Pelteobagrus Fulvidraco Research Articles

Effects of dietary protein level on the growth, reproductive performance, and larval quality of female yellow catfish (Pelteobagrus fulvidraco) broodstock

This study was conducted to evaluate the effects of dietary protein levels on the growth, spawning, and larval quality of female yellow catfish (Pelteobagrus fulvidraco) broodstock through a six-week feeding trial. Five isoenergetic diets were formulated, and the crude protein levels were 34.4 (DP34), 38.8 (DP39), 44.2 (DP44), 49.3 (DP49), and 52.7% (DP53). The results showed that the growth and reproductive performance, including the specific growth rate (SGR), feed efficiency (FE), gonadosomatic index (GSI), and hatching rate of yellow catfish broodstock in the DP44, DP49, and DP53 groups were significantly higher than those of other groups (P < 0.05). The optimal dietary protein levels for yellow catfish broodstock were 45.8% and 44.1% based on SGR and GSI. The lowest condition factor (CF), GSI, and smallest egg size were found in the DP34 group, while the total egg production was the highest in the DP53 group. Vitellogenin (VTG) contents in eggs and plasma were enhanced significantly with the increasing dietary protein levels from 34% to 49%, but decreased precipitously in the DP53 group (P < 0.05). The optical densities of androgen receptor (AR) and estrogen receptor (ER) in the DP34 group were significantly lower than those in other groups. The mRNA expression levels of CYP19a, AR, and ERβ were significantly increased in the DP49 group (P < 0.05). For larval quality, the deformity rate decreased significantly with the increasing dietary protein levels (P < 0.05). The larval survival rate at 9 DPH (days post-hatching) as a function of dietary protein level was analyzed by second-order polynomial regression. The results showed that a level of 47.7% was optimal for improving larval quality. Thus, a suitable range of dietary protein of yellow catfish broodstock for growth and reproduction is 44.1–47.7%.

Induction of meiotic gynogenesis in Lanzhou catfish ( Silurus lanzhouensis ) with heterologous sperm and evidence for female homogamety

As a critical factor in the sustainability of fisheries, gynogenesis can be used to provide a shortcut for the genetic improvement of the endangered and degraded germplasm resources of the important Yellow River fish Silurus lanzhouensis. In this study, ultraviolet-inactivated yellow catfish Pelteobagrus fulvidraco sperm were used to induce meiotic gynogenesis in S. lanzhouensis through cold shock, and the optimal conditions for the genetic inactivation of the sperm and cold shock treatment were selected. Using microsatellite markers and gonadal histology, the genetic purity and sex determination of the gynogenetic offspring of S. lanzhouensis were analysed. The optimal induction conditions were as follows: treatment with P. fulvidraco sperm with 107- µW/cm2 ultraviolet irradiation for 30 min, fertilization of S. lanzhouensis eggs for 6 min and subsequent cold shock treatment at 4–6°C for 25 min. Flow cytometry and microsatellite markers confirmed the successful induction of meiogynogenesis. The homozygosity of the gynogenetic group (0.63) was higher than that of the normal control group (0.32). The sex ratio was determined through gonad histological observations, and 100% of the offspring in the gynogenetic groups were female, strongly indicating that the sex determination system of S. lanzhouensis is the XX/XY-type. In this study, inactivated heterologous sperm were used to successfully obtain meiogynogenetic individuals of S. lanzhouensis, and the study provides an important basis for the establishment of a pure line of these endangered fish and sex-controlled breeding of S. lanzhouensis.

Characterization of immunomodulatory lncRNAs in the head kidney of yellow catfish (Pelteobagrus fulvidraco) infected by Aeromonas hydrophila

As molecular mediators, long noncoding RNAs (lncRNAs) are essential for multiple biological processes, such as activating immune response genes and regulating the inflammatory process. The draft genome has been sequenced in yellow catfish (Pelteobagrus fulvidraco), but the expression profile and role of lncRNAs in this fish are still unclear. To identify the immunity-associated lncRNAs in the head kidney of yellow catfish, lncRNA sequences were acquired after Aeromonas hydrophila infection. After high-throughput sequencing, 202 differentially expressed lncRNAs were obtained, including 131 upregulated and 71 downregulated lncRNAs. The functional annotation of cis- and trans-regulatory target genes revealed that many DE-lncRNAs were involved in multiple immunity-associated GO terms and KEGG pathways, such as C-C motif chemokine 3 and interferon regulatory factor 1. Moreover, some lncRNAs might give rise to miRNA. The present study not only revealed the immunomodulatory lncRNAs in head kidney, but also provided a new perspective on the immune response mechanism. The results will facilitate subsequent studies in this species.

