Search Results (95)

The results of the trawl survey of the research vessel Professor Kaganovsky over four seamounts (Annei, Jingu, Ojin, and Koko) of the Emperor Seamount Chain in 2019 are presented. Seventy-three species of pelagic and bottom-dwelling cartilaginous and bony fishes from 40 families were collected. Morphological diagnoses are presented for each species, with taxonomic comments for the poorly known taxa. The obtained collection includes 11 species new to science or of uncertain taxonomic position, 9 species newly reported for the Emperor Seamounts, and one new record Linophryne arborifera for the Pacific Ocean. For individual seamounts, 27 fish species were recorded for the first time at Annei, 12 species at Ojin, 4 species at Koko, and 2 species at Jingu Seamounts. Cytochrome c oxidase subunit I (COI) or cytochrome b (Cyt b) sequences were obtained for 36 species belonging to 22 families, including 13 species for which the barcode was flagged for the first time and the sequences made available. Cryptic diversity was revealed within the genera Cyclothone, Argyropelecus, and Chauliodus. According to our data, a boundary between the boreal and subtropical fish communities was found between Nintoku and Jingu Seamounts, with a transitional zone over Jingu and Ojin Seamounts at 37–39° N. However, the distribution of the subtropical species to the north may be limited by the increasing of summit depths in the northern subsection of the chain rather than any oceanographic or climatic barriers. Full article

Serum lectins in vertebrates play crucial roles in innate immunity as recognition molecules for pathogen-associated molecular patterns (PAMPs). In mammals, two major lectins, mannose-binding lectin (MBL) and ficolin, both containing N-terminal collagen-like domains, activate the lectin pathway of complement. While MBL and ficolin recognize distinct PAMPs, their counterparts in teleosts are less understood. To date, MBL and galactose-binding lectin (GalBL) have been identified in teleosts, but the presence of ficolin remains unclear. In this study, we purified a 31-kDa serum lectin from common carp that displayed carbohydrate-binding specificity similar to that of mammalian ficolin. Unexpectedly, this lectin lacked an N-terminal collagenous domain and showed the highest similarity to mammalian microfibril-associated glycoprotein 4 (MFAP4), suggesting that the lectin is distinct from fibulin. Biochemical analyses revealed that carp MFAP4-like lectin (MFAP4Lec) protein forms a hexamer in serum, specifically binds GlcNAc and GalNAc, and recognizes the fish pathogen Vibrio anguillarum. The binding was competitively inhibited by GlcNAc but not by EDTA, indicating Ca²⁺-independent recognition. These findings suggest that MFAP4Lec functions as a novel serum lectin in teleost fish, serving as a recognition molecule for bacterial pathogens in innate immunity. Full article

The lipopolysaccharide (LPS)-induced inflammation model is widely used in mammalian studies but remains poorly investigated in a variety of fish species. We reproduce this model in rainbow trout, Oncorhynchus mykiss, a species of high economic value, to validate specific inflammatory biomarkers for reliably assessing the health and immune status of farmed fish. The inflammatory process, together with the effect of preconditioning, was modeled using two consecutive intraperitoneal injections of 300 and 600 µg LPS. We assessed innate immunity biomarkers, including the expression of inflammation-related genes (il1ß, il8), peripheral blood leukocyte profiles, serum bactericidal activity (SBA), and various serum and hepatic biochemical parameters. These parameters comprised the concentration of C-reactive protein (CRP, an acute phase protein), and the activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione-S-transferase) measured at 24 and 96 h post-injection. In trout, LPS-induced effects involved the overexpression of pro-inflammatory interleukins (il1ß, il8), a left shift in white blood cells (characterized by a prevalence of immature neutrophils), and enhanced SBA. In contrast to warm-blooded animals, LPS challenge in trout did not appear to significantly elevate CRP levels or antioxidant enzyme activity. Further investigations in other fish species are needed to determine whether these are traits specific to trout or common to bony fish. Our findings provide a foundation for developing a biomarker panel suitable for the routine assessment of welfare, early detection of infection-associated inflammation in cultured fish, and the screening of the anti-inflammatory and immunostimulant activities of drugs and feed additives. Full article

