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Intermuscular bones (IBs) are widely present in morphologically generalized teleost fishes and are commonly found in the Cyprinidae. Intermuscular bones are small, hard spicules of bone that are formed by ossification in the myosepta between neighboring myomeres. Why fish have IBs, and whether there is any evolutionary pattern to their occurrence, has been poorly understood. However, the presence of IBs does substantially affect the meat quality and commercial values of many cyprinid fishes in aquaculture. In this study, we sampled 592 individuals of cyprinid fishes to systematically investigate the evolution of IBs from a phylogenetic point of view. We found that the total number of IBs in the Cyprinidae ranged from 73 to 169, and we clarified that only two categories of IBs (epineural and epipleural) were present in all examined cyprinids. Most of the IBs were distributed in the posterior region of the fish, which might be an optimal target for selecting fewer IB strains in aquaculture. There was a positive correlation between IBs and the number of vertebrae, thus making it possible to predict the approximate number of IBs by counting the number of vertebrae. Although the IBs displayed some correlation with phylogenetic relationships in some lineages and to ecological factors such as diet (especially carnivore), in an overall view the variations of IBs in cyprinids were extremely diverse. The number and patterns of IBs in these fishes may reflect their phylogenetic history, but have been shaped by multiple environment factors. In this study, we also confirmed that X‐ray photography remains an optimal and reliable method for the study of IBs.

As one economically important fish in the southeastern Himalayas, the giant devil catfish (Bagarius yarrelli) has been known for its extraordinarily large body size. It can grow up to 2 m, whereas the non-Bagarius sisorids only reach 10–30 cm. Another outstanding characteristic of Bagarius species is the salmonids-like reddish flesh color. Both body size and flesh color are interesting questions in science and also valuable features in aquaculture that worth of deep investigations. Bagarius species therefore are ideal materials for studying body size evolution and color depositions in fish muscles, and also potential organisms for extensive utilization in Asian freshwater aquaculture. In a combination of Illumina and PacBio sequencing technologies, we de novo assembled a 571-Mb genome for the giant devil catfish from a total of 153.4-Gb clean reads. The scaffold and contig N50 values are 3.1 and 1.6 Mb, respectively. This genome assembly was evaluated with 93.4% of Benchmarking Universal Single-Copy Orthologs completeness, 98% of transcripts coverage, and highly homologous with a chromosome-level-based genome of channel catfish (Ictalurus punctatus). We detected that 35.26% of the genome assembly is composed of repetitive elements. Employing homology, de novo, and transcriptome-based annotations, we annotated a total of 19,027 protein-coding genes for further use. In summary, we generated the first high-quality genome assembly of the giant devil catfish, which provides an important genomic resource for its future studies such as the body size and flesh color issues, and also for facilitating the conservation and utilization of this valuable catfish.

In this study, pure‐breeding and crossbreeding of Sinocyclocheilus grahami were established to test heterosis and expression of growth‐related genes which were examined in the first‐generation (F1). Genetic distances results showed that Muyang river (M) and Sanbaimu reservoir (S) populations had smaller interspecific distances (genetic distance: 0.000) while larger distances were shown to other two populations (0.024 of Jiuzhai vauclusian spring [J] and 0.044 of Chenglong vauclusian spring [C]). Full‐sib families were created by using the Muyang river population as females: MM, MS, MJ and MC. Growth performance had significant differences between each group of F1 hybrids; the fastest growth group was shown in MJ while the slowest was in MS. For growth‐related genes, the fast growth group of MJ hybrids showed significantly higher levels of ghrelin expression in strong expression tissues of the intestine and liver. Among the four combinations, mRNA levels of insulin‐like growth factor I (IGF‐I) were the highest expression in MJ hybrids than others in all tested tissues. Myostatin b and somatostatin1 (SST1) were strongly expressed in the brain and MJ hybrids showed relatively lower expression level. In the muscle, slow growth group of MS hybrids showed extremely higher expression levels of these two genes, especially SST1 gene. In conclusion, associating growth with growth‐related genes expression indicated faster growth of crossbreeding in S. grahami and can make a contribution to commercial fish production in the future.

