Omega-3 polyunsaturated fatty acids in the brain and visual system: Focus on invertebrates.

A critical role of omega-3 polyunsaturated fatty acids (PUFA), mainly docosahexaenoic acid 22:6ω3 (DHA), in the development and function of the brain and visual system is well established. DHA, the most abundant omega-3 PUFA in the vertebrate brain, contributes to neuro- and synaptogenesis, neuronal differentiation, synaptic transmission and plasticity, neuronal network formation, memory and behaviour formation. Based on these data, the unique importance of DHA and its irreplaceability in neural and retinal tissues has been postulated. In this review, we consider omega-3 PUFA composition in the brain and retina of various invertebrates, and show that DHA has only been found in marine mollusks and crustaceans. A gradual decrease in the DHA content until its disappearance can be observed in the brain lipids of the series marine-freshwater-terrestrial crustaceans and marine-terrestrial mollusks, suggesting that the transition to the land lifestyle in the evolution of invertebrates, but not vertebrates, was accompanied by a loss of DHA. As with terrestrial crustaceans and mollusks, DHA was not found in insects, either terrestrial or aquatic, or in nematodes. We show that the nervous and visual systems of various DHA-free invertebrates can be highly enriched in alpha-linolenic acid 18:3ω3 or eicosapentaenoic acid 20:5ω3, which affect neurological and visual function, stimulating synaptogenesis, synaptic transmission, visual processing, learning and even cognition. The review data show that, in animals at different levels of organization, omega-3 PUFA are required for the functioning of the nervous and visual systems and that their specific needs can be met by various omega-3 PUFA.

Multidrug-Resistance of Vibrio Species in Bivalve Mollusks from Southern Thailand: Isolation, Identification, Pathogenicity, and Their Sensitivity toward Chitooligosaccharide-Epigallocatechin-3-Gallate Conjugate.

Vibrio spp. is a Gram-negative bacteria known for its ability to cause foodborne infection in association with eating raw or undercooked seafood. The majority of these foodborne illnesses are caused by mollusks, especially bivalves. Thus, the prevalence of Vibrio spp. in blood clams (Tegillarca granosa), baby clams (Paphia undulata), and Asian green mussels (Perna viridis) from South Thailand was determined. A total of 649 Vibrio spp. isolates were subjected to pathogenicity analysis on blood agar plates, among which 21 isolates from blood clams (15 isolates), baby clams (2 isolates), and green mussels (4 isolates) showed positive ß-hemolysis. Based on the biofilm formation index (BFI) of ß-hemolysis-positive Vibrio strains, nine isolates exhibited a strong biofilm formation capacity, with a BFI in the range of 1.37 to 10.13. Among the 21 isolates, 6 isolates (BL18, BL82, BL84, BL85, BL90, and BL92) were tlh-positive, while trh and tdh genes were not detected in all strains. Out of 21 strains, 5 strains showed multidrug resistance (MDR) against amoxicillin/clavulanic acid, ampicillin/sulbactam, cefotaxime, cefuroxime, meropenem, and trimethoprim/sulfamethoxazole. A phylogenetic analysis of MDR Vibrio was performed based on 16s rDNA sequences using the neighbor-joining method. The five MDR isolates were identified to be Vibrio neocaledonicus (one isolate), Vibrio fluvialis (one isolate) and, Vibrio cidicii (three isolates). In addition, the antimicrobial activity of chitooligosaccharide-epigallocatechin gallate (COS-EGCG) conjugate against MDR Vibrio strains was determined. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of COS-EGCG conjugate were in the range of 64-128 µg/mL. The antimicrobial activity of the conjugate was advocated by the cell lysis of MDR Vibrio strains, as elucidated by scanning electron microscopic images. Vibrio spp. isolated from blood clams, baby clams, and Asian green mussels were highly pathogenic, exhibiting the ability to produce biofilm and being resistant to antibiotics. However, the COS-EGCG conjugate could be used as a potential antimicrobial agent for controlling Vibrio in mollusks.

Responses of zebra and quagga mussels to copper and tribytiltin exposure: Bioconcentration, metabolic and cardiac biomarkers.

