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1.
Dis Aquat Organ ; 148: 87-94, 2022 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-35297378

RESUMO

Several historic investigations have reported intranuclear virus infections of Mya arenaria soft-shell clams from the Atlantic coast of North America, but their descriptive details are limited. Among numerous multi-clam samples of Chesapeake Bay M. arenaria that were analyzed histopathologically during clam population surveys from 2000-2009, virus replication apparently caused extreme hypertrophy among the infected nuclei of gill epithelial cells. Infected cells were often abundant within the gill epithelia of affected clams, where their nuclear abnormalities suggested compromised genetic controls of critical cellular physiological functions. Infection prevalences were generally elevated, reaching 90% in 25% of samples. A grand mean prevalence of 67% resulted for all (69) M. arenaria samples of the decadal investigation, which included 1934 individual clams. Infected nuclei of gill epithelial cells were microscopically conspicuous by their extreme hypertrophic diameters of 10 µm or more and their prominent DNA-inclusion bodies. Cells with abnormal, hypertrophic nuclei were often abundant in the epithelia of M. arenaria gills. Transmission electron microscopy revealed abundant, replicating, icosahedral viral particles of 65-85 nm diameter within such hypertrophic nuclei. Viruses frequently occurred in paracrystalline nuclear arrays, showed granular internal contents, and had radial structures that suggested capsid surface ornamentation. Normal heterochromatin of infected nuclei appeared emarginated by dense central masses of replicating virions. Large, electron-dense DNA inclusion bodies routinely occurred at the internal margins of virus-infected nuclei. These may be virus replication centers based on their ultrastructural features and close proximity to replicated viral particles.


Assuntos
Mya , Animais , Baías , Vírus de DNA , Células Epiteliais , Brânquias
2.
Sci Total Environ ; 819: 152053, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34856270

RESUMO

Contaminants are ubiquitous in the environment, often reaching aquatic systems. Combinations of forestry use pesticides have been detected in both water and aquatic organism tissue samples in coastal systems. Yet, most toxicological studies focus on the effects of these pesticides individually, at high doses, and over acute time periods, which, while key for establishing toxicity and safe limits, are rarely environmentally realistic. We examined chronic (90 days) exposure by the soft-shell clam, Mya arenaria, to environmentally relevant concentrations of four pesticides registered for use in forestry (atrazine, 5 µg/L; hexazinone, 0.3 µg/L; indaziflam, 5 µg/L; and bifenthrin, 1.5 µg/g organic carbon (OC)). Pesticides were tested individually and in combination, except bifenthrin, which was tested only in combination with the other three. We measured shell growth and condition index every 30 days, as well as feeding rates, mortality, and chemical concentrations in tissue from a subset of clams at the end of the experiment to measure contaminant uptake. Indaziflam caused a high mortality rate (max. 36%), followed by atrazine (max. 27%), both individually as well as in combination with other pesticides. Additionally, indaziflam concentrations in tissue (61.70-152.56 ng/g) were higher than those of atrazine (26.48-48.56 ng/g), despite equal dosing concentrations, indicating higher tissue accumulation. Furthermore, clams exposed to indaziflam and hexazinone experienced reduced condition index and clearance rates individually and in combination with other compounds; however, the two combined did not result in significant mortality. These two compounds, even at environmentally relevant concentrations, affected a non-target organism and, in the case of the herbicide indaziflam, accumulated in clam tissue and appeared more toxic than other tested pesticides. These findings underscore the need for more comprehensive studies combining multiple compounds at relevant concentrations to understand their impacts on aquatic ecosystems.


