Marine Molluscs Research Articles

Species identification, reproductive biology, and nutritional value of marine shellfish (Meretrix lyrata) in the Bay of Bengal

Meretrix lyrata which is under the family of Veneridae and under the order of Venerida, is a nutritionally and economically important edible mussel in Bangladesh. However, studies on species identification and nutritional value in M. lyrata are scarce. Therefore, a detailed investigation was conducted on (i) species identification of the common edible mussel through DNA-barcoding and morphometrics, (ii) reproductive features, such as size at sexual maturity, spawning, and peak-spawning seasons under different environmental factors, and (iii) nutritional status through proximate analysis of M. lyrata mussel collected from the Bay of Bengal, Bangladesh. The results indicated that the size at sexual maturity for M. lyrata was 4.2 cm and the spawning seasons were significantly affected by the dissolve oxygen and salinity. The study also demonstrated that the spawning of M. lyrata occurred from January to June and December while peak spawning season was May in the Bay of Bengal. The higher protein and moisture contents with lower fat in M. lyrata indicated that are value-added seafood with higher nutritional values for consumers.

Replacing mechanical protection with colorful faces-twice: parallel evolution of the non-operculate marine worm-snail genera Thylacodes (Guettard, 1770) and Cayo n. gen. (Gastropoda: Vermetidae).

Vermetid worm-snails are sessile and irregularly coiled marine mollusks common in warmer nearshore and coral reef environments that are subject to high predation pressures by fish. Often cryptic, some have evolved sturdy shells or long columellar muscles allowing quick withdrawal into better protected parts of the shell tube, and most have variously developed opercula that protect and seal the shell aperture trapdoor-like. Members of Thylacodes (previously: Serpulorbis) lack such opercular protection. Its species often show polychromatic head-foot coloration, and some have aposematic coloration likely directed at fish predators. A new polychromatic species, Thylacodes bermudensis n. sp., is described from Bermuda and compared morphologically and by DNA barcode markers to the likewise polychromatic western Atlantic species T. decussatus (Gmelin, 1791). Operculum loss, previously assumed to be an autapomorphy of Thylacodes, is shown to have occurred convergently in a second clade of the family, for which a new genus Cayo n. gen. and four new western Atlantic species are introduced: C. margarita n. sp. (type species; with type locality in the Florida Keys), C. galbinus n. sp., C. refulgens n. sp., and C. brunneimaculatus n. sp. (the last three with type locality in the Belizean reef) (all new taxa authored by Bieler, Collins, Golding & Rawlings). Cayo n. gen. differs from Thylacodes in morphology (e.g., a protoconch that is wider than tall), behavior (including deep shell entrenchment into the substratum), reproductive biology (fewer egg capsules and eggs per female; an obliquely attached egg capsule stalk), and in some species, a luminous, "neon-like", head-foot coloration. Comparative investigation of the eusperm and parasperm ultrastructure also revealed differences, with a laterally flattened eusperm acrosome observed in two species of Cayo n. gen. and a spiral keel on the eusperm nucleus in one, the latter feature currently unique within the family. A molecular phylogenetic analysis based on mitochondrial and nuclear rRNA gene sequences (12SrRNA, trnV, 16SrRNA, 28SrRNA) strongly supports the independent evolution of the two non-operculate lineages of vermetids. Thylacodes forms a sister grouping to a clade comprising Petaloconchus, Eualetes, and Cupolaconcha, whereas Cayo n. gen is strongly allied with the small-operculate species Vermetus triquetrus and V. bieleri. COI barcode markers provide support for the species-level status of the new taxa. Aspects of predator avoidance/deterrence are discussed for these non-operculate vermetids, which appear to involve warning coloration, aggressive behavior when approached by fish, and deployment of mucous feeding nets that have been shown, for one vermetid in a prior study, to contain bioactive metabolites avoided by fish. As such, non-operculate vermetids show characteristics similar to nudibranch slugs for which the evolution of warning coloration and chemical defenses has been explored previously.

