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The topmouth culter (Culter alburnus) is at the top of the food chain and plays an important role in the maintenance of freshwater ecosystem stability. It is also a commercially important aquaculture fish species in China. To establish conservation strategies and breeding programs, a total of 16 polymorphic microsatellite loci were isolated from transcriptome-derived sequences of C. alburnus. Characterization of these loci was assessed against 1 wild and 3 cultured populations in Huzhou, China. The number of alleles per locus ranged from 3 to 10 with an average of 5.25. A bottleneck effect was observed in all 4 populations; The ChangXing population showed moderate genetic differentiation when compared with other populations (FST values, 0.0695–0.0788). The microsatellite loci would be useful for further studies on population genetic diversity, genetic structure, and assessments of the artificial propagation release effect of C. alburnus.

The igfbp family proteins are key regulators of the biological activities of igfs, which play a pivotal role in controlling growth. Growth is highly variable between different fish species and even between growth stages and sexes within the same fish species. For determining the igfbps significantly associated to growth, we identified igfbp genes from the whole-wide genomes of mandarin fish Siniperca chuatsi and big-eye mandarin fish Siniperca kneri, and detected their expression profiles under different growth conditions. The results revealed that: 1) both mandarin fish and big-eye mandarin fish have 10 igfbp family members (igfbp-1a/b, igfbp-2a/b, igfbp-3, igfbp−4, igfbp-5a/b, and igfbp-6a/b), which are highly conserved among igfbp family members; 2) in early development, the expression of igf1 mRNA showed an increasing trend, igfbp-1a/b expression increased significantly with development and the expression trend was strongly similar to that of igf1; 3) variation of body sizes in adult revealed a strong correlation between the serum Gh content and igf1 mRNA expression level in the liver, and the expression levels of hepatic igfbp-2a/b, -4 showed a positive correlation; 4) serum Gh levels and the relative expression of hepatic igf1 mRNA were significantly higher in females than in males, the fold change in igfbp-1a in muscle, -2a, -5a in liver mRNA expression was strongly similar to that of igf1; 5) variation of the interspecific growth showed that the expression of serum Gh and hepatic igf1 mRNA in mandarin fish was significantly higher than that in big-eye mandarin fish. The expression of igfbps mRNA in mandarin fish was significantly higher than that in big-eye mandarin fish, except for igfbp-2a/2b in muscle and igfbp-6a in liver. Taken together, our results suggest that the different effects on growth of mandarin fish are regulated by the actions of different igfbps, where igfbp-1a/b, -2a/b, -4 and -5a may be a candidate for growth rate difference studies. The inherently low expression of Gh, igf1, and igfbps might have contributed to the slow growth of big-eye mandarin fish.

Diel variation of dissolved oxygen content in aquaculture is common. Generally, the dissolved oxygen content in the pond is the highest in the afternoon and the lowest in the early morning. Siniperca chuatsi usually feeds in the early morning because of its unique feeding habits, therefore the low dissolved oxygen level may affect its metabolism. In this study, S. chuatsi was subjected to different oxygen conditions, a control group (> 5 mg/L) and an experimental group (dissolved oxygen changed with sunlight) for 24 h to determine glucose metabolism systemically. The following results were obtained: (1) Dissolved oxygen level in the experimental group that underwent periodic variation was the lowest at 07:00, with an average dissolved oxygen level of 0.93 mg/L; and the dissolved oxygen was the highest at 17:00, with an average dissolved oxygen level of 10.58 mg/L. (2) At T3 and T4, the plasma content of experimental group significantly decreased and lactic acid content increased significantly; liver glycogen and ATP content decreased, whereas lactic acid content increased significantly. (3) At T3 and T4, the activities of the key enzymes involved in glucose metabolism in liver varied; the activity of aerobic metabolism enzyme citrate synthase (CS) significantly decreased while that of anaerobic metabolism enzyme lactate dehydrogenase (LDH) increased significantly; the activity of glycolysis enzyme hexokinase (HK), phosphate fructose kinase (PFK), pyruvate kinase (PK) increased significantly and the activity of glycogenolytic enzyme glycogen phosphorylase (GP) exhibited no significant difference. (4) At T3 and T4, the expression of hk, pfk, pk, ldh-a, gp genes in the experimental group increased significantly, the expression of cs significantly decreased, and the expression of glucose transporter 2 (glut2) was not significant difference. Thus, when diel variation periodically changed dissolved oxygen level in the pond, lower dissolved oxygen level lead to change in glucose metabolism, from aerobic metabolism to anaerobic metabolism, and the energy utilization mode of S. chuatsi had changrd.