Assuntos
Mya , Praguicidas , Poluentes Químicos da Água , Animais , Ecossistema , Agricultura Florestal , Praguicidas/análise , Praguicidas/toxicidade , Poluentes Químicos da Água/análise
3.
Vaccine ; 39(12): 1701-1707, 2021 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-33618945

RESUMO

Two type O commercial vaccines, the O1/Campos and O/Primorsky/2014 vaccines, were studied to evaluate the in vivo efficacy in pigs against heterologous virus challenge with the O/SKR/Jincheon/2014 virus (O/SEA/Mya-98 lineage) isolated in Korea in 2014. The in vivo challenge results indicated that both vaccines induced a high heterologous virus neutralization test (VNT) titer by a single injection and successfully protected specific pathogen-free (SPF) pigs from challenge infection. To determine the optimal vaccination age, a field trial with each vaccine was conducted with three one-shot-vaccinated groups that were injected at 8, 12, or 14 weeks of age and one two-shot-vaccinated group that was injected at 8 and 12 weeks of age in the pig farms. In these field trials, the improved serological performance at 20 and 24 weeks of age expected with vaccination at 12 or 14 weeks of age was not observed, although improved serological results were expected as the result of decreasing interference of maternally derived antibodies (MDAs), as MDAs waned with age. In addition, delayed vaccination resulted in MDA depletion at 14 weeks of age. Therefore, the optimal age for primary vaccination with two different formulated vaccines was 8 weeks old in pigs, considering that MDAs could provide a protective immunity against foot-and-mouth disease (FMD) infection. Prolonged significantly higher VNT titers of immunized pigs were demonstrated in the two-shot-vaccinated groups. In total, the effectiveness of the two vaccines was demonstrated through efficacy tests and field trials in pigs.


Assuntos
Vírus da Febre Aftosa , Febre Aftosa , Mya , Doenças dos Suínos , Vacinas Virais , Animais , Anticorpos Antivirais , Extremo Oriente , Febre Aftosa/prevenção & controle , República da Coreia , Suínos , Doenças dos Suínos/prevenção & controle , Vacinação
4.
J Exp Biol ; 224(Pt 4)2021 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-33436367

RESUMO

Estuarine and coastal benthic organisms often experience fluctuations in oxygen levels that can negatively impact their mitochondrial function and aerobic metabolism. To study these impacts, we exposed a common sediment-dwelling bivalve, the soft-shell clam Mya arenaria, for 21 days to chronic hypoxia (P O2  âˆ¼4.1 kPa), cyclic hypoxia (P O2  âˆ¼12.7-1.9 kPa, mean 5.7 kPa) or normoxia (P O2  âˆ¼21.1 kPa). pH was manipulated to mimic the covariation in CO2/pH and oxygen levels in coastal hypoxic zones. Mitochondrial respiration, including proton leak, the capacity for oxidative phosphorylation (OXPHOS), the maximum activity of the electron transport system (ETS), reactive oxygen species (ROS) production, and activity and oxygen affinity of cytochrome c oxidase (CCO) were assessed. Acclimation to constant hypoxia did not affect the studied mitochondrial traits except for a modest decrease in the OXPHOS coupling efficiency. Cyclic hypoxia had no effect on OXPHOS or ETS capacity, but increased proton leak and lowered mitochondrial OXPHOS coupling efficiency. Furthermore, mitochondria of clams acclimated to cyclic hypoxia had higher rates of ROS generation compared with the clams acclimated to normoxia or chronic hypoxia. CCO activity was upregulated under cyclic hypoxia, but oxygen affinity of CCO did not change. These findings indicate that long-term cyclic hypoxia has a stronger impact on the mitochondria of M. arenaria than chronic hypoxia and might lead to impaired ATP synthesis, higher costs of mitochondrial maintenance and oxidative stress. These changes might negatively affect populations of M. arenaria in the coastal Baltic Sea under increasing hypoxia pressure.


Assuntos
Mya , Animais , Metabolismo Energético , Mitocôndrias/metabolismo , Oxigênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo
5.
PLoS One ; 15(10): e0241116, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33104744

