Biochemical characterization of the putative isoforms of myoglobins from mollusks of the Biomphalaria genus

Although gastropod myoglobin has been extensively studied, there are knowledge gaps in its biological characteristics. We describe for the first time the presence of a myoglobin in the triturative stomach of Biomphalaria gastropods. We compared biochemical parameters of myoglobins of stomach and radular muscles of Biomphalaria glabrata and Biomphalaria tenagophila. Apomyoglobin and holomyoglobin were obtained. Myoglobin was the most abundant protein in the stomach (85.0%) and radular muscles (80.0%) of the two Biomphalaria species evaluated. The Molecular mass and isoeletric point of stomach myoglobins were 16,124.93 Da and 7.98 and 16.095.28 Da and 7.77 for B. glabrata and B. tenagophila, respectively. Stomach myoglobins of B. glabrata and B. tenagophila rate autoxidation were equal to 8.0 × 10⁻⁴ h⁻¹ ± 0.0002 and 1.0 × 10⁻⁴ h⁻¹ ± 0.00142, respectively. Analysis of N-terminal amino acid sequencing revealed that stomach myoglobins are blocked in this region for a chemical group. Concluding, the differences we observed in the biochemical properties of stomach and radular myoglobins of B. glabrata and B. tenagophila suggest they may be isoform representing an evolutionary event related to the adaptation of these proteins.     

Abalone myoglobins evolved from indoleamine dioxygenase: The cDNA-derived amino acid sequence of myoglobin fromNordotis madaka

The cDNA for the unusual 41 kD myoglobin of the abaloneNordotis madaka was amplified by polymerase chain reaction (PCR), and the cDNA-derived amino acid sequence of 378 residues was determined. As with the myoglobin of the related abaloneSulculus diversicolor (Suzuki and Takagi,J. Mol. Biol. 228, 698–700, 1992), the sequence ofNordotis myoglobin showed no significant homology with any other globins, but showed high homology (35% identity) with vertebrate indoleamine 2,3-dioxygenase, a tryptophan degrading enzyme containing heme. The amino acid sequence homology betweenNordotis andSulculus myoglobins was 87%. These results support our previous idea that the abalone myoglobins evolved from a gene for indoleamine dioxygenase, but not from a globin gene, and therefore all of the hemoglobins and myoglobins are not homologous. Thus, abalone myoglobins appear to be a typical case of convergent evolution.     

Morphobiochemical Adaptations to the Littoral Environment in Some Atlantic Gastropods

The morphobiochemical adaptations to the drying and feeding of four species of littoral mollusks collected in a confined area of the Atlantic coast have been analyzed: Tectarius striatus, Siphonaria pectinata, Phorcus atratus, and P. sauciatus. It was established that these mollusks differ strongly from each other morphologically and biochemically, thus demonstrating a variety of adaptations to the same environmental conditions. It was noted that T. striatus is the most adapted to live in the tidal zone. It is assumed that the survival of P. atratus and P. sauciatus in the conditions of drying is to some extent maintained by the green pigment (biliverdin) concentrated in the soft tissues, as its quantity increases as the mollusks remain without water.     

High level of tetracosapolyenoic fatty acids in the cold-water mollusk <Emphasis Type="Italic">Tochuina</Emphasis><Emphasis Type="Italic">tetraquetra</Emphasis> is a result of the nudibranch feeding on soft corals

Fatty acid (FA) markers are used to trace predator–prey relationships in the marine environment. Soft corals contain tetracosapolyenoic acids (TPA), namely 24:5n-6 and 24:6n-3, which are considered as octocoral FA markers. The nudibranch mollusks are known to feed on soft corals. To check whether TPA are transferred from soft corals to nudibranch mollusks during their nutrition, we determined and compared FA compositions of total lipids of Tochuina tetraquetra and soft corals (Acanella sp., Anthomastus rylovi, Gersemia fruticosa, and Paragorgia arborea) collected together near the Kuril Islands (the depths of 80–550 m). FA compositions of T. tetraquetra, Acanella sp. and A. rylovi were described for the first time. In Acanella sp., G. fruticosa, A. rylovi, and P. arborea, the average contents of TPA were 6.5, 13.4, 5.9, and 12.0 % of total FAs, whereas the 24:5n-6/24:6n-3 ratio was 1.0, 1.4, 5.4, and 2.6, respectively. The high level of TPA (21.7 %) found in T. tetraquetra indicates that 24:5n-6 and 24:6n-3 are transferred from soft corals to the mollusks during their feeding and accumulated in mollusk tissues. The most possible feed source of the mollusk is suggested to be G. fruticosa and/or Acanella sp., because the 24:5n-6/24:6n-3 ratios in T. tetraquetra and these soft corals were similar. Thus, the TPA could be used as FA markers to estimate a proportion of soft corals in feeding of cold-water nudibranch mollusks.     

