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The scale morphology of pleuronectiforms in the Gulf of Oman remains insufficiently known. This study used light microscopy and morphological analysis to examine scale variation across the flank of four Tonguefishes species; Cynoglossus arel, C. bilineatus, C. lingua, and C. puncticeps. Scales were extracted from six flank regions, three on the eyed and blind sides, respectively. The most differentiated species was C. arel, which showed significant differences in four size variables in five regions. In Cynoglossus arel and C. lingua, the scales of the eyed side were ctenoid, and those scales from the blind side were cycloid; C. puncticeps have ctenoid scales on both flank sides and C. bilineatus has cycloid scales on both sides. All species' scales on the blind side have fewer ctenial spines (except in C. bilineatus). This study indicated that scale morphology demonstrated considerable variation among the flank regions of the examined species. As a result, the scales from the head and the trunk regions of the eyed side and the scales from the head region of the blind side have a good power of species separation in this family. [ABSTRACT FROM AUTHOR]

The half‐smooth tongue sole, Cynoglossus semilaevis, is an important cultured flatfish species. Vibrio harveyi is a common pathogen to this fish, which may result in great economic loss to C. semilaevis culture industry. piRNAs, a non‐coding RNAs with 26–32 nt, have been regarded as promising biomarkers for cancer diagnosis and fish diseases. Here, we extracted the RNA from mucus of C. semilaevis and constructed the differential expression profiles of piRNAs between the sick fish (MS) and healthy fish (MC). We identified 45,696 differentially expressed piRNAs including 22,735 up‐regulated piRNAs and 22,961 down‐regulated piRNAs in MS group compared with MC group. The GO enrichment and KEGG pathway enrichment analyses of the differential piRNAs were carried out. The result showed immunity‐related target genes mainly involved in immune system process, response to stimulus, cell killing, immune system, infectious diseases and cell growth and death. The 10 most differentially expressed piRNAs were chosen to perform the qRT‐PCR, while only seven piRNAs were consistent with the sequence result. Compared with MC group, the expression levels of piR‐mmu‐72173>piR‐rno‐62831>piR‐xtr‐704880, piR‐dme‐15546979, piR‐mmu‐49941660, piR‐mmu‐29283297 and piR‐mmu‐1758399 were significantly lower, and piR‐gga‐10574 and piR‐gga‐134812 were significantly higher in MS group. These piRNAs may be potential biomarkers during the V. harveyi infection of C. semilaevis. This study could provide a new method to identify the infection status of C. semilaevis and understand better about the innate and adaptive immune system in C. semilaevis during bacterial infection. [ABSTRACT FROM AUTHOR]

As intracellular pathogen recognition receptors (PRRs), nucleotide‐binding domain, leucine‐rich repeat containing receptors (NLRs, NOD‐like receptors) are involved in innate immune responses in vertebrates. However, there is no systemic study on NLRs in Chinese tongue sole (Cynoglossus semilaevis), a popular maricultured fish in China. In the present study, a genome‐wide survey of NLRs was performed in C. semilaevis, with the identification of 29 NLRs, including five genes from the NLR‐A subfamily (referred to as CsNOD1‐5), two genes from the NLR‐B subfamily, 18 genes from the NLR‐C subfamily (referred to as CsNLR‐C1 to 18) and four other NLR genes. Phylogenetic analysis implied that CsNOD1‐5 contained conserved functional domains and had orthologous relationships with human NOD1‐5. Moreover, CsNLR‐C genes all possessed the FISHNA domain, which is a fish‐specific NACHT subdomain. Expression analysis showed that CsNOD1‐5 and CsNLR‐C1/2 were ubiquitously expressed in various normal tissues. Bacterial infection with Vibro harveyi revealed distinct expression patterns of all the tested CsNLRs in gill, intestine, trunk kidney, liver and spleen. In particular, CsNOD1‐4 and CsNLR‐C2 were significantly upregulated in gills at 48 h post bacterial infection. In addition, CsNOD3 and CsNOD4 were significantly elevated in infectious intestine, trunk kidney, liver and spleen, revealing that their expressions were more sensitive to bacterial infection than other CsNLRs. Together with the computational protein–protein interaction network of CsNLRs, it was suggested that individual NLR genes had different roles in the innate immune cascades of C. semilaevi against bacterial infection. This study provides valuable information for further studies on CsNLR immune function. [ABSTRACT FROM AUTHOR]

