UNASSIGNED: Red blood cells (RBCs), also known as erythrocytes, are underestimated in their role in the immune system. In mammals, erythrocytes undergo maturation that involves the loss of nuclei, resulting in limited transcription and protein synthesis capabilities. However, the nucleated nature of non-mammalian RBCs is challenging this conventional understanding of RBCs. Notably, in bony fishes, research indicates that RBCs are not only susceptible to pathogen attacks but express immune receptors and effector molecules. However, given the abundance of RBCs and their interaction with every physiological system, we postulate that they act in surveillance as sentinels, rapid responders, and messengers.
UNASSIGNED: We performed a series of in vitro experiments with Cyprinus carpio RBCs exposed to Aeromonas hydrophila, as well as in vivo laboratory infections using different concentrations of bacteria.
UNASSIGNED: qPCR revealed that RBCs express genes of several inflammatory cytokines. Using cyprinid-specific antibodies, we confirmed that RBCs secreted tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ). In contrast to these indirect immune mechanisms, we observed that RBCs produce reactive oxygen species and, through transmission electron and confocal microscopy, that RBCs can engulf particles. Finally, RBCs expressed and upregulated several putative toll-like receptors, including tlr4 and tlr9, in response to A. hydrophila infection in vivo.
UNASSIGNED: Overall, the RBC repertoire of pattern recognition receptors, their secretion of effector molecules, and their swift response make them immune sentinels capable of rapidly detecting and signaling the presence of foreign pathogens. By studying the interaction between a bacterium and erythrocytes, we provide novel insights into how the latter may contribute to overall innate and adaptive immune responses of teleost fishes.

Aquaculture supplies the world food market with a significant amount of valuable protein. Highly productive aquaculture fishes can be derived by utilizing genome-editing methods, and the main problem is to choose a target gene to obtain the desirable phenotype. This paper presents a review of the studies of genome editing for genes controlling body development, growth, pigmentation and sex determination in five key aquaculture Salmonidae and Cyprinidae species, such as rainbow trout (Onchorhynchus mykiss), Atlantic salmon (Salmo salar), common carp (Cyprinus carpio), goldfish (Carassius auratus), Gibel carp (Carassius gibelio) and the model fish zebrafish (Danio rerio). Among the genes studied, the most applicable for aquaculture are mstnba, pomc, and acvr2, the knockout of which leads to enhanced muscle growth; runx2b, mutants of which do not form bones in myoseptae; lepr, whose lack of function makes fish fast-growing; fads2, Δ6abc/5Mt, and Δ6bcMt, affecting the composition of fatty acids in fish meat; dnd mettl3, and wnt4a, mutants of which are sterile; and disease-susceptibility genes prmt7, gab3, gcJAM-A, and cxcr3.2. Schemes for obtaining common carp populations consisting of only large females are promising for use in aquaculture. The immobilized and uncolored zebrafish line is of interest for laboratory use.

The aim of the study was to compare the content of major components, selected elements and heavy metals in the fillet, spine and bones of a carp (Cyprinus carpio). Moreover, the extent to which a prepared portion of carp tissue (100 g of fillet and 10 g of carp spine or bones) met the requirements for analyzed elements in adults (women and men) and children was calculated. The proximate composition (total protein, total lipid, ash, moisture) and mineral content of the fish samples were determined. The nutrient composition presented fluctuations among the different tissues. Moisture was the main constituent in the fillet and in the spine with 77.8% and 56.0%, respectively, whereas in bones, the main ingredient was ash (36.2%). All carp tissues were good sources of protein, with 16.5%, 21.0% and 17.0% in spine, bones and fillet, respectively. The most abundant main elements were the potassium in the fillet (4005 mg kg-1) and calcium in the bones (116,463 mg kg-1). The most abundant trace elements were iron in fillet and zinc in bones and spine. Carp meat can be considered a safe foodstuff in terms of concentrations of Hg, Pb and Cd, as the levels of these contaminants were less than FAO and European Commission maximum guidelines.

