Biomineral crystallographic preferred orientation in Solenogastres molluscs (Aplacophora) is controlled by organic templating.

Aplacophoran molluscs are shell-less and have a worm-like body which is covered by biomineralized sclerites. We investigated sclerite crystallography and the sclerite mosaic of the Solenogastres species Dorymenia sarsii, Anamenia gorgonophila, and Simrothiella margaritacea with electron-backscattered-diffraction (EBSD), laser-confocal-microscopy and FE-SEM imaging. The soft tissue of the molluscs is covered by spicule-shaped, aragonitic sclerites. These are sub-parallel to the soft body of the organism. We find, for all three species, that individual sclerites are untwinned aragonite single crystals. For individual sclerites, aragonite c-axis is parallel to the morphological, long axis of the sclerite. Aragonite a- and b-axes are perpendicular to sclerite aragonite c-axis. For the scleritomes of the investigated species we find different sclerite and aragonite crystal arrangement patterns. For the A. gorgonophila scleritome, sclerite assembly is disordered such that sclerites with their morphological, long axis (always the aragonite c-axis) are pointing in many different directions, being, more or less, tangential to cuticle surface. For D. sarsii, the sclerite axes (equal to aragonite c-axes) show a stronger tendency to parallel arrangement, while for S. margaritacea, sclerite and aragonite organization is strongly structured into sequential rows of orthogonally alternating sclerite directions. The different arrangements are well reflected in the structured orientational distributions of aragonite a-, b-, c-axes across the EBSD-mapped parts of the scleritomes. We discuss that morphological and crystallographic preferred orientation (texture) is not generated by competitive growth selection (the crystals are not in contact), but is determined by templating on organic matter of the sclerite-secreting epithelial cells and associated papillae.

Advancing responsible genomic analyses of ancient mollusc shells.

The analysis of the DNA entrapped in ancient shells of molluscs has the potential to shed light on the evolution and ecology of this very diverse phylum. Ancient genomics could help reconstruct the responses of molluscs to past climate change, pollution, and human subsistence practices at unprecedented temporal resolutions. Applications are however still in their infancy, partly due to our limited knowledge of DNA preservation in calcium carbonate shells and the need for optimized methods for responsible genomic data generation. To improve ancient shell genomic analyses, we applied high-throughput DNA sequencing to 27 Mytilus mussel shells dated to ~111-6500 years Before Present, and investigated the impact, on DNA recovery, of shell imaging, DNA extraction protocols and shell sub-sampling strategies. First, we detected no quantitative or qualitative deleterious effect of micro-computed tomography for recording shell 3D morphological information prior to sub-sampling. Then, we showed that double-digestion and bleach treatment of shell powder prior to silica-based DNA extraction improves shell DNA recovery, also suggesting that DNA is protected in preservation niches within ancient shells. Finally, all layers that compose Mytilus shells, i.e., the nacreous (aragonite) and prismatic (calcite) carbonate layers, with or without the outer organic layer (periostracum) proved to be valuable DNA reservoirs, with aragonite appearing as the best substrate for genomic analyses. Our work contributes to the understanding of long-term molecular preservation in biominerals and we anticipate that resulting recommendations will be helpful for future efficient and responsible genomic analyses of ancient mollusc shells.

A systematic review on microplastic contamination in marine Crustacea and Mollusca of Asia: Current scenario, concentration, characterization, polymeric risk assessment, and future Prospectives.