Summary: We identified that the genes heat shock transcription factor 5 (hsf5) and ring finger protein 43 (rnf43) happened fusion in Nile tilapia (Oreochromis niloticus), called hsf5-rnf43, and provided the characteristic and functional analysis of hsf5-rnf43 gene in fish for the first time. Analysis of spatiotemporal expression showed that hsf5-rnf43 was specifically expressed in the testis and located in primary spermatocytes of adult Nile tilapia and gradually increased during testis development from 5 to 180 days after hatching. We also found DNA methylation regulated sex-biased expression of hsf5-rnf43 in the early development of Nile tilapia, and was affected by high temperature during the thermosensitive period of Nile tilapia sex differentiation. Therefore, we first reported that the fusion gene hsf5-rnf43 was sex-biased expressed in the testis regulated by DNA methylation and affected by high temperature, which may be involved in the maintenance of testis function and sex differentiation of Nile tilapia.

A 56-day experiment was conducted to investigate the effects of ambient salinity and alkalinity on fatty acids, free amino acids and related anabolic metabolisms of Nile tilapia. The fatty acid and free amino acid contents in the muscle of tilapia cultured in saline water (SW), alkaline water (AW), saline–alkaline water (SAW) and fresh water (FW) conditions were analyzed and compared. The mRNA levels and enzymatic activities of fatty acyl desaturase (FADS2), elongation of very long-chain fatty acids (ELOVL5), Δ1-pyrroline-5-carboxylate synthase (P5CS), ornithine-δ-aminotransferase (δ-OAT), and proline dehydrogenase (PDH) were also determined. The contents of saturated and monounsaturated fatty acids were significantly higher in the AW and SAW groups than those in the SW group, and those of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were the highest in the SAW group. The contents of flavor amino acids in the SAW and AW groups were significantly higher than that in the SW group, and that of proline in the SW, AW, and SAW groups was 3.58-, 4.11-, and 4.15-times higher than that in the FW group. The mRNA levels and enzyme activities of FADS 2, ELOVL5, PDH and P5CS were found to differ among the different groups. The results suggested that ambient salinity and alkalinity could effectively improve flesh quality of tilapia by regulating lipid and proline metabolism pathways.

Topmouth culter (Culter alburnus) is an economically important freshwater fish with high nutritional value. However, its potential genetic advantages have not been fully exploited. Therefore, we aimed to determine the genome sequence of C. alburnus and examine quantitative trait loci (QTLs) related to major economic traits. The results showed that 24 pseudochromosomes were anchored by 914.74 Mb of the C. alburnus genome sequence. De novo sequencing identified 31,279 protein-coding genes with an average length of 8507 bp and average coding sequ ence of 1115 bp. In addition, a high-density genetic linkage map consisting of 24 linkage groups was constructed based on 353,532 high-quality single nucleotide polymorphisms and 4,710 bin markers. A total of 28 QTLs corresponding to 11 genes, 26 QTLs corresponding to 11 genes, and 12 QTLs corresponding to 5 genes were identified for sex, intermuscular spine number and body weight traits, respectively. In this study, we assembled an accurate and nearly complete genome of C. alburnus by combining Illumina, PacBio, and high-throughput Chromosome conformation capture (Hi-C) technologies. In addition, we identified QTLs that explained variances in intermuscular spine number, body weight, and sex differences in C. alburnus. These genetic markers or candidate genes associated with growth traits provide a basis for marker-assisted selection in C. alburnus.

