Expression and functional analysis of Fushi Tarazu transcription factor 1 (FTZ-F1) in the regulation of steroid hormones during the gonad development of Fujian Oyster, Crassostrea angulata.

Crassostrea angulata, a major shellfish cultivated in Southern China, has experienced a notable surge in commercial value in recent years. Understanding the molecular mechanisms governing their reproductive processes holds significant implications for advancing aquaculture practices. In this study, we cloned the orphan nuclear receptor gene, Fushi Tarazu transcription factor 1 (FTZ-F1), of C. angulata and investigated its functional role in the gonadal development. The full-length cDNA of FTZ-F1 spans 2357 bp and encodes a protein sequence of 530 amino acids. Notably, the amino acid sequence of FTZ-F1 in C. angulata shares remarkable similarity with its homologues in other species, particularly in the DNA-binding region (>90%) and ligand-binding region (>44%). In C. angulata, the highest expression level of FTZ-F1 was observed in the ovary, exhibiting more than a 200-fold increase during the maturation stage compared to the initiation stage (P < 0.001). Specifically, FTZ-F1 was mainly expressed in the follicular cells surrounding the oocytes of C. angulata. Upon inhibiting FTZ-F1 gene expression in C. angulata through RNA interference (RNAi), a substantial reduction in the expression of genes involved in the synthesis of sex steroids in the gonads, including 3ß-HSD, Cyp17, and follistatin, was observed. In addition, estradiol (E2) and testosterone (T) levels also showed a decrease upon FTZ-F1 silencing, resulting in a delayed gonadal development. These results indicate that FTZ-F1 acts as a steroidogenic factor, participating in the synthesis and regulation of steroid hormones and thus playing an important role in the reproductive and endocrine systems within oysters.

Growth and survival of the native oyster Crassostrea gasar cultured under different stocking densities in two grow-out systems in tropical climate / [Crescimento e sobrevivência da ostra nativa Crassostrea gasar cultivada em diferentes densidades em dois sistemas em clima tropical]

Survival and growth of the native oyster Crassostrea gasar along the juvenile and adult phases were evaluated in three different stocking densities [low (D), medium (2D) and high (3D)] and in two grow-out systems (fixed and floating system). The fixed system consisted of a rack made with PVC, fixed from the bottom with wood sticks. The floating system consisted of floating bags suspended by a rack made with PVC and maintained submerged from the seawater surface by eight floats. Survival and shell height of oysters cultured after 30, 60 and 90 days were registered in each phase and in each grow-out system. Results showed that the grow-out system did not affect survival and growth of C. gasar in the juvenile and adult phases. The tested densities affected the survival of oysters cultured over time in both phases but did not affect oyster growth. At times analyzed, it was observed positive growth in juvenile oysters grow after 90 days of culture. However, in the adult phase, no growth was observed after 90 days of culture. Oyster yield was higher in the density 3D, in both juvenile and adult phases. These findings contributed to the development of the oyster C. gasar culture.(AU)

A sobrevivência e o crescimento da ostra nativa Crassostrea gasar nas fases juvenil e adulta foram avaliados sob três diferentes densidades de estocagem [baixa (D), média (2D) e alta (3D)] e dois sistemas de engorda (fixo e flutuante). O sistema fixo consistiu em uma mesa de PVC, fixada na parte inferior com varas de madeira. O sistema flutuante consistiu em travesseiros flutuantes suspensos por uma mesa de PVC e mantidas submersas da superfície da água do mar por oito flutuadores. Registraram-se sobrevivência e altura da concha de ostras cultivadas após 30, 60 e 90 dias, em cada fase (juvenil e adulta) e em cada sistema (fixo e flutuante). Os resultados mostraram que o sistema de engorda não afetou a sobrevivência e o crescimento de C. gasar nas fases juvenil e adulta. As densidades testadas afetaram a sobrevivência das ostras ao longo do tempo, em ambas as fases, mas não afetaram o crescimento em altura. Nos tempos analisados, ostras juvenis apresentaram crescimento após 90 dias de cultivo. Porém, na fase adulta, não foi observado crescimento após 90 dias de cultivo. A produção de ostras, foi maior na densidade 3D, nas fases juvenil e adulta. Os presentes achados contribuíram para o desenvolvimento do cultivo da ostra C. gasar.(AU)

Identification, characterization, and expression profiles of insulin-like peptides suggest their critical roles in growth regulation of the Pacific oyster, Crassostrea gigas.

