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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. [ABSTRACT FROM AUTHOR]

Asymmetries are essential for proper organization and function of organ systems. Genetic studies in bilaterians have shown signaling through the Nodal/Smad2 pathway plays a key, conserved role in the establishment of body asymmetries. Although the main molecular players in the network for the establishment of left-right asymmetry (LRA) have been deeply described in deuterostomes, little is known about the regulation of Nodal signaling in spiralians. Here, we identified orthologs of the egf-cfc gene, a master regulator of the Nodal pathway in vertebrates, in several invertebrate species, which includes the first evidence of its presence in non-deuterostomes. Our functional experiments indicate that despite being present, egf-cfc does not play a role in the establishment of LRA in gastropods. However, experiments in zebrafish suggest that a single amino acid mutation in the egf-cfc gene in at least the common ancestor of chordates was the necessary step to induce a gain of function in LRA regulation. This study shows that the egf-cfc gene likely appeared in the ancestors of deuterostomes and "protostomes", before being adopted as a mechanism to regulate the Nodal pathway and the establishment of LRA in some lineages of deuterostomes. [ABSTRACT FROM AUTHOR]

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.

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.

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. [ABSTRACT FROM AUTHOR]

Abstract 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 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 (

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. • The first highly sensitive C. fornicata specific marker was designed to detect this invasive limpet in environmental samples. • Six Spanish and French estuaries in the South Bay of Biscay were monitorized to detect Crepidula fornicata employing eDNA. • The results confirmed the presence of this invasive mollusc in Galicia and Asturias, not in Santander, Bilbao and Bayonne. • Spreading of the invasive C. fornicata in European coasts can be regularly monitored using this new molecular tool. [ABSTRACT FROM AUTHOR]

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 themanagement of suitable recruitment substrate these native oyster populations could be lost. [ABSTRACT FROM AUTHOR]

Two non-indigenous species of slipper limpets (Gastropoda: Calyptraeidae) have been recorded in NW Europe: Crepidula fornicata and Crepipatella dilatata. Although the former is widespread distributed in European Atlantic, records on Portuguese coasts are scarce. Regarding C. dilatata , it has been only reported in the southern Galician Rías (NW Spain). In this study, C. dilatata is reported for first time on Portugal and the distribution of these two species were studied in the North and Centre of Portugal. Moreover, abundance, distribution and structure of C. dilatata populations were compared between two intertidal habitats. Abundance and structure of C. dilatata populations showed no significant differences between habitats, suggesting that the species is well established in both. Regarding size-frequencies, bigger individuals were more frequent in soft bottoms. The recent development of oyster aquaculture in Portugal and the variety of substrates in which these NIS have been found could facilitate future introductions in nearby locations. [Display omitted] • Presence of Crepidula fornicata and Crepipatella dilatata in Portugal. • Crepidula fornicata and Crepipatella dilatata appeared on several substrates. • Crepipatella dilatata living in soft bottoms are bigger than in rocky shores. • Baseline values of presence and abundance are provided for both species in Portugal. [ABSTRACT FROM AUTHOR]

The slipper limpet Crepidula fornicata is an emblematic invasive species along the northeast Atlantic coast. This gregarious gastropod lives in stacks of several individuals and forms extended beds in shallow subtidal areas. The effects of this engineer species on the colonized habitat can be physical (e.g., presence of hard-shell substrates with uneven topography) or biological (e.g., nutrient enrichment by direct excretion or via biodeposition). We hypothesized that through biological activity, nutrient fluxes at the sediment-water interface are enhanced, leading to stimulated primary productivity by microphytobenthos (MPB) associated with Crepidula beds. To test this fertilization hypothesis, we conducted a 10-day mesocosm experiment using C. fornicata (live and dead) placed on top of sieved and homogenized sediment collected in situ. We used hyperspectral imaging to non-invasively map the development of MPB biomass, and to assess the potential influence of C. fornicata and its spatial extent. Our results showed that live C. fornicata significantly promote MPB growth through both physical and biological effects, with the biological effect dominating over the pure physical one. The highest stimulation was observed on the shells, suggesting that dissolved metabolic products excreted by C. fornicata were likely the main factor stimulating MPB growth in our short-term experiment. Our findings provide first direct evidence that stimulation of MPB growth by the biological activity of larger benthic epifauna occurs not only in intertidal but also in shallow subtidal habitats. More research is needed to assess the contribution of this fertilization effect to the trophic functioning of subtidal benthic systems.