Steam generator blowdown (APG) system is a very important system for the steam generator water purification in PWR. However, the frequently exceeded pressure drop of resin bed in the APG system may cause excessive steam generator blowdown cut-off, or blowdown rate reducing, so that the steam generator water cannot be purified in optimization approach. At the same time, the real exceeded pressure drop of resin bed may also lead to the broken of resin, and then pollute the secondary water and block the related equipment of secondary cycle. So, these issues always bother the safety and stability of the system in operation. The frequent replacement of resin bed will increase unnecessary solid waste and economic losses. In order to find the main reasons for the frequently exceeded pressure drop of resin bed, the resin pressure drop in power station, the secondary water chemistry, the theoretical calculation for pressure drop, the deigned device structure and parameters, and the online instrument failure were be analyzed in this paper. After the theoretical analysis and the maintenance of resin bed during the outage, the main reasons for the frequently exceeded pressure drop of resin bed were be found, the blocked water cap of the resin bed.

In order to obtain reliable results of gene expression, appropriate internal control gene(s) were required for normalization before real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Here, we selected eight candidate housekeeping genes as the potential reference genes in normalizing qRT-PCR data in ten tissues of the juvenile and adult stages of a naturally tetraploid cyprinid fish Sinocyclocheilus grahami. Before qRT-PCR, appropriate primers were designed and compared for distinguishing different copies in some duplicate genes. Candidate reference genes were evaluated for their stability using online software RefFinder, which is integrated by four normal software of the comparative delta-CT, BestKeeper, NormFinder and GeNorm. According to the rankings produced by these analyses, Eef2, ACTB and G6PD were the most stable reference genes as internal controls for qRT-PCR in juvenile, while B2M, Eef2 and RPL17 were shown to be most appropriate in adult fish. All the analyses show that GAPDH was the least stable expression gene which would be unsuitable as reference gene at both stages. This is the first report about reference gene selection in Sinocyclocheilus and we think that is beneficial for the future gene expression studies in golden-line barbel.

Body size is one of the most important attributes of a species, but the basic question of why and how each species reaches a different &ldquo, right size&rdquo, is still largely unknown. Herein, three phylogenetically closely related catfishes from Sisoridae, including one extraordinarily large-sized Bagarius yarrelli and two average-sized Glyptothorax macromaculatus and Oreoglanis setiger, were comparatively studied using RNA-Seq. Approximately 17,000 protein-coding genes were annotated for each of the three fishes, and 9509 genes were identified as high-confidence orthologous gene pairs. Comparative expressions uncovered a similar functional cluster about ribosome biogenesis was enriched in different tissues of the upregulated genes of Bagarius yarrelli. Moreover, differentially expressed genes and positively selected genes revealed that the glycolysis/pyruvate metabolism and cell cycle pathways have also greatly enhanced in this large-sized species. In total, 20 size-related candidate genes (including two growth modulators: the serine/threonine-protein kinases 3 (AKT3) and adaptor protein 1 (SH2B1), and a crucial pyruvate kinase (PKM2A)) were identified by multiplying comparative analyses along with gene functional screening, which would play major roles in enabling the large body size associated with Bagarius yarrelli and provide new insights into body size evolution. In conjunction with field observations and morphological comparisons, we hypothesize that habitat preferences promote size divergence of sisorids.

The wild Porphyra yezoensis collected from the Qingdao coast was used to prepare protoplasts by enzyme digestion. The pure line was constructed by cultivating the protoplasts. The 18S rDNA of the P. yezoensis pure line was cloned and sequenced. Sequence analysis was executed for this sequence and other 22 sequences retrieved from GenBank. A phylogenetic tree was constructed using the neighbor-joining method. The results revealed a high diversity of 18S rDNA sequences in genus Porphyra and the considerable variation of 18S rDNA sequences in different strains of the same species P. yezoensis and P. tenera. Significant difference of 18S rDNA sequence was observed between P. yezoensis from Qingdao, China, and the two strains of P. yezoensis from Japan, but the three strains of P. yezoensis formed a stable clade in the phylogenetic tree. These results indicate the possibility of interspecies and intraspecies discrimination of Porphyra using the 18S rDNA sequences.

