Studies on the Adhesive Property of Snail Adhesive Mucus

Extraction, structure, pharmacological activities and applications of polysaccharides and proteins isolated from snail mucus

Snail mucus had medical applications for wound healing as early as ancient Greece and the late Han Dynasty (China). A literature search found 165 modern research papers discussing the extraction methods, chemical compositions, pharmacological activities, and applications of snail mucus. Thus, this review summarized the research progress on the extraction, structure, pharmacological activities, and applications of polysaccharides and proteins isolated from snail mucus. The extraction methods of snail mucus include natural secretion and stimulation with blunt force, spray, electricity, un-shelling, ultrasonic-assisted, and ozone-assisted. As a natural product, snail mucus mainly comprises two polysaccharides (glycosaminoglycan, dextran), seven glycoproteins (mucin, lectin), various antibacterial peptides, allantoin, glycolic acid, etc. It has pharmacological activities that encourage cell migration and proliferation, and promote angiogenesis and have antibacterial, anti-oxidative and anticancer properties. The mechanism of snail mucus' chemicals performing antibacterial and wound-healing was proposed. Snail mucus is a promising bioactive product with multiple medical applications and has great potential in the pharmaceutical and healthcare industries. Therefore, this review provides a valuable reference for researching and developing snail mucus.

Performance and characterization of snail adhesive mucus as a bioflocculant against toxic Microcystis

Toxic Microcystis blooms are widespread in aquatic bodies, posing major threats to aquatic and human life. Recently, bioflocculants have attracted considerable attention as a promising biomaterial for Microcystis management. In search of a novel organism that can produce an efficient bioflocculant for controlling harmful algae sustainably, the native gastropod Cipangopaludina chinensis was co-cultured continuously with toxic Microcystis under different initial algal cell densities. The bioflocculation effect of snail mucus on toxic Microcystis, microcystin removal, and toxin accumulation in snails was investigated. In addition, the properties of the adhesive mucus were characterized using microscopic, X-ray diffraction, infrared spectroscopy, and polysaccharide and proteome analyses. Microcystis cells were captured and flocculated by the snail mucus; removal efficiencies of up to 89.9% and 84.8% were achieved for microalgae and microcystin-leucine arginine (MC-LR), respectively, when co-cultured with C. chinensis for only one day. After nine-day exposure, less than 5.49 µg/kg DW microcystins accumulated in the snails, indicating safety for human consumption. The snail mucus contained 104.3 µg/mg protein and 72.7 µg/mg carbohydrate, which provide several functional groups beneficial for Microcystis bioflocculation. The main monosaccharide subunits of polysaccharides are galactose, galactosamine, glucosamine, fucose, glucose, and mannose. Most of them are key components of polysaccharides in many bioflocculants. Gene Ontology analysis indicated the protein enrichment in binding processes and catalytic activity, which may account for Microcystis bioflocculation via protein binding or enzymatic reactions. The findings indicate that native C. chinensis secretes adhesive mucus that can act as bioflocculant for toxic Microcystis from ambient water and can be an effective and eco-friendly tool for Microcystis suppression.

Coacervate or precipitate? Formation of non-equilibrium microstructures in coacervate emulsions

Non-equilibrium processing of aqueous polyelectrolyte complex (PEC) coacervates is critical to many applications. In particular, many coacervate-forming systems are known to become trapped in out-of-equilibrium states (e.g., precipitation). The mechanism and conditions under which these states form, and whether they age, is not clearly understood. Here, we elucidate the influence of processing on the PEC coarsening mechanism as it varies with flow during mixing for a model system of poly(allylamine hydrochloride) and poly(acrylic acid sodium salt) in water. We demonstrate that flow conditions can be used to toggle the formation of rough, precipitate-like aggregates of micron-scale PEC structures. These structures form at compositions with viscous-dominant equilibrium rheology, and observations of their formation via optical microscopy suggest that they comprise colloidal aggregates of PEC coacervate droplets. We further show that these aggregates exhibit micron-scale coarsening, with a mixing time-dependent characteristic aging time scale. The results show that the formation of precipitate-like structures is not solely determined by composition, but is instead highly sensitive to mass transport and colloidal instability effects. Our observations suggest that the details of mixing flow can provide non-equilibrium structural control of a broad range of PEC coacervate materials orthogonally to structure-property inspired polymeric design. We anticipate that these findings will open the door for future studies on the control of non-equilibrium PEC formation and structure.