First report of the genus Thorectichthys (Ellimmichthyiformes) in America, from the Cenomanian deposits of the Cintalapa Formation, Chiapas, southeastern Mexico

The El Chango quarry is an outstanding paleontological site of Mexico. The marine limestones of this site represent a small outcrop of the Cintalapa Formation and bear a significant assemblage of Early Cenomanian continental plants plus marine crustaceans, decapods, mollusks, and fishes. This paper includes the description of a double-armored herring species from El Chango, which is named Thorectichthys fideli and belongs to the family Paraclupeidae, in the order Ellimmichthyiformes. This new species shares the diagnostic generic features with T. marocensis and T. rhadinus, two slightly younger North African species previously discovered in Cenomanian–Turonian deposits of the Akrabou Formation, Morocco. The new species has a couple of peculiar features never before observed in the ellimmichthyiforms; the caudal skeleton of this fish has four uroneurals, and the horizontal limb of the preopercle is dorsally notched allowing the superficial lateral exposure of a broad and massive posterior process of the quadrate. Including this species in a comprehensive phylogenetic analysis confirms the monophyletic nature of Thorectichthys and its inclusion as a basal clade of the family Paraclupeidae. Thorectichthys fideli sp. nov. adds to an increasing assemblage of Mexican Cretaceous ellimmichthyiforms that includes ancestral as well as more derivatives species that shows the broad Albian–Cenomanian distribution of the ellimmichthyiforms, along the epicontinental environments of the Tethys Sea.

ChIP-seq identifies McSLC35E2 as a novel target gene of McNrf2 in Mytilus coruscus, highlighting its role in the regulation of oxidative stress response in marine mollusks.

NF-E2-related factor 2 (Nrf2) plays a crucial role in the oxidative regulatory process, which could trigger hundreds of antioxidant elements to confront xenobiotics. In the previous study, we identified Nrf2 from the marine mussel Mytilus coruscus, and the findings demonstrated that McNrf2 effectively protected the mussels against oxidative stress induced by benzopyrene (Bap). In order to delve deeper into the underlying mechanism, we utilized Chromatin Immunoprecipitation followed by sequencing (ChIP-seq) technology to systematically identify potential novel target genes of McNrf2. A total of 3,465 potential target genes were screened, of which 219 owned binding sites located within the promoter region. During subsequent experimental verification, it was found that McSLC35E2, a candidate target gene of McNrf2, exhibited negative regulation by McNrf2, as confirmed through dual luciferase and qRT-PCR detection. Further, the enzyme activity tests demonstrated that McNrf2 could counteract Bap induced oxidative stress by inhibiting McSLC35E2. The current study provides valuable insights into the application of ChIP-seq technology in the research of marine mollusks, advancing our understanding of the key role of Nrf2 in antioxidant defense mechanisms, and highlighting the significance of SLC35E2 in the highly sophisticated regulation of oxidative stress response in marine invertebrates.

From reproductive behaviour to responses to predators: Ocean acidification does not impact the behaviour of an herbivorous marine gastropod

Ocean acidification (OA), which reduces ocean pH and leads to substantial changes in seawater carbonate chemistry, may strongly impact organisms, especially those with carbonate skeletons. In marine molluscs, while the physiological effects of OA are well known, with a reduction of growth and shell calcification, there are few studies on behavioural effects. A large marine gastropod, Haliotis tuberculata, was exposed to ambient (pHT 8.0) or low pH (pHT 7.7) during a 5-month experiment. Because animal fitness can be affected through various behavioural changes, a broad spectrum of behavioural parameters was investigated, including situations involving no stress, responses to predators, righting to evaluate indirectly the level of energy reserves, and finally, reproductive behaviour. In addition, we measured the expression profile of the GABA A-like and serotonin receptor genes, often described as central neuromodulators of sensory performance and behaviour and known to be affected by OA in molluscs. No significant effect of low pH as compared to ambient pH was observed on abalone behaviour for any of these behavioural traits or gene expressions after either one week or several months of exposure to OA. The significance tests were corroborated by estimating the size of pH effects. The behaviour of this mollusc appears not to be affected by pH decrease expected by the end of the century, suggesting some resilience of the species to OA at the adult stage. This is probably related to the ecological niche of this abalone, where important pH variations can be observed at tidal, diurnal or seasonal scales.