MicroRNAs (miRNAs) are short noncoding sequences that can regulate the expression of target genes. Erythrocytes, also called red blood cells (RBCs), are the largest proportion of cells in blood. Erythrocytes deliver oxygen in the body of vertebrates and contribute to the body's immune function. Illumina sequencing technology was used to analyze pooled RNA samples isolated from erythrocytes, in order to characterize their gene expression profile and increase the range of miRNAs identified in Nile tilapia erythrocytes. This study identified conserved (n = 309) and novel (n = 194) miRNAs. Quantitative reverse-transcription polymerase chain reaction and next-generation sequencing results indicated that miR-451 was the most abundant in RBCs, followed by let-7a-1, miR-2188 and miR-144. Moreover, the tissue expression mode of these highly expressed miRNAs was characterized. Results show that miR-451, miR-2188, and miR-144 were all highly expressed in RBCs but were low abundance in other tissues. miR-1 and miR-10b were also abundantly expressed in muscle, while miR-122 was abundantly expressed in the liver. let-7a-1, miR-10b, and miR-1 were significantly higher in the testis than in the ovary. The tissue distribution of miRNAs implies that these noncoding sequences have a potential role in regulating tissue differentiation or maintaining tissue characteristics. The results of a dual-luciferase reporter assay indicated that miR-144 and miR-10b inhibited the expression of the meningioma expressed antigen 5 gene in vitro. This study contributes to the Nile tilapia miRNA database and reveals the profile of erythrocyte miRNA expression.

Abstract Bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix), collectively called bigheaded carps, are cyprinids native mainly to China and have been introduced to over 70 countries. Paleontological and molecular phylogenetic analyses demonstrate bighead and silver carps originated from the Yangtze‐Huanghe River basins and modern populations may have derived from the secondary contact of geographically isolated fish during the last glacial events. Significant genetic differences are found among populations of native rivers (Yangtze, Pearl, and Amur) as well as introduced/invasive environments (Mississippi R., USA and Danube R., Hungary), suggesting genetic backgrounds and ecological selection may play a role in population differentiation. Population divergence of bighead carp or silver carp has occurred within their native rivers, whereas, within the Mississippi River Basin (MRB)—an introduced region, such genetic differentiation is likely taking place at least in silver carp. Interspecific hybridization between silver and bighead carps is rare within their native regions; however, extensive hybridization is observed in the MRB, which could be contributed by a shift to a more homogenous environment that lacks reproductive isolation barriers for the restriction of gene flow between species. The wild populations of native bighead and silver carps have experienced dramatic declines; in contrast, the introduced bigheaded carps overpopulate the MRB and are considered two invasive species, which strongly suggests fishing capacity (overfishing and underfishing) be a decisive factor for fishery resource exploitation and management. This review provides not only a global perspective of evolutionary history and population divergence of bigheaded carps but also a forum that calls for international research collaborations to deal with critical issues related to native population conservation and invasive species control.

The big-eye mandarin fish (Siniperca knerii) is an endemic species of southern China. It belongs to the family Sinipercidae, which is closely related to the well-known North American sunfish family Centrarchidae. Determining the genome sequence of S. knerii would provide a foundation for better examining its genetic diversity and population history. A novel sequenced genome of the Sinipercidae also would help in comparative study of the Centrarchidae using Siniperca as a reference. Here, we determined the genome sequence of S. knerii using 10x Genomics technology and next-generation sequencing. Paired-end sequencing on a half lane of HiSeq X platform generated 56 Gbp of raw data. Read assembly using Supernova assembler resulted in two haplotype genomes with 732.1 Mb in size and an average GC content of 40.4%, which is consistent with genome size previously reported or estimated using k-mer counting. A total of 7,989 scaffolds with an N50 score of 12.64 Mb were obtained. The longest scaffold was 30.54 Mb. Evaluation of the genome completeness using BUSCO confirmed that 96.5% genes of the Actinopterygii Benchmarking Universal Single-Copy Orthologs were found in the assembled genome of S. knerii. Gene prediction using Maker annotation kit resulted in 28,440 genes, of which 25,899 genes had at least one hit comparing to the NCBI Nr database, KEGG or InterProScan5. Pairwise sequentially Markovian coalescent (PSMC) analysis of the genome showed that there was a bottleneck event of the population of S. knerii between 70 ka – 20 ka, which was concordant with the Tali glacier period, suggesting a population decline of S. knerii probably due to climate conditions.

