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At least 19 recordsLinked to original sources
PubMed2026

Impact of Tilapinevirus tilapiae (TiLV) infection on the composition and functional dynamics of gut microbiota in Nile Tilapia (Oreochromis niloticus) (Linnaeus, 1758).

Tilapinevirus tilapiae (TiLV) (formerly Tilapia Lake Virus) is a highly prevalent pathogen capable of inducing significant mortality rates in Nile tilapia (Oreochromis niloticus). The alterations induced by Tilapia Lake Virus (TiLV) in the gut microbiota composition, diversity and functional prediction of Nile tilapia have not been thoroughly investigated. This study investigated the gut microbiota of a healthy control group and a TiLV-infected group of Nile tilapia of size 30 ± 2.45g. The alpha diversity of microbiota was hardly affected by TiLV infection, whereas species richness and beta diversity patterns explained the significant differences between control and TiLV-infected groups. The study highlighted a decline in Cetobacterium and an increase in Mycobacterium in the TiLV-infected group. The phyla, including Firmicutes, Actinobacteriota and Proteobacteria, exhibited a significant increase in the TiLV-infected group, while Bacteroidota and Fusobacteriota decreased substantially. The PICRUSt-based functional gene prediction revealed that TiLV infection had considerably changed the KEGG (Kyoto Encyclopaedia of Genes and Genomes) pathways associated with membrane transport, amino acid metabolism, transcription, carbohydrate metabolism, cellular process and signalling in the gut microbiota of Nile tilapia. The results suggest that the infection by TiLV altered the composition and functional pathways in the gut microbiota of Nile tilapia.

Animals↗
PubMed2026

Uncovering host transcriptional responses to tilapia lake virus (TiLV) through De novo RNA-seq assembly in Nile tilapia, Oreochromis niloticus.

Tilapia lake virus (TiLV) has emerged as an important pathogen that negatively impacts tilapia farming globally. Using RNA sequencing technology, this study investigated the liver transcriptomic profile of apparently healthy and TiLV-infected Oreochromis niloticus from wild. RNA sequence libraries generated 3,356 differentially expressed genes (DEGs), with 1,726 genes that were upregulated. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified 680 different pathways with differential regulation of the metabolic and immune-related pathways indicating that TiLV may interfere in host metabolism and replicate to establish the infection. This study provides transcriptomic insights into the liver responses of naturally TiLV-infected wild O. niloticus and highlights key immune and metabolic pathways associated with viral infection.

Animals↗
PubMed1992

Bioconcentration of atrazine in the banded tilapia, Tilapia sparrmanii.

1. The bioconcentration of atrazine was determined in the liver, muscle, heart, gonads and brain of Tilapia sparrmanii exposed to high concentrations of atrazine. 2. The highest concentrations were recorded in the ovaries (50.6 micrograms/g) and in the liver (40.1 +/- 5.5 micrograms/g). This may be attributed to the higher lipid content of these organs, while the liver also accumulates atrazine as a result of its detoxification function. 3. The bioaccumulation factors for atrazine in the liver, muscle, heart, gonads and brain ranged from 0.9 to 20.0. Bioconcentration of atrazine in banded tilapia was found to be low, even after exposure to external atrazine concentration much higher than detected in natural surface water.

Animals↗
PubMed2026

A duplicated female pathway gene figla-like evolves as the male sex-determining gene in tilapia.

As the largest group of vertebrates, fish exhibit frequent turnover of sex-determining (SD) genes. Here, we assemble a chromosome-level YY red tilapia genome and identify figla-like (figlal) as the SD gene on tilapia linkage group (LG) 1. Integrative phylogenetic and genomic evidence suggests that figlal originated from a tilapia-specific duplication and transposition of the ancestral bHLH family gene figla from LG12 to LG1. Fluorescence in situ hybridization reveals expression divergence between figla and figlal, with figla expressed in female oocytes and figlal expressed in male gonadal somatic cells during early gonadal differentiation. The shift in expression after duplication might be driven by the insertion of cis-regulatory elements mediated by transposable elements. Knockout of figlal in XY fish results in male-to-female sex reversal as indicated by ovarian morphology, down-regulation of the male pathway gene dmrt1, and up-regulation of the female pathway gene cyp19a1a in the gonads. In contrast, overexpression of figlal in XX fish induces female-to-male sex reversal. These findings implicate figlal as an SD gene on tilapia LG1 and reveal the history of a unique evolutionary innovation in which a female oocyte gene evolved into a male SD gene via duplication, transposition, and cis-regulatory rewiring.