Effects of Three Microalgal Diets Varying in LC-PUFA Composition on Growth, Fad, and Elovl Expressions, and Fatty Acid Profiles in Juvenile Razor Clam Sinonovacula constricta

The razor clam Sinonovacula constricta is the first marine mollusk demonstrated to possess the complete long-chain polyunsaturated fatty acids (LC-PUFA) biosynthetic pathway. This study explored the impact of different microalgae on growth, Fad and Elovl expressions, and fatty acid (FA) profiles in juvenile S. constricta. Results revealed that juveniles fed with Isochrysis galbana (rich in DHA) or Chaetoceros calcitrans (rich in EPA) consistently exhibited higher growth than those fed Chlorella sp. (rich in LA and ALA), underscoring the importance of dietary LC-PUFA in S. constricta’s development. Expression of most Fad and Elovl in C. calcitrans and I. galbana-fed juveniles were initially up-regulated, then down-regulated, suggesting LC-PUFA demand for faster growth. Although Chlorella sp.-fed juveniles exhibited decreased mRNA levels for most genes, levels were notably higher lately compared to those fed C. calcitrans or I. galbana, hinting at potential LC-PUFA biosynthesis induction. FA profiles in S. constricta generally mirrored those in ingested microalgae, implying direct FA accumulation from diets. Some microalgal FA were absent in farmed S. constricta, while others emerged, indicating S. constricta’s ability to selectively accumulate and synthesize FA. This study enhances the understanding of dietary FA metabolism in S. constricta, valuable for selecting appropriate microalgae in its farming practices.

Shell Tools and Use-Wear Analysis: a Reference Collection for Prehistoric Arabia

Prehistoric and Archaeological research has pointed out the role of marine resources in modern humans’ cognitive and cultural developments. Maritime adaptations constitute a key component of the sociocultural evolution in Eastern Arabia. During the Neolithic (c. 6500–3300 BCE), it is expressed by the colonisation of offshore islands supported by advanced seafaring and the exploitation of marine resources not only for staple food but also for obtaining hard animal materials used for both symbolic and technological productions, respectively in the form of personal adornments and tooling. Although tools made of retouched large marine mollusc shells are reported on several sites, no detailed study has been conducted on their function and role within the socio-technological processes.The present study introduces a prospective approach for the functional analysis of archaeological shell tools from Eastern Arabia. A reference collection of use-wear traces made experimentally has been built: it compiles the results of 65 experiments (23 are documented and illustrated in the present study), including the processing of various animal, vegetal, and mineral materials. Use-wear traces have been observed and described using both low and high-power magnifications (conducted mainly at 100 ×). It provides helpful methodological support for future comparisons with archaeological specimens. The procurement conditions of the shell valves and the techniques of retouch have been discussed in detail, allowing further considerations on the degree of the socio-technological investment devoted to these peculiar artefacts.

Expanded Polystyrene-Debris-Induced Genotoxic Effect in Littoral Organisms.

Expanded polystyrene (EPS) is a major component of plastic debris in the environment, including coastal and littoral zones. EPS is widely used in various industries including fish farming and aquaculture, which poses a serious potential threat not only to cultured hydrobionts but also to all living organisms, including humans. This paper presents the results of experimental studies on the effects of EPS (0.024 m2/L) on marine mollusks Mytilus trossulus and Tegula rustica, which are typical inhabitants of the upper littoral of Peter the Great Bay (Sea of Japan), belonging to different systematic groups and differing in the type of nutrition. The results of biochemical marker analysis showed the development of oxidative stress processes. Thus, increasing malondialdehyde content relative to control values was registered in the digestive glands of M. trossulus and T. rustica. In the cells of the digestive glands of M. trossulus, integral antioxidant activity decreased more than 1.5 times compared with that of the control. The change in the concentration of protein carbonyls was unchanged in M. trossulus, whereas in T. rustica, there was a 1.5-fold increase. EPS exposure also resulted in significant DNA damage in the studied mollusks-the damage level increased 2.5-fold in M. trossulus and 1.5-fold in T. rustica relative to the control, indicating the genotoxic potential of EPS litters.

