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At least 19 recordsLinked to original sources
PubMedDate not supplied

Infection of Lymnaea truncatula and Lymnaea glabra by Fasciola hepatica and Paramphistomum daubneyi in farms of central France.

Natural infection of Lymnaea glabra and Lymnaea truncatula by Fasciola hepatica and/or Paramphistomum daubneyi was studied at two periods of risk (June-July and September-October) in 11 French farms known for their high prevalences of F. hepatica infection in ruminants. A total of 1,778 L. truncatula and 2,396 L. glabra measuring 6 mm or more in height were collected to determine the prevalence of natural infection with F. hepatica and P. daubneyi. The role of four factors, i.e. season, snail co-infection (F. hepatica-P. daubneyi), ruminant host and the existence of single or mixed intermediate host communities, was investigated. There were no differences in prevalences between the two risk periods. Co-infections in L. glabra were more frequent than expected. The prevalences of infection with F. hepatica or P. daubneyi in L. glabra were higher in farms rearing sheep than in farms rearing cattle. A similar finding was also noted for L. truncatula infected with P. daubneyi only. L. glabra was a much better intermediate host for F. hepatica and P. daubneyi when it was the only available snail, possibly indicating an adaptation of parasites to their less usual host in local conditions. The two trematodes preferably developed in L. truncatula rather than in L. glabra when both host species lived in the same places.

Animals↗
PubMed2003

Bioconcentration of cadmium and toxic effects on life-history traits of pond snails (Lymnaea palustris and Lymnaea stagnalis) in laboratory bioassays.

We studied the bioconcentration and the individual effects of Cd on life-history traits of Lymnaea stagnalis and Lymnaea palustris exposed to increasing Cd concentrations for 4 weeks in controlled conditions. Internal Cd concentrations were linearly correlated to Cd concentrations of exposure in both foot and viscera of L. stagnalis and in the foot of L. palustris, and they were linked by a logistic relationship with environmental contamination in the viscera of L. palustris. If LC50S were higher than the highest Cd concentrations of exposure (L. stagnalis: 160 microg L(-1); L. palustris: 320 microg L(-1)), other dose-dependent responses affecting life-history traits were noted in both species. In L. stagnalis, EC50 for growth was evaluated at 142 microg L(-1) and growth inhibition was correlated with internal Cd concentrations by a linear relationship. L. palustris was more sensitive to Cd than L. stagnalis because its EC50-growth was three times lower (58 microg L(-1) after 28 days). Dose-dependent responses were obtained for several parameters of fecundity of L. palustris. EC50 for the mean number of egg masses or mean number of eggs per individual were close to 60 microg L(-1), whereas for the mean number of eggs per egg mass, the EC50 was higher, with a value of 124 microg L(-1). The percentage of hatching versus the total number of eggs was 60% in controls, and no embryos were able to hatch at the lowest tested Cd concentration, 40 microg L(-1). The high sensitivity of fertility was due to Cd blocking embryo development, particularly for the latest embryonic stages just before hatching. The present results constitute useful data to develop laboratory tests using pond snails for freshwater risk assessment.

Animals↗
PubMed2002

Development of the nitric oxide/cGMP system in the embryonic and juvenile pond snail, Lymnaea stagnalis L. A comparative in situ hybridization, histochemical and immunohistochemical study.