Patterns of individual growth in the field slug <Emphasis Type="Italic">Deroceras agreste</Emphasis> (Gastropoda,Agriolimacidae)

The growth of individual Deroceras agreste slugs from the date of sampling to the end of life has been studied under laboratory conditions. Seven out of 37 mollusks (≈19%) have shown a finite growth pattern, with their body weight reaching a maximum and decreasing thereafter. The data on these mollusks are well approximated by the finite growth equation. Other mollusks have not reached the maximum weight. In many cases, periods of a sharp decrease in body weight with subsequent return to the initial growth curve (compensatory growth) have been observed. In three animals, the growth curve has changed after such a decrease. A comparison of growth parameters in different individuals with the aid of the Ford-Wallford equation has shown that differences between them lack statistical significance. In generally, the slug D. agreste appears to belong to animals with the finite growth pattern.     

Taxonomic composition of bacteria associated with cultivated mollusks <Emphasis Type="Italic">Crassostrea lugubris</Emphasis> and <Emphasis Type="Italic">Perna viridis</Emphasis> and with the water of the Gulf of Nha Trang lagoon,Vietnam

One hundred and four strains of heterotrophic bacteria have been isolated and characterized from two species of bivalve mollusks cultivated in the Gulf of Nha Trang (Vietnam) and from the water of a mariculture farm. The isolates have been identified on the basis of morphological, physiological, biochemical, and chemotaxonomic properties, as well as by the content of G+C bases in DNA. In the microflora of mollusks, Vibrio alginolyticus was predominant; the pathogenic species V. harveyi and V. splendidus were found as well. Staphylococci and bacilli occupied the second place in abundance after vibrios. In addition, coryneforms and enterobacteria, as well as Pseudomonas spp. and Pseudoalteromonas spp., were revealed. The composition of the water microflora was more diverse as compared with the microflora of mollusks. In the water, Bacillus spp., Vibrio spp., and Pseudomonas spp. were predominant. Brevibacterium spp. and other coryneform bacteria, as well as enterobacteria, occurred in significant amounts. In addition, Pseudoalteromonas spp., Marinococcus sp., Halobacillus sp., Shewanella sp., Sulfitobacter sp., and bacteria of the CFB cluster were noticed. The presence of pathogenic and conditionally pathogenic bacterial species in the water and mollusks is probably the reason for the high death rate of cultivated animals at the mariculture farm.     

Feeding behavior,ration and size structure of a population of the predatory gastropod <Emphasis Type="Italic">Cryptonatica janthostoma</Emphasis> in Vostok Bay,Sea of Japan

The relationships between the shell height of the predatory gastropod Cryptonatica janthostoma and the shell length of its typical prey, the bivalve Ruditapes philippinarum, and the diameter of the borehole on the prey shell resulting from a successful attack of the predator were experimentally found and assessed statistically. The shell height of C. janthostoma calculated retrospectively from the borehole diameter using the obtained relationships was 17–52 mm. The prey of C. janthostoma are burrowing bivalves, whose populations are affected by the predator to a varying degree. In populations of medium-sized mollusks (R. philippinarum, Protothaca euglypta, P. jedoensis, and others), C. janthostoma feeds on mollusks larger than 7–10 mm; in species with a shell length greater than 100 mm (Callista brevisiphonata, Saxidomus purpuratus), it eats specimens of 10–58 mm. C. janthostoma apparently has no effect on populations of small-sized mollusks (Anisocorbula venusta) and mollusks with an active avoidance response (Clinocardium californiense).     