Animals↗
PubMed1992

Neurotensin, substance P, gastrin/cholecystokinin, and bombesin in the intestine of the tilapia (Oreochromis mossambicus) and the goldfish (Carassius auratus): immunochemical detection and effects on electrophysiological characteristics.

The distribution of neurotensin-, substance P-, gastrin/cholecystokinin/carerulein- and bombesin-like immunoreactivities has been studied in the gut of the tilapia (Oreochromis mossambicus) and the goldfish (Carassius auratus) using immunohistochemistry and radioimmunoassay; the electrophysiological effects of these peptides on the intestinal epithelium were also examined with the Ussing-type chamber technique. Neurotensin- and gastrin/cholecystokinin/caerulein-like immunoreactivities were present in endocrine cells in both species. Substance P- and bombesin-like immunoreactive endocrine cells were present in the intestine of the tilapia. Neurotensin-like immunoreactivity was observed in varicose fibers and nerve cell bodies in the muscle layers and myenteric plexus of both species, whereas nerve fibers showing substance P-like immunoreactivity were found in the goldfish only. Using radioimmunoassays, neurotensin- and gastrin/cholecystokinin/caerulein-like immunoreactive materials were detected in intestinal extracts of both species. The amounts of substance P- and bombesin-like material were below detection level. The ion selectivity of the intestinal epithelium of both species was modulated by exogenously applied neurotensin. This effect was blocked by tetrodotoxin in the tilapia but not in the goldfish. In the tilapia, neurotensin may act via stimulation of a cAMP-dependent increase of the Cl- conductance of the tight junctions, whereas in the goldfish, neurotensin induced, via an unknown messenger, a transient decrease of the cation selectivity without a decrease in the resistance. Substance P, cholecystokinin, and bombesin were without effect on the electrophysiological characteristics of the epithelium.

Animals↗
PubMed1992

Genetic variability in a family of satellite DNAs from tilapia (Pisces: Cichlidae).

We have cloned and sequenced members of a family of satellite DNAs from three genera of the tilapiine tribe of fishes: Oreochromis, Sarotherodon, and Tilapia. The satellite DNAs, visualized as intensely staining bands following electrophoretic separation of EcoRI-digested genomic DNA, consist of three size variants differentially distributed in the various tilapiine species. The sizes of the monomers are approximately 237 bp (type I), 230 bp (type II), and 209 bp (type III). Several cloned monomers were sequenced from Oreochromis niloticus (type III), Oreochromis placidus (types I and II), Sarotherodon galilaeus (type I), Tilapia zillii (type I), and Tilapia rendalli (type I). Comparison of derived consensus sequences for the monomer units of the satellite DNAs revealed sequence identities within and between species that ranged from 89 to 96%. The type II and type III size variants appear to have arisen by deletions of 9 and 29 bp, respectively, within different regions of the type I satellite. Hybridization of a cloned monomer satellite from O. niloticus (type III) to PalI digests of genomic DNA from all three genera detected polymorphic, high molecular weight restriction fragments that produced fingerprint-like patterns. The complexity of these DNA fingerprints varied from one species to another, suggesting a markedly different genomic organization for these polymorphic satellite DNAs.

Animals↗
PubMed2026

Whole-Genome Sequencing Reveals Virulence and Antimicrobial Resistance Determinants of Lactococcus garvieae Causing Lactococcosis in Cage-Cultured Nile Tilapia (Oreochromis niloticus) in Thailand.

