Search Results (28)

Anthropogenic acidification is a long-term challenge to marine ecosystems. Though coastal acidification is intensifying, the large yellow croaker (Larimichthys crocea) exhibits good adaptability to pH fluctuations, the underlying mechanisms of which remain poorly understood. This study investigated the morphology, antioxidant enzyme activity, and gene expression of L. crocea under varying acidification conditions (pH 8.1 (H group), 7.8 (M group), and 7.4 (L group)). Water pH fluctuations were also monitored to explore the physiological responses and potential adaptive molecular mechanisms of L. crocea under various acidified environments. The results indicated that the water pH decreased in the H group, significantly increased in the L group (p < 0.05), and remained stable in the M group during the experiment. The lowest MDA content and the highest antioxidant enzyme activities (CAT, SOD, GSH-Px) were observed in L. crocea at pH 7.8, suggesting pH 7.8 was optimal for L. crocea. Transcriptomic analysis revealed distinct gene expression patterns between the gills and kidneys under acidification stress. Differentially expressed genes (DEGs) in the gills were primarily observed between the M and L groups (62.3%), whereas in the kidneys, the majority of DEGs were observed between the M and H groups (43.2%). These findings suggested that the gills play a critical role in adapting to low pH in L. crocea, while the kidneys were more responsive to high pH. Enrichment analysis identified critical pathways, including vasopressin-regulated water reabsorption, mineral reabsorption, and aldosterone-regulated sodium reabsorption, which are associated with water and ion metabolism. These pathways play a pivotal role in the acid–base homeostasis and metabolism of L. crocea. These results provide insights into the adaptive mechanisms of L. crocea to acidified environments, with implications for aquaculture management and future ocean acidification adaptation. Full article

The large yellow croaker, or Larimichthys crocea, is highly prized for its golden color and nutritional content. The purpose of this study was to investigate the differences in body composition, mucus biochemical indices and body color in five strains of large yellow croakers (body weight: 347.01 ± 5.86 g). To conduct genetic diversity analyses of the populations, a total of 50 tailfin samples were randomly chosen from the following populations of large yellow croakers: wild (LYC1), Dai-qu population (LYC2), Yongdai 1 (LYC3), Min-yuedong population (LYC4), and Fufa 1 (LYC5). The findings demonstrated that the LYC3 group’s pigment contents, crude protein, crude lipid, and chromatic values were comparable to those of the LYC1 group (p > 0.05). There was no significant difference between the LYC1 and LYC5 groups’ mucus superoxide dismutase (SOD) and catalase (CAT) activities (p > 0.05). The alkaline phosphatases (ALP), acid phosphatases (ACP), and lysozyme (LYS) activities of the mucus in the LYC1 group were not significantly different from the LYC3 group (p > 0.05). The back skin mRNA expressions of tyrosinase (tyr), tyrosinase-related protein 1 (tyrp1), dopachrome tautomerase (dct), microphtalmia-associated transcription factor (mitf), and melanocortin 1 receptor (mc1r) were significantly up-regulated in the LYC2 and LYC4 groups compared to the LYC1, LYC3, and LYC5 groups (p < 0.05). Forkhead box d3 (foxd3), paired box 3 (pax3), purine nucleoside phosphorylase 4a (pnp4a), aristaless-like homeobox 4a (alx4a), cAMP dependent protein kinase (pka), anaplastic lymphoma kinase (alk), leukocyte receptor tyrosine kinase (ltk), and colony stimulating factor (fms) were among the mRNA expressions of the abdominal skin in the LYC1, LYC3, and LYC5 groups significantly higher than those in the LYC2 and LYC4 groups (p < 0.05). In conclusion, the LYC3 group’s crude protein, crude lipid, carotenoid, and lutein contents were most similar to those of the large yellow croaker found in the wild. Furthermore, the molecular mechanism underlying the variations in body color among the various strains of large yellow croakers was supplied for additional research. Full article

