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[Display omitted] • Wider distribution of invasive snails compared with native snails in the Limpopo River system. • cox 1 genetic data shows multiple lineages of invasive snails outside their native ranges. • More digenean species occurred in Pseudosuccinea columella than in the other snails. • The present xiphidiocercaria represents an unknown species of Orientocreadium. Invasive snails are associated with ecological problems in freshwater bodies worldwide. However, their impact on the transmission of digenean infections remain underreported. In the present study, 1708 specimens representing four snail species were sampled from four impoundments in the Limpopo River system in South Africa. Gyraulus chinensis (Planorbidae), Physella acuta (Physidae) and Pseudosuccinea columella (Lymnaeidae), which are invasive, were found in all the sampling sites. In contrast, the native lymnaeid Radix natalensis occurred at only one study site. Digeneans were observed only from R. natalensis (prevalence = 49%) and Ps. columella (prevalence = 23%). Morphological and genetic analyses revealed four digeneans: Fasciola nyanzae , Orientocreadium sp., Petasiger sp. and Patagifer vioscai. Pseudosuccinea columella was infected by the four digeneans while R. natalensis harboured only Orientocreadium sp. and Petasiger sp. Partial sequences of Orientocreadium sp. from the current study differed from congeners whose DNA data are available on GenBank, by p-distances of at least 1.84 and 2.2% for 28S and the internal transcribed spacer (ITS) rDNA, respectively. Phylogenetic analyses demonstrated that the present species is sister to Orientocreadium batrachoides. Genetic and phylogenetic data based on 28S and ITS rDNA suggested that Petasiger sp. from the present study and isolates of three unidentified Petasiger spp. from Kenya, Hungary and Australia, were representatives of the same species. This is the first known report of Orientocreadium , Petasiger and Patagifer from Ps. columella. The occurrence of F. nyanzae in Ps. columella indicates spillback from R. natalensis. These findings echo the concerns raised in previous studies about the potential role of Ps. columella in the amplification of digenean diseases in its introduced range. Phylogenetic analyses of partial sequences of the cytochrome c oxidase subunit 1 mitochondrial gene (cox 1) showed multiple lineages of Ps. columella in North and South America. Pseudosuccinea columella specimens from the present study belong to an invasive genotype that has spread globally and has been reported from Zimbabwe, Egypt, Portugal, Australia, Argentina, Colombia and New Mexico (USA). Physella acuta from the current study had a stronger genetic relationship with isolates from Canada and Iceland, than with isolates from other parts of Africa, suggesting several invasion routes into Africa. This is the first known DNA characterisation of G. chinensis from Africa. Phylogenetic reconstruction indicated multiple exit events of G. chinensis from Asia into Europe and Africa. South African isolates clustered in a recent branch containing isolates from the Czech Republic and Hong Kong, China. Considering the presence of invasive snails in all the sampling sites in the present study, it is necessary to investigate the factors that enhance their establishment and to monitor their effects on the native snail populations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recombinase Polymerase Amplification (RPA) is a simple and accurate tool for fast detection of Schistosoma mansoni DNA. • RPA targeting the S. mansoni mitochondrial minisatellite region (Sm MIT-RPA) can be used to detect infected snails. • Sm MIT-RPA detects S. mansoni early pre-patent infections in laboratory snails. • Sm MIT-RPA is a sensitive and specific tool for S. mansoni snail xenomonitoring. Improvements in diagnostics for schistosomiasis in both humans and snail hosts are priorities to be able to reach the World Health Organization (WHO) goal of eliminating the disease as a public health problem by 2030. In this context, molecular isothermal amplification tests, such as Recombinase Polymerase Amplification (RPA), are promising for use in endemic areas at the point-of-need for their accuracy, robustness, simplicity, and time-effectiveness. The developed recombinase polymerase amplification assay targeting the Schistosoma mansoni mitochondrial minisatellite region (Sm MIT-RPA) was used to detect S. mansoni DNA from both laboratory and field Biomphalaria snails. Laboratory snails were experimentally infected and used at one, seven, and 28 days post-exposure (dpe) to 10 S. mansoni miracidia to provide samples in the early pre-patent infection stage. Field samples of Biomphalaria spp. were collected from the Mucuri Valley and Jequitinhonha Valley regions in the state of Minas Gerais, Brazil, which are endemic for S. mansoni. The sensitivity and specificity of the Sm MIT-RPA assay were analysed and compared with existing loop-mediated isothermal amplification (LAMP), PCR-based methods, parasitological examination of the snails, and nucleotide sequencing. The Sm MIT-RPA assay was able to detect S. mansoni DNA in the experimentally infected Biomphalaria glabrata as early as one dpe to 10 miracidia. It also detected S. mansoni infections (55.5% prevalence) in the field samples with the highest accuracy (100% sensitivity and specificity) compared with the other molecular tests used as the reference. Results from this study indicate that the Sm MIT-RPA assay is a good alternative test to be used for snail xenomonitoring of S. mansoni due to its high sensitivity, accuracy, and the possibility of detecting early pre-patent infection. Its simplicity and portability also make it a suitable methodology in low-resource settings. [ABSTRACT FROM AUTHOR]

Marine snails (genus Littorina) have recently emerged as a model for speciation research, with repeated formation of different types of barriers to gene flow in contact zones between ecotypes and taxa. Inversion polymorphisms are found in an increasing number of species, including Littorina snails, and have been suggested to promote both local adaptation, ecotype formation and speciation, but their roles can vary. In Littorina , their role in later stages of speciation remains particularly unclear. A one-dimensional speciation continuum is frequently used to frame our understanding of the speciation process. However, a number of recent studies have argued that no single measure adequately summarises reproductive isolation and, therefore, the speciation process is best viewed in multiple dimensions. The many Littorina contact zones provide empirical data to illustrate how this principle can be applied. Speciation is a key evolutionary process that is not yet fully understood. Combining population genomic and ecological data from multiple diverging pairs of marine snails (Littorina) supports the search for speciation mechanisms. Placing pairs on a one-dimensional speciation continuum, from undifferentiated populations to species, obscured the complexity of speciation. Adding multiple axes helped to describe either speciation routes or reproductive isolation in the snails. Divergent ecological selection repeatedly generated barriers between ecotypes, but appeared less important in completing speciation while genetic incompatibilities played a key role. Chromosomal inversions contributed to genomic barriers, but with variable impact. A multidimensional (hypercube) approach supported framing of questions and identification of knowledge gaps and can be useful to understand speciation in many other systems. [ABSTRACT FROM AUTHOR]

Microbiota in intermediate hosts of human schistosomes play a significant role in various aspects of snail biology, such as growth and development. Understanding the potential impact of microbiota on snail–schistosome interactions and snail competence is crucial for future research and requires omics-based approaches. Successfully developing axenic and gnotobiotic models is a significant step that involves proper isolation of snail eggs, effective sterilization methods, suitable nutrition, and husbandry practices. And more axenic snail species are needed to cover diverse schistosome species. Advancing axenic and gnotobiotic snail systems and combining them with advanced technologies can offer insights into the role of snail microbiota and uncover intricate microbiota–snail and snail–parasite interactions, leading to the development of new strategies for controlling schistosomiasis. The microbiota in the intermediate snail hosts of human schistosomes can significantly affect host biology. For decades, researchers have developed axenic snails to manipulate the symbiotic microbiota. This review summarizes the characteristics of symbiotic microbes in intermediate snail hosts and describes their interactions with snails, affecting snail growth, development, and parasite transmission ability. We focus on advances in axenic and gnotobiotic technologies for studying snail–microbe interactions and exploring the role of microbiota in snail susceptibility to Schistosoma infection. We discuss the challenges related to axenic and gnotobiotic snails, possible solutions to address these challenges, and future research directions to deepen our understanding of snail–microbiota interactions, with the aim to develop microbiota-based strategies for controlling snail populations and reducing their competence in transmitting parasites. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) disrupts biological processes across taxa and at all levels of organisation. Despite growing interest in this globally pervasive sensory pollutant, its impact on colour-guided processes remains largely unexplored. This is especially concerning given the rapid transition in recent years away from narrow-spectrum lighting and towards broad-spectrum options such as white LEDs, which are rich in the short wavelengths of light to which many taxa are particularly sensitive. Camouflage is particularly likely to be disrupted by broader spectra of ALAN due to changes in conspicuousness in background matching prey, which may alter prey recognition in visually guided predators. We simulated natural intensities of moonlight with and without ALAN, using both broad-spectrum ('white') ALAN and ALAN filtered to remove the characteristic short (blue) wavelength peak of broad-spectrum LEDs to test whether filtering might mitigate their effects. We tested how exposure to these light treatments impacted predator-prey interactions, using the intertidal crab Carcinus maenas and contrasting colour morphs of the colour-polymorphic snail Littorina obtusata as a model system. Exposure to broad-spectrum ALAN reduced overall predation and reversed the pattern of colour-based prey selection observed under control conditions. Snails were 55 % less likely to be attacked under broad-spectrum ALAN than in control conditions, with likelihood decreasing over 70 % for yellow snails. Yellow snails were over 26 % more likely to be attacked than brown ones under control conditions, but brown snails were over 40 % more likely to be attacked than yellow ones under broad-spectrum ALAN. Exposure to filtered ALAN removed any significant colour-based difference in prey recognition. Our results demonstrate that spectral composition is a crucial aspect of ALAN as a sensory pollutant, capable of instigating profound changes in predator-prey interactions that could drive changes in population demography and increase morphological homogeneity in species that depend on colour polymorphism for camouflage. [ABSTRACT FROM AUTHOR]

