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Silver pomfret, an economically important fish species, encounters significant challenges posed by copper pollution in wild and culturing environment. High level of copper has the potential to accumulate in aquatic organisms over prolonged exposure periods. The extracellular matrix, which is highly susceptible to copper, encompasses various proteins, among which tenascin (TN) might play a crucial role in potentially regulating copper-induced apoptosis. To investigate this hypothesis in fish, we initially identified six TN family members in silver pomfret, namely TNCa , TNCb , TNR , TNXB , TNXBa and TNN. Phylogenetic analysis showed four gene subfamilies, namely TNC, TNR, TNN, and TNX, through comparative analysis with TNs from seven other teleost fish species. Subsequently, we analyzed transcriptome of silver pomfret under copper stress and found differential expression of TN family genes under varying levels of copper stress, particularly TNCa. KEGG enrichment analysis demonstrated a significant enrichment of TN downstream pathway, specifically the Pi3K-AKT signaling pathway. RT-qPCR results indicated up-regulation of TNs and apoptosis inhibition-related genes and down-regulation of apoptosis promotion-related genes within this pathway. Hence, we speculated that TN inhibits copper-induced apoptosis by modulating this particular pathway. To further validate this hypothesis, we established a copper stress cell model using a silver pomfret kidney cell line (PaK) and utilized siRNA to knock down TNCa expression within this cellular model. Comparing RNAi-Cu group to NC-control group, we observed significantly reduced cell viability and intensified apoptosis signals in the former. Additionally, RNAi-Cu group displayed down-regulation of apoptosis inhibition-related genes and up-regulation of apoptosis-related genes in Pi3K-AKT signaling pathway compared to NC-Cu group. These findings indicated that TN might be able to inhibit copper-induced apoptosis through Pi3K-AKT signaling pathway. Ultimately, this study offers foundational knowledge for exploring heavy metal toxicity effect on fishes and some references for utilization of copper in parasite control. [Display omitted] • We initially identified six tenascin family members in silver pomfret. • Phylogenetic analysis revealed four tenascin subfamilies in silver pomfret. • TN can inhibit copper-induced apoptosis through the Pi3K-AKT signaling pathway. [ABSTRACT FROM AUTHOR]

Nocardia seriolae , a widespread opportunistic pathogen, has the ability to infect various economically farmed fishes, leading to prolonged disease courses and high mortality rates. In our current study, we focused on the silver pomfret (Pampus argenteus) and examined the liver, spleen, and kidney tissues at three specific N. seriolae infection phases: control (0 day), L group (infection for 5 days), and H group (infection for 15 days). Utilizing HE staining, we observed typical granulomatous nodules displaying stratified concentric layers, including caseous necrotic cells, epithelioid cells and multinucleated giant cells, fibroblasts and fibrocyte envelopes. The TUNEL assay revealed a significant presence of apoptotic cells concentrated within the renal nodules. Following the infection, there was a noticeable increase in AKP, ACP, and LZM levels in all tissues, while LPS exhibited a consistent decline. Through combined analysis of WGCNA and KEGG pathways derived from the tissue transcriptome, we identified several highly enriched pathways, such as the PI3K-Akt signaling pathway and p53 signaling pathway, in all three tissues. Key DEGs from these pathways underwent further investigation through RT-qPCR. In comparison to the control group, the L group exhibited up-regulation of genes associated with biosynthesis catabolism, whereas genes related to immune response, apoptosis, and ion transport displayed down-regulation. Interestingly, the H group showcased a stark reversal of this trend. To validate these DEGs expressions in vitro, we established a Pampus argenteus spleen cell line (PaS). By evaluating the invasion metrics of NS into PaS, we determined an optimal invasion threshold of 105 CFU/ml. The TUNEL assay demonstrated a notable presence of apoptotic signals in the 5 h and 7 h treatment groups. JC-1 assays indicated a gradual decline in membrane potential starting from the 3-h mark. As the duration of treatment increased, RT-qPCR and IHC findings highlighted an initial up-regulation followed by a subsequent down-regulation of genes associated with biosynthesis catabolism. In contrast, genes related to innate immunity displayed up-regulation, whereas genes related to adaptive immunity and ion transport exhibited an initial surge followed by a gradual decrease. Additionally, genes inhibiting apoptosis showed down-regulation. In conclusion, these findings provide valuable insights into the apoptosis mediated by N. seriolae in piscine hosts. These effects are potentially attributed to the increased expression of ion transport-related genes. Moreover, our study sheds light on the intricate molecular mechanisms underlying piscine immunological responses throughout the entire infection timeline, offering promising opportunities for disease control. • N. seriolae infection caused quintessential granulomatous nodules. • Many apoptotic cells centrally located within the renal nodules. • The weakening of metabolism declined acquired immunity after N. seriolae infection. • We constructed the spleen tissue cell line of silver pomfret. • The apoptosis caused by N. seriolae might be related to ion transport. [ABSTRACT FROM AUTHOR]

