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Identifying the main factors on spatial differences in net growth rate of Yesso scallop (Patinopecten yessoensis) in culture system is the key to effective aquaculture management and development. Coupling a 3D ecosystem model (ROMS-CoSiNE) with a dynamic energy budget model for scallops, a Yesso scallop culture ecosystem (YeSCE) model was established with which scallop growth was simulated with real seeding density and juvenile size from local aquaculture experiments from December 1, 2012 to November 30, 2013. Results show that the YeSCE model has reasonably simulated the environmental variation and scallop net growth rate in the Changhai sea area. The growth of scallops was slow in winter and midsummer and was limited mainly by temperature. Food availability was a key factor that contributed to the fast growth of the scallops during spring to early summer and in autumn. Generally, the scallops cultured in the north part of the Changhai sea area grew faster than those in the south; and the net growth rate for scallops cultured near the island was significantly higher compare to the others, which is probably correlated to the spatial distribution of food availability. Based on the correlation analysis, the spatial differences of the net growth rate were largely affected by the length of the match timing of temperatures and food availability. The results of this study provide a scientific support for optimizing bottom culture planning and adjusting bottom culture methods. [ABSTRACT FROM AUTHOR]

This study evaluated the gel and microstructure properties of scallop (Patinopecten yessoensis) male gonads hydrolysates (SMGHs) combined with xanthan gum (XG). SMGHs/XG hydrogel matrix properties and structures were elucidated via different analysis tools such as rheometry, LF‐NMR, FTIR, AFM, and Cryo‐SEM. The addition of XG significantly improved the rheological properties of SMGHs, as indicated by 3.1‐fold G′ and 1.3‐fold melting temperature with increasing the XG dose to 5.6 mg/ml. The corresponding decrease in the T23 relaxation time from 450.3 to 365.6 ms also signified the strong binding between SMGHs and XG. SMGHs/XG also had a higher proton density (T1 and T2 weighted images) due to the higher bound and free water content of the hybrid gel systems, respectively. Additionally, the blueshift in the amide I and II bands in SMGHs/XG further indicated stronger electrostatic interactions between SMGHs and XG. Such scenarios resulted in a well‐distributed and compact network with a rougher surface of SMGHs/XG in comparison to pure SMGHs and XG, as assessed by AFM and SEM. These results suggest that SMGHs/XG gel could be a potential hybrid gel applied in the food industry. Practical Application: Scallop (Patinopecten yessoensis) male gonads are edible, but are usually discarded during processing of scallop adductor. Because of its rich nutrition and gelation properties, scallop male gonads have a potential role in developing marine source‐protein as a functional food base. The SMGHs/XG binary gel would be potentially applied in delivery system in food and biological fields. Further study is undergoing to apply SMGHs/XG binary gel to embed bioactive compounds, such as curcumin and β‐carotene. [ABSTRACT FROM AUTHOR]

Various bond disrupting agents including NaCl, GuHCl, urea, and SDS were introduced to investigate the intermolecular interactions between scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and κ‐carrageenan (κ‐C), which were monitored by changes in rheological property, water distribution, conformation characterization and microstructure by using rheometer, low field‐NMR relaxometry, Fourier transform infrared (FTIR) spectroscopy, cryo‐scanning electron microscopy (cryo‐SEM), and confocal laser scanning microscopy. The results showed that the bond disrupting agents deteriorated the rheological property of SMGHs/κ‐C in a dose‐dependent manner. Indeed, at the same concentration of 2 M, NaCl deteriorated the SMGHs/κ‐C more obviously than GuHCl and urea. In addition, SMGHs/κ‐C with bond disrupting agents possessed higher relaxation times including T21 and T23, indicating the migration to free water direction of bound and free water. Moreover, the FITR results showed the red‐shift in water regions (amide A and B bands), amide I and II bands, and indicated the breakdown of hydrogen bonds and electrostatic interactions, indicating a disordered structure in SMGHs/κ‐C by various bond disrupting agents. Furthermore, cryo‐SEM results showed the change of SMGHs/κ‐C from a homogeneous network to a looser and ruptured one with larger void spaces, and indicated the disrupted and tattered microstructure of SMGHs/κ‐C by various bond disrupting agents. Additionally, SMGHs/κ‐C as well showed less aggregates stained by RITC by bond disrupting agents. These results suggest that electrostatic interactions would be mainly involved in the maintenance of SMGHs/κ‐C gel network. This study could provide theoretical and methodological basis for hydrogel products with modified gel strength and microstructure by understanding the intermolecular interactions in gel system. Practical Application: Scallop (Patinopecten yessoensis) male gonads as a high‐protein part of scallop, is usually discarded during processing despite its edibility. In recent years, scallop male gonads are regarded as good sources to develop protein matrices due to their high protein content and numerous nutrients. In this study, scallop male gonad hydrolysates (SMGHs) were obtained by trypsin‐treated process. The considerable gelation behavior of SMGHs indicated that the SMGHs could be potentially utilized as a novel thickener and additive in production of kamaboko gels, can, sausage and spread with marine flavor. [ABSTRACT FROM AUTHOR]

The purpose of this study was to confirm inosine monophosphate (IMP) generation and to clarify the decomposition pathway of adenosine monophosphate (AMP) by investigating the properties of AMP, IMP, and adenosine (AdR) decomposition enzymes in Japanese scallop (Patinopecten yessoensis). The results showed that IMP accumulated due to AMP decomposition via endogenous enzymes in scallops stored at both 4 °C and 20 °C. The AMP decomposition rate was highest in the supernatant of homogenized scallop adductor muscle, followed by the suspended solution and precipitate, while IMP could not be decomposed in scallop. The results indicated that the activity of AdR deaminase was very high, and this enzyme was involved in an intracellular process in scallop. Moreover, 1 min of heating exerted little influence on the AMP and AdR decomposition rates, while 5 min of heating induced enzyme denaturation. The IMP generation rate increased dramatically in scallop crude enzyme solution containing 5 mM ethylenediaminetetraacetic acid (EDTA). This suggests that the major pathway of AMP decomposition might change with variations in metal ion concentrations in Japanese scallop. Practical Application: IMP generation in Japanese scallop (Patinopecten yessoensis) caused by endogenous enzymes was confirmed. IMP is very important for the umami taste (a pleasant savory taste) of aquatic products. As IMP accumulation might be achieved by changing the concentration of divalent metal ions and no IMP 5'‐nucleotidase activity was detected in scallop, a suitable process to produce good flavor scallops with high IMP contents might be developed. [ABSTRACT FROM AUTHOR]

The determination of the geographical origin of seafood products is important for food safety and health of consumers. A reliable method for tracing the geographical origin of scallop is urgently needed. The present study was the first attempt to trace the geographical origins of Yesso scallop (Patinopecten yessoensis) by using stable isotope techniques in different seasons. A total of 127 P. yessoensis samples from six sampling locations were collected in autumn of 2015 and spring of 2016. δ13C and δ15N values of bulk samples, as well as δ13C values of amino acids and monosaccharides, were determined by isotope-ratio mass spectrometry. The bulk δ13C values (−20.99‰ to −17.72‰), δ15N values (4.29‰–9.69‰), and δ13C values of amino acids (−37.26‰ to −9.25‰) and monosaccharides (−41.34‰ to −27.23‰) showed various characteristics for samples from different locations and different seasons. Multiway analysis of variance results demonstrated that the δ13C values of alanine, glycine, valine, leucine, serine, phenylalanine, fucose, rhamnose, glucose and mannose were negligibly affected by seasons. Based on the discriminant models built with these 10 parameters, the predictions of the geographical origin of P. yessoensis gave an overall correct classification rate of 100.0% and a cross-validation rate of 100.0%. The compound-specific isotope analysis was an applicable method to trace the geographical origins of P. yessoensis , which could avoid the interference of seasonal effect. • Yesso scallops from six locations and two seasons were collected for study. • δ13C values of both Amino acid and monosaccharide were analyzed. • Season significantly affected the δ13C values of Ara, Glu and Pro. • The classification efficiency of the proposed LDA models was 100%. • CSIA can effectively overcome the seasonal effect in tracing Yesso scallop. [ABSTRACT FROM AUTHOR]

A 49‐day rearing trial was conducted to investigate the effects of Pseudoalteromonas sp. F15 on growth, survival, digestive and immune‐related enzyme activities in larval and juvenile Yesso scallop, Patinopecten yessoensis. Larvae (Day 2 post‐fertilization) (d2 PF)) were provided with a diet only of microalgae (control) and supplemented with F15 at final concentrations of 1×104 and 1×106 cells/mL, respectively. Results indicated that the specific growth rates and survival rates of umbo larvae (d13 PF), crawling pediveliger larvae (d28 PF) and juveniles (d51 PF) fed the F15 supplementation diets at 104 and/or 106 cells/mL were significantly higher than those fed the diet of microalgae. Larvae and juveniles fed 104 and/or 106 cells/mL F15 supplementation diets showed a significant increase in pepsin, amylase and cellulase activities compared with the control group. The lysozyme, superoxide dismutase and catalase activities of larvae and juveniles fed the F15 supplementation diets at 104 and/or 106 cells/mL significantly increased compared to those fed the diet of microalgae. In addition, F15 protected juveniles against challenge with Vibrio splendidus. These data suggest that F15 can be useful in scallop larviculture. [ABSTRACT FROM AUTHOR]