Apple snails from the family Ampullariidae have become economically important due to several species mainly from the genus Pomacea being invasive. The heat shock proteins (HSPs), which are important molecular chaperones for species responding to various stresses, have been proved to play critical roles in adapting harsh environments in the invasive apple snails. The recent release of the genomes of Pomacea canaliculata , Pomacea maculata , Lanistes nyassanus , and Marisa cornuarietis has opened the opportunity for a comprehensive analysis of HSP superfamily in the ampullariids. We identified the number of HSP from P. canaliculata (PcaHSPs) was greater than that from the other three species. A total of 42 PcaHSPs were distributed on 12 chromosomes and were classified into the families of HSP90, HSP70, HSP60, HSP40, HSP20, and HSP10. Each family formed a monophyletic clade on the phylogenetic tree with strong support values, except for the HSP90 and HSP70 families. The RNA-seq data shows that most the PcaHSPs were of tissue-specific expression levels. Moreover, we identified more HSP genes with stronger transcription levels in response to heat than cold stress. Our findings are informative for future studies on stress adaptation and developing effective management strategies focusing on HSPs in invasive apple snails. [ABSTRACT FROM AUTHOR]

Land snails are sensitive to environmental changes and are valuable indicators of past changes. In this study, we analyzed 88,000 fossilized land snails from well-dated loess sequences in China spanning the past 20,000 years, and we detected two distinct phases of rapid compositional change. The first phase coincided with rapid climate changes associated with the last deglaciation (∼16.5–11 kyr BP), while the second phase (∼2.2 kyr BP) corresponded to the more gradual climate change of the late Holocene. The acceleration of snail compositional change since ∼2.2 kyr BP likely stems from human activities and related changes in agricultural land use. This unprecedented anthropogenic influence surpasses all other historical fluctuations over the past 20,000 years. Our findings underscore the significant role of human civilization in altering invertebrate communities, providing crucial insights into the ongoing human impact on Earth's ecosystems. • 88,000 fossil land snails from Chinese loess were analyzed to reconstruct compositional changes over 20,000 years. • Two distinct phases of rapid compositional change in the snail communities were detected. • Acceleration in snail compositional change since ∼2.2 thousand years ago implies human influence surpassing natural climate-driven rates. [ABSTRACT FROM AUTHOR]

While biogeographic patterns of free-living organisms are well documented, the biogeography of parasitic fauna remains largely unclear. Due to morphological similarities, parasites are often difficult to identify without the aid of molecular genetics, further complicating the interpretation of their biogeographic patterns. We investigated trematode parasites infecting the East Asian freshwater snail Semisulcospira libertina to understand their biogeography and to evaluate how molecular approaches influence the interpretation of biogeographic patterns of the trematode fauna. We identified 46 genetically delimited species from 19 morphologically distinguishable trematodes infecting S. libertina and found that their species richness was negatively correlated to latitude. We also found that potential definitive host (fishes) richness and host body size were positively correlated with trematode species richness, suggesting that host attributes are essential factors shaping the biogeographic pattern in trematodes. These trends were observed irrespective of species identification methods, demonstrating that classical morphological identification can also effectively identify the latitudinal gradient pattern in trematodes. We further detected the distance decay of similarity in trematode communities, although this trend was only detectable in the biogeographic dataset based on molecular identification. Our study showed that morphological identification sufficiently reflects the latitudinal richness gradient while molecular identification is essential to estimate accurate local species richness and increase the resolution of the large-scale pattern of population similarities in the trematode communities. [Display omitted] • Species richness of trematodes was negatively correlated with latitude. • The similarity in trematode communities decayed with geographical distance. • Host attributes can shape the biogeographic pattern in trematode richness. • Morphological and molecular identifications yielded similar biogeographic trends. [ABSTRACT FROM AUTHOR]

Polystyrene nanoparticles (PS NPs) released from plastic products have been demonstrated to pose a threat to leaf litter decomposition in streams. Given the multitrophic systems of species interactions, the effects of PS NPs through different exposure routes on ecosystem functioning remain unclear. Especially dietary exposure, a frequently overlooked pathway leading to toxicity, deserves more attention. A microcosm experiment was conducted in this study to assess the effects of waterborne and dietary exposure to PS NPs on the litter-based food chain involving leaves, microbial decomposers, and detritivores (river snails). Compared to waterborne contamination, dietary contamination resulted in lower microbial enzyme activities and a significantly higher decrease in the lipid content of leaves. For river snails, their antioxidant activity was significantly increased by 20.21%–69.93%, and their leaf consumption rate was significantly reduced by 16.60% through the dietary route due to the lower lipid content of leaves. Besides, the significantly decreased nutritional quality of river snails would negatively influence their palatability to predators. The findings of this study indicate that dietary exposure to PS NPs significantly impacts microbial and detritivore activities, thus affecting their functions in the detritus food chain as well as nutrient cycling. [Display omitted] • Impacts of PS NPs on detrital food chain were dependent on exposure routes. • A less lipid in leaves was due to reduced microbial activity by contaminated leaves. • Detritivores had severer oxidative stress and lower consumption by dietary exposure. • Dietary exposure to PS NPs led to the lowest quality of detritivore for its predator. [ABSTRACT FROM AUTHOR]

• We constructed three ensemble models with distinct variables combinations. • Appropriate environmental variables can effectively predict the habitats of O. hupensis. • The coupling of climatic and topographic variables is an effective modeling method. • High-risk areas for snails exhibit a concentration trend in Jiangsu Province. • "Distance to the nearest river" and "elevation" consistently emerged as crucial factors. Oncomelania hupensis (O. hupensis), the unique intermediate host for Schistosoma japonicum , exerts a substantial influence on the risk of schistosomiasis. Being amphibious freshwater snails, the growth, development, and reproductive distribution of O. hupensis are intricately tied to climatic environmental variables. This study aims to predict O. hupensis habitat risks along the Yangtze River in China, considering multiple environmental factors. Data pertaining to the distribution of O. hupensis, including both presence and absence records, with the Jiangsu section of the Yangtze River basin for the period 2017–2021, were retrieved from the Jiangsu Schistosomiasis Control Information Platform. Ten machine learning algorithms and an ensemble model were used to explore environmental drivers. Three datasets (Snail_CLIM, Snail_TOPO, and Snail_ALL) incorporating climatic and topographic variables were examined for their impact on model accuracy. We conducted validation using the AUC and TSS metrics. Moreover, we utilized the data from the 2022 snail field survey for model external validation. The findings demonstrate that snail_ALL, which incorporates both climatic and topographic variables, exhibits superior performance (ensemble model: sensitivity = 98.000, specificity = 95.960, AUC = 0.994). Among the ten model algorithms, Random Forest (RF) exhibited the highest degree of accuracy and stability (Snail_ALL: AUC = 1.000 ± 0.000, TSS = 0.985 ± 0.005). The key environmental factors affecting snail distribution included the distance to the nearest river, elevation, annual precipitation, and annual average pressure. High-risk areas manifested as two distinct concentrations: downstream of the Luhe District in Nanjing and at the confluence of Zhenjiang and Yangzhou. The results of 2022 field validation showed that over 90 % of the data points for snail breeding sites are concentrated in medium to high-risk areas. By selecting pertinent environmental variables and employing ensemble modeling techniques, we can accurately predict O. hupensis habitats. The resulting risk distribution map for snail habitats not only provides valuable insights but also serves as a guiding tool for targeted monitoring and control measures. The holds particular significance within the contest of the Yangtze River protection and restoration projects. [ABSTRACT FROM AUTHOR]

Fluoride (F-) exposure in organisms remains a significant concern due to its widespread presence and potential health implications. Investigating its detection and subsequent effects on behaviour in aquatic organisms like Lymnaea stagnalis provides valuable insights. Our study focused on elucidating the sensory pathways involved in F- detection and its impact on feeding and memory formation. We explored two potential detection mechanisms: direct flow across the integument onto neurons; and sensory input to the central nervous system (CNS) via the osphradium-osphradial ganglion-osphradial nerve pathway (snails use this system for olfactory sensation of multiple compounds). Injection of F- into snails did not alter feeding behaviour or central neuronal activity, suggesting that internalization might not be the primary detection mode. In contrast, severing the osphradial nerve abolished F-'s suppressive effects on feeding and memory formation, implicating the osphradial pathway in F- sensing and behavioural changes. This finding supports the idea that osphradial nerve signaling mediates the behavioural effects of F-. Our study underscores the importance of sensory pathways in F- detection and behavioural modulation in L. stagnalis. Understanding these mechanisms could provide critical insights into how organisms respond to and adapt to environmental chemical stressors like F-. • Acute fluoride exposure alters Garcia effect memory formation. • Severing the osphradial nerve blocks the effect of fluoride on memory formation. • The osphradium is involved in detecting fluoride and subsequent behavioural changes. [ABSTRACT FROM AUTHOR]

Mollusks, including snails, possess two chambered hearts. The heart and cardiomyocytes of snails have many similarities with those of mammals. Also, the biophysics and pharmacology of Ca, K, and Na ion channels resemble. Similar to mammals, in mollusks, the ventricular cardiomyocytes and K channels are often studied, which are selectively sensitive to antagonists such as 4-AP, E-4031, and TEA. Since the physiological properties of the ventricular cardiac cells of snails are well characterized, the enzymatically dissociated atrial cardiomyocytes of Cornu aspersum (Müller, 1774) were studied using the whole-cell patch-clamp technique for detailed comparisons with mice, Mus musculus. The incubation of tissues in a solution simultaneously containing two enzymes, collagenase and papain, enabled the isolation of single cells. Recordings in the atrial cardiomyocytes of snails revealed outward K+ currents closely resembling those of the ventricle. The latter was consistent, whether the voltage ramp or steps and long or short pulses were used. Interestingly, under identical conditions, the current waveforms of atrial cardiomyocytes in snails were similar to those of mice left ventricles, albeit the kinetics and the absence of inward rectifier K channel (I K1) activation. Therefore, the heart of mollusks could be used as a simple and accessible experimental model, particularly for pharmacology and toxicology studies. [Display omitted] • K+ currents were recorded for the first time in atrial cardiomyocytes of snails, Cornu aspersum. • Aurical and ventricular cardiomyocytes exhibit typical outward K+ currents. • Atrial K+ currents resemble those from mice left ventricle. • Inward rectifier K current (I K1) is absent in snails. [ABSTRACT FROM AUTHOR]