Particle binding capacity of snail saliva

Gastropods forage with their radula, a thin chitinous membrane with embedded teeth, which scratch across the substrate to lose food particles. During this interaction, the risk of loosening particles is obvious without having a specialized mechanism holding them on the tooth surface. As mucus secretions are essential in molluscan life cycles and the locomotion and attachment gels are known to have an instant high adhesion, we have hypothesized that the saliva could support particle retention during feeding. As adhesion of snail saliva was not studied before, we present here an experimental setup to test its particle-binding capacity using a large land snail (Lissachatina fulica, Stylommatophora, Heterobranchia). This experiment was also applied to the gels produced by the snail foot for comparison and can be potentially applied to various fluids present at a small volume in the future. We found, that the saliva has high particle retention capacity that is comparable to the foot glue of the snail. To gain some insight into the properties of the saliva, we additionally studied it in the scanning electron microscope, estimated its viscosity in a de-wetting experiment, and investigated its elemental composition using energy dispersive X-ray spectroscopy reveling higher contents of Ca, Zn and other potential cross-linkers similar to those found in the glue.

Gastropod Mucus: Interdisciplinary Perspectives on Biological Activities, Applications, and Strategic Priorities

Terrestrial gastropod mucus exhibits multifunctional attributes, enabling diverse applications. This comprehensive review integrates insights across biomedicine, biotechnology, and intellectual property to elucidate the bioactivities, physicochemical properties, and ecological roles of snail and slug mucus. Following an overview of mucus functional roles in gastropods, promising applications are highlighted in wound healing, antimicrobials, biomaterials, and cosmetics, alongside key challenges. An analysis of global patent trends reveals surging innovation efforts to leverage gastropod mucus. Strategic priorities include bioprospecting natural diversity, optimizing stabilization systems, recombinant biosynthesis, and fostering collaboration to translate promising potentials sustainably into impactful technologies. Ultimately, harnessing the remarkable multifunctionality of gastropod mucus holds immense opportunities for transformative innovations in biomedicine, biotechnology, and beyond.

Comparative mucomic analysis of three functionally distinct Cornu aspersum Secretions

Every animal secretes mucus, placing them among the most diverse biological materials. Mucus hydrogels are complex mixtures of water, ions, carbohydrates, and proteins. Uncertainty surrounding their composition and how interactions between components contribute to mucus function complicates efforts to exploit their properties. There is substantial interest in commercializing mucus from the garden snail, Cornu aspersum, for skincare, drug delivery, tissue engineering, and composite materials. C. aspersum secretes three mucus-one shielding the animal from environmental threats, one adhesive mucus from the pedal surface of the foot, and another pedal mucus that is lubricating. It remains a mystery how compositional differences account for their substantially different properties. Here, we characterize mucus proteins, glycosylation, ion content, and mechanical properties that could be used to provide insight into structure-function relationships through an integrative "mucomics" approach. We identify macromolecular components of these hydrogels, including a previously unreported protein class termed Conserved Anterior Mollusk Proteins (CAMPs). Revealing differences between C. aspersum mucus shows how considering structure at all levels can inform the design of mucus-inspired materials.

Multi-Bioinspired Functional Conductive Hydrogel Patches for Wound Healing Management

Many hydrogel patches are developed to solve the pervasive and severe challenge of complex wound healing, while most of them still lack satisfactory controllability and comprehensive functionality. Herein, inspired by multiple creatures, including octopuses and snails, a novel muti-functional hydrogel patch is presented with controlled adhesion, antibacterial, drug release features, and multiple monitoring functions for intelligent wound healing management. The patch with micro suction-cup actuator array and a tensile backing layer is composed of tannin grafted gelatin, Ag-tannin nanoparticles, polyacrylamide (PAAm) and poly(N-isopropylacrylamide) (PNIPAm). In virtue of the photothermal gel-sol transition of tannin grafted gelatin and Ag-tannin nanoparticles, the patches exert a dual anti-microbial effect and temperature-sensitive snail mucus-like features. In addition, as the "suction-cups" consisting of thermal responsive PNIPAm can undergo a contract-relax transformation, the medical patches can adhere to the objects reversibly and responsively, and release their loaded vascular endothelial growth factor (VEGF) controllably for wound healing. More attractively, benefiting from their fatigue resistance, self-healing ability of the tensile double network hydrogel, and electrical conductivity of Ag-tannin nanoparticles, the proposed patches can report multiple wound physiology parameters sensitively and continuously. Thus, it is believed that this multi-bioinspired patch has immense potential for future wound healing management.