Edwardsiella ictaluri: A systemic review and future perspectives on disease management

AbstractEdwardsiella ictaluri, a non‐zoonotic Gram‐negative bacterium, has been known to science for more than 4 decades. It was reported for the first time in 1979 in Ictalurus punctatus in the USA and later in Pangasianodon hypophthalmus and Pelteobagrus fulvidraco in Asia. Even though catfish species are more susceptible to E. ictaluri, other fish species are also affected, and up to 44 fish species in four continents are known to be susceptible. The diseases caused by E. ictaluri are known as enteric septicaemia of catfish (ESC) in channel catfish, bacillary necrosis of pangasius (BNP) in striped catfish, red head disease in yellow catfish and edwardsiellosis in tilapia. Outbreaks caused by E. ictaluri can cause up to 100% mortality resulting in substantive economic losses to the industry, threatening food security and undermining sustainability. Although efforts have been made to prevent and control this pathogen using vaccines, antibiotics, disease resistance selective breeding, functional feed ingredients, prebiotics and probiotics, and biosecurity measures, E. ictaluri is still causing health issues in different countries. Here, we provided with a comprehensive review that addressed the current knowledge of E. ictaluri bacteriological characteristics, epidemiology, pathogenesis, diagnosis, control and management. Furthermore, we also provided the future perspectives based on advanced technologies and biosecurity management in aquaculture to assist pathogen control and/or eradication.

Determination of doxycycline’s plasma protein binding rates in the plasma of grass carp ( Ctenopharyngodon idella ), yellow catfish ( Pelteobagrus fulvidraco ) and crayfish ( Procambarus clarkii ) by an ultrafiltration method at different temperatures with different concentrations

The objective of this study was to compare the plasma protein binding rates (PPBRs) of doxycycline (DC) in the plasma of grass carp (Ctenopharyngodon idella), yellow catfish (Pelteobagrus fulvidraco) and crayfish (Procambarus clarkii) at different temperatures (4, 18 and 25℃) with different concentrations (1, 5, 10 and 20 μg/ml). A rapid and simple method of ultrafiltration (UF) was employed to determine the PPBR of DC in the plasma. The results showed that PPBRs were increased with the rise of the concentration of DC at the same temperature. At 4 ℃, PPBRs were increased from 90.00% to 99.51%, 89.81% to 98.71% and 84.08% to 99.21% in the plasma of grass carp, yellow catfish and crayfish respectively. At 18℃ and 25℃, the same trend was also presented in the three species. Meanwhile, PPBRs of DC might have the atypical nonlinear phenomenon. Otherwise, the temperature could affect the PPBR of DC at a certain degree in the plasma of grass carp and yellow catfish at the same concentration of DC. However, no regularity was presented in the plasma of crayfish. Overall, the increased concentration of DC significantly affected the PPBR in the plasma of grass carp, yellow catfish and crayfish at the same temperature, but the temperature only had a certain influence on the PPBR of grass carp and yellow catfish. Hence, this study is beneficial to design suitable therapeutic regimens and formulations of DC in grass carp, yellow catfish and crayfish at different temperatures.

A high-fat diet alters lipid accumulation and oxidative stress and reduces the disease resistance of overwintering hybrid yellow catfish (Pelteobagrus fulvidraco♀×P. vachelli♂)

