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The intricate organization of goethite nanorods within a silica-rich matrix makes limpet teeth the strongest known natural material. However, the mineralization pathway of goethite in organisms under ambient conditions remains elusive. Here, by investigating the multi-level structure of limpet teeth at different growth stages, it is revealed that the growth of goethite crystals proceeds by the attachment of amorphous nanoparticles, a nonclassical crystallization pathway widely observed during the formation of calcium-based biominerals. Importantly, these nanoparticles contain a high amount of silica, which is gradually expelled during the growth of goethite. Moreover, in mature teeth of limpet, the content of silica correlates with the size of goethite crystals, where smaller goethite crystals are densely packed in the leading part with higher content of silica. Correspondingly, the leading part exhibits higher hardness and elastic modulus. Thus, this study not only reveals the nonclassical crystallization pathway of goethite nanorods in limpet teeth, but also highlights the critical roles of silica in controlling the hierarchical structure and the mechanical properties of limpet teeth, thus providing inspirations for fabricating biomimetic materials with excellent properties., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Abalone (Haliotis spp.) is a shellfish known for its exceptional nutritional value and significant economic worth. This study investigated the dynamic characteristics of non-volatile compounds over a year, including metabolites, lipids, nucleotides, and free amino acids (FAAs), which determined the nutritional quality and flavor of abalone. 174 metabolites and 371 lipids were identified and characterized, while 20 FAAs and 11 nucleotides were quantitatively assessed. These non-volatile compounds of abalone were fluctuated with months variation, which was consistent with the fluctuations of environmental factors, especially seawater temperature. Compared with seasonal variation, gender had less influence on these non-volatiles. June and July proved to be the optimal harvesting periods for abalone, with the levels of overall metabolites, lipids, FAAs, and nucleotides in abalone exhibiting a higher value in June and July over a year. Intriguingly, taurine covered 60% of the total FAAs and abalone could be used as dietary taurine supplementation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The slug Arion subfuscus produces a tough, highly adhesive defensive secretion. This secretion is a flexible hydrogel that is toughened by a double network mechanism. While synthetic double network gels typically require extensive time to prepare, this slug creates a tough gel in seconds. To gain insight into how the glue forms a double-network hydrogel so rapidly, the secretory apparatus of this slug was analyzed. The goal was to determine how the major components of the glue were distributed and mixed. Most of the glue comes from two types of large unicellular glands; one secretes polyanionic polysaccharides in small, membrane-bound packets, the other secretes proteins that appear to form a cross-linked network. The latter gland shows distinct regions where cross-linking appears to be occurring. These regions are darker, more homogeneous and appear more solid than the rest of the secretory material. The enzyme catalase is highly abundant in these regions, as are basic proteins. These results suggest that a rapid oxidation event occurs in this protein-containing gland, triggering cross-linking before the glue is released. The cross-linked microgels would then join together after secretion to form a granular hydrogel. The polysaccharide-filled packets would be mixed and interspersed among these microgels and may contribute to joining them together. This is an unexpected and highly effective way to form a tough gel rapidly.

Mollusk hemocyanins, among the largest known proteins, are used as immunostimulants in biomedical and clinical applications. The hemocyanin of the Chilean gastropod Concholepas concholepas (CCH) exhibits unique properties, which makes it safe and effective for human immunotherapy, as observed in animal models of bladder cancer and melanoma, and dendritical cell vaccine trials. Despite its potential, the structure and amino acid sequence of CCH remain unknown. This study reports two sequence fragments of CCH, representing three complete functional units (FUs). We also determined the high-resolution (1.5 Å) X-ray crystal structure of an "FU-g type" from the CCHB subunit. This structure enables in-depth analysis of chemical interactions at the copper-binding center and unveils an unusual, truncated N-glycosylation pattern. These features are linked to eliciting more robust immunological responses in animals, offering insights into CCH's enhanced immunostimulatory properties and opening new avenues for its potential applications in biomedical research and therapies., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Feeding-choice experiments were conducted under laboratory conditions with two dorid spongivorous nudibranchs, Goniobranchus aureomarginatus and Ceratosoma amoenum, collected from a sponge meadow off Tauranga, New Zealand with two sponge prey (Dysidea teawanui sp.nov. and an undescribed species from the Dictyodendrillidae family, possibly Dictyodendrilla tenella (Lendenfeld 1888). The first choice of prey, the total number of prey choices made, and the time spent on each prey target was recorded, results indicating that each nudibranch had strong preferences for specific prey species. Preferences were significant when the time spent grazing on prey was taken into consideration. Goniobranchus aureomarginatus had a strong preference for the undescribed Dictyodendrillid sponge, while Ceratosoma ameonum preferred Dysidea teawanui. The results of the feeding-choice experiments matched observations in the wild. Chemical analysis of the undescribed Dictyodendrillid sponge led to the isolation and characterisation of six known bioactive metabolites, dictyodendrin C (1), D (2) and F (3), as well as denigrin E (4), dactylpyrrole A (5) and lamellarin O1 (6). Two of the known compounds, dictyodendrins C (1) and F (3) were also isolated from G. aureomarginatus individuals. Chemical analysis of D. teawanui afforded ergosterol peroxide, 5α,8α-epidioxy-24-methylcholesta-6,22-dien-3β-ol (7). The structures of the isolated natural products were elucidated based on extensive analysis of 1D and 2D NMR data., (© 2023. The Author(s).)

Hyperpigmentation is a medical and cosmetic problem caused by an excess accumulation of melanin or the overexpression of the enzyme tyrosinase, leading to several skin disorders, i.e., freckles, melasma, and skin cancer. Tyrosinase is a key enzyme in melanogenesis and thus a target for reducing melanin production. Although abalone is a good source of bioactive peptides that have been used for several properties including depigmentation, the available information on the anti-tyrosinase property of abalone peptides remains insufficient. This study investigated the anti-tyrosinase properties of Haliotis diversicolor tyrosinase inhibitory peptides (hdTIPs) based on mushroom tyrosinase, cellular tyrosinase, and melanin content assays. The binding conformation between peptides and tyrosinase was also examined by molecular docking and dynamics study. KNN1 showed a high potent inhibitory effect on mushroom tyrosinase with an IC 50 of 70.83 μM. Moreover, our selected hdTIPs could inhibit melanin production through the reductions in tyrosinase activity and reactive oxygen species (ROS) levels by enhancing the antioxidative enzymes. RF1 showed the highest activity on both cellular tyrosinase inhibition and ROS reduction. leading to the lower melanin content in B16F10 murine melanoma cells. Accordingly, it can be assumed that our selected peptides exhibited high potential in medical cosmetology applications.