Abstract The microphthalmia-associated transcription factor (MITF) is the center of the regulator network of melanin synthesis in vertebrates. However, the role of MITF in shell color formation is poorly studied in mollusks. In the present study, an MITF gene, PyMITF , was first identified at the whole-genome level in Yesso scallop (Patinopecten yessoensis), an evolutionarily and economically important species, the shell color of which shows polymorphism. The PyMITF is a large gene spanning ~37 kb in the genome with 7 introns and 8 exons. A basic helix-loop-helix leucine zipper (bHLH-LZ) domain was detected in the PyMITF protein sequence, which can bind the canonical E-box sequence in the promoter region of the downstream genes. Phylogenetic analysis of the MITFs among vertebrates and invertebrates revealed that the molecular evolution of MITFs was consistent with the species taxonomy. Different expression levels of PyMITF were detected among different shell color strains, indicating the important role of PyMITF involved in shell pigmentation. Besides, PyMITF was expressed at a significantly higher level in the central mantle than that in the edge mantle, proving the participation of the central mantle in shell color formation in molecular level for the first time. The work provides valuable information for the molecular mechanism study of shell color formation. Highlights • This is the first report of the genome-wide identification and characterization of an MITF gene in mollusk. • Expression levels of PyMITF were first detected in different mantle regions. • Significant differences in the PyMITF expression levels existed among different shell color scallops. [ABSTRACT FROM AUTHOR]

Abstract The development of bivalves has been extensively studied over the last 150 years. Despite this, the developmental dynamics of myogenesis in bivalves remains largely unknown, particularly at the early developmental stages. In the present study, we investigate the characteristics of muscle development of Yesso scallop Patinopecten yessoensis by phalloidin staining, light, electron and confocal microscopy. Myoblasts containing chaotic myofilaments are initially found in the blastocoel of trochophore, and become more organized during the transformation from trochophore into veliger. This is followed by a well-structured musculature including an anterior adductor, velum retractors and ventral retractors at the early veliger stage. With development into late veliger, larval muscle system is composed of the branched velum retractors and ventral retractors, anterior and posterior adductors. The most striking change for pediveliger is the development of foot retractor and mantle related muscles at this stage. During metamorphosis, the retractor muscles and anterior adductor undergo the irreversible shrink until vanishing completely towards the end of larval life, which coincide with the growth of foot retractor and mantle margin. All retractor muscles are found to be composed of striated fibres, whereas the adductor muscles have both smooth and striated components. The present study provides new evidences on the dynamic pattern of myogenesis during embryonic and larval development in scallops, which will greatly improve our understanding of scallop myogenesis and provide the basis for comparative analysis of muscle development in bivalves. Highlights • We reveal that myoblasts containing some chaotic myofilaments initially appear at the early trochophore stage. • The present study provides new evidences on the dynamic pattern of myofilament organization from trochophore to veliger. • Myoblasts become well-structured at veliger stages, but undergo a dramatic reorganization after metamorphosis. • The findings on myogenesis shed new lights on the comparative analysis of muscle development and hatchery production. [ABSTRACT FROM AUTHOR]

Highlights • Developed a scallop production model coupling DEB and ROMS. • Successfully assessed carrying capacity in the largest scallop ranching in China. • Food and temperature are main factors determining optimal densities in studied area. Abstract A production model has been developed to estimate scallop bottom culture carrying capacity. The model coupled pelagic system, scallop energetics and population dynamics with hydrodynamics. The methodology considers temperature and particle organic carbon (POC) were used to determine the carrying capacity through scallop growth, production and economic benefit. The model was applied to the Zhangzidao culture area in the North Yellow Sea, the largest marine ranching of Japanese scallops Patinopecten yessoensis in China. The studied area was divided into four boxes according to the temperature and depth gradients. The results showed that the model could successfully capture the main characteristics of the observed environmental variables, POC concentrations and biological behaviour of the cultured scallops. The food availability showed seasonal variations. The low temperature had also a great effect on the growth of the scallops in the south area during period of January to July. In contrary, the high temperature would cause high mortality rate of the scallops in the north area in September. Based on the production and profit, the optimal seeding densities were estimated to be 82,500, 105,000, 82,500, 60,000 in. ha−1, respectively in the Boxes1, 2, 3 and 4. There is the potential to increase the seeding density in the northeast area (Box 2), while the southwest area has already exceeded its capacity. The successful application of the model suggests that it could be used as a management tool for estimating the production carrying capacity in the bottom culture systems. [ABSTRACT FROM AUTHOR]

Ocean acidification (OA), which is caused by increasing levels of dissolved CO2 in the ocean, is a major threat to marine ecosystems. Multiple lines of scientific evidence show that marine bivalves, including scallops, are vulnerable to OA due to their poor capacities to regulate extracellular ions and acid-based status. However, the physiological mechanisms of scallops responding to OA are not well understood. In this study, we evaluated the effects of 45 days of exposure to OA (pH 7.5) on the energy metabolism and antioxidant capability of Yesso scallops. Some biochemical markers related to energy metabolism (e.g., content of glycogen and ATP, activity of ATPase, lactate dehydrogenase, glutamate oxaloacetate transaminase, and glutamate-pyruvate transaminase), antioxidant capacity (e.g., reactive oxygen species level, activity of superoxide dismutase, and catalase) and cellular damage (e.g., lipid peroxidation level) were measured. Our results demonstrate that the effects of the reduced pH (7.5) on scallops are varied in different tissues. The energy reserves are mainly accumulated in the adductor muscle and hepatopancreas. Yesso scallops exhibit energy modulation by increasing lactate dehydrogenase activities to stimulate anaerobic metabolism. The highly active Na+/K+-ATPase and massive ATP consumption in the mantle and gill indicate that a large amount of energy was allocated for the ion regulation process to maintain the acid-base balance in the reduced-pH environment. Moreover, the increase in the reactive oxygen species level and the superoxide dismutase and catalase activities in the gill and adductor muscle, indicate that oxidative stress was induced after long-term exposure to the reduced-pH environment. Our findings indicate that the effects of OA are tissue-specific, and physiological homeostasis could be modulated through different mechanisms for Yesso scallops. [ABSTRACT FROM AUTHOR]

In the present study, the rheological behavior of hydrolysates from scallop male gonad hydrolysates (SMGHs) was studied. The hydrolysates were obtained from scallop male gonads (SMGs) using papain. The changes in molecular mass of proteins in SMGHs were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that the proteins of SMGs were significantly degraded after hydrolysis with papain. The degree of hydrolysis reached to 17.8% and 20.8% for SMGHs treated by papain at 300 and 3,000 U/g protein, respectively. The SMGHs exhibited a weak strain overshoot behavior as well as non-Newtonian shear thinning flow behavior. Moreover, the rheological properties of SMGHs possessed a papain dose-dependent manner. These results suggest that SMGHs could be applied as a potential gelling and thickening agent in food formulations. [ABSTRACT FROM AUTHOR]

The 94-kDa glucose-regulated protein (GRP94) belonging to the HSP90 family is an endoplasmic reticulum (ER) chaperone. It plays critical roles in ER quality control, and has been implicated as a specialized immune chaperone to regulate both innate and adaptive immunity. In this study, we identified and characterized a GRP94 gene ( PyGRP94 ) from Yesso scallop ( Patinopecten yessoensis ). The protein sequence of PyGRP94 is highly conserved with its homologs in vertebrates, with a signal sequence in N-terminal, an ER retrieval signal sequence in C-terminal and a HATPase_c domain. Expression analysis suggests that PyGRP94 transcripts in early embryos are maternally derived and the zygotic expression is started from D-shaped larvae. This gene is also expressed in almost all the adult tissues examined except smooth muscle, with the highest expression level in hemocytes. Besides, PyGRP94 was demonstrated to be induced by heat shock and both Gram-positive ( Micrococcus luteus ) and Gram-negative ( Vibrio anguillarum ) bacterial infection, with much more dramatic changes being observed after V. anguillarum challenge. Our results suggest the involvement of PyGRP94 in response to thermal stress, and that it might play an important role in the innate immune defense of scallop. [ABSTRACT FROM AUTHOR]