One of the top ecological priorities is to find sensitive indicators for pollution monitoring. This study focuses on the bioconcentration and responses (condition index, survival, oxygen consumption, heart rates, and oxidative stress and neurotoxic effect biomarkers) of mussels from the Volga River basin, Dreissena polymorpha and Dreissena bugensis, to long-term exposure to toxic chemicals such as tributyltin (TBT, 25 and 100 ng/L) and copper (Cu, 100 and 1000 µg/L). We found that TBT was present in the tissues of zebra and quagga mussels in comparable amounts, whereas the bioconcentration factor of Cu varied depending on its concentration in water. Differences in responses between the two species were revealed. When exposed to high Cu concentrations or a Cu-TBT mixture, quagga mussels had a lower survival rate and a longer heart rate recovery time than zebra mussels. TBT treatment caused neurotoxicity (decreased acetylcholinesterase activity) and oxidative stress (increased levels of thiobarbituric acid reactive substances) in both species. TBT and Cu levels in mussel tissues correlated positively with the condition index, but correlated with the level of acetylcholinesterase in the mussel gills. The principal component analysis revealed three main components: the first consists of linear combinations of 14 variables reflecting TBT water pollution, TBT and Cu levels in mussel tissues, and biochemical indicators; the second includes Cu water concentration, cardiac tolerance, and mussel size; and the third combines weight, metabolic rate, and heart rates. Quagga mussels are less tolerable to contaminants than zebra mussels, so they may be used as a sensitive indicator.

Hypoxia in the Blue Mussel Mytilus chilensis Induces a Transcriptome Shift Associated with Endoplasmic Reticulum Stress, Metabolism, and Immune Response.

The increase in hypoxia events, a result of climate change in coastal and fjord ecosystems, impacts the health and survival of mussels. These organisms deploy physiological and molecular responses as an adaptive mechanism to maintain cellular homeostasis under environmental stress. However, the specific effects of hypoxia on mussels of socioeconomic interest, such as Mytilus chilensis, are unknown. Using RNA-seq, we investigated the transcriptomic profiles of the gills, digestive gland, and adductor muscle of M. chilensis under hypoxia (10 days at 2 mg L-1) and reoxygenation (10 days at 6 mg L-1). There were 15,056 differentially expressed transcripts identified in gills, 11,864 in the digestive gland, and 9862 in the adductor muscle. The response varied among tissues, showing chromosomal changes in Chr1, Chr9, and Chr10 during hypoxia. Hypoxia regulated signaling genes in the Toll-like, mTOR, citrate cycle, and apoptosis pathways in gills, indicating metabolic and immunological alterations. These changes suggest that hypoxia induced a metabolic shift in mussels, reducing reliance on aerobic respiration and increasing reliance on anaerobic metabolism. Furthermore, hypoxia appeared to suppress the immune response, potentially increasing disease susceptibility, with negative implications for the mussel culture industry and natural bed populations. This study provides pivotal insights into metabolic and immunological adaptations to hypoxia in M. chilensis, offering candidate genes for adaptive traits.

Findings on three endocommensal scuticociliates (Protista, Ciliophora) from freshwater mollusks, including their morphology and molecular phylogeny with descriptions of two new species.

Species of the ciliate genera Myxophyllum and Conchophthirus are found as endocommensals of terrestrial and freshwater mollusks, respectively. So far, there have been few studies of these genera and morphological data for most members are often incomplete. In the present work, two new species, Myxophyllum weishanense sp. nov. and Conchophthirus paracurtus sp. nov., and a known species, Conchophthirus lamellidens, were isolated from hosts in Lake Weishan Wetland, China. Taxonomic studies indicate that M. weishanense sp. nov. can be recognized mainly by the combination of about 60 somatic kineties on both ventral and dorsal sides and the presence of caudal cilia. Conchophthirus paracurtus sp. nov. differs from congeners in its body shape and size, having a glabrous area on the posterior right side, and having fewer somatic kineties. In addition, differences in their ITS2 (Internally Transcribed Spacer 2) secondary structures support the discrimination of the two new species from their highly similar congeners. An improved diagnosis for the poorly known species, C. lamellidens is also provided. Phylogenetic analyses reveal that members of the genus Myxophyllum belong to a fully supported clade that is sister to a large, poorly supported clade consisting of Hemispeiridae, Ancistridae, and several lineages of the nonmonophyletic Cyclidiidae. The Myxophyllum clade also includes Protophyra ovicola JQ956552, a possible misidentification. Sequences of the two new Conchophthirus species cluster with other congeners in a fully supported clade that is unrelated to either the 'typical' thigmotrichs or to pleuronematids, thus conflicting with the traditional classification, and may represent an orphan scuticociliate lineage. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-024-00230-4.