The precise mechanism of texture changes in abalone muscles during boiling was investigated using quantitative proteomic analysis. A total 353 water-soluble proteins were identified in fresh abalone muscle. The number was decreased to 233 (6 min) and 201 (30 min), and then increased to 271 (240 min) during boiling. The undetectable protein in water-soluble fraction caused by boiling mainly belong to hemocyanins, protein kinases, dehydrogenases, phosphorylases, and transferases, while the newly identified proteins in water-soluble fraction during boiling mainly belong to collagen and myofibrillar proteins (MPs).Additionally, results also showed that boiling caused protein oxidation, denaturation, aggregation, crosslinking and degradation. Combined with the texture changes of abalone muscles during boiling, it was speculated that the oxidation, denaturation, aggregation and crosslinking of proteins led to the increase of shear force, however, the degradation of structural proteins such as MPs and collagen caused the decreases in shear force and hardness., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Tachykinin (TK) families, including the first neuropeptide substance P, have been intensively explored in bilaterians. Knowledge of signaling of TK receptors (TKRs) has enabled the comprehension of diverse physiological processes. However, TK signaling systems are largely unknown in Lophotrochozoa. This study identified two TK precursors and two TKR isoforms in the Pacific abalone Haliotis discus hannai (Hdh), and characterized Hdh-TK signaling. Hdh-TK peptides harbored protostomian TK-specific FXGXRamide or unique YXGXRamide motifs at the C-termini. A phylogenetic analysis showed that lophotrochozoan TKRs, including Hdh-TKRs, form a monophyletic group distinct from arthropod TKRs and natalisin receptor groups. Although reporter assays demonstrated that all examined Hdh-TK peptides activate intracellular cAMP accumulation and Ca 2+ mobilization in Hdh-TKR-expressing mammalian cells, Hdh-TK peptides with N-terminal aromatic residues and C-terminal FXGXRamide motifs were more active than shorter or less aromatic Hdh-TK peptides with a C-terminal YXGXRamide. In addition, we showed that ligand-stimulated Hdh-TKRs mediate ERK1/2 phosphorylation in HEK293 cells and that ERK1/2 phosphorylation is inhibited by PKA and PKC inhibitors. In three-dimensional in silico Hdh-TKR binding modeling, higher docking scores of Hdh-TK peptides were consistent with the lower EC50 values in the reporter assays. The transcripts for Hdh-TK precursors and Hdh-TKR were highly expressed in the neural ganglia, with lower expression levels in peripheral tissues. When abalone were starved for 3 weeks, Hdh-TK1 transcript levels, but not Hdh-TK2 , were increased in the cerebral ganglia (CG), intestine, and hepatopancreas, contrasting with the decreased lipid content and transcript levels of sterol regulatory element-binding protein ( SREBP ). At 24 h post-injection in vivo , the lower dose of Hdh-TK1 mixture increased SREBP transcript levels in the CG and hepatopancreas and accumulative food consumption of abalone. Higher doses of Hdh-TK1 and Hdh-TK2 mixtures decreased the SREBP levels in the CG. When Hdh - TK2 -specific siRNA was injected into abalone, intestinal SREBP levels were significantly increased, whereas administration of both Hdh - TK1 and Hdh-TK2 siRNA led to decreased SREBP expression in the CG. Collectively, our results demonstrate the first TK signaling system in gastropod mollusks and suggest a possible role for TK peptides in regulating lipid metabolism in the neural and peripheral tissues of abalone., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Lee, Kim, Park, Park and Sohn.)

In the present study, we investigated the shell microstructures of the gastropod European abalone Haliotis tuberculata in order to clarify the complex spatial distribution of the different mineral phases. Our studies were carried out with a standardized methodology on thirty adult European abalone H. tuberculata (5-6 cm long) composed of 15 wild individuals and 15 individuals taken from the France Haliotis hatchery. The macroscopic (binocular) and microscopic observations coupled with Fourier Transform Infrared Spectroscopy (FTIR) and Raman vibrational analysis allowed to unambiguously detect, identify and localize calcite and aragonite. For the first time it has been shown that calcite is present in 100% of farmed and wild adult shell. The microstructural details of the calcite-aragonite interfaces were revealed by using both confocal micro-Raman mapping and Scanning Electron Microscopy (SEM) observations. Calcite zones are systematically found in the spherulitic layer without direct contact with the nacreous layer. The calcite area - nacreous layer interface is made of a thin spherulitic layer with variable thickness from a few micrometers to several millimeters. In order to contribute to a better understanding of the biomineralization process, a model explaining the hierarchical arrangement of the different phases of calcium carbonate is presented and discussed. Finally, it has been shown that these calcitic zones can be connected to each other within the shells and that their spatial distributions correspond to streaks perpendicular to the direction of length growth., (Copyright © 2022. Published by Elsevier Inc.)

In this paper, we investigate the presence of latrunculin A in the outer rim of a nudibranch Chromodoris kuiteri and show that by combining ultrathin cryosection methods with MALDI MSI we can achieve improved lateral ( x and y ) resolution and very high resolution in the z dimension by virtue of the ultrathin 200 nm thin cryosections. We also demonstrate that a post ionization laser increases sensitivity. Recent advances in MALDI source design have improved the lateral resolution ( x and y ) and sensitivity during MSI. Taken together, very high z resolution, from ultrathin sections, and improved lateral ( x and y ) resolution will allow for subcellular molecular imaging with the potential for subcellular 3D volume reconstruction.

The effects of oxidation on protein digestion and transport in cooked abalone muscles were investigated using a combination of simulated digestion and everted-rat-gut-sac models for the first time. Boiling heat treatments caused protein oxidation in the abalone muscles, reflected by increases in the carbonyl group and disulfide bond contents, protein hydrophobicity and aggregation degree, as well as decreases in the free sulfhydryl group and amino acid contents. Protein oxidation significantly inhibited the degree of hydrolysis, digestion rate, and digestibility of the abalone muscles in the simulated digestion model. The results from the everted-rat-gut-sac model showed that amino acid and peptide transport levels from the digestion products of the cooked abalone muscles were lower than those of the uncooked samples. In contrast, the addition of antioxidants of bamboo leaves mitigated heat-treatment-induced protein oxidation, aggregation and increased hydrophobicity, and consequently improved abalone muscle protein digestibility and transport levels.

Liver cancer is a leading cause of cancer death globally. Marine mollusc-derived drugs have gained attention as potential natural-based anti-cancer agents to overcome the side effects caused by conventional chemotherapeutic drugs during cancer therapy. Using liquid chromatography-mass spectrometry, the main biomolecules in the purple ink secretion released by the sea hare, named Bursatella leachii ( B. leachii ), were identified as hectochlorin, malyngamide X, malyngolide S, bursatellin and lyngbyatoxin A. The cytotoxic effects of B. leachii ink concentrate against human hepatocarcinoma (HepG2) cells were determined to be dose- and time-dependent, and further exploration of the underlying mechanisms causing the programmed cell death (apoptosis) were performed. The expression of cleaved-caspase-8 and cleaved-caspase-3, key cysteine-aspartic proteases involved in the initiation and completion of the apoptosis process, appeared after HepG2 cell exposure to the B. leachii ink concentrate. The gene expression levels of pro-apoptotic BAX , TP53 and Cyclin D1 were increased after treatment with the B. leachii ink concentrate. Applying in silico approaches, the high scores predicted that bioactivities for the five compounds were protease and kinase inhibitors. The ADME and cytochrome profiles for the compounds were also predicted. Altogether, the B. leachii ink concentrate has high pro-apoptotic potentials, suggesting it as a promising safe natural product-based drug for the treatment of liver cancer.