The insulin/insulin-like growth factor signaling (IIS) pathway is well-known in regulation of cell growth and proliferation in vertebrates, while its role in invertebrates such as mollusks remains largely unknown. In this study, we performed an extensive multi-omics data mining and identified four insulin-like peptide genes, including ILP, MIRP3, MIRP3-like and ILP7, in the Pacific oyster, Crassostrea gigas. Their potential roles in growth regulation were further investigated using the selectively bred fast-growing C. gigas variety "Haida No.1". Expression profiling and in situ hybridization of these insulin-like peptides suggested their distinct tissue-specific expression pattern, with dominant expression in the neural enrichment tissues such as labial palp, visceral ganglia, adductor muscle, and digestive gland. The expressions of insulin-like peptides were significantly altered by food abundance in a gene-specific fashion. The expression of ILP was reduced during fasting and increased after re-feeding, the expressions of MIRP3 and ILP7 were generally induced during fasting and down-regulated after re-feeding, while the expression of MIRP3-like was firstly up-regulated and then down-regulated during the fasting and re-feeding process. Furthermore, the expressions of all four insulin-like peptide genes were significantly suppressed at low temperature, in accordance with the growth inhibition. These results indicated that all four insulin-like peptides would play critical but different roles in regulation of growth in the oysters. This work provides valuable information for further investigation on growth regulation mechanism in mollusks and molecular assisted breeding of growth with other production traits in the Pacific oyster.

A functional m6 A-RNA methylation pathway in the oyster Crassostrea gigas assumes epitranscriptomic regulation of lophotrochozoan development.

N6 -methyladenosine (m6 A) is a prevalent epitranscriptomic mark in eukaryotic RNA, with crucial roles for mammalian and ecdysozoan development. Indeed, m6 A-RNA and the related protein machinery are important for splicing, translation, maternal-to-zygotic transition and cell differentiation. However, to date, the presence of an m6 A-RNA pathway remains unknown in more distant animals, questioning the evolution and significance of the epitranscriptomic regulation. Therefore, we investigated the m6 A-RNA pathway in the oyster Crassostrea gigas, a lophotrochozoan model whose development was demonstrated under strong epigenetic influence. Using mass spectrometry and dot blot assays, we demonstrated that m6 A-RNA is actually present in the oyster and displays variations throughout early oyster development, with the lowest levels at the end of cleavage. In parallel, by in silico analyses, we were able to characterize at the molecular level a complete and conserved putative m6 A machinery. The expression levels of the identified putative m6 A writers, erasers and readers were strongly regulated across oyster development. Finally, RNA pull-down coupled to LC-MS/MS allowed us to prove the actual presence of readers able to bind m6 A-RNA and exhibiting specific developmental patterns. Altogether, our results demonstrate the conservation of a complete m6 A-RNA pathway in the oyster and strongly suggest its implication in early developmental processes including MZT. This first demonstration and characterization of an epitranscriptomic regulation in a lophotrochozoan model, potentially involved in the embryogenesis, bring new insights into our understanding of developmental epigenetic processes and their evolution.

Probiotic Bacterium and Microalga Interaction on Rearing Kumamoto Oyster Crassostrea sikamea Spat.

This study assessed in vitro interaction between Bacillus bacteria and microalgae and their posterior in vivo effect on rearing Kumamoto oyster Crassostrea sikamea. The probiotic strains Bacillus licheniformis (MAt32), B. subtilis (MAt43) and B. subtilis (GAtB1) were individually inoculated in triplicate into 250 mL flasks containing 1 × 104 colony forming units (CFU) mL-1 of bacteria and 4.5 × 104 cell mL-1 of microalgae (Isochrysis galbana or Chaetoceros calcitrans) to evaluate their growth during a 7-day culture. Single cultures of microalgae or bacilli served as control. Additionally, C. sikamea spat was treated for 28 days with four single/combined bacillus treatments in triplicate at a concentration of 1 × 106 CFU mL-1 as follows: (a) control, without treatments; (b) combination of two antibiotics (10 mg L-1); (c) B. licheniformis; (d) B. subtilis; (e) B. subtilis subtilis and (f) mixed bacilli. The results showed a significantly (P < 0.05) increased growth of Bacillus strains co-cultured with microalgae, while the growth of I. galbana co-cultured with bacteria was not reduced significantly (P > 0.05) compared with the control group. C. sikamea spat treated with Bacillus showed significantly (P < 0.05) higher growth and survival than the control group. In this study, C. calcitrans microalgae were susceptible to the presence of probiotic bacteria. Nonetheless, this reduction in microalgal growth observed in vitro increased growth and survival of C. sikamea spat exposed to probiotic bacteria when compared to spat without probiotics.