Effects of different hydrological conditions on the taxonomic structure and functional traits of mollusk communities in a large floodplain wetland.

Floodplain wetlands are critical to the conservation of aquatic biodiversity and the ecological integrity of river networks. However, increasing drought severity and frequency caused by climate change can reduce floodplain wetlands' resistance and recovery capacities. Mollusks, which are common inhabitants of floodplain wetlands, are among the most vulnerable species to drought. However, the response of mollusk communities to drought has received little attention. Here, we investigated how the structure and functional traits of mollusk communities changed in response to varying hydrological conditions, including a flash drought (FD) in the Poyang Lake floodplain wetland. Our findings showed that FD strongly reduced mollusk abundance and biomass, decreased both α- and ß-diversity, and resulted in the extinction of bivalve taxa. A sudden shift in community trait structure was discovered due to the extinction of many species. These traits, which include deposit feeding, crawling, scraping, aerial respiration, and dormancy, help mollusks survive in FD and tolerate completely dry out of their Changhuchi habitat. Finally, we discovered that dissolved oxygen was an important controlling variable for mollusk communities during drought. Our findings provide a scientific basis for the management and conservation of floodplain wetland biodiversity in the context of increasing drought frequency and intensity.

Living under natural conditions of ocean acidification entails energy expenditure and oxidative stress in a mussel species.

We investigated the health conditions of the Mediterranean mussel Mytilus galloprovincialis recruited in the CO2 vents system of Castello Aragonese at Ischia Island (Mediterranean Sea). Individuals of M. galloprovincialis were sampled in three sites along the pH gradient (8.10, 7.7 and up to <7.4). Untargeted metabolomics and biochemical endpoints related to energetic metabolism, oxidative stress/damage, neurotoxicity and immune defense were analyzed. Corrosion of the valves occurred at low pH. A separation of the metabolome was observed along the pH gradient. Metabolites belonging to amino acids, nucleosides, lipids and organic osmolytes were significantly reduced in the organisms from the most acidified sites. The content of reactive oxygen species and the activity of glutathione peroxidase were reduced in organisms from the acidified sites compared to ambient pH, and no oxidative damage was induced. Overall results suggested the presence of an energy cost underpinning long-term survival in acidified conditions for this species.

DNA Methylation Machinery in Gastropod Mollusks.

The role of DNA methylation in mollusks is just beginning to be understood. This review synthesizes current knowledge on this potent molecular hallmark of epigenetic control in gastropods-the largest class of mollusks and ubiquitous inhabitants of diverse habitats. Their DNA methylation machinery shows a high degree of conservation in CG maintenance methylation mechanisms, driven mainly by DNMT1 homologues, and the presence of MBD2 and MBD2/3 proteins as DNA methylation readers. The mosaic-like DNA methylation landscape occurs mainly in a CG context and is primarily confined to gene bodies and housekeeping genes. DNA methylation emerges as a critical regulator of reproduction, development, and adaptation, with tissue-specific patterns being observed in gonadal structures. Its dynamics also serve as an important regulatory mechanism underlying learning and memory processes. DNA methylation can be affected by various environmental stimuli, including as pathogens and abiotic stresses, potentially impacting phenotypic variation and population diversity. Overall, the features of DNA methylation in gastropods are complex, being an essential part of their epigenome. However, comprehensive studies integrating developmental stages, tissues, and environmental conditions, functional annotation of methylated regions, and integrated genomic-epigenomic analyses are lacking. Addressing these knowledge gaps will advance our understanding of gastropod biology, ecology, and evolution.

Exposure to microplastics renders immunity of the thick-shell mussel more vulnerable to diarrhetic shellfish toxin-producing harmful algae.