Metallothioneins' (MTs) biological function has been a matter of debate since their discovery. The importance to categorize these cysteine-rich proteins with high coordinating capacity into a specific group led to numerous classification proposals. We proposed a classification based on their metal-binding abilities, gradually sorting them from those with high selectivity towards Zn/Cd to those that are Cu-specific. However, the study of the NpeMT1 and NpeMT2isoforms of Nerita peloronta , has put a new perspective on this classification. N. peloronta has been chosen as a representative mollusk to elucidate the metal-binding abilities of Neritimorpha MTs, an order without any MTs characterized recently. Both isoforms have been recombinantly synthesized in cultures supplemented with Zn II , Cd II , or Cu II , and the purified metal-MT complexes have been thoroughly characterized by spectroscopic and spectrometric methods, leading to results that confirmed that Neritimorpha share Cd-selective MTs with Caenogastropoda and Heterobranchia, solving a so far unresolved question. NpeMTs show high coordinating preferences towards divalent metal ions, although one of them (NpeMT1) shares features with the so-called genuine Zn-thioneins, while the other (NpeMT2) exhibits a higher preference for Cd. The dissimilarities between the two isoforms let a window open to a new proposal of chemical MT classification.

Due to potential side effects of current drugs in colitis treatment, polysaccharides with anti-inflammatory activities can be considered as alternative molecules for colitis treatment. Sulfated polysaccharide from pacific abalone (AGSP) reduced the level of lipopolysaccharides (LPS) and increased the production of short chain fatty acids in the colon of mice, and it reduced the levels of interleukin (IL)-6, IL-1β and tumor necrosis factor (TNF)-α and increased the IL-10 level in in vitro cell models, suggesting that it can be used as a probiotic agent to inhibit intestinal inflammation. Furthermore, AGSP reduced the disease activity index and intestinal damage, improved the mucosal immune response, and inhibited oxidative damage in mice with DSS-induced acute and chronic colitis, which can be associated with modulation of the NF-κB signaling pathway and gut microbiota. AGSP regulated the structure of the gut microbiota and reduced the level of Bacteroides that had positive correlation with the colitis symptoms. The in vitro result showed that AGSP may inhibit mucin degradation by Bacteroides via the change of the polysaccharide utilization strategy, which can protect intestinal barrier integrity. This study is useful to understand the mechanism by which AGSP ameliorates colitis and related diseases and promotes further development of AGSP.

Many organisms employ toxic compounds for protection against predators. To understand the effectiveness of such compounds, chemoecological studies often use brine shrimp (Artemia spp.) as a model organism instead of more ecologically relevant species. This is mostly because brine shrimp assays are simple and quick, but also due to the ethical implications associated with inducing harm to vertebrate predators in toxicity assays. In this study, we examined whether brine shrimp assays produce similar results to ichthyological toxicity assays with the aim of validating the use of brine shrimp as a preliminary screening tool. We extracted compounds from eight nudibranch molluscs including six species that we consider to signal their chemical defenses via warning coloration to visually hunting vertebrate predators. We tested the relative toxicity of these compounds against brine shrimp and a vertebrate potential predator, the blue-green damselfish (Chromis viridis). We found that extracts toxic to brine shrimp were also toxic to damselfish; however, extracts non-toxic to brine shrimp may still be toxic to damselfish. We also produced and tested mantle vs whole-body extracts for some nudibranch species, which exhibited similar toxicities in both assays except for the whole-body extract of Goniobranchus splendidus which was harmless to shrimp but toxic to fish, while the mantle extract was toxic to both. Overall, we argue that the brine shrimp assay can reasonably indicate the potential toxicity of a compound to fish, but additional experiments with more ecologically relevant predators are required if a no dose-response is observed against brine shrimp., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The crude polysaccharides (NLCEP) were extracted from Notarchus leachii freeri eggs strings by the saltextractionmethod. The extraction conditions were optimized using the single-factorexperimentmethod and response surface method (RSM). The results showed that the maximum extraction yield of NLCEP was obtained under the following conditions: NaCl solution concentration of 2.96 %, raw material to liquid ratio of 1: 40 g/mL, extraction time of 2 h and extraction temperature of 69 °C. A new novel pure polysaccharide fraction named as NLCEPs-1 was fractionated from NLCEP by using DEAE-Cellulose 52 and Sephadex G-100. Its structure and immunomodulatory and antioxidant activities were analyzed. The results exhibited that the molecular weight of NLCEPs-1 was 31.4 kDa and it was composed of rhamnose, glucose, galactose, xylose and arabinose in the molar percentage of 11.128: 63.770: 5.439: 6.585: 13.077. The backbone of NLCEPs-1 was mainly consisted of → )4-α-d-Glcp (1→, →6)-α-d-Glcp (1→, →1)-β-d-Galp and β-d-Galp-(1→. NLCEPs-1 exhibited the strong antioxidant activity in scavenging ability of various free radicals and immunomodulatory activity by the enhancement of the pinocytic capacity, nitric oxide (NO) and cytokines., (Copyright © 2021. Published by Elsevier Inc.)

We assessed metal/metalloid pollutants (through multi-indices) in seawater, sediments, tissues and shells of gastropods using various indices such as contamination degree (modified/unmodified; Cd/mCd; 1875/187.5). From sediment indices; e.g. the potential ecological risk index/enrichment factor (Eri/EF; 3396.8/105.5) indicated the area to be highly contaminated with metal/metalloid pollutants. Indeed, bioaccumulation with these materials was gastropod size dependent. Antimicrobial and percentage activity indices (AMI/PAI) for; T. telescopium was (AMI/PAI; 1.59/159), N. albicilla (1.14/114) and L. coronata (0.95/95) against E. coli. Similarly T. telescopium (1.33/133), N. albicilla (1.19/119) and L. coronata (1.14/114) have AMI/PAI against A. terreus. The total activity index (TAI), for T. telescopium was the highest, while L. coronata has lowest for all pathogens. This study indicates, T. telescopium, N. albicilla and L. coronata, surviving under metal/metalloid stress exhibited altered natural defense to pathogens which was related to the degree of toxin bioaccumulation., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This study aims to investigate effects of ultrasound assisted extraction on the abalone viscera protein extraction rate and iron-chelating activity of peptides. The optimal conditions for ultrasound assisted extraction by response surface methodology was at sodium hydroxide concentration 14 g/kg, ultrasonic power 428 W and extraction time 52 min. Under the optimal conditions, protein extraction rate was 64.89%, compared with alkaline extraction of 55.67%. The iron-chelating activity of peptides affected by ultrasound technology was further evaluated by iron-chelating rate, FTIR spectroscopy and LC-HRMS/MS. Alcalase was the suitable enzyme for the preparation of iron-chelating peptides from two abalone viscera proteins, showing no significant difference between their iron-chelating rate of 16.24% (ultrasound assisted extraction) and 16.60% (alkaline extraction). Iron binding sites from the two hydrolysates include amino and carboxylate terminal groups and peptide bond of the peptide backbone as well as amino, imine and carboxylate from side chain groups. Moreover, 24 iron-chelating peptides were identified from hydrolysate (alcalase, ultrasound assisted extraction), which were different from the 27 iron-chelating peptides from hydrolysate (alcalase, alkaline extraction). This study suggests the application of ultrasound technology in the generation of abalone viscera-derived iron-chelating peptides which have the ability to combat iron deficiency., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Skin pigment disorders are common cosmetic and medical problems. Many known compounds inhibit the key melanin-producing enzyme, tyrosinase, but their use is limited due to side effects. Natural-derived peptides also display tyrosinase inhibition. Abalone is a good source of peptides, and the abalone proteins have been used widely in pharmaceutical and cosmetic products, but not for melanin inhibition. This study aimed to predict putative tyrosinase inhibitory peptides (TIPs) from abalone, Haliotis diversicolor , using k-nearest neighbor (kNN) and random forest (RF) algorithms. The kNN and RF predictors were trained and tested against 133 peptides with known anti-tyrosinase properties with 97% and 99% accuracy. The kNN predictor suggested 1075 putative TIPs and six TIPs from the RF predictor. Two helical peptides were predicted by both methods and showed possible interaction with the predicted structure of mushroom tyrosinase, similar to those of the known TIPs. These two peptides had arginine and aromatic amino acids, which were common to the known TIPs, suggesting non-competitive inhibition on the tyrosinase. Therefore, the first version of the TIP predictors could suggest a reasonable number of the TIP candidates for further experiments. More experimental data will be important for improving the performance of these predictors, and they can be extended to discover more TIPs from other organisms. The confirmation of TIPs in abalone will be a new commercial opportunity for abalone farmers and industry.