The study examined the potential of Silymarin, a blend of bioactive flavonolignans extracted from the milk thistle Silybum marianum, to mitigate Deltamethrin-induced toxicity in the blood of Cyprinus carpio. Fish were exposed to Deltamethrin (0.66 μg/L), the plant extract, or a combination of both for a duration of thirty days. Various parameters, including serum biochemical markers, erythrocytic abnormalities, and genotoxicity endpoints, were assessed. Results indicated a significant (p < 0.05) increase in the levels of AST, ALT, ALP, blood urea nitrogen, creatinine, glucose, cholesterol, and TLC in the fish exposed to the pesticide. Conversely, total protein, TEC, and Hb showed a notable decrease. There was also a notable rise in micronuclei and erythrocytic abnormalities such as acanthocytes, microcytes, and notched cells. Under ultrastructural examination, phenotypic deformities like spherocytosis, discocytes, and clumped erythrocytes were observed. However, dietary supplementation of silymarin (1 g/kg) significantly restored the biochemical, genetic, and cellular parameters, resembling those of the control group. This suggests the potential of this plant extract in protecting the common carp, Cyprinus carpio, from Deltamethrin-induced damage by scavenging free radicals and reducing DNA oxidative stress.

BACKGROUND: Telocytes are modified interstitial cells that communicate with other types of cells, including stem cells. Stemness properties render them more susceptible to environmental conditions. The current morphological investigation examined the reactions of telocytes to salt stress in relation to stem cells and myoblasts. The common carp are subjected to salinity levels of 0.2, 6, and 10 ppt. The gill samples were preserved and prepared for TEM.
RESULTS: The present study observed that telocytes undergo morphological change and exhibit enhanced secretory activities in response to changes in salinity. TEM can identify typical telocytes. This research gives evidence for the communication of telocytes with stem cells, myoblasts, and skeletal muscles. Telocytes surround stem cells. Telopodes made planar contact with the cell membrane of the stem cell. Telocytes and their telopodes surrounded the skeletal myoblast. These findings show that telocytes may act as nurse cells for skeletal stem cells and myoblasts, which undergo fibrillogenesis. Not only telocytes undergo morphological alternations, but also skeletal muscles become hypertrophied, which receive telocyte secretory vesicles in intercellular compartments.
CONCLUSIONS: In conclusion, the activation of telocytes is what causes stress adaptation. They might act as important players in intercellular communication between cells. It is also possible that reciprocal interaction occurs between telocytes and other cells to adapt to changing environmental conditions.

Organophosphate insecticide spray poses potential threat of contamination of environmental components their accumulation in aquatic organisms. Although various physiological deficits associated with their exposure in fishes are documented, yet their retention in their edible muscle tissues has been poorly studied. In this context, the study was undertaken to ascertain the bioaccumulation of two organophosphate insecticide compounds (dimethoate and chlorpyrifos) in the muscles of juvenile Cyprinus carpio. The study could provide insight into the risks to human health associated with consuming contaminated fish flesh. The fishes exposed to various concentrations of dimethoate and chlorpyrifos in-vivo for 96 to ascertain the uptake and retention of these insecticides in the muscle. Results indicated that fish muscles accumulated the residues at all the concentrations with the recovery of 2.99% (0.032 ppm) of dimethoate exposed to LC50 concentrations. In contrast, the chlorpyrifos residues were found Below the Detection Level (BDL) in the fishes exposed to LC50 concentrations. The percentage bioaccumulation of dimethoate in fish muscle was 88.10%, and that of chlorpyrifos was BDL. The bio-concentration factor was dose-dependent and increased with increasing doses of both insecticides. The study invites attention to human health risk assessment in the regions where contaminated fish are consumed without scientific supervision.

A species introduced outside of its native range will likely encounter unusual abiotic and biotic conditions,and may exhibit phenotypic traits that may facilitate survival and persistance. Phenotypic plasticity drives non-native species\' development of adaptive traits in the new environment, increases their fitness, and as a result, contributes to invasion success. In this study, we examined inter and intraspecific phenotypic variation (body size and shape) for an invasive (Carassius gibelio) and introduced (Cyprinus carpio) cyprinid fish species (Teleostei: Cyprinidae) in the Düden Stream, Turkey, which is a small-scale river system. We hypothesized that interspecific phenotypic variation correlates with fish-specific variables and river site. We further hypothesized that these two species may exhibit similar phenotypic variation patterns between populations. The MANCOVA revealed that species-specific traits, river site, had significant effects on body shape variation and size along the stream. The differences in the shape of the head, the central portion of the body, and fins in both species most probably reflected differences in the swimming and feeding of the fish, possibly to avoid interspecies competition. The intraspecific phenotypic variation observed in both species may indicate rapid local adaptation, triggered by multiple founding event, or/and phenotypic plasticity.