Marine mollusk biodiversity in Northeastern islands of Vietnam, impact factors and proposing conservation solutions

A biodiversity and water-quality monitoring campaign was conducted in the Northeastern archipelago of Vietnam, including Quang Ninh province and Hai Phong, in 2017–2018. Mollusks are selected as the critical proxy indicator, and water-quality parameters are tested against National acceptability standards. The study revealed that, despite declining trends over the past two decades, mollusks are still highly diverse, with 647 species belonging to 227 genera, 95 families, and five classes (76% of all the species identified in the Tonkin Gulf). Of these, 253 species of 39 families (39% of the whole stock) are of high economic value, supporting an active trade in the region and thousands of livelihoods. Several species (abalone, blood cockle, green mussel, pearl oysters, Pacific oysters, double-headed clams, Asian hard clams, white clams, and squids) are intensively farmed. However, aquaculture still needs to be derdeveloped as capture from the wild is preferred. Water quality is unexpectedly high despite impacting factors such as urban development, industry, mass tourism, and demographic increase, mainly within the limits of acceptability set by the Government. Salinity, pH, and temperature are compatible with marine life, and a limited impact is represented by dissolved nitrates and suspended hydrocarbons in suspension. Despite favorable conditions of the aquatic environment, biodiversity decline has been a steady trend over the past decade. The causes are the urban encroachment over the coastal tract, the intertidal spawning grounds, breeding grounds, and nurseries, overexploitation, IUU fishing, lack of management, and failed establishment of conservation areas and MPAs. Spawning and breeding grounds identification and demarcation, their participated co-management, investments in environmental protection, technologies, and capacity building, and promotion of aquafarming of marketable species are among the measures recommended to be implemented with priority, to relieve the pressure over the wild stock and promote regeneration. The role of science in monitoring and detecting environmental changes guiding the adoption of proactive measures to prevent depletion and stock collapse, is the pathway to the sustainability of resource use and human well-being.

Hyperglycemia effect of Pinctada martensii hydrolysate in diabetic db/db mice

Ethnopharmacological relevancePinctada martensii (Dunker) and other marine shellfish flesh have been traditionally used in China as folk remedies regulate blood sugar. Aim of the studyTo investigate the main active constituents and the pharmacological mechanism of Pinctada martensii flesh enzymatic hydrolysate (PMH) against T2DM. Materials and methodsThe hypoglycemic activity of enzymolysis peptides from Pinctada martensii was evaluated by using db/db mice, through the influence of glycemic index, blood lipid and key protein expression of PI3K-Akt pathway. In addition, label-free quantitative proteomics was used to screen the key proteins for Pinctada martensii hydrolysate (PMH) to improve T2DM, and Western blot and qRT-PCR were used to verify the expression difference of differential proteins at protein and mRNA levels between different groups. ResultsPMH were prepared and characterized. In vivo investigations revealed that the PMH could regulate blood glucose and improve glucose tolerance and insulin tolerance, reduced serum total cholesterol, triglyceride, low-density lipoprotein cholesterol levels and increase high-density lipoprotein cholesterol levels in db/db mice. Western blot results showed that PMH could up-regulate IRS-1, P-PI3K/PI3K and P-Akt/Akt levels in db/db mice. Label-free quantitative proteomic approach was used to analyze the proteome in db/db mouse liver, 231 proteins were reversed significantly (p < 0.05), and these proteins were involved in oxidative phosphorylation, glycolysis/gluconeogenesis and other pathways. Further screened 15 proteins with FC > 1.2 could be enriched in the retinol metabolic pathway, and the proteins in this pathway were also verified. ConclusionsPMH has hypoglycemic effect and can be used as a potential natural T2DM intervener. The hypoglycemic activity of PMH is related to its regulation of the PI3K/AKT pathway. The PI3K/AKT pathway and the retinol pathway are considered as another potential pathway for PMH to exert hypoglycemic effects.