Chromene derivatives with manifold structural framework and pharmacological properties were ubiquitous in the mollusks of marine origin. A previously undescribed 1 H -benzochromenone was isolated through bioassay-guided chromatographic purification of the organic extract of the marine gastropod mollusk Chicoreus ramosus . The compound was characterised as 6-(2',2'-dimethyl)-3'-en-1'-yl-1'-oxy)-3-hydroxy-1 H -benzo[c]chromene-2(10a H )-one based on integrated spectroscopic analysis. The antioxidant studies by employing the stable free radicals reported that the antioxidant activity (IC 50 1.4-1.6 mM) was comparable to α -tocopherol (IC 50 1.4-1.7 mM). The attenuating potential of the studied compound against pro-inflammatory 5-lipoxygenase (IC 50 2.12 mM) was significantly greater than that exhibited by anti-inflammatory drug ibuprofen (IC 50 4.4 mM), whereas its inhibitory properties against carbolytic α -amylase (IC 50 ∼0.72 mM) was comparable with that displayed by acarbose (IC 50 0.43 mM). The present study recognised the potential of 1 H -benzochromenone derivative isolated from C. ramosus as important pharmaceutical lead with anti-diabetic and anti-inflammatory potentials to reduce the risk of hyperglycaemia and inflammatory pathologies.

Marine biodiversity has been yielding promising novel bioproducts from venomous animals. Despite the auspices of conotoxins, which originated the paradigmatic painkiller Prialt, the biotechnological potential of gastropod venoms remains to be explored. Marine bioprospecting is expanding towards temperate species like the dogwhelk Nucella lapillus , which is suspected to secrete immobilizing agents through its salivary glands with a relaxing effect on the musculature of its preferential prey, Mytilus sp. This work focused on detecting, localizing, and testing the bioreactivity of cysteine-rich proteins and peptides, whose presence is a signature of animal venoms and poisons. The highest content of thiols was found in crude protein extracts from the digestive gland, which is associated with digestion, followed by the peribuccal mass, where the salivary glands are located. Conversely, the foot and siphon (which the gastropod uses for feeding) are not the main organs involved in toxin secretion. Ex vivo bioassays with Mytilus gill tissue disclosed the differential bioreactivity of crude protein extracts. Secretions from the digestive gland and peribuccal mass caused the most significant molecular damage, with evidence for the induction of apoptosis. These early findings indicate that salivary glands are a promising target for the extraction and characterization of bioactive cysteine-rich proteinaceous toxins from the species.

Much attention is being devoted to the potential of marine sulfated polysaccharides as antiviral agents in preventing COVID-19. In this study, sulfated fucoidan and crude polysaccharides, extracted from six seaweed species (Undaria pinnatifida sporophyll, Laminaria japonica, Hizikia fusiforme, Sargassum horneri, Codium fragile, Porphyra tenera) and Haliotis discus hannai (abalone viscera), were screened for their inhibitory activity against SARS-CoV-2 virus entry. Most of them showed significant antiviral activities at an IC50 of 12~289 μg/mL against SARS-CoV-2 pseudovirus in HEK293/ACE2, except for P. tenera (IC50 > 1000 μg/mL). The crude polysaccharide of S. horneri showed the strongest antiviral activity, with an IC50 of 12 μg/mL, to prevent COVID-19 entry, and abalone viscera and H. fusiforme could also inhibit SARS-CoV-2 infection with an IC50 of 33 μg/mL and 47 μg/mL, respectively. The common properties of these crude polysaccharides, which have strong antiviral activity, are high molecular weight (>800 kDa), high total carbohydrate (62.7~99.1%), high fucose content (37.3~66.2%), and highly branched polysaccharides. These results indicated that the crude polysaccharides from seaweeds and abalone viscera can effectively inhibit SARS-CoV-2 entry.

Tetrodotoxin (TTX) is a potent neurotoxin, considered an emerging toxin in Europe where recently a safety limit of 44 µg TTX kg -1 was recommended by authorities. In this study, three specimens of the large gastropod trumpet shell Charonia lampas bought in a market in south Portugal were analyzed using a neuroblastoma cell (N2a) based assay and by LC-MS/MS. N2a toxicity was observed in the viscera of two individuals analyzed and LC-MS/MS showed very high concentrations of TTX (42.1 mg kg -1 ) and 4,9-anhydroTTX (56.3 mg kg -1 ). A third compound with m/z 318 and structurally related with TTX was observed. In the edible portion, i.e., the muscle, toxin levels were below the EFSA recommended limit. This study shows that trumpet shell marine snails are seafood species that may reach the markets containing low TTX levels in the edible portion but containing very high levels of TTX in non-edible portion raising concerns regarding food safety if a proper evisceration is not carried out by consumers. These results highlight the need for better understanding TTX variability in this gastropod species, which is critical to developing a proper legal framework for resources management ensuring seafood safety, and the introduction of these gastropods in the markets.

Metabolomics analysis detected tambjamine alkaloids in aqueous and EtOAc extracts of the marine invertebrates Virididentula dentata , Tambja stegosauriformis , Tambja brasiliensis , and Roboastra ernsti . Among several tambjamines, the new amino acid derivatives tambjamines M-O ( 17 - 19 ) were identified by Marfey's advanced analysis, UPLC-MS/MS analyses, and total synthesis. The tambjamine diversity increased from the bryozoan V. dentata to its nudibranch predators T. stegosauriformis and T. brasiliensis and attained a higher diversity in R. ernsti , the nudibranch that preys upon T. stegosauriformis and T. brasiliensis . The total tambjamine content also increases among the trophic levels, probably due to biomagnification. Tambjamines A ( 1 ), C ( 3 ), and D ( 4 ) are the major metabolites in the tissues of V. dentata , T. stegosauriformis , T. brasiliensis , and R. ernsti and are likely the main chemical defenses of these marine invertebrates.