Abstract Background Due to the continuous demand for fish coupled with decline in capture fisheries, there is the need to increase aquaculture production to meet the demand. Aquaculture is faced with high cost of feeding since fish oil and fish meal are expensive. In view of this, there are calls to explore alternatives that are cheap and reliable. Objectives This study on Oreochromis niloticus was conducted to evaluate the effects of replacing fish oil (FO) with palm oil (PO) at 0%, 25%, 50%, 75%, and 100% on muscle fatty acid and proximate composition as well as growth-related enzyme activities and mRNA expression. Methods Oreochromis niloticus were fed five experimental diets (33% crude protein and 10% crude lipid) for 8 weeks. Feed had variation in fish oil and palm oil contents. After the 8 weeks feeding trial, five fish were sampled from each tank (15 from each treatment) and euthanized using an excess dose of tricaine methane sulfonate (MS-222 at 200 mg/L). Fatty acid and enzyme activities were analyzed using standard protocols. Also, RT-qPCR was used to quantify the expression levels of selected growth-related genes. Results Fish fed 25% PO recorded the least muscle protein content and was significantly lower than the group fed 100% PO. Paired box protein 7 (Pax-7) enzyme activity was significantly higher in the group fed 50% PO compared to the groups fed 25% PO and 100% PO, while caplain-3 (Capn-3) was significantly lower in the group fed 0% PO compared to all other groups. There was a significant difference among treatments with respect to mRNA expression of Pax-7 and Capn-3. Group fed 25% PO had significantly lower mRNA expression of Pax-7, while the group fed 75% PO recorded significantly higher mRNA expression of Capn-3 compared to groups fed 0% PO, 25% PO, and 100% PO. Pearson’s correlation analysis revealed that Igf-I and Igf-II mRNA expression have significant correlation with n-3 polyunsaturated fatty acids content in muscle. Conclusion The results suggest muscle protein content could be modified if FO is replaced with PO. Also, mRNA expression of Pax-7 and Capn-3 is affected by replacing FO with PO.

The erythrocytes or red blood cells (RBCs) and leucocytes or white blood cells (WBCs) are the most abundant cell types in the circulatory system of vertebrates. The RBCs are responsible for gas exchange while WBCs are solely involved with immunity. In this study, we present evidence that fish RBCs despite their respiratory role they also express immune-related genes and responses in the teleost fish, Nile tilapia (Oreochromis niloticus). Fluorescent staining identified the presence of numerous mitochondria and lysosomes in tilapia RBCs. RNA sequencing of tilapia RBCs and WBCs led to the assembly and annotation of 20.876 transcripts of which 1017 and 3628 transcripts were specific to RBCs and WBCs, respectively. Pairwise sequence comparisons identified 3251 transcripts that were significantly differential expressed of which 707 (21.75%) were up-regulated and 2544 (78.25%) down-regulated in RBCs when compared to WBCs. 809 transcripts were assigned to 16 immune system pathways, 21 and 163 transcripts were specifically expressed in tilapia RBCs and WBCs respectively, and 23 and 233 transcripts were highly expressed in RBCs and WBCs respectively. Expression of 7 immune genes (interferon regulatory factors (irf) 1–5 and 9 and tlr3) in both WBCs and RBCs was validated by RT-PCR analysis. Quantitative real-time PCR revealed that all genes were up-regulated in poly(I:C)-challenged WBCs and irf (1, 3, 4, and 9) and tlr3 were also significantly up-regulated in poly(I:C)-challenged RBCs. Therefore, fish RBCs expressed immunity genes and responses and they may play a complementary role in vertebrate immunity.

