Distribution and Ultrastructure of Epidermal Sensory Cells in the Freshwater Snails Lymnaea Stagnalis and Biomphalaria Pfeifferi

1971 ◽  
Vol 22 (3) ◽  
pp. 283-298 ◽  
Author(s):  
U. Zylstra
Keyword(s):  
Lymnaea Stagnalis ◽  
Sensory Cells ◽  
Freshwater Snails ◽  
Biomphalaria Pfeifferi

scholarly journals Analysis of the type material of Gomphosphenia tackei (Bacillariophyceae) and comparison to epizoic diatom populations on freshwater snails

2021 ◽  
Vol 154 (2) ◽  
pp. 257-263
Author(s):  
Mateusz Rybak ◽  
Łukasz Peszek ◽  
Anita Poradowska
Keyword(s):  
Electron Microscopy ◽  
Lymnaea Stagnalis ◽  
Morphological Characteristics ◽  
Small Cell ◽  
Type Material ◽  
Freshwater Snails ◽  
Sem Images ◽  
Small Cell Size ◽  
Type Population ◽  
Scanning Electron

Background and aims – Hustedt (1942) originally described Gomphosphenia tackei from Germany under the name Gomphonema tackei. Because of the small cell size and the lack of scanning electron microscopy (SEM) images from the type material, it is often confused with other species from this genus, especially with G. stoermeri. The aim of this paper was to present detailed morphological characteristics of G. tackei based on the analysis of the type material and of several epizoic populations from Central Europe. Material and methods – The material in this study was collected from the shells of the freshwater snails Lymnaea stagnalis, Planorbarius corneus, and Planorbis planorbis. Additionally, for an unambiguous species identification, the type material for Gomphosphenia tackei was analyzed using light and scanning electron microscopes.Key results – The presence of Gomphosphenia tackei was confirmed in the studied material. The largest population (up to 19%) was recorded on the shell surfaces of living snails, whereas on empty shells, the diatom did not seem to be present or only in very low numbers. Valves are typically clavate with rounded apices. Valves are frequently observed in girdle view, often joint together in pairs. The valves in the studied populations had a valve length of 7–29 µm, a valve width of 3–4 µm, and a stria density of 25–29 striae in 10 µm. In the type population, valve length ranged from 7.5 to 27 µm with a valve width of 3.0–4.0 µm and a stria density of 23–29 striae per 10 µm. Striae were composed of 2–4 elongated to rounded areolae per stria. At the apices, the striae were composed of one single areola. The cells were attached to the substratum by their footpole.Conclusion – Published illustrations of Gomphosphenia tackei do not always correctly represent this species. Individual cells are attached to the substratum by secreted mucilage, probably via their areolae or girdle band pores located on the footpole.

scholarly journals Furcocercous cercariae (Trematoda) from freshwater snails in Central Finland

2007 ◽  
Vol 52 (4) ◽  
Author(s):  
Anna Faltýnková ◽  
Katarzyna Niewiadomska ◽  
Maria Santos ◽  
E. Valtonen
Keyword(s):  
New Species ◽  
Lymnaea Stagnalis ◽  
Host Record ◽  
Freshwater Snails ◽  
Snail Species ◽  
Planorbarius Corneus ◽  
Larval Stages ◽  
Diplostomum Pseudospathaceum

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%) and Diplostomum pseudospathaceum Niewiadomska, 1984 (10.0%). Our study represents the first host record of Valvata macrostoma for larval stages of Australapatemon sp. and Sanguinicola sp.

The occurrence of schistosomin, an antagonist of female gonadotropic hormones, is a general phenomenon in haemolymph of schistosome-infected freshwater snails

Parasitology ◽  
1991 ◽  
Vol 103 (3) ◽  
pp. 371-378 ◽  
Author(s):  
M. De Jong-Brink ◽  
M. Elsaadany ◽  
M. S. Soto
Keyword(s):  
Lymnaea Stagnalis ◽  
Digenetic Trematode ◽  
Freshwater Snails ◽  
Snail Species ◽  
General Phenomenon ◽  
Bulinus Truncatus ◽  
Diplostomum Spathaceum ◽  
Target Organs ◽  
Trichobilharzia Ocellata ◽  
Gonadotropic Hormones

In haemolymph of Lymnaea stagnalis, parasitized with the digenetic trematode parasite Trichobilharzia ocellata, a neuropeptide (schistosomin) occurs which antagonizes female gonadotropic hormones, e.g. calfluxin (CaFl). By means of an ultracytochemical hormone-assay, the CaFl assay, it was demonstrated that the occurrence of schistosomin is a general phenomenon in schistosome-infected freshwater snails. Haemolymph of the schistosomiasis-transmitting snail species Biomphalaria glabrata and B. pfeifferi, parasitized with Schistosoma mansoni, also appeared to contain an antagonizing factor, i.e. schistosomin. In contrast, in haemolymph of L. stagnalis parasitized with Diplostomum spathaceum (Diplostomatidae) no schistosomin could be found. This suggests that schistosomin may only occur in snails infected with parasites belonging to the Schistosomatidae. The effect of schistosomin is rather specific. Haemolymph of B. glabrata parasitized with S. mansoni had not the capacity to inhibit the response to CaFl in the target organs for CaFl, the albumen glands of L. stagnalis and Bulinus truncatus. The same holds true for haemolymph of infected L. stagnalis: it did not inhibit the CaFl response in glands of B. glabrata and B. truncatus and even not in those of a related species (L. ovata). Schistosomins in haemolymph of infected B. glabrata and B. pfeifferi, on the other hand, seem more related. Both appeared to inhibit the hormone response in glands of the two Biomphalaria species studied. The results indicate that schistosomin in haemolymph of schistosome-infected pulmonate snails, although functionally related, may differ structurally.