Τhe trophic ecology of Pterois miles in the Mediterranean Sea was performed by integrating data from stomach contents (SCA) and stable isotopes analyses (SIA), based on samples caught off the Greek island of Rhodes, SE, Aegean Sea, for the first time. This combined approach provides information on ingested (SCA) and assimilated (SIA) food and thus allows for the depiction of predator–prey relationships. Specimens of devil firefish, including both juveniles and adults (total length of analyzed specimens spanned from 11.40 to 31.50 cm), were collected from different sites around Rhodes. Their diet consisted of bony fish, cephalopods, crustaceans, and gastropods. The δ¹³C and δ¹⁵N values ranged from −18.0 ‰ to −14.4 ‰ and from 7.2 ‰ to 9.2 ‰, respectively. SIA data allowed for the estimation of the trophic position of devil firefish from Rhodes Island, which showed a mean value of 3.1 ± 0.6 and confirms that the species primarily relies on a benthic baseline. Further, our isotopic values approach those obtained in North Carolina and Bermuda, confirming its role as a mesopredator in the Mediterranean benthic food webs. Although preliminary, such results can provide an important baseline for future investigations on the species and the potential impact on the Mediterranean food webs. Full article

Background/Objectives: The butterfish Stromateus stellatus is undervalued and usually discarded as bycatch, leading to an inefficient and unsustainable use of marine biomass. Overall, although Stromateus is the type genus of the family Stromateidae, its species are less studied than more economically important fishes. Methods: In this study, we determined and analyzed the complete mitochondrial genome sequence of S. stellatus. Furthermore, we performed maximum likelihood and Bayesian inference analyses to infer the phylogenetic relationships among 21 species of the order Scombriformes. Results: Using next-generation sequencing (NGS) and de novo assembly, a circular mitochondrial genome of 16,509 bp was obtained, exhibiting the typical vertebrate mitochondrial structure comprising 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. Three intergenic regions were identified, including the control region and the origin of light-strand replication, along with several gene overlaps. The heavy strand nucleotide composition was determined to be 28.79% A, 27.84% C, 16.32% G, and 27.05% T, with a GC content of 44.16%. The three Peprilus and five Pampus species formed a clade together with S. stellatus, supported by high bootstrap and posterior probability values, confirming the monophyly of Stromateidae. Conclusions: The gene order and content are consistent with those reported for other Stromateidae species and correspond to the typical arrangement observed in most bony fishes. This mitochondrial genome represents the first one reported for the genus Stromateus, providing valuable insights into the genetic makeup of S. stellatus, contributing to a better understanding of marine biodiversity. Additionally, these data will support future research on pelagic fish evolution and assist in sustainable fisheries management. Full article

Hypoxic stress is an important environmental challenge for aquatic organisms, which is detrimental to fish survival and growth. Specifically, the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) has emerged as a pivotal regulator, with accumulating evidence underscoring its central role in inflammatory processes. However, the regulatory functions of NLRP3 during hypoxic stress in fat greenling (Hexagrammos otakii) remain elusive. In this study, we systematically analyzed the molecular features of HoNLRP3 and elucidated its biphasic regulatory mechanism under hypoxic stress in H. otakii using phylogenetic analysis, qRT-PCR, Western blot, and immunofluorescence. Its phylogeny is significantly different from that of mammals and carries FISNA and related motifs specific to bony fishes. Hypoxia induced predominant nlrp3 expression in the brain, peaking at 12–24 h, with strong positive correlation to hif-1α activation. NLRP3-ASC-Caspase1 inflammasomes assembly drove IL-1β maturation, while prolonged hypoxia (48 h) activated Caspase3/GSDME-mediated pyroptosis, accompanied by elevated LDH activity. Reoxygenation partially reversed inflammatory and pyroptosis markers, indicating that NLRP3 balances defense and injury through a biphasic regulatory mechanism. This study provides new insights into the hypoxic adaptation mechanisms in bony fish. Full article

Background: The interleukin-10 (IL-10) signaling system, comprising ligands (IL-10s) and receptors (IL-10Rs), plays critical roles in immune regulation, inflammation resolution, and disease pathogenesis. “IL-10 signaling system” here refers to the immunomodulatory signaling system composed of ligands (IL-10s) and receptors (IL-10Rs), which belong to different Protein families in evolution, but achieve functional synergy through the conserved JAK-STAT pathway. Understanding their evolutionary and functional dynamics is essential for elucidating immune mechanisms and therapeutic targeting. Methods: Through phylogenetic reconstruction, homology analysis, and sequence alignment across >400 animal species, we traced the evolutionary trajectory and structural–functional diversification of IL-10s and IL-10Rs. Results and Conclusions: IL-10 signaling components emerged in early vertebrates, with IL-10Rs originating in cartilaginous fishes (~450 Mya) and IL-10s diversifying in bony fishes (~400 Mya). Functional divergence yielded immunosuppressive (IL-10), barrier-protective (IL-20 subfamily), and antiviral (type III IFN) subgroups. Structurally, conserved motifs (e.g., IL-10R1 GYXXQ, IL-22 N54-glycosylation) underpin receptor–ligand binding and JAK/STAT signaling. Evolutionarily invariant residues suggest candidate therapeutic epitopes. This study provides an evolutionary framework highlighting functional conservation and species-specific adaptation within IL-10 signaling, with implications for immunotherapy and animal breeding. Full article