This study was carried out to investigate the influence of dietary lipid levels on the growth, immune response, and disease resistance of hybrid yellow catfish (Pelteobagrus fulvidraco♀×P. vachelli♂) during overwintering. Yellow catfish (initial body weight: 49.42 ± 1.33 g) were fed isonitrogenous diets (crude protein 40%) with three lipid levels (low lipid: 8.57%, medium lipid: 12.65%, and high lipid: 16.60%) for five weeks before the overwintering stage, and then all fish were fasted during overwintering. After overwintering, a bacterial challenge test was performed. The results showed that dietary lipid levels had no influence on the growth of hybrid yellow catfish before or after overwintering, but the high lipid (16.60%) diet significantly reduced the survival rate of the fish after bacterial challenge (P < 0.05). Crude whole-body fat content in each treatment after overwintering was significantly lower than that before overwintering. In addition, the liver lipid content significantly increased with increasing dietary lipid levels (P < 0.05). Before overwintering, expression levels of genes related to lipogenesis and lipolysis pathways in liver tissue were down-regulated by the 16.6% lipid diet (P < 0.05). Plasma superoxide dismutase (SOD) activities and malondialdehyde (MDA) contents were enhanced with the increase of dietary lipid level before the challenge test. Plasma SOD activities and MDA contents were significantly decreased in the high lipid group, and plasma cortisol content and lysozyme (LYZ) activity in the 16.60% lipid group were significantly higher than those in the 8.57% lipid group (P < 0.05) at 12-h post bacterial challenge. The mRNA expression levels of toll-like receptor 2 (tlr2) in spleen post-challenge were significantly downregulated compared to pre-challenge (P < 0.05). The transcriptional levels of interleukin 1β (il-1β), tumor necrosis factor α1 (tnfα1), interleukin 10 (il-10), and immunoglobulin M (igm) in spleen or kidney were significantly increased post-challenge compared to pre-challenge, and the relative expression levels of immune-related genes in the high lipid group were greater than those of the low lipid group post-challenge (P < 0.05). The results indicated that high dietary lipid (16.60%) induces oxidative stress and reduces disease resistance of hybrid yellow catfish through a pathway involving regulation of tlr and the inflammatory response during overwintering.

Fishery Status and Rebuilding of Major Economic Fishes in the Largest Freshwater Lake in China Based on Limited Data

Poyang Lake, the largest freshwater lake in China, possesses abundant fishery resources, but its fish stock status is still unclear. In this work, the stock status of and fishing efforts of nine major economic fishes in the Poyang Lake were estimated from 2000 to 2019 with a catch-based maximum sustainable yield (CMSY) model based on catch and resilience data. It was further predicted whether the biomass of those fishes could be restored to support maximum sustainable yield (Bmsy) under the policy of “Ten years fishing moratorium in the Yangtze River”. The results showed that goldfish Carassius auratus, grass carp Ctenopharyngodon idella, and black carp Mylopharyngodon piceus suffered from higher fishing efforts and low biomass in the past 20 years; bighead carp Hypophthalmichthys nobilis, yellow catfish Tachysurus fulvidraco, and common carp Cyprinus carpio responded differently to their fishing efforts; silver carp Hypophthalmichthys molitrix, Amur catfish Silurus asotus, and mandarin fish Siniperca chuatsi were underexploited. Six species were overfished in 2019, and their biomass would be expected to recover for sustainable exploitation during the fishing moratorium, except for M. piceus. This study provided a case study of feasible freshwater fishery evaluation in limnetic ecosystems.

Water quality, plankton composition, and growth performance of juvenile yellow catfish (Pelteobagrus fulvidraco) in mono- and polyculture systems

Polyculture systems have been used to increase the production of yellow catfish (Pelteobagrus fulvidraco), an important aquaculture species; however, detailed comparative analyses of polyculture and monoculture systems in ponds are lacking. In this study, an 84-day experiment was conducted to compare the water quality, plankton composition, and growth performance of juvenile yellow catfish in mono- and polyculture systems. Three treatments were assessed in nine earthen ponds of 0.6–0.7 ha, including yellow catfish monoculture (T1), yellow catfish and grass carp polyculture (T2), and yellow catfish, grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), and bighead carp (Hypophthalmichthys nobilis) polyculture (T3). In general, the concentrations of dissolved oxygen in the T3 treatment were significantly higher than those in the other treatments (P < 0.05). The contents of total ammonia nitrogen, nitrite nitrogen, total suspended solids, and chemical oxygen demand in T3 were significantly lower than those in T1 (P < 0.05). The contents of nitrate nitrogen, orthophosphate, and chlorophyll a (Chl-a) in T3 were significantly lower than those in T1 and T2 (P < 0.05). The water temperature (WT), transparency, and pH values did not differ significantly among treatments (P > 0.05). The biomass of zooplankton and phytoplankton was high in T2 and low in T3, and there were significant positive correlations between biomass and both WT and Chl-a concentrations. Regarding growth and yield parameters, the survival rates of yellow catfish did not differ significantly among treatments (P > 0.05). The final body weight, weight gain, species-specific productivity, and total productivity in T3 were significantly higher (P < 0.05) than those of T1 and T2. The specific growth rates in T3 and T1 were significantly higher than those in T2 (P < 0.05). Our results suggest that polyculture of yellow catfish with grass carp, silver carp, and bighead carp is a promising method owing to its ecological and economic benefits.

