Search Results (71)

Epigenetic regulation plays a central role in shaping innate immune responses following immunostimulant exposure. In this study, we characterized the epigenetic landscape of four histone modifications, H3K27ac, H3K27me3, H3K4me1, and H3K4me3, in the anterior kidney of Ictalurus punctatus (channel catfish) following β-glucan exposure. Using chromatin immunoprecipitation sequencing (ChIP-seq), we generated chromatin state maps and examined the regulatory potential of these histone marks in relation to transcriptional responses. Genes showing increased expression associated with H3K4me3 up-peaks included regulators of metabolism, signaling, pathogen recognition, and immune regulation, while H3K27ac and H3K4me1 marks were linked to genes involved in apoptosis, cytoskeletal dynamics, autophagy, cell adhesion, and stress responses. In contrast, H3K27me3-associated gene repression appeared to fine-tune immune activation by selectively maintaining transcriptional restraint at specific loci. Further transcriptional regulatory-related genes were significantly enriched, suggesting metabolic adaptation following β-glucan exposure. Collectively, these findings define the epigenetic landscape of key histone marks in channel catfish following β-glucan exposure and reveal coordinated chromatin and transcriptional remodeling, consistent with mechanisms of trained immunity. This work provides novel insight into conserved epigenetic features of innate immune memory in teleost fish and supports the use of β-glucan as a functional immunomodulator in aquaculture. Full article

Malondialdehyde (MDA) is a common oxidation product in deteriorated aquatic feed, which easily induces oxidative damage and quality deterioration in farmed fish, yet its systemic effects on the physiological function and body color of channel catfish (Ictalurus punctatus) remain poorly understood. This study aimed to investigate the influences of dietary exogenous MDA on antioxidant capacity, immune function and body coloration of channel catfish. A 30-day feeding trial was carried out with four dietary MDA levels of 0, 22.3, 44.6 and 66.8 mg/kg. Relevant physiological and pigment indices of skin and muscle were determined. Exogenous MDA significantly increased plasma transaminase levels and tissue MDA content, decreased antioxidant enzyme activities, and altered the transcription of antioxidant and immune-related genes in skin and muscle, causing oxidative stress and immune dysfunction. It also suppressed tyrosinase activity, downregulated melanin-synthesis-related genes, reduced melanin deposition and promoted uranidin accumulation in the two tissues. Collectively, dietary exogenous MDA impairs antioxidant and immune performance, disrupts pigment metabolism, and ultimately leads to body yellowing in channel catfish. Full article

Introduction: Longlines are traditional fishing gear and are widely used in marine systems for both quantitative and qualitative sampling of large predators like tuna, swordfish, sailfish, marlin or sharks. This highly selective method has been applied for the sampling of European catfish (Silurus glanis), the largest freshwater fish in Europe. This apex predator is a highly valuable fish species in its native localities of Central and Eastern Europe (commercial fishing, anglers’ trophy fishing, biomanipulation purposes) but a dangerous alien invasive species in South and Western Europe. Objective: The efficiency and selectivity of longlines for European catfish sampling were compared with more traditional fishing methods like gillnets and electrofishing. Methodology: European catfish were sampled in native areas (Římov, Žlutice, Vrchlice, Hubenov, Lipno, Želivka reservoirs; Czech Republic) and areas of invasion (Lakes Campagna, Avigliana Grande, Maggiore; Italy; Belver, Meimoa, Cedillo reservoirs; Portugal; Iznajar, Mequinenza reservoirs; Spain) following the protocols of best catfish (Silurus glanis) capture methodologies in small and large lakes and reservoirs established for the current needs of the European Commission within the LIFE PREDATOR project. Results: The longline efficiency expressed as the proportion of individual hooks catching catfish (live baits exposed overnight) was from low to medium (5–25%; Czech reservoirs, Italian lakes, Meimoa reservoir) to very high (up to over 50%; Portuguese and Spanish reservoirs). In many water bodies, specifically in areas of invasion, catfish represented 100% of the longline catch (Campagna, Maggiore, Cedillo, Iznajar, Mequinenza). In the rest of the water bodies, the by-catch ranged from 2 to 20% with the highest values occurring in its native localities (due to the presence of large individuals of Northern pike, Esox lucius, another predatory fish in these systems). In areas of invasion, the inconsiderable by-catch was composed of other non-native predatory fish species like pikeperch (Sander lucioperca), European perch (Perca fluviatilis) or channel catfish (Ictalurus punctatus). Both the efficiency and selectivity of longlines were higher compared to gillnets and electrofishing, and longlines also caught larger catfish individuals. Conclusions: Longlines represent an efficient and extremely selective method for European catfish sampling, reduction and even eradication, especially in areas of invasion. Their usage, however, requires specific equipment, skills and also baits. Full article