Catsharks are benthic elasmobranchs that share spatial niches with littoral and demersal bony fishes. The genus Schroederichthys includes five species, two of which, S. chilensis and S. bivius, occur in the waters of Chile. These species are morphologically similar and are often misidentified because of their overlapping external features and color patterns. To improve species discrimination, we analyzed the egg case morphology of both species based on 36 egg cases (12 S. chilensis, 24 S. bivius) collected from gravid females captured as bycatch in artisanal fisheries between Iquique and Puerto Montt (July–December 2021). Nine morphometric variables were measured and standardized using the total egg case length. Although the egg cases were similar in general appearance, multivariate analyses revealed significant interspecific differences, with egg case height and anterior border width emerging as the most diagnostic variables. Linear discriminant analysis achieved a 100% classification accuracy within this dataset. To confirm species identity, 24 tissue samples (12 per species) were sequenced for the mitochondrial cytochrome c oxidase subunit I (COI) gene. The haplotypes corresponded to previously published sequences from Chile (S. chilensis) and Argentina (S. bivius), with reciprocal monophyly and 100% bootstrap support. While COI barcoding provided robust confirmation, the core contribution of this study lies in the identification of species-specific egg case morphometrics. Together, these findings establish a dual-track toolkit, egg case morphology for primary discrimination and COI barcodes for confirmatory validation, that can be incorporated into bycatch monitoring and biodiversity assessments, supporting the conservation of poorly known catsharks in the Southeast Pacific. Full article

Mercury (Hg) is a global health concern due to its prevalence, persistence, and toxicity. Numerous studies have assessed Hg concentrations in seafood, but variability in reported concentrations highlights the need for continued monitoring and stricter regulations. We measured total Hg (tHg) in 148 pre-processed, packaged seafood products purchased in Raleigh, North Carolina, using thermal decomposition–gold amalgamation atomic absorption spectrophotometry. Products were grouped into three categories based on trophic ecology and physiology: (1) tuna, (2) other bony fish, and (3) shellfish and squid. Among tuna, albacore had the highest average tHg (396.4 ng/g ± 172.1), while yellowfin had the lowest (68.3 ng/g ± 64.7). Herring (54.0 ng/g ± 23.2) and crab (78.2 ng/g ± 24.1) had the highest concentrations in the other two groups. One can of albacore exceeded the FDA action level of 1 part per million (1.3 ppm or 1300 ng/g). Brand differences were significant for both albacore and light tuna, with Brand 1 consistently showing higher Hg levels. Comparisons to FDA data (1990–2012) suggest Hg concentrations in tuna have remained stable over the past two decades. This study underscores the variability of Hg concentrations across species and brands and the need for continued monitoring to protect consumers. Full article

Otoliths are common in the fossil record and can provide important insight into the evolution and spatial and stratigraphic distribution of fishes, but have remained understudied in many areas of the world. Here, we describe the first marine otolith assemblage from East Africa. The material is from Tanzania Drilling Project cores of late Eocene to early Oligocene age, spanning the Eocene-Oligocene transition (EOT). The assemblage consists of 10 identifiable species of which 5 are new, and 4 remain in open nomenclature. The new species are as follows: Protanago africanus, Bregmaceros tanzaniensis, Ortugobius pandeanus, “Serranus” plasmaticus, and Acanthocepola signanoae. The association of shallow and deep-water taxa along with the dominance of the family Cepolidae, which has not been observed in either the extant or fossil record, makes the faunal composition unusual. However, when taxon occurrences are correlated with stable isotope records from the same cores and compared with previous studies, it is clear the otoliths reflect the sea-level fall known to occur during the EOT, with deeper dwelling taxa in the late Eocene and taxa preferring shallower, which are more shelf-like environments in the early Oligocene. Full article

Stings from venomous bony and cartilaginous fishes are known to cause extreme pain in humans, and with changing migratory patterns and distributions due to climate change, human interactions with venomous fishes may increase. Therefore, developing a better understanding of venomous fish stings and the associated pain can provide better solutions for first aid and treatments, particularly in areas or within populations with a higher risk of being stung. Using the results from an online questionnaire, this study discusses the perspectives of 121 people with direct experience of fish stings, exploring the contexts in which fish stings occurred, their firsthand experiences of pain, sting pathophysiology, experiences with medical treatments, and the long-term consequences of fish stings. This small-scale survey has proved successful for the exploration of fish sting experiences, and as such, an approach of this nature should be considered to better understand victim’s experiences with other painful animal stings. Full article