E2F transcription factors regulate cell cycle progression by influencing the expression of proteins required for the G₁-S phase transition and DNA synthesis with its heterodimeric partners (DP1 or DP2). The dimerization domain is the E2Fs and DP1 protein interaction interface and is believed to function in protein dimerization. In this study, eight E2F transcription factors (PcE2F1–8) of large yellow croaker Pseudosciaena crocea and one dimerization partner (PcDP1) are identified in the genome of large yellow croakers. The prediction of E2Fs conserved domains revealed that PcE2F1–6 has one DNA-binding domain (DBD) and one dimerization-binding domain (DD), while PcE2F7–8 only possess two duplicate DBDs but not DD, indicating that E2F7–8 cannot form the E2F/DP1 heterodimer. To explore whether PcDP1 is a partner of PcE2F1–6, the ORF of PcE2F1–6 was cloned. Subsequently, its sequence characteristics, the expression pattern in healthy fish, and subcellular co-localization were analyzed, and an interaction between PcDP1 and PcE2F1–6 were detected directly by yeast two-hybrid and BiFC. The PcE2F1, PcE2F2, PcE2F3, PcE2F4, PcE2F5, and PcE2F6 genes encode a protein of 454, 448, 444, 392, 362, and 396 amino acids, respectively, with accession numbers QFZ93593.1, QFZ93594.1, QFZ93595.1, QFZ93596.1, QFZ93597.1, and QFZ93598.1, respectively. Sequence characteristics analysis found that PcE2F1–5 but not PcE2F6 proteins share the pocket protein-binding domain sequestering in dimerization domains and transactivation domains. The PcE2F1,2,4 proteins possess one nuclear localization signal (NLS), and PcE2F3 protein possess two NLSs, but there is no NLS in PcE2F5 and 6 protein. Moreover, PcE2F4 also contains one NES. However, PcE2F1–6 proteins were all located in nucleus by using Euk-mPloc 2.0 programs and were confirmed by performing the Cherry and EGFP reporter assay. Regarding co-expression of DP1, only E2F4 can transfer DP1’s subcellular location from cytoplasm to the nucleus. RT-qPCR analysis indicated that PcE2F1–6 are constitutively and tissue specifically expressed in all of the tissues tested of a healthy large yellow croaker. The PcE2F1–6, except for PcE2F3, mRNA levels were all detected higher in the liver. PcE2F1–4 were also highly specifically expressed in the kidney, PcE2F4,6 in the brain, and PcE2F5 in the spleen of a healthy large yellow croaker, respectively. Using a yeast two-hybrid system, PcE2F4 interacting with PcDP1 was identified. The interaction between PcE2F4 and PcDP1 was further confirmed by a bimolecular fluorescence complementation (BiFC) assay. Collectively, these results indicate that an interaction between PcE2F4 and PcDP1 was detected, which may form heterodimer E2F4/DP1 to regulate cell cycles and immune-related pathways in large yellow croakers. Full article

This study aims to clarify the influence of water flow on the behavior of the large yellow croaker (Larimichthys crocea). Although L. crocea is a key species in marine cage aquaculture, and the industry is increasingly adopting large-scale sea cages, the behavioral adaptations of this species under such conditions remain insufficiently characterized. To solve this problem, the study implemented an ultrasonic biotelemetry system to monitor the in situ swimming behavior of L. crocea across varying current velocities and tidal phases. The results indicated that the tagged fish predominantly occupied water depths of 1 to 2.6 m, with no observable circular swimming behavior along the cage periphery. Additionally, the spatial distribution of L. crocea within the large-scale cage seemed to correlate with the direction of the current. Furthermore, both the frequency of appearance and swimming speed of L. crocea were higher in the center of the cage compared to the peripheral regions during flood and ebb tides, whereas the opposite trend was observed during slack water. This study provides novel insights into the behavioral ecology of L. crocea in large-scale aquaculture systems. Full article

Extracts from 58 species of corticioid fungi (phylum Basidiomycota), mainly belonging to the orders Hymenochaetales, Polyporales and Russulales, were tested for their inhibitory activity against five species of bacteria: Corynebacterium striatum, Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Twenty-four of the species we analyzed in this study were tested for antibacterial activity for the first time. The fruiting bodies of the fungi were collected from dead wood in the forests of north-eastern Poland, and macerated in methanol. Dried extracts were redissolved in dimethyl sulfoxide and applied to broth cultures of the bacteria, which were then inoculated on agar plates. Noblesia crocea demonstrated moderate inhibitory activity against all five tested bacteria; Amylocorticium subincarnatum, Laxitextum bicolor, Peniophora laeta, P. rufomarginata, Phanerochaete sordida, and Xylobolus frustulatus inhibited four bacterial species. The extracts from 14 fungal species tested were moderately active against only two bacteria, P. aeruginosa and C. striatum; 17 species were active against C. striatum only. The full inhibition was observed with concentrations of extract 25 or 50 mg/mL. Full article