Microplastics (MPs) pollution has wreaked havoc on biodiversity and food safety globally. The false ingestion of MPs causes harmful effects on organisms, resulting in a decline in biodiversity. The present review comprehended the current knowledge of MP contamination in Crustacea and Mollusca from 75 peer-reviewed articles published in Asia between 2015 and 2023. A total of 79 species (27 Crustacea and 52 Mollusca) have been recorded to be contaminated with MPs. Out of the total 27 species of Crustacea, Metopograpsus quadridentatus (327.56 MPs/individual) and Balanus albicostatus (0.42 MPs/individual) showed the highest and lowest contamination, respectively. Out of the total 52 species of Mollusca, Dolabella auricularia (2325 MPs/individual) and Crassostrea gigas and Mytilus edulis (0.2 MPs/individual) showed the highest and lowest contamination, respectively. In terms of country-wise MP contamination, China has the highest number of contaminated species in both phylums among Asia. Findings of pollution indices revealed a very high risk of MP contamination in all the countries. Fiber was reported predominantly in both groups. Blue and black-colored MPs having <500 µm and <500 µm-1 mm size were found dominantly in Crustacea and Mollusca, respectively. Polypropylene was recorded as the dominant plastic polymer in both Crustacea and Mollusca. In essence, this review has provided a comprehensive insight into MP concentration in Crustacea and Mollusca of Asia, highlighting variations among species and geographic locations. This understanding is crucial for tackling urgent environmental challenges, safeguarding human health, and promoting global sustainability initiatives amid the escalating issue of plastic pollution. PRACTITIONER POINTS: Microplastic pollution has created havoc on biodiversity and food safety. A total of 27 and 52 species of crustaceans and Mollusca have been recorded to be contaminated with MPs. Metopograpsus quadridentate and Dolabella auricularia have shown higher MPs contamination. Polypropylene was recorded as the dominant plastic polymer in both crustacean and Mollusca. Findings of pollution indices revealed a very high risk of MP contamination in all the countries.

Paralytic Shellfish Toxins in Mollusks from Galicia Analyzed by a Fast Refined AOAC 2005.06 Method: Toxicity, Toxin Profile, and Inter-Specific, Spatial, and Seasonal Variations.

Paralytic shellfish poisoning is an important concern for mollusk fisheries, aquaculture, and public health. In Galicia, NW Iberian Peninsula, such toxicity has been monitored for a long time using mouse bioassay. Therefore, little information exists about the precise toxin analogues and their possible transformations in diverse mollusk species and environments. After the change in the European PSP reference method, a refinement of the Lawrence method was developed, achieving a 75% reduction in chromatogram run time. Since the beginning of 2021, when this refinement Lawrence method was accredited under the norm UNE-EN ISO/IEC 17025, it has been used in the area to determine the toxin profiles and to estimate PSP toxicity in more than 4500 samples. In this study, we have summarized three years of monitoring results, including interspecific, seasonal, and geographical variability of PSP toxicity and toxin profile. PSP was detected in more than half of the samples analyzed (55%), but only 4.4% of the determinations were above the EU regulatory limit. GTX1,4 was the pair of STX analogs that produced the highest toxicities, but GTX2,3 was found in most samples, mainly due to the reduction of GTX1,4 but also by the higher sensitivity of the method for this pair of analogs. STX seems to be mainly a product of biotransformation from GTX2,3. The studied species (twelve bivalves and one gastropod) accumulated and transformed PSP toxins to a different extent, with most of them showing similar profiles except for Spisula solida and Haliotis tuberculata. Two seasonal peaks of toxicity were found: one in spring-early summer and another in autumn, with slightly different toxin profiles during outbreaks in relation to the toxicity during valleys. In general, both the total toxicity and toxin profiles of the southernmost locations were different from those in the northern part of the Atlantic coast and the Cantabrian Sea, but this general pattern is modified by the PSP history of some specific locations.

Taxonomic, phylogenetic, and functional diversity of mollusk death assemblages in coral reef and seagrass sediments from two shallow gulfs in Western Cuban Archipelago.

