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David Rollinson - One of the best experts on this subject based on the ideXlab platform.

  • A molecular phylogenetic analysis of Bulinus (Gastropoda: Planorbidae) with conserved nuclear genes
    Zoologica Scripta, 2010
    Co-Authors: Aslak Jørgensen, J. Russell Stothard, David Rollinson, Henry Madsen, Allen Nalugwa, Silvester Nyakaana, Thomas K. Kristensen
    Abstract:

    Jorgensen, A., Madsen, H., Nalugwa, A., Nyakaana, S., Rollinson, D., Stothard, J. R. & Kristensen, T. K. A molecular phylogenetic analysis of Bulinus (Gastropoda: Planorbidae) with conserved nuclear genes. —Zoologica Scripta, 40, 126–136. Mutational saturation of inspected DNA loci and topological incongruence in the phylogenetic inferences have previously confounded attempts to resolve the evolutionary relationships within the freshwater snail genus Bulinus. Traditionally, the 37 species of Bulinus are placed within the four species groups and the evolutionary divergence between groups is substantial. With an intention to shed new light on species group relationships, the present study was designed to investigate the basal divergences in the phylogeny of Bulinus using highly conserved nuclear genes. The resolved phylogeny inferred that the four species groups of Bulinus were monophyletic and Shimodaira-Hasegawa topology tests found them to be significantly supported. The Bulinus truncatus/tropicus species complex and Bulinus wrighti (Bulinus reticulatus group) formed a well-supported sister-group relationship. The Bulinus africanus species group was the sister-group to the clade (Bulinus truncatus/tropicus + B. wrighti) with the Bulinus forskalii species group as the sister-group to these taxa. The sister-group relationship between Indoplanorbis and Bulinus was non-significant and the basal clade support of Bulinus improved upon exclusion of Indoplanorbis. The finding of basal long branches of Bulinus species originating from Madagascar strongly suggests the presence of additional cryptic species and an evolutionary scenario influenced by this island’s geological vicariance from the African mainland. Speciation by polyploidy was inferred to have evolved within a clade in the Bulinus truncatus/tropicus species complex. Although the monophyletic status of each species group was firmly supported, it was difficult to establish species group concepts equally across the variations and place this precisely in a specific temporal framework.

  • Microsatellites in the freshwater snail Bulinus globosus (Gastropoda: Planorbidae) from Zanzibar
    Molecular Ecology Notes, 2003
    Co-Authors: Aidan M. Emery, Nicola J. Loxton, J. Russell Stothard, Catherine S. Jones, Jenny Spinks, Julia Llewellyn-hughes, Leslie R. Noble, David Rollinson
    Abstract:

    Six microsatellite loci were isolated and characterized in Bulinus globosus, a freshwater snail with a wide distribution throughout sub-Saharan Africa. Bulinus globosus is an intermediate host of Schistosoma haematobium, the causative agent of human urinary schistosomiasis. Microsatellites were tested using 32 snails from four populations collected from Pemba and Unguja islands of Zanzibar. The microsatellite loci displayed relatively low levels of variation, with between two and five alleles per locus. FST estimates indicate that gene flow is low, as has previously been suggested for other species of Bulinus.

  • freshwater snails on mafia island tanzania with special emphasis upon the genus bulinus gastropoda Planorbidae
    Journal of Zoology, 2002
    Co-Authors: Russell J Stothard, Nicola J. Loxton, David Rollinson
    Abstract:

    A survey of freshwater snails on Mafia Island has been conducted that mapped the distribution and, by using a timed searching strategy, documented the relative levels of abundance of species. Twenty-five freshwater habitats around the island were surveyed; snails were found in 15 sites (60%). From the total number of snails collected (n=240), prosobranchs (59%) outnumbered pulmonates (41%). Potential intermediate hosts of urinary schistosomiasis were encountered and these Bulinus species were further characterized by analysis of six enzyme systems (GPI, PGM, MDH, HBDH, GDH & AcP), by inspection of DNA sequence variation within mitochondrial cytochrome oxidase sub-unit I (COI) and nuclear ribosomal internal transcribed spacer (ITS). Three species of Bulinus were found: a single B. africanus group taxon, B. nasutus, and two B. forskalii group taxa, B. forskalii and a species presently identified as Bulinus sp. in this paper. The genera Pila, Lanistes and Bulinus were widespread across the island and dominated the fauna. The remaining taxa were found in lower numbers and often only at single sites. Three prosobranchs: Lanistes purpureus, Pila ovata and Melanoides tuberculata were found. In addition to Bulinus, the pulmonates included a small discoidal planorbid (?)Ceratophallus and an ancylid (a freshwater limpet). The factors that shape the dispersal and distribution of molluscs on Mafia were considered. Water chemistry could be an important variable as both pH (mean 6.37±0.99 SD) and conductivity (mean μS=149±135 SD) were significantly different from similar habitats on neighbouring Zanzibar Island (P<0.001). The Mafian fauna is clearly associated with that of mainland Africa and Madagascar.