Growth and antioxidant response of juvenile oysters Crassostrea sikamea and Crassostrea corteziensis treated with Streptomyces strains / Crescimento e resposta oxidative de ostras jovens Crassostrea sikamea e Crassostrea corteziensis tratadas com cultura Streptomyces

The effect of three Streptomyces strains (N7, RL8 and V4) and a mixture of Bacillus (BMix) on the growth (Weight, Size) and superoxide dismutase activity (SOD) in hatchery-reared juvenile oysters Crassostrea corteziensis and Crassostrea sikamea was investigated to determine their probiotic potential. Microorganisms were added to culture water at 1×106 CFU/ml once a day during 30 days and all oysters fed daily a microalgae mix. Juveniles of C. sikamea treated with strains N7, RL8 and V4 had a significant weight gain compared to the control group. C. corteziensis juveniles treated with strains RL8 and BMix showed a significantly higher weight gain than the control group. No significant size increase was observed in any treated group for both oyster species. SOD activity significantly increased in C. sikamea treated with RL8 and with RL8, N7 and BMix in C. corteziensis. Streptomyces strains RL8 and N7 emerge as promising probiotic agents to cultivate C. sikamea and C. corteziensis and may also be useful to other molluscs and marine invertebrates .(AU)

O efeito de três culturas Streptomyces (N7, RL8 e V4) e uma mistura de Bacillus (BMix) sobre o cresimento (Peso, Tamanho) e atividade superóxido dismutase (SOD) em ostras jovens Crassostrea corteziensis e Crassostrea sikamea cultivadas artificalmente foi investigado para determinar seu potencial probiótico. Microorganismos foram adicionados à água de cultura a 1×10 6 CFU/ml uma vez por dia durante 30 dias e todas as ostras foram alimentadas diariamente com uma mistura de microalgas. Jovens C. sikamea tratados com culturas N7, RL8 e V4 tiveram ganho de peso significativo quando comparado ao grupo de controle. Jovens C. corteziensis tratados com culturas RL8 e BMix demonstraram peso significativamente mais algo que o grupo de controle. Nenhum aumento em tamanho foi observado em grupos tratados em ambas espécies. A atividade SOD foi significamente aumentada em C. sikamea treatado com RL8 e com RL8, N7 e BMix em C. corteziensis. Culturas Streptomyces RL8 e N7 surgem como agentes probióticos promissores para o cultivo de C. sikamea e C. corteziensis e podem ser úteis para outros moluscos animais marinhos invertebrados.(AU)

Photo-enhanced toxicity of undispersed and dispersed weathered Macondo crude oil to Pacific (Crassostrea gigas) and eastern oyster (Crassostrea virginica) larvae.

During the Deepwater Horizon oil spill rapid natural weathering of Macondo crude oil occurred during the transport of oil to coastal areas. In response to the DWH incident, dispersant was applied to Macondo crude oil to reduce the movement of oil to coastal regions. This study aimed to assess the narcotic and phototoxicity of water-accommodated fractions (WAFs) of weathered Macondo crude oil, and chemically-enhanced WAFs of Corexit 9500 to Pacific (Crassostrea gigas) and eastern (Crassostrea virginica) oyster larvae. Phototoxic effects were observed for larval Pacific oysters exposed to combinations of oil and dispersant, but not for oil alone. Phototoxic effects were observed for larval eastern oysters exposed to oil alone and combinations of oil and dispersant. Corexit 9500 did not exhibit phototoxicity but resulted in significant narcotic toxicity for Pacific oysters. Oyster larvae may have experienced reduced survival and/or abnormal development if reproduction coincided with exposures to oil or dispersant.

Biochemical bases of growth variation during development: a study of protein turnover in pedigreed families of bivalve larvae (Crassostrea gigas).

Animal size is a highly variable trait regulated by complex interactions between biological and environmental processes. Despite the importance of understanding the mechanistic bases of growth, predicting size variation in early stages of development remains challenging. Pedigreed lines of the Pacific oyster (Crassostrea gigas) were crossed to produce contrasting growth phenotypes to analyze the metabolic bases of growth variation in larval stages. Under controlled environmental conditions, substantial growth variation of up to 430% in shell length occurred among 12 larval families. Protein was the major biochemical constituent in larvae, with an average protein-to-lipid content ratio of 2.8. On average, 86% of protein synthesized was turned over (i.e. only 14% retained as protein accreted), with a regulatory shift in depositional efficiency resulting in increased protein accretion during later larval growth. Variation in protein depositional efficiency among families did not explain the range in larval growth rates. Instead, changes in protein synthesis rates predicted 72% of growth variation. High rates of protein synthesis to support faster growth, in turn, necessitated greater allocation of the total ATP pool to protein synthesis. An ATP allocation model is presented for larvae of C. gigas that includes the major components (82%) of energy demand: protein synthesis (45%), ion pump activity (20%), shell formation (14%) and protein degradation (3%). The metabolic trade-offs between faster growth and the need for higher ATP allocation to protein synthesis could be a major determinant of fitness for larvae of different genotypes responding to the stress of environmental change.