Characterization, expression, and function analysis of AKR1A1 gene from yellow catfish (Tachysurus fulvidraco).

Aldehyde reductase (AKR1A1) is a carbonyl detoxification protein in toxic aldehyde removal. In the present study, the full-length cDNA of yellow catfish AKR1A1 (TfAKR1A1) was cloned. As expected, yellow catfish AKR1A1 showed similarities with that of other species. Subsequently, prokaryotic expression vector was constructed and recombinant TfAKR1A1 (rTfAKR1A1) was successfully induced and purified. rTfAKR1A1 exhibited reductive activity to many aldehydes and ketones. To determine whether TfAKR1A1 could confer stress tolerance in vitro, the viability of control and TfAKR1A1 expression E. coli under abiotic stress was compared by spot assay. Results showed that the recombinant strain had better stress resistance under cadmium, hydrogen peroxide, and DL-glyceraldehyde stress. Then, effects of an intraperitoneal injection of rTfAKR1A1 protein on cadmium-induced oxidative stress were evaluated. Results displayed that TfAKR1A1 and Nrf2 expression levels were significantly decreased, CAT and SOD expression levels were significantly increased, BCL-2 and IL-10 expression levels were significantly increased, and caspase3a, NF-κB, and IL-1β expression levels were significantly decreased in protein-injection group. Furthermore, oxidative stress indexes in livers under different protein injection doses were examined by ELISA. Results showed that CAT, SOD, and GSH-Px activities were upregulated, ROS and T-AOC contents were also improved, while MDA content was significantly decreased both in lower and middle dose injection groups. Finally, liver pathological section analysis was performed. Results displayed that liver injury degree in protein-injected groups was lower than that of PBS group under cadmium stress. These results suggested that TfAKR1A1 played important roles in response to cadmium stress in yellow catfish.

Rapid detection of Edwardsiella ictaluri in yellow catfish (Pelteobagrus fulvidraco) by real-time RPA and RPA-LFD

Yellow catfish (Pelteobagrus fulvidraco) is an important freshwater cultured fish in China. Enteric septicemia of catfish (ESC) and red-head disease (RHD), caused by Edwardsiella ictaluri, result in huge economic losses to yellow catfish farming industry. Rapid and handy detection of E. ictaluri is a pressing demand for diagnosis. In this study, we developed rapid, convenient, sensitive and accurate detection methods RPA (recombinase polymerase amplification), real-time RPA (based on real-time fluorescent detection) and RPA-LFD (combining RPA with lateral flow dipsticks (LFD)), targeting the conserved sequence of serC gene in E. ictaluri. The RPA-LFD and real-time RPA methods could achieve detection within 30 min at 38 °C. All the three methods had high analytical sensitivity (102 copies/μl) and were 10 times more sensitive than that in general PCR. They were highly specific for identification of E. ictaluri. 24 samples of yellow catfish from farm were examined through RPA, real-time RPA and RPA-LFD methods, the results showed the consistency with the general PCR detection. In short, RPA, real-time RPA and RPA-LFD methods characterize rapid, simple, sensitive and accurate detection and demonstrate great potential for diagnosis of E. ictaluri disease in fish farms.