As one of the most important environmental signals, photoperiod plays a crucial role in regulating the growth, metabolism, and survival of organisms. The photoperiod shifts with the transition of the seasons. The difference in photoperiod between summer and winter is the greatest under natural conditions. However, the effect of photoperiod on Huanghe carp (Cyprinus carpio haematopterus) was paid little attention. We investigated the impact of artificial manipulation of seasonal photoperiod on Huanghe carp by integrating growth performance, intestinal flora, and intestinal metabolome.
We conducted an 8-week culture experiment with summer photoperiod (14 h light:10 h dark, n = 60) as the control group and winter photoperiod (10 h light:14 h dark, n = 60) based on the natural laws.
Winter photoperiod provokes significant weight increases in Huanghe carp. The altered photoperiod contributed to a significant increase in triglyceride and low-density lipoprotein cholesterol levels and the gene expressions of lipid metabolism in the intestine of Huanghe carp. 16s rDNA sequencing revealed that winter photoperiod diminished intestinal flora diversity and altered the abundance. Specifically, the relative abundances of Fusobacteria and Acidobacteriota phyla were higher but Proteobacteria, Firmicutes, and Bacteroidetes phyla were reduced. Analogously, photoperiodic changes induced a significant reduction in the Pseudomonas, Vibrio, Ralstonia, Acinetobacter, and Pseudoalteromonas at the genus level. Additionally, metabolomics analysis showed more than 50% of differential metabolites were associated with phospholipids and inflammation. Microbiome and metabolome correlation analyses revealed that intestinal microbe mediated lipid metabolism alteration.
The winter photoperiod induced intestinal flora imbalance and lipid metabolism modification, ultimately affecting the growth of Huanghe carp. This study provides new insights into the effects of seasonal photoperiodic alteration on the well-being of fish.

Proanthocyanidins (Pros), a natural polyphenolic compound found in grape seed and other plants, have received significant attention as additives in animal feed. However, the specific mechanism by which Pros affect fish health remains unclear. Therefore, the aim of this study was to investigate the potential effects of dietary Pro on common carp by evaluating biochemical parameters and multi-omics analysis. The results showed that Pro supplementation improved antioxidant capacity and the contents of polyunsaturated fatty acids (n-3 and n-6) and several bioactive compounds. Transcriptomic analysis demonstrated that dietary Pro caused an upregulation of the sphingolipid catabolic process and the lysosome pathway, while simultaneously downregulating intestinal cholesterol absorption and the PPAR signaling pathway in the intestines. Compared to the normal control (NC) group, the Pro group exhibited higher diversity in intestinal microbiota and an increased relative abundance of Cetobacterium and Pirellula. Furthermore, the Pro group had a lower Firmicutes/Bacteroidetes ratio and a decreased relative abundance of potentially pathogenic bacteria. Collectively, dietary Pro improved antioxidant ability, muscle nutrients, and the diversity and composition of intestinal microbiota. The regulation of lipid metabolism and improvement in muscle nutrients were linked with changes in the intestinal microbiota.

During January 2013, a mining spill occurred in the Santa Maria mining region, releasing around 300,000 m3 of tailings on Los Remedios river, which was transported through the San Lorenzo river and finally to El Comedero (EC) dam. Twenty months later, we examined the concentrations of Hg and Se in the muscle, liver, gills, and guts of three fish species (Cyprinus carpio, Oreochromis aureus, Micropterus salmoides) captured in the EC dam to assess the performance of the cleaning operations. A high Se concentration in the liver of all species (carp, 1.2 ± 0.4; tilapia, 3.9 ± 2.1; bass, 3.5 ± 1.1 µg g-1 ww) was consistently observed, while this behavior was only found in the blue tilapia for Hg (0.15 ± 0.11 µg g-1 ww). Tilapia (benthic-detritivorous) exhibited the highest Se concentrations compared to the carp (omnivore) and the largemouth bass (piscivore). In contrast, the largemouth bass had the highest Hg levels in the muscle compared with the other fishes. Such differences could be related to the different metabolism and feeding habits among species. Compared to a tilapia study carried out three months after the mine spill during a mortality event, a decrease was evident in the liver for Se and Hg by 7.2 and 4.7 times, respectively. This reveals that cleaning operations were more efficient for Se and less for Hg, and that a prolonged period was required for the partial recovery of the element levels in fish from sites impacted by mining. Considering the Mexican consumption scenarios for each fish species, it could be concluded that there will be no non-cancer risk by exposure to Hg or Se.