RESUMO

Non-indigenous species are often identified as threats to native species and communities. Yet, the mechanisms that enable many of these invaders to thrive and alter their newly invaded habitats are still not fully understood. This applies to habitats such as widespread sedimentary shorelines characterized by the presence of scattered biogenic clumps of blue mussels (Mytilus edulis) structurally more complex than bare sediments. In Atlantic Canada, some of these shorelines are numerically dominated by native mud crabs (Dyspanopeus sayi) but have been gradually invaded by the European green crab (Carcinus maenas). This study describes between-habitat (mussel clump vs. bare sediment) differences in density and diversity of invertebrates. It also tests the impact of juvenile green crabs in comparison to native mud crabs using two approaches: First, measuring habitat-related differences in these crabs' feeding rates on a common prey (soft-shell clams, Mya arenaria). Second, measuring their influence on invertebrate communities associated with mussel clumps. The results show that mussel clumps hold higher invertebrate density and diversity than surrounding sedimentary bottoms. In the laboratory, the feeding rates of native mud crabs were dependent on the type of habitat (sand flat > mussel clump), whereas those of green crabs were significantly higher and unrelated to the habitat in which predation occurred. In field experiments, juvenile green crabs were also the only predators that changed community structure in the mussel clump habitat. These results indicate that green crabs can cause a significant impact on native species and communities. Moreover, they suggest that the ability of this species to overcome the refuge provided by complex biogenic habitats for prey may represent an unexplored mechanism to explain this invader's expansion here and elsewhere.


Assuntos
Braquiúros , Cadeia Alimentar , Mya , Mytilus edulis , Animais , Canadá , Espécies Introduzidas , Comportamento Predatório
6.
Int J Biol Macromol ; 165(Pt A): 1219-1228, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33038395

RESUMO

We report herein new nanofibers prepared from fish scale gelatine (FSG), modified polylactide (MPLA), and a natural antibacterial agent of freshwater clam (Corbicula fluminea Estefanía) shell powder (FCSP). A preparation of FSG from Mullet scales is also described. To improve the biocompatibility and antibacterial activity of the non-woven nanofibers, MPLA/FCSP was added to enhance their antibacterial properties. FSG was then combined with MPLA/FCSP using an electrospinning technique to improve the biocompatibility of the as-fabricated 100-500-nm-diameter non-woven MPLA/FCSP/FSG nanofibers. The resulting tensile properties and morphological characteristics indicated enhanced adhesion among FSG, FCSP, and MPLA in the MPLA/FCSP/FSG nanofibers, as well as improved water resistance and tensile strength, compared with the PLA/FSG nanofibers. MTT assay, cell-cycle, and apoptosis analyses showed that both PLA/FSG and MPLA/FCSP/FSG nanofibers had good biocompatibility. Increasing the FSG content in PLA/FSG and MPLA/FCSP/FSG nanofibers enhanced cell proliferation and free-radical scavenging ability, but did not affect cell viability. Quantitative analysis of bacteria inhibition revealed that FCSP imparts antibacterial activity.


Assuntos
Gelatina/química , Nanofibras/química , Poliésteres/química , Animais , Corbicula/química , Corbicula/microbiologia , Peixes/microbiologia , Água Doce/química , Mya/química , Mya/microbiologia , Nanofibras/microbiologia , Poliésteres/farmacologia
7.
Artigo em Inglês | MEDLINE | ID: mdl-32758703

RESUMO

Benthic organisms are subject to prolonged seasonal food limitation in the temperate shallow coastal waters that can cause energetic stress and affect their performance. Sediment-dwelling marine bivalves cope with prolonged food limitation by adjusting different physiological processes that might cause trade-offs between maintenance and other fitness-related functions. We investigated the effects of prolonged (42 days) food deprivation on bioenergetics, burrowing performance and amino acid profiles in a common marine bivalve, Mya arenaria collected in winter and spring. Food limitation of >15 days decreased respiration of the clams by 80%. Total tissue energy content was higher in spring-collected clams (reflecting higher lipid content) than in their winter counterparts. Prolonged food deprivation decreased the tissue energy content of clams, especially in winter. The levels of free amino acids transiently increased during the early phase of food deprivation possibly reflecting suppression of the protein synthesis or enhanced protein degradation. The levels of amino acids considered essential for bivalves were more tightly conserved than those of non-essential amino acids during starvation. The burrowing capacity of clams was negatively affected by food deprivation so that the time required for a burial cycle increased by 35-50% after 22-42 days of starvation. During the early phase of starvation, clams preferentially used lipids as fuel for burrowing, whereas carbohydrates were used at the later phase. These findings suggest that although M. arenaria can withstand prolonged food deprivation by lowering their basal maintenance costs and switching their fuel usage, their ecological functions (e.g. bioturbation and the energy transferable to the next trophic level) could be negatively impacted by starvation.