Molecular characterization, expression and function analysis of interleukin-17B, C and D genes in yellow catfish (Pelteobagrus fulvidraco)

In mammals, Interleukin-17B, C and D (IL-17B, C and D) play critical roles in the inflammatory responses. In fish, IL-17C and D have been found in various species, and IL-17B has only been reported in channel catfish, but there is little information about the functional activities of IL-17B, C and D in fish. In this study, the protein structure and exon length of Pf_IL-17B, C and D genes in yellow catfish (Pelteobagrus fulvidraco) were similar to those of mammalian IL-17B, C and D, implying that the IL-17B, C and D in fish may have similar bioactivities to those in mammals. Moreover, NJ phylogenetic tree and syntenic analysis showed that the IL-17B, C and D genes were highly conserved in tetrapods, but the IL-17B gene was lost in some teleosts. Pf_IL-17B, C and D genes were highly expressed in blood and gonad from healthy yellow catfish. After infection with Edwardsiella ictaluri, Pf_IL-17C and D transcripts were notably up-regulated in all six tissues and five tissues (except skin) detected, respectively, whereas Pf_IL-17B transcript was only markedly up-regulated in the gill. Moreover, lipopolysaccharides (LPS), polyinosinic-polycytidylic acid (Poly I:C), peptidoglycan (PGN), and phytohaemagglutinin (PHA) distinctly induced the expressions of Pf_IL-17B, C and D mRNAs in the isolated peripheral blood leucocytes (PBLs) of yellow catfish. These results reveal that Pf_IL-17C and D genes may play more important roles than Pf_IL-17B in the immunoregulation against pathogens. Moreover, recombinant (r) Pf_IL-17B, C and D proteins could remarkably induce the expressions of inflammatory cytokines, chemokines and antimicrobial peptide genes mRNAs in the PBLs and gill leukocytes (GLs), and they also notably promoted the phagocytosis and chemotaxis of the PBLs. Besides, the rPf_IL-17B, C and D proteins could induce ACT1, TRAF6, TAK1, IKKα, NFκB1 and NFκB2 mRNAs to activate the NF-κB and p38 MAPK signal pathways. These results uncover that the Pf_IL-17B, C and D genes may mediate inflammatory response to eliminate invasive pathogens.

Characteristics and differences of microplastics ingestion for farmed fish with different water depths, feeding habits and diets

Microplastics have become a potential hazard to the quality and safety of aquatic products although there are few reports on microplastics distribution related to water depth, feeding habits and diets in aquaculture ponds. In this study, five aquaculture fish species (Ctenopharyngodon idella, Hypophthalmichthys molitrix, Cirrhinus molitorella, Oreochromis niloticus and Pelteobagrus fulvidraco) were selected and their accumulation of microplastics was measured and classified. We found that the water depth, feeding habits and diets led to large differences in microplastics accumulation. The bottom-dwelling omnivorous fish had the largest ingestion of microplastics and ranked as P. fulvidraco>O. niloticus>C. molitorella，the herbivore C. idella in the middle benthic layer and the upper-layer filter-feeder H. molitrix had the lowest ingestion. The detection frequency in the gastro-intestinal tracts for C. idella, H. molitrix, C. molitorella, O. niloticus, and P. fulvidraco were 93.33%, 91.67%, 87.50%, 92.86%, and 90.91%, and detection frequencies for gills were 86.67%, 100%, 87.5%, 100%, and 81.82%, respectively. Fibers presented the dominant shape (91.92%) and blue was the primary particle color in the majority of the samples (77.39%) and 0.5–2 mm particles dominated. The plastics were composed of olefins, acrylic, rayon, polyester, polyethylene and polypropylene. Our study first reported the relationship between MPs accumulation and water depth, feeding habits and diets in aquaculture ponds, which also has a certain correlation with the fish size.

Rapid determination of antiviral drugs in yellow catfish (Pelteobagrus fulvidraco) using graphene/silica nanospheres (G/KCC-1) based pipette tip solid-phase extraction with ultra-performance liquid chromatography-tandem mass spectrometry

Yellow catfish (Pelteobagrus fulvidraco) is commonly contaminated by protease inhibitors because of the illegal use of antiviral drugs in aquaculture, so the determination of antiviral drugs is essential in food safety supervision. In this study, a novel sorbent, graphene and silica nanospheres composite (G/KCC-1), was synthesized for pipette-tip-based solid-phase extraction (PT-SPE) and purification of ritonavir, saquinavir, and indinavir in yellow catfish, followed by ultra-performance liquid chromatography and tandem mass spectrometry (UPLC-MS/MS) analysis. The wrinkly structure of G/KCC-1 with center-radial nanowrinkles enlarged the surface area and increased the capacity of absorbing the target analyte. With the proposed G/KCC-1 based PT-SPE UPLC-MS/MS method, the pH of sample solution, aspirating/dispensing cycles for extraction and elution were optimized to be 4.0, 25, and 10 respectively, and the eluting solvent was methanol/ammonia (95:5, v/v) with 0.02 M sodium chloride. This new method was further validated to be linear (correlation coefficient R2, 0.9993–0.9996), sensitive (limit of detection, LOD ≤ 0.8 ng mL−1), accurate (89.3–114.2%), and precise (relative standard deviation, RSD ≤ 6.23%). These results indicated that the proposed method is qualified in bioanalytical method validation and meets the requirements for detecting illegally used antiviral drugs in yellow catfish. The demonstrated G/KCC-1 based PT-SPE UPLC-MS/MS method is a potential analytical method in food and drug administration.

