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Swimming performance is viewed as a vital characteristic determining survival in many fish in the natural environment. However, a growing number of studies show that swimming exercise of cultivable fish has been associated with improved flesh quality, to which consumers are paying increasing attention. It includes a variety of aspects with both biological and edible layers. In the current situation, aquaculture in flowing water as an effective and feasible alternative for flesh quality improvement has a promising prospect. The goal of this review is to highlight key studies that have contributed to the influence of swimming exercise on fish growth performance, fibretype composition, nutritional value and muscular sensory properties, and tries to reveal the underlying mechanisms of flesh quality improvements. In addition, the issues that need to be highly valued in the application of flowing water to aquatic production practices are pointed out. [ABSTRACT FROM AUTHOR]

Obtaining oocytes from the adult female zebrafish (Danio rerio) ovary has enormous importance in the studies of developmental biology, toxicology, and genetics. It is vital to establish a simple and effective approach to ensure the quantity and quality of oocytes, which will enable the success of follow‐up experimental investigation finally. Usually, oocytes are separated with mechanical or enzymatic methods, however, little studies have been done with concerns about the comparative effects. The present study separated zebrafish oocytes of Stage III with five frequently used methods, including stripping, pipetting, hyaluronidase (1.6 mg/ml), collagenase (0.4 mg/ml), and trypsin (0.1%). The cell viability, oxidative stress, mitogen‐activated protein kinase (MAPK) protein phosphorylation, and apoptosis levels were selected as main biomarkers to evaluate the oocytes health status. The results showed that both trypsin and hyaluronidase isolation significantly upregulated germinal vesicle breakdown (GVBD) rates and downregulated p38 MAPK activity simultaneously. GVBD rates and survival rates were decreased notably in oocytes separated by the collagenase method. Above results indicate that zebrafish oocytes in vitro are sensitive to enzymatic treatments and the enzymatic isolation is not the suitable mean for collecting zebrafish oocytes although it is time‐saving. The mechanical strategy of pipetting remarkably increased the reactive oxygen species and malondialdehyde level in isolated oocytes. Interestingly, oocytes separated with stripping show less physiological and biochemical damages. Therefore, stripping isolation is comparatively recommended as the optimum method for separating and collecting numerous intact and healthy zebrafish oocytes in vitro for the subsequent developmental research. Obtaining oocytes from the adult female zebrafish (Danio rerio) ovary has enormous importance in the studies of developmental biology, toxicology, and genetics. It is vital to establish a simple and effective approach to ensure the quantity and quality of oocytes, which will enable the success of follow‐up experimental investigation finally. Usually, oocytes are separated with mechanical or enzymatic methods, however, little studies have been done with concerns about the comparative effects. [ABSTRACT FROM AUTHOR]