Assuntos
Metabolismo Energético , Privação de Alimentos , Mya/metabolismo , Animais , Comportamento Animal , Estações do Ano
8.
Genome Biol Evol ; 12(10): 1681-1693, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32653903

RESUMO

Apoptosis is a fundamental feature of multicellular animals and is best understood in mammals, flies, and nematodes, with the invertebrate models being thought to represent a condition of ancestral simplicity. However, the existence of a leukemia-like cancer in the softshell clam Mya arenaria provides an opportunity to re-evaluate the evolution of the genetic machinery of apoptosis. Here, we report the whole-genome sequence for M. arenaria which we leverage with existing data to test evolutionary hypotheses on the origins of apoptosis in animals. We show that the ancestral bilaterian p53 locus, a master regulator of apoptosis, possessed a complex domain structure, in contrast to that of extant ecdysozoan p53s. Further, ecdysozoan taxa, but not chordates or lophotrochozoans like M. arenaria, show a widespread reduction in apoptosis gene copy number. Finally, phylogenetic exploration of apoptosis gene copy number reveals a striking linkage with p53 domain complexity across species. Our results challenge the current understanding of the evolution of apoptosis and highlight the ancestral complexity of the bilaterian apoptotic tool kit and its subsequent dismantlement during the ecdysozoan radiation.


Assuntos
Apoptose/genética , Genes p53 , Genoma , Mya/genética , Filogenia , Animais
9.
Genes (Basel) ; 11(3)2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32168796

RESUMO

The soft-shell clam Mya arenaria is one of the most ancient invaders of European coasts and is present in many coastal ecosystems, yet little is known about its genetic structure in Europe. We collected 266 samples spanning a latitudinal cline from the Mediterranean to the North Sea and genotyped them at 12 microsatellite loci. In parallel, geometric morphometric analysis of shell outlines was used to test for associations between shell shape, latitude and genotype, and for a selection of shells we measured the thickness and organic content of the granular prismatic (PR), the crossed-lamellar (CL) and the complex crossed-lamellar (CCL) layers. Strong population structure was detected, with Bayesian cluster analysis identifying four groups located in the Mediterranean, Celtic Sea, along the continental coast of the North Sea and in Scotland. Multivariate analysis of shell shape uncovered a significant effect of collection site but no associations with any other variables. Shell thickness did not vary significantly with either latitude or genotype, although PR thickness and calcification were positively associated with latitude, while CCL thickness showed a negative association. Our study provides new insights into the population structure of this species and sheds light on factors influencing shell shape, thickness and microstructure.


Assuntos
Ecossistema , Genética Populacional , Mya/anatomia & histologia , Mya/genética , Animais , Europa (Continente) , Genótipo , Hemócitos , Repetições de Microssatélites/genética , Mya/química , Mar do Norte , Escócia
10.
PLoS One ; 14(10): e0224551, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31671146

RESUMO

Teredinid bivalves, commonly referred to as shipworms, are known for their propensity to inhabit, bioerode, and digest woody substrates across a range of brackish and fully marine settings. Shipworm body fossils and/or their borings, which are most allied with the ichnotaxon Teredolites longissimus, are found in wood preserved in sedimentary sequences ranging in age from Early Cretaceous to Recent and traditionally they have been regarded as evidence of marginal marine or marine depositional environments. Recent studies associated with the Philippine Mollusk Symbiont International Collaboration Biodiversity Group (PMS-ICBG) expedition on the island of Bohol, Philippines, have identified a new shipworm taxon (Lithoredo abatanica) that is responsible for macrobioerosion of a moderately indurated Neogene foraminiferal packstone cropping out along a freshwater reach of the Abatan River. In the process of drilling into and ingesting the limestone, these shipworms produce elongate borings that expand in diameter very gradually toward distal termini, exhibit sinuous or highly contorted axes and circular transverse outlines, and are lined along most of their length by a calcite tube. Given their strong resemblance to T. longissimus produced in wood but their unusual occurrence in a lithic substrate, these shipworm borings can be regarded as incipient Gastrochaenolites or, alternatively, as Apectoichnus. The alternate names reflect that the borings provide a testbed for ideas of the appropriateness of substrate as an ichnotaxobasis. The discovery of previously unrecognized shipworm borings in lithic substrates and the co-occurrence of another shipworm (Nausitora) in submerged logs in the same freshwater setting have implications for interpreting depositional conditions based on fossil teredinids or their ichnofossils. Of equal significance, the Abatan River study demonstrates that macrobioerosion in freshwater systems may be just as important as it is in marine systems with regard to habitat creation and landscape development. L. abatanica serve as ecosystems engineers in the sense that networks of their abandoned borings provide habitats for a variety of nestling invertebrates, and associated bioerosion undoubtedly enhances rates of mechanical and chemical degradation, thus influencing the Abatan River profile.