Nutritional Composition, Fatty Acids Profile, Mineral Content, Antioxidant Activity and Acute Toxicity of the Flesh of Helix aspesra Müller

Humans consume snail flesh as part of their diet. To assess its nutritional value and toxicity, chemical analyses were conducted to confirm the presence of protein, total and reduced carbohydrates, fat, fatty acid composition and mineral components. Furthermore, an acute toxicity study was carried out to determine the safety of Helix aspersa Müller snail flesh. H. aspersa Müller snail flesh exhibits a high nutritional content, a good ω3/ω6 ratio and higher levels of unsaturated fatty acids. Various minerals have been found in the flesh of H. aspersa Müller. Around 76.91 kcal, or 3.84% of the energy of a daily meal of 2000 kcal, are present in 100 g of this flesh. The evaluation of the antioxidant capacity indicated that the flesh's extracts contained a large quantity of antioxidant biomolecules. Administration of the aqueous extract of H. aspersa Müller flesh didn't cause death in laboratory rats, indicating that the lethal dose 50 is greater than 2000 mg·kg-1 body weight. The consumption of the flesh of H. aspersa Müller is highly recommended for human consumption due to its high concentration of nutrients and essential elements, as well as unsaturated fats, and due to its safety.

Standardized Extract from Wastes of Edible Flowers and Snail Mucus Ameliorate Ultraviolet B-Induced Damage in Keratinocytes

Several studies have highlighted the ability of snail mucus in maintaining healthy skin conditions due to its emollient, regenerative, and protective properties. In particular, mucus derived from Helix aspersa muller has already been reported to have beneficial properties such as antimicrobial activity and wound repair capacity. In order to enhance the beneficial effects of snail mucus, a formulation enriched with antioxidant compounds derived from edible flower waste (Acmella oleracea L., Centaurea cyanus L., Tagetes erecta L., Calendula officinalis L., and Moringa oleifera Lam.) was obtained. UVB damage was used as a model to investigate in vitro the cytoprotective effects of snail mucus and edible flower extract. Results demonstrated that polyphenols from the flower waste extract boosted the antioxidant activity of snail mucus, providing cytoprotective effects in keratinocytes exposed to UVB radiation. Additionally, glutathione content, reactive oxygen species (ROS), and lipid peroxidation levels were reduced following the combined treatment with snail mucus and edible flower waste extract. We demonstrated that flower waste can be considered a valid candidate for cosmeceutical applications due to its potent antioxidant activity. Thus, a new formulation of snail mucus enriched in extracts of edible flower waste could be useful to design innovative and sustainable broadband natural UV-screen cosmeceutical products.

Abalone adhesion: The role of various adhesion forces and their proportion to total adhesion force

Adhesion is the basic ability of many kinds of animals in nature, which ensures the survival and reproduction of animal populations. The aquatic abalone has a strong adhesion capacity. In this study, we observed the microscopic morphology of abalone abdominal foot surface, and found that the surface was covered with a large number of fibers. Then five types of force measuring plates were designed and processed for the adhesion test of abalone abdominal foot. According to the test results, the composition of abalone abdominal foot adhesion force was analyzed and the proportion of various adhesion force to the total adhesion force of abalone abdominal foot was calculated. Among them, the vacuum adhesion force accounts for more than half of the total adhesion force of abalone abdominal foot, and its proportion is more than 60%. Van der Waals force also plays an important role, and its proportion is more than 20%. The proportion of capillary force is very small, which is only about 1%. Its main role is to form a liquid film to prevent the gas from flowing into the sucker. The vacuum adhesion of abalone abdominal foot can be further divided into the whole adhesion of abdominal foot, the local adhesion of abdominal foot and the frictional equivalent vacuum adhesion. And the whole adhesion of abdominal foot is basically equivalent to the local adhesion of abdominal foot. This study quantifies the proportion of various adhesion forces to the total adhesion force of the abdominal foot, which provides a reference for the further study of other adhesive creatures and the design of bionic underwater adhesion devices.