Lactococcosis is an important bacterial disease affecting farmed fish worldwide and is primarily associated with Lactococcus garvieae, Lactococcus petauri, and Lactococcus formosensis. In Thailand, information on L. garvieae infection in tilapia remains limited, particularly regarding genome-based identification, virulence determinants, and antimicrobial resistance profiles. This study characterized two L. garvieae isolates, AAHM-LG2501 and AAHM-LG2509, recovered from a lactococcosis outbreak in cage-cultured Nile tilapia (Oreochromis niloticus) in Ubon Ratchathani province, Thailand. Both isolates exhibited typical phenotypic characteristics of L. garvieae, including Gram-positive cocci, alpha hemolysis, positive capsule staining, and positive carbohydrate fermentation. Whole-genome sequencing confirmed both isolates as L. garvieae, with genome sizes of approximately 1.95 Mb and a G + C content of 38.9%. Genome-based taxonomic analysis supported species identification based on dDDH and ANI values, and both isolates were assigned to sequence type ST95 and serotype I. Virulence factor analysis identified 288 virulence-associated genes representing 97 virulence factors across 14 functional categories. Capsule-associated genes were prominent, together with genes involved in heme uptake, adhesion, hemolysis, stress survival, biofilm formation, and host adaptation. Ten capsule biosynthesis genes, including cpsABCFGKO, cps4A, and cps4I, as well as LPxTG cell wall anchor protein genes, were detected. Antimicrobial susceptibility testing showed resistance to nalidixic acid, oxolinic acid, and oxacillin, while reduced inhibition zones were observed for enrofloxacin and sulfamethoxazole-trimethoprim. Genome analysis identified predicted antimicrobial resistance determinants, including lsaD, vanT, vanY, and mdtA. Resistance-associated protein variants were detected in gyrA and gyrB, suggesting that target alteration may contribute to fluoroquinolone resistance. Overall, this study provides genome-level evidence of virulence and antimicrobial resistance determinants in L. garvieae from Thai tilapia and highlights the importance of whole-genome sequencing for accurate diagnosis, epidemiological surveillance, and disease management in aquaculture.

Animals↗
PubMed2026

Genomic characterization of a hypervirulent Aeromonas veronii NN0115 from Nile tilapia and head kidney transcriptome of infected fish reveals B-cell-dominated immune response with specific immunoglobulin downregulation.

Aeromonas veronii is a pathogen of multiple fish species, yet systematic understanding of its infection in Nile tilapia (Oreochromis niloticus) remains limited. A dominant strain, NN0115, was isolated from a natural outbreak and identified as A. veronii by 16S rRNA and whole-genome average nucleotide identity (ANI, 96.33%). Experimental infection revealed high virulence (LD50 = 3.41 × 106 CFU/mL, equivalent to 8.53 × 104 CFU/fish). The genome is 4.58 Mb (58.57% GC) and encodes 4216 proteins. Virulence factor analysis identified 1253 genes, dominated by motility-related (264) and immune modulation (208) factors. Genomic island GI2 harbors 7 virulence genes and two dual-function resistance-virulence genes. The strain is resistant to 9 of 25 agents tested but carries three RND efflux pump genes whose predicted resistance was not phenotypically observed. The head kidney transcriptome of tilapia at 24 h post-bacterial infection identified 773 differentially expressed genes; among them, 57 were immunoglobulin (Ig) genes, and 56 were down-regulated. Integration of published single-cell transcriptomic data showed that non-Ig B-cell marker genes were down-regulated by 32%, whereas Ig genes were reduced by 63%, indicating selective transcriptional suppression of Ig genes rather than a general decrease in B-cell transcriptional activity. Together, this study provides a comprehensive characterization of a highly virulent A. veronii from Nile tilapia and reveals that selective downregulation of B-cell Ig genes is the dominant transcriptional feature of the host head kidney response.

Animals↗
PubMed2026

Dietary soybean or seaweed (Kappaphycus sp.) modulates taste-related gene (tas1r1 and tas1r2.2) expression in Nile tilapia (Oreochromis niloticus).