Assuntos
Bivalves/classificação , Mya/classificação , Animais , Biodiversidade , Bivalves/metabolismo , Ecossistema , Fósseis , Água Doce , Filipinas , Filogenia , Rios , Simbiose
11.
PLoS One ; 14(2): e0211815, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30730941

RESUMO

Climate change is impacting environmental conditions, especially with respect to temperature and ice cover in high latitude regions. Predictive models and risk assessment are key tools for understanding potential changes associated with such impacts on coastal regions. In this study relative ecological risk assessment was done for future potential introductions of three species in the Canadian Arctic: periwinkle Littorina littorea, soft shell clam Mya arenaria and red king crab Paralithodes camtschaticus. These species occur in locations connected to Canadian Arctic ports through shipping and have the potential to be introduced via ballast water discharge. The methodology proposed in this study is unique in the sense that it considers not only ballast water origin, but also the distribution of the species being assessed and the sensitivity of the receiving habitat. It combines detailed information (ballast water source of each tank, transit time, time of the year when the water is released, environmental suitability of receiving habitat, impact, and habitat sensitivity) in order to assess ecological risk. Through the use of this approach it is highlighted that domestic discharge events pose a higher relative overall risk on a vessel-specific and cumulative annual bases than international discharges. The main ports of Deception Bay and Churchill were classified as being at moderate to high relative risk for L. littorea and M. arenaria, especially from domestic vessels, while relative overall risk for P. camtschaticus was low for international vessels and null for domestic vessels due to few ships transiting from its range of distribution to Canadian Arctic ports. This work can serve as an approach to help build a list of potential high risk species-a "grey" watch list-for the Canadian Arctic, and provides useful information for consideration in future decision making actions such as the identification of high risk pathways, species and ports.


Assuntos
Anomuros/fisiologia , Organismos Aquáticos/fisiologia , Gastrópodes/fisiologia , Espécies Introduzidas , Modelos Biológicos , Mya/fisiologia , Animais , Regiões Árticas , Canadá , Medição de Risco
12.
Mar Environ Res ; 143: 101-110, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30477876

RESUMO

To estimate the contribution of a Mya arenaria population to total oxygen utilization (TOU) at different temperatures, the respiration rate of M. arenaria was measured for a full size range at 5 and 15 °C. In this study we measured respiration rates in a closed system while the clams were burrowed in sandy sediment, resembling their natural habitat. Rates were measured over a sufficient time span (24 h) to average varying activity phases during the measurements. We calculated a size-dependent respiration rate for M. arenaria and its variation with temperature. Temperature strongly affects the total population respiration and the contribution of different size classes to respiration of the total M. arenaria population. M. arenaria was estimated to contribute up to 70% to the total oxygen utilization of benthic communities analyzed in this study very much depending on the size distribution of the bivalve population present. Given a specific size distribution, smaller individuals had a stronger influence on the total oxygen utilization at colder temperature, while the influence of larger individuals grew with warmer temperature. Even though sizes contribute differently, a significant relation between abundance and respiration could be drawn in most cases analyzed. However, this relation should not be used as a general rule, but when estimating a population's metabolism the size distribution within that population has to be regarded.