Background: Edwardsiella piscicida is a significant intracellular pathogen of channel catfish (Ictalurus punctatus) and a major threat to U.S. aquaculture. A recently developed recombinant attenuated vaccine strain (χ16016) uses arabinose-regulated murA expression to trigger delayed cell wall lysis in vivo, ensuring biological containment while conferring strong protection against virulent challenge. Although its efficacy has been demonstrated, the host immune programs underlying protection remain incompletely defined. Methods: We used RNA sequencing to characterize tissue-specific transcriptomic responses in the intestines and kidneys of channel catfish at 7 days post-vaccination. Fish were vaccinated with χ16016 by either bath immersion or intracoelomic (IC) injection, and differentially expressed genes and enriched immune pathways were analyzed to determine how the vaccine delivery route shapes systemic and mucosal immune responses. Results: Across comparisons, 19,101 differentially expressed genes revealed pronounced route- and tissue-dependent immune remodeling. As aquaculture vaccination strategies increasingly prioritize scalability and practical deployment, understanding how the delivery route shapes immune outcomes is critical. Here, IC vaccination induced broader systemic transcriptional changes, particularly in the intestine, whereas bath immunization elicited a more focused yet coordinated mucosal response. Overall, intestinal tissue exhibited greater transcriptional responsiveness than kidney tissue, underscoring its central role in early vaccine-induced immunity. Functional enrichment analyses identified the activation of innate recognition pathways, MAPK and calcium signaling cascades, complement components, antigen processing machinery, and cell adhesion networks. Notably, bath immunization enriched the intestinal immune network for IgA production pathway, which represents an orthology-based mapping of conserved mucosal immune components, alongside the upregulation of IL-6, CXCL12–CXCR4, integrins (α4β7), MHC class II, complement C3, and polymeric immunoglobulin receptor (pIgR). Given that catfish rely primarily on IgM in mucosal immunity, these findings indicate the induction of IgM-mediated mucosal defense rather than classical mammalian IgA responses. Concurrent complement and scavenger receptor signatures suggest a transition toward efficient opsonophagocytic clearance with controlled inflammation at this subacute stage. Conclusions: This study provides the first systems-level view of host transcriptomic responses to a regulated-lysis E. piscicida vaccine in channel catfish. The findings demonstrate that immersion vaccination, although transcriptionally less expansive than injection, effectively activates coordinated mucosal innate and adaptive immune programs, supporting its practical use as a scalable vaccination strategy for aquaculture. Full article

The Pearl River Estuary (PRE) is highly vulnerable to alien species invasion due to intense anthropogenic activities in southern China. However, the invasion risk of alien aquatic vertebrates in the PRE remains unclear. In this study, 12 environmental DNA (eDNA) samples were collected from the PRE to reveal the composition and distribution of alien aquatic vertebrates using a vertebrate-universal primer set, and to assess their invasion risks using the Aquatic Species Invasiveness Screening Kit (AS-ISK). We identified a total of nine alien aquatic vertebrate species, including one amphibian (Aquarana catesbeiana) and eight fish species (Coptodon zillii, Oreochromis niloticus, Gambusia affinis, Cirrhinus mrigala, Labeo rohita, Pterygoplichthys pardalis, Ictalurus punctatus, and Neosalanx taihuensis). Notably, six of the nine alien species were detected at eight or more sampling sites, indicating their wide distribution in the PRE. Moreover, all nine alien species were classified as high risk based on AS-ISK, suggesting potential damage to local ecosystems and the aquaculture industry. Our study can help inform policy decisions for the prevention and control of alien aquatic vertebrates in the PRE. Full article