Novel biocompatible compounds that stabilize proteins in solution are in demand for biomedical and/or biotechnological applications. Here, we evaluated the effect of six ionic liquids, containing mono- or dicholinium [Chol] 1or2 cation and anions of charged amino acids such as lysine [Lys], arginine [Arg], aspartic acid [Asp], or glutamic acid [Glu], on the structure, thermal, and storage stability of the Rapana thomasiana hemocyanin (RtH). RtH is a protein with huge biomedicinal potential due to its therapeutic, drug carrier, and adjuvant properties. Overall, the ionic liquids (ILs) induce changes in the secondary structure of RtH. However, the structure near the Cu-active site seems unaltered and the oxygen-binding capacity of the protein is preserved. The ILs showed weak antibacterial activity when tested against three Gram-negative and three Gram-positive bacterial strains. On the contrary, [Chol][Arg] and [Chol][Lys] exhibited high anti-biofilm activity against E. coli 25213 and S. aureus 29213 strains. In addition, the two ILs were able to protect RtH from chemical and microbiological degradation. Maintained or enhanced thermal stability of RtH was observed in the presence of all ILs tested, except for RtH-[Chol] 2 [Glu].

We report the electron microscopy-based analysis of the major lateral tooth of the limpet Colisella subrugosa during early and intermediate stages of development. We aimed to analyze the structural relationship among the needle-like crystals of the iron oxide goethite, the amorphous silica phase that forms the tooth base and occupy inter-crystalline spaces in the cusp, and the chitin fibers of the matrix. Goethite crystals followed the three dimensional organization pattern of the chitin fibers in the cusp. In the tooth base, spherical individual silica granules were found in regions where the chitin fibers cross. The spherical granules near the interface between the tooth base and the cusp (junction zone) formed an almost continuous medium that could easily be ultrathin-sectioned for further analysis. By contrast, the nearby silica-rich region localized on the other side of the junction zone contained needle-like goethite crystals immersed in the matrix and presented a conchoidal fracture. The chitin fibers from the silica granules of the tooth base were dotted or undulating in projection with a periodicity of about 6 nm when observed by high magnification transmission electron microscopy. Very thin goethite crystals were present in the base of the cusp near the junction zone surrounded by silica. On several occasions, crystals presented internal thin straight white lines parallel to the major axis, indicating a possible growth around fibers. We propose that silica and iron oxide phases mineralization may occur simultaneously at least for some period and that silica moderates the dimensions of the iron oxide crystals., (Copyright © 2020. Published by Elsevier Inc.)

The Onchidium genus (Mollusca, Gastropoda, Pulmonata, Systellommatophora, Onchidiidae family) is used as the important economical shellfish, due to the high nutritional value and medicinal value. Research over the previous decades indicated that Onchidium sp. mainly contains polypropionates, depsipeptides, terpenoids and other chemical components. Many biological activities of Onchidium (e. g., cytotoxic activities against tumor cells, anti-viral and anti-bacterial activities) have been reported. This review reports a total of 60 compounds, synthetic work and biological studies on Onchidium genus, covering the literature from 1978 to date, with a view to providing a reference and helping for the in-depth research of this genus., (© 2020 Wiley-VHCA AG, Zurich, Switzerland.)

A mannose binding lectin (C-type lectin) was detected in a molluscan snail Hemifusus pugilinus, this lectin molecule was isolated and purified from the plasma using mannose-fixed sepharose CL-4B column affinity chromatography. The purified protein corresponds to the molecular weight of 118 kDa on an SDS-PAGE gel. The divalent cation-dependent nature of the H. pugilinus lectin (Hp-Lec) evidenced through pH and thermal stability analysis using Circular Dichroism (CD) and Surface Plasmon Resonance (SPR) respectively. Functional investigations of the Hp-Lec reveal a broad spectrum of bacterial agglutination activity against wide range of Gram-positive and Gram-negative bacterial strains. Furthermore, Hp-Lec displayed the haemo agglutination activity against vertebrate red blood cells (RBCs) and its titers were recorded. Excitingly, microbial virulent pathogens such as fungal strains tested against the purified Hp-Lec (25 and 50 μg/ml), which exhibits the effective antifungal activity against tested fungal pathogens such as Aspergillus niger and A. flavus., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Consumption of seafood is a common route of cadmium ion (Cd 2+ ) exposure to consumers. The seafood matrices may alter the toxicity profile of Cd 2+ due to the interaction between Cd 2+ and biomacromolecules in seafood. In this study, enhanced cytotoxicity of Cd 2+ was found in the presence of an abalone gonad sulfated polysaccharide (AGSP) and the mechanism was investigated at a metabolic level. The formation of the AGSP-Cd 2+ complex was demonstrated by isothermal titration calorimetry. The level of reactive oxygen species (ROS) increased and mitochondrial membrane potential reduced upon exposure to the AGSP-Cd 2+ complex as compared with those of Cd 2+ exposure. The decreased cell viability after incubation with the AGSP-Cd 2+ complex also suggested enhanced Cd 2+ toxicity induced by AGSP. The metabolomics and lipidomics analysis revealed that, compared with the Cd 2+ group, the AGSP-Cd 2+ downregulated the phospholipid metabolism and resulted in more serious damage in the cellular membrane. The lipid metabolism disorder, in turn, amplified the generation of ROS, leading to a decrease in cell viability. These results provided new evidence of the enhanced Cd 2+ toxicity upon interaction with seafood polysaccharides, and much attention should be paid to the effect of food ingredients on heavy metal ion toxicity.

Paramyosin (PM) is an important structural protein in molluscan muscles. However, as an important allergen, there is a little information on PM in the molluscs. In this study, a 99 kDa molecular weight allergen protein was purified from Rapana venosa and confirmed as PM by mass spectrometry. The results of immunoglobulin E (IgE)-binding activity and physicochemical characterization showed that R. venosa PM could react with a specific IgE of the sera from sea snail-allergic patients, and the IgE-binding activity could be reduced by thermal treatment. The full-length cDNA of R. venosa PM was cloned, which encodes 859 amino acid residues, and it has a higher homology among molluscan species. According to the circular dichroism results, Fourier transform infrared, and 2D and 3D structure analysis, both PM and tropomyosin are conserved proteins, which are mainly composed of the α-helix structure. These results are significant for better understanding the anaphylactic reactions in sea snail-allergic patients and allergy diagnosis.