Recent studies have indicated that nitric oxide (NO)-induced cGMP synthesis is involved in different steps of neurogenesis in invertebrates. The development of putative NO synthetising elements was described earlier in the embryonic and juvenile pond snail, Lymnaea stagnalis, applying NADPH-diaphorase histochemistry (Serfozo et al., 1998). In the present study, we examined the distribution of NO synthase (NOS) during Lymnaea development by in situ hybridization for Lymnaea-NOS mRNA, histochemical, and immunohistochemical techniques for the NOS and NO-stimulated cGMP. Peripheral fibers projecting to the CNS and terminating in the ganglionic neuropils showed NOS immunoreactivity from 85% of embryonic development. At the same time, a fine dot-like, immunostaining indicated the presence of cGMP in the neuropil area. In the CNS, Lymnaea-NOS mRNA positive, as well as NOS and cGMP immunoreactive perikarya were detected first during postembryonic development; their number significantly increased from P3 juvenile stage. Some of the cell groups in the CNS containing NOS immunoreactive material also displayed Lymnaea-NOS mRNA hybridization signal and were cGMP-positive. However, in the subesophageal ganglia, the distribution of Lymnaea-NOS mRNA positive cell groups did not correspond to that of the NOS immunoreactive cells. Neurons revealing transient NOS and cGMP immunoreactivity, respectively, could also be detected in this part of the CNS. In most of the ganglia the number of Lymnaea-NOS mRNA containing and cGMP immunopositive neurons, respectively, exceeded that of the NOS immunoreactive cells from P4 juvenile stage. The localization of NADPH-diaphorase reaction also correlated well with that of the NOS immunoreactivity in the developing CNS. At the periphery, colocalization of Lymnaea-NOS mRNA signal, NOS and cGMP immunoreactivities were observed in the epithelial cells of the esophagus and mantle after hatching. The findings suggest the functional maturity of the NO/cGMP signal transduction pathway at both central and peripheral levels during the development of the snail, Lymnaea stagnalis. The differences in the localization of Lymnaea-NOS mRNA labeling and NOS immunoreactivity in the CNS and PNS can be explained by the existence of different NOS isoforms, posttranslational regulation of NOS, and/or some non-specific antibody labeling.

Animals↗
PubMed1999

Family of prohormone convertases in Lymnaea: characterization of two alternatively spliced furin-like transcripts and cell-specific regulation of their expression.

The majority of neuropeptides in Lymnaea stagnalis are proteolytically processed from larger precursors at sites composed of single or multiple basic amino acid residues. Previous studies have identified several putative prohormone convertases in the brain of Lymnaea. To characterize the complete family, we undertook three independent approaches: reverse-transcribed polymerase chain reaction screening, and low-stringency cDNA and genomic library screenings. The central nervous system cDNA library screening yielded two cDNAs encoding Lfurin1 and its variant form, Lfurin1-X. Both proteins show the characteristic organization of (human) furin with a putative catalytic domain, a P domain, a Cys-rich domain, a transmembrane domain, and a cytoplasmic tail. Lfurin1 and Lfurin1-X are identical, apart from a putative alternatively spliced noncatalytic luminal protein domain, which is present exclusively in Lfurin1-X. In situ hybridization revealed that the Lfur1 gene is expressed throughout the Lymnaea brain, but that the level varies considerably from one neuron to another. Quantitative analysis of the expression level of the two alternatively spliced transcripts revealed that it is neuron type-specifically regulated. This probably indicates the functional importance of noncatalytic luminal protein domains in these enzymes. In addition, our findings suggest that apart from the identified convertases LPC2, Lfurin1/Lfurin1-X, and Lfurin2, additional prohormone convertase diversity is either not present or present only at low levels in the Lymnaea brain. Alternatively, additional prohormone convertases could exist with a lower degree of sequence conservation than the other Lymnaea prohormone convertase members. From our findings, it appears that the majority of prohormone processing in Lymnaea is carried out by the three thus far identified types of Kex2-related prohormone convertases despite the large number of neuropeptide precursors and diverse multiple basic cleavage sites hydrolyzed.

Alternative Splicing↗
PubMed2000

Different extrinsic trophic factors regulate neurite outgrowth and synapse formation between identified Lymnaea neurons.