  • heritability of male outcrossing ability in the simultaneous hermaphrodite bulinus truncatus gastropoda Planorbidae
    Journal of Zoology, 1992
    Co-Authors: Stephanie J Schrag, David Rollinson, A E Keymer, Andrew F Read
    Abstract:

    The heritability of phally, a dichotomous trait defined by the functional state of the male reproductive tract, was measured in a laboratory population of the simultaneous hermaphrodite snail Bulinus truncatus by means of a breeding experiment and a selection experiment. Euphallic individuals develop a fully functional male and female tract and are capable of receiving and donating sperm. In aphallic individuals the male tract does not develop fully, preventing sperm donation. There was no evidence of a heritable component to phally in the breeding experiment, but the selection experiment demonstrated a slight heritable effect. In both experiments there was more variation in the observed proportion of euphallics than expected by chance alone and no evidence of line or family effects, implicating environmental determination of male outcrossing ability even under controlled laboratory conditions. Previous studies of populations of B. truncatus reported that the proportion of euphallics was under strong genetic control. We suggest that there may be population differences in the extent of environmental control over phally, analogous to that reported for sex determination.

Omar Dos Santos Carvalho - One of the best experts on this subject based on the ideXlab platform.

  • biomphalaria molluscs gastropoda Planorbidae in rio grande do sul brazil
    Memorias Do Instituto Oswaldo Cruz, 2009
    Co-Authors: Michele Soares Pepe, Roberta Lima Caldeira, Omar Dos Santos Carvalho, Gertrud Muller, Liana K Jannottipassos, Alice Pozza Rodrigues, Hugo Leonardo Da Cunha Amaral, Maria Elisabeth Aires Berne
    Abstract:

    The present study was aimed at characterising Biomphalaria species using both morphological and molecular (PCR-RFLP) approaches. The specimens were collected in 15 localities in 12 municipalities of the southern region of the state of Rio Grande do Sul, Brazil. The following species were found and identified: Biomphalaria tenagophila guaibensis, Biomphalaria oligoza and Biomphalaria peregrina. Specimens of the latter species were experimentally challenged with the LE Schistosoma mansoni strain, which showed to be refractory to infection.

  • phylogenetics of south american biomphalaria and description of a new species gastropoda Planorbidae
    Journal of Molluscan Studies, 2006
    Co-Authors: Roberta Lima Caldeira, Victoria Estrada, Luz Elena Velasquez, Eduar Elias Bejarano, Winston Rojas, Omar Dos Santos Carvalho
    Abstract:

    The planorbid snail Biomphalaria edisoni n. sp. is described from morphological and molecular characters, based on specimens collected at two localities in Colombia. The new species has the typical features of the genus, as well as the following characteristics: vaginal pouch, numerous prostatic diverticula arranged in racemes, penis sheath/prepuce ratio of approximately 2 and a penial complex half the length of the cephalic portion of the female duct. These elements differentiate it from B. kuhniana, which was also present in one of the localities, and also from B. prona, B. helophila and B. nicaraguana, with which it has greater morphological similarities. Phylogenetic analysis of the nucleotide sequences of the internal spacers of the ribosomal DNA transcript (ITS1, ITS2) of B. edisoni n. sp. and 14 neotropical Biomphalaria species indicates that the former belongs to the monophyletic group including B. prona and B. sp. from Cuba. The genetic distances within this monophyletic group are however great enough for B. edisoni n. sp. to be regarded as a separate species. Thus morphology, phylogenetic tree topology and genetic distances all support the recognition of B. edisoni as a new species.