Abalone viscera were byproducts of the abalone processing and usually discarded as wastes. In this study, we tried to obtain functional polysaccharides from abalone viscera by a combination of enzymatic hydrolysis, membrane separation, anion exchange chromatography, and gel filtration techniques. Abalone viscera underwent successive hydrolyzation with alcalase and flavourzyme. Each enzymolysis was followed by deproteinization via membrane separation. The final yield of crude abalone viscera polysaccharide (CAVP) was 19.72%; the polysaccharide content of CAVP was 51.75%. Furthermore, three fractions of polysaccharides (AVP1, AVP2, and AVP3) were isolated from the CAVP by anion exchange chromatography and gel filtration. The molecular weights of each AVP were 14.99 kDa, 58.48 kDa, and 39.63 kDa, with a carbohydrate content of 62.75, 23.09, and 44.67%, respectively. These AVPs showed excellent antioxidant activities in vitro. Our results provide a scientific basis for the further utilization of polysaccharides from abalone viscera. PRACTICAL APPLICATION: This study demonstrated an eco-friendly approach for industrial production of high purity animal-derived polysaccharides without any environmental pollution caused by the viscera waste of abalone and promoting the comprehensive utilization of abalone resources., (© 2020 Institute of Food Technologists®.)

Sacoglossan sea slugs are able to maintain functional chloroplasts inside their own cells, and mechanisms that allow preservation of the chloroplasts are unknown. We found that the slug Elysia timida induces changes to the photosynthetic light reactions of the chloroplasts it steals from the alga Acetabularia acetabulum . Working with a large continuous laboratory culture of both the slugs (>500 individuals) and their prey algae, we show that the plastoquinone pool of slug chloroplasts remains oxidized, which can suppress reactive oxygen species formation. Slug chloroplasts also rapidly build up a strong proton-motive force upon a dark-to-light transition, which helps them to rapidly switch on photoprotective non-photochemical quenching of excitation energy. Finally, our results suggest that chloroplasts inside E. timida rely on oxygen-dependent electron sinks during rapid changes in light intensity. These photoprotective mechanisms are expected to contribute to the long-term functionality of the chloroplasts inside the slugs., Competing Interests: VH, ET No competing interests declared, (© 2020, Havurinne and Tyystjärvi.)

Phyllidiid nudibranchs are brightly colored gastropod mollusks, frequently encountered in coral reefs of the tropical Indo-Pacific. The lack of a protective shell is suggested to be compensated by toxic secondary metabolites that are sequestered from specific prey sponges. Our ongoing reconstruction of phyllidiid phylogeny using molecular data of more than 700 specimens, based on published data and newly collected specimens in various seasons and localities around North Sulawesi (Indonesia), demonstrates that Phyllidiella pustulosa is a species complex with at least seven well-supported clades. A metabolomic analysis of 52 specimens from all seven clades of P. pustulosa was performed. Secondary metabolite profiles were found to correlate with the phylogenetic study and not the prevailing food sponges as expected. GNPS molecular networking revealed a unique chemotype in clade 6. Detailed chemical analysis of a specimen from this chemically and genetically distinct P. pustulosa clade led to the identification of seven new sesquiterpenoids with a rare dichloroimidic moiety ( 1 and 4 ) and derivatives thereof ( 2 , 3 , 5 - 7 ). Our findings suggest that P. pustulosa clades should be raised to the species level.

The biosynthetic gene cluster governing the production of antibacterial julichromes was identified from marine gastropod mollusk-associated Streptomyces sampsonii SCSIO 054. Post-PKS assembly/tailoring enzymes JuiL, JuiM, JuiI, and JuiN represent key assembly enzymes. JuiL serves as a ketoreductase. JuiM is an acetyltransferase. JuiI carries out an intriguing biaryl coupling of two julichrome Q 6 units (immediate JuiL, JuiM product) to afford julichrome Q 6-6 . JuiN carries out tailoring steps on julichrome Q 6-6 , transforming Q 6-6 into Q 3-3 .

The present study evaluated the structural and ultrastructural characteristics of Rapana venosa egg capsules, starting from observations of their antifouling activity and mechanical resistance to water currents in mid-shore habitats. Optical microscopy, epifluorescence, and electron microscopy were used to evaluate the surface and structure of the R. venosa egg capsules. These measurements revealed an internal multilamellar structure of the capsule wall with in-plane distributions of layers with various orientations. It was found that the walls contained vacuolar structures in the median layer, which provided the particular characteristics. Mechanical, viscoelastic and swelling measurements were also carried out. This study revealed the presence and distribution of chitosan in the capsule of R. venosa. Chitosan identification in the egg capsule wall structure was carried out through SEM-EDX measurements, colorimetric assays, FT-IR spectra and physical-chemical tests. The biopolymer presence in the capsule walls may explain the properties of their surfaces as well as the mechanical resistance of the capsule and its resistance to chemical variations in the living environment.

The knowledge of relationships between taxa is essential to understand and explain the chemical diversity of the respective groups. Here, twelve individuals of the panpulmonate slug Peronia persiae from two localities in Persian Gulf, and one animal of P. verruculata from Bangka Island, Indonesia, were analyzed in a phylogenetic and chemotaxonomic framework. Based on the ABGD test and haplotype networking using COI gene sequences of Peronia specimens, nine well-supported clades were found. Haplotype network analysis highlighted a considerable distance between the specimens of P. persiae and other clades. Metabolomic analysis of both species using tandem mass spectrometry-based GNPS molecular networking revealed a large chemical diversity within Peronia of different clades and localities. While P. persiae from different localities showed a highly similar metabolome, only few identical chemical features were found across the clades. The main common metabolites in both Peronia species were assigned as polypropionate esters of onchitriols and ilikonapyrones, and osmoprotectant amino acid-betaine compounds. On the other hand, the isoflavonoids genistein and daidzein were exclusively detected in P. persiae, while cholesterol and conjugated chenodeoxycholic acids were only found in P. verruculata. Flavonoids, bile acids, and amino acid-betaine compounds were not reported before from Onchidiidae, some are even new for panpulmonates. Our chemical analyses indicate a close chemotaxonomic relation between phylogeographically distant Peronia species.

The chemical analyses of ethyl acetate-methanol (EtOAc-MeOH) extract of muricid gastropod mollusk, Chicoreus ramosus from the southeastern coast of Indian peninsular led to the identification of unprecedented cembrane-type diterpenoid, which was characterized as (3 E , 6 E , 10 E )-8a-butoxy-17(15→14), 20(12→11)-bis-abeo-cembra-3,6,10,14(17),15-pentaene ( 1 ). The structure of the studied cembrane was unambiguously assigned through the extensive spectroscopic experimentations. The antioxidant potentials of the bis-abeo cembrane as determined by in vitro 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiozoline-6-sulfonic acid diammonium salt radical quenching potentials were greater (IC 50  < 0.40 mg/mL) related to α -tocopherol (IC 50  > 0.60 mg/mL). The pro-inflammatory anti-5-lipoxygenase potential of studied cembrane was higher (IC 50  < 0.80 mg/mL) related to those demonstrated by ibuprofen and sodium salicylate (IC 50  > 0.90 mg/mL).

