Snail Tissues Research Articles

A Comparative Transcriptomics Approach to Analyzing the Differences in Cold Resistance in Pomacea canaliculata between Guangdong and Hunan

Pomacea canaliculata, known as an invasive freshwater snail, is also called a golden apple snail; its survival and expansion are greatly affected by temperature. In this study, high-throughput sequencing (RNA-seq) was used to perform comparative transcriptome analysis on the muscular tissue (G_M) of snails in Guangdong and Hunan. Differential gene screening was performed with FDR <0.05 and |log2FoldChange| >1 as the threshold, and a total of 1,368 differential genes were obtained (671 genes showed upregulation in snails from Guangdong, and 697 genes displayed upregulation in snails from Hunan). Fifteen genes were identified as candidate genes for the cold hardiness of Pomacea canaliculata. Among them, three genes were involved in energy metabolism (glycogen synthase, 1; DGK, 1; G6PD, 1); seven genes were involved in homeostasis regulation (HSP70, 2; BIP, 1; GPX, 1; GSTO 1, G6PD, 1; caspase-9, 1); two genes were involved in amino acid metabolism (glutamine synthetase, 1; PDK, 1); and four genes were involved in membrane metabolism (inositol-3-phosphate synthase, 1; Na+/K+-ATPase, 1; calcium-binding protein, 2). This study presents the molecular mechanisms for the cold hardiness of Pomacea canaliculata, which could provide a scientific basis for the forecast and prevention of harm from Pomacea canaliculata.

Use of Two Aquatic Snail Species as Bioindicators of Heavy Metals in Tigris River-Baghdad

Thirty individuals of Bellamya bengalensis and Physella acuta were collected and identified from the Tigris River in Baghdad during the period between October to November 2017. The efficiency of bioaccumulation of the two species as bioindicators for aquatic heavy metal pollution with Cd, Ni, Pb and Cu was investigated. Both snail species had the ability to accumulate heavy metals. The mean of Ni concentration in soft tissues of both snails was 1.53 ppm while the mean concentration of other heavy metals was significantly lower; they reached 0.51 ppm, 0.36 ppm and 0.29 ppm, respectively. While no significant differences between B. bengalensis and P.acuta were noticed in the ability to accumulate the heavy metals. It is concluded that both snails shared the features of good bioindicators due to their sensitivity to pollution.:

Establishment of a recombinase-aided isothermal amplification assay for nucleic acid detection of Angiostrongylus cantonensis

To establish a recombinase-aided isothermal amplification (RAA) assay for the nucleic acid detection of Angiostrongylus cantonensis. The internal transcribed spacer-1 (ITS1) gene sequence of A. cantonensis was used as the detection target sequence, and the specific primers and probes were designed and synthesized, followed by screening of the primers and probes with the highest specificity, to establish the basic and fluorescent RAA assay for nucleic acid detection of A. cantonensis. The sensitivity of the fluorescent RAA assay was evaluated by using the target gene fragment sequence-contained recombinant plasmids at various copy numbers and the genomic DNA from A. cantonensis as the template DNA samples, and the specificity of the fluorescent RAA assay was evaluated by using the genomic DNA from A. cantonensis, Schistosoma mansoni, Ascaris lumbricoides, Clonorchis sinensis, Echinococcus granulosus and Ancylostoma duodenale, as well as Pomacea canaliculata and Biomphalaria straminea snail tissues as the template DNA samples. A fluorescent RAA assay was successfully established for nucleic acid detection of A. cantonensis, which achieved real-time amplification of the specific DNA fragment of A. cantonensis within 20 min at 37 ℃. By using the target gene fragment sequence-contained recombinant plasmids at various copy numbers and the genomic DNA from A. cantonensis as the DNA templates, the lowest detection limits of the fluorescent RAA assay were 10 copies/μL of recombinant plasmids and 100 pg/μL of genomic DNA, respectively. The fluorescent RAA assay was negative for detection of the genomic DNA from A. cantonensis, S. mansoni, A. lumbricoides, C. sinensis, E. granulosus, A. duodenale, and P. canaliculata and B. straminea snail tissues. A simple, rapid fluorescent RAA assay has been successfully established, which has a high sensitivity and specificity for the nucleic acid detection of A. cantonensis.