Understanding the genetic architecture underlying growth variation is central to improving aquaculture species through genomic selection. Here, we performed a genome-wide association study (GWAS) on 303 individuals from a G₂ breeding population of channel catfish (Ictalurus punctatus) using whole-genome resequencing data. After stringent quality control, 5.64 million high-confidence single nucleotide polymorphisms (SNPs) were retained for association analyses of two key growth traits—monthly weight gain (MWG) and body depth (BH). We identified 15 and 28 loci significantly associated with MWG and BH, respectively, with the majority concentrated on chromosome 20. Two SNPs (Chr20:14,657,971 and Chr20:14,658,012) located in exon 9 of the rrp44 gene were significantly associated with both traits. Functional annotation and enrichment analyses revealed that the rrp44 gene, encoding an exoribonuclease subunit of the RNA exosome complex, participates in mitotic spindle regulation and post-transcriptional RNA decay, processes critical for cellular growth and metabolic homeostasis. We propose that rrp44 may influence growth through the modulation of feeding rhythm and circadian regulation, providing a potential molecular basis for growth heterogeneity in channel catfish. These findings enrich our understanding of growth-related genomic variation and offer valuable molecular markers for precision breeding and genetic improvement of catfish. Full article

This study aimed to investigate the effects of dietary lipid levels on growth performance and transport stress resistance in large-sized channel catfish (Ictalurus punctatus). Four experimental diets were formulated with fat levels of 7.5% (control), 10.0%, 12.5%, and 15.0%, using soybean oil as the lipid source. Each diet was assigned to four replicate groups in a 110-day feeding trial, with fish averaging 600.61 ± 1.33 g at the start. Results showed that increasing dietary fat enhanced weight gain rate (WGR) and specific growth rate (SGR), with the 15.0% fat group achieving the best growth performance and the lowest feed conversion ratio (FCR), significantly lower than the control (p < 0.05). However, fish fed diets containing 12.5% and 15.0% fat exhibited disorganized hepatocyte arrangement, unclear cell boundaries, and hepatic vacuolization. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities increased initially and then declined with rising fat levels, with the highest values observed at 12.5% fat, significantly exceeding those in the control group (p < 0.05). Furthermore, after simulated transport, the incidence of skin congestion and hemorrhage increased with dietary fat level. Collectively, while higher fat levels improved growth, excessive fat (≥12.5%) compromised liver health and stress resilience. Therefore, a dietary fat level of 10.0% is recommended to balance optimal growth, hepatic integrity, and transport tolerance in I. punctatus. Full article

This study evaluated productive performance, nutrient use efficiency, and nitrogen and phosphorus mass balance in an intensive aquaponic polyculture system combining Nile tilapia (Oreochromis niloticus), channel catfish (Ictalurus punctatus), lettuce (Lactuca sativa), and spinach (Spinacia oleracea) under high biomass density (40 kg m⁻³). Nine treatments were established through a 3 × 3 factorial combination of fish (tilapia:catfish = 75:25, 50:50, 25:75) and plant (lettuce:spinach = 75:25, 50:50, 25:75) species ratios and evaluated over three consecutive 60-day production cycles. Nitrogen and phosphorus use efficiencies differed significantly among treatments, reaching maximum values above 50% for NUE and 47% for PUE in catfish-dominant systems with higher spinach proportions, indicating improved nutrient recovery and reduced losses. These treatments also produced greater fish biomass, whereas lettuce-dominant combinations favored plant yield. Water quality remained within acceptable ranges, although higher catfish proportions were associated with lower dissolved oxygen and increased nitrogen availability. Overall, results demonstrate that optimizing fish–plant species ratios enhances nutrient retention and sustainable productivity in intensive aquaponic systems. Future research should explore adaptive species ratio management and economic feasibility to support large-scale implementation of polyculture aquaponics. Full article

During the summer of 2023, a spontaneous disease outbreak occurred in intensively stocked hybrid catfish (♀ channel catfish, Ictalurus punctatus × ♂ blue catfish, I. furcatus) in earthen ponds on a commercial aquaculture farm in South Texas. The farmer reported 50 to 80 dead fish per pond daily for a month. The fish were market size (1.0 ± 0.3 kg on average), resulting in substantial economic losses. Fifteen moribund fish were submitted for laboratory examination. Grossly, the fish showed distended abdomens, erythematous fins, and inflamed vents. Autopsy demonstrated visceral congestion, distended gastrointestinal tracts, and serosanguineous peritoneal effusion. Bacterial cultures from the internal organs revealed homogeneous bacterial growth after incubation. Presumptive biochemical characterization of the isolated bacteria identified Plesiomonas shigelloides. Further molecular confirmation was achieved by species-specific PCR amplification and 16S-rRNA sequencing. Juvenile catfish were experimentally challenged with the recovered isolates to fulfill Koch’s postulates. Moreover, an antibiogram was performed to evaluate the susceptibility of the isolates to a panel of FDA-approved antimicrobials. P. shigelloides isolates were pathogenic to channel catfish and alarmingly multidrug-resistant. We report here, for the first time, P. shigelloides infection in Texas commercial catfish aquaculture, emphasizing its significance as an emerging enteric pathogen that is difficult to treat with FDA-approved antimicrobials. Full article