Micromollusk families in 2 contrasting seasons in Bahia de los Angeles, Gulf of California, Mexico

Marine mollusks provide important ecosystem services. They create habitats for benthic organisms, filter water, biodeposit organic carbon in the seafloor, and serve as food sources for other organisms. Studies of mollusk diversity require time-consuming methods to process samples and identify species. Thus, it is not surprising that most studies have focused on macromollusks that can be collected and processed easily, ignoring micromollusk species. Without understanding the ecology and distributions of micromollusks properly, it is impossible to assess their populations and implement adequate conservation measures. Here we present microgastropods collected in Bahia de los Angeles at the family level for September 2013 (summer) and February 2014 (winter). During each season, we sampled 6 coastal sediment stations, and analyzed depth, salinity, temperature, granulometry, and organic matter. A total of 20,353 specimens were collected: 15,310 in summer and 5,043 in winter. Seven micromollusk families were identified: Barleeidae, Caecidae, Cerithiidae, Eulimidae, Pyramidellidae, Rissoidae, and Tornidae. Caecidae and Barleeidae exhibited the highest densities among all families in summer and winter, respectively (278,044 ind·m–2, 142,222 ind·m–2). The lowest densities for summer and winter were observed for the Tornidae family (~1,867 ind·m–2, ~1,411 ind·m–2). Barleeidae, Caecidae, Cerithiidae, Rissoidae, and Tornidae were classified as herbivorous and detritivorous; Eulimidae and Pyramidellidae, as carnivorous and ectoparasitic. Tornidae and Eulimidae showed symbiotic relationships with various invertebrate species. The Bayesian analysis of variance indicated a high probability of differences only in summer (BF &gt; 3). When comparing the stations in both periods, all stations, except station 6, showed differences between periods (BF &gt; 3). The canonical correlation analysis indicated some associations between family abundances and temperature. This study provides valuable information that expands the knowledge of micromollusk biodiversity in the coastal area of Bahia de los Angeles, an important site for conservation in Mexico.

The Hālawa dune site, Moloka‘i, Hawaiian Islands: New excavations, redating, and new interpretations

The Hālawa dune site on Moloka‘i Island has played a key role in understanding early Hawaiian history. Initially excavated in 1969–1970 and regarded then as dating to the early phase of Hawaiian settlement, the site yielded a diverse artifact assemblage and the first evidence for round-ended house foundations in Hawai‘i. Prior attempts to refine the site’s chronology yielded inconsistent results. Renewed excavations and re-analysis of previously excavated collections from the site have allowed for recovery of a stratigraphically controlled sample of faunal materials and charcoal. AMS dating of candlenut endocarp indicates initial use of Mound A cal AD 1366–1610, with occupation continuing into the post-contact period. Matched pairs of candlenut and marine mollusk shell dates allow for the derivation of a Hālawa-specific marine reservoir value (ΔR = −267), in turn permitting the calibration of 12 dates on marine mollusk shells excavated from Mound B in 1970. Faunal materials from the 2020 Mound A excavation add new information on patterns of marine exploitation, and on a trend of increased frequency of domestic pig and dog over time. Charcoal identified from Mound A indicates largely native forest taxa, but with several Polynesian-introduced plants as well, including candlenut, breadfruit, and mountain apple.

Ecological benefits of artificial light at night (ALAN): Accelerating the development and metamorphosis of marine shellfish larvae