The slipper limpet Crepidula fornicata ranks among the main invasive species on French coasts and is known to cause ecological impacts on food web structure and nutrient cycling. This study investigated the effect of C. fornicata on different components of benthic megafauna diversity (species composition, α-, β- and γ-diversity). In Arcachon Bay (France), C. fornicata was present in 58% of the 221 sampling stations. Crepidula fornicata was particularly abundant in four of the main benthic megafauna assemblages, suggesting a non-random distribution of its population. The mean number of megafauna species per station (α-diversity) was 11 with C. fornicata vs six without. Conversely, community similarity among stations (β-diversity) was higher when C. fornicata biomass increased. Opposing α- and β-diversity trends in the presence of C. fornicata explained the similarity of the global number of species (γ-diversity) between both situations (with and without C. fornicata). These results highlighted how this exotic engineer species acted on different types of diversity: the presence of C. fornicata increased the number of species per sample (α-diversity) but homogenized the benthic community (decreasing β-diversity) in comparison with stations where C. fornicata was absent. Crepidula fornicata stock in Arcachon Bay was also monitored and compared with 1999. The spread of C. fornicata between 1999 and 2011 has been limited with a 318 t stock which was not statistically different than the previous estimate performed in 1999. However, the mean length of C. fornicata collected in 2011 was significantly smaller, mainly due to a higher proportion of small individuals. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Estuaries are highly productive habitats that generate more organic material than other areas of comparable size, such as forests, meadows or agricultural lands. They exhibit high biodiversity and host relevant species, which can be at risk because these areas are most affected by human activities. In this study, environmental DNA (eDNA) and metabarcoding analyses were performed in two estuaries within the Bay of Biscay that are important in terms of seafood production (Ría del Eo and Ría de Villaviciosa, Asturias, Northern Spain). The main goal was to assess the potential of these novel tools to detect possible introductions of non-indigenous species. Alien genera that might have been introduced through exotic shellfish cultures in these estuaries were detected despite limited sampling. Of the NIS found, Crepidula fornicata was the only one that was already included in the Spanish invasive species catalogue ( BOE, 2013 ). After the initial invasive species detection through the metabarcoding study, post-NGS samplings and classical DNA barcoding were performed, and they confirmed the presence of the highly invasive species C. fornicata in these estuaries. Although metabarcoding still has some drawbacks, such as a lack of universal PCR primers and reference sequences for all the species in the databases as well as frequent false positives, it represents a powerful tool that can facilitate the monitoring and management of these important ecosystems, especially if it is accompanied by post-NGS samplings to confirm species occurrences. [ABSTRACT FROM AUTHOR]

The north-American marine gastropod Crepidula fornicata (Linné 1758), commonly called slipper limpet, has been introduced accidentally in Great Britain, along with American oysters ( Crassostrea virginica ) at the end of the 19th century. Its spreading, enhanced by oyster transport and international shipping, turned into invasion of a lot of benthic grounds along the North-European coasts. When local conditions are favorable to larval confinement and adult growth, the invasion by very dense populations may deeply change initially sandy or muddy benthic communities into similar “slipper limpet communities”. Competition for space eliminates several species of native infauna, and hampers the survival of some epibenthic bivalves such as the scallop Pecten maximus . As the clogging of dredges by superabundant slipper limpets drastically limits scallop fishing, some insight in the future distribution and abundance of both species ( Crepidula and Pecten ) seems necessary, especially in the English Channel where the scallop is intensively harvested. An original model, storing in a “intraspecific matching matrix” the numbers of pairs of aged animals present in the slipper limpet chains, has been developed to take into account the year-class association and stack formation specific to Crepidula fornicata. Then, an “interspecific matching matrix” component has been added to that “intraspecific matching matrix” in order to describe the simple year-class structure of the scallop along with the age distribution of slipper limpets stuck on scallop shells and forming the base of chains. Such a model can explore the dynamics of both populations at a secular time scale. This first part of work details the 0D-behavior of the populations, alone or together, on 1 m 2 benthic area. As far as the scallop is concerned, the fact that class 1 cannot recruit in dense populations until the death of old animals has freed some place induces a limit-cycle, with a 11 years period, and a large amplitude. On the contrary, in the case of the slipper limpet, because of the constant possibility for class 1 to recruit on the top of existing colonies, even if the bottom coverage is total, the population reaches a stable steady state abundance, without significant oscillations. Competition for space between the two species does not alter significantly the slipper limpet, whereas it lowers the mean abundance and alters (by damping and slowing down) the limit cycle of the scallop. [ABSTRACT FROM AUTHOR]

The invasive mollusk Crepidula fornicata, occurring in large amounts in bays along the French Northeastern Atlantic coasts, may have huge environmental effects in highly productive ecosystems where shellfish are exploited. The present study aims at determining the potential economic value of this marine species in terms of exploitable substances with high added value. Lipid content and phospholipid (PL) composition of this mollusk collected on the Bourgneuf Bay were studied through four seasons. Winter specimens contained the highest lipid levels (5.3% dry weight), including 69% of PLs. Phosphatidylcholine (PC) was the major PL class all year, accounting for 63.9% to 88.9% of total PLs. Consequently, the winter specimens were then investigated for PL fatty acids (FAs), and free sterols. Dimethylacetals (DMAs) were present (10.7% of PL FA + DMA mixture) revealing the occurrence of plasmalogens. More than forty FAs were identified, including 20:5n-3 (9.4%) and 22:6n-3 (7.3%) acids. Fourteen free sterols were present, including cholesterol at 31.3% of the sterol mixture and about 40% of phytosterols. These data on lipids of C. fornicata demonstrate their positive attributes for human nutrition and health. The PL mixture, rich in PC and polyunsaturated FAs, offers an interesting alternative source of high value-added marine lecithin.

