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At least 19 recordsLinked to original sources
PubMed1990

Photoperiod and temperature interaction in the determination of reproduction of the edible snail, Helix pomatia.

Snails were kept in self-cleaning housing chambers in an artificially controlled environment. Mating was frequent under long days (18 h light) and rare under short days (8 h light) regardless of whether the snails were kept at 15 degrees C or 20 degrees C. An interaction between photoperiod and temperature was observed for egg laying. The number of eggs laid (45-50/snail) and the frequency of egg laying (90-130%) were greater in long than in short days (16-35/snail and 27-77%) but a temperature of 20 degrees C redressed, to some extent, the inhibitory effect of short days. At both temperatures only long photoperiods brought about cyclic reproduction over a period of 16 weeks, confirming the synchronizing role of photoperiod on the neuroendocrine control of egg laying in this species of snail.

Animals↗
PubMed1992

Accumulation and excretion of aluminium and iron by the terrestrial snail Helix aspersa.

1. The snail Helix aspersa was fed one 24 hr meal containing Al, Fe or both together in barley flour pellets. Accumulation and distribution within the digestive gland, kidney, crop and remaining soft tissues were examined over the subsequent 30 days using atomic absorption spectroscopy (A.A.S.). 2. The digestive gland contained significantly (P < 0.05) elevated levels of Al and Fe for 8 and 12 days. The digestive gland is the major sink for both Al and Fe in Helix. 3. The kidney rapidly accumulated Al and Fe but the increase was short-lived. The kidney may therefore be involved in the elimination of metal not incorporated into the digestive gland. 4. Iron was absorbed by the crop but Al was not. This may indicate a route of uptake of Fe into the digestive gland not shared with Al. 5. No obvious pattern of accumulation of Al and Fe were seen in the remaining soft tissues or the blood of Helix. 6. Aluminium is present in the faeces for 12 days suggesting that Al is released relatively slowly. 7. Presence of both Al and Fe in the feed induced a change in the pattern of accumulation in the digestive gland but not in the kidney, crop and remaining soft tissues. 8. The distribution of Al is discussed in relation to the suggestion that Al follows the ferretin pathway during accumulation.

Aluminum↗
PubMed1989

Sugar and amino acid intestinal transport systems in land snail Helix aspersa.

The intestine of Helix aspersa snail is able to actively transport sugars and amino acids. D-glucose, D-galactose and 3-oxymethylglucose share the same transport system with competitive inhibition between them, which is strictly Na(+)-dependent. Phlorizin has high affinity for that system and inhibits it competitively. D-fructose and L-arabinose are not actively transported, do not inhibit the transport of other sugars, and enter the tissue at a lineal rate with their concentration, which coincides with that of mannitol and with that of actively transportable sugars in the presence of 10(-4)M phlorizin. Galactose seems to enter the tissue from the serosal side through another carrier, with different specificity, Na(+)-independent, inhibited by phloretin but not by phlorizin. There are also transport systems for neutral amino acids, for the basic ones and for imino acids. Neutral amino acids present affinity for the other systems, whereas the basic ones and the imino acids seem to use only those proper to them. The system for imino acids is strictly Na(+)-dependent, but neutral amino acids and the basic ones continue to be transported and accumulated, although to a lesser extent, in the absence of Na+. Transport of sugars and amino acids is scarcely O2 dependent, although it is inhibited by 10(-4)M DNP. It is also partially inhibited by harmaline and by ouabain.

Amino Acids↗
PubMed1977

Isolation of nematode inhibitor from hemolymph of the snail, Helix aspersa.

Hemolymph plasma of the snail Helix aspersa which inhibits maturation and reproduction of its mantle cavity-inhabiting nematode, Rhabditis maupasi, was separated biochemically for the active proteinaceous component. Isolation of the active inhibitor was performed using ion-exchange chromatography in combination with subsequent gel filtration. The isolated peaks were bio-assayed in vitro on nematode larvae. The fractions harboring inhibitory protein suppressed larval growth and adult reproduction in vitro. The isolated fraction was purified by gel filtration and characterized on the basis of a single band on starch zone electrophoresis and positive reaction only with folin-phenol reagent.

Animals↗
PubMed1978

The accumulation of DL-glutamate by the central nervous system of the snail Helix pomatia.