Assuntos
Sedimentos Geológicos/química , Mya , Animais , Biologia Marinha , Mya/anatomia & histologia , Mya/fisiologia , Oxigênio , Consumo de Oxigênio , Respiração , Temperatura
13.
PLoS One ; 13(10): e0205162, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30289889

RESUMO

In Chesapeake Bay, the soft-shell clam Mya arenaria (thin-shelled, deep-burrowing) exhibits population declines when predators are active, and it persists at low densities. In contrast, the hard clam Mercenaria mercenaria (thick-shelled, shallow-burrowing) has a stable population and age distribution. We examined the potential for habitat and predators to control densities and distributions of bivalves in a field caging experiment (Mya only) and laboratory mesocosm experiments (both species). In the field, clams exposed to predators experienced 76.3% greater mortality as compared to caged individuals, and blue crabs were likely responsible for most of the mortality of juvenile Mya. In mesocosm experiments, Mya had lower survival in sand and seagrass than in shell hash or oyster shell habitats. However, crabs often missed one or more prey items in seagrass, shell, and oyster shell habitats. Predator search times and encounter rates declined when prey were at low densities, likely due to the added cost of inefficient foraging; however, this effect was more pronounced for Mya than for Mercenaria. Mercenaria had higher survival than Mya in mesocosm experiments, likely because predators feeding on Mercenaria spent less time foraging than those feeding on Mya. Mya may retain a low-density refuge from predation even with the loss of structurally complex habitats, though a loss of habitat refuge may result in clam densities that are not sustainable. A better understanding of density-dependent predator-prey interactions is necessary to prevent loss of food-web integrity and to conserve marine resources.


Assuntos
Baías , Braquiúros , Ecossistema , Mercenaria , Mya , Comportamento Predatório , Distribuição Animal , Animais , Raios Infravermelhos , Densidade Demográfica , Tecnologia de Sensoriamento Remoto , Rios , Virginia
14.
Mar Pollut Bull ; 135: 165-175, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30301026

RESUMO

Cues that drive bivalve settlement and abundance in sediments are not well understood, but recent reports suggest that sediment carbonate chemistry may influence bivalve abundance. In 2013, we conducted field experiments to assess the relationship between porewater sediment carbonate chemistry (pH, alkalinity (At), dissolved inorganic carbon (DIC)), grain size, and bivalve abundance throughout the July-September settlement period at two sites in Long Island Sound (LIS), CT. Two dominate bivalves species were present during the study period Mya arenaria and Nucula spp. Akaike's linear information criterion models, indicated 29% of the total community abundance was predicted by grain size, salinity, and pH. When using 2 weeks of data during the period of peak bivalve settlement, pH and phosphate concentrations accounted 44% of total bivalve community composition and 71% of Nucula spp. abundance with pH, phosphate, and silica. These results suggest that sediment carbonate chemistry may influence bivalve abundance in LIS.


Assuntos
Bivalves/fisiologia , Sedimentos Geológicos/química , Animais , Carbono/análise , Carbonatos/análise , Connecticut , Concentração de Íons de Hidrogênio , Mya/fisiologia , Salinidade , Água do Mar/química
15.
Aquat Toxicol ; 202: 196-206, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30075308

RESUMO

Blooms of Alexandrium spp., the causative agent of paralytic shellfish poisoning (PSP), recur with varying frequency and intensity on the Northwest Atlantic coast of North America, from New York, USA, to northern Canadian waters. Along this latitudinal range blooms co-occur with abundant, intertidal populations of softshell clams, Mya arenaria. Prior work identified a naturally-occurring genetic mutation in Domain II α-subunit of the clams' voltage-gated sodium channels (NaV), which significantly reduces the binding affinity of the paralytic shellfish toxin, saxitoxin (STX). This mutation provides clams with resistance to the deleterious effects of STX, allowing them to continue feeding during Alexandrium spp. blooms and attain very high tissue toxicities. This study used genetic sequencing of the NaV mutation locus in clams from four coastal regions of the Bay of Fundy-Gulf of Maine and the mid-Atlantic to determine the percentage of clams in each region that possess the resistant NaV mutation. The genotype composition was related to the occurrence and magnitude of PSP outbreaks based on shellfish toxicity, primarily that of mussels, Mytilus edulis, used as a proxy for the prevalence and severity of Alexandrium blooms in each region. As hypothesized, the proportion of clams bearing the resistant mutation generally matched up well with the historical incidence and intensity of Alexandrium spp. blooms. The highest percentage of homozygote resistant clams (RR = 70.0%), and the lowest percentage of sensitive clams (SS = 4.5%) were found in eastern Gulf of Maine populations. Exceptions at a few sites where anomalously high numbers of M. arenaria with the resistant mutation were found despite the absence of blooms, may be attributable to larval gene flow. There was no evidence that Alexandrium blooms occurring in Northport Harbor, Long Island, have resulted in a shift in genotypic composition of the local clam population, presumably due to their low cell toxicity. Seasonal mismatch of highly vulnerable M. arenaria postset with toxic blooms at this latitude may also partly explain this result. This study provides strong supporting evidence that Alexandrium blooms can select for resistance to PSP-toxins in M. arenaria populations and proposes a mechanism for the persistence of the sensitive allele throughout the region. Implications for clam aquaculture (seeding) efforts, as well as for shellfish toxicity monitoring are discussed.