Mollusk death assemblages are formed by shell remnants deposited in the surficial mixed layer of the seabed. Diversity patterns in tropical marine habitats still are understudied; therefore, we aimed to investigate the taxonomic, phylogenetic, and functional diversity of mollusk death assemblages at regional and local scales in coral reef sands and seagrass meadows. We collected sediment samples at 11 sites within two shallow gulfs in the Northwestern Caribbean Sea and Southeastern Gulf of Mexico. All the shells were counted and identified to species level and classified into biological traits. We identified 7113 individuals belonging to 393 species (290 gastropods, 94 bivalves, and nine scaphopods). Diversity and assemblage structure showed many similarities between gulfs given their geological and biogeographical commonalities. Reef sands had higher richness than seagrasses likely because of a more favorable balance productivity-disturbance. Reef sands were dominated by epifaunal herbivores likely feeding on microphytobenthos and bysally attached bivalves adapted to intense hydrodynamic regime. In seagrass meadows, suspension feeders dominated in exposed sites and chemosynthetic infaunal bivalves dominated where oxygen replenishment was limited. Time averaging of death assemblages was likely in the order of 100 years, with stronger effects in reef sands compared to seagrass meadows. Our research provides evidence of the high taxonomic, phylogenetic, and functional diversity of mollusk death assemblages in tropical coastal sediments as result of the influence of scale-related processes and habitat type. Our study highlights the convenience of including phylogenetic and functional traits, as well as dead shells, for a more complete assessment of mollusk biodiversity.

Nutraceutical and Medicinal Importance of Marine Molluscs.

Marine molluscs are of enormous scientific interest due to their astonishing diversity in terms of their size, shape, habitat, behaviour, and ecological roles. The phylum Mollusca is the second most common animal phylum, with 100,000 to 200,000 species, and marine molluscs are among the most notable class of marine organisms. This work aimed to show the importance of marine molluscs as a potential source of nutraceuticals as well as natural medicinal drugs. In this review, the main classes of marine molluscs, their chemical ecology, and the different techniques used for the extraction of bioactive compounds have been presented. We pointed out their nutraceutical importance such as their proteins, peptides, polysaccharides, lipids, polyphenolic compounds pigments, marine enzymes, minerals, and vitamins. Their pharmacological activities include antimicrobial, anticancer, antioxidant, anti-inflammatory, and analgesic activities. Moreover, certain molluscs like abalones and mussels contain unique compounds with potential medicinal applications, ranging from wound healing to anti-cancer effects. Understanding the nutritional and therapeutic value of marine molluscs highlights their significance in both pharmaceutical and dietary realms, paving the way for further research and utilization in human health.

Immunotherapeutic Potential of Mollusk Hemocyanins in Murine Model of Melanoma.

The development of antitumor drugs and therapy requires new approaches and molecules, and products of natural origin provide intriguing alternatives for antitumor research. Gastropodan hemocyanins-multimeric copper-containing glycoproteins have been used in therapeutic vaccines and antitumor agents in many cancer models. MATERIALS AND METHODS: We established a murine model of melanoma by challenging C57BL/6 mice with a B16F10 cell line for solid tumor formation in experimental animals. The anticancer properties of hemocyanins isolated from the marine snail Rapana thomasiana (RtH) and the terrestrial snail Helix aspersa (HaH) were evaluated in this melanoma model using various schemes of therapy. Flow cytometry, ELISA, proliferation, and cytotoxicity assays, as well as histology investigations, were also performed. RESULTS: Beneficial effects on tumor growth, tumor incidence, and survival of tumor-bearing C57BL/6 mice after administration of the RtH or HaH were observed. The generation of high titers of melanoma-specific IgM antibodies, pro-inflammatory cytokines, and tumor-specific CTLs, and high levels of tumor-infiltrated M1 macrophages enhanced the immune reaction and tumor suppression. DISCUSSION: Both RtH and HaH exhibited promising properties for applications as antitumor therapeutic agents and future experiments with humans.

Transcriptional landscape of small non-coding RNAs reveals diversity of categories and functions in molluscs.