This study was conducted to evaluate effects of dietary palm oil levels on growth performance, feed utilization, body composition and serum metabolites of Oreochromis niloticus. Five isonitrogenous diets, 32% crude protein with increasing palm oil levels of 0 (Control, CTRL), 2%, 4%, 6% and 8% were used as the major lipid source for the trial. The results showed that greatest weight gain, specific growth rate, and protein efficiency ratio occurred at 6% dietary palm oil level. Dietary palm oil levels significantly (P

Hall-effect in semiconductors has wide applications for magnetic field sensing. Yet, a standard Hall sensor retains two problems: its linearity is affected by the non-uniformity of the current distribution; the sensitivity is bias-dependent, with linearity decreasing with increasing bias current. In order to improve the performance, we here propose a novel structure which realizes bias-free, photo-induced Hall sensors. The system consists of a semi-transparent metal Pt and a semiconductor Si or GaAs to form a Schottky contact. We systematically compared the photo-induced Schottky behaviors and Hall effects without net current flowing, depending on various magnetic fields, light intensities and wavelengths of Pt/GaAs and Pt/Si junctions. The electrical characteristics of the Schottky photo-diodes were fitted to obtain the barrier height as a function of light intensity. We show that the open-circuit Hall voltage of Pt/GaAs junction is orders of magnitude lower than that of Pt/Si, and the barrier height of GaAs is smaller. It should be attributed to the surface states in GaAs which block the carrier drifting. This work not only realizes the physical investigations of photo-induced Hall effects in Pt/GaAs and Pt/Si Schottky junctions, but also opens a new pathway for bias-free magnetic sensing with high linearity and sensitivity comparing to commercial Hall-sensors.

This study was conducted to investigate the effects of replacing dietary fish oil (FO) with palm oil (PO) in juvenile Nile tilapia, Oreochromis niloticus (9.34± 0.02g initial weight) with emphasis on growth performance, digestive enzyme activities as well as serum biochemical parameters. Also, lysozyme activity (LYZ), respiratory burst (RB), superoxide dismutase (SOD), catalase (CAT) and resistance to Streptococcus iniae were investigated. Fish were stocked in 15 rectangular fiber glass tanks (150× 60× 40 cm) at 40 fish per tank with water maintained at 210 litres. Fish were fed five isonitrogenous (33% crude protein) and isolipidic (10% lipid) diets with PO included at 0% (0% PO), 25% (25% PO), 50% (50%PO), 75% (75% PO) and 100% (100% PO) for 8 weeks. The findings demonstrated that growth, and feed utilization was not compromised when PO was used in place of FO either partially or totally. Except for protease activity which was not significantly altered, lipase and amylase activities were significantly altered when FO was replaced with PO. There were no significant differences among treatments for CAT, SOD and LYZ. Serum malondialdehyde (MDA) in fish fed 100% PO was significantly lower than all other groups whiles total antioxidant capacity (TAC) of fish fed 0% PO was significantly higher than all other groups. Fish fed 0% PO, 25% PO and 50% PO had glutathione reductase (GR) significantly higher than fish fed 75% PO and 100% PO. RB in fish fed 0% PO were significantly lower than fish fed 75% PO and 100% PO. Also, fish fed 0% PO had significantly lower total protein (TP) compared with groups fed 50% PO and 75% PO. Fish fed diets with PO had similar resistance ability to Streptococcus iniae as those fed diets with FO. However, the liver function was likely to be compromised due to the increase in aspartate amino transferase (AST) and alkaline phosphatas (ALP) along increasing PO inclusion levels. AST, total protein, triacylglycerol (TAG) and low-density lipoprotein cholesterol (LDL-C) were significantly higher (p