A 20 days feeding experiment and 15 days reversed feeding experiment were conducted to study the growth of Pampus argenteus juveniles under different feeding strategies. A total of 900 juveniles (an average ± SD, 5.88 ± 0.98 cm and 5.69 ± 0.64 g) were divided into three feeding groups and the experiments run in triplicate. Each experimental tank contained 1000 L of water and each group was fed to satiation four times a day. Three groups were constructed: group A (fed with 100% jellyfish), group B (fed with 100% Yubao 5# feed), and group C (fed with 50% jellyfish and 50% Yubao 5# mixed feed). The remaining 200 healthy individuals respectively in groups A and B were removed following the 20 days feeding experiment and subjected to 15 days of reverse feeding, resulting in group A' (fed with 100% Yubao 5# feed) and group B′ (fed with 100% jellyfish). Yubao 5# feed is 42% protein while live jellyfish larvae with a 1–2 cm umbrella diameter contain approximately 10% protein content. After 20 days, the results showed similar growth performance in terms of weight gain and specific growth rate (P > 0.05) for group A and B, indicating that the P. argenteus juveniles were able to survive on a jellyfish diet. However, the juveniles in group C showed significant (P < 0.05) weight gain and specific growth rate (8.96 ± 0.77 and 4.739 ± 0.572, respectively) over the same culture period. Serine protease (SP) was selected to study the detoxification mechanism of P. argenteus that were fed on jellyfish, and the SP enzyme activities, mRNA, and protein expression under different culture conditions were analyzed to illustrate the detoxification effect of SP protease on jellyfish toxin. The results showed that the highest SP enzyme activities occurred in the kidneys, liver, stomach, lateral capsules, caecum, and intestine (P < 0.05), with enzyme activity in the order group A > group C > group B, group A > A', and group B′ > B (P < 0.05). The highest enzyme activity of 188.91 UL /L was observed in group A when P. argenteus were fed jellyfish exclusively for 20 days (P < 0.05). The results indicate that jellyfish were the main contributors to the changes observed in the SP mRNA, protein, and enzyme activities. Our results indicate that P. argenteus juveniles can survive when feeding only on jellyfish and grow more rapidly when 50% jellyfish is added to the feed than when fed with jellyfish or Yubao 5# feed alone. SP enzymes, which are sensitive to jellyfish, play an important regulatory role in the digestion and decomposition of jellyfish by P. argenteus , and the kidneys are the most important organ for the detoxification and regulation of jellyfish toxin. • Pampus argenteus juveniles are able to maintain growth by feeding only on jellyfish. • Addition of jellyfish to feed significantly improves the growth of Pampus argenteus. • Serine protease in the kidney of Pampus argenteus plays a detoxifying role against jellyfish toxins. [ABSTRACT FROM AUTHOR]

Due to their high-water content and low nutritional value, jellyfish have long been considered 'dead ends' in marine food webs. However, it was revealed that silver pomfret (Pampus argenteus) preferentially hunts jellyfish, and consuming jellyfish alters intestine histology. To better understand the physiological responses of midgut tissues after consuming jellyfish, we compared the transcriptomes and proteomes of jellyfish-fed and jellyfish-unfed groups, and identified 1167 differentially expressed genes (DEGs) and 471 differentially expressed proteins (DEPs). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that unsaturated fatty acid metabolism pathways, especially cholesterol metabolism, were the most enriched biological pathways. Apolipoprotein E was downregulated at both transcriptome and proteome levels, and it was found to negatively regulate jellyfish consumption. These results provide deep insight into the molecular mechanisms regulating jellyfish consumption in Pampus argenteus. • Eating jellyfish has a dramatic impact on the gut histology of silver pomfret. • Only 29 DEGs and DEPs overlapped. • Cholesterol metabolism plays a central role after consuming jellyfish. • ApoE negatively regulates jellyfish consumption. [ABSTRACT FROM AUTHOR]