Small non-coding RNAs (sncRNAs) are non-coding RNA molecules that play various roles in metazoans. Among the sncRNAs, microRNAs (miRNAs) guide post-translational gene regulation during cellular development, proliferation, apoptosis, and differentiation, while PIWI-interacting RNAs (piRNAs) suppress transposon activity to safeguard the genome from detrimental insertion mutagenesis. While an increasing number of piRNAs are being identified in the soma and germlines of various organisms, they are scarcely reported in molluscs. To unravel the small RNA (sRNA) expression patterns and genomic function in molluscs, we generated a comprehensive sRNA dataset by sRNA sequencing (sRNA-seq) of eight mollusc species. Abundant miRNAs were identified and characterized in all investigated molluscs, and ubiquitous piRNAs were discovered in both somatic and gonadal tissues in six of the investigated molluscs, which are more closely associated with transposon silencing. Tens of piRNA clusters were also identified based on the genomic mapping results, which varied among different tissues and species. Our dataset serves as important reference data for future genomic and genetic studies on sRNAs in these molluscs and related species, especially in elucidating the ancestral state of piRNAs in bilaterians.

Laetoli, Tanzania: Extant terrestrial mollusc faunas shed new light on climate and palaeoecology at a Pliocene hominin site.

Laetoli, Tanzania is one of the most important palaeontological and palaeoanthropological localities in Africa. We report on a survey of the extant terrestrial gastropod faunas of the Laetoli-Endulen area, examine their ecological associations and re-examine the utility of Pliocene fossil molluscs in palaeoenvironmental reconstruction. Standardised collecting at 15 sites yielded 7302 individuals representing 58 mollusc species. Significant dissimilarities were found among the faunas of three broad habitat types: forest, woodland/bushland and open (grassland and scattered, xeric shrubland). Overall, more species were recorded in the woodland/bushland sites than in the forest sites. Open sites were less diverse. Environmental factors contributing most strongly to the separation of habitat types were aridity index and elevation. The results are supplemented with new mollusc data from the Mbulu Plateau south of Lake Eyasi, and compared to the list of species cumulatively recorded from the Ngorongoro area. Some regional variation is apparent and historical factors may explain the absence of some fossil taxa from Laetoli today. Differences in seasonality separated upland forest sites on the Mbulu plateau from those at Lemagurut at Laetoli. Indicator species were identified for each habitat. These included several large-bodied species analogous to the Laetoli Pliocene fossil species that were then used for palaeoenvironmental reconstruction. Based on the estimated aridity index, and adopting the widely used United Nations Environment Programme (UNEP) global climate classification, the four stratigraphic subunits of the Upper Laetolil Beds (3.6-3.85 Ma) would be placed in either the UNEP's Dry Sub-humid or Semi-arid climate classes, whereas the Upper Ndolanya Beds (2.66 Ma) and Lower Laetolil Beds (3.85-<4.36 Ma) would be assigned to the Humid and Semi-arid climate classes respectively. Pliocene precipitation at Laetoli is estimated as 847-965 mm per year, refining previous estimates. This is close or slightly higher than the present mean annual precipitation, and is likely to have corresponded to a mosaic of forest, woodland and bushland within a grassland matrix consistent with other reconstructions.

High-resolution vision in pelagic polychaetes.

High-resolution object vision - the ability to separate, classify, and interact with specific objects in the environment against the visual background - has only been conclusively shown to have evolved in three of the thirty-five animal phyla: chordates, arthropods, and mollusks (cephalopods)1. However, alciopid polychaetes (Phyllodocidae, Alciopini), which possess a pair of bulbous camera-type eyes, have also been hypothesized to achieve high acuity. In this study, we examined three species of night-active pelagic alciopids from the Mediterranean Sea. Our optical, morphological, and electrophysiological investigations show that their eyes have high spatial acuity and temporal resolution, supporting the notion that they are capable of active, high-resolution object vision. These results encourage interesting hypotheses about the visual ecology of these enigmatic polychaetes.

Distribution and composition of seafloor litter and associated macrofouling organisms in the Northeastern Mediterranean Sea.

