of the polymers are similar to those of the native protein. Both show a calciumion-dependent co-operativity of oxygen binding and a Bohr effect. The results suggest that the collar of a hemocyanin molecule has no special function in the process of (co-operative) oxygen binding, different from that of the wall of the molecule.     

Identification of CO2 Chemoreceptors in Helix pomatia

SYNOPSIS. Gas exchange in pulmonate snails of the family Helicidaeoccurs through a highly vascularized diffusion lung known asthe mantle. The extent of ventilation of the mantle dependsupon the duration and size of opening of an occlusible poreknown as the pneumostome. In Helix aspersa and Helix pomatia,pneumostomal size and frequency of opening are exquisitely sensitiveto CO₂. Respiratory CO₂ chemosensitivity resides in a discreteregion of the subesophageal ganglia. The discharge pattern ofmany neurons in the chemoreceptor area changes during stimulationwith CO₂. However, the electrophysiological response to CO,stimulation alone does not discriminate between CO₂ chemoreceptorcells and CO₂-insensitive neurons active in the pneumostomalresponse to CO₂. We identified a subset of CO₂-sensitive neuronsfrom the larger population of neurons active during CO₂ stimulation.The action potential discharge frequency of CO₂ chemosensoryneurons increased in response to CO₂ stimulation. An increaseddischarge frequency of CO₂-sensitive neurons was associatedwith increased pneumostomal opening, and both the size and thefrequency of pneumostomal opening increased during CO₂ stimulation.Injecting depolarizing current into individual chemosensoryneurons elicited opening of the pneumostome in the absence ofCO₂. Action potential generation in response to CO₂ was independentof synaptic transmission. Removal of individual CO₂-sensitivecells or inhibition of action potential generation in CO₂-sensitivecells reduced or eliminated pneumostomal responses to CO₂. CO₂sensitivity in chemoreceptor cells required extracellular calcium,but not sodium. Substituting barium for calcium supported chemoreceptoractivity. In summary, we have identified respiratory related,chemosensory neurons that are CO₂ sensitive in the absence ofsynaptic input.     

Helix pomatia induced conversion of some 3 beta-hydroxysteroids

After incubating a dehydroepiandrosterone solution with an enzymatic preparation from Helix pomatia, the steroid recovery was markedly decreased. The transforming activity resulted specific for some 3 beta-hydroxysteroids and it appeared to lower after storing the preparation at 4 degrees C for some days. The presence of 4-androsten-3,17-dione within the incubation products suggests that the enzymatic preparation contains at least 3 beta-hydroxysteroid: NAD oxydoreductase and 3-oxosteroid-5-4-ene isomerase. The use of large amounts of freshly dissolved Helix pomatia juice solution may lead to unreliable results in steroid analyses.     

Food-attraction conditioning in the snail,Helix pomatia

Adult pulmonate snails (Helix pomatia) were released equidistant between two types of food, carrot and potato, respectively. Naive snails moved in different directions and did not locate either food above chance, although both foods were readily eaten upon direct contact. After a single carrot feeding episode, 75% of the carrot-fed snails moved directly towards the carrot and ate it. Conversely, potato-fed snails located the potato in 67% of the cases. Snails that were fed apple or lettuce behaved like naive animals, with the majority of animals (75% in both cases) locating neither the carrot nor the potato.The ability of snails to locate this particular food after a single feeding episode was maintained for at least 11 days, provided that the snails were not exposed to other foods in the interim. If the animals were fed a different food (but still tested for food-finding ability to the initially conditioned food) their orientation preference decreased gradually over a period of 5 days.Although the snails' orientation is based upon olfactory cues, exposure to food odor alone is not sufficient to enable food-finding; additional feeding related stimuli are necessary.These findings indicate that Helix do not possess a predisposition for the foods tested, and further suggest that processes underlying food-finding and food selection are strongly influenced by learning experiences. The conditioning phenomenon underlying food-finding behavior has been called Food-Attraction Conditioning, and appears to be a crucial link between the ecologies of learning and foraging behaviors. The accessibility of the snail's nervous system should permit neuronal analysis of the mechanisms underlying such a unique and complex learning phenomenon.     

Parvalbumin-immunoreactive neurons in the brain of Helix pomatia

Parvalbumin-immunoreactive material was detected in the central nervous system of the snail, Helix pomatia. Each ganglion investigated contained parvalbumin-immunoreactive neurons. The molecular weight of Helix parvalbumin-immunoreactive material as determined by Western blots is about 40 kilodaltons. ⁴⁵Ca²⁺ overlays showed that this protein binds Ca²⁺. In contrast to vertebrates, in Helix neurons parvalbuminlike material was not colocalized with the neurotransmitter gamma-aminobutyric acid (GABA).     