Abstract: The fatty acid reserves of broodstocks profoundly affect the fecundity of spawners as well as the quality of the newly hatched larvae. Investigation of the lipid and fatty acid changes in wild-caught broodstocks during the reproductive season should elucidate the most effective strategy with which to enrich broodstocks in artificial breeding programs. This paper investigated the lipid and fatty acid compositions of wild broodstocks of silver pomfret, Pampus argenteus, caught at the Zhoushan fishery ground during the reproductive season. The results indicated that there were significant differences in lipid content among gonad, muscle and liver; mean lipid levels in ovary, testis, liver and muscle were 41.85%, 18.54%, 27.80% and 32.31%, respectively. The lipid content in gonads at developmental stages III–V was relatively more stable than that in muscle or liver, although the lipid level increased in ovary and decreased in muscle as the female broodstocks developed from phase III to phase V. There were significant differences in fatty acid levels among broodstock ovary, testis, muscle and liver. The dominant fatty acids in ovary were as follows: 18:1n−9 (16.91%)>DHA (docosahexaenoic acid) (15.46%)>16:4n−3 (13.14%)>16:0 (12.65%)>EPA (eicosapentaenoic acid) (6.46%)>16:1 (5.34%). In female broodstock liver and muscle, the dominant fatty acids were 16:0 (36.42%)>18:1n−9 (23.26%)>18:0 (7.50%)>16:1 (6.98%)>14:0 (5.10%)>DHA (4.98%) and 18:1n−9 (26.35%)>16:0 (24.07%)>DHA (8.38%)>16:1 (6.62%)>18:0 (5.48%)>14:0(4.44%), respectively. The dominant fatty acids in testis were as follows: DHA (29.84%)>16:0 (23.93%)>18:1n−9 (8.78%)>18:0 (7.98%)>EPA (7.96%)>ARA (arachidonic acid) (3.24%). In the liver and muscle of male broodstocks, the dominant fatty acids were 16:0 (30.14%)>18:1n−9 (25.54%)>18:0 (8.24%)>16:1 (7.24%)>14:0 (5.20%)>DHA (4.75%) and 18:1n−9 (29.51%)>16:0 (23.90%)>DHA (7.80%)>18:0 (6.34%)>16:1 (6.22%)>14:0(3.88%), respectively. The n−3PUFAs and n−3/n−6 ratios in ovary and testis of the broodstocks were significant higher than those in the liver and muscle of the broodstocks. The changes in fatty acid composition in ovary and testis as the broodstocks developed from phase III to phase V were smaller in magnitude than those in muscle or liver. It is therefore suggested that the lipid preferentially transferred to ovary from muscle during the reproductive season, and the PUFAs, such as DHA, EPA, 16:4n−3 and ARA, were selectively transferred to, and conserved in, the ovaries of silver pomfret broodstocks. [Copyright &y& Elsevier]

Abstract: Sub-adults of silver pomfret (Pampus argenteus), produced and reared in the mariculture experimentation facilities of Mariculture and Fisheries Department of Kuwait Institute for Scientific Research (KISR), suffered 55–70% mortalities due to scuticociliatosis by Uronema sp. The parasitic infestation was noticed during April–May 2005. Affected fish showed varying levels of tissue damage including severe epidermal and dermal necrotic lesions. The disease occurred with the raise in water temperature from 20 to 22 °C during April. Loss of scales, appearance of bleached spots that coalesced to form brownish patches, haemorrhagic and severe dermal necrotic lesions were the major clinico-pathological manifestations. The parasite was found abundantly in the blood, peritoneal fluid and the cerebrospinal fluid, the skin and the gill wet mounts. Extensive fouling, necrotic degeneration of the gill epithelium and deep dermal necrosis resulted in mortality of the infected fish. The parasite was noticed in the lumen of the collecting ducts of the kidney and the alimentary canal. The parasite was also seen distributed extensively in the entire brain causing widespread nerve necrosis. Earliest separation of the clinically normal fish from the affected fish resulted in significantly higher survival. The investigations are of significant importance in view of the mariculture potentials of the fish especially after the success of captive spawning and larval rearing achieved by the KISR. [Copyright &y& Elsevier]