The ontogenesis of catabolic abilities and energy metabolism during endogenous nutritional periods of tongue sole was investigated. In this work, trypsin‐like proteases (TRY) and triglyceride lipase (LIP) activities were measured to assess the capacities to catabolize proteins and lipids, respectively. Meanwhile, specific enzymes including pyruvate kinase (PK), glutamic oxalo acetic transaminase (GOT) and glutamate dehydrogenase (GDH), and hydroxyacyl CoA dehydrogenase (HOAD) as well as their ratios were assayed to evaluate the abilities to use energy substrates of carbohydrates, amino acids and fatty acids, respectively, for energy production. In addition, activities of citrate synthase (CS) and lactate dehydrogenase (LDH) and LDH/CS ratio were calculated to analyse the evolution of aerobic and anaerobic pathways. The study found that hatching occurred at 38.8 h after fertilization (HAF), mouth‐opening day of eleuteroembryo appeared at 3 days after hatching (DAH), and the most rapid embryonic growth was observed in blastula stage before hatching. Enzymatic assay revealed that except for PK which appeared in cleavage stage onwards, all the other enzymes functioned after fertilization, preparing well for the coming embryogenesis of tongue sole. By comparing the average specific activity of enzyme in each period, it can be found that the highest value occurred at 3 DAH (for TRY, LIP, PK and LDH), 2 DAH (for GDH), fertilized egg (for GOT) and segmentation stage (for HOAD and CS), and the lowest value occurred at fertilized egg (for HOAD, CS and GDH), cleavage stage (for TRY, PK and LDH), gastrula stage (for GOT) and hatching day (for LIP). Based on the changeable patterns of metabolic enzymatic activities and ratios, it is concluded that metabolic capacities on three energy substrates displayed stage‐specific traits, and the dominant energy substrate was fatty acids before segmentation stage, amino acids until hatching day and carbohydrate during eleuteroembryo period. As for energy production mode, aerobic pathway appeared to increase greater in fertilized egg and gastrula stage, whereas anaerobic pathway played a predominant role during cleavage stage, blastula stage, segmentation stage and eleuteroembryo stage. These results are valuable to elucidate the nutritional requirements of embryonic stages in tongue sole and to further understand their energy metabolic mechanisms. [ABSTRACT FROM AUTHOR]

Perfluorooctane sulfonate (PFOS) is an increasingly important environmental pollutant that is pervasive in the environment. A number of studies have focused on the toxicological effects of PFOS on model fish species (zebrafish and medaka), but little is known about the impact of PFOS on commercially important marine fish. Thus, the present study examined transcriptome responses to PFOS exposure in the liver of juvenile Cynoglossus semilaevis, an important farmed flatfish in China. Then, in response to PFOS challenges, 1695 and 5244 genes were identified as significantly increased and depressed, respectively. Significant expression changes were observed in immune‐related genes (cytokine–cytokine receptor interaction, T‐helper [Th]17 cell differentiation, and the chemokine nuclear factor‐kappa B and T‐cell receptor signaling pathways), indicating that immunotoxicity is a key aspect of the effects of PFOS on C. semilaevis. Exposure to PFOS also altered the gene expression levels of hormones (inhibin, insulin, somatostatin, and glucagon), which could lead to severe metabolic and endocrine dysfunction. As expected from previous studies, several phase I and phase II detoxification enzymes were significantly up‐regulated, which could facilitate the biotransformation and detoxification of PFOS in C. semilaevis. The present study provides new insights into the molecular toxicology of PFOS in a commercially important fish species. Environ Toxicol Chem 2020;39:556–564. © 2019 SETAC [ABSTRACT FROM AUTHOR]

Abstract: According to the authors' experience of culturing Half‐smooth Tongue Sole Cynoglossus semilaevis, high stocking densities lead to production failure, but few studies have addressed the problem. The purpose of this experiment was to evaluate the impact of stocking density on the growth and physiological parameters of subadult (700–1,200 g) Half‐smooth Tongue Soles. The experimental design was completely randomized with three replications and one factorial scheme with three stocking densities: low density (LD; 200 fish/tank, 3.51 kg/m2), medium density (MD; 300 fish/tank, 5.30 kg/m2), and high density (HD; 400 fish/tank, 7.06 kg/m2). After 90 d, final mean body weight in the LD group was 1,003.4 g, which was 7.85% higher than that in the HD group. In addition, the activities of digestive enzymes (lipase and amylase) were depressed in the HD group relative to the other groups. Levels of immunology indicators (lysozyme, total superoxide dismutase, catalase, and glutathione peroxidase) were significantly lower in the HD group than in the LD and MD groups. The cortisol concentration was significantly higher in the HD group than in the LD and MD groups. These results show that growth, enzyme activity, and cortisol levels in Half‐smooth Tongue Soles are negatively affected when the fish are cultured at high stocking density. [ABSTRACT FROM AUTHOR]