Species of Cotylurus Szidat, 1928 (Diplostomoidea: Strigeidae) are highly specialized digeneans that parasitize the gastrointestinal tract and bursa of Fabricius of water and wading birds. They have a three-host life cycle; the role of first intermediate host is played by pulmonate snails, while a wide range of water snails (both pulmonate and prosobranch) and leeches are reported as second intermediate hosts. Unfortunately, species richness, molecular diversity and phylogeny of metacercariae of Cotylurus spp. (tetracotyle) occurring in snails remain poorly understood. Thus, we have performed the parasitological and taxonomical examination of tetracotyles form freshwater snails from Poland, supplemented with adult Strigeidae specimens sampled from water birds. In this study we report our use of recently obtained sequences of two molecular markers (28S nuclear large ribosomal subunit gene (28S rDNA) and the cytochrome c oxidase subunit 1 (CO1) fragment), supplemented by results of a method of species delimitation (GMYC) and haplotype analysis to analyse some aspects of the ecology, taxonomy, and phylogeny of members of the genus Cotylurus. The provided phylogenetic reconstructions discovered unexpectedly high molecular diversity within Cotylurus occurring in snails, with clearly expressed evidence of cryptic diversity and the existence of several novel-species lineages. The obtained results revealed the polyphyletic character of C. syrius Dubois, 1934 (with three separate molecular species-level lineages) and C. cornutus (Rudolphi, 1809) Szidat, 1928 (with four separate molecular species-level lineages). Moreover, we demonstrated the existence of two divergent phylogenetical and ecological lineages within Cotylurus (one using leeches and other snails as second intermediate hosts), differing significantly in their life history strategies. [Display omitted] • Within Cotylurus existed two divergent phylogenetical and ecological lineages. • The lineages within Cotylurus sp. differing significantly in their routes of transmission. • Molecular analysis revealed high genetic diversity with evidence of cryptic species. [ABSTRACT FROM AUTHOR]

The widespread existence and persistence of antibiotics in the aquatic environment, and their extensive ecological risks, have attracted considerable attention. The objective of this study was to evaluate the occurrence and distribution of 25 antibiotics in environmental and biological samples from Poyang Lake Basin in China. SPE–HPLC–MS/MS was used to quantify the concentrations in different matrices. The total concentrations ranged from 144 to 933 ng/L in the water and 346 to 1154 ng/g in the sediment. In the spatial distribution analysis of this basin, the concentrations in the Ganjiang River were generally higher than those in Poyang Lake. The seasonal distribution in the wet and dry seasons showed comparatively higher concentrations during the dry season than the wet season. Additionally, antibiotics were found in various hydrophytes and animals, and the bioconcentration factor values followed the order: emergent plants > floating plants > submerged plants and benthic organisms > ducks > fish. Moreover, correlations among different matrices showed that antibiotics in viviparid snails were significantly positively correlated with those in ducks, and negatively correlated with those in carps, indicating the transmission relationship through the food chain. The results showed the trophic transfer of antibiotics in the food web and their potential environmental impacts on Poyang Lake Basin need constant attention. [Display omitted] • Antibiotics in Ganjiang River were higher than that in Poyang Lake. • K ow and pK a values of antibiotics were critical to their concentrations. • Viviparid snails were significantly correlated with ducks and carps. • Macrolides presented the main ecology risk factors to Poyang Lake Basin. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of arsenic stress on the gut microbiota of a freshwater invertebrate, specifically the apple snail (Pomacea canaliculata), and elucidate its potential role in arsenic bioaccumulation and biotransformation. Waterborne arsenic exposure experiments were conducted to characterize the snail's gut microbiomes. The results indicate that low concentration of arsenic increased the abundance of gut bacteria, while high concentration decreased it. The dominant bacterial phyla in the snail were Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteriota. In vitro analyses confirmed the critical involvement of the gut microbiota in arsenic bioaccumulation and biotransformation. To further validate the functionality of the gut microbiota in vivo , antibiotic treatment was administered to eliminate the gut microbiota in the snails, followed by exposure to waterborne arsenic. The results demonstrated that antibiotic treatment reduced the total arsenic content and the proportion of arsenobetaine in the snail's body. Moreover, the utilization of physiologically based pharmacokinetic modeling provided a deeper understanding of the processes of bioaccumulation, metabolism, and distribution. In conclusion, our research highlights the adaptive response of gut microbiota to arsenic stress and provides valuable insights into their potential role in the bioaccumulation and biotransformation of arsenic in host organisms. Arsenic, a widely distributed and carcinogenic metalloid, with significant implications for its toxicity to both humans and aquatic organisms. The present study aimed to investigate the effects of As on gut microbiota and its bioaccumulation and biotransformation in freshwater invertebrates. These results help us to understand the mechanism of gut microbiota in aquatic invertebrates responding to As stress and the role of gut microbiota in As bioaccumulation and biotransformation. [Display omitted] • Low concentration of As increased the gut microbiota abundance of P. canaliculata. • High concentration of As decreased the gut microbiota abundance of P. canaliculata. • Gut microbiota promote biotransformation and bioaccumulation of As in P. canaliculata. • The PBPK model effectively simulated the process of As accumulation and metabolism. [ABSTRACT FROM AUTHOR]

The transmission of Fasciola hepatica occurs only where there are -or recently were- aquatic or amphibious snails of the Lymnaeidae family, the intermediate host of this parasite. Direct detection of these snails is time-consuming and imprecise, hindering accurate and detailed mapping of transmission risk. To identify which microenvironmental factors could be used as proxies for the occurrence of the lymnaeid snail Galba viator , a major intermediate host in South America, a total of 183 1-m2 quadrants across diverse water bodies in an endemic area in Andean Patagonia were manually timed-searched for snails and microenvironmental variables were registered. Data was analyzed using a Bayesian hierarchical occupancy model that assessed the effects of the microenvironmental variables on the presence of snails while considering imperfect snail detection. The model estimated that G. viator predominantly inhabits shallow aquatic environments, in the presence of grasses, where snails of the genus Biomphalaria are also detected, and with scarce tree canopy cover. Physical factors affecting occupancy presumably act as proxies for the average water temperature, while the temperature at the time of sampling was found to affect snail detectability. The identified variables are easy, fast, and inexpensive to measure, and can complement management decisions and risk maps based on coarser remote-sensing data, particularly relevant in a context of growing resistance to anthelminthic drugs. • Occupancy model estimated effects of environmental variables on snail occurrence. • Higher water temperature at the time of sampling increases snail host detection. • Shade and water depth impair snail occurrence while grasses enhance it. • Factors affecting occupancy would act as proxies for the average water temperature. [ABSTRACT FROM AUTHOR]

• AG-Ag NPs and HG-Ag NPs were more toxic than their respective isolated extracts. • Both GP-Ag NPs treatments raised embryo mortality, with AG-Ag NPs being more toxic. • Snail embryos were more sensitive to GP-Ag NPs than newly-hatched snails. • GP-Ag NPs may be a sustainable and promising molluscicide alternative. Green silver nanoparticles (G-Ag NPs) have contributed to the development of ecological technologies with low environmental impact and safer for human health, as well as demonstrating potential for the control of vectors and intermediate hosts. However, knowledge about its toxicity in the early stages of gastropod development remains scarce. Therefore, the current study aimed to investigate the toxicity of G-Ag NPs synthesized from Croton urucurana leaf extracts in snail species Biomphalaria glabrata , which is an intermediate host for Schistosoma mansoni parasite. G-Ag NPs were synthesized using two types of plant extracts (aqueous and hydroethanolic) and characterized using multiple techniques. Bioassays focused on investigating G-Ag NPs and plant extracts were carried out with embryos and newly hatched snails, for 144 h and 96 h, respectively; toxicity was analyzed based on mortality, hatching, development inhibition, and morphological changes. Results have shown that both G-Ag NPs were more toxic to embryos and newly hatched snails than the investigated plant extracts. G-Ag NPs deriving from aqueous extract have higher molluscicidal activity than those deriving from hydroethanolic extract. Both G-Ag NPs induced mortality, hatching delay, development inhibition, and morphological changes (i.e., hydropic embryos), indicating their molluscicidal activities. Moreover, embryos were more sensitive to G-Ag NPs than newly hatched snails. Thus, the toxicity of G-Ag NPs to freshwater snails depends on the type of extracts and the snail's developmental stages. These findings can contribute to the development of green nanobiotechnologies applicable to control snails of medical importance. [Display omitted] [ABSTRACT FROM AUTHOR]

• Molecular support of S. mansoni / B. glabrata compatibility. • Non clonal snail lines with same genetic background. • 328 genes differentially regulated in resistant vs susceptible phenotypes. • Lipid compounds differed in resistant vs susceptible phenotypes. Biomphalaria glabrata is a freshwater snail and the obligatory intermediate host of Schistosoma mansoni parasite, the etiologic agent of intestinal Schistosomiasis, in South America and Caribbean. Interestingly in such host-parasite interactions, compatibility varies between populations, strains or individuals. This observed compatibility polymorphism is based on a complex molecular-matching-phenotype, the molecular bases of which have been investigated in numerous studies, notably by comparing between different strains or geographical isolates or clonal selected snail lines. Herein we propose to decipher the constitutive molecular support of this interaction in selected non-clonal resistant and susceptible snail strain originating from the same natural population from Brazil and thus having the same genetic background. Thanks to a global RNAseq transcriptomic approach on whole snail, we identified a total of 328 differentially expressed genes between resistant and susceptible phenotypes among which 129 were up-regulated and 199 down-regulated. Metabolomic studies were used to corroborate the RNAseq results. The activation of immune genes and specific metabolic pathways in resistant snails might provide them with the capacity to better respond to parasite infection. [ABSTRACT FROM AUTHOR]

