Slipper Limpet (Crepidula fornicata) Shells Support In Vitro Osteogenesis of Human Adipose-Derived Stem Cells

This study aimed to investigate a cost-effective alternative to man-made calcium phosphate ceramics for treating bone defects. The slipper limpet is an invasive species in European coastal waters, and its shells composed of calcium carbonate could potentially be a cost-effective source of bone graft substitutes. This research analyzed the mantle of the slipper limpet (Crepidula fornicata) shells to enhance in vitro bone formation. Discs machined from the mantle of C. fornicata were analyzed using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), X-ray crystallography (XRD), Fourier-transform infrared spectroscopy (FT-IR) and profilometry. Calcium release and bioactivity were also studied. Cell attachment, proliferation, and osteoblastic differentiation (RT-qPCR and alkaline phosphatase activity) were measured in human adipose-derived stem cells grown on the mantle surface. The mantle material was mainly composed of aragonite and showed a sustained Ca²⁺ release at physiological pH. In addition, apatite formation was observed in simulated body fluid after three weeks, and the materials supported osteoblastic differentiation. Overall, our findings suggest the mantle of C. fornicata shows potential as a material for fabricating bone graft substitutes and structural biomaterials for bone regeneration.

The Marine Gastropod Crepidula fornicata Remains Resilient to Ocean Acidification Across Two Life History Stages

Rising atmospheric CO₂ reduces seawater pH causing ocean acidification (OA). Understanding how resilient marine organisms respond to OA may help predict how community dynamics will shift as CO₂ continues rising. The common slipper shell snail Crepidula fornicata is a marine gastropod native to eastern North America that has been a successful invader along the western European coastline and elsewhere. It has also been previously shown to be resilient to global change stressors. To examine the mechanisms underlying C. fornicata’s resilience to OA, we conducted two controlled laboratory experiments. First, we examined several phenotypes and genome-wide gene expression of C. fornicata in response to pH treatments (7.5, 7.6, and 8.0) throughout the larval stage and then tested how conditions experienced as larvae influenced juvenile stages (i.e., carry-over effects). Second, we examined genome-wide gene expression patterns of C. fornicata larvae in response to acute (4, 10, 24, and 48 h) pH treatment (7.5 and 8.0). Both C. fornicata larvae and juveniles exhibited resilience to OA and their gene expression responses highlight the role of transcriptome plasticity in this resilience. Larvae did not exhibit reduced growth under OA until they were at least 8 days old. These phenotypic effects were preceded by broad transcriptomic changes, which likely served as an acclimation mechanism for combating reduced pH conditions frequently experienced in littoral zones. Larvae reared in reduced pH conditions also took longer to become competent to metamorphose. In addition, while juvenile sizes at metamorphosis reflected larval rearing pH conditions, no carry-over effects on juvenile growth rates were observed. Transcriptomic analyses suggest increased metabolism under OA, which may indicate compensation in reduced pH environments. Transcriptomic analyses through time suggest that these energetic burdens experienced under OA eventually dissipate, allowing C. fornicata to reduce metabolic demands and acclimate to reduced pH. Carry-over effects from larval OA conditions were observed in juveniles; however, these effects were larger for more severe OA conditions and larvae reared in those conditions also demonstrated less transcriptome elasticity. This study highlights the importance of assessing the effects of OA across life history stages and demonstrates how transcriptomic plasticity may allow highly resilient organisms, like C. fornicata, to acclimate to reduced pH environments.

Development and validation of eDNA markers for the detection of Crepidula fornicata in environmental samples

The invasive Crepidula fornicata caused major problems along the European Atlantic coast, especially in France and Netherlands where high densities leads on changes in the habitat, disturb native marine wildlife as well as it originates competition for space and food. Despite its dangerous invasive nature, regular monitoring to alert about its presence in risk areas, like the south Bay of Biscay (Spain and south France), is not done yet. Here, we developed a species-specific marker to detect the presence of C. fornicata in environmental samples (eDNA) of seawater. The novel C. fornicata specific primers amplified a region of 239 bp within the COI gen. We employed this tool to check its presence in 6 estuaries of the Cantabrian Sea, an area comprised between the Spanish and French limits of the previously reported presence of this limpet in the south Bay of Biscay. The presence of C. fornicata was confirmed in A Coruña (Galicia, Spain), Eo and Villaviciosa estuaries (Asturias, Spain) while it was not detected in Santander, Bilbao (Spain), and Bayonne (France). This new method to detect C. fornicata could be easily implemented in regular monitoring to prevent and manage future invasions of this species.