The requirement for trophic factors in neurite outgrowth is well established, though their role in synapse formation is yet to be determined. Moreover, the issue of whether the trophic factors mediating neurite outgrowth are also responsible for synapse specification has not yet been resolved. To test whether trophic factors mediating neurite outgrowth and synapse formation between identified neurons are conserved in two molluscan species and whether these developmental processes are differentially regulated by different trophic factors, we used soma-soma and neurite-neurite synapses between identified Lymnaea neurons. We demonstrate here that the trophic factors present in Aplysia hemolymph, although sufficient to induce neurite outgrowth from Lymnaea neurons, do not promote specific synapse formation between excitatory partners. Specifically, the identified presynaptic neuron visceral dorsal 4 (VD4) and postsynaptic neuron left pedal dorsal 1 (LPeD1) were either paired in a soma-soma configuration or plated individually to allow neuritic contacts. Cells were cultured in either Lymnaea brain-conditioned medium (CM) or on poly-L-lysine dishes that were pretreated with Aplysia hemolymph (ApHM), but contained only Lymnaea defined medium (DM; does not promote neurite outgrowth). In ApHM-coated dishes containing DM, Lymnaea neurons exhibited extensive neurite outgrowth, but appropriate excitatory synapses failed to develop between the cells. Instead, inappropriate reciprocal inhibitory synapses formed between VD4 and LPeD1. Similar inappropriate inhibitory synapses were observed in Aplysia hemolymph-pretreated dishes that contained dialyzed Aplysia hemolymph. These inhibitory synapses were novel and inappropriate, because they do not exist in vivo. A receptor tyrosine kinase inhibitor (Lavendustin A) blocked neurite outgrowth induced by both Lymnaea CM and ApHM. However, it did not affect inappropriate inhibitory synapse formation between the neurons. These data demonstrate that neurite outgrowth but not inappropriate inhibitory synapse formation involves receptor tyrosine kinases. Together, our data provide direct evidence that trophic factors required for neurite outgrowth are conserved among two different molluscan species, and that neurite extension and synapse specification between excitatory partners are likely mediated by different trophic factors.

Animals↗
PubMed2001

Structure, localization and potential role of a novel molluscan trypsin inhibitor in Lymnaea.

Eggs and egg masses of the freshwater gastropod mollusc Lymnaea provide a microenvironment for developing embryos. Secretions of the exocrine albumen gland of Lymnaea are packaged in the eggs of an egg mass before the eggs are laid externally. The perivitelline fluid that directly surrounds individual oocytes is the main source of nutrition for developing embryos. During early stages of development, the perivitelline fluid is initially internalized by pinocytosis and degraded by lysosomes; in later stages, the embryo ingests the fluid. We previously found that the albumen gland produces large amounts of Lymnaea epidermal growth factor. The albumen gland also appears to produce significant amounts of a novel Lymnaea trypsin inhibitor (LTI), a second peptide that was purified and characterized from Lymnaea albumen gland extracts. The primary structure was determined by microsequence analysis, mass spectrometry, and C-terminal sequence analysis, and showed that LTI is a 57-residue glycosylated peptide. Comparison of the LTI sequence with other known serine protease inhibitors indicates that LTI is a member of the bovine pancreatic trypsin inhibitor family. Reverse phase-high performance liquid chromatography, microsequence analysis, mass spectrometry, and immunocytochemistry demonstrated that abundant amounts of intact LTI are packaged in egg masses. The presence of a trypsin inhibitor in the perivitelline fluid compartment of the egg mass may minimize digestion of peptides and proteins in the perivitelline fluid that are important for the development of the embryo, for example, Lymnaea epidermal growth factor.

Alkylation↗
PubMed1998

The lymnaea cardioexcitatory peptide (LyCEP) receptor: a G-protein-coupled receptor for a novel member of the RFamide neuropeptide family.

A novel G-protein-coupled receptor (GRL106) resembling neuropeptide Y and tachykinin receptors was cloned from the mollusc Lymnaea stagnalis. Application of a peptide extract from the Lymnaea brain to Xenopus oocytes expressing GRL106 activated a calcium-dependent chloride channel. Using this response as a bioassay, we purified the ligand for GRL106, Lymnaea cardioexcitatory peptide (LyCEP), an RFamide-type decapeptide (TPHWRPQGRF-NH2) displaying significant similarity to the Achatina cardioexcitatory peptide (ACEP-1) as well as to the recently identified family of mammalian prolactin-releasing peptides. In the Lymnaea brain, the cells that produce egg-laying hormone are the predominant site of GRL106 gene expression and appear to be innervated by LyCEP-containing fibers. Indeed, LyCEP application transiently hyperpolarizes isolated egg-laying hormone cells. In the Lymnaea pericardium, LyCEP-containing fibers end blindly at the pericardial lumen, and the heart is stimulated by LyCEP in vitro. These data confirm that LyCEP is an RFamide ligand for GRL106.

Action Potentials↗
PubMed2000

Mytilus inhibitory peptides (MIP) in the central and peripheral nervous system of the pulmonate gastropods, Lymnaea stagnalis and Helix pomatia: distribution and physiological actions.