  • genetic variability and molecular identification of brazilian biomphalaria species mollusca Planorbidae
    Parasitology, 2001
    Co-Authors: Omar Dos Santos Carvalho, Roberta Lima Caldeira, A J G Simpson, Teofânia H D A Vidigal
    Abstract:

    Freshwater snails belonging to the genus Biomphalaria are intermediate hosts of the trematode Schistosoma mansoni in the Neotropical region and Africa. In Brazil, one subspecies and ten species of Biomphalaria have been identified: B. glabrata, B. tenagophila, B. straminea, B. occidentalis, B. peregrina, B. kuhniana, B. schrammi, B. amazonica, B. oligoza, B. intermedia and B.t. guaibensis. However, only the first three species are found naturally infected with S. mansoni. The classical identification of these planorbids is based on comparison of morphological characteristics of the shell and male and female reproductive organs, which is greatly complicated by the extensive intra-specific variation. Several molecular techniques have been used in studies on the identification, genetic structure as well as phylogenetic relationships between these groups of organisms. Using the randomly amplified polymorphic DNAs (RAPD) analysis we demonstrated that B. glabrata exhibits a remarkable degree of intra-specific polymorphism. Thus, the genetics of the snail host may be more important to the epidemiology of schistosomiasis than those of the parasite itself. Using the simple sequence repeat anchored polymerase chain reaction (SSR-PCR) in intra-populational and intra-specific studies we have demonstrated that snails belonging to the B. straminea complex (B. straminea, B. kuhniana and B. intermedia) clearly presented higher heterogeneity. Using the low stringency polymerase chain reaction (LS-PCR) technique we were able to separate B. glabrata from B. tenagophila and B. tenagophila from B. occidentalis. To separate all Brazilian Biomphalaria species we used the restriction fragment length polymorphism (PCR-RFLP) of the internal transcribed spacer region (ITS) of the DNA gene. The method also proved to be efficient for the specific identification of DNA extracted from snail eggs. Recently we have sequenced the ITS2 region for phylogenetic studies of all Biomphalaria snails from Brazil.

M E J Woolhouse - One of the best experts on this subject based on the ideXlab platform.

  • impact of geographical origin on mating behaviour in two species of biomphalaria Planorbidae gastropoda
    Animal Behaviour, 1999
    Co-Authors: J C Rupp, M E J Woolhouse
    Abstract:

    Abstract Studies of inbreeding and outcrossing have traditionally concentrated on matings within populations. The influence of geographical origin on mate choice in animals from different populations has received less attention. We investigated whether planorbid snails mated preferentially within their own population or with snails from other populations. Snails from three Biomphalaria pfeifferi strains and three B. glabrata strains were allowed to mate with conspecifics in the laboratory. We recorded their matings at night using time-lapse video. When they could choose between sympatric and allopatric snails, Biomphalaria snails significantly preferred the former: snails of each population mated more often with sympatric than with allopatric snails. This tendency to avoid outcrossing may indicate that, in some species, local adaptations can be more valuable than genetic novelties.

Margaret Mulvey - One of the best experts on this subject based on the ideXlab platform.

  • neotropical schistosomiasis african affinities of the host snail biomphalaria glabrata gastropoda Planorbidae
    Biological Journal of The Linnean Society, 1997
    Co-Authors: David S Woodruff, Margaret Mulvey
    Abstract:

    Schistosoma mansoni, the blood fluke responsible for human intestinal schistosomiasis in the Neotropics, was imported repeatedly with African slaves during the period 1500–1800. This trematode, and its intermediate host snails of the genusBiomphalaria, are widely distributed across Africa and the disease is thought to have quickly become established in South America and the West Indies because of the presence of an endemic susceptible congener,B. glabrata. We comparedB. glabratawith four other Neotropical and three African species ofBiomphalariausing 20 allozyme loci and found that it is phenetically and phylogenetically more like the African species; both parasite and American host snail are apparently of historically or geologically recent African origin. Furthermore, genetic distances, cladistic analyses and fossil data suggest the AfricanBiomphalariaspecies may themselves have evolved from Neotropical founders following an initial trans-Atlantic dispersal in the reverse direction 2.3–4.5 Mya. Interpretation of existing patterns remains problematic as few African snails have been characterized genetically and bothB. glabrataand AfricanB. pfeifferiappear to comprise several cryptic species.

J G Esteban - One of the best experts on this subject based on the ideXlab platform.

  • infectivity of echinostoma friedi miracidia to different snail species under experimental conditions
    Journal of Helminthology, 2006
    Co-Authors: Carla Munozantoli, Rafael Toledo, Maria Trelis, J G Esteban
    Abstract:

    The infectivity of Echinostoma friedi (Trematoda: Echinostomatidae) miracidia was studied experimentally in a range of laboratory-reared snails that coexist in the same natural locality, namely Radix peregra, Lymnaea fuscus, L. truncatula (Lymnaeidae), Gyraulus chinensis, Helisoma duryi (Planorbidae) and Physella acuta (Physidae), and snails from different geographical origins acting naturally or experimentally as intermediate hosts of Schistosoma spp., namely Planorbarius metidjensis (from Malaga, Spain), Biomphalaria glabrata (Guadeloupe), B. alexandrina (Egypt) (Planorbidae), Bulinus cernicus (Mauritius), B. globosus (Zambia), B. natalensis (South Africa) and B. truncatus (Niger) (Bulinidae). Six species of snails were found to be susceptible, with the rate of infection ranging from 0 to 36.7%. The highest infection was detected in R. peregra. The low host specificity of E. friedi might have an epidemiological significance as a requisite for a recent establishment in a new geographical area.