Water temperature fluctuations are considered to be a major factor affecting the immune functions and metabolic processes of scallops. To better understand the immune defense mechanisms of Yesso scallop, Patinopecten yessoensis following exposure to water temperature fluctuations, transcriptomic profiles in the gills from high-frequency fluctuations (HF_G), low-frequency fluctuations (LF_G), and no fluctuations (NF_G) groups were obtained using HiSeq™ 2500 (Illumina). For HF_G, scallops were transferred directly between 18 and 8 °C every 4 h and for 10 fluctuations, while scallops in LF_G were transferred between 18 and 13 °C every 12 h, for a total of 4 fluctuations. A total of 442,922,590 clean reads were generated in 9 libraries and then assembled into 210,780 unigenes with an average length of 705 bp and an N50 of 1253 bp. Based on sequence similarity, 54,529 unigenes (25.87%) were annotated in at least one database. Comparative analysis revealed that 696 unigenes differentially expressed in temperature stressed groups compared with the control, including 229 unigenes between HF_G and NF_G, and 548 unigenes between LF_G and NF_G, respectively. Additionally, among these differentially expressed genes (DEGs), there were 41 immune-related unigenes and 16 protein metabolism-related unigenes. These results provide fundamental information on the molecular defense mechanisms in the Yesso scallop gills after exposure to water temperature fluctuations. [ABSTRACT FROM AUTHOR]

Cathepsin F is a unique papain cysteine proteinase with highly conserved structures: catalytic triad and a cystatin domain contained in the elongated N-terminal pro-region. It has been reported that cathepsin F is associated with the establishment of innate immune in several vertebrate including fish in aquaculture, but not known in bivalves. In this study, we firstly identified and characterized cathepsin F in the Yesso scallop ( Patinopecten yessoensis ). The protein structural and phylogenetic analyses were then conducted to determine its identity and evolutionary position. We've also investigated the expression levels of cathepsin F gene at different embryonic developmental stages, in healthy adult tissues and especially in the hemocytes and hepatopancreas after Gram-positive ( Micrococcus luteus ) and negative ( Vibrio anguillarum ) challenges using quantitative real-time PCR (qPCR). Cathepsin F was significantly up-regulated 3 h after infection of V. anguillarum in hemocytes, suggesting its participation in immune response. Our findings have provided strong evidence that cathepsin F may be a good target for enhancing the immune activity in Yesso scallop. [ABSTRACT FROM AUTHOR]

Abstract The inositol-requiring enzyme 1 (IRE1), one of the primary endoplasmic reticulum (ER) transmembrane receptor proteins, is involved in regulating unfolded protein response (UPR) signaling pathway and plays an import role in maintaining cell homeostasis. In the present study, an IRE1 homologue was identified from Patinopecten yessoensis (designated as PyIRE1). The cDNA of PyIRE1 was of 3314 bp with a 2646 bp open reading frame (ORF) of IRE1 encoding a polypeptide of 881 amino acids. There was a signal peptide, four pyrrolo-quinoline quinine (PPQ) domains, a transmembrane helix region, a Serine/Threonine protein kinases domain (S_TKc) and a protein kinases or N-glycanases containing protein domain (PUG) in the deduced amino acid sequence of PyIRE1. The PyIRE1 mRNA was constitutively expressed in all the tested tissues, with the highest expression level in gills. PyIRE1 protein was mainly located in the ER of P. yessoensis hemocytes. The expression profiles of PyIRE1, glucose-regulated protein 94 (designated as PyGRP94) and glucose-regulated protein 78 (designated as PyGRP78) were determined by SYBR Green qRT-PCR after heat shock treatment. The mRNA expression levels of all these three genes were significantly up-regulated and reached their peak values at 2 h (3.97-fold, p < 0.05), 8 h (19.67-fold, p < 0.05) and 4 h (27.37-fold, p < 0.05) in hemocytes, 2 h (3.55-fold, p < 0.05), 12 h (8.58-fold, p < 0.05) and 8 h (35.31-fold, p < 0.05) in gills after heat shock treatment, respectively. After the injection with PyIRE1 dsRNA, the mRNA expression of pro-apoptotic B-cell lymphoma-2 (Bcl-2) family member PyBax and the activity of caspase-3 significantly decreased in comparison with the control group ( p < 0.05) after heat shock treatment. These results collectively suggested that PyIRE1, as an ER stress sensor, was potentially involved in the response upon heat stress by regulating the expression of PyBax and apoptosis of hemocytes in P. yessoensis. Highlights • An IRE1 gene was identified from Yesso scallop Patinopecten yessoensis. • PyIRE1 was located in ER of hemocytes and mostly expressed in gills. • PyIRE1 mRNA increased significantly upon heat stress. • PyIRE1 could mediate apoptosis of hemocytes in the response to heat stress. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor 2 mRNA-binding proteins (IMPs) function in localization, stability and translational control of their target RNAs. In this study, we identified an IMP gene (PyIMP) from Yesso scallop, Patinopecten yessoensis. The complete DNA sequence of PyIMP was 22,875 bp, consisting of seventeen exons and sixteen introns. The full-length cDNA sequence was 3,293 bp, with an open reading frame of 1,776 bp, encoding 592 amino acids. PyIMP exhibited characters typical of IMPs, namely two RNA recognition motifs and four hnRNP K homology domains. Real-time quantitative reverse transcription PCR analysis indicated that PyIMP was universally expressed, with higher expression levels in the gonad of adult scallops, and in gastrulae and trochophore larvae at developmental stages. A synonymous mutation SNP, c.852A>G, which showed significant associations with growth traits of Yesso scallop, was identified in this gene. Scallops with the AA genotype at this locus had significantly higher trait values than those with the GG genotype for shell length, shell height, body weight, soft tissue weight and striated muscle weight (P < 0.05). Meanwhile, the expression of PyIMP in AA type scallops was significantly higher than that in the GG type, implying a positive effect of PyIMP on scallop growth. PyIMP represents the first mRNAbinding protein gene characterized in mollusks, and SNP c.852A>G will be useful for a better understanding of the role of mRNA-binding proteins in bivalves and for scallop breeding. [ABSTRACT FROM AUTHOR]

Background: Scallops possess striated and catch adductor muscles, which have different structure and contractile properties. The striated muscle contracts very quickly for swimming, whereas the smooth catch muscle can keep the shells closed for long periods with little expenditure of energy. In this study, we performed proteomic and transcriptomic analyses of differences between the striated (fast) and catch (slow) adductor muscles in Yesso scallop Patinopecten yessoensis. Results: Transcriptomic analysis reveals 1316 upregulated and 8239 downregulated genes in slow compared to fast adductor muscle. For the same comparison, iTRAQ-based proteomics reveals 474 differentially expressed proteins (DEPs), 198 up- and 276 downregulated. These DEPs mainly comprise muscle-specific proteins of the sarcoplasmic reticulum, extracellular matrix, and metabolic pathways. A group of conventional muscle proteins—myosin heavy chain, myosin regulatory light chain, myosin essential light chain, and troponin—are enriched in fast muscle. In contrast, paramyosin, twitchin, and catchin are preferentially expressed in slow muscle. The association analysis of proteomic and transcriptomic data provides the evidences of regulatory events at the transcriptional and posttranscriptional levels in fast and slow muscles. Among 1236 differentially expressed unigenes, 22.7% show a similar regulation of mRNA levels and protein abundances. In contrast, more unigenes (53.2%) exhibit striking differences between gene expression and protein abundances in the two muscles, which indicates the existence of fiber-type specific, posttranscriptional regulatory events in most of myofibrillar proteins, such as myosin heavy chain, titin, troponin, and twitchin. Conclusions: This first, global view of protein and mRNA expression levels in scallop fast and slow muscles reveal that regulatory mechanisms at the transcriptional and posttranscriptional levels are essential in the maintenance of muscle structure and function. The existence of fiber-type specific, posttranscriptional regulatory mechanisms in myofibrillar proteins will greatly improve our understanding of the molecular basis of muscle contraction and its regulation in non-model invertebrates. [ABSTRACT FROM AUTHOR]

Chemical state of cadmium in a hepatopancreas of a scallop (Patinopecten yessoensis) was studied by means of synchrotron radiation‐based X‐ray analytical techniques. X‐ray absorption fine structure (XAFS) and X‐ray fluorescence (XRF) imaging were used to identify the chemical state and the distribution of cadmium in the hepatopancreas, respectively. The results of invivo Cd K‐edge XAFS suggested that the neighboring atoms of the cadmium in the hepatopancreas are of sulfur. Therefore, we propose that cadmium was accumulated by a metalloprotein with sulfur. Micro XRF imaging of thin sections of the hepatopancreas showed that cadmium is distributed on the surface of intestinal epithelia and concentrated in the internal tissue of the hepatopancreas. These results indicated that scallops accumulate cadmium inside the hepatopancreas through the intestinal epithelium. [ABSTRACT FROM AUTHOR]