scholarly journals MALDI-TOF mass spectrometry for the identification of freshwater snails from Senegal, including intermediate hosts of schistosomes

2021 ◽  
Vol 15 (9) ◽  
pp. e0009725
Author(s):  
Fatima Zohra Hamlili ◽  
Fatou Thiam ◽  
Maureen Laroche ◽  
Adama Zan Diarra ◽  
Souleymane Doucouré ◽  
...  
Keyword(s):  
Neglected Diseases ◽  
Freshwater Snails ◽  
Snail Species ◽  
Correct Identification ◽  
Intermediate Hosts ◽  
Biomphalaria Pfeifferi ◽  
Bulinus Truncatus ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

Freshwater snails of the genera Biomphalaria, Bulinus, and Oncomelania are intermediate hosts of schistosomes that cause human schistosomiasis, one of the most significant infectious neglected diseases in the world. Identification of freshwater snails is usually based on morphology and, potentially, DNA-based methods, but these have many drawbacks that hamper their use. MALDI-TOF MS has revolutionised clinical microbiology and has emerged in the medical entomology field. This study aims to evaluate MALDI-TOF MS profiling for the identification of both frozen and ethanol-stored snail species using protein extracts from different body parts. A total of 530 field specimens belonging to nine species (Biomphalaria pfeifferi, Bulinus forskalii, Bulinus senegalensis, Bulinus truncatus, Bulinus globosus, Bellamya unicolor, Cleopatra bulimoides, Lymnaea natalensis, Melanoides tuberculata) and 89 laboratory-reared specimens, including three species (Bi. pfeifferi, Bu. forskalii, Bu. truncatus) were used for this study. For frozen snails, the feet of 127 field and 74 laboratory-reared specimens were used to validate the optimised MALDI-TOF MS protocol. The spectral analysis yielded intra-species reproducibility and inter-species specificity which resulted in the correct identification of all the specimens in blind queries, with log-score values greater than 1.7. In a second step, we demonstrated that MALDI-TOF MS could also be used to identify ethanol-stored snails using proteins extracted from the foot using a specific database including a large number of ethanol preserved specimens. This study shows for the first time that MALDI-TOF MS is a reliable tool for the rapid identification of frozen and ethanol-stored freshwater snails without any malacological expertise.

scholarly journals Environmental determinants of distribution of freshwater snails and trematode infection in the Omo Gibe River Basin, southwest Ethiopia

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Seid Tiku Mereta ◽  
Jemal Bedewi ◽  
Delenasaw Yewhalaw ◽  
Belayhun Mandefro ◽  
Yihun Abdie ◽  
...  
Keyword(s):  
Open Field ◽  
Human Activities ◽  
Livestock Grazing ◽  
Freshwater Snails ◽  
Infection Rates ◽  
Biomphalaria Pfeifferi ◽  
Water Contact ◽  
Southwest Ethiopia ◽  
Trematode Infection ◽  
Open Field Defecation

Abstract Background Determination of infection rates of snail populations is one of the basic tools for epidemiological studies of snail borne diseases. In this study, we opted to determine the trematode infection of freshwater snails in the Omo-Gibe River Basin, southwest Ethiopia. Methods We collected snail samples from 130 observation sites in lakes, wetlands, rivers, reservoirs and irrigation canals surveyed during the dry season (March to May) in 2016. The snail samples were examined for trematode infections by cercarial shedding immediately after collection. Habitat conditions, water quality, human water contact practices and other human activities were assessed at each survey site. A redundancy analysis (RDA) was used to examine the relationship between cercarial infection and environmental variables. The statistical significance of eigenvalues and cercariae-environment correlations generated by the RDA were tested using Monte Carlo permutations at 499 permutations. Results A total of 3107 snails belonging to five species were collected. The most abundant species was Biomphalaria pfeifferi, representing 66% of the total collection. Overall, 109 (3.6%) of the snails were found infected with trematodes (cercariae). Biomphalaria pfeifferi was found to be the most highly infected, accounting 85% of all infected snails. A total of eight morphologically different types of cercariae were recorded, which included: Echinostoma cercariae, brevifurcate apharyngeate distome cercariae, amphistome cercariae, brevifurcate apharyngeate monostome cercariae, xiphidiocercariae, longifurcate pharyngeate distome cercariae, strigea cercariae and unidentified cercariae. Brevifurcate apharyngeate distome cercariae, and Echinostoma cercariae were the most abundant cercariae, accounting for 36 and 34% of all infection, respectively. The mean concentration of water conductivity and 5 days biological oxygen demand were higher in irrigation canals and lake sampling points. Human activities such as open field defecation, urination, livestock grazing, farming, and swimming were highly correlated with trematode infection. Conclusions The abundance, occurrence and infection rates of snail species were largely influenced by water physicochemical quality, sanitation and water contact behaviour of the inhabitants. Human activities, such as open field defecation and urination, livestock grazing, farming, and swimming were important predictors of the abundance of cercariae. Therefore, awareness creation should be implemented for proper containment of excreta (urine and faeces) and reducing human and animal contacts with surface waters to reduce snail-borne disease transmission.

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