Adhesive Interfaces toward a Zero-Waste Industry

This Feature Article evaluates ongoing efforts to adapt adhesives toward the goal of zero-waste living and suggests the most promising future directions. Adhesives are not always considered in zero-waste manufacturing because they represent only a small fraction of a product and offer no additional functionality. However, their presence restricts the reintegration of constituent parts into a circular economy, so a new generation of adhesives is required. Furthermore, their production often leads to harmful pollutants. Here, two main approaches toward addressing these problems are considered: first, the use of natural materials that replace petroleum-based polymers from which conventional adhesives are made and second, the production of dismantlable adhesives capable of debonding on demand with the application of an external stimulus. These approaches, either individually or combined, offer a new paradigm in zero-waste industrial production and consumer applications.

Mucus-derived exosome-like vesicles from the Spanish slug (Arion vulgaris): taking advantage of invasive pest species in biotechnology

The slug Arion vulgaris has attracted major attention as one of the worst invasive herbivore pests in Europe and is renowned for the stiff mucus it secretes for locomotion. In this study we focused on the isolation and characterisation of extracellular vesicles, specifically exosomes and exosome-like vesicles, from Arion secretions. We developed a method for slug mucus collection and subsequent vesicle isolation by ultracentrifugation. The isolated vesicles with an average diameter of ~ 100 nm carry abundant proteins and short RNAs, as well as adhesion molecules similar to mammalian galectins. We demonstrated that the slug extracellular vesicles are internalised by plant cells and human cancer cells in in vitro assays and are loadable by bioactive compounds, which makes them an interesting tool for utilisation in biotechnology.

High Performance Marine and Terrestrial Bioadhesives and the Biomedical Applications They Have Inspired

This study has reviewed the naturally occurring bioadhesives produced in marine and freshwater aqueous environments and in the mucinous exudates of some terrestrial animals which have remarkable properties providing adhesion under difficult environmental conditions. These bioadhesives have inspired the development of medical bioadhesives with impressive properties that provide an effective alternative to suturing surgical wounds improving closure and healing of wounds in technically demanding tissues such as the heart, lung and soft tissues like the brain and intestinal mucosa. The Gecko has developed a dry-adhesive system of exceptional performance and has inspired the development of new generation re-usable tapes applicable to many medical procedures. The silk of spider webs has been equally inspiring to structural engineers and materials scientists and has revealed innovative properties which have led to new generation technologies in photonics, phononics and micro-electronics in the development of wearable biosensors. Man made products designed to emulate the performance of these natural bioadhesive molecules are improving wound closure and healing of problematic lesions such as diabetic foot ulcers which are notoriously painful and have also found application in many other areas in biomedicine. Armed with information on the mechanistic properties of these impressive biomolecules major advances are expected in biomedicine, micro-electronics, photonics, materials science, artificial intelligence and robotics technology.

Effectiveness of Snail Slime in the Green Synthesis of Silver Nanoparticles

The development of green, low cost and sustainable synthetic routes to produce metal nanoparticles is of outmost importance, as these materials fulfill large scale applications in a number of different areas. Herein, snail slime extracted from Helix Aspersa snails was successfully employed both as bio-reducing agent of silver nitrate and as bio-stabilizer of the obtained nanoparticles. Several trials were carried out by varying temperature, the volume of snail slime and the silver nitrate concentration to find the best biogenic pathway to produce silver nanoparticles. The best results were obtained when the synthesis was performed at room temperature and neutral pH. UV-Visible Spectroscopy, SEM-TEM and FTIR were used for a detailed characterization of the nanoparticles. The obtained nanoparticles are spherical, with mean diameters measured from TEM images ranging from 15 to 30 nm and stable over time. The role of proteins and glycoproteins in the biogenic production of silver nanoparticles was elucidated. Infrared spectra clearly showed the presence of proteins all around the silver core. The macromolecular shell is also responsible of the effectiveness of the synthesized AgNPs to inhibit Gram positive and Gram negative bacterial growth.