In this study, the effects of low-temperature long-time (LTLT) processing on the quality of Patinopecten yessoensis adductor muscle (PYAM) were investigated at 55°C. The texture of processed PYAM was characterized by textural profile analysis (TPA), and significant increases of cook loss, hardness, and shear force with time during LTLT processing were observed. The degradation of structural proteins was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and fragments with molecular weights of 208 kDa (myosin heavy chain, MHC), 97 kDa (paramyosin) and 35-40 kDa, respectively, were among the main products. Chemical characterization revealed elevated levels of activity in cathepsin L and caspase-3 and oxidation of proteins and lipids. Electron spin resonance spin trapping indicated reactive oxygen species (ROS) production in the PYAM during LTLT processing. Based on these results, it is proposed that the sequence of events in PYAM during LTLT processing includes ROS→ endogenous enzyme (involving caspase-3 and cathepsin L) activation →protein degradation→quality changes (texture and color). This revelation helps to further our understanding of the LTLT processing of PYAM, which would lead to better quality control for PYAM products. [ABSTRACT FROM AUTHOR]

This paper reports a toxic strain of Protoceratium reticulatum , its morphology, phylogeny, yessotoxins (YTXs) production and abundance in northern Yellow Sea of China from 2011 to 2015 was investigated. YTXs in hepatopancreas and edible parts of bottom sowing cultured Japanese scallop Patinopecten yessoensis in this sea area were determined weekly for 5 years. Other potential producers of YTXs, Gonyaulax spinifera and Lingulodinium polyedrum , were also investigated. Results revealed that Protoceratium reticulatum strain from the northern Yellow Sea belongs to a geographically widely distributed species. Motile cells of Protoceratium reticulatum contribute to YTXs in Japanese scallop, and G. spinifera may also be a potential contributor. Resting cysts of Protoceratium reticulatum , G. spinifera , and L. polyedrum in sediments were possibly important origins of YTXs in scallop cultured at sea bottom. YTXs in scallop decreased from 2011 to 2015, most toxins were concentrated in hepatopancreas, while a small portion in edible parts which was safe for consumption the whole year around. [ABSTRACT FROM AUTHOR]

The objective of the present study was to analyze the phenotypic stability of sex after sex differentiation in the Yesso scallop, which is a gonochoristic species that has been described as protandrous. So far, no study has investigated in detail the sexual fate of the scallop after completion of sex differentiation, although bivalve species often show annual sex change. In the present study, we performed a tracking experiment to analyze the phenotypic stability of sex in scallops between one and two years of age. We also conducted molecular marker analyses to describe sex differentiation and gonad development. The results of the tracking experiment revealed that all scallops maintained their initial sex phenotype, as identified in the last reproductive period. Using molecular analyses, we characterized my-dmrt2 and my-foxl2 as sex identification markers for the testis and ovary, respectively. We conclude by proposing that the Yesso scallop is a sex-stable bivalve after its initial sex differentiation and that it maintains a sex-stable maturation system throughout its life. The sex-specific molecular markers identified in this study are useful tools to assess the reproductive status of the Yesso scallop.

SOX family is composed of transcription factors that play vital roles in various developmental processes. Comprehensive understanding on evolution of the SOX family requires full characterization of SOX genes in different phyla. Mollusca is the second largest metazoan phylum, but till now, systematic investigation on the SOX family is still lacking in this phylum. In this study, we conducted genome-wide identification of the SOX family in Yesso scallop Patinopecten yessoensis and profiled their tissue distribution and temporal expression patterns in the ovaries and testes during gametogenesis. Seven SOX genes were identified, including SOXB1, B2, C, D, E, F and H, representing the first record in protostomes with SOX members identical to that proposed to exist in the last common ancestor of chordates. Genomic structure analysis identified relatively conserved exon-intron structures, accompanied by intron insertion. Quantitative real-time PCR analysis revealed possible involvement of scallop SOX in various functions, including neuro-sensory cell differentiation, hematopoiesis, myogenesis and gametogenesis. This study represents the first systematic characterization of SOX gene family in Mollusca. It will assist in a better understanding of the evolution and function of SOX family in metazoans. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLRs) play a crucial role in innate immunity by recognizing specific pathogen-associated molecular patterns, including lipoproteins, lipopeptides, lipopolysaccharide, flagellin, dsRNA, ssRNA and CpG DNA motifs. Although significant effects of TLRs on immunity have been reported in most vertebrates and some invertebrates, the complete TLR superfamily has not been systematically characterized in scallops. In this study, 18 TLR genes were identified from Yesso scallop ( Patinopecten yessoensis ) using whole-genome scanning. Phylogenetic and protein structural analyses were performed to determine the identities and evolutionary relationships of the 18 genes. Extensive expansion of TLR genes from the Yesso scallop genome indicated gene duplication events. In addition, expression profiling of PyTLRs was performed at different acidifying exposure levels (pH = 6.50, 7.50) with different challenge durations (3, 6, 12 and 24 h) via in silico analysis using transcriptome and genome databases. Our results confirmed the inducible expression patterns of PyTLRs under acidifying exposure, and the responses to immune stress may have arisen through adaptive recruitment of tandem duplications of TLR genes. Collectively, this study provides novel insight into PyTLRs as well as the specific role and response of TLR signaling pathways in host immune responses against acidifying exposure in bivalves. [ABSTRACT FROM AUTHOR]

Patinopecten yessoensis, is a species of scallop and a marine bivalve mollusk. In traditional East Asian medicine, scallop meat is used as a drug for the treatment of diabetes, pollakisuria, and indigestion. The present study was conducted in order to examine the potential anticancer effects of scallop flesh extract (SE) on MCF-7 human breast cancer cells. An MTT assay was used to evaluate cell viability and flow cytometry was used for the assessment of cell cycle distribution and apoptosis. The alteration in protein expression level was determined by western blot analysis, and the amounts of docosahexaenoic acid and eicosapentaenoic acid in the SE were measured by gas chromatography. SE inhibited the growth of MCF-7 human breast cancer cells in a dose-dependent manner by inducing G0/G1 phase arrest. The cell cycle arrest was associated with the upregulation of p53 and p21, and downregulation of G1 phase-associated cyclin D1/cyclin-dependent kinase (Cdk) 4 and cyclin E1/Cdk 2. In addition, SE-mediated cell cycle arrest was associated with the promotion of apoptosis, as indicated by the expression of apoptosis-associated proteins and changes in nuclear morphology. SE appeared to induce the mitochondrial apoptotic cascade, as indicated by a decreased expression of Bcl-2, activation of Bcl-2 associated X protein, release of cytochrome c, decrease in procaspase-3, and an increase in cleaved-poly (ADP-ribose) polymerase (PARP). Furthermore, the expression levels of Fas-associated via death domain and cleaved caspase-8 were increased in a SE dose-dependent manner. Taken together, these results suggest that the intrinsic and extrinsic pathways of apoptosis are associated with the anticancer effects of SE on MCF-7 cells. Thus, SE may be a suitable candidate for the treatment and prevention of human breast cancer. [ABSTRACT FROM AUTHOR]

Lectin (PYL) of molecular mass 17,154.5 Da that exhibited Gal/GalNAc-specificity was isolated from the scallop Patinopecten yessoensis. The lectin was completely inactivated by heating to 60°C for 30 min, exhibited the greatest activity at pH 5-9, and was metal-independent. It was shown that the lectin was involved in the mollusk protective mechanism by agglutinating the Gram-negative bacterium Vibrio proteolyticus. [ABSTRACT FROM AUTHOR]

The increasing amounts of artificial marine substrates, in many parts of the world have been proposed as a potential driver of Aurelia spp. blooms, on account of providing extra habitats for the settlement and the proliferation of the benthic stage (polyps). Previous experiments have mainly focused on the substrate choices of Aurelia spp. planulae. However, substrate preferences for the proliferation and immigration of polyps have not been reported. We monitored the propagation and immigration of Aurelia aurita (s. l.) polyps on two natural and nine artificial substrates at constant temperature (20±0.5°C) and salinity (30±0.5) in beakers and a glass aquarium in the laboratory, respectively. The results showed that, among artificial substrates, the highest number for polyp proliferation and immigration was found on nets, rigid polyvinyl chloride plates (RPVC), and wood. The lowest density of polyps was present on iron plates. Among natural substrates, the asexual reproduction rate of polyps on Patinopecten yessoensis (Jay, 1857) shells was significantly higher than Azumapecten farreri (Jones & Preston, 1904). On the account of the distinction in the roughness, chemical properties and biofilms of these material surfaces, bare artificial or natural substrates discriminatively affect the proliferation and the immigration of Aurelia spp. polyps at laboratory. These observations suggest that, even in the natural environment, different materials and texture may influence the composition and the abundance of the fouling communities and the assemblages of polyps and, indirectly, have effects on the amounts of released medusae. [ABSTRACT FROM AUTHOR]