To elucidate the temporal dynamics of genetic diversity across successive breeding generations of channel catfish (Ictalurus punctatus) and enhance subsequent breeding efficiency, we systematically evaluated the genetic variation in four consecutive generations using ten highly polymorphic microsatellite loci. The number of alleles (Na), effective alleles (Ne), and Shannon’s index (I) all declined with increasing generations. The mean expected heterozygosity (He) decreased gradually from 0.822 to 0.805 but remained above 0.80, indicating that all generations maintained relatively high genetic diversity. Allele frequency analysis revealed the progressive fixation of alleles potentially linked to target traits, while some rare alleles were gradually lost. Analysis of molecular variance (AMOVA) demonstrated that 98% of the genetic variation occurred within generations, with weak differentiation among generations (Fst = 0.016). UPGMA clustering further indicated that later generations diverged from the base stock, whereas genetic distances among adjacent generations progressively narrowed, suggesting increasing convergence and stabilization of genetic structure. These findings provide both theoretical insights and practical guidance for the continuous selective breeding and germplasm conservation of channel catfish. Full article

Effective transport strategies are critical for the survival and welfare of juvenile Ictalurus punctatus, but the effects of pre-transport salt bath treatments remain uncertain. In this study, we systematically evaluated the effects of pre-transport salt bath acclimation at 0‰ (S1), 1‰ (S2), 5‰ (S3), and 9‰ (S4) salinity for 30 min on stress resilience and recovery in fingerlings during 12 h of simulated transport and 24 h of recovery. All fish survived, but total ammonia nitrogen (TAN) increased, and pH decreased in all groups, except S3, which showed significantly lower TAN and higher pH (p < 0.05). The S3 and S4 groups showed attenuated increases in serum cortisol and glucose, with S3 exhibiting the fastest return to baseline levels and stable serum sodium and potassium levels. Liver antioxidant enzyme activities in group S3 remained stable, with the lowest malondialdehyde (MDA) accumulation. Integrated biomarker response (IBR) and histological analyses demonstrated that S3 had the lowest systemic stress and tissue damage, whereas S1 and S4 displayed marked cellular disruption. These results indicate that a 5‰ salt bath applied prior to transport may improve water quality, mitigate stress responses, and preserve tissue integrity in juvenile channel catfish. Further studies are needed to confirm these findings in other species and under commercial transport conditions. Full article

The innate immune response is an important defense against invading pathogens. Stimulator of interferon gene (STING) plays an important role in the cyclic GMP-AMP synthase (cGAS)-mediated activation of type I IFN responses. However, some viruses have evolved the ability to inhibit the function of STING and evade the host antiviral defenses. Understanding both the mechanism of action and the viruses targets of STING effector is important because of their importance to evade the host antiviral defenses. In this study, the STING (IpSTING) of Ictalurus punctatus was first identified and characterized. Subsequently, the yeast two-hybrid system (Y2HS) was used to screen for proteins from channel catfish virus (CCV, Ictalurid herpesvirus 1) that interact with IpSTING. The ORFs of the CCV were cloned into the pGBKT7 vector and expressed in the AH109 yeast strain. The bait protein expression was validated by autoactivation, and toxicity investigation compared with control (AH109 yeast strain transformed with empty pGBKT7 and pGADT7 vector). Two positive candidate proteins, ORF41 and ORF65, were identified through Y2HS screening as interacting with IpSTING. Their interactions were further validated using co-immunoprecipitation (Co-IP). This represented the first identification of interactions between IpSTING and the CCV proteins ORF41 and ORF65. The data advanced our understanding of the functions of ORF41 and ORF65 and suggested that they might contribute to the evasion of host antiviral defenses. However, the interaction mechanism between IpSTING, and CCV proteins ORF41 and ORF65 still needs to be further explored. Full article