Composition, and density of marine litter and associated macrofouling organisms was assessed in the continental shelf of the Northeastern Mediterranean Sea. A total of 943 litter items weighing 388 kg were collected during 34 hauls. Plastic comprised 72 % of the total litter found on the seafloor. The mean number and weight of ML was 4241 ± 1333 items/km2 and 368 ± 87 kg/km2. Depth and distance from the shore were not identified as a significant factor affecting both the number and weight of litter. A total of 20 fouling species and eggs belonging to Mollusca, Porifera, Cnidaria, Bryozoa, Annelida, Arthropoda, and Chordata were found on marine litter. An alien Mollusca species Pinctada imbricate was also found on plastic litter. Our results confirmed that marine litter is a vector transporting a variety of organisms including alien species and being a threat for the biodiversity and human health in the Mediterranean Sea.

Comparative analysis of tropomyosin allergenicity in three different species of molluscs: insights into the role of amino acid composition in IgE epitopes.

Limited research has been conducted on the differences in allergenicity among Alectryonella plicatula tropomyosin (ATM), Haliotis discus hannai tropomyosin (HTM), and Mimachlamys nobilis tropomyosin (MTM) in molluscs. Our study aimed to comprehensively analyze and compare their immunoreactivity, sensitization, and allergenicity while simultaneously elucidating the underlying molecular mechanisms involved. We assessed the immune binding activity of TM utilizing 86 sera from allergic patients and evaluated sensitization and allergenicity through two different types of mouse models. The dot-blot and basophil activation test assays revealed strong immunoreactivity for HTM, ATM, and MTM, with HTM exhibiting significantly lower levels compared to ATM. In the BALB/c mouse sensitization model, all TM groups stimulated the production of specific antibodies, elicited IgE-mediated immediate hypersensitivity responses, and caused an imbalance in the IL-4/IFN-γ ratio. Similarly, in the BALB/c mouse model of food allergy, all TM variants induced IgE-mediated type I hypersensitivity responses, leading to the development of food allergies characterized by clinical symptoms and an imbalance in the IL-4/IFN-γ ratio. The stimulation ability of sensitization and the severity of food allergies consistently ranked as ATM > MTM > HTM. Through an in-depth analysis of non-polar amino acid frequency and polar hydrogen bonds, HTM exhibited higher frequencies of non-polar amino acids in its amino acid sequence and IgE epitopes, in comparison with ATM and MTM. Furthermore, HTM demonstrated a lower number of polar hydrogen bonds in IgE epitopes. Overall, HTM exhibited the lowest allergenic potential in both allergic patients and mouse models, likely due to its lower polarity in the amino acid sequence and IgE epitopes.

Insecticidal activity of Ageratina adenophora (Asteraceae) extract against Limax maximus (Mollusca, Limacidae) at different developmental stages and its chemical constituent analysis.

Limax maximus, or great gray slug, is a common agriculture pest. The pest infests crops during their growth phase, creating holes in vegetable leaves, particularly in seedlings and tender leaves. A study was conducted to assess the insecticidal activity of Ageratina adenophora extract against these slugs. Factors such as fecundity, growth, hatching rate, offspring survival rate, protective enzyme activity, and detoxifying enzyme activity were examined in slugs exposed to the extract's sublethal concentration (LC50) for two different durations (24 and 48 h). The phytochemical variability of the extracts was also studied. The LC50 value of the A. adenophora extract against L. maximus was 35.9 mg/mL. This extract significantly reduced the hatching rate of eggs and the survival rate of offspring hatched from exposed eggs compared with the control. The lowest rates were observed in those exposed for 48 h. The survival, growth, protective enzyme, and detoxification activity of newly hatched and 40-day-old slugs decreased. The A. adenophora extract contained tannins, flavonoids, and saponins, possibly contributing to their biological effects. These results suggest that the extract could be used as an alternative treatment for slug extermination, effectively controlling this species.

Community Structure and Water Quality Assessment of Benthic Macroinvertebrates in Hongze Lake.

