Search Results (9)

This study investigates the role of the Opnod1, Opnod2, and Optbk1 genes in antiviral and antibacterial immunity of spotted knifejaw (Oplegnathus punctatus). The expression patterns of these genes were analyzed using qRT-PCR in different tissues and at different time points. The open reading frame (ORF) of the Opnod1 gene was 2757 bp in length and encoded 918 amino acids, the ORF of the Opnod2 gene was 2970 bp in length and encoded 990 amino acids, while the Optbk1 gene was 2172 bp in length and encoded 723 amino acids. The Opnod1 and Opnod2 proteins contained three conserved domains (CARD, NOD, and LRR), and Optbk1 contained an STKc domain. The Opnod1, Opnod2, and Optbk1 genes were mainly expressed in immune-related tissues of spotted knifejaw, with the highest relative expression of the Opnod1 in the skin, the Opnod2 in the gill, and the Optbk1 in the liver. The expression of these genes changed significantly in the immune tissues following infection with SKIV-SD and Vibrio harveyi. In kidney cells, the Opnod1, Opnod2, and Optbk1 expression was up-regulated after stimulation by poly I:C and LPS in vitro. The results suggest that the NOD1/2-TBK1 signal pathway may play an important role in the resistance of the spotted knifejaw to virus and bacteria, providing valuable insights for disease-resistant breeding. Full article

(1) Background: Laizhou Bay is an important aquaculture area in the north of China. Oplegnathus punctatus is one of the species with high economic benefits. In recent years, the water environment of Laizhou Bay has reached a mild eutrophication level, while microorganisms are an important group between the environment and species. In this study, we evaluated alterations in environmental elements, microbial populations, and antibiotic resistance genes (ARGs) along with their interconnections during Oplegnathus punctatus net culture. (2) Methods: A total of 142 samples from various water layers were gathered for metagenome assembly analysis. Mariculture increases the abundance of microorganisms in this culture area and makes the microbial community structure more complex. The change had more significant effects on sediment than on seawater. (3) Results: Certain populations of cyanobacteria and Candidatus Micrarchaecta in seawater, and Actinobacteria and Thaumarchaeota in sediments showed high abundance in the mariculture area. Antibiotic resistance genes in sediments were more sensitive to various environmental factors, especially oxygen solubility and salinity. (4) Conclusions: These findings highlight the complex and dynamic nature of microorganism–environment–ARG interactions, characterized by regional specificity and providing insights for a more rational use of marine resources. Full article

Understanding the feeding dynamics of aquatic animals is crucial for aquaculture optimization and ecosystem management. This paper proposes a novel framework for analyzing fish feeding behavior based on a fusion of spectrogram-extracted features and deep learning architecture. Raw audio waveforms are first transformed into Log Mel Spectrograms, and a fusion of features such as the Discrete Wavelet Transform, the Gabor filter, the Local Binary Pattern, and the Laplacian High Pass Filter, followed by a well-adapted deep model, is proposed to capture crucial spectral and spectral information that can help distinguish between the various forms of fish feeding behavior. The Involutional Neural Network (INN)-based deep learning model is used for classification, achieving an accuracy of up to 97% across various temporal segments. The proposed methodology is shown to be effective in accurately classifying the feeding intensities of Oplegnathus punctatus, enabling insights pertinent to aquaculture enhancement and ecosystem management. Future work may include additional feature extraction modalities and multi-modal data integration to further our understanding and contribute towards the sustainable management of marine resources. Full article

As a member of the forkhead box L gene family, foxl2 plays a significant role in gonadal development and the regulation of reproduction. During the evolution of deuterostome, whole genome duplication (WGD)-enriched lineage diversifications and regulation mechanisms occurs. However, only limited research exists on foxl2 duplication in teleost or other vertebrate species. In this study, two foxl2 paralogs, foxl2 and foxl2l, were identified in the transcriptome of spotted knifejaw (Oplegnathus punctatus), which had varying expressions in the gonads. The foxl2 was expressed higher in the ovary, while foxl2l was expressed higher in the testis. Phylogenetic reconstruction, synteny analysis, and the molecular evolution test confirmed that foxl2 and foxl2l likely originated from the first two WGD. The expression patterns test using qRT-PCR and ISH as well as motif scan analysis revealed evidence of potentially functional divergence between the foxl2 and foxl2l paralogs in spotted knifejaw. Our results indicate that foxl2 and foxl2l may originate from the first two WGD, be active in transcription, and have undergone functional divergence. These results shed new light on the evolutionary trajectories of foxl2 and foxl2l and highlights the need for further detailed functional analysis of these two duplicated paralogs. Full article