Functional shell matrix proteins tentatively identified by asymmetric snail shell morphology

Molluscan shell matrix proteins (SMPs) are essential in biomineralization. Here, we identify potentially important SMPs by exploiting the asymmetric shell growth in snail, Lymnaea stagnalis. Asymmetric shells require bilaterally asymmetric expression of SMP genes. We examined expression levels of 35,951 transcripts expressed in the left and right sides of mantle tissue of the pond snail, Lymnaea stagnalis. This transcriptome dataset was used to identify 207 SMPs by LC-MS/MS. 32 of the 207 SMP genes show asymmetric expression patterns, which were further verified for 4 of the 32 SMPs using quantitative PCR analysis. Among asymmetrically expressed SMPs in dextral snails, those that are more highly expressed on the left side than the right side are 3 times more abundant than those that are more highly expressed on the right than the left, suggesting potentially inhibitory roles of SMPs in shell formation. The 32 SMPs thus identified have distinctive features, such as conserved domains and low complexity regions, which may be essential in biomineralization.

Toxic Elements and Mineral Content of Different Tissues of Endemic Edible Snails (Helix vladika and H. secernenda) of Montenegro.

The objective of the present study is to determine the differences between the mineral content of various organs of Helix vladika and H. secernenda, the two most abundant edible snail species in Montenegro. The bioaccumulation of 12 examined elements (zinc, manganese, copper, aluminum, cadmium, lead, nickel, iron, chromium, lithium, selenium and mercury) was determined in the hepatopancreas, albumen gland, digestive tract, reproductive system, mantle, foot and shell from three sampling sites (Biogradska Gora, Nikšić and Malesija). The examined populations of H. vladika and H. secernenda showed a significant difference in their lithium and selenium contents. The levels of the most examined metals (Zn, Mn, Cu, Al, Cd, Pb, Se and Hg) varied significantly among organs. The digestive tract and hepatopancreas tend to bioaccumulate selenium and cadmium. The general mean concentration of cadmium in the examined snail tissues exceeded the maximum allowable level at the Biogradska Gora and Malesija sites. Therefore, the use of the Montenegrin edible snails collected from the wilderness for human consumption seems to be limited by their higher bioaccumulation capacity for toxic elements such as cadmium.

Biochemical and apoptotic changes in the nervous and ovotestis tissues of Biomphalaria alexandrina following infection with Schistosoma mansoni

Infection with trematodes produces physiological and behavioural changes in intermediate snail hosts. One response to infection is parasitic castration, in which energy required for reproduction of the host is thought to be redirected to promote development and multiplication of the parasite. This study investigated some reproductive and biochemical parameters in the nervous (CNS) and ovotestis (OT) tissues of Biomphalaria alexandrina during the course of Schistosoma mansoni infection. Antioxidant and oxidative stress parameters including catalase (CAT), nitric oxide (NO) and lipid peroxidation (MDA) were measured. Levels of steroid hormones, including testosterone, progesterone and estradiol, were also assessed. Finally, flow cytometry was used to compare measures of apoptosis between control snails and those shedding cercariae by examining mitochondrial membrane potential with the stain 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimi-dazolylcarbocyanine iodide (JC-1) and poly(ADP-ribose) polymerase (PARP). Infection with S. mansoni caused a 47.7% reduction in the net reproductive rate (Ro) of B. alexandrina. CAT activity was increased in the CNS at 21 days post infection (dpi) but by 28 dpi it was reduced below control values. Also, CAT activity increased significantly in the OT at 14, 21 and 28 dpi. In CNS tissues, NO levels were reduced at 7 dpi, increased at 14 and 21 dpi, and reduced again at 28 dpi. The overall level of lipid peroxidation gradually increased during the course of infection to reach its highest levels at 28 dpi. Steroid hormone measurements showed that concentrations of testosterone and estradiol were reduced in the CNS tissues at 28 dpi, while those of progesterone were slightly increased in the CNS and OT tissues. The percentage of cells that positively stained with JC-1was significantly increased in CNS and OT tissues of infected snails while the percentage of cells positively stained with PARP was decreased compared to controls. Together, these findings indicate that infection initiates diverse biochemical and hormonal changes leading to loss of cells responsible for egg laying and reproduction in B. alexandrina.