The lateral line system in fish is crucial for detecting water flow, which facilitates various behaviors such as prey detection, predator avoidance, and rheotaxis. The cupula, a gelatinous structure overlaying the hair cells in neuromasts, plays a key role in transmitting mechanical stimuli to hair cells. However, the molecular composition of the cupula matrix remains poorly understood. In this study, we found that Mucin-5AC, a novel family of mucin proteins, composed of 2–27 cysteine-rich domains, presents in cartilaginous and bony fishes. Using in situ hybridization and transgenic reporter assays, we demonstrated that zebrafish muc5AC is specifically expressed in the support cells of neuromasts. Knockdown of muc5AC via antisense morpholino resulted in shorter cupulae in zebrafish lateral line. Additionally, we generated zebrafish muc5AC mutants using CRISPR/Cas9 and found that cupulae in muc5AC mutants were significantly shorter than that in wild-types, but the hair cell number in neuromasts was not changed obviously. Furthermore, muc5AC mutant zebrafish larvae displayed compromised sensitivity to vibration stimuli compared to wild-type larvae. This study provides the first evidence linking the muc5AC gene to cupula development and vibration detection in zebrafish. Our findings suggest that Mucin-5AC is likely a critical component of the cupula matrix, offering an important clue to the molecular composition of the lateral line cupula in fish. Full article

Parvalbumins are the main source of food allergies in fish meat, with each fish possessing multiple different parvalbumins. The naming convention of these allergens in terms of allergen codes (numbers) is species-specific. Allergen codes for parvalbumin isoallergens and allergen variants are based on sequence identities relative to the first parvalbumin allergen discovered in that particular species. This means that parvalbumins with similar allergen codes, such as catfish Pan h 1.0201 and redfish Seb m 1.0201, are not necessarily the most similar proteins, or encoded by the same gene. Here, we aim to elucidate the molecular basis of parvalbumins. We explain the complicated genetics of fish parvalbumins in an accessible manner for fish allergen researchers. Teleost or modern bony fish, which include most commercial fish species, have varying numbers of up to 22 parvalbumin genes. All have derived from ten parvalbumin genes in their common ancestor. We have named these ten genes “parvalbumin 1-to-10” (PVALB1-to-PVALB10), building on earlier nomenclature established for zebrafish. For duplicated genes, we use variant names such as, for example, “PVALB2A and PVALB2B”. As illustrative examples of our gene identification system, we systematically analyze all parvalbumin genes in two common allergy-inducing species in Japan: red seabream (Pagrus major) and chum salmon (Oncorhynchus keta). We also provide gene identifications for known parvalbumin allergens in various fish species. Full article

The increasing production of plastic products has raised concerns about environmental impacts related to microplastic formation, which harms ecosystems and human health. This systematic review aims to present the concentration of microplastics in commercially important bony fish and discuss the impacts on animal health and the possibility of these contaminants reaching the end consumer. The PICO methodology was used, and 517 articles were retrieved from four databases (PubMed, Embase, Web of Science, and Scopus); after selecting articles that complement the research objective, 70 articles were used to compose this review. According to the results, line-shaped microplastics, polypropylene, and polystyrene polymers were the most frequently identified in the articles. Additionally, the effects of microplastics on animal health, including false satiety and physical injuries, as well as risks to human health, such as epithelial inflammation, oxidative stress, and cell contamination, were discussed. Understanding the concentration of microplastics in commercially important bony fish is necessary for protecting human health and maintaining the health of marine ecosystems. It is necessary to adopt legislative measures for proper plastic disposal. Full article

The skin of bony fish is the first physical barrier and is responsible for maintaining the integrity of the fish. Lesions make the skin vulnerable to potential infection by pathogens present in the aquatic environment. In this way, wound repair has barely been studied in gilthead sea bream. Thus, this study investigated the modulation of peripheral neuro-endocrine and tissue repair markers at the transcriptional level in the skin of teleost fish subjected to mechanical damage above or below the lateral line (dorsal and ventral lesions, respectively). Samples were evaluated using RT-qPCR at 2-, 4-, and 20-days post-injury. Fish with a ventral lesion presented a trend of progressive increase in the expressions of corticotropin-releasing hormone (crh), pro-opiomelanocortin-A (pomca), proenkephalin-B (penkb), cholecystokinin (cck), oxytocin (oxt), angiotensinogen (agt), and (less pronounced) somatostatin-1B (sst1b). By contrast, fish with a dorsal lesion registered no significant increase or biological trend for the genes evaluated at the different sampling times. Collectively, the results show a rapid and more robust response of neuro-endocrine and tissue repair markers in the injuries below than above the lateral line, which could be attributable to their proximity to vital organs. Full article