Trematodes belonging to the family Echinostomatidae are food-borne parasites which cause echinostomiasis in animals and humans. This is a global public health issue, particularly in East and Southeast Asia. A method to detect the infective stage of Echinostomatidae species is required to prevent transmission to humans. In this study, a loop-mediated isothermal amplification coupled with a lateral flow dipstick (LAMP-LFD) assay was developed for visual detection of the metacercarial stage in edible snails of the genus Filopaludina from local markets in Thailand. The LAMP-LFD method can be performed within 70 min at a consistent temperature of 66 °C, and the results can be interpreted with the naked eye. The detection limits of the assay using Echinostoma mekongi , E. macrorchis , E. miyagawai and Hypoderaeum conoideum genomic DNA were equal between the four species at 50 pg/μL. A specificity evaluation demonstrated that the LAMP-LFD assay had no cross-reaction with another parasite (Thapariella species) or with the snail host species (Filopaludina martensi martensi , F. sumatrensis speciosa , and F. s. polygramma). Clinical test assessments were compared to microscopic examination in 110 edible snail samples. The clinical sensitivity and specificity of the tests were 84.62 % and 100 %, respectively, with a strong level of agreement based on the kappa statistic and the results of both methods were not significantly different (p > 0.05) per McNemar's test. The test successfully developed in this study may be useful for the detection of the metacercarial stage in edible snails for epidemiological investigations, control, surveillance, and to prevent future echinostomiasis health issues. • The assay can amplify DNA of four Echinostomatidae species in a single tube. • The results can be obviously visualized with the naked eye. • The assay could be utilized to diagnose Echinostomatidae infection in edible snail. • This study is the first LAMP-LFD assay for Echinostomatidae detection. [ABSTRACT FROM AUTHOR]

(Eco)toxicological studies frequently evaluate the effects of chemicals in one life stage of organisms, but the use of these outcomes can only partially estimate populational effects. In this regard, multi- and/or transgenerational studies should be performed in order to provide information on contaminant effects in a populational functioning context. The present review aimed to summarize and critically evaluate the current knowledge regarding multi- and/or transgenerational effects of traditional and emerging environmental chemicals on mollusks. Results showed that these kinds of studies were performed in aquatic mollusks (bivalve and gastropod), being Gastropoda the mollusk Class most frequently studied. Additionally, freshwater species and multigenerational studies were more common for this class. For the Bivalvia class, only marine species were evaluated, and transgenerational exposure was more commonly assessed. The effects were reported for 15 species, highlighting the marine bivalves Crassostrea gigas and Saccostrea glomerata , and the freshwater gastropod Lymnaea stagnalis. Multi- and transgenerational effects were described for 8 environmental chemical groups, mainly metals, pesticides, and pharmaceuticals. In general, multi- and transgenerational exposure induced biometric, developmental, and reproductive impairments in mollusks, indicating that environmental chemicals might lead to generational impairments, reduced population growth and reproductive capacity, and decreased fitness. The current study indicated that bivalves and gastropods are suitable organism models to assess the multi- and transgenerational adverse effects induced by traditional and emerging environmental chemicals. [Display omitted] • State-of-the-art review on multi- and transgenerational studies with mollusks. • Studies were performed only with aquatic bivalves and gastropods. • Chemicals induced biometric, developmental, and reproductive changes in mollusks. • Multi- and transgenerational exposures decreased fitness, reproduction, and growth. • Bivalves and gastropods are suitable sentinel species to assess pollution. [ABSTRACT FROM AUTHOR]

• Adverse effects of glyphosate, AMPA and mixed solution were evaluated on L. stagnalis. • Glyphosate, AMPA, and the mixed solution caused genomic damage. • Adverse effects were noted on somatic growth and egg production. • Glyphosate at the EFSA acceptable daily intake of 0.500 µg/mL induce adverse effects. Aminomethylphosphonic acid (AMPA) is the main metabolite in the degradation of glyphosate, a broad-spectrum herbicide, and it is more toxic and persistent in the environment than the glyphosate itself. Owing to their extensive use, both chemicals pose a serious risk to aquatic ecosystems. Here, we explored the genotoxicological and physiological effects of glyphosate, AMPA, and the mixed solution in the proportion 1:1 in Lymnaea stagnalis , a freshwater gastropod snail. To do this, adult individuals were exposed to increasing nominal concentrations (0.0125, 0.025, 0.050, 0.100, 0.250, 0.500 µg/mL) in all three treatments once a week for four weeks. The genotoxicological effects were estimated as genomic damage, as defined by the number of micronuclei and nuclear buds observed in hemocytes, while the physiological effects were estimated as the effects on somatic growth and egg production. Exposure to glyphosate, AMPA, and the mixed solution caused genomic damage, as measured in increased frequency of micronuclei and nuclear buds and in adverse effects on somatic growth and egg production. Our findings suggest the need for more research into the harmful and synergistic effects of glyphosate and AMPA and of pesticides and their metabolites in general. [ABSTRACT FROM AUTHOR]

Despite the importance of fish-borne trematodes of the family Opisthorchiidae as causative agents of human liver fluke disease, studies on these parasites outside Asia are relativally scarce. In South America, human focus of amphimerosis is known in Ecuador since the mid-20th century, and Amphimerus spp. have also been reported in wild and domestic mammals. Nevertheless, the knowledge on the snails that act as the first intermediate host of these potentially zoonotic parasites are scarce. Herein, a new cercaria of the pleurolophocercous morphotype found in the freshwater snail Idiopyrgus souleyetianus from Brazil was subjected to morphological and molecular studies. Multigene phylogenetic analyses based on 28S, 5.8S-ITS-2 and Cox-1 sequences enabled the identification of Amphimerus sp., a species distinct from that reported in humans from Ecuador. This cercariae was morphologically compared with other opisthorchiid cercariae known. The possible occurrence of human amphimerosis in Brazil is discussed. [Display omitted] • Cercaria of Amphimerus sp. is reported for the first time in Brazil. • Idiopyrgus souleyetianus is an intermediate host of liver fluke. • Genetic data (28S, ITS, Cox-1) supported the parasite identification. • Cox-1 sequences suggest that the Brazilian and Ecuadorian isolates are distinct species. [ABSTRACT FROM AUTHOR]

Bifenthrin (BF) is ubiquitous in aquatic environments, and studies have indicated that environmental concentrations of BF could cause neurotoxicity and oxidative damage in fish and decrease the abundance of aquatic insects. However, little information is available on the toxicity of BF in freshwater benthic mollusks. Bellamya aeruginosa (B. aeruginosa) is a key benthic fauna species in aquatic ecosystems, and has extremely high economic and ecological values. In this study, larval B. aeruginosa within 24 h of birth were exposed to 0, 30 or 300 ng/L of BF for 30 days, and then the toxic effects from molecular to individual levels were comprehensively evaluated in all the three treatment groups. It was found that BF at 300 ng/L caused the mortality of snails. Furthermore, BF affected snail behaviors, evidenced by reduced crawling distance and crawling speed. The hepatopancreas of snails in the two BF exposure groups showed significant pathological changes, including increase in the number of yellow granules and occurrence of hemocyte infiltration, epithelial cell thinning, and necrosis. The levels of ROS and MDA were significantly increased after exposure to 300 ng/L BF, and the activities of two antioxidant enzymes SOD and CAT were increased significantly. GSH content decreased significantly after BF exposure, indicating the occurrence of oxidative damage in snails. Transcriptomic results showed that differentially expressed genes (DEGs) were significantly enriched in pathways related to metabolism and neurotoxicity (e.g., oxidative phosphorylation and Parkinson disease), and these results were consistent with those in individual and biochemical levels above. The study indicates that environmental concentration of BF results in decreased survival rates, sluggish behavior, histopathological lesions, oxidative damage, and transcriptomic changes in the larvae of B. aeruginosa. Thus, exposure of larval snails to BF in the wild at concentrations similar to those used in this study might have adverse consequences at the population level. These findings provide a theoretical basis for further assessing the ecological risk of BF to aquatic gastropods. [Display omitted] • Bifenthrin changed behaviors of larval Bellamya aeruginosa and led to mortality. • Exposure to Bifenthrin caused a pathological change in hepatopancreas. • Exposure with Bifenthrin led to oxidative damage and transcriptomic changes. [ABSTRACT FROM AUTHOR]