Ciprofloxacin has been extensively utilized in aquaculture due to its remarkable efficacy in preventing and treating bacterial infections in fish animals. However, the widespread application of ciprofloxacin has led to significant residue accumulation, necessitating the development of rapid, sensitive and specific detection methods. In this study, we developed a novel dual-mode quantitative immunochromatographic assay based on a portable reader and a photothermal instrument, enabling on-site ciprofloxacin detection. Under optimized conditions, the portable reader mode (Mode 1) achieved a detection range of 0.1–100.0 ng/L with a limit of detection (LOD) of 0.1 ng/mL. The photothermal instrument mode (Mode 2) achieved a detection range of 0.1–500.0 ng/mL with an LOD of 0.1 ng/mL. The sensitivity and accuracy of the method were validated using an Enzyme-Linked Immunosorbent Assay. This developed method successfully detected ciprofloxacin residues in samples of Parabramis pekinensis, Larimichthys crocea, Channa argus, Carassius auratus and Micropterus salmoides, with satisfactory recovery rates. The results demonstrated excellent specificity and applicability across various fish product matrices, offering a reliable and efficient solution for the on-site monitoring of ciprofloxacin residues in fish products. Full article

This research evaluates the potential spaces of deep offshore waters for cultivating the Larimichthys crocea, analyzing ocean profile temperature data from 2000 to 2022 according to the species’ environmental temperature suitability. There are significant seasonal variations and differences in habitat distributions of different temperature ranges in China’s surrounding waters. The range of maximum living space obtained according to the tolerance temperature shows a trend of being larger in summer and smaller in winter; and the range of viable habitat space obtained based on the suitable and optimal temperature shows a trend of being smaller in summer and larger in winter. Broad areas meeting tolerance temperatures offer broad, yet impractical, site selection options. In contrast, areas with optimal temperatures are limited, which means the availability of ideal site locations is very restricted. Regions consistently within the 20–28 °C range are best for practical site selection. Year-round suitable areas are primarily found at depths of 30 to 90 m in the southern East China Sea and the South China Sea, particularly within the 40 to 50 m depth range. Water mass like the South China Sea Surface Water and the Kuroshio Surface Water consistently maintain suitable temperatures, making them ideal for aquaculture. Full article

To explore the effect of density on large yellow croaker (Larimichthys crocea) under intensive aquaculture conditions and determine the appropriate culturing density, this study investigate the effects of different stocking densities on the nutritional composition, stress, and immune levels of large yellow croaker. Through a long-term aquaculture experiment, conducted under flow-through conditions of intensive aquaculture, three initial density groups were set: a low density group [LD], 4.92 kg/m³; a medium density group [MD], 7.56 kg/m³; and a high density group [HD], 10.08 kg/m³, for a 150-day rearing trial. Large yellow croaker were fed to satiation twice daily (6:00, 17:00). At the end of this trial, the final densities were 10.38 ± 0.50, 14.41 ± 1.06, and 18.71 ± 0.99 kg/m³ in the LD, MD, and HD groups, respectively. The results showed that the growth performances were adversely influenced by a high stocking density. Levels of cortisol in serum, superoxide dismutase (SOD) and catalase (CAT) in liver, Na⁺-K⁺ ATPase and Na⁺-K⁺ ATPase gene in gills, and heat shock protein (HSP70/90) genes and glutathione S-transferase (GST) genes in the liver significantly increased under HD treatment. Results of immune response analyses showed that there was a clear decrease in immunoglobulin M (IgM), complement component 4 (C4), and lysozyme (LZM) in serum, lysozyme (LZM) genes, tumor necrosis factor-alpha (TNF-α) genes and interleukin-1β (IL-1β) genes in the head kidney of large yellow croakers reared in the HD group. An obvious increase in free amino acids and fatty acids in the muscle of large yellow croakers reared in HD group was also observed. Overall, this study showed that the optimal final culturing density of large yellow croaker under flow-through systems should be between 14.41 kg/m³ and 18.71 kg/m³ to improve aquaculture efficiency and product quality. Full article

The sea bivalve clam Tridacna crocea inhabiting the shallow sea of tropical and subtropical zones lives with the symbiotic alga zooxanthella in its mantle. Zooxanthellae algae perform photosynthesis and supply nutrients to T. crocea. Recently, the abundance of T. crocea has decreased rapidly due to overfishing in coastal areas in Okinawa, Japan. T. crocea culture systems for mass production will contribute to the conservation of T. crocea and thus marine ecosystems. Environmental control methods for T. crocea culture have not been established because of a lack of knowledge about the appropriate environmental conditions for T. crocea growth. The present study was initiated to obtain basic data for developing environmental control methods for T. crocea land-based aquaculture. The effects of water temperature, dissolved oxygen concentration, and photosynthetic photon flux density (PPFD) on the O₂ exchange rates of the symbiotic system of T. crocea and zooxanthella, which are indicators of photosynthesis and respiration in the system, and the effect of daily integrated PPFD on T. crocea growth were investigated. Basic knowledge was obtained for the development of optimal environmental control technology for T. crocea clam culture. The optimum water temperature and dissolved oxygen concentration for photosynthesis in this symbiotic system were 28 °C, 5–6 mgO₂ L⁻¹ and 500 μmol m⁻² d⁻¹, respectively. The optimum daily integrated PPFD for clam growth was 20 mol m⁻² d⁻¹. Full article