The Chronology of Angiostrongylus vasorum (Baillet, 1866), Kamensky, 1905: Infection in Biomphalaria glabrata (Say, 1818).

The intermediate hosts of the French heartworm Angiostrongylus vasorum are aquatic and terrestrial gastropods. The present work is aimed at clarifying the sites of penetration and the migratory routes of A. vasorum in Biomphalaria glabrata snail tissues and evaluating their perilarval reaction with regard to the cellular composition and histological alterations involved in the gastropod response to infection. Biomphalaria glabrata snails were individually infected with 1000 first-stage larvae (L1) of A. vasorum each and killed at predetermined times after infection. Percutaneous infection occurred simultaneously with oral infection. Despite larval tropism to the fibromuscular tissue, some larvae were located in different tissues and organs. A perilarval reaction was observed around the larvae in a fibromuscular layer, appearing later around the larvae located in the viscera. The number of hemocytes surrounding the larvae increased gradually, forming a pregranuloma. Larval death and degeneration were not observed. No defined migratory pattern occurred, and larval development was apparently not associated with particular tissues or organs. In addition, the infection by A. vasorum induces a systemic mobilization of hemocytes in perilarval reaction.

Population genetics of invasive Pomacea spp. in Hangzhou City, Zhejiang Province

To investigate the distribution and identify the genetic genetics of invasive Pomacea species in Xihu District, Hangzhou City, so as to understand the spread tendency of Pomacea species. The specimens of Pomacea species were collected from five sites in water systems (lakes, rivers and wetlands) and its costal lands in Xihu District, Hangzhou City in 2017 for morphological identification. Total DNA was isolated from the foot tissues of adult snails for amplification of the COI gene, and haplotype diversity and nucleic acid diversity analyses were performed. In addition, a phylogenetic tree was created based on the haplotype captured from GenBank and those from this study to investigate the phylogenetic relationships. Pomacea specimens, which were preliminarily characterized as Pomacea, were found in ponds, rivers and wetlands in Xihu District of Hangzhou City. A total of 16 sequences were captured from the DNA samples of Pomacea specimens, which belonged to 3 haplotypes, including Hap1, Hap2 and Hap3. A high frequency was seen in Hap1 and Hap3, and a low frequency was found in Hap2. The Pomacea specimens collected from the 5 sites in Xihu Districts included P. canaliculata and P. maculate. The Pomacea specimens with a Hap1 had a close genetic relationship with the P. canaliculata from Argentina, Guangdong Province and Hong Kong Special Administrative Region of China, and the Pomacea specimens with a Hap2 had a close genetic relationship with the P. canaliculata from Argentina, Japan and Guangzhou City of Guangdong Province, China, while the Pomacea specimens with a Hap2 had a close genetic relationship with the P. maculate from Argentina and Brazil. P. canaliculata and P. maculata are present in Xihu District of Hangzhou City. P. maculata may spread to Xihu District through multiple introductions or water flow.

Acute Toxicity, Bioaccumulation, and Bioreduction of Two Antibiotics, Norfloxacin and Ofloxacin, in the Snail Bellamya aeruginosa

Fluoroquinolones (FQs) present in water environments pose threats to aquatic organisms. The concentration of FQs adsorbed onto sediments is generally higher than that in water. Here, we studied the toxicities of two FQ antibiotics, norfloxacin (NOR) and ofloxacin (OFL), on the snail Bellamya aeruginosa, an adaptable benthic animal. For this, we performed acute toxicity experiments on young snails and sub-chronic exposure experiments on adult snails by exposure to the FQs for 1–28 days. The 96 h median effective concentrations showed that NOR toxicity was higher than OFL toxicity, although both NOR and OFL were low-toxicity substances (EC50 > 100 mg L−1). Four concentrations were used in the sub-chronic exposure experiments. Results of the measurement of bioconcentration factors (BCF) showed that OFL accumulation was higher than NOR accumulation in snail tissues. During the depuration period (28–49 days), at low concentrations (2 and 20 μg L−1), both FQs required at least 7 days to reach the maximum residue limit (50 μg kg−1). Conversely, at high concentrations (200 and 2000 μg L−1), 14 days (NOR) and 21 days (OFL) were required. Our results could facilitate management of the environmental risks of antibiotics and conservation of aquatic animals.