Assuntos
Mya/efeitos dos fármacos , Saxitoxina/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Genótipo , Larva/efeitos dos fármacos , Larva/genética , Mutação , Mya/genética , Mya/crescimento & desenvolvimento , América do Norte , Intoxicação por Frutos do Mar , Canais de Sódio Disparados por Voltagem/genética
16.
Tissue Cell ; 52: 101-107, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29857818

RESUMO

In this study we designed a composite biomaterial based on a high viscosity soft propolis extract (70% propolis) and shell clam, with antiseptic and osteoinductive qualities, that can be used in dentistry, orthopedics and other areas where hard tissue regeneration is needed. We assessed it in interaction with stabilized human cells isolated from dental papilla of wisdom teeth (D1MSCs). We performed detailed characterization of the obtained material by Scanning Electronic Microscopy (SEM), X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR) techniques. SEM investigation revealed the roughness and porosity of the shell, which acted like a scaffold, as it allowed cells to penetrate the pores, proliferate on the surface, spread and grow in the depressions provided by the substrate. in vitro cell viability, proliferation and differentiation assays showed that the newly obtain biomaterial presented low toxicity on D1MSCs and determined the development of numerous osteogenic nodules that were in a higher number even than in the specific induction medium. Our results demonstrated that the shell-propolis based biomaterial promoted and sustained human stem cells attachment, proliferation and differentiation, presenting an important osteoinductive effect essential for mineralized tissue reparation process.


Assuntos
Materiais Biocompatíveis/química , Mya , Própole , Engenharia Tecidual/métodos , Tecidos Suporte/química , Animais , Diferenciação Celular , Proliferação de Células , Humanos , Osteogênese , Células-Tronco/citologia
17.
Cell Stress Chaperones ; 23(5): 1003-1017, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29754331

RESUMO

Acclimation, via phenotypic flexibility, is a potential means for a fast response to climate change. Understanding the molecular mechanisms underpinning phenotypic flexibility can provide a fine-scale cellular understanding of how organisms acclimate. In the last 30 years, Mya truncata populations around the UK have faced an average increase in sea surface temperature of 0.7 °C and further warming of between 1.5 and 4 °C, in all marine regions adjacent to the UK, is predicted by the end of the century. Hence, data are required on the ability of M. truncata to acclimate to physiological stresses, and most notably, chronic increases in temperature. Animals in the present study were exposed to chronic heat-stress for 2 months prior to shell damage and subsequently, only 3, out of 20 damaged individuals, were able to repair their shells within 2 weeks. Differentially expressed genes (between control and damaged animals) were functionally enriched with processes relating to cellular stress, the immune response and biomineralisation. Comparative transcriptomics highlighted genes, and more broadly molecular mechanisms, that are likely to be pivotal in this lack of acclimation. This study demonstrates that discovery-led transcriptomic profiling of animals during stress-response experiments can shed light on the complexity of biological processes and changes within organisms that can be more difficult to detect at higher levels of biological organisation.