Urbanization has led to increasing use of artificial light at night (ALAN), which has rapidly become an important source of pollution in many cities. To identify the ALAN effects on the embryonic development of the Pacific abalone Haliotis discus hannai, we first exposed larvae to natural light with a light period of 12 L:12D (control, Group CTR). We then exposed larvae to three different light regimes. Larvae in Group NL were exposed to full spectrum artificial light from 18:00 to 00:00 to simulate the lighting condition at night, whereas Groups BL and YL were illuminated at the same time interval with 450 nm of short-wavelength blue light and 560 nm of long-wavelength orange light, respectively, to simulate billboard lighting at night. There were significantly higher hatching success and metamorphosis rates of larvae in Group BL than in Group YL or CTR (P < 0.05). The larvae in Group YL had the highest abnormality rate and took the longest time to complete metamorphosis. Transcriptomic studies revealed significantly higher expression levels of genes related to RNA transport, DNA replication, and protein processing in endoplasmic reticulum pathways in Group BL compared to the other groups. In the metabolomic analysis, we identified prostaglandin B1, tyramine, d-fructose 6-phosphate, L-adrenaline, leukotriene C4, and arachidonic acid as differential metabolic markers, as they play a vital part in helping larvae adapt to different ALAN conditions. Multi-omics correlation analysis of pairwise comparisons between all of the groups suggested that the biosynthesis of unsaturated fatty acids (FAs) and arachidonic acid metabolism pathways were significantly enriched (P < 0.05). Further quantitative analysis of the fatty acid (FA) contents revealed that 42 out of 50 FAs were down-regulated in Group BL and up-regulated in Group YL, which suggested that the synthesis, catabolism, and metabolism of FAs are crucial for the larval response to different spectral components of ALAN. For the first time, we report positive rather than negative effects of artificial blue light at night on the embryonic development of a benthic marine species. These results are significant for unbiased and full-scale assessment of the ecological effects of ALAN and for understanding the structural stability of the marine benthic community.

Effects of Marine Shellfish on Mechanical Properties and Microstructure of Coral Concrete

Using coral debris as coarse and fine aggregates and seawater as mixing water has been proposed to address transportation and material shortage issues in island and reef construction projects. However, the utilization of coral may result in impurities, such as shellfish and other marine organisms, which could impact the mechanical properties of the resulting concrete. The goal of this study is to find out how different amounts of shellfish and marine organism impurities affect the mechanical properties and microstructure of coral concrete. This study builds on the process of making full coral concrete. Substitution optimization is carried out using the response surface method (RSM), with the polynomial work expectation serving as a validation measure. The experimental findings indicate that impurities have an insignificant impact on the mechanical properties of coral concrete when their dosage is below 2%, causing a decrease of only around 6%. The mechanical properties of coral concrete containing shellfish and marine organism impurities exhibit a strong correlation at 28 days. SEM and XRD analysis revealed that the primary factor contributing to the decline of mechanical properties in coral concrete with shellfish and marine organism impurities is the weak strength of the impurity shell structure, in addition to the rehydration of internal biomass during the cement hydration process, leading to the formation of numerous small pores within the coral concrete. The results of an ANOVA test indicate that the model is statistically significant, with a p-value of less than 0.05.

Extensive woodland pasturing supported Pitted Ware Complex livestock management systems: Multi-stable isotope evidence from a Neolithic interaction zone

Middle Neolithic Pitted Ware Complex (PWC) groups throughout the Baltic coastal areas of Scandinavia almost exclusively exploited marine resources for their subsistence. However, Pitted Ware communities inhabiting eastern Jutland (Denmark) also heavily relied on domesticated livestock, reflecting their close contacts and interactions with neighboring Funnel Beaker agriculturalists. Whether or not these domesticates were managed using husbandry practices designed to intensively enhance livestock production or herded using more extensive management strategies that may have better articulated with seal hunting, shellfish gathering, and fishing activities remains unknown. Here, multi-stable isotopic analyses conducted on bone collagen and enamel apatite from wild and domesticated animal species recovered from Pitted Ware sites in Djursland indicate that hunters regularly sought prey that roamed in deeply canopied forests but extensively pastured their livestock under lightly canopied woodlands while also grazing some animals in more open habitats at moderately high stocking rates. Cattle may have been grazed on crop stubble after the summer harvest but were not fed grassy hay or agricultural by-products during the winter season. Instead, they were provided with leaf fodder sourced from diverse woodland pastures. The use of extensive pasturing regimes for livestock by PWC groups fitted well with the intensive exploitation of marine mammals, fishes, and shellfish as part of a highly resilient, sustainable subsistence complex.