Despite both microplastics (MPs) and harmful algae blooms (HABs) may pose a severe threat to the immunity of marine bivalves, the toxification mechanism underlying is far from being fully understood. In addition, owing to the prevalence and sudden occurrence characteristics of MPs and HABs, respectively, bivalves with MP-exposure experience may face acute challenge of harmful algae under realistic scenarios. However, little is known about the impacts and underlying mechanisms of MP-exposure experience on the susceptibility of immunity to HABs in bivalve mollusks. Taking polystyrene MPs and diarrhetic shellfish toxin-producing Prorocentrum lima as representatives, the impacts of MP-exposure on immunity vulnerability to HABs were investigated in the thick-shell mussel, Mytilus coruscus. Our results revealed evident immunotoxicity of MPs and P. lima to the mussel, as evidenced by significantly impaired total count, phagocytic activity, and cell viability of haemocytes, which may result from the induction of oxidative stress, aggravation of haemocyte apoptosis, and shortage in cellular energy supply. Moreover, marked disruptions of immunity, antioxidant system, apoptosis regulation, and metabolism upon MPs and P. lima exposure were illustrated by gene expression and comparative metabolomic analyses. Furthermore, the mussels that experienced MP-exposure were shown to be more vulnerable to P. lima, indicated by greater degree of deleterious effects on abovementioned parameters detected. In general, our findings emphasize the threat of MPs and HABs to bivalve species, which deserves close attention and more investigation.

Expanded expression of pro-neurogenic factor SoxB1 during larval development of gastropod Lymnaea stagnalis suggests preadaptation to prolonged neurogenesis in Mollusca.

Introduction: The remarkable diversity observed in the structure and development of the molluscan nervous system raises intriguing questions regarding the molecular mechanisms underlying neurogenesis in Mollusca. The expression of SoxB family transcription factors plays a pivotal role in neuronal development, thereby offering valuable insights into the strategies of neurogenesis. Methods: In this study, we conducted gene expression analysis focusing on SoxB-family transcription factors during early neurogenesis in the gastropod Lymnaea stagnalis. We employed a combination of hybridization chain reaction in situ hybridization (HCR-ISH), immunocytochemistry, confocal microscopy, and cell proliferation assays to investigate the spatial and temporal expression patterns of LsSoxB1 and LsSoxB2 from the gastrula stage to hatching, with particular attention to the formation of central ring ganglia. Results: Our investigation reveals that LsSoxB1 demonstrates expanded ectodermal expression from the gastrula to the hatching stage, whereas expression of LsSoxB2 in the ectoderm ceases by the veliger stage. LsSoxB1 is expressed in the ectoderm of the head, foot, and visceral complex, as well as in forming ganglia and sensory cells. Conversely, LsSoxB2 is mostly restricted to the subepithelial layer and forming ganglia cells during metamorphosis. Proliferation assays indicate a uniform distribution of dividing cells in the ectoderm across all developmental stages, suggesting the absence of distinct neurogenic zones with increased proliferation in gastropods. Discussion: Our findings reveal a spatially and temporally extended pattern of SoxB1 expression in a gastropod representative compared to other lophotrochozoan species. This prolonged and widespread expression of SoxB genes may be interpreted as a form of transcriptional neoteny, representing a preadaptation to prolonged neurogenesis. Consequently, it could contribute to the diversification of nervous systems in gastropods and lead to an increase in the complexity of the central nervous system in Mollusca.

Multiple invasions and predation: The impact of the crayfish Cherax quadricarinatus on invasive and native snails.

The pace of biological invasions has increased in recent decades, leading to multiple invasions and the potential dominance of invasive species, destabilizing local ecological networks. This provides opportunities to study new ecological species interactions, including predation. Tropical freshwaters have been particularly concerned by aquatic invasions and we focused here on the Martinique island (Lesser Antilles). We examined the predator-prey relationships involving invasive Thiarid snails (Tarebia granifera and Melanoides tuberculata) and the native Neritina punctulata, both confronted with a newcomer predator, the redclaw crayfish (Cherax quadricarinatus). We conducted several mesocosm experiments to assess the impact of crayfish predation on snail survival and the passive and active antipredator responses of snails. A first experiment indicated snail survival rates between 50% and 80%, depending on crayfish size and sex. Notably, there was a negative correlation between snail survival and male crayfish size and the predation method (shell crushing vs. "body sucking") varied with crayfish size. The second experiment suggested no refuge size for snails, with both very small (<5 mm) and very large (>5 mm) unable to escape predation, regardless of crayfish size (from 77 to 138 mm) or sex. Finally, we investigated the escape behavior of Thiarids regarding three crayfish cues. Melanoides tuberculata tend to bury in the substrate and T. granifera to climb up aquarium walls, what was expected from their shell morphologies, and both responding to crayfish cues within minutes. Overall, C. quadricarinatus proves to be an efficient snail predator with limited escape options for snails, potentially contributing to the decline of certain snail populations in Martinique. This omnivorous predator might impact other native species across different groups, including shrimps and fish. Our study underscores the urgent need for monitoring efforts, solidifying the redclaw crayfish reputation as a dangerous invasive species for freshwater macrobenthic faunas worldwide.

