Search results for "Lymnaea"
showing 10 items of 54 documents
Fascioliasis transmission by Lymnaea neotropica confirmed by nuclear rDNA and mtDNA sequencing in Argentina
2009
Fascioliasis is widespread in livestock in Argentina. Among activities included in a long-term initiative to ascertain which are the fascioliasis areas of most concern, studies were performed in a recreational farm, including liver fluke infection in different domestic animal species, classification of the lymnaeid vector and verification of natural transmission of fascioliasis by identification of the intramolluscan trematode larval stages found in naturally infected snails. The high prevalences in the domestic animals appeared related to only one lymnaeid species present. Lymnaeid and trematode classification was verified by means of nuclear ribosomal DNA and mitochondrial DNA marker sequ…
DNA sequence characterisation and phylogeography of Lymnaea cousini and related species, vectors of fascioliasis in northern Andean countries, with d…
2011
Abstract Background Livestock fascioliasis is a problem throughout Ecuador, Colombia and Venezuela, mainly in Andean areas where the disease also appears to affect humans. Transmission patterns and epidemiological scenarios of liver fluke infection have shown to differ according to the lymnaeid vector snail species involved. These Andean countries present the vectors Lymnaea cousini, L. bogotensis and L. ubaquensis, unknown in the rest of Latin America. An exhaustive combined haplotype study of these species is performed by means of DNA sequencing of the nuclear ribosomal 18S RNA gene, ITS-2 and ITS-1, and mitochondrial DNA cox 1 gene. Results The conserved 5.8S rDNA sequence corroborated t…
Is the population genetic structure of complex life cycle parasites determined by the geographic range of the most motile host?
2010
Due to their particular way of life, dispersal of parasites is often mediated by their host's biology. Dispersal distance is relevant for parasites because high degree of dispersal leads to high gene flow, which counters the rate of parasite local adaptation in the host populations. Parasites with complex life cycles need to exploit sequentially more than one host species to complete their life cycle. Most trematode parasites have such complex life cycles involving invertebrate and vertebrate hosts. The spatial scales of invertebrate and vertebrate host populations are often different, which may decrease the probability that the parasite cycles locally in the intermediate host population. W…
Primers for nine microsatellite loci in the hermaphroditic snailLymnaea stagnalis
2003
Variation in and amplification conditions for nine polymorphic microsatellite loci identified from Lymnaea stagnalis , a hermaphroditic pulmonate snail, are described. Eight populations from central Finland were studied, which varied in terms of both observed polymorphism and heterozygosity. The number of alleles at each locus is moderate (two to seven), except for one exceptional locus having 16 alleles, and for which null alleles are possible. There is no evidence for genotypic disequilibrium in the populations for all pairs of loci. Heterozygosity levels are indicative of outcrossing in L. stagnalis , whose mating system will be characterized further using these markers.
THE EFFECTS OF MATING SYSTEM AND GENETIC VARIABILITY ON SUSCEPTIBILITY TO TREMATODE PARASITES IN A FRESHWATER SNAIL, LYMNAEA STAGNALIS
2004
The amount and distribution of genetic variability in host populations can have significant effects on the outcome of host-parasite interactions. We studied the effect of mating system and genetic variability on susceptibility of Lymnaea stagnalis snails to trematode parasites. Mating system of snails from eight populations differing in the amount of genetic variability was manipulated, and self- and cross-fertilized offspring were exposed to naturally occurring trematode parasites in a controlled lake experiment. Susceptibility of snails varied between populations, but mating-system treatment did not have a significant effect. Heterozygosity of snails was negatively correlated with the pro…
Inbreeding does not alter the response to an experimental heat wave in a freshwater snail
2019
Global climate change affects natural populations of many species by increasing the average temperature and the frequency of extreme weather events (e.g. summer heat waves). The ability of organisms to cope with these environmental changes can, however, depend on their genetic properties. For instance, genetic load owing to inbreeding could alter organisms’ responses to climate change-mediated environmental changes but such effects are often overlooked. We investigated the effects of an experimental heat wave (25°C versus 15°C) on life history (reproduction, size) and constitutive immune defence traits (phenoloxidase-like and antibacterial activity of haemolymph) in relation to inbreeding b…
Survival and infectivity of Hypoderaeum conoideum and Euparyphium albuferensis cercariae under laboratory conditions.
1999
The survival characteristics of the cercariae of Hypoderaeumconoideum and Euparyphiumalbuferensis (Trematoda: Echinostomatidae) at 20°C and 30°C are described, and the age dependency of their infectivity at 20°C is studied to determine their respective transmission efficiencies. Cercarial survival was found to be age-dependent and was higher at 20°C. For both cercariae, the maximum life-span was 26 h at 20°C and 16 h at 30°C, and their respective times to 50% mortality were similar at each temperature. Both cercariae seem to be well adapted to transmission in their natural habitat, though cercarial infectivity of H. conoideum was higher than that of E. albuferensis, this being correlated wi…
Echinostoma friedi: the effect of age of adult worms on the infectivity of miracidia.
2004
AbstractThe effect of ageing of adults ofEchinostoma friedi(Trematoda: Echinostomatidae) on the infectivity of miracidia yielded was analysed. Miracidia were obtained after hatching of eggs obtained from adult worms ofE. friedicollected weekly during the course of experimental infections in golden hamsters. Miracidial infectivity, measured in terms of percentage of infection inLymnaea peregra, was significantly influenced by the age of the adult worms from which the miracidia were derived. Infective miracidia only were obtained from adult worms in the age range from 4 to 9 weeks post-infection. Infectivity was maximal in those miracidia derived from adults collected 8 and 9 weeks post-infec…
Quality attracts parasites: host condition‐dependent chemo‐orientation of trematode larvae
2015
Summary Environmental factors impairing physiological condition of organisms are assumed to predispose them to parasite infections. This is because host immune function is typically condition-dependent. However, poor physiological condition has been reported to reduce host susceptibility to parasites in various systems. We examined whether such an effect can be due to altered exposure of hosts to active parasite transmission stages by investigating chemo-orientation of free-swimming cercariae larvae of a parasite Echinoparyphium aconiatum towards its snail host Lymnaea stagnalis. We used both long-term and short-term feeding treatments to manipulate the body condition and physiological trai…
Human fascioliasis endemic areas in Argentina: multigene characterisation of the lymnaeid vectors and climatic-environmental assessment of the transm…
2016
Background: In South America, fascioliasis stands out due to the human endemic areas in many countries. In Argentina, human endemic areas have recently been detected. Lymnaeid vectors were studied in two human endemic localities of Catamarca province: Locality A beside Taton and Rio Grande villages; Locality B close to Recreo town. Methods: Lymnaeids were characterised by the complete sequences of rDNA ITS-2 and ITS-1 and fragments of the mtDNA 16S and cox1. Shell morphometry was studied with the aid of a computer image analysis system. Climate analyses were made by nearest neighbour interpolation from FAO data. Koeppen & Budyko climate classifications were used. De Martonne aridity index a…