Identification of neuropeptides in gastropod mollusks. - Classical and brand-new approaches –

For the understanding of the neural regulation of homeostasis, reproduction and behaviors, elucidation of structure and function of neuropeptides is inevitable. A classical technique for peptide purification is the separation of peptidic extract from nervous tissue by the high-performance liquid chromatography, which was followed by screening of fractions with biological or immunological assays. Although this approach requires relatively large amount of tissues for extraction and the screening is time- consuming, we have identified more than 15 kinds of bioactive neuropeptides in the nervous tissue of a marine snail, Thais clavigera. The purified peptides include TEP (Thais excitatory peptide)-1/-2, FRFamide, WWamide and others. The molecular cloning of precursor for each neuropeptide demonstrated that structurally related peptides are aligned in tandem on most of the precursor proteins. To identify the peptides on the precursors, we conducted the de novo sequencing of peptides with the nanoLC-Orbitrap-MS/MS analysis. It identified most of the neuropeptides found on the precursor proteins in the extract from 50 of Thais ganglia. Thus, this technique is suitable for the comprehensive identification of peptides from relatively small amount of tissues. However, several peptides that had been identified by the classical technique, such as APGWamide and leucokinin, were not identified, suggesting the limitation of this brand-new technique.

Glabralysins, Potential New β-Pore-Forming Toxin Family Members from the Schistosomiasis Vector Snail Biomphalaria glabrata.

Biomphalaria glabrata is a freshwater Planorbidae snail. In its environment, this mollusk faces numerous microorganisms or pathogens, and has developed sophisticated innate immune mechanisms to survive. The mechanisms of recognition are quite well understood in Biomphalaria glabrata, but immune effectors have been seldom described. In this study, we analyzed a new family of potential immune effectors and characterized five new genes that were named Glabralysins. The five Glabralysin genes showed different genomic structures and the high degree of amino acid identity between the Glabralysins, and the presence of the conserved ETX/MTX2 domain, support the hypothesis that they are pore-forming toxins. In addition, tertiary structure prediction confirms that they are structurally related to a subset of Cry toxins from Bacillus thuringiensis, including Cry23, Cry45, and Cry51. Finally, we investigated their gene expression profiles in snail tissues and demonstrated a mosaic transcription. We highlight the specificity in Glabralysin expression following immune stimulation with bacteria, yeast or trematode parasites. Interestingly, one Glabralysin was found to be expressed in immune-specialized hemocytes, and two others were induced following parasite exposure.

Content of vitamin C in edible tissues of snails obtained in Poland

Ascorbic acid (Vit. C) is essential for the proper functioning of the human body. Humans are unable to synthesize vitamin C endogenously, so it must be supplied with food. The available literature does not provide any data on the content of vitamin C in the meat of snails. The aim of the study was therefore to determine and compare its content in the edible parts of snails obtained in Poland. The research material consisted of 30 samples of snail meat (the foot with the collar and a fragment of the coat) belonging to three species: Helix pomatia, Cornu aspersum aspersum, and Cornu aspersum maxima. Helix pomatia snails were obtained from the natural environment, while the other two species came from commercial breeding farms. Ascorbic acid was determined by the method of Roe and Kuethner, as modified by Dabrowski and Hinterleitner (1989). Previously, tissues for biochemical analysis were prepared according to the methodology described by Zannoni et al. (1974). The average level of vitamin C in the edible parts of particular snail species ranged from 38.14 mg/kg (Helix pomatia) to 185.38 mg/kg (Cornu apsersum aspersum). Statistically significant differences in the level of ascorbic acid were found between all species of snails examined. The highest vitamin C content was found in the meat of Cornu aspersum aspersum. The lowest level of ascrobic acid occurred in the meat of Helix pomatia, in which it was 20.41% and 37.04% of the levels found in the meat of Cornu aspersum aspersum and Cornu aspersum maxima, respectively. The present research showed a significantly higher content of ascorbic acid in snails of the Cornu genus kept in heliculture as compared to free-living snails (Helix pomatia). Moreover, the content of ascorbic acid in the edible parts of snails is higher than it is in pork and beef meat. The present study showed that snails from the Cornu genus can be an additional valuable source of vitamin C in the human diet.