r-spondin1 ( rspo1) encodes a secreted protein that is involved in the determination and differentiation of the mammalian ovary. However, little information is yet available for teleosts. Here, we identified a homologue of rspo1 in Cynoglossus semilaevis. The full-length cDNA of rspo1 had a length of 2,703 bp with an open reading frame of 834 bp, encoding a protein with a length of 277 amino-acids. rspo1 expression was detected via qRT-PCR in various tissues, and significant sexually dimorphic expression was observed in the gonads. Furthermore, ISH located rspo1 in germ cells such as spermatogonia, spermatocytes, spermatids, spermatozoa, and oocytes, as well as in somatic cells of the gonads. Following knockdown of rspo1 in an ovarian cell line, the expressions of wnt4a, β-catenin, foxl2, and StAR were highly affected; wnt4a and β-catenin were significantly downregulated, whereas foxl2 and StAR were significantly upregulated. In summary, these data suggest that rspo1 may be involved in the regulation of ovarian development and differentiation through a conserved pathway, while the function of the gene in the testis remains elusive. [ABSTRACT FROM AUTHOR]

The indoor recirculating aquaculture system (RAS) is a sustainable alternative to traditional aquaculture systems, and a biofilter is a crucial component for the stable operation of this system. In this study, the bacterial communities within different sections of the biofilter in a full-scale RAS for the culture of Tongue SoleCynoglossus semilaeviswere investigated using polymerase chain reaction–based 454 pyrosequencing. A total of 67,368 effective sequences of the 16S rRNA gene with V1–V3 regions were obtained from samples collected from the front section, rear section, and sludge of the biofilter. Using a 3% cut-off level and sufficient sequencing depth, a total of 5,185 operational taxonomic units (OTUs) were identified in these sequences across all samples. However, a low shared richness of 570 OTUs (11.0% of the reads) was found in all samples, indicating a high diversity of bacterial profiles even in a single biofilter. Based on the SILVA database classifier of phylogenetic taxa, Proteobacteria (average, 35.6%) and Bacteroidetes (average, 30.7%) were found to be the predominant species in all samples, followed by Nitrospirae (6.0%) in the front section, Acidobacteria (7.9%) in the rear section, andPlanctomycetes(9.7%) in the sludge. Overall, 404 genera were assigned to all samples. But among the 10 most common genera, onlyNitrospira,Owenweeksia, andMarinicellawere found in all samples. The results of the phylogenetic analysis suggest that the nitrifying groups of ammonia-oxidizing bacteria belong toNitrosomonasclusters, and the nitrite-oxidizing bacteria are related toNitrospiraandNitrospinaclusters. In summary, our results indicate that the RAS fixed-film biofilter is a highly species-rich ecosystem. For this reason, a potential precision-operated strategy to manage the microbial resources in the biological treatment section in an RAS should be adopted, with consideration being given to the peculiarities and requirements of the species being cultured. Received October 26, 2014; accepted February 5, 2015 [ABSTRACT FROM PUBLISHER]

A new ovarian cell line, CSO, was established from half-smooth tongue sole Cynoglossus semilaevis. Primary culture of CSO cells was initiated from digestion of ovarian tissues pieces by trypsin solution and cultured at 24° C in Dulbecco's modified Eagle's medium- F12 medium ( DMEM- F12, 1:1) (pH 7·0), supplemented with 20% foetal bovine serum, basic fibroblast growth factor ( bFGF), epidermal growth factor ( EGF), insulin-like growth factor-I ( IGF-I) and human chorionic gonadotropin ( HCG). The cultured CSO cells, fibroblastic in morphology, proliferated to 100% confluency 3 days later and had been subcultured to passage 80. Chromosome analyses indicated that the CSO cells exhibited chromosomal aneuploidy with a modal chromosome number of 42 that displayed the normal diploid karyotype of C. semilaevis [2 n = 42 t, fundamental number ( NF) = 42]. Reverse transcription polymerase chain reaction revealed that CSO cells could express ovarian somatic cell functional genes p450 armo, foxl2 and sox9a but not ovary germ cell marker gene vasa and male-specific gene dmrt1. Transfection experiment demonstrated that CSO cells transfected with pEGFP-N3 plasmid could express green fluorescence protein ( GFP) with higher transfection efficiency. The CSO cell line might serve as a valuable tool for studies on the mechanism of sex determination and oogenesis of ovary in flatfish. [ABSTRACT FROM AUTHOR]