The latest FAO report indicates that aquaculture accounts for 51% of the global production volume of fish and seafood. However, despite the continuous growth of this activity, there is evidence of the excessive use of groundwater in its production processes, as well as pollution caused by nutrient discharges into surface waters due to the water exchange required to maintain water quality in fishponds. Given this context, the objectives of this study were as follows: (1) to review which emergent and floating plant species are used in constructed wetlands (CWs) for the bioremediation of aquaculture wastewater; (2) to identify the aquaculture species whose wastewater has been treated with CW systems; and (3) to examine the integration of CWs with recirculating aquaculture systems (RASs) for water reuse. A systematic literature review was conducted, selecting 70 scientific articles published between 2003 and 2023. The results show that the most used plant species in CW systems were Phragmites australis, Typha latifolia, Canna indica, Eichhornia crassipes, and Arundo donax, out of a total of 43 identified species. These plants treated wastewater generated by 25 aquaculture species, including Oreochromis niloticus, Litopenaeus vannamei, Ictalurus punctatus, Clarias gariepinus, Tachysurus fulvidraco, and Cyprinus carpio, However, only 40% of the reviewed studies addressed aspects related to the incorporation of RAS elements in their designs. In conclusion, the use of plants for wastewater treatment in CW systems is feasible; however, its application remains largely at the experimental scale. Evidence indicates that there are limited real-scale applications and few studies focused on the reuse of treated water for agricultural purposes. This highlights the need for future research aimed at production systems that integrate circular economy principles in this sector, through RAS–CW systems. Additionally, there is a wide variety of plant species that remain unexplored for these purposes. Full article

Aquaculture has become a crucial component of global food production, yet catfish (10.8% of global finfish production) breeding programs often lack sufficient genetic data to fully utilize their production potential. In the last 15 years, there have been improvements in this field as two high-density (HD) single nucleotide polymorphism (SNP) arrays (250K and 690K) and low-density panels have been developed for North American channel catfish (Ictalurus punctatus) and blue catfish (Ictalurus furcatus). This lack of genomic tools hinders genetic improvement efforts in other commercially relevant catfish species besides them. Therefore, this review investigated the reason behind the lack of SNP chip usage in genetic-based selections in most catfish breeding programs and the cross-species applicability of the already existing high-density SNP arrays for genotyping members of the Clariidae, African catfish (Clarias gariepinu), and Siluridae, European catfish (Silurus glanis), families. This paper systematically reviews the literature of more than 16 SNP arrays, with 66 non-target species, and assesses the possibility of adapting catfish SNP arrays to the catfish families of interest. With lowered filtering (e.g., MAF > 0) thresholds, the Affymetrix Axiom 250K and Axiom Catfish 690K Genotyping Array could potentially be used on important market species like African and European catfishes. In the long term, chip development would be the solution for these species, but, until then, cross-application is a viable alternative. Despite low polymorphic SNPs (~1%) and call rates (~0%), this SNP array could aid researchers and breeders, improving catfish aquaculture and management. Full article

Rhythms, regulated by core clock genes like the period (per) gene family, are crucial for maintaining physiological processes in animals. In teleost fish, including channel catfish (Ictalurus punctatus), these genes have evolved distinct functions. However, the evolutionary characteristics and functional roles of period genes, particularly in response to environmental cues such as feeding, remain unclear. This study aimed to investigate the evolutionary divergence and functional specialization of the period gene family in channel catfish, with a focus on feeding-induced rhythmicity. Four period genes, Ipper1b, Ipper2, Ipper2l, and Ipper3, were identified in channel catfish. Phylogenetic analysis revealed distinct evolutionary paths for these genes, with Ipper2l forming a separate clade from Ipper2. Tissue-specific expression analysis showed differential expression of period genes across tissues, with Ipper1b exhibiting the highest expression in the intestine and Ipper2 being predominantly expressed in the liver. Statistical analysis confirmed significant differences in the expression levels between tissues (p < 0.05), supporting the tissue-specific roles of these genes. Notably, under strict feeding schedules, we observed significant modulation of rhythmic expression in both the brain and liver, with a notable shift in the peak expression times and amplitude changes aligned with the feeding time. These results suggest that feeding serves as a critical Zeitgeber, entraining circadian rhythms in key tissues and potentially enhancing metabolic efficiency. These results demonstrated that feeding schedules play a key role in modulating circadian gene expression in channel catfish. This study provides insights into the evolutionary divergence and functional roles of the period gene family in channel catfish, showing how feeding schedules modulate circadian gene expression in the brain and liver. These findings have potential applications in optimizing feeding strategies for improving fish health and growth in aquaculture. Full article