The distribution and neuroanatomy of Mytilus inhibitory peptides (MIP)-containing neurons in the central nervous system and their innervation pattern in the peripheral nervous system of the pulmonate snail species, Lymnaea stagnalis and Helix pomatia, have been investigated immunocytochemically, by applying an antibody raised to GSPMFVamide. A significant number of immunoreactive neurons occurs in the central nervous system of both species (Lymnaea: ca 600-700, Helix: ca 400-500), but their distribution is different. In Lymnaea, labeled neurons are found in all central ganglia where a number of large and giant neurons, previously identified physiologically, reveal MIP immunoreactivity. In Helix, most of the immunolabeled neurons are small (12-30 microm) and concentrated in the buccal and cerebral ganglia; the parietal ganglia are free of labeled cells. In both species, the ganglionic neuropils, peripheral nerves, connectives, and commissures are richly supplied with immunolabeled fibers. The MIP-immunoreactive innervation pattern in the heart, intestine, buccal mass and radula, and foot is similar in both species, with labeled axonal bundles and terminal-like arborizations (buccal mass, foot) or a network of varicose fibers (heart, intestine). Intrinsic neurons are not present in these tissues. The application of GSPYFVamide inhibits the spontaneous contractions of the esophageal longitudinal musculature in Helix, indicating the bioactivity of the peptide. An outside-out patch-clamp technique has demonstrated that GSPYFVamide opens the K+ channels in central nerve cells of Helix. Injection of GSPYFVamide into the body cavity inhibits the feeding of starved Helix. A wide modulatory role of MIP at central and peripheral levels is suggested in Lymnaea and Helix, including the participation in intercellular signalling processes and remote neurohormonal-like control effects.

Animals↗
PubMed1996

Identification and localization of a [Met5]-enkephalin-like peptide in the mollusc, Lymnaea stagnalis.

The goal of this study was to determine whether [Met5]-enkephalin, or an analog, is present in identified neurons in the central nervous system (CNS) of the freshwater snail, Lymnaea stagnalis. High performance liquid chromatography and radioimmunoassay of CNS tissue homogenates revealed both [Met5]-enkephalin and oxidized [Met5]-enkephalin. NO [Leu5]-enkephalin, [Met5]-enkephalin-Arg6-Phe7 or [Met5]-enkephalin-Arg6-Gly7-Leu8 were detected. Quantification of [Met5]-enkephalin, by radioimmunoassay, revealed that the Lymnaea CNS contains approximately 2.2 fmol/CNS (undigested tissue) and 4.5 fmol/CNS (tissue enzymatically digested with trypsin and carboxypeptidase B). The increased amount of [Met5]-enkephalin following tissue digestion indicates the presence of as yet unidentified extended forms of [Met5]-enkephalin in Lymnaea. Using indirect immunocytochemistry, a [Met5]-enkephalin-like peptide was localized to individual cells and cell clusters within the CNS, as well as to fibers in the atrium of the heart. A neuronal map depicting [Met5]-enkephalin-like immunoreactive cells was produced. Among the immunoreactive neurons were four identified, well-characterized, giant cells: VD1, RPD2, LB1 and RB1. Identifiable [Met5]-enkephalin-like immunoreactive neurons were characterized electrophysiologically and morphologically. Additionally, neurons VD1 and RPD2 were confirmed to be immunoreactive to Lymnaea alpha-peptide. The lack of both cross reactivity and sequence homology between alpha-peptide and [Met5]-enkephalin suggests that a [Met5]-enkephalin-like peptide and alpha-peptide are co-localized within these neurons.

Animals↗
PubMed1992

Evolution of the vasopressin/oxytocin superfamily: characterization of a cDNA encoding a vasopressin-related precursor, preproconopressin, from the mollusc Lymnaea stagnalis.