Phylogenomics of Neogastropoda: the backbone hidden in the bush.

The molluscan order Neogastropoda encompasses over 15,000 almost exclusively marine species playing important roles in benthic communities and in the economies of coastal countries. Neogastropoda underwent intensive cladogenesis in early stages of diversification, generating a 'bush' at the base of their evolutionary tree, that has been hard to resolve even with high throughput molecular data. In the present study to resolve the bush, we use a variety of phylogenetic inference methods and a comprehensive exon capture dataset of 1,817 loci (79.6% data occupancy) comprising 112 taxa of 48 out of 60 Neogastropoda families. Our results show consistent topologies and high support in all analyses at (super)family level, supporting monophyly of Muricoidea, Mitroidea, Conoidea, and, with some reservations, Olivoidea and Buccinoidea. Volutoidea and Turbinelloidea as currently circumscribed are clearly paraphyletic. Despite our analyses consistently resolving most backbone nodes, three prove problematic: First, uncertain placement of Cancellariidae, as the sister group to either a Ficoidea-Tonnoidea clade, or to the rest of Neogastropoda, leaves monophyly of Neogastropoda unresolved. Second, relationships are contradictory at the base of the major 'core Neogastropoda' grouping. Third, coalescence-based analyses reject monophyly of the Buccinoidea in relation to Vasidae. We analysed phylogenetic signal of targeted loci in relation to potential biases, and we propose most probable resolutions in the latter two recalcitrant nodes. The uncertain placement of Cancellariidae may be explained by orthology violations due to differential paralog loss shortly after the whole genome duplication, which should be resolved with a curated set of longer loci.

Characterization and Functional Analysis of Fads Reveals Δ5 Desaturation Activity during Long-Chain Polyunsaturated Fatty Acid Biosynthesis in Dwarf Surf Clam Mulinia lateralis.

Fatty acid desaturases (Fads), as key enzymes in the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFAs), catalyze the desaturation between defined carbons of fatty acyl chains and control the degree of unsaturation of fatty acids. In the present study, two Fads genes, designated MulFadsA and MulFadsB, were identified from the genome of the dwarf surf clam Mulinia lateralis (Mollusca, Mactridae), and their spatiotemporal expression was examined. MulFadsA and MulFadsB contained the corresponding conserved functional domains and clustered closely with their respective orthologs from other mollusks. Both genes were expressed in the developmental stages and all tested adult tissues of M. lateralis, with MulFadsA exhibiting significantly higher expression levels in adult tissues than MulFadsB. Subsequently, the effects of dietary microalgae on Fads expressions in the dwarf surf clam were investigated by feeding clams with two types of unialgal diets varying in fatty acid content, i.e., Chlorella pyrenoidosa (Cp) and Platymonas helgolandica (Ph). The results show that the expressions of MulFads were significantly upregulated among adult tissues in the Cp group compared with those in the Ph group. In addition, we observed the desaturation activity of MulFadsA via heterologous expression in yeasts, revealing Δ5 desaturation activity toward PUFA substrates. Taken together, these results provide a novel perspective on M. lateralis LC-PUFA biosynthesis, expanding our understanding of fatty acid synthesis in marine mollusks.

Heavy Metal Bioaccumulation in Peruvian Food and Medicinal Products.

