Search results for "Prosobranchia"
showing 6 items of 6 documents
A male XO sex-determining mechanism in Theodoxus meridionalis (Neritidae) (Prosobranchia, Archaeogastropoda).
1988
The haploid number of chromosomes n=12+h and the diploid values 2n=25 in males, and 2n=26 in females, have been determined for three geographically separated populations of Theodoxus meridionalis (Neritidae). A male XO sex-determining mechanism has been observed for this species.
Furcocercous cercariae (Trematoda) from freshwater snails in Central Finland
2007
AbstractA total of eight species of furcocercous cercariae of four families (Strigeidae, Diplostomidae, Schistosomatidae and Sanguinicolidae), were found in 2005 in Lake Konnevesi in Central Finland in four snail species (Valvata macrostoma, Lymnaea stagnalis, Bathyomphalus contortus and Planorbarius corneus). Australapatemon burti (Miller, 1923), Australapatemon sp., Cotylurus brevis Dubois et Rausch, 1950, Cercaria spinulosa Ginetsinskaya, 1959 and Sanguinicola sp. are new species records for Finland. Ichthyocotylurus variegatus (Creplin, 1825) and Bilharziella polonica (Kowalewski, 1895) were first recorded as cercariae in Finland. The most common cercariae were A. burti (prevalence 13.3…
Spermiogenesis in the vermetid gastropod Dendropoma petraeum (Gastropoda, Prosobranchia)
2002
The structure and maturation of the male gonad of the Mediterranean vermetid gastropod Dendropoma petraeum are described. Histological sections of the gonads were made throughout development and gonad activity was monitored at regular monthly intervals. During the autumn months the gonad is very small and is surrounded by a large quantity of connective tissue; it becomes more voluminous from December to August, with the highest growth peak in springtime. The stages of spermatogenesis were also observed and described.
Spermatocyte chromosome banding studies inBuccinulum corneum (Prosobranchia: Neogastropoda): Variation in silver-NOR banding pattern
1990
Diploid number (2n=72), and haploid number (n=36) forBuccinulum corneum (L. 1758) collected from the Gulf of Palermo in December 1987 were determined. A simple method to obtain nucleolar organizer regions (NOR), and constitutive heterochromatin regions (C-bands) of chromosomes ofB. corneum is described. Analyses of silver-stained chromosome preparations ofB. corneum suggest that a within-individual variability in NOR-banding pattern is present in each of the five specimens analysed.
Spatial and temporal structure of the trematode component community inValvata macrostoma(Gastropoda, Prosobranchia)
2008
SUMMARYWe conducted the first comprehensive study on the spatiotemporal structure of trematode communities in the large-mouthed valve snail,Valvata macrostoma. A total of 1103 snails were examined monthly between May and October 2007 from Lake Konnevesi, Central Finland, from a shallow (1–2 m deep) and an offshore site (5–6 m deep), located ca. 50–70 m apart. Snails were infected by 10 trematode species. The species composition and prevalence were strikingly different between the sites with high species diversity in the shallow site (all 10 species; total prevalence of sporocysts/rediae 12·1%, metacercariae 55·4%) compared to the deeper site (3 species; prevalence 15·0% and 1·9%, respective…
FISH mapping of 18S-28S and 5S ribosomal DNA, (GATA)n and (TTAGGG)n telomeric repeats in the periwinkle Melarhaphe neritoides (Prosobranchia, Gastrop…
2001
Spermatocyte chromosomes of Melarhaphe neritoides (Mollusca, Prosobranchia, Caenogastropoda) were studied using fluorescent in situ hybridization (FISH) with four repetitive DNA probes (18S rDNA, 5S rDNA, (TTAGGG)n and (GATA)n). Single-colour FISH consistently mapped one chromosome pair per spread using either 18S or 5S rDNA as probes. The telomeric sequence (TTAGGG)n hybridized with termini of all chromosomes whereas the (GATA)n probe did not label any areas. Simultaneous 18S-5S rDNA and 18S-(TTAGGG)n FISH demonstrated that repeated units of the three multicopy families are closely associated on the same chromosome pair.