• Infection rate of B. troschelii by trematoda O. felineus increased with increasing of water temperature. A possible increase in opisthorchiid infection of snails under global warming must be taken into account when planning epidemiological measures. • The autumn-winter diapause in snails life causes a "delay" in the development of intramolusken stages of opisthorchiid. Cercariae of O. felineus from B. troschelii in Western Siberia emergence only the next year after snail's infection. • Сomplete hibernation of B. troschelii In Western Siberia is observed at 10 °C. • The prevalence of O. felineus infection in B. troschelii under experimental conditions was significantly higher (30–45 %), compare with 0.19 % in natural infection survey. Opisthorchiasis is one of the most serious trematodiases in Russia, where the world's largest focus is located in the Ob basin. Temperature is an important factor affecting the metabolism of cold-blooded animals. It determines the development of the causative agent of opisthorchiasis, Opisthorchis felineus , and the success of infection of an intermediate host, the snail Bithynia troschelii. In the present study, the effect of water temperature on the development of the liver fluke O. felineus in the host snail was assessed, as was the temperature threshold at which B. troschelii hibernation initiates. Adult uninfected B. troschelii individuals collected from natural bodies of water were infected with O. felineus and maintained at different temperatures of water (18–30 °C, intervals of 3 °C) in the laboratory. Each snail was fed with embryonated uterine eggs of O. felineus at 24 °C. O. felineus infection in snails was detected using polymerase chain reaction (PCR) using specific primers. The prevalence of O. felineus infection in B. troschelii depends on the water temperature in which the snails are maintained. The highest infection rate of 45.2 % ± 12.1 % was observed at 27 °C (p ≥ 0.1). The longest lifespan of infected and uninfected B. troschelii was recorded at water temperatures of 24 and 27 °C. The snails were more successfully infected at the beginning of the warm season. Among the infected individuals, the majority (up to 85 %) were large snails. Cercarial shedding was not detected in experimentally infected snails. Apparently, this is due to the natural physiological state of Bithynia snails during the autumn–winter diapause, when opisthorchiids development in snails stops. At 10 °C, complete hibernation of all B. troschelii snails was observed, and infection by the trematodes became impossible. The highest prevalence of infection was recorded at 27 °C, suggesting that during climate warming, an increase in opisthorchiid infection of snails may occur, which must be considered when epidemiological measures are planned. [Display omitted] [ABSTRACT FROM AUTHOR]

Sun Hole, a small fissure cave on the north side of Cheddar Gorge, Somerset, is best known as the site where late Upper Palaeolithic artefacts are associated with human and other mammal remains that immediately pre-date the Lateglacial interstadial. These remains from the upper levels (Unit I) overlie sediments (Unit II) that are thought to have accumulated during a full glacial period, below which are sediments (Unit III) attributed to an interglacial stage. The extinct land snail Retinella (Lyrodiscus) sp., which in Britain was only known from the Hoxnian Stage, had previously been recovered from Unit III. The interglacial at the base of the sequence was therefore assigned to the Hoxnian Stage (Marine Isotope Stage (MIS) 11, 424–374 kyr). Here we provide additional analyses of samples from Unit III, which as well as containing further Retinella (Lyrodiscus), also yielded a specimen of Monachoides incarnatus , its first record from the British Pleistocene. An associated assemblage of small mammals included a few that are rare in the British Pleistocene, such as birch mouse (Sicista cf. betulina) and garden dormouse (Eliomys quercinus). The vole Lasiopodomys gregaloides and the shrew Sorex (Drepanosorex) savini do not occur as late as the Hoxnian and therefore suggest an older age in the early Middle Pleistocene. The record from Sun Hole therefore has parallels with the well-known sequence from the upper Calcareous Member in the nearby cavern system at Westbury-sub-Mendip. [ABSTRACT FROM AUTHOR]

This manuscript was conducted to spotlight the toxic effect of two sub-lethal concentrations of Methomyl (Copter) LC 20 (0.075 g/L) and LC 40 (0.180 g/L) on some biochemical parameters and histological alterations for land snail Monacha Cartusiana (Muller, 1774). Land snails belong to the class Gastropoda and Phylum Mollusca. This study cleared that both the used concentrations (of Copter) caused a significant increase for activities of three enzymes: alkaline phosphatase (ALP), alanine amino transaminase (ALT), and Aspartate amino transaminase (AST) after 24, 48, and 72 h from exposure starting. In contrast, a total protein (TP) activity decreased at exposure for two concentrations at all lethality periods. Both concentrations of Copter (0.0.75 g/L and 0.180 g/L) have shown histological changes for land snail tissues after 96 h of exposure; digestive gland, hermaphrodite gland, foot, and mantle. Degeneration, rupture, and vacuolization for digestive cells have been shown; furthermore, hemolytic infiltration in connective tissue will be recognized for the digestive gland. The Oocyte and sperm show degenerated with deformation in the connective tissue of the hermaphrodite gland. Likewise, deformation in the muscle fiber layer of the foot in the land snail distorts the epidermis and mucus gland suffering from necrosis. Moreover, mantle shows rapture in epidermis layer, deformed in muscle fiber layer, and vacuolization and necrosis take place in mucus gland. [ABSTRACT FROM AUTHOR]

Fasciola hepatica is a worldwide emerging and re-emerging parasite heavily affecting several regions in South America. Some lymnaeid snail species of American origin are among the major hosts of F. hepatica worldwide. Recent paleoparasitological findings detected its DNA in a 2300-year-old sample in Patagonia, countering the common hypothesis of the recent arrival of F. hepatica in the Americas during European colonization. Thus, the theory of an initial introduction in the 1500s can no longer be sustained. This article discusses how it was possible for F. hepatica to reach and spread in the Americas in relation to the availability and compatibility of hosts through natural and incidental introductions. Our study will serve to better understand the ongoing Neotropical scenario of fasciolosis. The possible ways in which Fasciola hepatica arrived in the Americas are discussed. F. hepatica interaction with American lymnaeid snails dates back long before the 1500s and is more ancient than European colonization. Adaptation during the spread of F. hepatica favored strong compatibility with amphibious lymnaeids. Ancient circulation of F. hepatica in the Americas is consistent with both hyperendemic human and extended cattle transmission today. [ABSTRACT FROM AUTHOR]

• A clonorchiasis epidemic model with time delays is proposed. • The clonorchiasis transmission case in Guangxi Province, China is studied. • The results are beneficial to the control of clonorchiasis for Guangxi. • The analysis and simulation methods are also applicable to other vector-borne diseases models. Clonorchiasis is a serious food borne parasitic disease caused by clonorchis sinensis that is transmitted via snails to freshwater fish, and then to humans and other mammals. Based on the life cycle clonorchis sinensis, we present a mathematical model of clonorchiasis with three time delays which represent the maturation period of metacercaria developing adult flukes within human host, the period of eggs developing cercariae within snail host and the period of cercariae developing metacercaria within fish host.The basic reproduction number R 0 for this model is introduced. We establish a threshold type result on the global dynamics in terms of R 0. More precisely, the disease-free equilibrium is globally attractive if R 0 < 1 ; while the disease is uniformly persistent if R 0 > 1. Considering the above-mentioned periods can also be modelled by introducing the corresponding exposed classes, we also study the dynamical behavior of the corresponding model without delays. Numerically, we study the clonorchiasis transmission case in Guangxi Pronvince, China. Some control strategies are provided to prevent clonorchiasis spread in Guangxi by numerical analysis. [ABSTRACT FROM AUTHOR]

• This study evaluated nucleic acid amplification techniques for diagnosing Schistosoma mansoni infections • Pooled sensitivity was 89.79% and specificity was 87.70% for human samples • qPCR showed modest sensitivity (68.75%) and high specificity (92.45%) for rodents • PCR and nPCR assays showed sensitivity of 90.06% and specificity of 85.51% for snails Schistosomiasis is a parasitic disease caused by hematodes of genus Schistosoma. This review evaluated the available nucleic acid amplification techniques for diagnosing S. mansoni infections in humans, intermediate host snails, and presumed rodent reservoirs. Sensitivity, specificity, diagnostic odds ratio (DOR), and 95% CI were calculated based on available literature. The potential of PCR, nPCR, PCR-ELISA, qPCR, and LAMP was compared for diagnosing S. mansoni infections. A total of 546 published records were identified. Quality assessment by QUADAS-2 revealed an uncertain risk in most studies, and 21 references were included in the final. For human samples, the four nucleic acid amplification techniques showed an overall sensitivity of 89.79% (95% CI: 83.92%-93.67%), specificity of 87.70% (95% CI: 72.60%-95.05%), and DOR of 37.73 (95% CI: 21.79-65.33). LAMP showed the highest sensitivity, followed by PCR-ELISA, PCR, and qPCR, while this order was almost reversed for specificity; qPCR had the highest AUC. For rodent samples, qPCR showed modest sensitivity (68.75%, 95% CI: 43.32%-86.36%) and high specificity (92.45%, 95% CI: 19.94%-99.83%). For snail samples, PCR and nPCR assays showed high sensitivity of 90.06% (95% CI: 84.39%-93.82%) and specificity of 85.51% (95% CI: 54.39%-96.69%). Nucleic acid amplification techniques had high diagnostic potential for identifying S. mansoni infections in humans. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coinfection does not decrease prevalence of a dominant parasite. • Co-exposure slows the development time of the late arriving dominant parasite. • Despite slower development, the dominant parasite has higher reproductive output when in a co-exposed host. Within a single organism, numerous parasites often compete for space and resources. This competition, together with a parasite's ability to locate and successfully establish in a host, can contribute to the distribution and prevalence of parasites. Coinfection with trematodes in snail intermediate hosts is rarely observed in nature, partly due to varying competitive abilities among parasite taxa. Using a freshwater snail host (Biomphalaria glabrata), we studied the ability of a competitively dominant trematode, Echinostoma caproni , to establish and reproduce in a host previously infected with a less competitive trematode species, Schistosoma mansoni. Snails were exposed to S. mansoni and co-exposed to E. caproni either simultaneously or 1 week, 4 weeks, or 6 weeks post S. mansoni exposure. Over the course of infection, we monitored the competitive success of the dominant trematode through infection prevalence, parasite development time, and parasite reproductive output. Infection prevalence of E. caproni did not differ among co-exposed groups or between co-exposed and single exposed groups. However, E. caproni infections in co-exposed hosts took longer to reach maturity when the timing between co-exposures increased. All co-exposed groups had higher E. caproni reproductive output than single exposures. We show that although timing of co-exposure affects the development time of parasite transmission stages, it is not important for successful establishment. Additionally, co-exposure, but not priority effects, increases the reproductive output of the dominant parasite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Exceptional preservation of a land snail in amber captures 99-million-year-old live birth event. • Viviparity in land snails is revealed to be 80 million years older than so far known in fossil record. • Viviparity is interpreted as birth strategy of choice during predator hungry mid-Cretaceous era. • Fossilized Burmese amber reveals new species of terrestrial snail, Cretatortulosa gignens n. sp. • Ct scans of mother land snail reveal marshmallow-like body, slime and 5 neonates in Burmese amber. When seldom life history events serendipitously get documented by exceptional preservation in the fossil record, a unique telescopic opportunity arises for interpreting fossils within their paleoenvironment as well as for understanding ancestral relationships of current life forms. We present a rare glimpse of live birth by a terrestrial mother snail, incidentally, engulfed by amber as she released her young in a tropical forest during the mid-Cretaceous (early Cenomanian). The exceptional finding featuring the preservation of a snail's 99-million-year-old soft-body together with five neonate shells represents the earliest known fossilized incidence of viviparity in a terrestrial snail. Based on high-resolution photographs and µCT scans, we describe the mother snail as a new species of cyclophoroid, Cretatortulosa gignens sp. nov. Our finding provides remarkable perspectives for interpreting gastropod evolution 80 million years earlier than the fossil record has known up to now. It shows that viviparity was already a relevant reproductive strategy in the Cretaceous, probably increasing the offspring's survival chance in a predator-lurking tropical forest. [ABSTRACT FROM AUTHOR]