Assuntos
Exoesqueleto , Resposta ao Choque Térmico/genética , Mya/genética , Aclimatação , Exoesqueleto/anatomia & histologia , Animais , Proteínas de Choque Térmico/biossíntese , Mya/anatomia & histologia , Mya/metabolismo , Mapeamento de Interação de Proteínas , Transcriptoma
18.
J Exp Biol ; 221(Pt 4)2018 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-29361598

RESUMO

Bioturbation of sediments by burrowing organisms plays a key role in the functioning of coastal ecosystems. Burrowing is considered an energetically expensive activity, yet the energy costs of burrowing and the potential impacts of multiple stressors (such as salinity stress and wave action) on bioenergetics and burrowing performance of marine bioturbators are not well understood. We investigated the effects of mechanical disturbance and salinity stress on the burrowing behavior, aerobic capacity and energy expense of digging in a common marine bioturbator, the soft-shell clam Mya arenaria from the Baltic Sea (control salinity 15). Mya arenaria showed large individual variability in the burrowing efficiency, with an average of ∼7% of the body energy reserves used per burial. Clams with higher mitochondrial capacity and lower energy expenditure per burial showed higher endurance. Acclimation for 3-4 weeks to low (5) or fluctuating (5-15) salinity reduced the burrowing speed and the number of times the clams can rebury but did not affect the mitochondrial capacity of the whole body or the gill. Acclimation to the fluctuating salinity shifted the predominant fuel use for burrowing from proteins to lipids. Our data indicate that the reduced burrowing performance of clams under the salinity stress is not due to the limitations of energy availability or aerobic capacity but must involve other mechanisms (such as impaired muscle performance). The reduction in the burrowing capacity of clams due to salinity stress may have important implications for survival, activity and ecological functions of the clams in shallow coastal ecosystems.


Assuntos
Metabolismo Energético , Mya/fisiologia , Estresse Salino , Animais , Fenômenos Biomecânicos , Locomoção , Distribuição Aleatória
19.
J R Soc Interface ; 15(138)2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29367238

RESUMO

We present some of the few suspension-feeding measurements and to our knowledge the first velocity-field measurements for early post-settlement juvenile bivalve clams. We verify and extend our experimental results with numerical simulations. For 1.8-2.8 mm shell length Mya arenaria clams, pumping rates ranged 0.03-0.22 µl s-1, inhalant siphon Reynolds numbers (Re) ranged 0.16-0.79 and mean inhalant velocities ranged 0.8-3.2 mm s-1 Owing to the low Re at which they pump and the small diameters of their siphons, juvenile clams are subject to unique hydrodynamic challenges, including high siphon resistance and susceptibility to refiltration. At least three features of juvenile clam siphons differentiate them from those of adults-shorter inhalant siphon length, a more rapid increase in inhalant siphon diameter with shell length, and the presence of a prominent exhalant siphon extension. These features are probably adaptations to the challenges of suspension feeding at low Re.


Assuntos
Comportamento Alimentar/fisiologia , Modelos Biológicos , Mya/anatomia & histologia , Mya/fisiologia , Animais , Hidrodinâmica
20.
Mar Genomics ; 27: 69-74, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27068305

RESUMO

Mya truncata, a soft shell clam, is presented as a new model to study biomineralization through a proteomics approach. In this study, the shell and mantle tissue were analysed in order to retrieve knowledge about the secretion of shell matrix proteins (SMPs). Out of 67 and 127 shell and mantle proteins respectively, 16 were found in both shell and mantle. Bioinformatic analysis of SMP sequences for domain prediction revealed the presence of several new domains such as fucolectin tachylectin-4 pentraxin-1 (FTP), scavenger receptor, alpha-2-macroglobulin (α2 M), lipocalin and myosin tail along with previously reported SMP domains such as chitinase, carbonic anhydrase, tyrosinase, sushi, and chitin binding. Interestingly, these newly predicted domains are attributed with molecular functions other than biomineralization. These findings suggest that shells may not only act as protective armour from predatory action, but could also actively be related to other functions such as immunity. In this context, the roles of SMPs in biomineralization need to be looked in a new perspective.


Assuntos
Exoesqueleto/crescimento & desenvolvimento , Mya/genética , Proteoma , Exoesqueleto/metabolismo , Animais , Calcificação Fisiológica , Mya/crescimento & desenvolvimento , Mya/metabolismo , Proteômica , Escócia
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