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Sixteen taxa of Gastropoda were found in nine isolated lakes in the Suwalski Landscape Park. The species composition of snails and the number of species were different in individual lakes, but in this group of lakes were similar to those found in the interconnected lakes in this area. Bivalvia were represented by the family Sphaeriidae only.
The excretion of P-PO₄ and N-NH₄ by snails (Lymnaea (Lymnaea) stagnalis, Lymnaea (Radix) auricularia and Planorbarius corneus) was measured in laboratory experiments. For L. (L.) stagnalis the release of these elements from decomposing animals and their faecal material were also determined. Amounts of nutrients excreted by the snails studied varied greatly in the ranges <1 to 70 μg P-PO₄ and <2 to over 200 μg N-NH₄ per individual. These amounts were very much related to the sizes of snails. The phosphorus and nitrogen contained in the tissues of L. (L.) stagnalis are released to the water very rapidly due to the rapid decomposition that the bodies of snails undergo. The release of phosphorus from freshly produced faecal matter is considerable - even greater than the excretion by live snails (expressed per unit weight). However, the limited mass of faeces produced as compared with the body weight of an snail, ensures that this still accounts for only 3% of daily excretion of phosphorus from the body of a live snail.
Hemolymph plasma polypeptides of three pulmonate snail species were analysed by the method of SDS-PAGE followed by Coomassie, silver or Schiff's staining. Polypeptide patterns were also monitored during the course of Fasciola hepatica infection in Galba truncatula and G. palustris. Infection did not result in the induction of specific molecules, but in an augmentation of a few protein fractions, possibly glycoproteins.
To supply more documentary evidence for the effect of parasitic infection on activity of neurosecretory centres in the cerebral ganglia of the snail host, caudo-dorsal and light green cells of adult individuals of Lymnaea stagnalis naturally infected with digenean parthenites were subjected to karyometric analysis. In infected animals significant enlargement of nuclear volumes of both examined types of neurosecretory cells was ascertained. Mean nuclear volume of the light green cells in snails infected with Furcocercariae was significantly lower in comparison with the individuals infected with parthenites from groups Echinostomata and Xiphidiocercariae. In remaining cases differences in nuclear volumes among subpopulations distinguished on the ground of an infection factor were not statistically significant.
Studies upon behariour of snails in anthropogenically changed water environment. 1. Locomotor activity of lymnaea stagnalis (L), with regard to subpopulations infected with developmental stages of digeneans. The aim of the paper was to analyse the locomotor activity of snails, Lymnaea stagnalis, with regard to physico-chemical properties of water in an inhabited reservoir and parasitic infection. The material was collected in selected anthropogenic water environments situated in the Upper Silesian Industrial Region (sinkhole ponds, sand-and clay-excavations). The locomotor activity of each snail was analysed in laboratory conditions by designation of number of penetrated segments, marked in tanks filled with water originating from a given reservoir, during 15', with intervals of l'. It was observed the significant relationship between locomotor activity of examined snails and the water carbonaceous hardness (r = -0,812, at range of the independent variable 173.0-863.5 mg CaCO₃/dm³). Correlation coefficients with other physico-chemical parameters of water were close to zero. Locomotion of snails infected with developmental stages of digenetic trematodes was significantly lower comparing to non-infected individuals. Locomotor activity of these former ones was dependend more on degree of the digestive gland damage by the parasite than on the infection agent.
Total protein and activities of: alpha-amylase, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase in haemolymph of the freshwater snail Lymnaea stagnalis, naturally infected with digenean larvae were investigated. There were no any changes in these parameters in the snails infected with Cercaria tenuispina that occupies mainly haemocoel sinuses. Significant increase of activities of all examined enzymes in haemolymph of the snails infected with larvae belonging to the Furcocercariae group was ascertained. These changes were proportional to the degree of injury of the digestive gland, examined with the use of the thymol turbidity test. Total protein level was significantly higher only in haemolymph of snails with higher values of this test.
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