Selection of the Best Solvent Extract for Antimicrobial Activity Obtained from Marine Mollusca Shells

Marine organisms are a rich source of structurally novel and biologically active metabolites. So far, many chemically unique compounds of marine origin with different biologically activity have been isolated and a number of them are under investigation and/or are being developed as new pharmaceuticals. Screening of secondary metabolites from Mollusca shell is a common approach to identify compounds of biomedical importance. The aim of the present study is to assessment of antimicrobial activity of different extracts from ten different (Anadara antiquata, Anadara rhombea, Chicoreus virgineus, Donax cuneatus, Mactra violacea, Pugilina cochlidium, Donax scortum, Turritella acutangula, Trachycardium asciaticum and Tonna dolium) Mollusca s shell. The shell powders were immersed separately in ethanol, acetone, methanol and cold steeped for overnight at -18°C. The antimicrobial effects of different (Ethanol, acetone and methanol) extracts were tested against Escherichia coli and Candida albicans strains. The extract obtained from ethanol showed a higher degree of inhibition to the both microbes. Maximum zone of inhibition was exhibited P. cochlidium against E. coli (7.00mm) and C. albicans (5.40mm) by the ethanol extract as compared to other extracts. On the basis of antimicrobial activity of different extracts, ethanol extract is used for further subsequent antimicrobial activities.

Transcriptome and digital gene expression analysis reveal immune responses of mantle and visceral mass pearl culturing in Hyriopsis cumingii

Biomineralization is a widespread phenomenon in marine mollusks and is responsible for the production of shells and pearls. However, the regulatory mechanisms governing the adaptive immune responses in the mollusk mantle and visceral mass during mineralization remain unclear. In this work, we examined the mantle and visceral mass immune responses of Hyriopsis cumingii during pearl culture using high-throughput sequencing techniques. A mantle transcriptome database was established using transcriptome sequencing technology and reference to the major databases. Digital gene expression profiling was used to identify the differentially expressed genes of mantle and visceral mass at different insertion periods. Moreover, quantitative real-time PCR was used to verify the expression of five immune-related genes. Transcriptome sequencing results showed 257,457 unigenes were identified. Digital gene expression profiles showed 1389, 3572, 1888, and 2613 differentially expressed genes (DEGs) in the mantle and visceral mass at 5, 20, 50, and 90 d after insertion, respectively, with the highest number at 20 d and the lowest at 5 d after insertion (q &amp;lt; 0.05). A cluster analysis of the DEGs showed similar clustering and expression features in the mantle to the control group, and at 5, 50 and 90 d, after mantle insertion. The DEGs in the visceral mass showed similar clustering and expression features to the control group and at 5, 20 and 50 d after insertion. We also screened 22 immune-related DEGs in the mantle and visceral mass during the same pearl culture period, including serine/threonine-protein kinase NLK, C-type lectin, and galectin. The greatest number of DEGs was found 90 d after insertion. Compared with the mantle, more immune-related DEGs were down-regulated than up-regulated in the visceral mass during pearl culture, indicating that the immune regulatory mechanisms in the visceral mass and the mantle differ during pearl culture, and that the visceral mass is liable to higher infection and mortality rates. Quantitative real-time PCR results showed that the expression of five immune-related genes was consistent with DGE results. Our findings will further knowledge of the immune systems that are present in the mantle and visceral mass during pearl culture.

Marine-Derived Components: Can They Be a Potential Therapeutic Approach to Parkinson's Disease?

