Biological properties of mucus from land snails (Lissachatina fulica) and freshwater snails (Pomacea canaliculata) and histochemical study of mucous cells in their foot

Background Mucus derived from many land snails has been extensively utilised in medicine and cosmetics, but some biological activities of the mucus need to be well documented. Nevertheless, most mucus is obtained from land snails, while mucus from freshwater snails has yet to be attended. Methods This study aims to determine and compare mucus’s antioxidant and anti-inflammatory activities from the land snail Lissachatina fulica and the freshwater snail Pomacea canaliculata. ABTS, DPPH, reducing power and total antioxidant activity assays were used to evaluate the antioxidant capacity. Inhibition of nitric oxide production in lipopolysaccharide-activated RAW 264.7 cells was performed to determine the anti-inflammatory activity. Additionally, the histochemical analysis of mucous cells in each snail foot was conducted to compare the distribution of mucous cells and types of mucins using periodic acid-Schiff and Alcian blue staining. Results Mucus from L. fulica and P. canaliculata exhibited antioxidant and anti-inflammatory activities in different parameters. L. fulica mucus has higher total antioxidant (44.71 ± 2.11 mg AAE/g) and nitric oxide inhibitory activities (IC50 = 9.67 ± 0.31 µg/ml), whereas P. canaliculata mucus has better-reducing power activity (43.63 ± 2.47 mg AAE/g) and protein denaturation inhibition (IC50 = 0.60 ± 0.03 mg/ml). Histochemically, both species’ dorsal and ventral foot regions contained neutral and acid mucins in different quantities. In the dorsal region, the neutral mucins level in L. fulica (16.64 ± 3.46%) was significantly higher than that in P. canaliculata (11.19 ± 1.50%), while the acid mucins level showed no significant difference between species. Levels of both mucins in the ventral foot region of L. fulica (15.08 ± 3.97% and 10.76 ± 3.00%, respectively) were significantly higher than those of P. canaliculata (2.25 ± 0.48% and 2.71 ± 0.56%, respectively). This study revealed scientific evidence of the biological capacity of mucus from L. fulica and P. canaliculata as well as provided helpful information on the region of the foot which produces effective mucus

Molecular analysis of echinostome metacercariae from their second intermediate host found in a localised geographic region reveals genetic heterogeneity and possible cryptic speciation.

Echinostome metacercariae are the infective stage for humans and animals. The identification of echinostomes has been based until recently on morphology but molecular techniques using sequences of ribosomal RNA and mitochondrial DNA have indicated major clades within the group. In this study we have used the ITS2 region of ribosomal RNA and the ND1 region of mitochondrial DNA to identify metacercariae from snails collected from eight well-separated sites from an area of 4000 km2 in Lamphun Province, Thailand. The derived sequences have been compared to those collected from elsewhere and have been deposited in the nucleotide databases. There were two aims of this study; firstly, to determine the species of echinostome present in an endemic area, and secondly, to assess the intra-specific genetic diversity, as this may be informative with regard to the potential for the development of anthelmintic resistance and with regard to the spread of infection by the definitive hosts. Our results indicate that the most prevalent species are most closely related to E. revolutum, E. trivolvis, E. robustum, E. malayanum and Euparyphium albuferensis. Some sites harbour several species and within a site there could be considerable intra-species genetic diversity. There is no significant geographical structuring within this area. Although the molecular techniques used in this study allowed the assignment of the samples to clades within defined species, however, within these groupings there were significant differences indicating that cryptic speciation may have occurred. The degree of genetic diversity present would suggest the use of targeted regimes designed to minimise the selection of anthelmintic resistance. The apparent lack of geographic structuring is consistent with the transmission of the parasites by the avian hosts

Maximum Likelihood bootstrap consensus tree with 1000 bootstrap iterations of ITS2.

<p>Only values higher than 70% are shown.</p

Genetic diversity of <i>Euparyphium albuferensis</i> and <i>Echinostoma robustum/trivolvis/revolutum-like</i>. <i>E. malayanum</i> were all the same haplotype – i.e. no genetic diversity.

<p>Genetic diversity of <i>Euparyphium albuferensis</i> and <i>Echinostoma robustum/trivolvis/revolutum-like</i>. <i>E. malayanum</i> were all the same haplotype – i.e. no genetic diversity.</p

Variables associated with the populations used to test compliance with the “4× rule” for speciation.

<p>Variables associated with the populations used to test compliance with the “4× rule” for speciation.</p

Median-Joining network echinostomes based on the ND1 sequences.

<p>Different colours represent the geographic origins of clades/groups identified in this study. The genetic distances between the clades and their geographic spread are shown.</p

Metacercariae collected from different localities.

<p>Metacercariae collected from different localities.</p

Maximum Likelihood bootstrap consensus tree with 1000 bootstrap iterations based on the ND1 sequences and relevant GenBank sequences.

<p>Only values higher than 70% are shown.</p