The Economic and Technical Efficiency of Yellow Cat Fish (Pelteobagrus Fulvidraco) Production in China

China’s yellow catfish (Pelteobagrus fulvidraco) productions has undergone a rapid growth since the year 2000 and Its Productions increased high ranging from 50, 000 tones to 114, 000 tons in 2007, and to over 300, 000 tons in 2014 by far the largest producer in the world. Yellow catfish (Pelteobagrus fulvidraco) are freshwater species native to Chinese waters. The aim of the study is to provide a better understanding on the present trends in the economic and technical efficiency of Yellow catfish (Pelteobagrus fulvidraco) production in China and learn from the Chinese wider experiences as a guide to the developing countries as they strive to develop their aquaculture sectors. The method of the study employed secondary data information collected from the reputable sources such as Food and Agriculture Organization of the United Nations, Nanjing Agriculture University-electronic library, China fisheries year books and annual reports including other relevant websites browsed containing some valuable information about Chinese aquaculture status and the data gathered was analyzed. Freshwater aquaculture in China has made a concerted effort to uplift culture practices on selected, high-valued, indigenous fish species. Currently yellow catfish has well established seed production technology, feed production, and efficient culture technology systems. It’s economically preferred by many consumers both in the local markets as well as international markets particularly by the south-eastern Asian countries like Japan and Korea. Despite the economic importance of yellow catfish species in the aquaculture sector, there is still limited information on its economic and technical efficiency production. Thus, this review paper highlights the economic and technical efficiency of yellow catfish production performances and focus on identifying critical matters that can support and improve yellow catfish productions in China as well as in the developing countries.

Dietary Glutamine Inclusion Regulates Immune and Antioxidant System, as Well as Programmed Cell Death in Fish to Protect against Flavobacterium columnare Infection.

The susceptibility of animals to pathogenic infection is significantly affected by nutritional status. The present study took yellow catfish (Pelteobagrus fulvidraco) as a model to test the hypothesis that the protective roles of glutamine during bacterial infection are largely related to its regulation on the immune and antioxidant system, apoptosis and autophagy. Dietary glutamine supplementation significantly improved fish growth performance and feed utilization. After a challenge with Flavobacterium columnare, glutamine supplementation promoted il-8 and il-1β expression via NF-κB signaling in the head kidney and spleen, but inhibited the over-inflammation in the gut and gills. Additionally, dietary glutamine inclusion also enhanced the systematic antioxidant capacity. Histological analysis showed the protective role of glutamine in gill structures. Further study indicated that glutamine alleviated apoptosis during bacterial infection, along with the reduced protein levels of caspase-3 and the reduced expression of apoptosis-related genes. Moreover, glutamine also showed an inhibitory role in autophagy which was due to the increased activation of the mTOR signaling pathway. Thus, our study for the first time illustrated the regulatory roles of glutamine in the fish immune and antioxidant system, and reported its inhibitory effects on fish apoptosis and autophagy during bacterial infection.

Fish Diversity Monitored by Environmental DNA in the Yangtze River Mainstream

Surveys and assessments based on environmental DNA are not only efficient and time-saving, but also cause less harm to monitoring targets. Environmental DNA has become a common tool for the assessment and monitoring of aquatic organisms. In this study, we investigated fish resources in the Yangtze River mainstream using environmental DNA, and the variations in fish during two seasons (spring and autumn) were compared. The results showed that 13 species were identified in spring, and nine species of fish were identified in autumn. The fish with higher eDNA detection were Sinibotia superciliaris, Tachysurus fulvidraco, Cyprinus carpio, Ctenopharyngodon Idella, Monopterus albus, Acanthogobius hasta, Saurogobio dabryi, Oncorhynchus mykiss, Mugil cephalus, Odontamblyopus rubicundus. Seasonal variation between spring and autumn was not significant, and the environmental factors had different effects on fish assemblages during the two seasons. Our study used the eDNA technique to monitor the composition of fish in the spring and autumn in the Yangtze River mainstream, providing a new technology for the long-term management and protection of fishery resources in the region. Of course, problems such as pollution and insufficient databases are the current shortcomings of environmental DNA, which will be the focus of our future research and study.