The aim of this paper was to investigate the extraction, purification and characterization of sulphated polysaccharide (BQPS) from Bellamya quadrata and its stabilization roles on atherosclerotic plaque. Firstly, crude polysaccharide (CBQP) from Bellamya quadrata was extracted by protease enzyme assisted extraction. Moreover, its optimal parameters were obtained by the response surface method as follows: the ratio of water to raw material of 24:1, enzyme dosage of 285 U/g, enzymolysis pH value of 4.7 and temperature of 67 °C. Secondly, CBQP was further purified to obtain the target polysaccharide BQPS by Q Sepharose Fast Flow and Sephacryl S-400 gel column chromatography. Then, the characterization of BQPS revealed that it possessed a total polysaccharide content of 91.88 ± 1.23%, sulfuric acid group content of 9.12 ± 1.59% and molecular weight of 91.1 kDa. BQPS was only consisted of glucose without any proteins. Finally, BQPS was confirmed to have a significant stabilizing effect on atherosclerotic plaque and its mechanism was related to the selective promotion of autophagy with the precisely right strength., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, to obtain further information on the structural diversity of non-methylene-interrupted (NMI) fatty acids (FA) in the gonads of the limpet Cellana toreuma, previously unreported minor NMI FA, fractionated by argentation thin-layer chromatography (TLC), in the ovaries were characterized by gas chromatography-mass spectrometry (GC-MS) analysis of their 3-pyridylcarbinol derivatives. As a result, five novel NMI FA were identified as 5,14-pentadecadienoic acid (15: 2Δ5,14), 5,9,18-nonadecatrienoic acid (19:3Δ5,9,18), 5,9,20-heneicosatrienoic acid (21:3Δ5,9,20), 7,13,20-heneicosatrienoic acid (21:3Δ7,13,20), and 5,9,22-tricosatrienoic acid (23:3Δ5,9,22). Possible biosynthetic pathways for these FA are also discussed in relation to structural variations of NMI FA regioisomers. This study clearly reinforces the findings of our previous works with structurally diverse NMI FA with a terminal double bond., (© 2020 AOCS.)

An automated, high-capacity, and high-throughput procedure for the rapid isolation and identification of biologically active natural products from a prefractionated library is presented. The semipreparative HPLC method uses 1 mg of the primary hit fraction and produces 22 subfractions in an assay-ready format. Following screening, all active fractions are analyzed by NMR, LCMS, and FTIR, and the active principle structural classes are elucidated. In the proof-of-concept study, we show the processes involved in generating the subfractions, the throughput of the structural elucidation work, as well as the ability to rapidly isolate and identify new and biologically active natural products. Overall, the rapid second-stage purification conserves extract mass, requires much less chemist time, and introduces knowledge of structure early in the isolation workflow.

The bioaccessibility of total arsenic (tAs) and arsenic species in Bellamya aeruginosa collected from Xiangjiang River was evaluated using an in vitro digestion model, to assess the potential health risks to local residents. The tAs concentrations in gastropod samples ranged from 1.98 to 6.33 mg kg -1 (mean 3.79 ± 1.60 mg kg -1 ). Five arsenic species including arsenite [As(III)], arsenate [As(V)], dimethylarsinic acid (DMA), arsenobetaine (AsB), and arsenocholine (AsC) were detected. Inorganic arsenic (iAs) concentrations, which were about a half of organic arsenic (oAs), were higher than the maximum permissible limit (≤0.50 mg kg -1 in aquatic products). Bioaccessible concentrations of tAs in digestive juices were found to be decreased in the order: intestinal phase > gastric phase > salivary phase. As(III) and AsC were the predominant species, but AsB was not detectable in all digestive juices. Bioaccessible iAs concentrations, which were close to the level of bioaccessible oAs, were not significantly different among three digestive juices, but also above 0.50 mg kg -1 . Accordingly, bioaccessibility of tAs was highest in intestinal phase (48%), then in gastric phase (40%), and lowest in salivary phase (33%). Bioaccessibility of As(III) was close to 100%, and bioaccessibility of iAs was much higher than that of oAs. The mean values of target hazard quotient (THQ) and bioaccessible THQ were 0.80 and 0.70, respectively. The probability of experiencing non-carcinogenic effects was reduced to 18% down from 22% as considering iAs bioaccessibility. The mean values of carcinogenic risk (CR) and bioaccessible CR were higher than the acceptable value (1 × 10 -4 ). Gastropod consumption from sampling sites may cause a potential carcinogenic risk., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Charcoal production activities at the Matang Mangrove Forest Reserve (MMFR) in Peninsular Malaysia have a potential to emit volatile compounds such as Hg back into the ambient environment, raising concerns on the public health and safety. The present study was aimed at analyzing Hg concentration from different plant/animal tissues and sediment samples (in total 786 samples) to understand clearly the Hg distribution at the MMFR. Leaves of Rhizophora spp. showed higher Hg concentration with an increasing trend from young, to mature, to senescent and decomposing stages, which was possibly due to accumulation of Hg over time. The low Hg concentration in Rhizophora roots and bark suggests a limited absorption from the sediments and a meagre accumulation/partitioning by the plant tissue, respectively. In the case of mangrove cockles the concentration of Hg was lower than the permissible limits for seafood consumption. Although the mangrove gastropod - Cassidula aurisfelis Bruguière had rather elevated Hg in the muscle tissue, it is still less than the environmental safely limit. Beside the chances of atmospheric deposition for Hg, the sediment samples were found to be unpolluted in nature, indicating that in general the MMFR is still safe in terms of Hg pollution., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The South African abalone Haliotis midae is a commercially important species farmed at high densities in land-based aquaculture systems. Disease outbreaks have had a severe financial impact on the abalone industry yet the molecular mechanisms underlying the immune response of H. midae remain obscure. In this study, a comparative shotgun proteomics approach using iTRAQ coupled with LC-MS/MS was employed to investigate H. midae proteome changes in response to Vibrio anguillarum challenge. A total of 118 non-redundant, unique haemocyte proteins were identified and quantified, with 16 proteins significantly regulated. Hierarchical clustering and pathway analysis uncovered a coordinated response dominated by calcium and cAMP signalling via activation of MAPK cascades. Early up-regulated biological processes involve phagocytosis, nitric oxide production and ATP-synthesis, whilst down-regulated responses were predominantly involved in the regulation of apoptosis. The late up-regulated response involved protein kinase activity and detoxification processes. Expression of selected proteins was validated by Western blot. A putative allograft inflammatory factor-1 protein was further selected to establish its functional molecular role in haemocytes. Confocal imaging revealed that allograft inflammatory factor-1 regulates phagocytosis via a functional interaction with filamentous actin. This is the first time a high-throughput proteomics approach has been used to investigate the immune response of H. midae., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Occurrence of traditional (PBDEs) and novel (HBB, PBEB, DBDPE) brominated flame retardants, as well as the natural compounds of MeO-PBDEs, were studied in a shellfish species (Hexaplex trunculus) sampled from Bizerte Lagoon. PBDE and MeO-PBDE mean concentrations in murex soft tissues were 187 and 264 ng g -1  lw respectively. The alternative flame retardants were not identified. The sum of PBDE and MeO-PBDE levels recorded in murex from the investigated aquatic ecosystem were comparable or a relatively lower than those reported for other organisms from other regions across the world. The amount of PBDE and MeO-PBDE concentrations from the Bizerte Lagoon recorded in murex were comparable or a relatively lower than those recorded from other areas across the world for other species. There is not a danger to the population health with regard to PBDE intakes associated with the consumption of murex in Bizerte city. We believe that this is the first study of the analysis of these pollutants in marine gastropod mollusks from Tunisian aquatic areas.