Active management is required to turn the tide for depleted Ostrea edulis stocks from the effects of overfishing, disease and invasive species

The decline of the European oyster Ostrea edulis across its biogeographic range has been driven largely by over-fishing and anthropogenic habitat destruction, often to the point of functional extinction. However, other negatively interacting factors attributing to this catastrophic decline include disease, invasive species and pollution. In addition, a relatively complex life history characterized by sporadic spawning renders O. edulis biologically vulnerable to overexploitation. As a viviparous species, successful reproduction in O. edulis populations is density dependent to a greater degree than broadcast spawning oviparous species such as the Pacific oyster Crassostrea (Magallana) gigas. Here, we report on the benthic assemblage of O. edulis and the invasive gastropod Crepidula fornicata across three actively managed South coast harbors in one of the few remaining O. edulis fisheries in the UK. Long-term data reveals that numbers of O. edulis sampled within Chichester Harbour have decreased by 96%, in contrast numbers of C. fornicata sampled have increased by 441% over a 19-year period. The recent survey data also recorded extremely low densities of O. edulis, and extremely high densities of C. fornicata, within Portsmouth and Langstone Harbours. The native oyster’s failure to recover, despite fishery closures, suggests competitive exclusion by C. fornicata is preventing recovery of O. edulis, which is thought to be due to a lack of habitat heterogeneity or suitable settlement substrate. Large scale population data reveals that mean O. edulis shell length and width has decreased significantly across all years and site groups from 2015 to 2017, with a narrowing demographic structure. An absence of juveniles and lack of multiple cohorts in the remaining population suggests that the limited fishing effort exceeds biological output and recruitment is poor. In the Langstone & Chichester 2017 sample 98% of the population is assigned to a single cohort (modal mean 71.20 ± 8.78 mm, maximum length). There is evidence of small scale (<5 km) geographic population structure between connected harbors; the 2015 Portsmouth and Chichester fishery populations exhibited disparity in the most frequent size class with 36% within 81–90 mm and 33.86% within 61–70 mm, respectively, the data also indicates a narrowing demographic over a short period of time. The prevalence of the disease Bonamiosis was monitored and supports this microgeographic population structure. Infection rates of O. edulis by Bonamia ostreae was 0% in Portsmouth Harbor (n = 48), 4.1% in Langstone (n = 145) and 21.3% in Chichester (n = 48) populations. These data collectively indicate that O. edulis is on the brink of an ecological collapse within the Solent harbors. Without effective intervention to mitigate the benthic dominance by C. fornicata in the form of biologically relevant fishery policy and the management of suitable recruitment substrate these native oyster populations could be lost.

The invasive, non-native slipper limpet Crepidula fornicata is poorly adapted to sediment burial

The American slipper limpet Crepidula fornicata is an invasive, non-native species (INNS) abundant along the European coast. Its further distribution may be facilitated by activities such as dredging and spoil disposal, and the aim of this study was to assess whether C. fornicata is able to survive sediment burial. The slipper limpet was found attached to hard substratum in intertidal areas, but it was absent at a nearby subtidal dredge spoil site. In laboratory experiments 22% of C. fornicata emerged when buried under a 2 cm sediment-layer; only half of them survived. When buried under ≥6 cm none re-surfaced or survived. The results provided evidence that C. fornicata is poorly adapted to adjust its vertical position in sediment and is killed by sudden burial underneath 2 to 6 cm of sediment. The combined laboratory experiments and field surveys suggested that C. fornicata has limited scope to survive the dredge spoil disposal process.