The increase in the life expectancy average has led to a growing elderly population, thus leading to a prevalence of neurodegenerative disorders, such as Parkinson's disease (PD). PD is the second most common neurodegenerative disorder and is characterized by a progressive degeneration of the dopaminergic neurons in the substantia nigra pars compacta (SNpc). The marine environment has proven to be a source of unique and diverse chemical structures with great therapeutic potential to be used in the treatment of several pathologies, including neurodegenerative impairments. This review is focused on compounds isolated from marine organisms with neuroprotective activities on in vitro and in vivo models based on their chemical structures, taxonomy, neuroprotective effects, and their possible mechanism of action in PD. About 60 compounds isolated from marine bacteria, fungi, mollusk, sea cucumber, seaweed, soft coral, sponge, and starfish with neuroprotective potential on PD therapy are reported. Peptides, alkaloids, quinones, terpenes, polysaccharides, polyphenols, lipids, pigments, and mycotoxins were isolated from those marine organisms. They can act in several PD hallmarks, reducing oxidative stress, preventing mitochondrial dysfunction, α-synuclein aggregation, and blocking inflammatory pathways through the inhibition translocation of NF-kB factor, reduction of human tumor necrosis factor α (TNF-α), and interleukin-6 (IL-6). This review gathers the marine natural products that have shown pharmacological activities acting on targets belonging to different intracellular signaling pathways related to PD development, which should be considered for future pre-clinical studies.

A bone morphogenetic protein regulates the shell formation of Crassostrea gigas under ocean acidification

Bone morphogenetic proteins (BMPs) are key factors controlling osteoblast differentiation, which have been proved to be involved in the hard tissue formation of marine mollusks. In the present study, a member of BMPs gene (CgBMP7) was identified from Pacific oyster Crassostrea gigas (C. gigas) with the aim to understand its possible role in the regulation of shell formation under ocean acidification (OA) conditions. The open reading frame (ORF) of CgBMP7 was of 1254 bp encoding a polypeptide of 417 amino acids. The deduced amino acid sequence of CgBMP7 was comprised of one signal peptide, one prodomain and one TGF-β domain, which shared 21.69%-61.10% identities with those from other species. The mRNA transcript of CgBMP7 was ubiquitously expressed in all the tested tissues of adult oysters with a higher expression level in mantle, notably highest in the middle fold (MF) of the three folds of mantle. The expression level of bone morphogenetic protein type I receptor (CgBMPR1B) mRNA was also highest in the MF and up-regulated dramatically post recombinant BMP7 protein (rCgBMP7) stimulation. After the blockage of BMPR1B with inhibitor LDN193189 (LDN), the mRNA expression level and phosphorylation level of CgSmad1/5/8 in mantle were decreased, and the mRNA expression levels of CgCaM and Cgengrailed-1 were down-regulated significantly. During the oysters were exposed to acidified seawater for weeks, the expression levels of CgBMP7, CgBMPR1B and CgSmad1/5/8 in the MF decreased significantly (p < 0.01) at the 4th week, and CgCaM and Cgengrailed-1 also exhibited the same variable expression patterns as CgBMP7. In addition, the growth of shell in the treatment group (pH 7.8) was slower than that in the control group (pH 8.1). These results collectively indicated that BMP7 was able to trigger the BMPR-Smad signaling pathway and involved in controlling the formation of oyster calcified shell under OA conditions.

Ballistic Behavior of Bioinspired Nacre-like Composites.

In this paper, the ballistic performance of a multilayered composite inspired by the structural characteristics of nacre is numerically investigated using finite element (FE) simulations. Nacre is a natural composite material found in the shells of some marine mollusks, which has remarkable toughness due to its hierarchical layered structure. The bioinspired nacre-like composites investigated here were made of five wavy aluminum alloy 7075-T651 (AA7075) layers composed of ~1.1-mm thick square tablets bonded together with toughened epoxy resin. Two composite configurations with continuous layers (either wavy or flat) were also studied. The ballistic performance of the composite plates was compared to that of a bulk monolithic AA7075 plate. The ballistic impact was simulated in the 300-600 m/s range using two types of spherical projectiles, i.e., rigid and elastoplastic. The results showed that the nacre plate exhibited improved ballistic performance compared to the bulk plate and the plates with continuous layers. The structural design of the nacre plate improved the ballistic performance by producing a more ductile failure and enabling localized energy absorption via the plastic deformation of the tablets and the globalized energy dissipation due to interface debonding and friction. All the plate configurations exhibited a better ballistic performance when impacted by an elastoplastic projectile compared to a rigid one, which is explained by the projectile plastic deformation absorbing some of the impact energy and the enlarged contact area between the projectile and the plates producing more energy absorption by the plates.