Shifting Balance of Protein Synthesis and Degradation Sets a Threshold for Larval Growth Under Environmental Stress.

Exogenous environmental factors alter growth rates, yet information remains scant on the biochemical mechanisms and energy trade-offs that underlie variability in the growth of marine invertebrates. Here we study the biochemical bases for differential growth and energy utilization (as adenosine triphosphate [ATP] equivalents) during larval growth of the bivalve Crassostrea gigas exposed to increasing levels of experimental ocean acidification (control, middle, and high pCO2, corresponding to ∼400, ∼800, and ∼1100 µatm, respectively). Elevated pCO2 hindered larval ability to accrete both shell and whole-body protein content. This negative impact was not due to an inability to synthesize protein per se, because size-specific rates of protein synthesis were upregulated at both middle and high pCO2 treatments by as much as 45% relative to control pCO2. Rather, protein degradation rates increased with increasing pCO2. At control pCO2, 89% of cellular energy (ATP equivalents) utilization was accounted for by just 2 processes in larvae, with protein synthesis accounting for 66% and sodium-potassium transport accounting for 23%. The energetic demand necessitated by elevated protein synthesis rates could be accommodated either by reallocating available energy from within the existing ATP pool or by increasing the production of total ATP. The former strategy was observed at middle pCO2, while the latter strategy was observed at high pCO2. Increased pCO2 also altered sodium-potassium transport, but with minimal impact on rates of ATP utilization relative to the impact observed for protein synthesis. Quantifying the actual energy costs and trade-offs for maintaining physiological homeostasis in response to stress will help to reveal the mechanisms of resilience thresholds to environmental change.

Mitotic instability in triploid and tetraploid one-year-old eastern oyster, Crassostrea virginica, assessed by cytogenetic and flow cytometry techniques.

For commercial oyster aquaculture, triploidy has significant advantages. To produce triploids, the principal technology uses diploid × tetraploid crosses. The development of tetraploid brood stock for this purpose has been successful, but as more is understood about tetraploids, it seems clear that chromosome instability is a principal feature in oysters. This paper is a continuation of work to investigate chromosome instability in polyploid Crassostrea virginica. We established families between tetraploids-apparently stable (non-mosaic) and unstable (mosaic)-and normal reference diploids, creating triploid groups, as well as tetraploids between mosaic and non-mosaic tetraploids. Chromosome loss was about the same for triploid juveniles produced from either mosaic or non-mosaic tetraploids or from either male or female tetraploids. However, there was a statistically significant difference in chromosome loss in tetraploid juveniles produced from mosaic versus non-mosaic parents, with mosaics producing more unstable progeny. These results confirm that chromosome instability, as manifested in mosaic tetraploids, is of little concern for producing triploids, but it is clearly problematic for tetraploid breeding. Concordance between the results from cytogenetics and flow cytometry was also tested for the first time in oysters, by assessing the ploidy of individuals using both techniques. Results between the two were non-concordant.

Evaluation of toxicity of Deepwater Horizon slick oil on spat of the oyster Crassostrea virginica.

The 2010 explosion of the Deepwater Horizon (DWH) oil rig generated the largest marine oil spill in US history with millions of barrels of crude oil released in the Gulf of Mexico (GoM). The eastern oyster, Crassostrea virginica, is an ecologically and economically important species in the northern GoM. Due to its biological characteristics (sessile, filter feeding), juvenile oysters may have been affected. This study investigated the effects of surface-collected DWH oil prepared as high-energy water-accommodated fraction (HEWAF) on the survival of 2-month-old oyster spat, and evaluated the potential impacts of HEWAF on particle clearance rate and spat tissue. Exposure of oysters to a range of oil/HEWAF (0-7-66-147-908-3450 µg tPAH50 (sum of 50 polycyclic aromatic hydrocarbons) L-1) resulted in non-dose-dependent mortalities and reduced clearance rates of algal food (Tisochrysis lutea). A morphometric study of the digestive tubules (DGTs) indicated a dose-dependent response to oil exposure on lumen dilation, on epithelium thinning of the DGT, and a significant change in DGT synchrony (LOEC = 66 µg tPAH50 L-1). This finding suggests that structural changes occurred in the digestive gland of exposed oysters most likely due to an oil-related stress. In addition, histological observations showed that tissues in contact with HEWAF (gills, palp, connective tissue, digestive gland) were adversely impacted at ≥ 7 µg tPAH50 L-1, and exhibited pathological symptoms typical of an inflammatory response (e.g., hemocyte diapedesis and infiltration, syncytia, epithelium sloughing).