The effects of culinary practices such as boiling, frying, and grilling on the proximate compositions and concentrations of metals (Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg) in commonly consumed fish species from the Nigerian coastal waters were investigated. The selected fish species were Polydactylus quadratifilis, Chrysicthys nigrodigitatus and Cynoglossus senegalensis. The culinary practices lead to increased protein, fat, and ash contents and decreased moisture contents of these fish species. The culinary practices resulted significant increase in the concentrations of most of the studied metals and decrease in the concentrations of Fe, Cr, and Pb in some fish types. The concentrations and estimated dietary intakes of Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg from consumption of the processed fish were within their statutory safe limits. The individual metal target hazard quotient ( THQ) values and the total THQs were less than 1 which indicates that no health risks would arise from the long-term consumption of these fish species. [ABSTRACT FROM AUTHOR]

Sixty novel simple sequence repeat (SSR) markers were developed from expressed sequence tags (EST) of half-smooth tongue sole Cynoglossus semilaevis exploited in the laboratory. The number of alleles, observed and expected heterozygosity per locus ranged from two to 16, from 0·0833 to 1·0000 and from 0·0816 to 0·913, respectively. Of these SSRs, 20 had significant homology to known genes by BLASTx (basic local alignment search tool x) search. For cross-species amplification, there are 53 positive amplifications in Japanese flounder Paralichthys olivaceus with 12 polymorphic loci and 51 positive amplifications in Senegalese sole Solea senegalensis with 11 polymorphic loci. These new EST-SSR markers will be useful for genetic studies and genome mapping of C. semilaevis and its closely related fishes. [ABSTRACT FROM AUTHOR]

A central question in ecology concerns how some exotic plants that occur at low densities in their native range are able to attain much higher densities where they are introduced. This question has remained unresolved in part due to a lack of experiments that assess factors that affect the population growth or abundance of plants in both ranges. We tested two hypotheses for exotic plant success: escape from specialist insect herbivores and a greater response to disturbance in the introduced range. Within three introduced populations in Montana, USA, and three native populations in Germany, we experimentally manipulated insect herbivore pressure and created small-scale disturbances to determine how these factors affect the performance of houndstongue (Cynoglossum officinale), a widespread exotic in western North America. Herbivores reduced plant size and fecundity in the native range but had little effect on plant performance in the introduced range. Small-scale experimental disturbances enhanced seedling recruitment in both ranges, but subsequent seedling survival was more positively affected by disturbance in the introduced range. We combined these experimental results with demographic data from each population to parameterize integral projection population models to assess how enemy escape and disturbance might differentially influence C. officinale in each range. Model results suggest that escape from specialist insects would lead to only slight increases in the growth rate (λ) of introduced populations. In contrast, the larger response to disturbance in the introduced vs. native range had much greater positive effects on λ. These results together suggest that, at least in the regions where the experiments were performed, the differences in response to small disturbances by C. officinale contribute more to higher abundance in the introduced range compared to at home. Despite the challenges of conducting experiments on a wide biogeographic scale and the logistical constraints of adequately sampling populations within a range, this approach is a critical step forward to understanding the success of exotic plants. [ABSTRACT FROM AUTHOR]

Three normalized cDNA libraries were constructed, two of which were constructed from reproductive tissues ovary and testis, and the other one from pooled immune tissues including head kidney, intestine, liver and spleen. A total of 10 542 clones were sequenced generating 10 128 expressed sequence tags (ESTs). Cluster analysis indicated a total of 5808 unique sequences including 1712 contigs and 4096 singletons. A total of 4249 (73%) of the unique ESTs had significant hits to the non-redundant protein database, 2253 of which were annotated using Gene Ontology (GO) terms. A total of 311 microsatellites (with 246 having sufficient flanking sequences for primer design) and 6294 putative SNPs were identified. These genome resources provide the material basis for future microarray development, marker validation and genetic linkage and QTL analysis. [ABSTRACT FROM AUTHOR]

Twenty-one microsatellite markers were studied in three meiogynogenetic families of Cynoglossus semilaevis gunther for centromere mapping using half-tetrad analysis. Among the 13 mapped loci, 10 were estimated to be located in the telomeric region, one in the centromeric region, and two in the intermediate region of the chromosome. This study provides a basis for constructing a linkage map of C. semilaevis. [ABSTRACT FROM AUTHOR]