Ocean acidification and warming are predicted to affect the ability of marine bivalves to build their shells, but little is known about the underlying mechanisms. Shell formation is an extremely complex process requiring a detailed understanding of biomineralization processes. Sodium incorporation into the shells would increase if bivalves rely on the exchange of Na + /H + to maintain homeostasis for shell formation, thereby shedding new light on the acid-base and ionic regulation at the calcifying front. Here, we investigated the combined effects of seawater pH (8.1, 7.7 and 7.4) and temperature (16 and 22 °C) on the growth and sodium composition of the shells of the blue mussel, Mytilus edulis , and the Yesso scallop, Patinopecten yessoensis . Exposure of M . edulis to low pH (7.7 and 7.4) caused a significant decrease of shell formation, whereas a 6 °C warming significantly depressed the rate of shell growth in P . yessoensis . On the other hand, while the amount of Na incorporated into the shells of P . yessoensis did not increase in acidified seawater, an increase of Na/Ca shell with decreasing pH was observed in M . edulis , the latter agreeing well with the aforementioned hypothesis. Moreover, a combined analysis of the shell growth and sodium content provides a more detailed understanding of shell formation processes. Under acidified conditions, mussels may maintain more alkaline conditions favorable for calcification, but a significant decrease of shell formation indicates that the mineralization processes are impaired. The opposite occurs in scallops; virtually unaffected shell growth implies that shell mineralization functions well. Finding of the present study may pave the way for deciphering the mechanisms underlying the impacts of ocean acidification and warming on bivalve shell formation. [ABSTRACT FROM AUTHOR]

Heat shock protein 70 (Hsp70s) family members are present in virtually all living organisms and perform a fundamental role against different types of environmental stressors and pathogenic organisms. Marine bivalves live in highly dynamic environments and may accumulate paralytic shellfish toxins (PSTs), a class of well-known neurotoxins closely associated with harmful algal blooms (HABs). Here, we provide a systematic analysis of Hsp70 genes ( PyHsp70 s) in the genome of Yesso scallop ( Patinopecten yessoensis ), an important aquaculture species in China, through in silico analysis using transcriptome and genome databases. Phylogenetic analyses indicated extensive expansion of Hsp70 genes from the Hspa12 sub-family in the Yesso scallop and also the bivalve lineages, with gene duplication events before or after the split between the Yesso scallop and the Pacific oyster. In addition, we determined the expression patterns of PyHsp70s after exposure to Alexandrium catenella, the dinoflagellate producing PSTs. Our results confirmed the inducible expression patterns of PyHsp70s under PSTs stress, and the responses to the toxic stress may have arisen through the adaptive recruitment of tandem duplication of Hsp70 genes. These findings provide a thorough overview of the evolution and modification of the Hsp70 family, which will gain insights into the functional characteristics of scallop Hsp70 genes in response to different stresses. [ABSTRACT FROM AUTHOR]

Calreticulin (CRT) is a multifunctional and highly conserved Ca 2+ -binding protein shared among vertebrates and invertebrates. In this study, we cloned and characterized a CRT gene, PyCRT , from Yesso scallop, Patinopecten yessoensis . The full-length cDNA of PyCRT was 1830 bp, including a 1242 bp open reading frame (ORF), a 29 bp 5′-untranslated region and a 559 bp 3′-untranslated region. PyCRT was consisted of three distinct structural and functional domains (N-, P- and C-domains), a signal peptide and an endoplasmic reticulum (ER) retrieval signal sequence (HDEL). Tissue specific expression analysis showed that PyCRT was distributed widely in Yesso scallop, and was highly expressed in the mantle and hemocytes. After Vibrio anguillarum challenge, the expression of PyCRT in hemocytes had a significant increase and reached the maximum level at 12 h post-infection. We also demonstrated for the first time in mollusc that the recombinant PyCRT (rPyCRT) could bind to the Gram-negative bacterium V. anguillarum , Escherichia coli and the Gram-positive bacterium Staphylococcus aureus . Our results suggested that the CRT gene from Yesso scallop possessed immune-related regulatory functions in the innate immune system in scallops. [ABSTRACT FROM AUTHOR]

The innate immune system plays a pivotal role in defending invasion of microorganisms for scallops. Previous studies on immune-related genes in the Yesso scallop, Patinopecten yessoensis (Jay, 1857) have mainly focused on characterization and expression pattern in response to bacterial challenge, no research has been carried out on the cytogenetic level yet. In the present study, eight fosmid clones containing the sequences of key immune-related genes (PyNFkB, PyTRAF2, PyTRAF4, PyTRAF7, PyMyd88-1, PyMyd88-3, PyMKK-7 and PyTNFR) were isolated and seven of them were successfully mapped on chromosomes of P. yessoensis utilizing fluorescence in situ hybridization. Wherein, PyMyd88-1, PyMyd88-3 and PyMKK-7 located on the same chromosome pair with adjacent positions and the other genes were mapped on four non-homologous chromosome pairs, showing a similar distribution to another five model species. The isolation and mapping of such genes of the Yesso scallop will lay a foundation for studies such as assignment of interested genes to chromosomes, construction cytogenetic maps and so on. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor receptor-associated factor 3 (TRAF3) is an important adaptor that transmits upstream activation signals to induce innate immune responses. TRAF3 interacting protein 1 (TRAF3IP1) interacts specifically with TRAF3, but its function in innate immunity remains unclear, especially in marine invertebrates. In this study, to better understand the functions of TRAFs in innate immune responses, we identified and characterized the first bivalve TRAF3IP1 gene, PyTRAF3IP1, from Yesso scallop (Patinopecten yessoensis), one of the most important mollusk species for aquaculture. The PyTRAF3IP1 cDNA is 2,367 bp, with an open reading frame of 1,629 bp encoding 542 amino acids. Phylogenetic and protein structural analysis confirmed the gene's identity and revealed that PyTRAF3IP1 was more similar to vertebrate TRAF3IP1s than to those of invertebrates. PyTRAF3IP1 was expressed in all the adult tissues and developmental stages sampled, implying that it plays versatile roles in many biological processes. Furthermore, PyTRAF3IP1 expression was dramatically induced in the acute phase (3-6 h) after infection with both Gram-positive (Micrococcus luteus) and Gram-negative (Vibrio anguillarum) bacteria, even stronger induction being observed after V. anguillarum challenge. This is the first report of the characterization and immune response involvement of TRAF3IP1 in marine invertebrates, and suggests that TRAF3IP1 contributes to innate immunity in bivalves. [ABSTRACT FROM AUTHOR]

The Yesso scallop Patinopecten yessoensis displays polymorphism in shell colors, which is of great interest for the scallop industry. To identify genes involved in the shell coloration, in the present study, we investigate the transcriptome differences by Illumina digital gene expression (DGE) analysis in two extreme color phenotypes, Red and White. Illumina sequencing yields a total of 62,715,364 clean sequence reads, and more than 85% reads are mapped into our previously sequenced transcriptome. There are 25 significantly differentially expressed genes between Red and White scallops. EPR (Electron paramagnetic resonance) analysis has identified EPR spectra of pheomelanin and eumelanin in the red shells, but not in the white shells. Compared to the Red scallops, the White scallops have relatively higher mRNA expression in tyrosinase genes, but lower expression in other melanogensis-associated genes. Meantime, the relatively lower tyrosinase protein and decreased tyrosinase activity in White scallops are suggested to be associated with the lack of melanin in the white shells. Our findings highlight the functional roles of melanogensis-associated genes in the melanization process of scallop shells, and shed new lights on the transcriptional and post-transcriptional mechanisms in the regulation of tyrosinase activity during the process of melanin synthesis. The present results will assist our molecular understanding of melanin synthesis underlying shell color polymorphism in scallops, as well as other bivalves, and also help the color-based breeding in shellfish aquaculture. [ABSTRACT FROM AUTHOR]

Mitogen-activated protein kinases (MAPKs) are protein Ser/Thr kinases that play a vital role in innate immune responses by converting extracellular stimuli into a wide range of cellular responses. Although MAPKs have been extensively studied in various vertebrates and invertebrates, our current understanding of MAPK signaling cascade in scallop is in its infancy. In this study, three MAPK genes ( PyERK , PyJNK , and Pyp38 ) were identified from Yesso scallop Patinopecten yessoensis . The open reading frame of PyERK , PyJNK , and Pyp38 was 1104, 1227, and 1104 bp, encoding 367, 408, and 367 amino acids, respectively. Conservation in some splicing sites was revealed across the three PyMAPK s, suggesting the common descent of MAPKs genes. The expression profiles of PyMAPKs over the course of ten different developmental stages showed that they had different expression patterns. In adult scallops, PyMAPKs were primarily expressed in muscles, hemocytes, gill, and mantle. To gain insights into their role in innate immunity, we investigated their expression profiles after infection with Gram-positive bacteria ( Micrococcus luteus ) and Gram-negative bacteria ( Vibrio anguillarum ). Significant difference in gene expression was only found in PyERK and PyJNK , but not Pyp38 , suggesting Pyp38 may not participate in immune response to bacterial infection. Besides, PyERK and PyJNK exhibited more drastic change against the invasion of V. anguillarum than M. luteus , suggesting they could be more sensitive to Gram-negative bacteria than Gram-positive bacteria. This study provides valuable resource for elucidating the role of MAPK signal pathway in bivalve innate immune response. [ABSTRACT FROM AUTHOR]