Effect of amendments on soil Cd sorption and trophic transfer of Cd and mineral nutrition along the food chain.

Phytotoxicity of cadmium (Cd) and its trophic transfer along a terrestrial food chain have been extensively investigated. However, few studies focused on the role of amendments on the trophic transfer of Cd and related mineral nutrients. In a 60-day pot experiment, soil Cd availability, accumulation of Cd, mineral nutrients (Ca and Si) in lettuce, and subsequent trophic transfer along the lettuce-snail system were investigated with or without 3% (w/w) soil amendment (biochar or micro-hydroxyapatite, μHAP). Soil CaCl2 extractable Cd (CdCaCl2) contents decreased by both amendments. μHAP amended soil increased the Freundlich sorption capacity of Cd2+ to a greater extent (15.9mmol/kg) than biochar (12.6mmol/kg). Cd, Ca and Si accumulation in lettuce tissues (roots and shoots) varied with amendment species and soil Cd levels. Linear regression analysis showed that root Cd contents are negatively correlated with root Ca and Si contents (r2=0.96, p<0.05). But no significant correlation between shoot Cd and lettuce Ca and Si contents was found (p>0.05). After 15 days snail feeding, nearly 90% content of Cd was found in snail viscera, while nearly 95% content of Ca was found in snail shells. Contents of Si distributed equally in snail tissues. Biomagnification of Cd, Ca and Si (TF>1) was found in lettuce shoot - snail viscera system. Opposite tendency of TF variation between Cd and nutrient elements (Ca and Si) from shoots to snail tissues indicated that μHAP, rather than biochar, amendment is applicable to remediate soil Cd contamination in our study.

Assessment of the fate and effect of ivermectin in a simulated aquaculture ecosystem

As a potent anti‐parasitic agent, ivermectin (IVM) has been commonly used by the aquaculture industry. In this study, the environmental fate and effects of IVM in a simulated aquaculture ecosystem were evaluated. The simulated ecosystem was composed of water, sediment, aquatic plants, invertebrates and fish. According to the new fishery drugs manual, IVM was introduced into the water at a final concentration of 1.6 × 10–⁴ mg·L–¹. The samples, including the roots and leaves of aquatic plants, the visceral mass and muscle of fish, the soft tissue of mud snails, sediment and water were collected at 0.5 hr, 1, 7, 15, 30, 45, 60 and 70 days after the treatment. Our results indicated that IVM was distributed quickly and widely into the whole ecosystem and accumulated to high levels in organisms resulting in residues that persisted for a long time. The IVM concentration in the sediment increased continuously and reached a peak (2.896 ng·g–¹) at 30 days. Moreover, the concentration of IVM in the water declined from 0.5 hr to 1 day and then increased to a peak of 0.130 ng·mL–¹ at 7 days. The IVM concentrations in the fish reached a peak in muscle (192.10 ng·g–¹) and visceral mass (259.82 ng·g–¹) at 7 days. IVM was quickly accumulated by the aquatic plants, and it was found at higher levels in the leaves than in the roots. The IVM concentration in the mud snails reached its peak with a value of 24.750 ng·g–¹ at 7 days and then decreased quickly at 15 days. It was notable that a second peak of IVM accumulated in the fish and aquatic plants after 30 days. The aquaculture ecosystem simulated in this study was feasible and effective and could be applied to assess the fate of IVM in aquatic environments.