This study investigated the species, density, biomass and physicochemical factors of benthic macroinvertebrates in Hongze Lake from 2016 to 2020. Redundancy analysis (RDA) was used to analyze the relationship between physicochemical parameters and the community structure of macroinvertebrates. Macroinvertebrate-based indices were used to evaluate the water quality conditions in Hongze Lake. The results showed that a total of 50 benthic species (10 annelids, 21 arthropods and 19 mollusks) were collected. The community structure of benthic macroinvertebrates varied in time and space. The dominant species were Limnodrilus hoffmeisteri (L.hoffmeisteri), Corbicula fluminea (C.fluminea), Nephtys oligobranchia (N.oligobranchia). In 2016, arthropods such as Grandidierella sp. were the dominant species of benthos in Hongze Lake while annelids and mollusks dominated from 2017 to 2020, such as L.hoffmeisteri, N.oligobranchia, C.fluminea. The benthic fauna of Chengzi Lake and Lihewa District were relatively abundant and showed slight variation, while the benthic macroinvertebrates of the Crossing the water area were few and varied greatly. RDA showed that changes in benthic macroinvertebrate structure were significantly correlated with dissolved oxygen (DO), Pondus Hydrogenii (pH) and transparency (SD). The Shannon Wiener, Pielou, and Margalef indices indicate that Hongze Lake is currently in a moderately polluted state. Future studies should focus on the combined effects of various physicochemical indicators and other environmental factors on benthic communities.

A dataset of thermal preferences for Mediterranean demersal and benthic macrofauna.

Climate change is swiftly reshaping marine ecosystems, affecting different biological levels. Changes in thermal conditions profoundly influence ectotherms' growth, behaviour, and functions, making knowledge of species' thermal preferences (TP) crucial for understanding their responses to ongoing warming. However, obtaining this data is challenging due to limited studies, especially for deep-sea demersal and bottom-dwelling species. Here, we present the MedFaunaTP dataset, a collection of survey-based TPs for 939 Mediterranean species of fish, crustaceans, molluscs, echinoderms, cnidarians, and tunicates calculated using species abundance data obtained from the international bottom-trawl survey in the Mediterranean (MEDITS) and bottom temperature data derived from the Copernicus Monitoring Environment Marine Service. MEDITS estimates are based on species biomass indices from 27587 sampling stations, collected from 1994 to 2020, covering the northern Mediterranean Sea and spanning depths from 10 to 800 m. The MedFaunaTP dataset may serves as a valuable resource for understanding and addressing marine ecosystem ecological, conservation, and management challenges in the context of climate change and associated global warming.

The genome of the rayed Mediterranean limpet Patella caerulea (Linnaeus, 1758).

Patella caerulea (Linnaeus, 1758) is a mollusc limpet species of the class Gastropoda. Endemic to the Mediterranean Sea, it is considered a keystone species due to its primary role in structuring and regulating the ecological balance of tidal and subtidal habitats. It is currently being used as a bioindicator to assess the environmental quality of coastal marine waters and as a model species to understand adaptation to ocean acidification. Here, we provide a high-quality reference genome assembly and annotation for P. caerulea. We generated ∼30 Gb of Pacific Biosciences high-fidelity data from a single individual and provide a final 749.8 Mb assembly containing 62 contigs, including the mitochondrial genome (14,938 bp). With an N50 of 48.8 Mb and 98% of the assembly contained in the 18 largest contigs, this assembly is near chromosome-scale. Benchmarking Universal Single-Copy Orthologs scores were high (Mollusca, 87.8% complete; Metazoa, 97.2% complete) and similar to metrics observed for other chromosome-level Patella genomes, highlighting a possible bias in the Mollusca database for Patellids. We generated transcriptomic Illumina data from a second individual collected at the same locality and used it together with protein evidence to annotate the genome. A total of 23,938 protein-coding gene models were found. By comparing this annotation with other published Patella annotations, we found that the distribution and median values of exon and gene lengths was comparable with other Patella species despite different annotation approaches. The present high-quality P. caerulea reference genome, available on GenBank (BioProject: PRJNA1045377; assembly: GCA_036850965.1), is an important resource for future ecological and evolutionary studies.