A novel cysteine-rich antimicrobial peptide from the mucus of the snail of Achatina fulica

Antimicrobial peptides (AMPs) are important components of the innate immunity. Many antimicrobial peptides have been found from marine mollusks. Little information about AMPs of mollusks living on land is available. A novel cysteine-rich antimicrobial peptide (mytimacin-AF) belonging to the peptide family of mytimacins was purified and characterized from the mucus of the snail of Achatina fulica. Its cDNA was also cloned from the cDNA library. Mytimacin-AF is composed of 80 amino acid residues including 10 cysteines. Mytimacin-AF showed potent antimicrobial activity against Gram-negative and Gram-positive bacteria and the fungus Candida albicans. Among tested microorganisms, it exerted strongest antimicrobial activity against Staphylococcus aureus with a minimal peptide concentration (MIC) of 1.9 μg/ml. Mytimacin-AF had little hemolytic activity against human blood red cells. The current work confirmed the presence of mytimacin-like antimicrobial peptide in land-living mollusks.     

Mid-Neolithic Exploitation of Mollusks in the Guanzhong Basin of Northwestern China: Preliminary Results

Mollusk remains are abundant in archaeological sites in the Guanzhong Basin of Northwestern China, providing good opportunities for investigations into the use of mollusks by prehistoric humans. Here we report on freshwater gastropod and bivalve mollusks covering the time interval from about 5600 to 4500 cal. yrs BP from sites of Mid-Late Neolithic age. They are identified as Cipangopaludina chinensis and Unio douglasiae, both of which are currently food for humans. The shells are well preserved and have no signs of abrasion. They are all freshwater gastropods and bivalves found in pits without water-reworked deposits and have modern representatives which can be observed in rivers, reservoirs, and paddy fields in the studied region. Mollusk shells were frequently recovered in association with mammal bones, lithic artifacts, and pottery. These lines of evidence indicate that the mollusks are the remains of prehistoric meals. The mollusk shells were likely discarded into the pits by prehistoric humans after the flesh was eaten. However, these mollusk remains may not have been staple food since they are not found in large quantities. Mollusk shell tools and ornaments are also observed. Shell tools include shell knives, shell reaphooks and arrowheads, whereas shell ornaments are composed of pendants and loops. All the shell tools and ornaments are made of bivalve mollusks and do not occur in large numbers. The finding of these freshwater mollusk remains supports the view that the middle Holocene climate in the Guanzhong Basin may have been warm and moist, which was probably favorable to freshwater mollusks growing and developing in the region.     

Microhabitats within Venomous Cone Snails Contain Diverse Actinobacteria

Actinomycetes can be symbionts in diverse organisms, including both plants and animals. Some actinomycetes benefit their host by producing small molecule secondary metabolites; the resulting symbioses are often developmentally complex. Actinomycetes associated with three cone snails were studied. Cone snails are venomous tropical marine gastropods which have been extensively examined because of their production of peptide-based neurological toxins, but no microbiological studies have been reported on these organisms. A microhabitat approach was used in which dissected tissue from each snail was treated as an individual sample in order to explore bacteria in the tissues separately. Our results revealed a diverse, novel, and highly culturable cone snail-associated actinomycete community, with some isolates showing promising bioactivity in a neurological assay. This suggests that cone snails may represent an underexplored reservoir of novel actinomycetes of potential interest for drug discovery.Interest in natural products and drug discovery has been a major driving force for the study of microbial communities associated with marine invertebrates. Sponges, which have provided more bioactive metabolites than any other marine invertebrate group (see reference 4 and previous references in that series) have been the main focus of these investigations, yielding numerous reports of associated bacteria and complex microbial communities (17, 43). Other examples of marine invertebrate-associated microbes explored for their involvement in natural products include bryozoans (9, 41), ascidians (37), and shipworms (46). Thus far, there are literature reports of diverse bacterial taxa involved in natural product biosynthesis in marine animals (9, 10). Notably less well studied are the symbiotic actinomycetes, for which the biology of host-actinomycete associations is just beginning to be explored in a methodical way. Actinomycetes are known to be important symbionts in a number of biological systems, such as plants, insects, and marine invertebrates, contributing as nitrogen fixers in plants (39) or utilizing their chemical arsenal for defense purposes (8, 22, 38).An initial investigation of a cone snail yielded a surprisingly high number of actinomycetes (data not shown), prompting this follow-up study on additional samples. Cone snail mollusks belong to the genus Conus, which contains about 500 closely related species (11). These mollusks are well known for their complex neurologically active venoms that they use to immobilize their prey, including fish, worms, and other mollusks. The venom of cone snails has been extensively studied, but to our knowledge no study of cone snail microbial communities has been reported. Cone snails are part of the larger superfamily Conoidea, comprising ∼20,000 species, making it an extremely diverse group (25, 34). Given the initial observation of cultivable actinomycetes from cone snails, this large group seemed like a potentially excellent source of new bacterial natural products and new models of actinomycete symbiosis.The goal of this study was to examine the actinobacteria community associated with tropical marine snails of the genus Conus, using a microhabitat approach by which individual organs are treated as independent samples, and to assess the bioactivities of the isolates obtained by using a neurological assay. Although similar approaches have previously been used in microbial ecology (3, 42), this is a novel approach in drug discovery for the identification of bioactive bacteria. We report here the association between three cone snails, Conus pulicarius, Conus rolani, and Conus tribblei, and their actinobacteria as well as the bioactivities of some of these actinobacteria.     