Molecular, phylogenetic and developmental analyses of Sall proteins in bilaterians

Background

Sall (Spalt-like) proteins are zinc-finger transcription factors involved in a number of biological processes. They have only been studied in a few model organisms, such as Drosophila melanogaster, Caenorhabditis elegans, Schmidtea mediterranea and some vertebrates. Further taxon sampling is critical to understand the evolution and diversification of this protein and its functional roles in animals.

Results

Using genome and transcriptome mining, we confirmed the presence of sall genes in a range of additional animal taxa, for which their presence had not yet been described. We show that sall genes are broadly conserved across the Bilateria, and likely appeared in the bilaterian stem lineage. Our analysis of the protein domains shows that the characteristic arrangement of the multiple zinc-finger domains is conserved in bilaterians and may represent the ancient arrangement of this family of transcription factors. We also show the existence of a previously unknown zinc-finger domain. In situ hybridization was used to describe the gene expression patterns in embryonic and larval stages in two species of snails: Crepidula fornicata and Lottia gigantea. In L. gigantea, sall presents maternal expression, although later on the expression is restricted to the A and B quadrants during gastrulation and larval stage. In C. fornicata, sall has no maternal expression and it is expressed mainly in the A, C and D quadrants during blastula stages and in an asymmetric fashion during the larval stage.

Discussion

Our results suggest that the bilaterian common ancestor had a Sall protein with at least six zinc-finger domains. The evolution of Sall proteins in bilaterians might have occurred mostly as a result of the loss of protein domains and gene duplications leading to diversification. The new evidence complements previous studies in highlighting an important role of Sall proteins in bilaterian development. Our results show maternal expression of sall in the snail L. gigantea, but not C. fornicata. The asymmetric expression shown in the ectoderm of the trochophore larva of snails is probably related to shell/mantle development. The observed sall expression in cephalic tissue in snails and some other bilaterians suggests a possible ancestral role of sall in neural development in bilaterians.

The seminal receptacle and implications for reproductive processes in the invasive gastropod Crepidula fornicata

The calyptraeid gastropod Crepidula fornicata is the object of considerable research attention, due to its invasive status in the North-Eastern Atlantic, its introduction to habitats throughout the Northern hemisphere, and its scientific interest as a model organism for the study of developmental and reproductive processes in the Metazoa. Since the knowledge concerning the structural foundations for its reproductive processes is surprisingly weak, we investigated the seminal receptacle, a key structure in the reproductive biology of other metazoans, using histology, scanning electron and transmission electron microscopy. The seminal receptacle consists of 9-11 lobes, each subdivided into small, narrow lobules. The inner epithelium of the lobules appears to be highly dynamic, characterised by the perforation and attachment of received spermatozoa, the progressive degeneration of this epithelium, and the concomitant detachment of the spermatozoa. The allocation of spermatozoa to many different lobules, in different phases, may explain the extended reproductive season of C. fornicata, and thereby contribute to its colonizing and invasive success. The same compartmentalisation, as well as the complete covering of the inner epithelium of the lobules by spermatozoa and the large amount of spermatozoan debris in the lumina, suggest that the C. fornicata seminal receptacle may be a site of sperm competition in this polyandrous species.

CRISPR/Cas9-mediated genome modification in the mollusc, Crepidula fornicata

The discovery and application of the CRISPR/Cas9 genome editing method has greatly enhanced the ease with which transgenic manipulation can occur. We applied this technology to the mollusc, Crepidula fornicata, and have successfully created transgenic embryos expressing mCherry fused to endogenous β-catenin. Specific integration of the fluorescent reporter was achieved by homologous recombination with a β-catenin-specific donor DNA containing the mCherry coding sequence. This fluorescent gene knock-in strategy permits in vivo observations of β-catenin expression during embryonic development and represents the first demonstration of CRISPR/Cas9-mediated transgenesis in the Lophotrochozoa superphylum. The CRISPR/Cas9 method is a powerful and economical tool for genome modification and presents an option for analysis of gene expression in not only major model systems, but also in those more diverse species that may not have been amenable to the classic methods of transgenesis. This approach will allow one to generate transgenic lines of snails for future studies.