Marine mollusks provide shelter to epibiotic organisms which settle on the outer surface of their hard shells. Epibionts can exert beneficial or detrimental effects on the host mollusk. In this study, the ecology of the association of the commercially valuable marine mobile scallop Patinopecten ( =Mizuhopecten) yessoensis with its epibiotic barnacle Balanus rostratus was investigated. Fatty acid analysis was performed to determine the trophic relationships between these species. The distribution of fatty acid markers in this scallop species suggests an important contribution of diatoms, flagellates and animal material in its diet. The fatty acid analysis indicated a predominance of diatoms in the diet of the adult barnacles and some detrital input into the diets of young individuals. It was found that adult barnacles may compete with the scallops for food sources such as diatoms and zooplankton. It was revealed that with a negligible biomass of epibionts, the interactions between the barnacle and scallop may be regarded as commensalisms. An increase in the weight of epibiotic barnacles resulted in decreases in the weights and shell heights of the scallops, testifying to the adverse influence of a high biomass of epibionts on their host. [ABSTRACT FROM AUTHOR]

Water temperature can be a significant environmental stressor that affects the physiological and biochemical responses of mollusks. Yesso scallop, Patinopecten yessoensis , is influenced by water temperature fluctuations caused by the Northern Yellow Sea Cold Water Mass. Here, the effects of acute seawater temperature change, gradual temperature change, and fluctuating temperature on the physiological and enzymatic activities in Yesso scallop were studied . Scallops were transferred directly from rearing temperature (15 °C) to 5, 10, or 20 °C for the acute water temperature change treatment. Scallops in the gradual water temperature change treatment were acclimated to different temperatures (5, 10, and 20 °C) by increasing or decreasing seawater temperature progressively (1–2 °C/day). The results showed that oxygen consumption and ammonia-N excretion rates in the 20 °C-acute water temperature change treatment were significantly higher than those in the gradual treatment (one-way ANOVA, P < 0.01). However, scallop ingestion rate decreased significantly in response to an acute water temperature decrease from 15 to 5 °C, compared with equivalent groups exposed to a gradual temperature drop (one-way ANOVA, P < 0.01). Moreover, hepatopancreatic superoxide dismutase (SOD), catalase (CAT), acid phosphatase (ACP), and lysozyme (LSZ) activities reached their highest levels in the 20 °C-acute treatment after 12 h. Malondialdehyde (MDA) content increased significantly following the acute water temperature changes and reached the highest level in 10 °C-acute treatment after 72 h. Heat shock protein70 gene ( Hsp70 ) expression levels also increased significantly when water temperature was increased rapidly from 15 to 20 °C or decreased rapidly from 15 to 10 °C ( P < 0.01). In the fluctuation treatment, seawater temperature was altered every 12 h for a total of six fluctuations. Scallops were transferred directly from 15 to 7 °C (first fluctuation), moved from 7 to 15 °C for the next 12 h (second fluctuation), and then transferred from 15 to 7 °C again (third fluctuation) and so on. As results, significant increases in SOD and CAT activities and MDA content, and decreases in ACP and LSZ activities were observed (one-way ANOVA, P < 0.01). Significantly upregulated Hsp70 expression was also found in hemocytes, gills, and the adductor muscle of scallops in the fluctuating temperature treatment (one-way ANOVA, P < 0.01). In conclusion, acute water temperature changes and fluctuations impacted the physiological and enzymatic activities of Yesso scallops and upregulated Hsp70 expression. [ABSTRACT FROM AUTHOR]

Construction of cytogenetic maps can provide important information for chromosome identification, chromosome evolution and genomic research. However, it hasn't been conducted in many scallop species yet. In the present study, we attempted to map 12 fosmid clones containing tandem repeats by fluorescence in situ hybridization (FISH) in the Yesso scallop Patinopecten yessoensis (Jay, 1857). The results showed 6 fosmid clones were successfully mapped and distributed in 6 different pairs of chromosomes. Three clones were respectively assigned to a pair of metacentric chromosomes, a pair of submetacentric chromosomes and a pair of telocentric chromosomes and the remaining 3 clones showed their loci on three different pairs of subtelocentric chromosomes by co-hybridization. In summary, totally 8 pairs of chromosomes of the Yesso scallop were identified by 6 fosmid clones and two rDNA probes. Furthermore, 6 tandem repeats of 5 clones were sequenced and could be developed as chromosome specific markers for the Yesso scallop. The successful localization of fosmid clones will undoubtedly facilitate the integration of linkage groups with cytogenetic map and genomic research for the Yesso scallop. [ABSTRACT FROM AUTHOR]

The tumor necrosis factor (TNF) receptor associated factors (TRAFs) are the major signal transducers for the TNF receptor superfamily and the interleukin-1 receptor/Toll-like receptor (IL-1R/TLR) superfamily, which regulate a variety of cellular activities and innate immune responses. TRAF genes have been extensively studied in various species, including vertebrates and invertebrates. However, as one of the key component of NF-κB pathway, TRAF genes have not been systematically characterized in marine invertebrates. In this study, we identified and characterized five TRAF genes, PyTRAF2 , PyTRAF3 , PyTRAF4 , PyTRAF6 and PyTRAF7 , in the Yesso scallop ( Patinopecten yessoensis ). Phylogenetic and protein structural analyses were conducted to determine their identities and evolutionary relationships. In comparison with the TRAF genes from vertebrate species, the structural features were all relatively conserved in the PyTRAF genes. To gain insights into the roles of TRAF genes during scallop innate immune responses, quantitative real-time PCR was used to investigate the expression profiles in the different stages of scallop development, in the healthy adult tissues, and in the hemocytes after bacterial infection with Micrococcus luteus and Vibrio anguillarum . Based on the qRT-PCR analysis, the expression of most of the PyTRAFs was significantly induced in the acute phases (3–6 h) after infection with Gram-positive ( M. luteus ) and Gram-negative ( V. anguillarum ) bacteria, and many more dramatic changes in PyTRAFs expression were observed after V. anguillarum challenge. Notably, the strong response in the up-regulation of PyTRAF6 post-bacterial challenge was distinct from that previously reported in scallops and crabs but was similar to that of other shellfish, Echinodermata and even teleost fish. The high level expressions of PyTRAFs in the hemocytes and the gill, and their specific expression patterns after challenges provide insights into the versatile roles and responses of TRAFs in the innate immune system against Gram-negative bacterial pathogens in bivalves. [ABSTRACT FROM AUTHOR]

Myeloid differentiation factor 88 (MyD88) is a pivotal adaptor in the TLR/IL-1R signaling pathway, which plays an important role in activating the innate immune system. Although MyD88 genes have been identified in a variety of species, they have not been systematically characterized in scallops. In this study, five MyD88 genes were identified in Yesso scallop ( Patinopecten yessoensis ), PyMyD88-1 , PyMyD88-2a , PyMyD88-2b , PyMyD88-3 and PyMyD88-4 , which consisted of two pairs of tandem duplications located on the same chromosome. To our knowledge, this is the largest number of MyD88 genes found in an invertebrate. Phylogenetic and protein structural analyses were carried out to determine the identities and evolutionary relationships of these genes. PyMyD88 s have highly conserved structures compared to MyD88 genes from other invertebrate species, except for PyMyD88-4 , which contains only a DD domain, suggesting the evolutionarily conserved form of this particular gene member. We investigated the expression profiles of PyMyD88 genes at different developmental stages and in healthy adult tissues and hemocytes after Micrococcus luteus and Vibrio anguillarum infection using quantitative real-time PCR (qRT-PCR). The expression of most PyMyD88 s was significantly induced in the acute phase (3–6 h) after infection with both gram-positive ( M. luteus ) and gram-negative ( V. anguillarum ) bacteria, with much more dramatic changes in PyMyD88 expression being observed after V. anguillarum challenge. Collectively, the abundance of MyD88 s and their specific expression patterns provide insight into their versatile roles in the response of the bivalve innate immune system to gram-negative bacterial pathogens. [ABSTRACT FROM AUTHOR]