Phylogenetic relationships and taxonomy of Altiplano populations of Biomphalaria (Gastropoda: Planorbidae): inference from a multilocus approach

Isolated closed basins provide a natural laboratory to study the differentiation among wild populations. Here we examined the phylogenetic relationships of the Southern Altiplano populations of Biomphalaria, a genus with medical importance, using nuclear (ITS1, ITS2) and mitochondrial (16S) ribosomal gene markers and a species of Helisoma as outgroup. Phylogenetic trees based on separate and combined analyses show that these populations form a particular lineage within Biomphalaria along with Biomphalaria peregrina (d'Orbigny, 1835) and Biomphalaria oligoza Paraense, 1974. The origin of this clade was estimated to have occurred in the middle Pleistocene. Molecular analyses showed that the nominal species Biomphalaria crequii ( Courty, 1907 ) from the Salar de Ascotán and Biomphalaria costata (Biese, 1951) from the Salar de Carcote, previously synonymized with Biomphalaria andecola (d'Orbigny, 1835) and B. peregrina, respectively, are distinct taxa. Molecular data did not resolve the relationship of Biomphalaria aymara Valdovinos & Stuardo, 1991 from the Isluga swamps to other Biomphalaria species, but confirm that the populations from the Lauca and Huasco basins may represent a distinct undescribed species of Biomphalaria from the Southern Altiplano. Snails examined for trematodes were found to be positive in some Altiplano localities. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 795–808.     

The role of <Emphasis Type="Italic">Viviparus contectus</Emphasis> (Millet) (Mollusca,Viviparidae) in the sedimentation of suspension and transformation of organic matter in the Tnya River (Ukraine)

As active filterers and sedimentators, mollusks Viviparus contectus (Millet) clear water from suspensions in the Tnya River. The sedimentation ability of mollusks is assessed on the basis of experimental studies at three stations using the funneling technique. Mollusks at the age of 3 and 5 years are used. The rate of sedimentation of V. contectus is 7.3 to 13.7 mg/(spec. day) in July 2014. The efficiency of suspended sedimentation is higher in younger individuals. The rate of sedimentation is determined by the total body weight of mollusks; the ratio between these parameters is described by the exponential function. V. contectus contributes to the decrease in the content of organic matter in the water with a rate of 0.055 to 0.069 mg of O₂/(dm³ spec. h), as well as to the enrichment of the near-bottom water layer with organic matter.     

Bioassays with freshwater snails Biomphalaria sp.: from control of hosts in public health to alternative tools in ecotoxicology

Ecotoxicology is the science responsible for the study of the adverse effects of chemicals on ecosystems considering biotic and abiotic components. Several invertebrate groups have long been used to evaluate the aquatic toxicity of chemical compounds. Among these organisms, the microcrustaceans are the most recommended in Brazilian and international protocols (e.g. Daphnia sp. and Ceriodaphnia sp.). Until the beginning of the 1990s, the use of mollusks with ecotoxicological purposes was non-existent, except for the species tested as target of molluscicides in public health studies. Since the second half of this same decade the tests with mollusks have begun to be disseminated in several countries, valuing endemic species and especially the scarcity of test species in benthic habitats. In the early 2000s, with the disclosure of the harmful effects of pollutants with endocrine disrupting properties, gastropods have begun to be used not to evaluate lethal effects, but rather to observe physiological effects such as reproduction and embryonic development. Since then, assays with these approaches, especially with freshwater snails Lymnaea stagnalis and Biomphalaria sp., have been considered to be innovative and highly sensitive, often more than those achieved with traditional groups of test organisms in ecotoxicology (such as microcrustaceans and fishes).     