Antimicrobial efficacy of Egyptian Eremina desertorum and Helix aspersa snail mucus with a novel approach to their anti-inflammatory and wound healing potencies

Snail mucus is composed of bioactive compounds thought to have different biological properties for the treatment of some skin problems. Although Helix aspersa mucus is used in several cosmetic products, a detailed characterization of Eremina desertorum mucus composition and its biological activities is still missing. Mucus extracts (MEs) from H. aspersa and E. desertorum were prepared and tested for their antimicrobial and anti-inflammatory activities with their potencies in wound healing. Also, chemical characterization was performed by GC-MS analysis. Results showed that ME of E. desertorum gave higher inhibitory activity against resistant strains related to burn wound infections compared to ME of H. aspersa. Additionally, it revealed a significant anti-inflammatory activity. Moreover, we found that ME of E. desertorum lacked cytotoxicity and was able to significantly induce cell proliferation and migration through up-regulation of TGF-β1 and VEGF gene expression. Our results suggested that MEs of E. desertorum have higher biological effects than H. aspersa, which are attributable to antimicrobial, anti-inflammatory activities, cell proliferation and pave the way for further investigating its potential effect as a human therapeutic agent.

Response mechanisms of snails to the pulling force and its potential application in vacuum suction

Snails offer successful attachment and locomotion on horizontal and vertical surfaces, and have inspired extensive research to develop artificial adhesives. Here, we experimentally investigate the response mechanisms of snails to mechanical signals (pull-off force and crawling angle), then propose a way to design a bioinspired sucker, and theoretically analysis its application in vacuum suction. The experimental results indicate that the pull-off force is 7 N, about 22 times of its weight, and relatively invariant across the angles of the substrate. The flexible body increases work consumption by stretching and deformation during pulling, and a cavity with negative pressure differential can exist at the interface to help resist the pulling. We extract the flexible body and formation of a negative pressure cavity at the contact interface as two key elements of the bioinspired sucker, and the analysis shows that it can be adaptable to an extend range of products compared with conventional vacuum suction, which illustrates the potential for industrial or robotic manipulation.

Effect of Metals on Underwater Adhesion of Gastropod Adhesive Mucus

Many gastropods release mucus hydrogels, which help them to remain attached to different substrates. Although not as strong as synthetic or biomimetic adhesives, some of these hydrogels have the ability to adhere to wet surfaces. These complex hydrogels mainly consist of proteins and carbohydrates, their natural cross-linking reactions being dependent on the presence of metals. In this paper, we investigated the role of metals in improving the underwater adhesive property of the mucus hydrogel from the slug Laevicaulis alte. We found that the strength and duration of attachment of two glass surfaces under water by the mucus hydrogel could be enhanced by its simple treatment with salts of metals, namely, Ca, Mg, Cu, or Zn. The degree of enhancement followed the order Ca²⁺ < Mg²⁺ < Zn²⁺ < Cu²⁺. The Cu²⁺-treated hydrogel kept two glass surfaces attached under water for about 20 days, while Zn²⁺ treatment caused attachment for about 15 days, as compared to the 3-5 days of attachment caused by the untreated gel. Treatment with both metals increased the underwater stability of the hydrogel almost threefold, presumably by strengthening its cross-linking. However, the Cu²⁺-treated hydrogel fell short of its adhesive function in the case of fast attachment within time scale of minutes, showing considerably low adhesive strength. From this study, we conclude that the treatment with Zn²⁺ is the best choice for improvement of the underwater adhesive property in terms of strength and stability. Overall, this work presents a novel biological underwater adhesive. The dynamic behavior of this multicomponent hydrogel in a versatile metal-rich environment may guide us toward designing new useful biomimetics.

Novel drug-loaded film forming patch based on gelatin and snail slime

Gelatin-based films enriched with snail slime are proposed as novel biodegradable and naturally bioadhesive patches for cutaneous drug delivery. Films (thickness range 163-248 μm) were stretchable and they adhered firmly onto the wetted skin, especially those with high amount (70% V/V) of snail slime extract. Fluconazole was selected as model drug and added to films containing the highest amount of snail slime. The presence of Fluconazole (4.53 ± 0.07% w/w) did not modify significantly the mechanical properties, the swelling degree and the bioadhesive performances of the films. Structural investigations demonstrated that the crystalline form III of the drug changed to the amorphous one, forming an amorphous solid dispersion. Moreover, snail slime prevented the drug recrystallization over time. In vitro permeation studies showed that film exhibited a cumulative drug concentration (over 60% in 24 h) similar to that of the control solution containing 20% w/V of ethanol. Fluconazole-loaded gelatin films proved to be effective towards clinical isolates of Candida spp. indicating that the drug maintained its remarkable antifungal activity once formulated into gelatin and snail slime-based films. In conclusion, snail slime, thanks to its peculiar composition, has proved to be responsible of optimal skin adhesion, film flexibility and of the formation of a supersaturating drug delivery system able to increase skin permeation.