The critical period of ammonia volatilization (AV) is an important indicator in the development of control measures of AV. A field trial was performed for 2-yr with zero-N fertilization control (CK), controlled-release-urea (CRU), and urea in rice (Oryza sativa L.)-wheat (Triticum aestivum L.) rotation system to investigate AV. The N application dosage was 255 and 225 kg N ha-1 in rice and wheat season, respectively. The CRU was applied once as basal fertilization in each growing seasons. Urea was applied twice in the rice season, while it was applied three times in the wheat season. The results revealed that AV applied with urea was 61.4 and 57.3% higher than that with CRU in 2010-2011 and 2011-2012, respectively. The AV applied with CRU and urea predominately occurred at the rice flooding period, which accounted for 83.2 to 86.6% and 95.5 to 96.9% of AV at the entire rice season and for 48.2 to 49.6% and 67.2 to 70.4% of AV in the rice-wheat rotation period, respectively. No obvious difference was observed between urea and CRU treatments concerning grain yield, N concentration, and removal N of aboveground biomass. An obvious influence of rainfall on AV was documented because rainfall significantly reduced AV during the rice growth, while the rainfall before N fertilization could significantly increase AV in the wheat season. Therefore, the rainfall should be considered when applying N fertilizer, CRU should be recommended to use during the rice flooding period to decrease the AV rate. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) play important roles in mediating multiple biological processes in eukaryotes and are being increasingly studied to evaluate their roles associated with cellular changes following viral infection. Snakehead fish Vesiculovirus (SHVV) has caused mass mortality in snakehead fish during the past few years. To identify specific miRNAs involved in SHVV infection, we performed microRNA deep sequencing on a snakehead fish cell line (SSN-1) with or without SHVV infection. A total of 205 known miRNAs were identified when they were aligned with the known zebrafish miRNAs, and nine novel miRNAs were identified using MiRDeep2 software. Eighteen and 143 of the 205 known miRNAs were differentially expressed at three and 24 h post-infection (poi), respectively. From the differentially-expressed miRNAs, five were randomly selected to validate their expression profiles using quantitative reverse transcription polymerase chain reaction (qRT-PCR), and their expression profiles were consistent with the microRNA sequencing results. In addition, the target gene prediction of the SHVV genome was performed for the differentially-expressed host miRNAs, and a total of 10 and 58 differentially-expressed miRNAs were predicted to bind to the SHVV genome at three and 24 h poi, respectively. The effects of three selected miRNAs (miR-130-5p, miR-214 and miR-216b) on SHVV multiplication were evaluated using their mimics and inhibitors via qRT-PCR and Western blotting. The results showed that all three miRNAs were able to inhibit the multiplication of SHVV; whereas the mechanisms underlying the SHVV multiplication inhibited by the specific miRNAs need to be further characterized in the future. [ABSTRACT FROM AUTHOR]

Snakehead fish vesiculovirus (SHVV) is a negative strand RNA virus which can cause great economic losses in fish culture. To facilitate the study of SHVV-host interactions, the susceptibility of zebrafish embryonic fibroblast cell line (ZF4) to the SHVV was investigated in this report. The results showed that high amount of viral mRNAs and cRNAs were detected at the 3 h post-infection. However, the expressions of the viral mRNAs and cRNA were decreased dramatically after 6 h post-infection. In addition, the expressions of interferon (IFN) and interferon-induced GTP-binding protein Mx were all up regulated significantly at the late stage of the infection. Meanwhile, the expressions of Retinoic acid-inducible gene I (RIG-I) and Melanoma differentiation-associated gene 5 (MDA5) were also all up-regulated significantly during the infection. Two isoforms of DrLGP2 from zebrafish were also cloned and analyzed. Interestingly, the expression of DrLGP2a but not DrLGP2b was significantly up-regulated at both mRNA and protein levels, indicating that the two DrLGP2 isoforms might play different roles during the SHVV infection. Transfection experiment showed that viral replicative intermediates were required for the activation of IFN-α expression. Taken together, the abortive infection of SHVV in ZF4 cells was associated with the activation of RLRs pathway, which was activated by viral replicative intermediates. [ABSTRACT FROM AUTHOR]

Highlights: • The first time to consider the potential health risk for consuming fish head. • Fish head poses a higher potential risk than both ventral muscle and dorsal muscle. • The fat was separated and the chromium contents in it were extremely low. • The accumulation of chromium was not associated with fat. Abstract In this study, bighead carp (Aristichthys nobilis) were exposed to waterborne Cr6+ of 0.01, 0.1, 1 and 5 mg/L for 14 days and subsequently transferred to clean water for another 14 days. The Cr6+ contents in some edible parts, such as dorsal muscle, ventral muscle and head were detected. The Cr6+ concentrations in the three parts were in the order of: head > ventral muscle > dorsal muscle with significant increase during exposure period and remarkable decrease when kept at clean water during depuration stage. The head contained higher fat than that of muscle and the Cr6+ levels of these parts showed significantly positive correlation with fat content, however, the Cr6+ contents in the separated fat were extremely low. The Cr6+ levels determined in tissues can tell a real story rather than the correlation coefficient. Fish head poses a higher potential health risk than muscle due to heavy metals pollution. [ABSTRACT FROM AUTHOR]