Shell-based genus-level reclassification of the Family Vasidae (Mollusca: Neogastropoda).

The neogastropod family Vasidae comprises a small group of Late Eocene to Recent neogastropods with large, often ornate shells. A new, shell-based morphological classification of the family is proposed, in which ten genera are recognized: Altivasum Hedley, 1914, Aristovasum gen. nov. (type species: Turbinella cassiforme Kiener, 1840), Florivasum gen. nov. (type species: Turbinella tubifera Anton, 1838), Globivasum Abbott, 1950 (type species: Turbinella nuttingi Henderson, 1919, but expanded here), Hystrivasum Olsson & Petit, 1964 (type species: Vasum horridum Heilprin, 1887), Rhinovasum gen. nov. (type species: Voluta rhinoceros Gmelin, 1791), Siphovasum Rehder & Abbott, 1951, Tudivasum Rosenberg & Petit, 1987, Vasum Rding, 1798 (here restricted to a reef-associated group of three species typified by Murex turbinellus Linnaeus, 1758), and Volutella Perry, 1810 (here resurrected from synonymy with Vasum, type species Voluta muricata Born, 1778). Biogeographically the Vasidae exhibit a deep divergence between the Atlantic-East Pacific and Indo-West Pacific realms dating to the Early Miocene.

Single-cell transcriptomics of the human parasite Schistosoma mansoni first intra-molluscan stage reveals tentative tegumental and stem-cell regulators.

Schistosomiasis is a major Neglected Tropical Disease, caused by the infection with blood flukes in the genus Schistosoma. To complete the life cycle, the parasite undergoes asexual and sexual reproduction within an intermediate snail host and a definitive mammalian host, respectively. The intra-molluscan phase provides a critical amplification step that ensures a successful transmission. However, the cellular and molecular mechanisms underlying the development of the intra-molluscan stages remain poorly understood. Here, single cell suspensions from S. mansoni mother sporocysts were produced and sequenced using the droplet-based 10X Genomics Chromium platform. Six cell clusters comprising two tegument, muscle, neuron, parenchyma and stem/germinal cell clusters were identified and validated by in situ hybridisation. Gene Ontology term analysis predicted key biological processes for each of the clusters, including three stem/germinal sub-clusters. Furthermore, putative transcription factors predicted for stem/germinal and tegument clusters may play key roles during parasite development and interaction with the intermediate host.

A multiscale computational framework for the development of spines in molluscan shells.

From mathematical models of growth to computer simulations of pigmentation, the study of shell formation has given rise to an abundant number of models, working at various scales. Yet, attempts to combine those models have remained sparse, due to the challenge of combining categorically different approaches. In this paper, we propose a framework to streamline the process of combining the molecular and tissue scales of shell formation. We choose these levels as a proxy to link the genotype level, which is better described by molecular models, and the phenotype level, which is better described by tissue-level mechanics. We also show how to connect observations on shell populations to the approach, resulting in collections of molecular parameters that may be associated with different populations of real shell specimens. The approach is as follows: we use a Quality-Diversity algorithm, a type of black-box optimization algorithm, to explore the range of concentration profiles emerging as solutions of a molecular model, and that define growth patterns for the mechanical model. At the same time, the mechanical model is simulated over a wide range of growth patterns, resulting in a variety of spine shapes. While time-consuming, these steps only need to be performed once and then function as look-up tables. Actual pictures of shell spines can then be matched against the list of existing spine shapes, yielding a potential growth pattern which, in turn, gives us matching molecular parameters. The framework is modular, such that models can be easily swapped without changing the overall working of the method. As a demonstration of the approach, we solve specific molecular and mechanical models, adapted from available theoretical studies on molluscan shells, and apply the multiscale framework to evaluate the characteristics of spines from three distinct populations of Turbo sazae.