Comparative Transcriptomic Analysis of Regenerated Skins Provides Insights into Cutaneous Air-Breathing Formation in Fish.

Simple SummaryCutaneous air-breathing is one of the air-breathing patterns in bimodal respiration fishes, while little is known about its underlying formation mechanisms. The skin regeneration of loach (Misgurnus anguillicaudatus, a cutaneous air-breathing fish) and yellow catfish (Pelteobagrus fulvidraco, a water-breathing fish) were first investigated through morphological and histological observations. Then, the original skins (OS: MOS, POS) and regenerated skins (RS: MRS, PRS) when their capillaries were the most abundant during healing, of the two fish species were collected for high-throughput RNA-seq. A total of 56,054 unigenes and 53,731 unigenes were assembled in loach and yellow catfish, respectively. A total of 640 (460 up- and 180 down-regulated) and 4446 (2340 up- and 2106 down-regulated) differentially expressed genes (DEGs) were respectively observed in RS/OS of loach and yellow catfish. Subsequently, the two DEG datasets were clustered in GO, KOG, and KEGG databases, and further analyzed by comparison and screening. Consequently, tens of genes and thirteen key pathways were targeted, indicating that these genes and pathways had strong ties to cutaneous skin air-breathing in loach. This study provides new insights into the formation mechanism of cutaneous air-breathing and also offers a substantial contribution to the gene expression profiles of skin regeneration in fish.Cutaneous air-breathing is one of the air-breathing patterns in bimodal respiration fishes, while little is known about its underlying formation mechanisms. Here, we first investigated the skin regeneration of loach (Misgurnus anguillicaudatus, a cutaneous air-breathing fish) and yellow catfish (Pelteobagrus fulvidraco, a water-breathing fish) through morphological and histological observations. Then, the original skins (OS: MOS, POS) and regenerated skins (RS: MRS, PRS) when their capillaries were the most abundant (the structural foundation of air-breathing in fish) during healing, of the two fish species were collected for high-throughput RNA-seq. A total of 56,054 unigenes and 53,731 unigenes were assembled in loach and yellow catfish, respectively. A total of 640 (460 up- and 180 down-regulated) and 4446 (2340 up- and 2106 down-regulated) differentially expressed genes (DEGs) were respectively observed in RS/OS of loach and yellow catfish. Subsequently, the two DEG datasets were clustered in GO, KOG and KEGG databases, and further analyzed by comparison and screening. Consequently, tens of genes and thirteen key pathways were targeted, indicating that these genes and pathways had strong ties to cutaneous skin air-breathing in loach. This study provides new insights into the formation mechanism of cutaneous air-breathing and also offers a substantial contribution to the gene expression profiles of skin regeneration in fish.

Effects of tricaine methanesulfonate (MS-222) on sedation and responses of yellow catfish (Pelteobagrus fulvidraco) subjected to simulated transportation stress

This study evaluated the anesthetic and sedative effects of tricaine methanesulfonate (MS-222) on yellow catfish (Pelteobagrus fulvidraco), and determined its effectiveness for the simulated transportation. In the anesthesia induction and recovery experiment, the adult fish (87.5 ± 13.9 g) were treated with five concentrations of MS-222 (0, 40, 60, 90 and 110 mg L−1), respectively. The results showed that the effective concentration of MS-222 for short-term anesthesia induction was between 90 and 110 mg L−1, according to the principle of anesthesia within 3 min and recovery within 10 min. In the simulated transportation experiment, the fish (86.7 ± 11.4 g) were stored in tanks containing 40 mg L−1 MS-222 solution for 12 h. The results revealed that the content of water ammonia nitrogen in the MS-222 group was significantly lower than that of control group . The fish in the anesthetized transportation group showed a significant decrease in serum cortisol levels (43.11 ± 3.74 ng mL−1) compared with the control group (50.12 ± 0.65 ng mL−1), whereas the levels of serum glucose in fish exposed to MS-222 significantly increased . The hsp70 mRNA expression in the liver of anesthetized yellow catfish was found to significantly upregulate after transportation . Thus, it is concluded that the effective concentrations of MS-222 for sedation and anesthesia in adult yellow catfish were from 90 to 110 mg L−1, and while 40 mg L−1 MS-222 has the potential to be used for the transportation of yellow catfish within 12 h.