Isolated snail ganglia are capable of maintaining their free amino acid levels steady for the first 60 min of incubation in physiological saline. Within this time the ganglia also possess an uptake mechanism for DL-glutamate which can be divided into sodium-sensitive and -insensitive components. The accumulation of DL-glutamate showed saturation kinetics typical of a carrier-mediated process. The Vmax value for the uptake is 1.5 x 10(-8) mole/g/min and the Km value 1.1 x 10(-4) M. The amino acid accumulation is quite specific towards L-dicarboxylic acids and insensitive to a number of metabolic inhibitors. It is unlikely to be due to a homoexchange phenomenon because the ganglia are capable of achieving a net uptake of glutamate and the efflux of DL-[3H]glutamate is not increased by the addition of non-radioactive L-glutamate to the incubation medium.

Amino Acids↗
PubMed1990

Structural studies on the galactan from the snail Helix pomatia.

1. The galactan of the snail Helix pomatia was subjected to two cycles of Smith-degradation and the resulting products were isolated by gel filtration and thin layer chromatography. 2. The structures of the low molecular weight oligosaccharides were elucidated being identical to those obtained from Lymnaea stagnalis galactan. However, the quantities released differed significantly between the two species. The high molecular fractions comprising about 66% of the material were not obtained in a similar degradation of the Lymnaea stagnalis galactan. 4. Thus the observed structural differences can explain easily the species-specific reactivity among the two polysaccharides seen earlier with lectins, enzymes and antibodies.

Animals↗
PubMed1977

[Differentiation of the prostate in the snail Helix aspersa Müll].

The differentiation of the snail Helix aspersa prostate gland is studied in animals from one to six months old. After the presentation of organogenesis the primary stage of secretion (3 months) and a stage where the prostate gland shows abundant secretions (6 months) were described; but the oviduct is still indifferentiated. The ultrastructural analysis shows the formation of secretory and ciliated cells in epithelioid prostatic tubes.

Animals↗
PubMed1992

Immunochemical characterisation of tachykinin immunoreactivity in the nervous system of the garden snail, Helix aspersa.

1. Circumoesophageal ganglia and foot muscle of the garden snail, Helix aspersa, were subjected to immunocytochemistry using antisera to the tachykinins, substance P (SP), neurokinin A (NKA), kassinin (KAS) and eledoisin (ELE). 2. Immunoreactivity in neuronal somata and fibres was detected only with the SP antiserum. 3. SP and NKA radioimmunoassays were performed on extracts of circumoesophageal ganglia. In common with immunocytochemistry, immunoreactivity was only detected with the SP antiserum. 4. Gel permeation chromatography of extracts resolved a single peak of immunoreactivity eluting slightly later than synthetic mammalian SP. Reverse-phase HPLC of immunoreactive fractions resolved two immunoreactive peptides representing oxidised and reduced forms of a single peptide. 5. These data suggest that the nervous system of H. aspersa contains a single tachykinin with C-terminal structural characteristics similar to mammalian SP.

Amino Acid Sequence↗
PubMed1979

Motor innervation of the pharynx levator muscle of the snail, Helix pomatia: physiological and histological properties.

(1) Motor innervation of the pharynx levator muscle of Helix pomatia was investigated with intracellular recording and axonal iontophoresis of cobalt chloride. (2) Muscle fibers respond to direct electrical stimulation of the muscle with active graded responses or non-overshooting spike potentials. (3) Each fiber is innervated via the external and internal lip nerves by several (mostly 3) excitatory nerve fibers each. Two types of EPSPs can be distinguished according to amplitude, duration, and facilitation. (4) Axonal CoCl2-staining via an external lip nerve branch revealed many nerve fibers entering the muscle and branching there into a rich network of blebbed fibers of various diameters.

Animals↗
PubMed1979

Electron microscopic studies on radular tooth formation in the snails Helix pomatia L. and Limax flavus L. (Pulmonata, Stylommatophora).

The radular teeth are secreted at the posterior end of the radular gland and move slowly towards the buccal cavity where they start to function. Helix pomatia and Limax flavus were examined to determine whether the newly formed teeth already show their definite species specific shape, or whether they are gradually finished and moulded in the radular gland. Scanning electron micrographs of Helix pomatia show that teeth are secreted in the odontoblast region in their final form. Their surface is still uneven at the outset; the same is true for the newest teeth of Limax flavus. Older teeth ready for use have a smooth surface. This change seems to be brought about by secretory activity of the superior epithelium of the radular sac. Air-dried radulae, previously isolated by KOH maceration, show considerable artefacts at their posterior end. Maceration leads to shrinking of the newest teeth, but does not change their contours. The newly secreted but as yet unhardened teeth become greatly deformed during the drying process.

Cytoplasm↗