Hepcidin is a liver-derived peptide hormone that is related to iron balance and immunity in humans. However, its function in Siniperca chuatsi has not been well elucidated. In this study, we analyzed the expression and function of the S. chuatsi hepcidin (Sc-hep) gene. Sc-hep was specifically expressed in the liver and appeared to be one of the most highly expressed genes in the liver. After spleen and kidney necrosis virus (ISKNV) infection and lipopolysaccharide (LPS) and polyinosinic—polycytidylic acid (Poly I:C) stimulation, the expression of Sc-hep in the liver increased by approximately 110, 6500, and 225 times, respectively. After ferrous sulfate (FS) injection, the expression of Sc-hep in the liver increased approximately 520-fold. We found that miR-19c-5p could inhibit Sc-hep expression. Five CpG dinucleotides distributed in the promoter region showed no differential methylation between the liver and the stomach, both presenting high methylation rates. After FS or LPS injection, the expression of three iron balance-related genes (FPN1, TFR1, and FTN) and five immune-related cytokine genes (IL-1β, IL8, TNF-α, TLR22, and SOCS3) significantly changed. These results indicate that Sc-hep participates in the regulation of iron balance and plays an important role in the immune system. Sc-hep increased approximately 52-fold when mandarin fish were domesticated with artificial diets. Sc-hep might be used as a real-time biomarker of mandarin fish liver because its expression markedly varies under different physiological conditions.

The peritoneum is mainly composed of mesothelial cells, fiber cells, and fibers, with many free cells that come from tissue capillaries. Siniperca chuatsi is a valuable fish commodity and important freshwater aquaculture species in China. With the increase in the scale of its breeding, bacterial and viral disease of the S. chuatsi has become increasingly rampant in recent years. This study analyzed the peritoneal gene expression profile using transcriptome technology for the first time. The results showed that 95,711 unigenes were expressed in the peritoneum with an average length of 920.72 bp. In addition to the housekeeping genes, the genes of extracellular matrix protein 1a (ecm1), Angiopoietin-related protein 4-like (angptl4) and cysteine-rich protein 1 (crip1) were highly expressed genes in the peritoneum, and they are key factors in peritoneal development and the maintenance of morphology. Meanwhile, many immune genes were also expressed in the peritoneum, including beta-2-microglobulin (b2m), MHC II invariant chain (cd74), prostate stem cell antigen-like protein (psca), claudin (cldn), heat shock protein 90 (hsp90), complement component 4 (c4), radical S-adenosyl methionine domain-containing protein 2 (rsad2), and cathepsin S (ctss). The RT-PCR results showed that different genes exhibited different expression profiles. The transcriptome data indicated that b2m, cldn, hsp90, c4, and rsad2 were highly expressed in the peritoneum. b2m, cd74, psca, c4, and ctss were highly expressed after embryonic hatching, whereas cldn, hsp90, and rsad2 were expressed at early embryonic stages. Quantitative PCR demonstrated that b2m, cd74, cldn, hsp90, c4, and ctss genes were highly expressed after immunostimulation. This study provides significant data for studying the morphological and functional diversity of fish peritoneum and lays a foundation for research on mandarin fish immunity. [ABSTRACT FROM AUTHOR]

Multifunctional buried interface modification is key to boost the performance of perovskite solar cells (PSCs). Herein, a multifunctional passivator, N-(2-hydroxyethyl) ethylene diamine triacetic acid trisodium salt (HEDTA-3Na), is employed to modify an SnO2 electron transport layer (ETL) for fabricating efficient and stable PSCs. It is found that the addition of HEDTA-3Na not only reduces defect state density by passivating uncoordinated Sn4+ and Pb2+ defects in an ETL/perovskite interface, but also forms appropriate energy band alignment, facilitating electron extraction, and improves the quality of the perovskite film with enlarged grain sizes. In addition, the Na+ ions can diffuse into the perovskite layer to passivate iodine vacancy defects and inhibit ion migration. As a result, the PSC with HEDTA-3Na modification achieves a champion PCE of 23.11% with enhanced VOC and FF compared to the control device (20.82%). Moreover, the unencapsulated HEDTA-3Na-modified PSC retains 90% of its initial efficiency after 1600 hours at 25 °C and 20–25% relative humidity under ambient conditions. This work offers a simple and effective approach to synergistically improve the performance of PSCs with a single multifunctional molecule. [ABSTRACT FROM AUTHOR]