A modified semi-synthetic diet for bioassay of non-sporeforming entomopathogenic bacteria against Spodoptera litura

Standard semi-synthetic diet used for rearing Spodoptera litura (Fab) larvae contains many antimicrobials. This diet is not suitable for evaluating non-sporeforming bacteria. We determined the effect of antimicrobials present in S. litura semi-synthetic diet on growth of entomopathogenic Serratia marcescens. Nutrient broth supplemented with four and two times reduced doses of sorbic acid (0.15 g) and methyl parahydroxybenzoate (0.05 g) supported bacterial growth comparable to control medium. No growth could be observed even at five times reduced concentrations of formaldehyde and streptomycin sulphate. Diet for rearing S. litura was modified accordingly and validated using two S. marcescens strains. Larval mortality ranged between 20% and 30% on the standard diet and more than 90% in the modified diet.     

A two-component affinity chromatography purification of Helix pomatia arylsulfatase by tyrosine vanadate

The inhibition of Helix pomatia arylsulfatase by the synergistic combination of N-acetyl-l-tyrosine ethyl ester and vanadate has been extended to affinity chromatography for purification. In the presence of vanadate, l-tyrosine ethyl ester (TEE), immobilized on CH-Sepharose 4B retained arylsulfatase from the digestive juice or lyophilized powder of H. pomatia. No enzyme was retained without vanadate or with arsenate or phosphate. Arylsulfatase was eluted from the column matrix by removing the vanadate to less than 50 microM with buffer containing EDTA to chelate the vanadate. Escherichia coli alkaline phosphatase and potato acid phosphatase, two enzymes which are inhibited by vanadate but not by the vanadate-TEE complex, were not retained by the immobilized TEE under any conditions used. The sulfatase activity was completely separated from contaminating glucuronidase activity present in the crude enzyme extracts. The Ki for the immobilized vanadate-TEE system was found to be 5.0 x 10(-7) M with a capacity of 25 mg/ml swollen gel. A purification of greater than 40-fold from the lyophilized powder of H. pomatia (Sigma Type H-5) was achieved using this technique. The Ki/Keq of other phenols with vanadate were determined in a 96-well plate format as an example of a rapid screening technique that could be extended to other phosphoryl and sulfuryl-transfer enzyme classes.     

ADP-ribosyltransferase from Helix pomatia. Purification and characterization.

ADP-ribosyltransferases from several higher eukaryotes have been purified and characterized, but little is known about ADP-ribosyltransferases in lower eukaryotes. We have purified an ADP-ribosyltransferase (EC 2.4.2.30) from Helix pomatia. The enzyme has an apparent Km of 26.7 microM. Optimal conditions for the enzyme reaction are 17.5 degrees C and pH 8. The time course is linear during the first 10 min of the reaction. The enzyme is capable of poly-ADP-ribosylation. The most highly purified preparation shows one major band at an Mr of 75,000 on electrophoresis in an SDS/polyacrylamide gel, with minor bands at Mr 115,000 and 155,000. Re-activation of SDS/polyacrylamide gels in situ shows the 75,000-Mr band to be enzymically active and additional active bands with Mr values of 115,000, 90,000 and 87,000 respectively. The 115,000-Mr and 75,000-Mr bands cross-react with a polyclonal affinity-purified antiserum against human ADP-ribosyltransferase. Like enzymes from higher eukaryotes, the activity from Helix pomatia is inhibited by thymidine, theophylline, theobromine nicotinamide, 3-methoxybenzamide and 3-aminobenzamide, and is dependent on histone and DNA.     

Identification of agglutinin receptors on hemocytes of Helix pomatia

The attachment of opsonized foreign particles to phagocytic cells indicates the occurrence of opsonin receptors on the surfaces of the phagocytes. There is good evidence that naturally occurring hemagglutinins may serve as opsonins in invertebrates. To prove the occurrence of agglutinin receptors on the hemocytes of an invertebrate, the interaction of various agglutinins with Helix pomatia hemocytes was investigated. A positive agglutination reaction was obtained with Ricinus, Axinella, anti-H_eel, Ulex, concanavalin A, and Limulus agglutinins. The known specificities of these agglutinins and the influence of carbohydrases on the agglutinability of Helix cells have led to the conclusion that the carbohydrate components of the binding sites include galactose, fucose, mannose or glucose or both, and N-acetylneuraminic acid or polygalactose.