Two new oxygenated terpenes ( 1 and 2 ) have been characterized from the Australian nudibranch Goniobranchus coi . Broadened 1 H NMR signals, together with the absence of individual carbon NMR signals, complicated analysis of 5,9-epoxydendrillolide A ( 1 ); increasing the temperature to 323 K revealed the missing NMR signals. Low-temperature 1 H NMR experiments provided an activation barrier of ∼15 kcal mol -1 and, together with DFT calculations, supported interconversion of a twist chair conformer with two different chair conformers. X-ray crystallographic analysis coupled with biosynthetic reasoning suggested a (5 R , 8 S , 9 R , 13 R , 14 R , 15 R , 16 R ) configuration. Ketone 2 demonstrated similar dynamic conformational processes to 1 .

The chemical compositions and nutritional values of the water-soluble fraction (WF), myofibrillar protein (MP), and stroma protein (SP) from abalone muscle were investigated. The protein, carbohydrate, lipid, and ash contents of abalone muscle were 15.87, 6.36, 0.22, and 1.36 g/100 g, respectively. Most of the carbohydrates in the abalone muscle were released easily into water, and potassium was the most abundant mineral. WF and SP were rich in essential and umami amino acids, and all three fractions had high arginine contents. The essential amino acid index and predicted biological value of WF were 75.84 and 90.96, respectively. These values were considerably higher than those of MP and SP. Meanwhile, the predicted protein efficiency ratio of MP was the highest. Lysine was the first limiting essential amino acid (EAA) in MP and SP, and the score of the first limiting EAA (tryptophan) in WF was more than 100%. The in vitro protein digestibility of WF and SP was approximately 92% higher than that of MP. The in vivo experiments showed that WF was the easiest to digest. The nutritional value and high digestibility of WF can be claimed as a high-quality protein source based on the current findings., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

We report the first preparation of a monoclonal antibody (mAb) that can immobilize a palladium (Pd)-complex. The allylic amination reaction using a supramolecular catalyst consisting of the Pd-complex and mAb selectively gives the (R)-enantiomer product with an enantiomeric excess (ee) of 98 ± 2%. This is in sharp contrast to the reaction catalyzed by a conventional Pd-catalyst (ee < 2%).

The formation of the mollusk shell requires the participation of proteins, many of which may be interactive with one another. We examined a model protein pair system from the mollusk Haliotis rufescens , wherein we probed the interactions between recombinant forms of two major nacre layer proteins, AP7, and the glycoprotein, AP24. Here, the focus was on the impact that the AP24 glycosylation and primary sequence had on AP24-AP7 binding. We find that both the glycosylated and nonglycosylated variants of AP24 bound to AP7 but with different quantities, kinetics, and internal rearrangements. Moreover, the binding of AP7 with nonglycosylated and glycosylated AP24 was found to be Ca(II)-dependent and -independent, respectively. Yet both variants of AP24 combine with AP7 to form hybrid hydrogel particles that are similar in their physical properties. Thus, AP7 and AP24 protein sequences are interactive and form hydrogels, but the interactions are tuned by glycosylation and Ca(II). These features may have an impact on the nacre matrix formation.

The purpose of this paper is to investigate the trace metal content in edible biomonitors (i.e., mollusks) in the Beagle Channel (southern Patagonia) and to assess the human health risks associated with their consumption. Rationale: The monitoring breakdown structure (MBS) conceptual model was applied to four sampling campaigns (2005 → 2012) that collected 729 samples of Mytilus chilensis and Nacella magellanica. The composition of trace elements (Cd, Cr, Cu, Ni, Pb and Zn) in the mollusks was determined using graphite furnace (GFAAS) or flame atomic absorption spectrometry (FAAS). We compared the mean obtained values with the maximum levels (MLs) of each element established by international organizations. Then, based on semi-structured interviews, we calculated the estimated daily intake (EDI) of local residents and compared it with safety reference doses, i.e., the provisional tolerable daily intake (PTDI), provisional maximum tolerable daily intake (PMTDI), and tolerable daily intake (TDI), as well as the benchmark dose level lower confidence limit for Pb (BMDL 01 , a reference point (RP)/point of departure (POD). Moreover, to obtain information about the potential health risks of ingesting heavy metals (HMs) through mollusk consumption, we evaluated the target hazard quotient (THQ) and the hazard index (HI). Findings: For Cd and Pb, 65% and 40% of bivalves exceeded the MLs established by the Mercado Común del Sur (Mercosur), respectively. Except for Cd in N. magellanica (i.e., 1.20 μg/kg/bw/day), EDI values were clearly lower than the safety reference doses. For Cr, Cu, Ni, Pb and Zn, mussels were safe for consumption and did not raise concerns for public health. Likewise, THQ values were well below one for most of the studied metals, indicating that the exposed human population is assumed to be safe. Occasional high consumers of mollusks from the most contaminated sites may be at some health risk. Originality: The food production system and the environment are complex systems; this is crucial to understand when we consider ecosystems as a food source (i.e., marine ecosystems). Here we consider edible biomonitors, that are organisms that can have a dual function. They are food, and at the same time, if properly calibrated, they can act as indicators of environmental quality. This study is the first to investigate relevant essential and non-essential trace metal content in two edible mollusks from the Beagle Channel in a long-term survey (2005 → 2012). The information variety was high; approximately thirteen thousand determinations were conducted to support the risk assessment for mollusk consumption. Other aspects connected with the health risks and the uncertainty factors related to the presence of essential and non-essential minerals in edible mollusks as well as the use of the MBS are also discussed., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Information on the occurrence and trophodynamics of per- and polyfluoroalkyl substances (PFASs) in the Antarctic region is limited. We investigated the occurrence of PFASs in an ecosystem in the Fildes Peninsula at King George Island and Ardley Island, Antarctica. The profiles, spatial distribution, and trophic transfer behavior of PFASs were further studied. ∑PFASs ranged from 0.50 ± 38.0 ng/g dw (dry weight) in algae to 4.97 ± 1.17 ng/g dw in Neogastropoda (Ngas), which was lower than those in the low- and mid-latitude regions and even Arctic regions. Perfluorobutyric acid (PFBA) was predominant with detection frequencies above 50% in all types of samples, and the relative contribution of PFBA ranged from 22% to 57% in the biota samples. The biomagnification factors of PFBA, perfluoroheptanoate (PFHpA), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) between Archaeogastropoda (Agas) and Ngas were 0.67 ± 0.54, 0.77 ± 0.38, 1.04 ± 1.56, 3.30 ± 4.07, and 1.61 ± 0.89, respectively. The trophic magnification factors of PFHxS and PFOS were 2.09 and 2.92, respectively, which indicated that they could be biomagnified through the food chain. Considering the increasing production and uncertain toxicological risks of emerging PFASs and the sensitive ecosystems in Antarctic regions, more attention should be paid, especially for the short-chain ones in the Antarctic region., (Copyright © 2019 Elsevier Ltd. All rights reserved.)