Taste perception plays a central role in fish feeding behaviour by influencing feed recognition, intake, and nutrient sensing. As aquaculture increasingly adopts plant-based ingredients to replace fishmeal, understanding how these diets affect gustatory mechanisms is critical. This study evaluated TAS-family taste receptor genes in Nile tilapia (Oreochromis niloticus) fed nutritionally formulated diets containing fishmeal (TFM), soybean meal (TSB), red seaweed (Kappaphycus sp., TSW), alongside a natural meal (TNM) reference. Fish were reared for 62 days under controlled conditions, after which growth performance was evaluated, and tongue transcriptomes were analysed using RNA sequencing to identify diet-associated gene expression changes. Candidate TAS1R and TAS2R receptors were identified through conserved domain screening and phylogenetic validation, and differential expression analysis was performed using DESeq2. Growth performance did not differ significantly among diets, although the soybean group showed the highest weight gain. Under the conditions of this study, most taste-related genes remained transcriptionally stable across formulated diets, indicating limited responsiveness of the gustatory system to ingredient substitution. Transcriptional differences were mainly observed in comparisons involving the TNM (TSB vs TNM and TSW vs TNM), where tas1r1 was upregulated, suggesting altered amino acid sensing relative to the non-formulated diet. Among formulated diets, tas1r2.2 was upregulated in the TSW vs TFM comparison, indicating potential modulation of carbohydrate-related taste pathways associated with seaweed inclusion. No reliable TAS2R transcripts were detected, likely due to low expression or tissue-specific distribution. Overall, taste receptor expression in Nile tilapia appears resilient to dietary variation, with selective modulation of TAS1R genes providing molecular insight into chemosensory adaptation to sustainable feed ingredients.

Animals↗
PubMed2026

Effects of faba bean-based crisping culture on phenotypic characteristics, muscle quality, and serum metabolome in Nile tilapia: Screening biomarkers to assess the degree of crisping.

Feeding Nile tilapia (Oreochromis niloticus) a faba bean-based crisping diet enhances muscle hardness (crispness) and overall flesh quality. However, the underlying mechanisms and reliable biomarkers remain insufficiently defined. This study integrated phenotypic traits, muscle texture, collagen content, serum antioxidant enzyme activities (SOD, CAT, and GSH-Px), MDA levels, and serum metabolomics to understand the determinants of muscle crisping. Fish were assigned to a crisping diet or a control group for 90&#xa0;days. Individuals in the crisping group were implanted with passive integrated transponder (PIT) tags to enable correlation analyses among phenotypic traits (body weight/length/frame changes), serum indicators (NAM, FAD, and GSH-Px) and muscle hardness. Compared with controls, the crisping diet significantly increased muscle hardness, gumminess, and chewiness, accompanied by elevated collagen content. Antioxidant profiles were altered, with higher activities of serum SOD and CAT, together with elevated MDA levels and reduced GSH-Px activity (P&#xa0;<&#xa0;0.05). Metabolomic analysis identified 830 differential metabolites (682 upregulated and 148 downregulated), predominantly comprising carboxylic acids and derivatives, glycerophospholipids, and benzene derivatives. Enrichment analysis indicated significant involvement in general metabolic pathways, ATP-binding cassette (ABC) transporters, amino acid biosynthesis, and glycine, serine, and threonine metabolism (P&#xa0;<&#xa0;0.05). Notably, acetylpyruvate was upregulated in glutathione metabolism, nicotinate and nicotinamide metabolism, and galactose metabolism; pantothenic acid was upregulated in glycine, serine, and threonine metabolism; whereas &#x3b4;-tocotrienol was downregulated. Correlation analysis revealed weak negative associations between muscle hardness and phenotypic traits (body weight/length/frame changes D5-7, D5-10, D7-8) (P&#xa0;<&#xa0;0.05). In contrast, serum NAM and FAD were weakly positively correlated with muscle hardness, whereas GSH-Px showed a weak negative correlation (P&#xa0;<&#xa0;0.05). Collectively, these findings suggest that body weight, body length, frame measurements (D5-7, D5-10, and D7-8), and serum NAM, FAD, and GSH-Px are associated with the degree of muscle crispness in Nile tilapia fed a faba bean-based crisping diet and may serve as candidate biomarkers under these culture conditions.

Animals↗
PubMedDate not supplied

Transgene transmission and expression in rainbow trout and tilapia.

We describe the production of transgenic rainbow trout (Oncorhynchus mykiss) and tilapia (Oreochromis niloticus) by microneedle injection of fertilized eggs with cloned copies of novel gene constructs. Two aspects of the work with transgenic trout are presented; namely, patterns of inheritance of transgenes by the F1 generation following in vitro fertilization of gametes from transgenic and nontransgenic fish, and the degree of DNA methylation of transgenes in different fish and in different tissues of the same fish. Work with transgenic tilapia has been only of short duration, and evidence is presented simply to indicate their transgenic status. Transient expression studies using the bacterial gene chloramphenicol acetyltransferase when driven by fish-derived promoters are also discussed.