Ammonia induces changes in carbamoyl phosphate synthetase I and its regulation of glutamine synthesis and urea cycle in yellow catfish Pelteobagrus fulvidraco

Fishes can adapt to certain levels of environmental ammonia in water, but the strategies utilized to defend against ammonia toxicity are not exactly the same. The carbamyl phosphate synthase I (CPS I) plays an important role in the regulation of glutamine synthesis and urea cycle, which are the most common strategies for ammonia detoxification. In this study, CPS I was cloned from the yellow catfish. The full-length cDNAs of the CPS I was 5 034 bp, with open reading frames of 4 461 bp. Primary amino acid sequence alignment of CPS I revealed conserved similarity between the functional domains of the yellow catfish CPS I protein with CPS I proteins of other animals. The mRNA expression of CPS I was significantly up-regulated in liver and kidney tissues after acute ammonia stress. The CPS I RNA interference (RNAi) down-regulated the mRNA expressions of CPS I and ornithine transcarbamylase (OTC), but up-regulated glutamine synthetase (GS) and glutamate dehydrogenase (GDH) expressions in primary culture of liver cell after acute ammonia stress. Similarly, the activity of enzymes related to urea cycle decreased significantly, while the activity of enzymes related to glutamine synthesis increased significantly. The results of RNAi in vitro suggested that when the urea cycle is disturbed, the glutamine synthesis will be activated to cope with ammonia toxicity.

Dietary Nano-ZnO Is Absorbed via Endocytosis and ZIP Pathways, Upregulates Lipogenesis, and Induces Lipotoxicity in the Intestine of Yellow Catfish.

Nano-sized zinc oxide (nano-ZnO) affects lipid deposition, but its absorption patterns and mechanisms affecting lipid metabolism are still unclear. This study was undertaken to investigate the molecular mechanism of nano-ZnO absorption and its effects on lipid metabolism in the intestinal tissues of a widely distributed freshwater teleost yellow catfish Pelteobagrus fulvidraco. We found that 100 mg/kg dietary nano-ZnO (H-Zn group) significantly increased intestinal Zn contents. The zip6 and zip10 mRNA expression levels were higher in the H-Zn group than those in the control (0 mg/kg nano-ZnO), and zip4 mRNA abundances were higher in the control than those in the L-Zn (50 mg/kg nano-ZnO) and H-Zn groups. Eps15, dynamin1, dynamin2, caveolin1, and caveolin2 mRNA expression levels tended to reduce with dietary nano-ZnO addition. Dietary nano-ZnO increased triglyceride (TG) content and the activities of the lipogenic enzymes glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), and isocitrate dehydrogenase (ICDH), upregulated the mRNA abundances of lipogenic genes 6pgd, fatty acid synthase (fas), and sterol regulatory element binding protein 1 (srebp1), and reduced the mRNA expression of farnesoid X receptor (fxr) and small heterodimer partner (shp). The SHP protein level in the H-Zn group was lower than that in the control and the L-Zn group markedly. Our in vitro study indicated that the intestinal epithelial cells (IECs) absorbed nano-ZnO via endocytosis, and nano-Zn-induced TG deposition and lipogenesis were partially attributable to the endocytosis of nano-ZnO in IECs. Mechanistically, nano-ZnO-induced TG deposition was closely related to the metal responsive transcription factor 1 (MTF-1)-SHP pathway. Thus, for the first time, we found that the lipogenesis effects of nano-ZnO probably depended on the key gene shp, which is potentially regulated by MTF1 and/or FXR. This novel signaling pathway of MTF-1 through SHP may be relevant to explain the toxic effects and lipotoxicity ascribed to dietary nano-ZnO addition.