There is yet no firm experimental evidence that the evolutionary ancient gonadotropin-releasing hormone GnRH (i.e., GnRH1) also acts in invertebrate gametogenesis. The objective of this paper is to characterize candidate invGnRH peptides of Yesso scallop Patinopecten yessoensis (i.e., peptide identification, immunohistochemical localization, and immunoquantification) in order to reveal their bioactive form in bivalves. Using mass spectrometry (MS), we identified two invGnRH (py-GnRH) peptides from the scallop nerve ganglia: a precursor form of py-GnRH peptide (a non-amidated dodecapeptide; py-GnRH12aa-OH) and a mature py-GnRH peptide (an amidated undecapeptide; py-GnRH11aa-NH 2 ). Immunohistochemical staining allowed the localization of both py-GnRH peptides in the neuronal cell bodies and fibers of the cerebral and pedal ganglia (CPG) and the visceral ganglion (VG). We found that the peptides showed a dimorphic distribution pattern. Notably, the broad distribution of mature py-GnRH in neuronal fibers elongating to peripheral organs suggests that it is multi-functional. Time-resolved fluorescent immunoassays (TR-FIA) enabled the quantification of each py-GnRH form in the single CPG or VG tissue obtained from one individual. In addition, we observed greater abundance of mature py-GnRH in VG compared with its level in CPG, suggesting that VG is the main producing organ of mature py-GnRH peptide and that py-GnRH may play a central regulatory role in neurons of scallops. Our study provides evidence, for the first time, for the presence of precursor and mature forms of invGnRH peptides in the nerve ganglia of an invertebrate. [ABSTRACT FROM AUTHOR]

Mitogen-activated protein kinase kinases (MKK) are the essential components of the evolutionarily conserved MAPK signaling cascade, which regulates a variety of cellular activities and innate immune responses. Although MKK genes have been extensively studied in various vertebrate and invertebrate species, they have not been systematically characterized in bivalves. In this study, we identified and characterized five MKK genes ( PyMKK1/2 , PyMKK4 , PyMKK5 , PyMKK3/6 and PyMKK7 ) in the Yesso scallop ( Patinopecten yessoensis ). Phylogenetic and protein structural analyses were conducted to determine their identities and evolutionary relationships. To gain insights into the possible roles of MKK genes during scallop innate immune responses, quantitative real-time PCR (qRT-PCR) was used to investigate their expression profiles during different developmental stages in samples taken from healthy adult tissues and hemocytes after Micrococcus luteus and Vibrio anguillarum bacterial infections. The Yesso scallop MKK s ( PyMKK s) were found to have highly conserved structural features compared to the MKK genes from other invertebrate species. Using qRT-PCR analysis, three distinct expression patterns were detected among the PyMKK s over the course of ten different developmental stages. In adult scallops, the majority of the PyMKK s were highly expressed in mantle, gill, muscle and hemocytes. The differential expression patterns of the five PyMKK s after M. luteus (Gram-positive) and V. anguillarum (Gram-negative) bacterial infections suggested their possible involvement in the innate immune response and provide the foundation and resource for the further study on innate immune response of MAPK signal pathway in mollusk. [ABSTRACT FROM AUTHOR]

In this paper, we present a decay equation for paralytic shellfish poisoning (PSP) toxins using long-term field data spanning more than 10 years in order to predict the detoxification period for the scallop Patinopecten yessoensis in Ofunato Bay, Japan. From the data, we obtained the date of maximum toxicity in the digestive gland (DG) of the scallop and then the date of detoxification. Next, we performed linear regression analysis between log-toxicities and days after the maximum toxicity level for each study year. Toxicity declined at a rate of 1.5 %/day, and a period of 3-9 months was required for the scallop to achieve a toxicity level of 20 mouse units (MU)/g DG tissue, which is a critical level for determining monitoring frequency and area of scallop toxicity. We then estimated the number of days needed to reach 20 MU/g DG tissue ( t) using the equations obtained by the above-mentioned analysis, and we performed another linear regression analysis between the log (maximum toxicity) and t for each year. The difference between the actual and predicted detoxification time ranged from −16 to 18 days. We conclude that these equations can be used to predict the depuration of PSP toxins from scallops in Ofunato Bay. [ABSTRACT FROM AUTHOR]

Patinopecten yessoensis is a commercial valuable species. This study deals with the effect of nutrient effects of the broodstock (mainly ovaries) on the larvae. Concentrations of total carbohydrate, total protein and total lipid in the gonads of P. yessoensis from three Hatcheries (Hatchery 1, Hatchery 2, and Hatchery 3) were determined before and after spawning. The relationship between the nutrient concentration in ovaries before spawning (BC) and that of larvae (LC) was assessed as well as the change in nutrient levels in ovaries after spawning (DC). Results indicate that the BC of total carbohydrate (7.66%) and total lipid (14.48%) in ovaries were significantly higher than in testes (5.20%, 5.20% respectively), whereas the BC of total protein in the ovaries was lower (61.76%) than in the testes (81.67%). The different gonadal composition suggests the different nutrient demands between male and female broodstocks in breeding season. Patinopecten yessoensis gonads contained a higher proportion of lipids, in comparison to other bivalves, which might be a response to the low ambient water temperatures. Further analysis of fatty acids showed that the concentrations of n-3PUFA, EPA and DHA in larvae (LC) were positively correlated with BC and DC, indicating the significant nutrient influence of broodstocks on the larvae. As these fatty acids are important in metabolism, and have been demonstrated to be influential to the viability of the larvae, larval growth and the settlement, spat growth, and juvenile survival in many bivalves, they could possibly be used as indexes to evaluate, and predict condition of broodstocks and larvae. [ABSTRACT FROM AUTHOR]

Rel/NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) genes are evolutionarily conserved and play a pivotal role in several physiological events. They have been extensively studied from various species, including both vertebrates and invertebrates. However, the Rel/NF-κB genes have not been systematically characterized in bivalves. In this study, we identified and characterized PyNF-κB and PyRel in the Yesso scallop ( Patinopecten yessoensis ). Phylogenetic and protein structural analyses were conducted to determine the identities and evolutionary relationships of Rel/NF-κB genes in Yesso scallop. Compared with the Rel/NF-κB genes from vertebrate species, the PyNF-κB and PyRel are relatively conserved in their structural features, but there were no paralogs found in P . yessoensis or other invertebrates. To gain insights into the roles of Rel/NF-κB genes during the innate immune response in scallop, quantitative real-time PCR was used to investigate the expression profiles of these genes at different developmental stages, in healthy adult tissues and in the hemolymph after bacterial infection with Micrococcus luteus and Vibrio anguillarum . The real-time PCR results indicated the abundance of PyNF-κB in the first four embryonic stages, including oocytes, fertilized eggs, morulae and blastulae. By contrast, PyRel was abundantly expressed in blastulae, trochophores and D-shaped larvae. In adult scallops, PyNF-κB and PyRel were ubiquitously expressed in most healthy tissues and highly expressed in most of the immune related tissues. Both genes were significantly up-regulated during the acute phase (3 h) after infection with Gram-positive ( M. luteus ) and negative ( V. anguillarum ) bacteria, while the much higher expression level of PyNF-κB suggested the involvement of the extra immune deficiency (IMD)-like pathway against the Gram-negative bacterial infection. The complex pattern of Rel/NF-κB induced expression suggested that PyNF-κB and PyRel both have specific and cooperative roles in the acute immune responses to bacterial infection. [ABSTRACT FROM AUTHOR]

Existing research on the role of gonadotropin-releasing hormone (GnRH) in bivalve reproduction is inadequate, even though a few bivalve GnRH orthologs have been cloned. The objective of this paper was to elucidate the in vivo effect of GnRH administration in Yesso scallop reproduction. We performed in vivo administration of scallop GnRH (py-GnRH) synthetic peptide into the developing gonad, and analyzed its effect on gonad development for 6 weeks during the reproductive season. The resulting sex ratio in the GnRH administered (GnRH(+)) group might be male biased, whereas the control (GnRH(-)) group had an equal sex ratio throughout the experiment. The gonad index (GI) of males in the GnRH(+) group increased from week 2 to 24.8% at week 6. By contrast the GI of the GnRH(-) group peaked in week 4 at 16.6%. No significant difference was seen in female GI between the GnRH(+) and GnRH(-) groups at any sampling point. Oocyte diameter in the GnRH(+) group remained constant (about 42–45 μm) throughout the experiment, while in the GnRH(-) group it increased from 45 to 68 μm i.e. normal oocyte growth. The number of spermatogonia in the germinal acini of males in the GnRH(+) group increased from week 4 to 6. Hermaphrodites appeared in the GnRH(+) group in weeks 2 and 4. Their gonads contained many apoptotic cells including oocytes. In conclusion, this study suggests that py-GnRH administration could have a potential to accelerate spermatogenesis and cause an inhibitory effect on oocyte growth in scallops. [ABSTRACT FROM AUTHOR]