Wound-healing activity of glycoproteins from white jade snail (Achatina fulica) on experimentally burned mice

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.

Physiological and behavioral responses of land molluscs as biomarkers for pollution impact assessment: A review

Environmental pollution caused by human activities is a global public health concern. This review discusses the impact of different types of pollutants such as pesticides, metals, nanoparticles and others on land molluscs. These molluscs are of great interest as good model organisms for studying biomarker responses in ecotoxicological monitoring programs. Several biomarkers are utilized to characterize and quantify the exposure and harmful impacts of various pollutants. In this review, we have identified physiological and behavioral endpoints (feeding, growth, avoidance, mucus secretion, locomotion and reproductive behavior) for the diagnosis of environmental pollution. The present review displays that all types of pollutants can disturb physiological and behavioral endpoints of gastropods, and these impacts depend on the matrix, exposure time and route as well as the type and concentration of the pollutants in the environment. We have also confirmed that terrestrial gastropods particularly snails as sentinel species could be used as potential bioindicator organisms for environmental quality assessment and thus for predicting potential hazards to human health.

Design and Synthesis of Mucin-Inspired Glycopolymers

Mucins are bottlebrush biopolymers that are glycoproteins on the surfaces of cells and as hydrogels secreted inside and outside the body. Mucin function in biology includes cell-cell recognition, signaling, protection, adhesion, and lubrication. Because of their attractive and diverse properties, mucins have recently become the focus of synthetic efforts by researchers who hope to understand and emulate these biomaterials. This review is focused on the development of methodologies for preparing mucin-inspired synthetic oligomers and glycopolymers, including solid-phase synthesis, polymerization of glycosylated monomers, and post-polymerization grafting of glycans to polymer chains. How these synthetic mucins have been used in health applications is discussed. Natural mucins are formed from a conserved set of monomers that are combined into chains of different sequences and lengths to achieve materials with widely diverse properties. Adopting this design paradigm from natural mucins could lead to next-generation bioinspired synthetic materials.

HelixComplex snail mucus as a potential technology against O3 induced skin damage

Mucus form H. aspersa muller has been reported to have several therapeutic proprieties, such as antimicrobial activity, skin protection and wound repair. In this study, we have analyzed H. aspersa mucus (Helixcomplex) bio-adhesive efficacy and its defensive properties against the ozone (O₃) (0.5 ppm for 2 hours) exposure in human keratinocytes and reconstructed human epidermis models. Cytotoxicity, tissue morphology and cytokine levels were determined. We confirmed HelixComplex regenerative and bio-adhesive properties, the latter possibly via the characteristic mucopolysaccharide composition. In addition, HelixComplex was able to protect from O₃ exposure by preventing oxidative damage and the consequent pro-inflammatory response in both 2D and 3D models. Based on this study, it is possible to suggest HelixComplex as a potentially new protective technology against pollution induced skin damage.

Fungal volatile organic compounds show promise as potent molluscicides

BACKGROUND

Slugs and snails constitute major crop pests. Withdrawal of metaldehyde has prompted a search for more environmentally friendly yet fast acting molluscicides. This study investigated the response of representative molluscs to conidia and volatile organic compounds (VOCs) of the insect pathogenic fungus Metarhizium brunneum Petch.

RESULTS

Conidia of M. brunneum had antifeedant/repellent properties with repellency being dependent upon the fungal strain and conidia concentration. Three commonly produced fungal VOCs, 1-octene, 3-octanone and 1-octen-3-ol, were repellent at low doses (1-5 μL) but could kill slugs and snails on contact or fumigation. At the highest dose tested (10 μL), 100% mortality was achieved for Cornu aspersum Muller (garden snail) and Derocerus reticulatum Muller (grey field slug) within 1 h post-treatment with the first deaths being recorded in <11 min. Aqueous formulations (20% v/v) of the most potent VOCs, 3-octanone and 1-octen-3-ol, could be sprayed onto plants to kill or drive the pest of the crop with no phytotoxic effects.