Myeloid differentiation factor 88 (MyD88) is a universal and crucial adaptor protein, which plays an essential role in the intracellular signalling elicited by IL-1R/TLR superfamily. In the present study, we report the full-length sequence of MyD88 gene in half-smooth tongue sole ( Cynoglossus semilaevis). In the 2855 bp genomic sequence, five exons and four introns were identified. The cloned cDNA exhibited 110 bp of 5′ UTR, 576 bp of 3′ UTR and 858 bp of the entire open-reading frame encoding a polypeptide of 285 amino acids. The protein sequence included a typical conserved cytosolic Toll/interleukin-1 receptor (TIR) domain, an intermediate domain (ID) and a death domain (DD), and shared greater than 70% identity with Japanese flounder Paralichthys olivaceu ortholog. Real-time polymerase chain reaction (RT-PCR) analysis indicated a broad expression of csMyD88, especially in ovary and spleen. Quantitative RT-PCR analysis indicated that the csMyD88 mRNA levels were significantly increased in the spleen and head kidney after inactive Vibrio anguillarum challenge and the expression of csMyD88 appeared to be developmentally regulated during C. semilaevis ontogeny. Although, species-specific differences were present, the similarity between mammalian and piscine MyD88s suggested that the main function of MyD88 might be conserved across vertebrates. [ABSTRACT FROM AUTHOR]

Presents information on a study which tested the effect of selective seed abortion on the offspring survival in Cynoglossum officinale. Materials and methods; Results; Discussion.

This paper compares two contrasting biennial plant species of the sand dunes of Holkham, North Norfolk. A survey of distributions in relation to various habitat factors, showed that Lactuca virosa L. is characteristic of the tall, Ammophila-dominated grassland on the younger dunes. It is favoured by gaps in the vegetation cover such as those produced by local wind erosion, but it is very sensitive to rabbit grazing. Cynoglossum officinale L. is a plant of older dune grassland and is not normally grazed by rabbits. It can exploit the bare ground around rabbit warrens, benefiting from the higher nitrogen levels resulting from rabbit excreta. Studies on seed production and germination showed that Lactuca can produce large numbers (> 60000 per plant) of very small (c. 08 mg) wind-dispersed seeds that germinate readily in the autumn. Cynoglossum, on the other hand, produces fewer (< 2500) seeds per plant that are larger (c. 30 mg) and animal-dispersed. Cynoglossum seeds are inherently dormant; most germination is in the late winter and early spring, after a period of cold. Lactuca compensates for small seed size by having a higher growth rate than Cynoglossum as well as by its earlier germination. Despite all these differences, the two species survive at comparable densities. [ABSTRACT FROM AUTHOR]

Eleven polymorphic microsatellite loci have been isolated and characterized from random amplified polymorphic DNA product in half-smooth tongue sole, Cynoglossus semilaevis. Twenty-one microsatellites were selected for designing microsatellite primers, of which 11 gave working primer pairs. They had between three and 12 alleles. Observed and expected heterozygosities varied from 0.53 to 0.93, and from 0.52 to 0.80, respectively. Five additional fish species assessed for cross-species amplification revealed between one and three positive amplifications and between zero and three polymorphic loci per species. [ABSTRACT FROM AUTHOR]

The tongue sole, Cynoglossus semilaevis, is a rare marine flatfish distributed in Chinese coastal waters. From a (GT) n-enriched genomic library, 57 microsatellites were isolated and characterized. Seventeen of these loci were polymorphic in a test population with alleles ranging from three to 13, and observed and expected heterozygosities from 0.1613 to 1.0000 and from 0.2126 to 0.8983, respectively. Five loci deviated from the Hardy–Weinberg equilibrium in the sampled population, and linkage disequilibrium between two loci was significant after applying Bonferroni correction. Three additional fish species assessed for cross-species amplification revealed that only one locus was also polymorphic in one species. These polymorphic microsatellite loci should provide sufficient level of genetic diversity to evaluate the breeding strategy and investigate the fine-scale population structure in C. semilaevis. [ABSTRACT FROM AUTHOR]

Microsatellite markers have been developed from a cDNA library of half-smooth tongue sole, Cynoglossus semilaevis. Twenty-five microsatellites were selected for designing microsatellite primers, of which 11 gave working primer pairs. They had between four and 12 alleles. Observed and expected heterozygosities varied from 0.60 to 0.90 and from 0.57 to 0.88, respectively. Five additional fish species assessed for cross-species amplification revealed between one and four positive amplifications and between 0 and four polymorphic loci per species. [ABSTRACT FROM AUTHOR]