To determine the impact of replacing fish meal (FM) in the diet with various levels of soybean meal (SBM) on the spotted knifejaw Oplegnathus punctatus, a 56 day feeding trial was done. Seven diets were formulated with SBM to replace 0% (SBM0), 30% (SBM30), 40% (SBM40), 50% (SBM50), 60% (SBM60), and 70% (SBM70) of FM protein, and SBM50 + T was developed on the basis of SBM50 with the addition of 1.2% taurine. There were triplicate groups of 18 fish (initial weight: 14.62 ± 0.02 g). The weight gain (WG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER) values of the SBM0, SBM30, and SBM50 + T groups were found to be significantly higher than those of the SBM60 and SBM70 groups (p < 0.05). The daily energy gain (DEG), daily nitrogen gain (DNG), daily lipid gain (DLG), energy retention (ER), nitrogen retention (NR), and lipid retention (LR) values decreased significantly with increasing dietary SBM levels (p < 0.05). The highest retention of most amino acids (except lysine) was observed in the SBM30 group (p < 0.05). The lipid content of the whole body and dorsal muscle decreased significantly as dietary SBM levels increased (p < 0.05). Fish fed the SBM70 diet had the lowest serum triglyceride (TG) concentrations (p < 0.05). The effects of different treatments on total cholesterol (T-CHO) were not significant (p > 0.05). Fish fed the SBM0 and SBM30 diets had the highest amylase (AMS) and lipase (LPS) activities (p < 0.05). The lowest liver superoxide dismutase (SOD) and catalase (CAT) activities were observed in the SBM70 group. The malondialdehyde (MDA) concentration of the SBM50 to SBM70 groups were significantly higher than that of other groups (p < 0.05). The levels of interleukin 8 (il-8) mRNA were highest in fish fed the SBM0, SBM30, and SBM50 + T diets (p < 0.05), while the level of transforming growth factor β1 (tgf-β1) was the opposite (p < 0.05). According to the broken line regression of WG and FE, the highest level of FM substitution by SBM for Oplegnathus punctatus was 24.07–25.31%. Full article

The spotted knifejaw (Oplegnathus punctatus) is a marine economic fish with high ecological value, food value, and fishing value, and its growth has obvious sex dimorphism. The rapid identification of its sex is beneficial to the development of sex determination and breeding. In this study, the method of comparative genomics and PCR amplification was used to further establish a rapid detection method for the recombinant RhoGEF10 gene in O. punctatus, which can quickly, accurately, and efficiently identify the sex of the O. punctatus to be tested. The homologous comparison results of male and female individuals showed that the DNA fragment length of the RhoGEF10 gene on the X1 chromosome was 326 bp, and the DNA fragment length on the Y chromosome was 879 bp. Therefore, it can be concluded that there is an insert fragment of 553 bp on the Y chromosome. PCR amplification results showed that the two DNA fragments of 879 bp and 326 bp were amplified in the Y chromosome and X1 chromosome of the male O. punctatus (X1X2Y), respectively, and the 879 bp fragment was a unique marker fragment of the recombinant RhoGEF10 gene; The female O. punctatus (X1X1X2X2) only a single DNA fragment of 326 bp was amplified. At the same time, the inserted fragment of the male individual resulted in partial inactivation of the RhoGEF10 protein, which in turn resulted in a slowing of peripheral nerve conduction velocity and thinning of the myelin sheath in male O. punctatus. The method shortens the time for accurate identification of the O. punctatus RhoGEF10 gene recombination and improves the detection efficiency. It is of great significance and application value in the research of nerve conduction and myelin development, male and female sex identification, the preparation of high male seedlings, and family selection based on the RhoGEF10 gene in the O. punctatus. Full article