CONCLUSION

The sensitivity of terrestrial molluscs to 3-octanone and 1-octen-3-ol and the ephemeral nature of these compounds makes these excellent candidates for development as mollusc repellents or molluscicides. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

HelixComplex snail mucus exhibits pro-survival, proliferative and pro-migration effects on mammalian fibroblasts

Snail mucus is a mixture of active substances commonly thought to have healthy properties for the treatment of skin disorders. Although snail mucus is an ingredient of several cosmetic and para-pharmaceutic products, a comprehensive characterization of chemical composition and biological effects is still missing. Crude purified extracts from Helix aspersa muller mucus (HelixComplex) were prepared and, after chemical characterization, tested on in vitro experimental models. Differently from what expected, HelixComplex was characterized by the presence of small amounts of glycolic acid and allantoin. By using different in vitro assays on fibroblast cultures, we found that HelixComplex lacked of cytotoxicity, protected cells from apoptosis (p < 0.05) and, importantly, was able to significantly induce cell proliferation and migration through direct and indirect mechanisms. These effects were associated to morphological changes, cytoskeleton re-organization and release of cytokines. In conclusion, our findings suggest that snail mucus biological effects are attributable to cell proliferation and migration, and pave the way for further investigating snail mucus potential as therapeutic agent.

Concentration-independent mechanics and structure of hagfish slime

The defense mechanism of hagfish slime is remarkable considering that hagfish cannot control the concentration of the resulting gel directly; they simply exude a concentrated material into a comparably "infinite" sea of water to form a dilute, sticky, cohesive elastic gel. This raises questions about the robustness of gel formation and rheological properties across a range of concentrations, which we study here for the first time. Across a nearly 100-fold change in concentration, we discover that the gel has similar viscoelastic time-dependent properties with constant power-law exponent (α=0.18±0.01), constant relative damping tanδ=G^''/G^'≈0.2-0.3, and varying overall stiffness that scales linearly with the concentration (∼c^0.99±0.05). The power-law viscoelasticity (fit by a fractional Kelvin-Voigt model) is persistent at all concentrations with nearly constant fractal dimension. This is unlike other materials and suggests that the underlying material structure of slime remains self-similar irrespective of concentration. This interpretation is consistent with our microscopy studies of the fiber network. We derive a structure-rheology model to test the hypothesis that the origins of ultra-soft elasticity are based on bending of the fibers. The model predictions show an excellent agreement with the experiments. Our findings illustrate the unusual and robust properties of slime which may be vital in its physiological use and provide inspiration for the design of new engineered materials.

STATEMENT OF SIGNIFICANCE

Hagfish produce a unique gel-like material to defend themselves against predator attacks. The successful use of the defense gel is remarkable considering that hagfish cannot control the concentration of the resulting gel directly; they simply exude a small quantity of biomaterial which then expands by a factor of 10,000 (by volume) into an "infinite" sea of water. This raises questions about the robustness of gel formation and properties across a range of concentrations. This study provides the first ever understanding of the mechanics of hagfish slime over a very wide range of concentration. We discover that some viscoelastic properties of slime are remarkably constant regardless of its concentration. Such a characteristic is uncommon in most known materials.

Adhesive Leaf Created by a Corona Discharge

Here, we report a new concept of both the adhesive manner and material, named “adhesive leaf (AL),” based on the leaf of the plant Heteropanax fragrans. The treatment of the corona discharge on the leaf surface can cause the nano-/microdestruction of the leaf epidermis, resulting in an outward release of sap. The glucose-containing sap provided the AL with a unique ability to stick to various substrates such as steel, polypropylene, and glass. Moreover, we reveal that the AL adhesion strength depends on the AL size, as well as the corona-discharge intensity. Conventional adhesives, such as glue and bond, lose their adhesive property and leave dirty residues upon the removal of the attached material. Unlike the conventional methods, the AL is advantageous as it can be repeatedly attached and detached thoroughly until the sap liquid is exhausted; its adhesive ability is maintained for at least three weeks at room temperature. Our findings shed light on a new concept of a biodegradable adhesive material that is created by a simple surface treatment.

Controlled self-assembly of glycoprotein complex in snail mucus from lubricating liquid to elastic fiber

Terrestrial snail could intelligently employ elastic fibers clinging itself onto the inverted smooth plate.