  • The life-cycle of Echinostoma friedi n. sp. (Trematoda: Echinostomatidae) in Spain and a discussion on the relationships within the `revolutum' group based on cercarial chaetotaxy
    Systematic Parasitology, 2000
    Co-Authors: R. Toledo, Carla Muñoz-antoli, J G Esteban
    Abstract:

    The morphology of the different stages and life-cycle of Echinostoma friedi n. sp. are described and figured. The freshwater snail Lymnaea peregra (Gastropoda: Lymnaeidae) serves as the natural and experimental first intermediate host and L . corvus and Gyraulus chinensis (Gastropoda: Planorbidae) as experimental first intermediate hosts. These, and Physella acuta (Gastropoda: Physidae), also serve as second intermediate hosts. Adult worms, possessing 37 collar spines, were obtained from naturally infected Rattus norvegicus and experimentally from albino rats, golden hamsters and chickens. Mice were not suitable experimental definitive hosts. E . friedi differs from the most closely related species in the ` revolutum ' group mainly in terms of several morphological and biological features of the life-cycle stages and in its cercarial chaetotaxy. The chaetotaxy patterns of the species of the ` revolutum ' group are analyzed and the results show that a taxonomic comparison of these species may be carried out on the basis of the number of sensilla in the clusters CIII V_1, CIII V_2 (or CIII V_1 + CIII V_2), CIV DL and UV_b. These clusters appear adequate to establish taxonomic relationships between different species within the ` revolutum ' group.

  • Cercarial chaetotaxy of Euparyphium albuferensis Esteban et al., 1997 (Trematoda: Echinostomatidae), with a review of some genera of the Echinostomatinae
    Systematic Parasitology, 1998
    Co-Authors: R. Toledo, Carla Muñoz-antoli, L. Sánchez, Ch. Bayssade-dufour, J G Esteban
    Abstract:

    Euparyphium albuferensis Esteban et al., 1997 (Trematoda: Echinostomatidae) is a parasite of the mollusc Gyraulus chinensis (D.) (Gastropoda: Planorbidae) and the mammals Rattus spp. in a nature park near Valencia, Spain. In the present work, the cercarial chaetotaxy is fully determined for specimens emitted by naturally infected G. chinensis. Of particular importance are the following sensillary arrangements: 5 CIV DL, 3 CIV CIV D at the dorso-cephalic level and 0 UV and 22–26 UD in the tail. Evidence is presented to the effect that these sensillary clusters are characteristic of the genus Euparyphium and allow an easy diagnosis, unlike in the case of the adult worms where there are sometimes few or no differences between Echinoparyphium and Echinostoma. A table synthesises the main data on the cercarial sensilla of Euparyphium spp. and the closely related genera Echinoparyphium, Echinostoma, Hypoderaeum, Moliniella, Neoacanthoparyphium, Paryphostomum and Isthmiophora. This shows clear variations in their respective numbers, from 3–5 in CIV DL, 2–4 in CIV D, 0–15 in UV and 19 to 57 in UD, according to the genus. These clusters appear adequate to identify, at the cercarial stage, the principal genera of the Echinostomatinae.

  • life cycle of euparyphium albuferensis n sp trematoda echinostomatidae from rats in spain
    Systematic Parasitology, 1997
    Co-Authors: J G Esteban, Rafael Toledo, L. Sánchez, Carla Munozantoli
    Abstract:

    The morphology of the different life-history stages and life-cycle of Euparyphium albuferensis are described and drawn. The freshwater snail Gyraulus chinensis (Gastropoda: Planorbidae) serves as the natural and experimental first intermediate host. This and other freshwater snails, such as Lymnaea truncatula, L. peregra, L. palustris and Physa acuta, serve as second intermediate hosts. Adult worms, possessing 45 collar spines, were obtained naturally from Rattus norvegicus and R. rattus, and experimentally from albino rats, mice and golden hamsters. Chickens, ducks and pigeons were not suitable experimental definitive hosts. E. albuferensis differs from the most closely related species, E. murinum Tubangui, 1931, in its larger body, suckers and oesophageal measurements, in the distribution of vitelline follicles and in the morphology of the collar spines.