Precise biodiversity mapping that can be compared over decades would greatly inform the discussion of climate change impacts on species richness and shifts in dominant benthic species. Buzzards Bay, Massachusetts, USA, has a long history of field studies documenting benthic community structure. This bioassessment compares 1955 benthic infaunal sampling results with 2011/2012 samples to determine whether there has been a compositional change. I also compared structural components including grain size and near-bottom temperatures. In addition, benthic temperature rise and fall was logged at 15-min intervals from May to October of consecutive years. There was an observed difference in the benthic compositional structure, substrate and temperature between the 1955 and 2011/2012 station conditions. The 1955 identification of Buzzards Bay as being nutrient poor and having a reported 20.5 °C benthic temperature maximum has changed. Coastal development has brought increased nutrient inputs, and the 2012 bottom temperature maximum was at least 4 °C greater. These conditions contribute to shifts in benthic species dominance, and the substrate itself has been transformed to shell reefs at the stations where the gastropod Crepidula fornicata proliferated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The invasive non-native gastropod Crepidula fornicata is well established in the Milford Haven Waterway (MHW) in south-west Wales, UK, since its first introduction to this ria in 1953. Whilst it reaches high densities within the MHW and has extended its range to the south of this ria, there has been very little northward expansion. Here, we report findings of a series of intertidal and subtidal surveys in 2009 and 2010 where we monitored the population density and the vertical distribution of C. fornicata at its northern range limit in Wales (the MHW). We also characterised the composition of the surface substrata of the seabed in the MHW to provide some insight into how the availability of certain settlement substrata may limit its distribution along the west coast of Britain. We found locally very dense aggregations (maximum 2748 ± 3859 individuals m, mean ± SD) in the shallow subtidal and low intertidal of the MHW. Subtidally, highest densities were found in areas of high gravel content (grain sizes ~16-256 mm), suggesting that the availability of this substrata type is beneficial for its establishment at a site. In the intertidal, on the other hand, high gravel content was indicative of low C. fornicata abundance, possibly because gravelly shores are an indicator of very exposed conditions that, at least in the intertidal, may result in high levels of early post-settlement mortality and low recruitment. C. fornicata was absent from the entrance of the MHW, possibly due to the lack of suitable settlement substrata. The presence of substantial populations in the MHW suggests that C. fornicata's population growth and potential expansion in Welsh coastal waters is not fully limited by prevailing environmental conditions in the region, but that other processes may affect its local distribution. [ABSTRACT FROM AUTHOR]

Many animals experience periods of feast or famine, which can have major consequences for growth, survival, and reproductive fitness. For animals with complex life histories, the question remains whether a major ontogenetic transition, such as metamorphosis, removes the legacy of early diet variability, or if early stressors persist into later stages. This study examined the effect of constant versus variable food availability and average food concentration during the larval stage on the performance of the marine gastropod Crepidula fornicata (L.) before and after metamorphosis. There was no detectable effect of variable food availability on larval growth, energy stores, survival, and metamorphic competence, or juvenile growth rate and survival. Instead, the average amount of food available during the larval period had the greatest impact on larval size and metamorphic competence. Surprisingly, there were no impacts of larval diet on growth or survival during the juvenile stage. Differences that originated during the larval stage were removed post-metamorphosis. These results suggest that some organisms may be resilient to variations in food availability and that not all early life experiences produce legacy effects. Heterogeneous environments, including variable food availability, should favor flexibility in the timing of ontogenetic transitions that allow individuals to be robust in later life stages. [ABSTRACT FROM AUTHOR]

The invasive mollusk Crepidula fornicata, occurring in large amounts in bays along the French Northeastern Atlantic coasts, may have huge environmental effects in highly productive ecosystems where shellfish are exploited. The present study aims at determining the potential economic value of this marine species in terms of exploitable substances with high added value. Lipid content and phospholipid (PL) composition of this mollusk collected on the Bourgneuf Bay were studied through four seasons. Winter specimens contained the highest lipid levels (5.3% dry weight), including 69% of PLs. Phosphatidylcholine (PC) was the major PL class all year, accounting for 63.9% to 88.9% of total PLs. Consequently, the winter specimens were then investigated for PL fatty acids (FAs), and free sterols. Dimethylacetals (DMAs) were present (10.7% of PL FA + DMA mixture) revealing the occurrence of plasmalogens. More than forty FAs were identified, including 20:5n-3 (9.4%) and 22:6n-3 (7.3%) acids. Fourteen free sterols were present, including cholesterol at 31.3% of the sterol mixture and about 40% of phytosterols. These data on lipids of C. fornicata demonstrate their positive attributes for human nutrition and health. The PL mixture, rich in PC and polyunsaturated FAs, offers an interesting alternative source of high value-added marine lecithin. [ABSTRACT FROM AUTHOR]

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., (© 2014 Wiley Periodicals, Inc.)