Soybean meal, renowned for its high yield, cost efficiency, and protein richness, serves as a pivotal plant-based alternative to fish meal. However, high soybean meal inclusion in Larimichthys crocea diets is linked to enteritis and oxidative damage, with unknown mechanisms. Our study aims to elucidate the molecular basis of soybean-meal-induced enteritis and its impact on intestinal microbiota in L. crocea. To this end, four isonitrogenous and isolipidic diets with varying soybean meal levels (0% FM, 15% SBM15, 30% SBM30, and 45% SBM45) were administered to L. crocea for 8 weeks. The results indicated that the SBM30 and SBM45 treatments significantly hindered fish growth, digestive efficiency, and protein utilization. Furthermore, high soybean meal levels (SBM30 and SBM45) activated intestinal Toll-like receptors (TLR2A, TLR2B, TLR5, and TLR22), stimulating C-Rel and mTOR protein expression and elevating ERK phosphorylation. This led to increased pro-inflammatory cytokine production (IL-1β, IL-6, and TNF-α) and decreased anti-inflammatory cytokine expression (IL-4/13A, IL-4/13B, and TGF-β), suggesting a potential signaling pathway for soybean-meal-induced enteritis. Furthermore, enteritis induced by high soybean meal levels led to oxidative damage, evident from increased MDA levels and decreased antioxidant enzyme activities (SOD and CAT). The SBM30 and SBM45 treatments increased Firmicutes and Bacteroidetes abundance in fish gut microbiota, while Proteobacteria abundance decreased. This microbiota shift may enhance soybean meal nutrient utilization, yet high soybean meal concentrations still impair growth. A soybean-meal-rich diet promotes harmful bacteria like Rhodococcus and depletes probiotics like Ralstonia, increasing disease risks. L. crocea has limited tolerance for soybean meal, necessitating advanced processing to mitigate anti-nutritional factors. Ultimately, exploring alternative protein sources beyond soybean meal for fish meal replacement is optimal for L. crocea. Full article

The vasa gene, encoding an ATP-dependent RNA helicase, and the nanos-2 gene, an RNA-binding protein, are essential for germ cell origination, migration, maintenance, and development in vertebrates and invertebrates. The expression levels of the vasa and nanos-2 genes have not yet been investigated or reported in crappie species. These two genes were partially sequenced and characterized, and their expression patterns were analyzed using reverse-transcription quantitative polymerase chain reaction (RT-qPCR) according to age and sex. The vasa sequences of white crappie (WC) females and males showed significant similarity with the vasa homologs of largemouth bass (Micropterus salmoides; 93.1–93.98%) and smallmouth bass (M. dolomieu; 91.95–92.77%), indicating its conserved nature within the Family Centrarchidae. The vasa sequence of black crappie (BC) females showed significant similarity with the vasa homologs of white crappie (91.67%), largemouth bass (96.10%), smallmouth bass (96.10%), spotted scat (Scatophagus argus; 97.37%), mandarin fish (Siniperca chutasi; 96.15%), Japanese sea bass (Lateolabrax japonicus; 94.87%), lumpfish (Cyclopterus lumpus; 91.95%), southern bluefin tuna (Thunnus maccoyii; 94.74%), large yellow croaker (Larimichthys crocea; 92.21%), and Nile tilapia (Oreochromis niloticus; 92.21%). The nanos-2 sequences of WC females, WC males, and BC females showed significant similarity with the nanos-2 of largemouth bass (92.92–96.36%), smallmouth bass (92.92–96.36%), and mandarin fish (92.66–94.34%). The expression of vasa in BC females was significantly higher at age-2 than at age-1, while WC males and females presented no significant age-related differences. Neither species had a significant difference in nanos-2 gene expression with age. The expression levels of vasa and nanos-2 were significantly higher in WC males than females. Full article