Although the nonapeptide hormones vasopressin, oxytocin, and related peptides from vertebrates and some nonapeptides from invertebrates share similarities in amino acid sequence, their evolutionary relationships are not clear. To investigate this issue, we cloned a cDNA encoding a vasopressin-related peptide, Lys-conopressin, produced in the central nervous system of the gastropod mollusc Lymnaea stagnalis. The predicted preproconopressin has the overall architecture of vertebrate preprovasopressin, with a signal peptide, Lys-conopressin, that is flanked at the C terminus by an amidation signal and a pair of basic residues, followed by a neurophysin domain. The Lymnaea neurophysin and the vertebrate neurophysins share high sequence identity, which includes the conservation of all 14 cysteine residues. In addition, the Lymnaea neurophysin possesses unique structural characteristics. It contains a putative N-linked glycosylation site at a position in the vertebrate neurophysins where a strictly conserved tyrosine residue, which plays an essential role in binding of the nonapeptide hormones, is found. The C-terminal copeptin homologous extension of the Lymnaea neurophysin has low sequence identity with the vertebrate counterparts and is probably not cleaved from the prohormone, as are the mammalian copeptins. The conopressin gene is expressed in only a few neurons in both pedal ganglia of the central nervous system. The conopressin transcript is present in two sizes, due to alternative use of polyadenylylation signals. The data presented here demonstrate that the typical organization of the prohormones of the vasopressin/oxytocin superfamily must have been present in the common ancestors of vertebrates and invertebrates.

Amino Acid Sequence↗
PubMed1989

Age-related changes in female reproductive activity and growth in the mollusc Lymnaea stagnalis.

Age-related changes in reproduction and growth of the pulmonate snail Lymnaea stagnalis were studied in animals under standard culture conditions. Longitudinal studies as well as cross-sectional studies were done. Egg-laying activity starts in Lymnaea at an age of about 2 months. Up to an age of about 250 days it increases, and in older snails it decreases with age. Cross-sectional studies showed that the increase in egg-laying activity is due to an increase in the number of animals that lay eggs and to an increase in the egg-laying frequency of individuals. The decrease in egg-laying activity is due to a decrease in the egg-laying frequency of individual animals and to an increase in the number of animals that stop egg laying. Growth (shell length and body weight) ceases at about the same age at which egg laying begins to decrease. The results are discussed in relation to the organization of the neuroendocrine system in Lymnaea and to results of earlier studies on age-related changes in peptidergic neurons in the CNS of Lymnaea.

Aging↗
PubMed2000

Modulation in firing pattern and oscillation in nerve cells of Lymnaea during network reconstruction.

The modulation and reconstruction of the cardio-respiratory neural circuit of Lymnaea stagnalis L. was compared to that of Helix ponatia L. where the input variation and signal molecules were found to have primary importance in network reorganization. From the cardio-respiratory circuit only neurons connected by afferent or efferent pathways to the peripheral chemosensory organ, the osphradium, were used. It was shown that, the general principles of the network reorganization is similar in the two species. The firing pattern of the neurons altered in Lymnaea depending on the input activation or presence of signal molecules in the vicinity of the neurons. The responses of the neurons to the same sensory information, originating from osphradium varied depending on their firing patterns. On central neurones the generation of phasic pattern and/or oscillation was an indicator of network disintegration leading to insensibility to the osphradial sensory inputs. Co-application of signal molecules (5HT, DA, GABA with opioid peptides) to the neurons caused a phasic firing pattern and/or oscillation leading to disintegration of one network and activation of another one. The effect of mu-opioid peptides on GABA-induced and voltage activated ion currents were shown to be the cellular target in reconstruction of neural networks in Lymnaea. The neural network reconstruction in vertebrate brain evoked by signal molecules can be compared to that observed in the identified network of Lymnaea stagnalis making this latter a useful model in further studies, too.

Animals↗
PubMed1995

Degeneration of CDCs and egg laying in the pond snail Lymnaea stagnalis.

In the pond snail Lymnaea stagnalis egg laying is induced by multiple peptides, which are released by the neuroendocrine caudo-dorsal cells (CDCs). Egg laying in Lymnaea starts at about 50 days and increases initially with age to decreases again at an age of about 250 days. From that age on, the total number of animals that stop egg laying increases with age. The maximum age of Lymnaea is about 660 days. Lucifer Yellow fills of individual ventral CDCs showed reduced branching patterns in old animals. Immunocytochemical stainings demonstrated degeneration in ventral, dorsal and lateral CDCs. In animals that had stopped egg laying, CDCs could still be electrically activated. Regeneration studies after crushing the cerebral commissure showed that in old animals CDCs still can regenerate connections in the cerebral commissure. The properties of CDCs in old animals are discussed in relationship with possible mechanisms of cessation of egg laying in Lymnaea.