Recent technical innovations are revealing surprising patterns in mollusc shell pigmentation, such as an unexpectedly modest role for melanins and rapid divergences in the mix of pigments used to achieve similar colour patterns. The elucidation of the molecular genetic basis of shell pigmentation has been slow, probably because of the high genome complexity of gastropods and bivalves. Recent work within the old field of evolutionary ecology of shell pigmentation allows a greater role for the analysis of large-geographic-scale patterns (sometimes employing citizen-science data), as well as experimental field studies. However, the field remains dominated by land snails as model organisms, while colour pattern evolution in marine gastropods and bivalves, particularly those not exposed to visual predators, remains mysterious. [ABSTRACT FROM AUTHOR]

The Atlantic Forest is a highly fragmented biodiversity hotspot, which in Argentina is represented by the Paranaense Forest, covering a wide area of the province of Misiones. In conservation studies, groups of vertebrates, plants and arthropods are generally used together but other invertebrates scarcely used. In the present work, we aim to provide information on new species of freshwater gastropods, from protected and unprotected areas. Specimens were collected in a protected area (Yabotí Biosphere Reserve) and in two unprotected areas (Alba Posse city and Centro de Investigaciones Antonia Ramos -CIAR-). The shell, radula, internal anatomy and the molecular information of the partial sequence of mitochondrial cytochrome c oxidase subunit I (COI) were analysed. The phylogenetic trees were obtained using Maximum Likelihood and Bayesian Inference analyses. Altogether, the anatomical, shell, and genetic studies allow us to differentiate six new species of the genus Potamolithus from the others present in Argentina and the surrounding areas. These new species raise the number of freshwater gastropods for the malacological province Río Uruguay to 64. Three of the new species have been found within a protected area, while other three at unprotected areas. The presence of invasive species, such as Limnoperna fortunei (Dunker 1857) and Melanoides tuberculata (Müller, 1774), as well as the possible creation of a hydroelectric dam, may modify the environment inhabited by the new endemic fauna. [ABSTRACT FROM AUTHOR]

Snail mucus is rich in proteins and polysaccharides, which has been proved to promote wound healing in mice in our previous research. The aim of this study was to investigate the effective component in snail mucus that can exert the wound healing potential and its structural characterization. Here, the glycoprotein from the snail mucus (SM1S) was obtained by DEAE-Sepharose Fast Flow and Sephacryl S-300 columns. The structural characteristics of SM1S were investigated via chromatographic techniques, periodic acid oxidation, FT-IR spectroscopy and NMR spectroscopy. Results showed that SM1S was a glycoprotein with a molecular weight of 3.8 kDa (83.23 %), consists of mannose, glucuronic acid, glucose, galactose, xylose, arabinose, fucose at a ratio of 13.180:4.875:1043.173:7.552:1:3.501:2.058. In addition, the periodic acid oxidation and NMR analysis showed that SM1S contained 1,6-glycosidic bonds, and might also contain 1 → 4 and 1 → 2 glycosidic or 1 → 3 glycosidic bonds. Furthermore, the migration experiment of human skin fibroblasts in vitro suggested that SM1S had a good effect to accelerate the scratch healing of cells. This study suggested that SM1S may be a prospective candidate as a natural wound dressing for the development of snail mucus products. [Display omitted] [ABSTRACT FROM AUTHOR]

Fossil land snails in aeolian sediments are useful for reconstructing past environments, but quantitative knowledge about their geographical and climatic distribution is limited. We conducted a systematic survey of snails in 402 surface soil samples from China, spanning the climatic range from cold temperate to subtropical. The dominant snail species include Vallonia tenera , Gastrocopta armigerella , Pupilla aeoli , Cathaica richthofeni , Punctum orphana , Opeas striatissimum , and Macrochlamys angigyra. Using the Maximum Entropy model, we determined the geographical distribution of individual species. M. angigyra and O. striatissimum are abundant mainly in warm-temperate and subtropical regions, while P. aeoli and V. tenera occurred mainly in semi-arid regions. Quantitative estimates of the optimal climatic parameters and tolerance ranges for the snail species were obtained using weighted averaging. Cold aridiphilous species like V. tenera (MAT: ∼5.1–12.5 °C, MAP: ∼400–640 mm) and P. aeoli (∼6.2–10.9 °C, ∼390–580 mm) demonstrate greater adaptability and tolerance to lower temperatures compared to the thermo-humidiphilous M. angigyra (∼10.0–15.8 °C, ∼500–1100 mm), and O. striatissimum (∼9.9–15.3 °C, ∼490–960 mm). These quantitative climate ranges and geographical distributions can be applied to Quaternary snails in China to accurately quantify past climates. • The mapping of snail geographic distribution reveals their climate sensitivities. • The suitable climate ranges for key snail species has been quantifies. • The study highlights climatic indicators for reconstructions using snail fossils. [ABSTRACT FROM AUTHOR]

Lymnaeid snails are some of the most widespread snails and are the first intermediate host of trematode parasites that affect human and livestock health. A full understanding of the genetic relationship of hosts and parasites is of paramount importance for effective parasite management. The present study assessed the prevalence of trematode larvae in lymnaeid snails and examined the genetic diversity of these snails collected across Thailand. We collected 672 lymnaeid snails from 39 locations in 22 provinces of six regions in Thailand. Subsequently, cercarial infection in the snails was observed by using the shedding method. Lymnaeid snails released 5 types of trematode cercariae, namely, xiphidiocercariae, echinostome cercariae I, echinostome cercariae II, furcocercous cercariae, and strigea cercariae. The phylogenetic analysis based on ITS2 and 28S rDNA sequences revealed 5 cercaria types assigned to four trematode families, of which two belong to the group of human intestinal flukes. Combination of shell morphology and sequence analysis of the mitochondrial COI and 16S rDNA genes, the lymnaeid snails were classified into two species, Radix rubiginosa and Orientogalba viridis. Moreover, the combined dataset of mtDNA genes (COI + 16S rDNA) from R. rubiginosa and O. viridis revealed 32 and 15 different haplotypes, respectively, of which only a few haplotypes were infected with cercariae. The genetic diversity and genetic structure revealed that R. rubiginosa and O. viridis experienced a bottleneck phenomenon, and showed limited gene flow between populations. Population demographic history analyses revealed that R. rubiginosa and O. viridis experienced population reductions followed by recent population expansion. These findings may improve our understanding of parasite–lymnaeid evolutionary relationships, as well as the underlying molecular genetic basis, which is information that can be used for further effective control of the spread of trematode disease. [Display omitted] • We present the genetic relationship between lymnaeid snails and digenean trematodes in Thailand. • Radix rubiginosa and Orientogalba viridis released 5 types of cercariae. • Population analysis revealed a bottleneck and limited migration in R. rubiginosa and O. viridis. • Demographic history analysis showed that lymnaeid snails experienced population expansions in Thailand. [ABSTRACT FROM AUTHOR]

In order to investigate and study the species and distribution of freshwater snails in Ordos area of Inner Mongolia, as well as the trematode infection in different periods, and to provide a scientific basis for the effective prevention and control of livestock trematodiasis. In this paper, freshwater snails distributed in Ordos were widely collected for morphological identification, and PCR amplification of freshwater snails COI gene and ITS2 gene was carried out with the help of molecular biology. At the same time, microscopic examination was used to observe the trematode infection of freshwater snails in two different periods from May to July and July to September, and the molecular biology of the trematodes was identified. The results showed that the 1796 freshwater snails collected belonged to two orders, three families and four genera, i.e. Bellamya, Radix, Galba, and Gyraulus. Microscopic examination of snails showed that the infection rate of trematode larvae from July to September was significantly higher than that from May to July. The collected trematodes were identified as five species, namely Cotylurus marcogliesei , Fasciola hepatica , Fasciola gigantica , Paramphistomum cervi, and Parastrigea robusta. The combination of freshwater snail species in Ordos and the infection of trematode in snails showed that a large number of freshwater snails were infected with trematodes, especially from July to September, when there is more rain and suitable climate, which causes serious harm to local livestock. [Display omitted] • There are a large number of freshwater snails in the Ordos area. • The trematodes are abundant in Ordos. • The trematode positivity rate of freshwater snails may be seasonal. • There were no previous similar reports in the Ordos region, and this study fills this gap. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) accumulation in rocky shore organisms has limited knowledge. This study investigated MPs accumulation in filter-feeding oysters, herbivorous limpets and carnivorous snails to assess their performance as sentinel species in the MPs trophic transfer. The samples were obtained along a contamination gradient in the Santos Estuarine System, Brazil. All three studied species showed MPs concentrations related to the contamination gradient, being the oysters the species that showed the highest levels, followed by limpets and snails (average of less and most contaminated sites of 1.06–8.90, 2.28–5.69 and 0.44–2.10 MP g−1, respectively), suggesting that MPs ingestion rates are linked to feeding habits. MPs were mainly polystyrene and polyacetal. The polymer types did not vary among sites nor species. Despite minor differences in percentages and diversity of size, shape, and color classes, the analyzed species were equally able to demonstrate dominance of small, fiber, transparent, black and blue MPs. Thus, oysters, limpets, and snails are proposed as sentinels of MPs in monitoring assessments. [Display omitted] • Oysters accumulated more microplastics (MPs) than limpets and snails. • Filter-feeders accumulated more MPs than herbivores and carnivorous. • All species similarly reflected the known contamination gradient. • Minor differences in MP types were seen spatially and among species. • Oysters, limpets and snails can be used as sentinels of MPs contamination. [ABSTRACT FROM AUTHOR]