Animals↗
PubMed1975

Morphology of lymphoid organs in a cichlid teleost, Tilapia mossambica (Peters).

In Tilapia mossambica organized lymphoid tissues are present in the thymus, head-kidney and spleen, whereas they are lacking in pericardial tissue, liver, mesonephros, intestine and rectum. No lymphoid tissue was observed in the chondrocranium and cartilaginous viscerocranium of young adults. The thymus in Tilapia is encapsulated by thin strands of collagen fibers and consists of outer, middle and inner zones. While middle and inner zones are comparable to the thymic cortex and medulla of higher vertebrates, the homology of the outer zone is not clear. At the anterior end of the thymus, a loose aggregation of lymphocytes without a definite boundary has been observed. The head-kidney is characterized by the presence of lymphoid follicles, a subcapsular sinus, a hilus-like area and lymphatic vessels. The spleen is grossly divisible into white pulp and red pulp; the white pulp contains only a reticular area without definite lymphoid centers and the latter contains predominantly erythrocytes. Morphological changes in the lymphoid organs associated with immune response have been discussed.

Animals↗
PubMed1975

Environmental salinity and sodium and chloride exchanges across the gill of Tilapia mossambica.

10 Freshwater-(FW)-adapted, one-third seawater (1/3 SW)-adapted and seawater (SW) adapted Tilapia mossambica were compared for their branchial Na+ influx and efflux as well as Cl- efflux. Na+ and Cl- effluxes were identical. Rates of effluxes were in 1/3 SW- and in SW-adapted fish 10 times and 200 times higher respectively than in FW specimens. 20 Shock due to handling and transfer to small experimental chambers induced, within 20 to 45 min., a considerable increase in Na+ efflux and a more discrete augmentation of the Na+ influx. 30 Branchial Mg++-and Na+-K+ activated ATPase activities increased significantly upon adaptation from FW to 1/3 SW. No significant increase was apparent upon adaptation from 1/3 SW to SW. 40 The trans-branchial potential observed in SW Tilapia resembled the pattern previously described in other species of teleosts.

Adaptation, Physiological↗
PubMed2026

Transcriptomic responses of gill and intestinal tissues in Nile tilapia (Oreochromis niloticus) to bacterial infection following sequential nanoimmersion and hydrogel-based multivalent vaccination.

Bacterial pathogens, including Flavobacterium oreochromis, Aeromonas veronii, Streptococcus agalactiae, and Edwardsiella tarda, represent major infectious threats to Nile tilapia (Oreochromis niloticus). A multivalent vaccination strategy integrating cationic nanoemulsion immersion with oral hydrogel boosters was developed to investigate tissue-specific immune responses at the transcriptomic level. Gill tissues were collected following immersion challenge and intestinal tissues following intraperitoneal injection challenge, reflecting the physiologically relevant infection biology of each pathogen and the mechanistic rationale of each delivery platform. RNA sequencing (RNA-seq) generated high-quality datasets (mapping rate&#xa0;>&#xa0;81.64%) with strong concordance to quantitative real-time PCR (qRT-PCR) validation (r&#xa0;=&#xa0;0.83). Comparative transcriptomic analysis revealed distinct yet complementary immune signatures between tissues. Gill transcriptomes were enriched in phagosome, focal adhesion, extracellular matrix-receptor interaction (ECM-receptor interaction), and cytokine-cytokine receptor interaction pathways, accompanied by increased expression of major histocompatibility complex class I/II (MHC class I/II), mannose receptor, &#x3b1;V&#x3b2;3 integrin, and calnexin, indicating innate activation, enhanced phagocytic capacity, epithelial barrier reinforcement, and adaptive immune coordination. Intestinal transcriptomes showed predominant enrichment of adaptive immune pathways, including the intestinal immune network for immunoglobulin (Ig) production, Forkhead box O (FoxO) signaling, and mitogen-activated protein kinase (MAPK) signaling, with increased expression of T-cell receptor (TCR), inducible T-cell co-stimulator ligand (ICOS-L), C-X-C chemokine receptor type 4 (CXCR4), and polymeric immunoglobulin receptor (pIgR), reflecting T and B cell coordination, lymphocyte trafficking, and mucosal immunoglobulin transport, alongside innate engagement through phagosome pathway enrichment. Shared upregulation of MHC class II, B-cell receptor (BCR) signaling, integrin alpha M (ITGAM), and immunoglobulin-associated components across both tissues suggests coordinated mucosal immune activation through a conserved immune module, warranting direct experimental validation. Collectively, these findings provide transcriptomic evidence that this vaccination strategy elicits an integrated, tissue-specialized immune response, advancing mechanistic understanding of gill and intestinal immunity in vaccine-induced protection of teleost fish.