Genetic characterisation of the intermediate hosts of schistosomiasis in its southern distribution limit in South America

ABSTRACT

Schistosomiasis is a tropical disease caused by the digenean parasite Schistosoma mansoni. In South America it is transmitted to humans via freshwater snails of the genus Biomphalaria. In a global warming scenario, disease range expansions to subtropical countries are possible. For the first time, the distributions and genetic identification of Biomphalaria specimens in border regions of Uruguay are reported. The inclusion of Uruguayan samples allows a better understanding of the relationships between and within taxa of Biomphalaria. Samples were collected between 2015 and 2016 using hand nets. Initially, they were classified morphologically. They were then classified genetically by analysing a fragment of the cytochrome c oxidase subunit I gene. Phylogenetic analysis revealed the presence of B. peregrina and B. occidentalis. Species belonging to the B. tenagophila complex were also recognised. Individuals initially identified from their external morphology as B. tenagophila tenagophila showed inconsistencies with the analysis of COI sequences that assigned them to B. occidentalis. Since the presence of schistosomiasis in Uruguay is likely to occur in the next few years, an exhaustive population survey of Biomphalaria taxa should be urgently developed to identify the presence of S. mansoni and the places most susceptible to be colonised by these snails.     

Assessment of the genetic distances between some species of the family Bradybaenidae (Mollusca,Pulmonata)

On the basis of inter-simple sequence repeat (ISSR) loci and the nucleotide sequences of nuclear (18S and ITS-1) and mitochondrial genes (COI and 16S), a phylogenetic analysis of the three species of terrestrial mollusks of the family Bradybaenidae (Mollusca, Pulmonata), Bradybaena fruticum Müll., Bradybaena schrencki Midd., and Bradybaena transbaicalia Shileyko, was conducted to clarify their taxonomic status. The analysis showed that Br. fruticum was far apart from the other two species (Br. schrencki and Br. transbaicalia). The genetic distance between the latter puts in doubt their status as distinct species. It is suggested that the species Br. transbaicalia can be treated as a form of Br. schrencki var. transbaicalia.     

Clonal and population RAPD variation of cercariae obtained from <Emphasis Type="Italic">Bucephalus polymorphus</Emphasis> sporocysts (Trematoda: Bucephalidae)

Three arbitrary primers produced 114 RAPD markers for 37 cercariae from nine Bucephalus polymorphus sporocysts obtained from three Dreissena polymorpha mollusks, which were collected in two water reservoirs of the Volga basin. Analysis of the RAPD patterns established a unique genotype for each cercaria. The topology of an UPGMA dendrogram did not reliably differentiate the cercaria according to the corresponding sporocysts. However, three groups of genotypes were isolated and corresponded to the host mollusks, indicating that each cercaria clone had a different genotype set. A within-sporocyst variation made the greatest contribution (53.0%) to the total RAPD diversity, while the contributions of within-host and between-host variations to the total diversity were equal (23.5%). Cercariae isolated from two mollusks of the Rybinskoe Water Reservoir were more similar to each other than to cercariae from the geographically distant Gor’kovskoe Water Reservoir. Possible causes and distribution specifics of the observed genetic diversity of B. polymorphus are discussed.     

Biomphalaria species in Alexandria water channels

Of the several species of Biomphalaria snails worldwide that serve as the intermediate host for Schistosoma mansoni, Biomphalaria alexandrina is a species that is indigenous to Egypt. Recently, there has been much debate concerning the presence of Biomphalaria glabrata and the hybrid of the species with Biomphalaria alexandrina. Due to this debate, the absence of a clear explanation for the presence of B. glabrata in Egyptian water channels and the probability that they may be reintroduced, we conducted this field study to identify Biomphalaria species present in Alexandria water channels. Laboratory-adapted susceptible snails to Schistosoma mansoni of the following species were used as a reference; Biomphalaria alexandrina, Biomphalaria glabrata and their hybrid. These snails were used to perpetuate the Schistosoma life cycle at the Theodor Bilharz Research Institute (TBRI), Cairo, Egypt. Morphological and molecular studies were conducted on these reference snails as well as on the first generation of Biomphalaria snails from two areas in the Alexandria governorate. The morphological study included both external shell morphology and internal anatomy of the renal ridge. The molecular study used a species-specific PCR technique.The results demonstrated that there was an absence of Biomphalaria glabrata and the hybrid from Alexandria water channels. Moreover, the susceptibility patterns of these reference snails were studied by measuring the different parasitological parameters. It was found that Biomphalaria glabrata and the hybrid were significantly more susceptible than Biomphalaria alexandrina to the Egyptian strain of Schistosoma mansoni. The results demonstrated that if Biomphalaria glabrata was reintroduced and adapted to the local environment in Egypt, it would have important epidemiologic impacts that would have a serious effect on the health of Egyptian people.     