To assess the blending effect of field snails with grass carp muscle, the effects of paramyosin (PM) and actomyosin (AM) with different mixture ratios on the gel properties of the binary blend system were investigated in our work. The purified PM from field snail muscle was about 95 kDa on SDS-PAGE. Its main secondary structure was α-helix, which reached to 97.97 %. When the amount of PM increased in the binary blend system, their rheological indices and gel strength were improved. The water holding capacity (WHC) increased to 86.30 % at a mixture ratio of 2:8. However, the WHC and the area of immobile water (P 22) dramatically decreased, and the area of free water (P 23) increased when the mixture ratio exceeded 4:6. The low level of PM in binary blend system promoted the formation of a homogenous and dense gel network through non-covalent interactions as observed results of SEM and FTIR. When there were redundant PM molecules, the development of heterostructure via hydrophobic interaction of tail-tail contributed to the reduced gel properties of the binary blend system. These findings provided new insight into the binary blend system of PM and AM with different ratios to change the gel properties of myofibrillar protein. • Paramyosin from field snail showed excellent thermal and pH stabilities. • The functional domain of PM was homologous to the myosin tail. • The gel property was enhanced when the binary blend gel with the low level of PM. • The self-aggregation of redundant PM increased the heterostructure of gel network. • The binary blend gel is a viable method to improve the gel quality of field snail. [ABSTRACT FROM AUTHOR]

Opercula of the gastropod Bithynia tentaculata are composed of calcite, and are typically 2–4 mm in length. They emit a thermoluminescence (TL) signal that can be used for dose reconstruction, and spatially resolved TL data from them can be obtained using an electron multiplying charge coupled device (EMCCD). However, when multiple measurements are made of the same sample with imaging detectors such as the EMCCD, registering the different images is crucial so that when regions of interest (ROI) are defined they consistently relate to the same part of the specimen. Previous work on opercula has undertaken this registration by hand, but this is prohibitively time consuming and is also potentially prone to human error. An automated registration process is described, and its use is illustrated using a dose recovery experiment. Without registration more than half of the regions of interest defined across the operculum failed the recycling test, and for those ROIs which did pass recycling the dose recovery ratio varied from 0.7 to 1.2. After registration more than 97% of ROIs passed recycling and all these ROIs gave dose recovery ratios within two sigma of unity. The automated registration process described here has potential for application to other types of solid sample such as rock slices provided they are not perfectly circular. • Imaging detectors providing new insights for dosimetry. • Registration of images essential for accurate spatially resolved analysis. • Automated image registration described for calcitic opercula. [ABSTRACT FROM AUTHOR]

[Display omitted] • Snail shell dust was employed as a potential biosorbent of heavy metal ions. • Shell dust adeptly removed Cd, Co, Cr and Cu from single and multi-metal solutions. • Metal ion removal mechanisms: chemisorption, ion exchange and surface precipitation. The generation of waste shells of edible freshwater snails, Filopaludina bengalensis and Pila globosa , following human consumption and use in aquaculture, encourages their utilisation as a potential biomaterial. In this experiment, we employed the shell dust derived from F. bengalensis (FSD) and P. globosa (PSD) shells as a biosorbent of Cd2+, Co2+, C r 2 O 7 2 - and Cu2+ from single- and multi-metal solutions. The results of batch adsorption experiments and characterisation of FSD and PSD using SEM, EDS, ICP-OES, FTIR, and XRD indicated that the metal ion removal process involved chemical adsorption (formation of CdCO 3 , Cu 2 CO 3 (OH) 2 and CoCO 3), ion exchange (reduced quantity of various elements on the shell dust following their release into the solution during adsorption) and surface precipitation. The best-fitted Langmuir isotherm specified monolayer adsorption with maximum adsorption capacity for Cd2+ (in single-metal system: FSD- 254.42, PSD- 327.76 mg/g; in multi-metal system: FSD: 93.79, PSD: 94.45 mg/g) and Cu2+ (in single-metal system: FSD- 234.63, PSD- 289.71 mg/g; in multi-metal system: FSD: 150.01, PSD: 160.51 mg/g). In multi-metal systems, the adsorption of Cd2+ and Cu2+ was antagonistic, and the adsorption of Co2+ and C r 2 O 7 2 - was synergistic in nature. The thermodynamic parameters suggest that the adsorption is endothermic, feasible and spontaneous. The successful removal of metal ions from single- and multi-metal solutions and real wastewater recommended FSD and PSD as eco-friendly and low-cost biosorbent for wastewater amelioration with implication in waste valorisation. [ABSTRACT FROM AUTHOR]

Snail control in aquaculture and control of snail vectors implicated in animal and human diseases are global challenges. Potential biocontrol agents could be species of crayfish, which are known to be voracious predators of snails. However, at present, the use of crayfish as biocontrol agents is limited due to their invasive nature. A promising candidate biocontrol agent is the Australian redclaw crayfish, Cherax quadricarinatus , a key species in the aquaculture industry. However, the downside of using this species for biocontrol is that C. quadricarinatus aquaculture escapees – being highly robust, fast growing, and ferocious omnivores – have become invasive, establishing feral populations around the world. Here we suggest the production of monosex C. quadricarinatus populations that open two exciting biotechnology applications—as a possible sustainable solution for snail control and as a means to improve yields and management in crayfish aquaculture, without the inherent danger of establishing invasive populations of aquaculture escapees. In the first part of this study, C. quadricarinatus was tested as a snail eradicator. Both males and females were highly efficient in predation experiments, eliminating 89% and 98% of Thiara scabra snails, respectively. The superior efficiency of the females in the predation experiments and the possible advantage for aquaculture of all-female crayfish populations provided the rationale for the second part of the study—the development of an economically feasible and non-labor-intensive biotechnology for the production of all-female C. quadricarinatus populations. To this end, we leveraged the naturally occurring intersexuality in C. quadricarinatus populations to produce female-biased populations. Females bearing only the W sex chromosome isolated from such populations using W and Z -specific genomic markers were found to be reproductive when bred with WZ intersexuals. Resulting progenies from the above crosses were 100% female populations including 50% WW females, thus paving the way to the establishment of an all-female producing brood stock. We present a quantitative scheme that demonstrates how our approach, which does not include any genomic intervention, can be implemented both for sustainable aquaculture and to fight harmful snails damaging aquaculture, agriculture, and human health. • Cherax quadricarinatus genomic sex markers were used for genotyping. • Cherax quadricarinatus were employed as disease-carrying snails eradicators. • For the first time, Non-GMO method to produce all-female C. quadricarinatus is used. • All-female crayfish for aquaculture and biocontrol reduces the risk of invasiveness. [ABSTRACT FROM AUTHOR]

A novel food followed by sickness, causes a taste-specific conditioned aversion, known as the 'Garcia effect'. We recently found that both a heat shock stressor (30 °C for 1 h - HS) and the bacterial lipopolysaccharide (LPS) can be used as 'sickness-inducing' stimuli to induce a Garcia effect in the pond snail Lymnaea stagnalis. Additionally, if snails are exposed to acetylsalicylic acid (ASA) present in aspirin tablets before the LPS injection, the formation of the Garcia effect is prevented. Here, we hypothesized that exposing snails to crushed aspirin before the HS (ASA-HS) would prevent the HS-induced 'sickness state' and – therefore –the Garcia effect. Unexpectantly, the ASA-HS procedure induced a generalized and long-lasting feeding suppression. We thus investigate the molecular effects underlying this phenomenon. While the exposure to the HS alone resulted in a significant upregulation of the mRNA levels of the Heat Shock Protein 70 (HSP 70) in snails' central ring ganglia, the ASA-HS procedure induced an even greater upregulation of HSP70, suggesting that the ASA-HS combination causes a severe stress response that inhibits feeding. Additionally, we found that the ASA-HS procedure induced a significant downregulation of the mRNA levels of genes involved with the serotoninergic system which regulates feeding in snails. Finally, the ASA-HS procedure prevented HS-induced upregulation of the mRNA levels of key neuroplasticity genes. Our study indicates that two sickness-inducing stimuli can have different physiological responses even if behavioral outcomes are similar under some learning contexts. [Display omitted] • Pairing a novel taste and a heat shock induces a taste-specific feeding suppression. • ASA exposure before the heat shock induces generalized feeding suppression. • ASA exposure before a heat shock upregulates the HSP70 mRNA levels. • ASA exposure before a heat shock downregulates TPH and SERT expression levels. • ASA exposure prevents the heat-induced upregulation of GRIN1 and CREB1 mRNA levels. [ABSTRACT FROM AUTHOR]