Growth, mortality and susceptibility of oyster Crassostrea spp. to Perkinsus spp. infection during on growing in northeast Brazil / Crescimento, mortalidade e susceptibilidade de ostras Crassostrea spp. à infecção por Perkinsus spp. em cultivo no Nordeste do Brasil

Abstract Crassostrea rhizophorae and C. gasar oysters are cultivated in the northeast region. Perkinsus parasites infect bivalves, and their effects on oysters from tropical regions are poorly understood. This study evaluated the impact of Perkinsus infection on the productive traits of native oysters. Oysters were sampled bimonthly during 7 months, from July 2010 to February 2011, to evaluate growth rate, mortality and shell color patterns (white and dark-gray) (n = 500), and to determine the prevalence and intensity of Perkinsus (n = 152). Perkinsus and Crassostrea species were determined using molecular tools. Results showed that most dark-gray (90%, n = 20) and white (67%, n = 18) oysters were C. gasar and C. rhizophorae, respectively. Oysters showed a high growth rate and moderate cumulative mortality (44%). C. gasar oysters grew better and showed lower mortality and lower incidence of Perkinsus compared to C. rhizophorae. The mean prevalence of Perkinsus was moderate (48%), but the infection intensity was light (2.2). Perkinsosis affected very small oysters (19.4 mm). In conclusion, native oysters, especially C. gasar, have a great potential for culture, mortality is not associated with perkinsosis, and the shell color of oysters can be used to improve selection for spats with better performance.

Resumo Crassostrea rhizophorae e C. gasar são cultivadas na região Nordeste. Parasitas Perkinsus infectam bivalves e seus efeitos em ostras de regiões tropicais são pouco compreendidos. Este estudo avaliou o impacto da infecção por Perkinsus em parâmetros de produção de ostras nativas. Ostras foram coletadas bimestralmente durante 7 meses, de julho de 2010 a fevereiro de 2011, para avaliar crescimento, mortalidade e padrão de coloração da concha (branca e cinza-escura) (n = 500); além da presença e intensidade de Perkinsus (n = 152). Perkinsus e Crassostrea foram identificados por abordagem molecular. Os resultados mostraram que as ostras cinza-escuras (90%, n = 20) e brancas (67%, n = 18) eram C. gasar e C. rhizophorae, respectivamente. As ostras mostraram uma boa taxa de crescimento e mortalidade acumulada moderada (44%). C. gasar cresceu melhor com menor mortalidade e menor incidência de Perkinsus que C. rhizophorae. A prevalência média de Perkinsus foi moderada (48%), mas a intensidade de infecção foi leve (2,2). A perkinsiose afetou ostras pequenas (19,4 mm). Em conclusão, ostras nativas, especialmente C. gasar, têm grande potencial de produção; sem mortalidade associada à perkinsiose; e, a cor da concha pode ser usada para melhorar a seleção de sementes com melhor desempenho.

Ocean acidification stimulates alkali signal pathway: A bicarbonate sensing soluble adenylyl cyclase from oyster Crassostrea gigas mediates physiological changes induced by CO2 exposure.

Ocean acidification (OA) has been demonstrated to have severe effects on marine organisms, especially marine calcifiers. However, the impacts of OA on the physiology of marine calcifiers and the underlying mechanisms remain unclear. Soluble adenylyl cyclase (sAC) is an acid-base sensor in response to [HCO3-] and an intracellular source of cyclic AMP (cAMP). In the present study, an ortholog of sAC was identified from pacific oyster Crassostrea gigas (designated as CgsAC) and the catalytic region of CgsAC was cloned and expressed. Similar to the native CgsAC from gill tissues, the recombinant CgsAC protein (rCgsAC) exhibited [HCO3-] mediated cAMP-forming activity, which could be inhibited by a small molecule KH7. After 16days of CO2 exposure (pH=7.50), the mRNA transcripts of CgsAC increased in muscle, mantle, hepatopancreas, gill, male gonad and haemocytes, and two truncated CgsAC forms of 45kD and 20kD were produced. Cytosolic CgsAC could be translocated from the cytoplasm and nuclei to the membrane in response to CO2 exposure. Besides, CO2 exposure could increase the production of cAMP and intracellular pH of haemocytes, which was regulated by CgsAC (p<0.05), suggesting the existence of a [HCO3-]/CgsAC/cAMP signal pathway in oyster. The elevated CO2 could induce an increase of ROS level (p<0.05) and a decrease of phagocytic rate of haemocytes (p<0.05), which could be inhibited by KH7. The results collectively suggest that CgsAC is an important acid-base sensor in oyster and the [HCO3-]/CgsAC/cAMP signal pathway might be responsible for intracellular alkalization effects on oxidative phosphorylation and innate immunity under CO2 exposure. The changes of intracellular pH, ROS, and phagocytosis mediated by CgsAC might help us to further understand the effects of ocean acidification on marine calcifiers.