To better query regional sources of metal(loid) exposure in an under-communicated region, available scientific literature from 50 national universities (undergraduate and graduate theses and dissertations), peer-reviewed journals, and reports published in Spanish and English were synthesized with a focus on metal(loid) bioaccumulation in Peruvian food and medicinal products utilized locally. The study considered 16 metal(loid)s that are known to exert toxic impacts on humans (Hg, Al, Sb, As, Ba, Be, Cd, Cr, Sn, Ni, Ag, Pb, Se, Tl, Ti, and U). A total of 1907 individual analyses contained within 231 scientific publications largely conducted by Peruvian universities were analyzed. These analyses encompassed 239 reported species classified into five main food/medicinal groups-plants, fish, macroinvertebrates and mollusks, mammals, and "others" category. Our benchmark for comparison was the World Health Organization (Codex Alimentarius) standards. The organisms most frequently investigated included plants such as asparagus, corn, cacao, and rice; fish varieties like trout, tuna, and catfish; macroinvertebrates and mollusks including crab and shrimp; mammals such as alpaca, cow, chicken eggs, and milk; and other categories represented by propolis, honey, lichen, and edible frog. Bioaccumulation-related research increased from 2 to more than 25 publications per year between 2006 and 2022. The results indicate that Peruvian food and natural medicinal products can have dangerous levels of metal(loid)s, which can cause health problems for consumers. Many common and uncommon food/medicinal products and harmful metals identified in this analysis are not regulated on the WHO's advisory lists, suggesting the urgent need for stronger regulations to ensure public safety. In general, Cd and Pb are the metals that violated WHO standards the most, although commonly non-WHO regulated metals such as Hg, Al, As, Cr, and Ni are also a concern. Metal concentrations found in Peru are on many occasions much higher than what has been reported elsewhere. We conclude that determining the safety of food/medicinal products is challenging due to varying metal concentrations that are influenced not only by metal type but also geographical location. Given the scarcity of research findings in many regions of Peru, urgent attention is required to address this critical knowledge gap and implement effective regulatory measures to protect public health.

Leveraging Plasma-Activated Seawater for the Control of Human Norovirus and Bacterial Pathogens in Shellfish Depuration.

Cold plasma is a promising alternative for water treatment owing to pathogen control and a plethora of issues in the agriculture and food sectors. Shellfish pose a serious risk to public health and are linked to large viral and bacterial outbreaks. Hence, current European regulations mandate a depuration step for shellfish on the basis of their geographical growth area. This study investigated the inactivation of relevant viral and bacterial pathogens of three plasma-activated seawaters (PASWs), and their reactive oxygen and nitrogen species (RONS) composition, as being primarily responsible for microbial inactivation. Specifically, F-specific (MS2) and somatic (φ174) bacteriophage, cultivable surrogate (murine norovirus, MNV, and Tulane virus, TV), and human norovirus (HuNoV GII.4) inactivation was determined using plaque counts and infectivity assays, including the novel human intestinal enteroid (HIE) model for HuNoV. Moreover, the kinetic decay of Escherichia coli, Salmonella spp., and Vibrio parahaemolyticus was characterized. The results showed the complete inactivation of phages (6-8 log), surrogates (5-6 log), HuNoV (6 log), and bacterial (6-7 log) pathogens within 24 h while preventing cytotoxicity effects and preserving mussel viability. Nitrites (NO2-) were found to be mostly correlated with microbial decay. This research shows that PASWs are a suitable option to depurate bivalve mollusks and control the biohazard risk linked to their microbiological contamination, either viral or bacterial.

Snail extract for skin: A review of uses, projections, and limitations.

BACKGROUND: Snail mucin is becoming increasingly popular for its wide range of ingredients and potential benefits. Snail extract's widespread appearance in cosmetic formulations encourages an investigation into the medical and cosmetic benefits. AIMS: This study aims to explore current literature on the variety of snail mucin applications. Specifically, we present a review of the uses, global market estimates and projects, and limitations to snail mucin. METHODS: A literature search was conducted on PubMed reviewing snail mucin and their application in medical and dermatologic fields examining their uses. Economic reports were also investigated for Global Market estimates. RESULTS: The therapeutic use of snail mucin in medical fields has been studied as antimicrobial agents, drug delivery vehicles, antitumor agents, wound healing agents, and biomaterial coatings among others. Additionally, the use in cosmetic fields includes antiaging, hydrating, anti-acne, scarring, and hyperpigmentation treatments. It is important to highlight that most studies conducted were preclinical or small clinical studies, stressing the need for additional large-scale clinical trials to support these claims. Investigations into the global market found estimates ranging from $457 million to $1.2 billion with upward projections in the upcoming decade. Limitations include ethical habitats for collection, allergy investigation, and missing clinical studies. CONCLUSIONS: The findings presented here emphasize the expanding uses of snail mucin and its ingredients alongside a growing market cosmetic industry should consider. We also emphasize the need for appropriate clinical trials into the stated benefits of snail mucin to ensure consumer safety and ethical extraction of mucin.