Aging↗
PubMed1997

Cloning, characterization, and expression of a G-protein-coupled receptor from Lymnaea stagnalis and identification of a leucokinin-like peptide, PSFHSWSamide, as its endogenous ligand.

Neuropeptides are known to be important signaling molecules in several neural systems of the pond snail Lymnaea stagnalis. Although the functions of these peptides have been studied in many neurons, the nature of the postsynaptic signal transduction is mainly unknown. The cloning and characterization of neuropeptide receptors in Lymnaea thus would be very valuable in further elucidating peptidergic pathways. Indirect evidence suggests that these neuropeptides operate via G-protein-coupled mechanisms indicating the presence of G-protein-coupled receptors as the initial postsynaptic targets. Here we describe the cloning of a neuropeptide receptor from Lymnaea and the isolation of an endogenous ligand. This peptide, PSFHSWSamide, belongs to the leucokinin family of peptides, and, thus, this Lymnaea receptor is the first example of a leucokinin-like neuropeptide receptor, representing a new subfamily of G-protein-coupled neuropeptide receptors.

Amino Acid Sequence↗
PubMed1998

Multi-messenger innervation of the male sexual system of Lymnaea stagnalis.

The male copulation behaviour of the hermaphrodite pond snail Lymnaea stagnalis is under the control of five groups of central neurons that produce a variety of neuropeptides and a classical transmitter, 5-hydroxy tryptamine (5HT). In this article, we describe how the male sexual organs of this snail are innervated by axons from these central neurons. We carried out immunocytochemistry with antisera against the tetra peptide Ala-Pro-Gly-TRP-NH2 (APGWamide), the Lymnaea form of neuropeptide tyrosine (LNPY), conopressin, pedal peptide, the FRMFamide copeptide SEEPLY, the GDPFLRFamide co-peptide DEILSR, myomodulin, Lymnaea inhibitory peptide, and 5HT on tissue sections of the following male sexual organs that receive input from the penis nerve: the prostate gland, vas deferens, preputium, and penis. The results demonstrate that the axons of the separate muscle systems contain particular combinations of transmitters. In addition, two networks of peripheral neurons were revealed. In the tip of the everted preputium lies what appears to be a network of conopressin-containing sensory neurons, which is possibly involved in probing; probing is the part of copulation behaviour in which the male searches for the female genital pore. The other network of peripheral neurons surrounds the most proximal part of the vas deferens and is most likely involved in the pacemaker control of vas deferens motility. On the basis of the data obtained, we hypothesize how the preputium and penis are everted during copulation and which transmitters and central neurons might be involved.

Animals↗
PubMed1998

Transmitter identification in neurons involved in male copulation behavior in Lymnaea stagnalis.

In this paper, we have mapped the cellular localization of various transmitters onto the central neurons which are involved in male copulation behavior in Lymnaea stagnalis, by combining retrograde tracing with immunocytochemistry and in situ hybridization. Evidence is provided that neurons which were backfilled from the penis nerve, the sole nerve to innervate the male copulatory organ, synthesize a multitude of neuropeptides (APGWamide, Lymnaea neuropeptide tyrosin [LNPY], conopressin, pedal peptide, SEEPLY, DEILSR, myomodulin, and Lymnaea inhibitory peptide [LIP]) as well as the classical neurotransmitter, serotonin. In the anterior lobe, the backfilled neurons mainly contain the tetrapeptide APGWamide and conopressin, and not LNPY or pedal peptide. The results suggest a central role in the regulation of copulation activity for the anterior lobe neurons that produce APGWamide and conopressin. Immunostainings of backfilled nervous systems revealed immunopositive axons originating from these neurons to form varicosities on the cell somata of neurons in the other clusters contributing to the innervation of the male sexual system. Neurons from the right parietal ganglion projecting into the penis nerve were electrophysiologically and morphologically identified by simultaneously recording from the cell body intracellularly and the penis nerve extracellularly and subsequently filling them with an anterograde tracer and subjecting them to immunocytochemistry. This method has provided links between morphology, physiology, and the transmitter contents of these neurons.

Animals↗