Characterization and expression of a novel caspase gene: Evidence of the expansion of caspases in Crassostrea gigas.

Caspases are a group of cysteine-aspartate proteases involved in apoptosis and a variety of non-apoptotic processes. In this study, a novel caspase gene was cloned and its potential role in apoptosis was investigated. The caspase gene (CgCasp 3/7) has an open reading frame of 1626bp encoding 541 amino acids containing the conserved functional domains and motifs of effector caspases. Its amino acid sequence shows low identity with the other effector caspases of Crassostrea gigas and contains a unique long intersubunit linker (IL). The CgCasp 3/7 mRNA was expressed highly in oocytes and then decreased gradually after fertilization, indicating CgCasp 3/7 could function in oocyte apoptosis. In adult tissues, it is located primarily in the gills and hepatopancreas. We examined the mRNA expression of CgCasp 3/7 in gills of oysters immersed in ambient (17°C) or heated (27°C) seawater. The thermal stress stimulated mRNA expression of CgCasp 3/7 by 2.5- and 4.1-fold at 2h and 6h post-treatment, respectively, indicating CgCasp3/7 was involved in the early response to thermal stress. To examine the function of the IL, CgCasp 3/7 and CgCasp 3/7-T (with a truncated IL) were expressed using an in vitro translation system and their DEVDase activity was measured. Both proteins showed a significantly higher level of DEVDase activity than control, but CgCasp3/7-T had lower DEVDase activity than CgCasp3/7, indicating CgCasp3/7 had DEVDase activity and the IL was required for maximal DEVDase activity. Our study adds to the complexity of caspases in C. gigas.

Epizootiology of Perkinsus sp. inCrassostrea gasar oysters in polyculture with shrimps in northeastern Brazil / Epizootiologia de Perkinsus sp. em ostrasCrassostrea gasar em policultivo com camarões no Nordeste do Brasil

Abstract Bivalve culture is of considerable economic and social interest in northeastern (NE) Brazil. The polyculture is an alternative approach to traditional monoculture for reducing the environmental impact of shrimp farming and improving oyster culture. Perkinsus marinus andPerkinsus olseni were found infecting oysters in NE Brazil and can threaten oyster production. This study evaluatedPerkinsus spp. occurrence in Crassostrea gasar during all production stages. Oyster spats were produced in a hatchery and grown in shrimp ponds in Rio Grande do Norte state.Perkinsus spp. were surveyed by Ray’s fluid thioglycollate medium and confirmed by polymerase chain reaction. Prevalence and intensity of infection were determined in oysters until they reached 7 cm. Results showed that the broodstock was already infected by Perkinsus (60%), but the derived spats were Perkinsus-free. Oyster spats acquired Perkinsus infection when transferred to ponds. The prevalence gradually increased in the seven months following placement in ponds (73%), and then decreased to 17% by the tenth month. The infections were initially mild, but intensity increased at the final growth stage. In conclusion, it is possible to produce Perkinsus-free C. gasar oyster spats from infected broodstock, and their culture in shrimp ponds is feasible.

Resumo O cultivo de bivalves é de grande interesse econômico e social no Nordeste (NE) do Brasil. O policultivo é uma alternativa ao monocultivo tradicional de camarões para reduzir o impacto ambiental e melhorar a produção de ostras.Perkinsus marinus e Perkinsus olseni foram identificados infectando ostras no Nordeste do Brasil e representam uma ameaça a produção de ostras. Este estudo avaliou a ocorrência dePerkinsus spp. em Crassostrea gasardurante todas as fases de produção. Sementes de ostras foram produzidas em laboratório e cultivadas em viveiros de camarão no Rio Grande do Norte.Perkinsus spp. foram diagnosticados ​​com o uso do meio de tioglicolato fluido de Ray e confirmado por reação em cadeia da polimerase. A prevalência e intensidade de infecção foram determinadas em ostras até atingirem 7 cm. Os resultados mostraram que os reprodutores encontravam-se infectados porPerkinsus (60%), mas as sementes produzidas estavam livres de Perkinsus. As sementes adquiriram a infecção porPerkinsus quando transferidas para os viveiros. A prevalência aumentou gradualmente nos sete meses após a colocação nos viveiros (73%) e, em seguida, diminuiu para 17% até o décimo mês. As infecções foram inicialmente leves, mas aumentaram até a fase final do crescimento. Em conclusão, é possível produzir sementes de ostras C. gasarlivres de Perkinsus a partir de reprodutores infectados e seu cultivo em viveiros de camarão é viável.

Chronic effects of non-weathered and weathered crude oil and dispersant associated with the Deepwater Horizon incident on development of larvae of the eastern oyster, Crassostrea virginica.