Histamine Immunoreactive Elements in the Central and Peripheral Nervous Systems of the Snail,Biomphalaria spp., Intermediate Host for Schistosoma mansoni

Histamine appears to be an important transmitter throughout the Animal Kingdom. Gastropods, in particular, have been used in numerous studies establishing potential roles for this biogenic amine in the nervous system and showing its involvement in the generation of diverse behaviours. And yet, the distribution of histamine has only previously been described in a small number of molluscan species. The present study examined the localization of histamine-like immunoreactivity in the central and peripheral nervous systems of pulmonate snails of the genus Biomphalaria. This investigation demonstrates immunoreactive cells throughout the buccal, cerebral, pedal, left parietal and visceral ganglia, indicative of diverse regulatory functions in Biomphalaria. Immunoreactivity was also present in statocyst hair cells, supporting a role for histamine in graviception. In the periphery, dense innervation by immunoreactive fibers was observed in the anterior foot, perioral zone, and other regions of the body wall. This study thus shows that histamine is an abundant transmitter in these snails and its distribution suggest involvement in numerous neural circuits. In addition to providing novel subjects for comparative studies of histaminegic neurons in gastropods, Biomphalaria is also the major intermediate host for the digenetic trematode parasite, which causes human schistosomiasis. The study therefore provides a foundation for understanding potential roles for histamine in interactions between the snail hosts and their trematode parasites.     

Ecological differentiation of resident Dolly Varden <Emphasis Type="Italic">Salvelinus malma</Emphasis> (Salmonidae) from Lake Dal’nee,Kamchatka

Resident Dolly Varden Salvelinus malma of Lake Dal’nee (Paratunka River basin) is represented by two stable trophic groups: one group feeds on mainly amphipods while another on gastropods. The former group is dominantly infected by Cyathocephalus truncatus and Crepidostomum metoecus, whereas the latter group is infected with Crepidostomum farionis, Ichthyocotylurus erraticus, and Diplostomum spp. The fishes of the former group grow faster and defined by higher fat content of muscular tissue. In addition, they accumulate monoenic fatty acids in the muscles. The fishes of the latter group differ in a high content of omega-3 and omega-6 fatty acids in the muscles. The amphipod foragers are characterized by a larger head with elongated upper jaw and comparatively short fins. A similar ecological differentiation is observed in the littoral benthivorous charrs from Lake Kronotskoe. The group feeding on amphipods was found in both lakes. In Lake Kronotskoe, the second group consumes the most abundant sedentary benthos, mollusks and chironomids.     

Transmission studies of intestinal schistosomiasis in Lake Albert,Uganda and experimental compatibility of local Biomphalaria spp.

Despite ongoing preventive chemotherapy campaigns, intestinal schistosomiasis is hyper-endemic in shoreline communities living along Lake Albert, Uganda. To provide a deeper insight into the local epidemiology of Schistosoma mansoni, a variety of field-based studies were undertaken focusing upon schistosome–snail interactions and confirmation of transmission foci. Cercarial shedding patterns of field-caught Biomphalaria spp., as identified by morphology, were hourly observed over a ten day period and showed that Biomphalaria stanleyi produced significantly more cercariae than Biomphalaria sudanica. Peak production times in both species were between 12.00 and 14.00 h indicating greatest infection risk from lake water exposure is during the early afternoon. Laboratory-bred snails were exposed to locally hatched miracidia and susceptibility of Biomphalaria spp. was confirmed experimentally. Biomphalaria stanleyi was a more permissive host. After ascertaining appropriate conditions for infection of laboratory mice, 28 groups of between 5 and 6 naïve mice were placed in floatation cages at four suspected shoreline transmission sites for a 30 minute period of exposure. Eight weeks later, mice (n = 142) were culled and S. mansoni adult worms were retrieved from 10 animals. Taken as a whole, these observations highlight the local importance of B. stanleyi in transmission of intestinal schistosomiasis and clearly demonstrate the risk of infection on the Lake Albert shoreline. To mitigate this risk local environmental modification(s), i.e. improvement in sanitation and hygiene and control of snail populations, is needed to bolster the impact of chemotherapy-based interventions.