Animals↗
PubMed2026

Whole-genome sequence of Streptococcus agalactiae strain GIFTS31 isolated from streptococcosis-infected Nile tilapia in Bangladesh.

Streptococcus agalactiae strain GIFTS31 was isolated from a Nile tilapia infected with streptococcosis in Gazipur, Bangladesh. The draft genome of GIFTS31 comprises 2,039,674 bp with a GC content of 35% and encodes 1,957 predicted protein-coding sequences. The genome sequence provides valuable insights into the pathogenic potential of fish-associated S. agalactiae.

Streptococcus agalactiae↗
PubMed2025

Multi-Omics Platforms Reveal Synergistic Intestinal Toxicity in Tilapia from Acute Co-Exposure to Polystyrene Microplastics, Sulfamethoxazole, and BDE153.

Polystyrene microplastic (MP) and its co-existing contaminants may exert different toxic effects on its surrounding aquatic organisms. In order to detect the intestinal harmful responses, tilapia were subjected to exposure with 75 nm of MPs, 100 ng&#xb7;L-1 of sulfamethoxazole (SMZ), 5 ng&#xb7;L-1 of BDE153, and combinations thereof over periods of 2, 4, and 8 days. Enzymatic assays, transcriptomics, proteomics, and metabolomics were employed to evaluate intestinal histopathological effects. Results showed that significant reductions were observed in ATP, ROS, SOD, EROD, lipid metabolism-related enzymes, pro-inflammatory cytokines (TNF&#x3b1; and IL-1&#x3b2;), and apoptosis marker caspase 3 across all groups at day 8. Histological evaluation revealed diminished goblet cell density, with distinct vacuole formation in the BDE153+MPs group. KEGG pathway analysis highlighted disruptions in endocytosis, MAPK signaling, phagosome formation, and actin cytoskeleton regulation. Proteomic findings indicated notable enrichment in endocytosis (decreased sorting nexin-2; increased Si:dkey-13a21.4), MAPK/PPAR signaling, protein processing in the endoplasmic reticulum (Sec61 subunit gamma), and cytoskeletal modulation (reduced fibronectin; elevated activation peptide fragment 1), with or without SMZ and BDE153. Metabolomic profiling showed significant alterations in ABC transporters, aminoacyl-tRNA biosynthesis, protein digestion and absorption, and linoleic acid metabolism. In summary, these findings suggest that BDE153 and MPs synergistically exacerbate intestinal damage and gene/protein expression over time, while SMZ appears to exert an antagonistic, mitigating effect.

Animals↗
PubMed1992

A freeze-fracture study on the effect of neopybuthrin on the intestinal epithelial cells of Tilapia nilotica.

Freeze-fracture replicas of the plasma membrane and tight junctions (Tj) of intestinal epithelial cells were studied in Tilapia nilotica fish exposed to the pyrethroid insecticide, neopybuthrin. Exposing fishes to different repeated concentrations of 1/2 LC50 of neopybuthrin caused a significant decrease in the population density of IMPs in P- and E-faces. Tight junctions were also affected by neopybuthrin treatment. They appeared fragmented and discontinued, and their strands were fewer in number as compared with controls. Since the structure and number of Tj are major determinants of epithelial permeability, it is postulated that neopybuthrin treatment may affect the intestinal permeability of T. nilotica.

Animals↗