• As exhibits dose-dependent effects on P. canaliculata growth, with low levels promoting and high levels inhibiting. • Growth inhibition effects are attributed to cytological alterations in the shell and digestive gland. • Up-regulation of genes related to DNA replication and chitosan biosynthesis explains the growth promotion effects. • CYP450, glutathione, arachidonic acid, and ABC transporters involved in As metabolism and transport. Arsenic (As) pollution poses an important problem, but limited information is available about the physiological effects of As on freshwater invertebrates. Here , we investigated the physiological effects of chronic As exposure on Pomacea canaliculata , a freshwater invertebrate. High level of As (Ⅲ, 5 mg/L) inhibited the growth of P. canaliculata , whereas low level of As (Ⅲ, 2 mg/L) promoted growth. Pathological changes in shell and cellular ultrastructure due to As accumulation likely explain the growth inhibition at high As level. Low level of As simulated the expression of genes related to DNA replication and chitosan biosynthesis, potentially accounting for the growth promotion observed. High level of As enrichment pathways primarily involved cytochrome P450, glutathione, and arachidonic acid-mediated metabolism of xenobiotics. ATP-binding cassette (ABC) transporters, specifically the ABCB and ABCC subfamilies, were involved in As transport. Differential metabolites were mainly associated with the metabolism and biosynthesis of amino acids. These findings elucidate the dose-dependent effects of As stress on P. canaliculata growth, with low levels promoting and high levels inhibiting. Additionally, our findings also provide insights into As metabolism and transport in P. canaliculata. [ABSTRACT FROM AUTHOR]

Among the effects of the larval development of digenetic trematodes on their intermediate hosts, changes in the carbohydrate metabolism in the snails stand out. The aim of this study was to analyze, every 10 days after infection (d.p.i.), the effects of Paratanaisia bragai infection on the glycogen content in the digestive gland and cephalopedal mass in Subulina octona snail, and also verify the glucose concentration and the enzyme D - and L -lactate dehydrogenase activity (EC1.1.1.27 and EC1.1.1.28) (LDH) and the concentration of some metabolites(oxalic, succinic, pyruvic and lactic acid) presents in the hemolymph. Histochemical analisys were also performed. We verified a total increase of 54.81% in glucose concentration in infected snails and an oscillating pattern in the glycogen content in the cephalopedal mass and in the digestive gland. LDH activity shows an increase of 10 d.p.i. (+ 74.32%) and 40 d.p.i. (+ 47.81%) and decrease at 20 d.p.i. and 30 d.p.i. The concentrations of oxalic, succinic and pyruvic acids showed significant and progressive reductions; however, lactic acid had a significant increase. Histological and histochemical analysis showed a tissue disorganization in the cephalopedal mass of infected snails and morphological changes in the digestive gland. These results confirm that infection causes metabolic pathway changes in the snails due to activation of an alternative anaerobic pathway for producing energy, indicated by the increased lactic acid content and LDH activity. [ABSTRACT FROM AUTHOR]

Burns are a global public health problem and the treatment of burn wounds is a major medical and economic issue. White jade snails (Achatina fulica) are now widely distributed in Asia, and they have been used to treat burns in folk medicine of China. In this study, the glycoproteins from white jade snails were investigated and their effect on burn healing was evaluated by a mouse burn model. The results showed that the snail mucus was mainly composed of proteins and polysaccharides, and it had good adhesion. The main component of snail mucus was glycoprotein from the results of DEAE Sepharose FF ion exchange chromatography. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging effect of 1 mg/mL snail mucus reached 13.77%. The wound healing rate of the snail mucus group was higher than that of the control group (p < 0.0001). Histopathological results showed that mice in the snail mucus group had a faster healing than that of the control group. The biochemical analysis was in agreement with the histopathological findings. These results suggested that glycoproteins from snail mucus showed effective wound healing activities in the skin of experimentally burned mice. [ABSTRACT FROM AUTHOR]

• Species-specific emergence patterns of three Diplostomum spp. were studied. • Daily periodicity-dependent patterns in cercarial emergence were observed. • There was seasonal intraspecific variation in the daily cercarial output. • Patterns synchronised with reproduction and activity of fish second intermediate hosts. • Diplostomum spp. cercariae evolutionarily adapted to fish behaviour. The cercarial emergence patterns of three species of Diplostomum (Diplostomum ' mergi ', Diplostomum spathaceum and Diplostomum parviventosum) parasitizing freshwater first intermediate host Radix lagotis sampled in Most Lake, Czech Republic, were studied under various experimental conditions, i.e. field, laboratory and incubator, and seasons, i.e. spring, summer and autumn. We discovered unexpected daily periodicity-dependent species-specific emergence patterns among the three Diplostomum spp. depending on experimental conditions. At the same time, the intraspecific variation of D. spathaceum cercarial release in response to seasonal conditions was observed. We found that a complex array of mechanisms can affect Diplostomum species-specific patterns in cercarial emergence, of which behavioural characteristics of fish related to reproduction and feeding processes are considered the most important factors. This might represent a specific adaptive evolutionary mechanism to maximise transmission success while avoiding competition for host resources. Our results contribute to a better understanding of ecological and epidemiological aspects with respect to specific adaptive strategies compartmentalised among species of Diplostomum and consequences for infection risk in fish hosts. [ABSTRACT FROM AUTHOR]

The carbon and oxygen isotopic composition of land snail shells (δ13C shell and δ18O shell) has been used to reconstruct paleoenvironmental changes worldwide. Adding to the limited calibration information available for the monsoon marginal regions, we present δ13C and δ18O results for modern snails, plants and soils, collected from the Helan Mountains, in North China, spanning an altitudinal gradient of 1733–2851 m a.s.l. Linear regression analysis show that δ13C shell is positively correlated with altitude on both slopes, with similar rates of altitudinal variation; in contrast, δ18O shell is negatively correlated with altitude on the western slopes, but this effect is absent on the eastern slopes. The variations in the integrated δ13C signals of living vegetation and the flux of absorbed atmospheric CO 2 attributed to changes in metabolic rates are likely responsible for the altitudinal effect on δ13C shell above 2000 m a.s.l., while changes in vegetation type and/or carbonate ingestion by snails may be important in inducing the positive shift in δ13C shell below 2000 m a.s.l. δ18O shell is determined by the rainwater δ18O and by the fractionation processes between shell carbonate and snail body water, and both are controlled by the temperature of the alpine environment. In addition, evaporative enrichment of the body fluid or of the environmental water prior to ingestion by snails exerts an important influence on δ18O shell. Notably, both δ13C shell and δ18O shell in the study region respond more sensitively to climate than in the monsoon core area. The rate of change of δ13C shell in response to temperature and precipitation above the altitude of 2000 m a.s.l. are −0.87‰/°C and +2.76‰/100 mm, while the corresponding rates for δ18O shell on the western slopes are +0.41‰/°C and −1.29‰/100 mm. Our results expand the range of application of δ13C shell and δ18O shell as climatic indicators, and emphasize the differences in the climatic sensitivity of these proxies between the monsoon margin and core areas. In addition, the differences in shell isotope composition in response to environment changes between adjacent locations (i.e. on different slopes) in mountainous terrain need to be considered in future studies. [ABSTRACT FROM AUTHOR]

In seeking to understand the establishment of left–right (LR) asymmetry, a limiting factor is that most animals are ordinarily invariant in their asymmetry, except when manipulated or mutated. It is therefore surprising that the wider scientific field does not appear to fully appreciate the remarkable fact that normal development in molluscs, especially snails, can flip between two chiral types without pathology. Here, I describe recent progress in understanding the evolution, development, and genetics of chiral variation in snails, and place it in context with other animals. I argue that the natural variation of snails is a crucial resource towards understanding the invariance in other animal groups and, ultimately, will be key in revealing the common factors that define cellular and organismal LR asymmetry. Snails are the only animal group to ordinarily produce mirror-image forms. They have the potential to be an unequalled natural genetic resource in understanding chirality, including the invariant LR asymmetry of other animal groups. A formin gene is associated with variation in LR asymmetry in two snail species, although the mutation is pathological in both. The genes that produce chiral variation without pathology are still wholly unknown; changes in gene expression or of accessory factors are likely. Understanding LR asymmetry in snails will involve studies of early embryology and genomics, alongside whole-animal studies on the impact of natural and sexual selection. Chiral variation in snails may be enabled by the dichotomous nature of spiralian cleavage (dextral or sinistral), combined with the action of selection on the outward shell phenotype. [ABSTRACT FROM AUTHOR]

Snail mucus is an attractive natural substance, which is increasingly used in cosmetic creams and syrups thanks to its emollient, moisturizing, protective and reparative properties. The aim of the present study was to explore the physicochemical properties of chitosan-based films added with snail mucus extracted from Helix Aspersa Muller. To this aim, chitosan films at different content of snail mucus were fabricated by simple solvent casting technique. The results of X-ray diffraction analyses, tensile mechanical tests, Infrared spectroscopy and thermogravimetry demonstrated that snail mucus addition strongly modifies the properties of chitosan films. In particular, it acted like a plasticizer enhancing films extensibility up to ten times and strongly improving their water barrier and bioadhesion properties, with a trend depending on Snail mucus content. Furthermore, it provides the films with antibacterial properties and enhanced cytocompatibility, yielding materials with tailored properties for specific requirements. Unlabelled Image • Snail mucus addition confers functional properties to chitosan films. • Composite films can be stretched up more than ten times with respect to chitosan films. • Bioadhesion and water vapor barrier properties are highly enhanced. • Obtained films are natural materials with antibacterial activity. [ABSTRACT FROM AUTHOR]