The present study examined the effects of chronic exposure of eastern oyster (Crassostrea virginica) larvae to the water-accommodated fractions of fresh and weathered oils collected from the Deepwater Horizon incident, with and without additions of the dispersant Corexit 9500A, as well as to solutions of Corexit alone. Both shell growth of larvae exposed to test materials for a period of 10 d and larval settlement after 28 d of exposure were the most sensitive endpoints, with the 10-d growth endpoint being less variable among replicates. Growth and settlement endpoints were more sensitive than larval survival and normal development after 10 d and 28 d. Acute-to-chronic ratios calculated in the present study suggest that acute toxicities of oils and dispersant for oysters are not predictive of chronic effect levels for growth and settlement; therefore, chronic bioassays are necessary to assess these sublethal effects, in addition to standard 48-h acute toxicity tests. Comparison of 10% effective concentration (EC10) values for chronic 10-d growth and 28-d settlement endpoints with concentrations of total polycyclic aromatic hydrocarbons and dipropylene glycol n-butyl ether (a marker for Corexit) in seawater samples, collected during and after the Deepwater Horizon incident, indicated it was unlikely that elevated concentrations of water-soluble fractions of oil and dispersant in the nearshore environment had significant adverse effects on the growth and settlement of eastern oyster larvae. Environ Toxicol Chem 2016;35:2029-2040. © 2016 SETAC.

Evaluación del crecimiento y la sobrevivencia en cultivos de ostra japonesa desarrollados en Meanguera del Golfo, departamento de La Unión: en vínculo con CENDEPESCA / Growth assessment and survival of japanese oyster crops developed in Meanguera del Golfo, department of La Unión

En El Salvador, el cultivo de Ostra del Pacifico (Crassostrea gigas) es una actividad nueva, ya que en el país se desconocía la reproducción, el manejo de la semilla y el desarrollo del cultivo engorde en las zonas de cultivo. Es por ello que el Centro de Desarrollo de la Pesca y la Acuicultura (CENDEPESCA) juntamente con la cooperación técnica del Gobierno del Japón a través de la Agencia de Cooperación Internacional del Japón (JICA) ha implementado el "Proyecto para el Desarrollo de la Acuicultura de Moluscos en El Salvador" que ha introducido una nueva especie de ostra en El Salvador, la Ostra del Pacifico (Crassostrea gigas) con el objetivo de mejorar la calidad de vida de las comunidades de pescadores, que solamente se ha dedicado a la extracción de los recursos del medio natural, mas no al cultivo directamente a causa de la falta de recursos para la realización de la reproducción de los organismos, adquisición de la semilla e insumos para el desarrollo del cultivo. La Escuela Especializada en Ingeniería ITCA-FEPADE regional La Unión se unió a este esfuerzo y realizó una investigación en cooperación con CENDEPESCA, la cual inició con la siembra de 7,000 semillas en el sistema suspendido de Ostra japonesa, posterior a ello se elaboró un cronograma de trabajo para el control y se desarrollo del crecimiento del cultivo en los 6 meses de duración de la investigación,

In El Salvador, the cultivation of Pacific Oyster (Crassostrea gigas) is a new activity, due to, in the country, the reproduction, the handling of the seed and the development of the fattening crop in the cultivation areas were unknown. That is why the Center for the Development of Fisheries and Aquaculture (CENDEPESCA) together with the technical cooperation of the Government of Japan through the Japan International Cooperation Agency (JICA) has implemented the "Project for the Development of Aquaculture of Mollusks in El Salvador "that has introduced a new species of oyster in El Salvador, the Pacific Oyster (Crassostrea gigas) with the aim of improving the quality of life of the fishing communities, which has only been dedicated to the extraction of the resources of the natural environment, but not to the cultivation directly because of the lack of resources for the realization of the reproduction of the organisms, acquisition of the seed and inputs for the development of the crop. ITCA-FEPADE La Unión joined this effort and carried out an investigation in cooperation with CENDEPESCA, which began with the sowing of 7,000 seeds in the suspended system of Japanese Oyster, after which a schedule of work for the control and development of the growth of the crop in the 6 months of duration of the investigation,

Evaluación del crecimiento y la sobrevivencia de ostra japonesa (Cassostrea gigas) en cultivos desarrollados en Meanguera del Golfo, departamento de La Unión, El Salvador / evaluation of growth and survival of japanese oyster (Cassostrea gigas) in crops grown in Meanguera del Golfo, department of La Unión, El Salvador