Protoplasts of Porphyra yezoensis were successfully cryopreserved at liquid nitrogen (LN) temperature by vitrification and subsequently regenerated into plants. The effects of different vitrification solutions, loading and dehydration time, and thawing condition on protoplasts viability after cryopreservation were evaluated. VS6 (10% w/v dimethyl sulfoxide (DMSO), 30% w/v glycerol, 10% sucrose in seawater) seems to be a preferable vitrification solution for P. yezoensis protoplasts. The best vitrification protocol using VS6 involves: loading with 25% VS6 for 5 min at 0 °C, dehydrating with ice-cold concentrated VS6 for 3 min, immediately immersing in LN, and then warming in 40 °C water bath. Using this protocol, P. yezoensis protoplasts showed higher viability (66.5%) after cryopreservation. Although the regrowth of cryopreserved protoplasts showed a 2–3-day lag phase and recovered completely until 20 days after thawing, the growth pattern was the same as that of non-cryopreserved protoplasts. In summary, we have developed a new method for the cryopreservation of P. yezoensis protoplasts, which allows long-term maintenance of valuable genotypes.

In order to test whether 18S rDNA can influence positively GUS gene transient expression in the red alga Porphyra yezoensis, a targeting vector pQD-GUS was constructed containing a portion of the 18S rDNA of P. yezoensis and transformed it into the same strain protoplasts. The results showed that GUS protein activity was increased markedly with pQD-GUS compared to the parent pBS-GUS. It is suggested that this system can be used to enhance the expression of exogenous genes in transgenic P. yezoensis.

The catfish genus Pseudexostoma (Sisoridae) currently contains three species: P. yunnanensis from the upper Irrawaddy River (Dayingjiang), and P. brachysoma and P. longipterus from the upper Salween River (Nujiang). We adopted an integrative approach combining both morphology-based (traditional measurements, truss-based and geometric morphometrics, fin skeleton examination and X-ray photography) and molecular approaches (genetic distances, haplotype network, phylogenetic relationships) to reappraise species validity in Pseudexostoma . Our results showed that P. longipterus cannot be distinguished from P. brachysoma from either morphological or molecular analyses, and that the former name should thus be considered a junior synonym of the latter. The two remaining geographically isolated species, P. yunnanensis and P. brachysoma , showed a distinct genetic distance equated to the typical 2% sequence divergence threshold delineating different species of fishes, and with a divergence time dated to approximately 1.22–2.14 million years ago. Although P. yunnanensis and P. brachysoma share some morphological characters that appear gradually diverging (body depth at anus and interorbital distance), some degree of overlap still exists, we suggest the two species are distinct based on the total evidence.

Monocrotophos (MCP) is an organophosphorus pesticide moderately toxic to fish, and it has significant estrogenic properties in vivo. In this study, zebrafish (Danio rerio) were exposed to 0.001, 0.010, and 0.100 mg/L 40% MCP pesticide in a semi-static manner from fertilization to 40 days post-hatching. Histological analyses were performed to determine whether sex differentiation in zebrafish was affected by MCP, and the mRNA expression levels of genes involved in sexual differentiation were quantified by real-time PCR to clarify the possible mechanism(s) of action. The results revealed a prominent increase in the proportion of females (71%) in the 0.100 mg/L MCP pesticide treatment as well as the presence of one intersex individual in each of the groups exposed to 0.001 and 0.100 mg/L MCP. MCP exposure stimulated forkhead transcription factor gene L2 (foxl2) expression and suppressed doublesex/mab-3 related transcription factor 1 (dmrt1) expression, indirectly leading to elevated gonadal aromatase (cyp19a1a) gene expression, which should promote phenotypic feminization. In addition, MCP treatment increased the transcription of brain aromatase (cyp19a1b), resulting in an indirect impact on sexual differentiation. The results from this investigation can be used for risk and hazard assessment of MCP pesticide.