Aquaculture plays a key role in food production globally and provides a valuable source of protein and nutrition, addressing a worldwide growing demand. Oplegnathus punctatus (spotted knifejaw) is an economically important fish species with a high market value and demand. Previous studies on O. punctatus focused mainly on gonadal development, chromosomal microstructure, selective breeding, characterization of immune genes, and viral diseases. There is no published scientific research regarding vibriosis in this fish species. In this study, two potential pathogenic bacteria, Vibrio harveyi and Enterococcus gallinarum, were isolated from moribund cultured O. punctatus. The sequence of the universal 16S rDNA gene was used to identify potential pathogenic bacteria isolated from the moribund O. punctatus, and morphological assessments and API20E tests of the bacterial isolates were conducted to verify the identity and biochemical characteristics of the isolates. Injection of E. gallinarum did not lead to mortality in O. punctatus during the 21 days of observation. In contrast, fish died overnight when challenged with V. harveyi at 1.25 × 10⁵ CFU/g body weight, suggesting that the cause of death of the cultured O. punctatus was V. harveyi infection. Antimicrobial sensitivity analyses revealed that the V. harveyi strain NTOU is sensitive to flumequine, doxycycline, oxolinic acid, and amoxycillin. Importantly, we demonstrated for the first time that intraperitoneal administration of an inactivated V. harveyi whole-cell vaccine resulted in a high level of protection against V. harveyi infection in O. punctatus. Full article

Oplegnathus fasciatus and O. punctatus (Teleostei: Centrarchiformes: Oplegnathidae), are commercially important rocky reef fishes, endemic to East Asia. Both species present an X₁X₂Y sex chromosome system. Here, we investigated the evolutionary forces behind the origin and differentiation of these sex chromosomes, with the aim to elucidate whether they had a single or convergent origin. To achieve this, conventional and molecular cytogenetic protocols, involving the mapping of repetitive DNA markers, comparative genomic hybridization (CGH), and whole chromosome painting (WCP) were applied. Both species presented similar 2n, karyotype structure and hybridization patterns of repetitive DNA classes. 5S rDNA loci, besides being placed on the autosomal pair 22, resided in the terminal region of the long arms of both X₁ chromosomes in females, and on the X₁ and Y chromosomes in males. Furthermore, WCP experiments with a probe derived from the Y chromosome of O. fasciatus (OFAS-Y) entirely painted the X₁ and X₂ chromosomes in females and the X₁, X₂, and Y chromosomes in males of both species. CGH failed to reveal any sign of sequence differentiation on the Y chromosome in both species, thereby suggesting the shared early stage of neo-Y chromosome differentiation. Altogether, the present findings confirmed the origin of the X₁X₂Y sex chromosomes via Y-autosome centric fusion and strongly suggested their common origin. Full article

Ciguatoxins (CTXs) contaminate fish worldwide and cause the foodborne illness ciguatera. In the Pacific, these toxins are produced by the dinoflagellate Gambierdiscus toxicus, which accumulates in fish through the food chain and undergoes oxidative modification, giving rise to numerous analogs. In this study, we examined the oxidation of CTXs in vitro with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis using reference toxins, and found that CTX4A, CTX4B, and CTX3C, which are produced by the alga, are oxidized to the analogs found in fish, namely CTX1B, 52-epi-54-deoxyCTX1B, 54-deoxyCTX1B, 2-hydroxyCTX3C, and 2,3-dihydroxyCTX3C. This oxidation was catalyzed by human CYP3A4, fish liver S9 fractions, and microsomal fractions prepared from representative ciguateric fishes (Lutjanus bohar, L. monostigumus, and Oplegnathus punctatus). In addition, fish liver S9 fractions prepared from non-ciguateric fishes (L. gibbus and L. fulviflamma) in Okinawa also converted CTX4A and CTX4B to CTX1B, 54-deoxyCTX1B, and 52-epi-54-deoxyCTX1B in vitro. This is the first study to demonstrate the enzymatic oxidation of these toxins, and provides insight into the mechanism underlying the development of species-specific toxin profiles and the fate of these toxins in humans and fish. Full article