La Escuela Especializada en Ingeniería ITCA-FEPADE Centro Regional MEGATEC La Unión, a través de la carrera "Técnico en Manejo Integrado de Recursos Costero Marinos, con especialidad en Acuicultura y Pesquería" y en coordinación con el Centro de Desa- rrollo de la Pesca y la Acuicultura (CENDEPESCA), se desarrolló el proyecto de investigación aplicada para determinar el crecimiento y sobre vivencia en cultivos de Ostra Japonesa, con la finalidad de buscar y proponer alternativas de cultivo a los productores acuícolas del municipio de Meanguera del Golfo, departamento de La Unión. Para la implementación de este proyecto de investigación, se realizó una siembra de 7,000 semillas de ostras, que fueron colocadas suspendidas en la columna de agua de un sistema de cultivo constituido por un Long Line y linternas de 5 pisos cada una. Al final del periodo de cultivo se cosecharon organismos con tamaño promedio de 5.5 cm, con una sobre vivencia del 7%. El mayor depredador encontrado fue el caracol (Cymatium wiegmanni) y el rango de temperaturas durante este periodo de cultivo fue de 30.1 y 30.5 °C.

The Specialized School in Engineering ITCA-FEPADE, regional Centre MEGATEC in La Unión, through its career "Technician in Integrated Control Coastal marine resources, with an aquaculture and fishery emphasis" and in conjunction with The Development of Fishing and Aquaculture Center (CENDEPESCA), implemented an applied research project to determine the growth and survival in Japanese oyster farming so as to find and propose farming alternatives to aquaculture producers from the municipality of Meanguera del Golfo, departamento de la Unión. To implement this research project, 7,000 oysters were farmed and placed hanging from the water column of a farming system made up of a Long line and flashlights of 5 levels each. By the end of the farming period, organisms with an average size of 5.5 cm were harvested with a 7% survival chance. The main oyster predator found was the (Cymatium wiegmanni) snail, and the temperature range during the farming period was between 30.1 and 30.5 °C.

Molecular cloning of two molluscan caspases and gene functional analysis during Crassostrea angulata (Fujian oyster) larval metamorphosis.

Caspases have been demonstrated to possess important functions in apoptosis and immune system in vertebrate. But there is less information reported on the oyster larval development. In the present work, two full-length molluscan caspase genes, named Cacaspase-2 and Cacaspase-3, were characterized for the first time from Fujian oyster, Crassostrea angulata. Which respectively encode two predicted proteins both containing two caspase domains of p20 and p10 including the cysteine active site pentapeptide "QACRG" and the histidine active site signature. Otherwise Cacaspase-2 also contains a caspase recruitment domain. Homology and phylogenetic analysis showed that Cacaspase-2 shared high similarity with initiator caspase-2 groups, but Cacaspase-3 clustered together with executioner caspase-3 groups. Cacaspase-2 and Cacaspase-3 mRNA were both highly expressed in gills and labial palp and were significantly expressed highly in larvae during settlement and metamorphosis. Through the whole mount in situ hybridization, the location of Cacaspase-2 is in the foot of the oyster larvae and the location of Cacaspase-3 is in both the foot and velum tissues. These results implied that Cacaspase-2 and Cacaspase-3 genes play a key role in the loss of foot and Cacaspase-3 gene has an important function in the loss of velum during larvae metamorphosis in C. angulata.

Genomic characterization and expression analysis of five novel IL-17 genes in the Pacific oyster, Crassostrea gigas.

Interleukin-17 (IL-17) is a proinflammatory cytokine that plays an important role in clearing extracellular bacteria and contributes to the pathology of many autoimmune and allergic conditions. In the present study, five novel IL-17 homologs were identified by searching and analyzing the Pacific oyster genome. All six CgIL-17 members (including a previously reported homolog) contained four conserved cysteines that were used in the formation of disulfide bonds. Phylogenetic analysis showed that all invertebrate IL-17s were clustered into one group, implying that invertebrate IL-17s evolved from one common ancestral gene and subsequently diversified. All CgIL-17s shared the same genomic structure, containing two exons and one intron, except for the CgIL-17-3 and CgIL-17-5 genes, which each had only one exon. The expression pattern of the CgIL-17 genes was analyzed by qRT-PCR in a variety of tissues and at different developmental stages, and these genes were highly expressed in the gill and digestive gland tissues. Moreover, the expression of the CgIL-17 family genes was significantly up-regulated in hemocytes challenged with Pathogen-Associated Molecular Patterns (PAMPs). CgIL-17-3 had a strong response to lipopolysaccharide (LPS) and heat-killed Vibrio alginolyticus (HKVA) challenge, while CgIL-17-5 and CgIL-17-6 can be activated by peptidoglycan (PGN), but not by heat-killed Listeria monocytogenes (HKLM). The distinct, up-regulated transcript levels of the CgIL-17s in response to PAMPs challenge further indicate that CgIL-17s are likely to be significant components of immune responses by playing diversified roles in host defense in the Pacific oyster. These findings suggest that CgIL-17s are involved in innate immune responses and further supports their conserved function in mollusks immunity.