Vitellogenin (Vg), the major precursor of the egg-yolk proteins, has been found to play an immune role in fish and protochordate amphioxus, however, no study on the immune function of Vg in invertebrates has ever been studied before. In this study, the complete cDNA of Vg was identified from the scallop Patinopecten yessoensis (termed PyVg ). The cDNA contained an open reading frame (ORF) of 6888 bp, encoding a polypeptide of 2295 amino acid protein, which had an N-terminal signal peptide followed by the mature Vg. The mature Vg had the domains Vitellogenin_N, domain of unknown function 1943 (DUF1943) and von Willebrand factor type D domain (VWD) as well as the consensus cleavage site (R-X-R/K-R) and conserved motif (KTIGNAG). Tissue distribution assay revealed that PyVg transcripts were predominantly present in the ovary and hepatopancreas, and its expression profile in ovary well reflected the annual cycle of vitellogenesis. Interestingly, bacterial challenge caused a significant change in PyVg expression, hinting an involvement of PyVg in the acute phase response in P. yessoensis . Consistently, recombinant DUF1943 and VWD domains both could interact with LTA and LPS on bacterial wall, and purified native PyVg displayed a broad-spectrum antibacterial activity against both Gram-negative ( Escherichia coli and Vibrio anguillarum ) and Gram-positive bacteria ( Staphylococcus aureus ). Overall, these data indicate that Vg is a pattern recognition molecule with bacterial growth-inhibiting activity in the scallop. [ABSTRACT FROM AUTHOR]

The Yesso scallop Patinopecten yessoensis is an economically important marine bivalve species in aquaculture and fishery in Asian countries. However, limited genomic resources are available for this scallop, which hampers investigations into molecular mechanisms underlying their unique biological characteristics, such as shell formation and pigmentation. Mantle is the special tissue of P. yessoensis that secretes biomineralization proteins inducing shell deposition as well as pigmentation on the shells. However, a current deficiency of transcriptome information limits insight into mechanisms of shell formation and pigmentation in this species. In this study, the transcriptome of the mantle of P. yessoensis was deeply sequenced and characterized using Illumina RNA-seq technology. A total of 86,521 unique transcripts are assembled from 55,884,122 reads that passed quality filters, and annotated, using Gene Ontology classification. A total of 259 pathways are identified in the mantle transcriptome, including the calcium signaling and melanogenesis pathways. A total of 237 unigenes that are homologous to 102 reported biomineralization genes are identified, and 121 unigenes that are homologous to 93 known proteins related to melanin biosynthesis are found. Twenty-three annotated unigenes, which are mainly homologous to calmodulin and related proteins, Ca2+/calmodulin-dependent protein kinase, adenylate/guanylate cyclase, and tyrosinase family are potentially involved in both biomineralization and melanin biosynthesis. It is suggested that these genes are probably not limited in function to induce shell deposition by calcium metabolism, but may also be involved in pigmentation of the shells of the scallop. This potentially supports the idea that there might be a link between calcium metabolism and melanin biosynthesis, which was previously found in vertebrates. The findings presented here will notably advance the understanding of the sophisticated processes of shell formation as well as shell pigmentation in P. yessoensis and other bivalve species, and also provide new evidence on gene expression for the understanding of pigmentation and biomineralization not only in invertebrates but also probably in vertebrates. [ABSTRACT FROM AUTHOR]

Toll-interacting protein (Tollip) is a critical regulator of Toll-like receptor (TLR)- mediated innate immune responses. However, the Tollip gene has not been systematically characterized in shellfish. In this study, we identified and characterized a Tollip gene, PyTollip, in Yesso scallop (Patinopecten yessoensis). Phylogenetic and protein structural analyses were conducted to determine its sequence identities and evolutionary relationships. Compared with Tollip genes from other invertebrate and vertebrate species, the PyTollip gene is highly conserved in its sequence and structural features, except that a unique asparagine residue was found at a conserved site in the C2 domain of PyTollip. Quantitative real-time PCR was used to investigate the expression profiles of PyTollip in different developmental stages, healthy adult tissues, and in hemolymph after Micrococcus luteus and Vibrio anguillarum bacterial infection. Real-time PCR analysis demonstrated differential expression of PyTollip at the acute phase (3 h) after infection with Gram-negative (V. anguillarum) and Gram-positive (M. luteus) bacteria. A second strong response of PyTollip expression was observed 24 h after challenge with V. anguillarum. Collectively, these results provide novel insights into the specific role and response of Tollip and TLR signaling pathways in host immune responses against different bacterial pathogens in bivalves. [ABSTRACT FROM AUTHOR]

Shell color is an important trait that is used in breeding the Japanese scallop Patinopecten yessoensis, the most economically important scallop species in China. We constructed four transcriptome libraries from different shell color lines of P. yessoensis: the left and right shell mantles of ordinary strains of P. yessoensis and the left shell mantles of the ‘Ivory’ and ‘Maple’ strains. These four libraries were paired-end sequenced using the Illumina HiSeq 2000 platform and contained 54,802,692 sequences, 40,798,962 sequences, 74,019,262 sequences, and 44,466,166 sequences, respectively. A total of 214,087,082 expressed sequence tags were assembled into 73,522 unigenes with an average size of 1,163 bp. When the data were compared against the public Nr and Swiss-Prot databases using BlastX, nearly 30.55% (22,458) of the unigenes were significantly matched to known unique proteins. Gene Ontology annotation and pathway mapping analysis using the Kyoto Encyclopedia of Genes and Genomes categorized unigenes according to their diverse biological functions and processes and identified candidate genes that were potentially involved in growth, pigmentation, metal transcription, and immunity. Expression profile analysis was performed on all four libraries and many differentially expressed genes were identified. In addition, 5,772 simple sequence repeats were obtained from the P. yessoensis transcriptomes, and 464,197, 395,646, and 310,649 single nucleotide polymorphisms were revealed in the ordinary strains, the ‘Ivory’ strain, and the ‘Maple’ strain, respectively. These results provide valuable information for future genomic studies on P. yessoensis and improve our understanding of the molecular mechanisms involved in the growth, immunity, shell coloring, and shell biomineralization of this species. These resources also may be used in a variety of applications, such as trait mapping, marker-assisted breeding, studies of population genetics and genomics, and work on functional genomics. [ABSTRACT FROM AUTHOR]

Neutrase-hydrolyzed male gonad of scallop (Patinopecten yessoensis) displayed a gelation-like profile, whereas the underlying mechanism was unknown. In this study, the microstructure and inter-molecular forces involved in the gel network of scallop (P. yessoensis) male gonad hydrolysates (SMGHs) were investigated, by monitoring changes of its gel strength in presence of different chemicals. The results showed that SMGHs chiefly consisted of peptides both below 1000 Da (46.86%) and above 10,000 Da (30.30%), and exhibited a porous, three-dimensional network, with firmness of 40.49 ± 1.96 g, cohesiveness of 479.02 ± 37.04 g·s and adhesive force of 23.69 ± 1.92 g, which were similar with that of 1.0–1.5% guar gum, 1.5% carrageenan, 1.0–2.0% xanthan gum and 0.5–1.5% gelatin. Addition of urea, and propylene glycol (PG) decreased the gel strength of SMGHs with the increase of concentration, and only a very weak gel was observed when the concentration of urea reached 8 M. The overall gel properties of SMGHs were improved in the presence of 0.3 M NaCl, KCl, CH3COONa and NaSCN (p < 0.05). However, elevated salt concentration led to decreased gel properties of SMGHs, especially the inhibiting effect of NaSCN at 3 M. In addition, inclusion of dithiothreitol (DTT), 2-mercaptoethanol (2-ME), and N-ethylmaleimide (NEM) also diminished the gel properties at high concentration (p < 0.05), but not severely, and their addition did not change the gelation-like profiles of SMGHs. These results suggest that the gel network of SMGHs was primarily maintained by hydrophobic, electrostatic interactions and hydrogen bonds. [ABSTRACT FROM AUTHOR]

Gelation is an important functional property of protein in meats. In this study, we prepared actomyosin from scallop Patinopecten yessoensis adductor muscles and studied the effects of pH on the physicochemical properties of the actomyosin preparation and on its heat-induced gel-forming properties. The results showed that the turbidity and surface hydrophobicity of scallop actomyosin increased with increases in the heating temperature, while the α-helical content concomitantly decreased. Higher turbidity and surface hydrophobicity and lower α-helical content were found to be easily obtained at lower pH values. A high water-holding capacity, strong gel strength, fine gel network and uniform ice crystals were all clearly observed at pH 7.0, indicating that a neutral pH was most beneficial for formation of the heat-induced scallop actomyosin gel. We therefore conclude that both the physicochemical properties of scallop actomyosin and its gel-forming ability during the heating process are pH dependent. [ABSTRACT FROM AUTHOR]