Cytotoxic effects of persistent organic pollutants on the freshwater snail (Lanistes carinatus) in Kafr El-Zayat, Egypt

Effects of industrial and municipal wastewaters on the freshwater snail, Lanistes carinatus, were evaluated. Concentrations of some chemicals in some effluents were greater than permissible limits promulgated internationally by various jurisdictions. Pesticides and polychlorinated biphenyls (PCBs) observed in tissues of snails collected during summer were greater than those measured in snails collected during winter. Catalase activities observed during autumn were greater than those observed during other seasons. Activities of catalase were greater at all sites near sources of contamination than in snails from the reference site (S6). Lactate dehydrogenase activity was also greater at all sites relative to the location designated as the reference (S6), at which activities did not exceed 8.10 U/L. Patterns of genomic DNA in snails, as determined by use of OPA-02 primer, were significantly different among sites. Location S1 (Belshay village) exhibited 11 bands, followed by S2 (El-Demer zone) and S5 (Rosetta branch) which exhibited 6 bands. In contrast, all sites exhibited greater numbers of bands when the OPA-08 primer was used. Thus, DNA fingerprinting, lactate dehydrogenase, and catalase offer useful biomarkers in ecotoxicology and risk assessment programs.

Biomphalaria alexandrina: a model organism for assessing the endocrine disrupting effect of 17β-estradiol.

A wide range of endocrine disruptor compounds are routinely discharged to the ecosystem. Water contaminated with these compounds has a potential effect on the reproductive physiology of aquatic organisms as well as humans. In the present study, we tested the effect of the steroid estrogen, 17β-estradiol, on Biomphalaria alexandrina, a snail species that is widely distributed in Egypt and that acts as an intermediate host for the human blood fluke, Schistosoma mansoni. The effects of exposure to 0.3mg/L and 1mg/L 17β-estradiol on fecundity (MX) and reproductive rate (R0) of B. alexandrina were recorded. In addition, levels of steroid sex hormones and antioxidants in the hemolymph and ovotestis (OT) of exposed snails were measured. Histopathological changes in the OT of B. alexandrina were also investigated. Exposure to 0.3mg/L and 1mg/L 17β-estradiol caused a significant increase in the number of egg masses per snail after 3weeks and 1week of exposure for the two tested concentrations compared with unexposed controls. An increase in the levels of progesterone hormone was recorded in the hemolymph of exposed snails in comparison with unexposed controls. Additionally, levels of the antioxidant enzyme glutathione (GSH) were increased in the hemolymph and OT tissues of snails after 2 and 4weeks of exposure. Histopathological sections in the OT revealed an increase in the oocyte and a decrease in the sperm densities after 2weeks and this effect was restored to normal conditions after 4weeks of exposure to both tested concentrations. The current results indicate that B. alexandrina is sensitive to 17β-estradiol and can therefore be used as bioindicator and model organism for the assessment of water pollution with endocrine disruptor compounds.

Biological activities of endozoic fungi isolated from Biomphalaria alexandrina snails maintained in different environmental conditions

ABSTRACT This work aims at studying Biomphalaria alexandrina snails as a source of bioactive compounds. Adult snails were maintained in plastic, mud and cement matrices. Three groups were prepared; under normal laboratory conditions, in slightly low pH conditions, and in high temperature (30°C) conditions. Nine fungal species were isolated from soft tissues of snails. Ethyl acetate and acetone extracts were prepared from each fungal species, and their biological activities were investigated. Paecilomyces variotii extracts were the most effective as antimicrobial agents, while acetone extract of Trichoderma harzianum showed high antioxidant activity. Acetone extracts of Penicillium islandicum and Aspergillus niger were highly active against hepatocellular carcinoma (HepG2) cell lines. Gas chromatography/mass spectrometry analysis of the five effective extracts showed the presence of various compounds. B. alexandrina snails may be regarded as a newly discovered source of beneficial compounds through the metabolites produced by their endozoic fungal strains.