Scuticociliates are recognized as the causative agents of mass mortalities in certain cultured marine fishes, resulting in enormous economic losses. This study aimed to investigate a fatal infection caused by scuticociliates in farmed large yellow croaker (Larimichthys crocea) in Fujian province, China. Microscopic examinations of focal organs, including the brain, eyes, gills, and skin, revealed the presence of parasites. Active masses of scuticociliates were observed in these organs, and the ciliates were subsequently isolated and maintained in vitro. An immersion challenge experiment revealed that L. crocea experienced cumulative mortalities reaching 73% within 7 d upon exposure to 1.0 × 10⁴ ciliates mL⁻¹. Based on the microscopic and PCR testing of infected fishes, the brain was comprehensively inferred as the main infection organ for the isolated strain. Microscopic and submicroscopic observations of the isolated scuticociliate, coupled with cortical ciliature patterns revealed through α-tubulin indirect immunofluorescence techniques, identified these scuticociliates as Miamiensis avidus. The sequencing of two genetic markers (small subunit ribosomal RNA, SSU rRNA and cytochrome c oxidase subunit I, COI) further confirmed that the isolated strains exhibited the highest sequence similarity to most M. avidus sequences in GenBank. However, significant differences in SSU sequences compared to the M. avidus strain Ma/2, and the lack of published COI and ITS (internal transcribed spacer) sequences for Ma/2, indicate the need for further molecular data to resolve whether there are potential cryptic species within the M. avidus complex. Full article

Food-derived angiotensin-I-converting enzyme (ACE)-inhibitory peptides have gained attention for their potent and safe treatment of hypertensive disorders. However, there are some limitations of conventional methods for preparing ACE-inhibitory peptides. In this study, in silico hydrolysis, the quantitative structure–activity relationship (QSAR) model, LC-MS/MS, inhibition kinetics, and molecular docking were used to investigate the stability, hydrolyzability, in vitro activity, and inhibition mechanism of bioactive peptides during the actual hydrolysis process. Six novel ACE-inhibitory peptides were screened from the Larimichthys crocea protein (LCP) and had low IC₅₀ values (from 0.63 ± 0.09 µM to 10.26 ± 0.21 µM), which were close to the results of the QSAR model. After in vitro gastrointestinal simulated digestion activity of IPYADFK, FYEPFM and NWPWMK were found to remain almost unchanged, whereas LYDHLGK, INEMLDTK, and IHFGTTGK were affected by gastrointestinal digestion. Meanwhile, the inhibition kinetics and molecular docking results were consistent in that ACE-inhibitory peptides of different inhibition forms could effectively bind to the active or non-central active centers of ACE through hydrogen bonding. Our proposed method has better reproducibility, accuracy, and higher directivity than previous methods. This study can provide new approaches for the deep processing, identification, and preparation of Larimichthys crocea. Full article

Emerging evidence shows that N6-methyladenosine (m6A) is a post-transcriptional RNA modification that plays a vital role in regulation of gene expression, fundamental biological processes, and physiological functions. To explore the effect of starvation on m6A methylation modification in the liver of Larimichthys crocea (L. crocea) under low temperatures, the livers of L. crocea from cold and cold + fasting groups were subjected to MeRIP-seq and RNA-seq using the NovaSeq 6000 platform. Compared to the cryogenic group, the expression of RNA methyltransferases mettl3 and mettl14 was upregulated, whereas that of demethylase fto and alkbh5 was downregulated in the starved cryogenic group. A Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the differentially m6A-modified genes were mainly enriched in steroid biosynthesis, DNA replication, ribosome biogenesis in eukaryotes, PPAR, ECM-receptor interaction, lysine degradation, phosphatidylinositol, and the MAPK signaling pathway, suggesting that L. crocea responds to starvation under low-temperature stress through m6A methylation modification-mediated cell growth, proliferation, innate immunity, and the maintenance of lipid homeostasis. This study advances understanding of the physiological response mechanism exerted by m6A methylation modification in starved L. crocea at low temperatures. Full article

Excess energy derived from photosynthesis can be used in plant microbial fuel cell (PMFC) systems as a sustainable alternative for the generation of electricity. In this study, the in situ performance of CAM (Crassulacean acid metabolism) plants in Calama, in the Atacama Desert, was evaluated for energy recovery using PMFCs with stainless steel AISI 316L and Cu as electrodes. The plant species evaluated included Aloe perfoliata, Cereus jamacaru, Austrocylindropuntia subulata, Agave potatorum, Aloe arborescens, Malephora crocea, and Kalanchoe daigremontiana. Among the plant species, Kalanchoe daigremontiana demonstrated significant potential as an in situ PMFC, showing a maximum cell potential of 0.248 V and a minimum of 0.139 V. In addition, the cumulative energy for recovery was about 9.4 mWh m⁻² of the electrode. The use of CAM plants in PMFCs presents a novel approach for green energy generation, as these plants possess an inherent ability to adapt to arid environments and water-scarce areas such as the Atacama Desert climate. Full article