Aluminum exposure alters the pedal mucous secretions of the chocolate-band snail, Eobania vermiculata (Gastropoda: Helicidae).

Aluminum (Al) is used in everyday life and present in food drugs, packaging, industry, and agriculture. Although it is the most common metal in the Earth crust, a correlation has been demonstrated between its presence and various pathologies, even serious ones, especially of a neurological type. However, there is a histological gap regarding the role Al can have in contact with the covering and secreting epithelia. The alterations of the ventral and dorsal foot mucocytes and their secretions of the snail Eobania vermiculata caused by Al were investigated in situ by histochemical and lectin-histochemical techniques. Administration to different experimental groups took place for 3 and 9 days with 50 and 200 µM of AlCl3. Several types of mucocytes were detected with a prevalent secretion of acid glycans in the foot of E. vermiculata. Sulfated glycans prevail in the dorsal region, with one type showing only fucosylated residues and another also having galactosaminylated and glycosaminylated residues. Carboxylated glycans prevail in the ventral region, with presence of galactosaminylated, glycosaminylated, and fucosylated residuals in both cells. Snails treated presented a general decrease of mucin amount in the secreting cells and affected the mucus composition. These changes could alter the rheological and functional properties of the mucus with possible implications for the health of the treated animals. RESEARCH HIGHLIGHTS: Snails were fed with Al-contaminated lettuce at different concentrations. In the foot mucocytes produced mucus with prevailing acidic glycans. In the treated resulted a reduction in the amount of mucus and an alteration of glycan composition.

First characterization of the nuclear receptor superfamily in the Mediterranean mussel Mytilus galloprovincialis: developmental expression dynamics and potential susceptibility to environmental chemicals.

Endocrine-disrupting chemicals (EDCs) represent a global threat to human health and the environment. In vertebrates, lipophilic EDCs primarily act by mimicking endogenous hormones, thus interfering with the transcriptional activity of nuclear receptors (NRs). The demonstration of the direct translation of these mechanisms into perturbation of NR-mediated physiological functions in invertebrates, however, has rarely proven successful, as the modes of action of EDCs in vertebrates and invertebrates seem to be distinct. In the present work, we investigated the members of the NR superfamily in a bivalve mollusk, the Mediterranean mussel Mytilus galloprovincialis. In addition to annotating the M. galloprovincialis NR complement, we assessed the potential developmental functions and susceptibility to EDC challenge during early development by gene expression analyses. Our results indicate that a majority of mussel NRs are dynamically expressed during early development, including receptors characterized by a potential susceptibility to EDCs. This study thus indicates that NRs are major regulators of early mussel development and that NR-mediated endocrine disruption in the mussel could be occurring at a larger scale and at earlier stages of the life cycle than previously anticipated. Altogether, these findings will have significant repercussions for our understanding of the stability of natural mussel populations. This article is part of the theme issue 'Endocrine responses to environmental variation: conceptual approaches and recent developments'.

Copper and zinc isotope systematics in different bivalve mollusk species from the French coastline: Implications for biomonitoring.

Zinc (Zn) and copper (Cu) stable isotopic compositions have been analyzed in various species of bivalve mollusks worldwide, but no comprehensive systematic interspecies comparison exists. Thus, we assessed isotope differences between species harvested in emblematic French coastal ecosystems to unveil biologically driven Cu and Zn isotope fractionation patterns. Inter-species isotopic variability of Cu is larger than Zn, with organisms that regulate internal concentrations displaying preferential bioaccumulation of heavy isotopes. The degree of internal isotope fractionation decreases from mussels > clams > oysters, affecting Cu more than Zn. The less pronounced Zn inter-specie variability helps preserve source information more reliably. Spatial analysis of a single oyster species denotes thus an important isotope variability of environmental Zn sources, including natural, anthropogenic and dietary components. Overall, results highlight the importance of considering systematic offset in Cu and Zn isotope values when comparing data from different bivalve species.