Bioaccumulation of some trace elements in tropical mangrove plants and snails (Can Gio, Vietnam)

Mangrove sediments can store high amount of pollutants that can be more or less bioavailable depending on environmental conditions. When in available forms, these elements can be subject to an uptake by mangrove biota, and can thus become a problem for human health. The main objective of this study was to assess the distribution of some trace elements (Fe, Mn, Co, Ni, Cr, As, and Cu) in tissues of different plants and snails in a tropical mangrove (Can Gio mangrove Biosphere Reserve) developing downstream a megacity (Ho Chi Minh City, Vietnam). In addition, we were interested in the relationships between mangrove habitats, sediment quality and bioaccumulation in the different tissues studied. Roots and leaves of main mangrove trees (Avicennia alba and Rhizophora apiculata) were collected, as well as different snail species: Chicoreus capucinus, Littoraria melanostoma, Cerithidea obtusa, Nerita articulata. Trace elements concentrations in the different tissues were determined by ICP-MS after digestion with concentrated HNO3 and H2O2. Concentrations differed between stands and tissues, showing the influence of sediment geochemistry, species specific requirements, and eventually adaptation abilities. Regarding plants tissues, the formation of iron plaque on roots may play a key role in preventing Fe and As translocation to the aerial parts of the mangrove trees. Mn presented higher concentrations in the leaves than in the roots, possibly because of physiological requirements. Non-essential elements (Ni, Cr and Co) showed low bioconcentration factors (BCF) in both roots and leaves, probably resulting from their low bioavailability in sediments. Regarding snails, essential elements (Fe, Mn, and Cu) were the dominant ones in their tissues. Most of snails were “macroconcentrators” for Cu, with BCF values reaching up to 42.8 for Cerithidea obtusa. We suggest that high quantity of As in all snails may result from its high bioavailability and from their ability to metabolize As.

Molecular detection of natural infection of Lymnaea (Pseudosuccinea) columella (Gastropoda: Lymnaeidae) with Fasciola gigantica (Digenea: Fasciolidae) from two provinces of South Africa.

The main intermediate host of Fasciola gigantica in sub-Saharan Africa is Lymnaea (Radix) natalensis. Lymnaea (Pseudosuccinea) columella is capable of transmitting both F. gigantica and F. hepatica and has been reported to be present in South Africa. To date, no natural infection with F. gigantica has been reported despite the wide distribution of the snail. The aim of this study was to confirm whether L. (P.) columella was transmitting F. gigantica and/or F. hepatica in selected locations of KwaZulu-Natal and Eastern Cape provinces of South Africa. Lymnaea (Pseudosuccinea) columella snails were collected from two locations in two provinces of South Africa and screened for cercariae shedding. This was followed by humanely sacrificing the screened snails, and whole tissue of each individual snail was homogenized and amplified using primers designed to amplify the ITS-1 region of Fasciola spp. No cercariae were shed from the screened snails and molecular analysis showed that snails from the two locations were infected with F. gigantica. This study confirms natural infection of L. (P.) columella with F. gigantica in South Africa, where F. gigantica and F. hepatica have already been reported to coexist. Although L. (P.) columella is able to transmit the two species, surprisingly no infection with F. hepatica was detected from the screened snails. The natural intermediate host of F. gigantica in southern Africa, including South Africa, is Lymnaea (Radix) natalensis and comparative studies are needed to determine the competence of the two snail species in the transmission of F. gigantica.

Confirmation of the presence of Angiostrongylus cantonensis in lung tissue of the African giant snail (Lissachatina fulica) in Colombia

Objetive: To confirm the presence of Angiostrongylus cantonensis in Lissachatina fulica individuals in Colombia.Methods: 19 individuals of L. fulica were collected in the city of Buenaventura, Valle del Cauca, Colombia. Lung tissue was extracted and two analysis methods were used: visual identification by histological observation, and identification through conventional and real-time PCR. The A. cantonensis detection rate was established taking into account each of the analysis techniques used.Results: Presence of A. cantonensis was confirmed in the lung tissue of L. fulica specimens collected in the city of Buenaventura, Valle del Cauca, Colombia. The detection rate based on visual identification through histological analysis was 89%, whereas it was 95% using conventional PCR, and 100% using real-time PCR.Conclusion: This study confirmed for the first time the presence of A. cantonensis associated with L. fulica specimens in Colombia. Therefore, eosinophilic meningitis could be considered an emerging disease in Colombia.