Search

In vitro cell culture systems serve as instrumental platforms for probing biological phenomena and elucidating intricate cellular mechanisms. These systems afford researchers the opportunity to scrutinize cellular responses within a regulated environment, thereby circumventing the ethical and logistical challenges associated with in vivo experimentation. Three-dimensional (3D) cell cultures have emerged as a viable alternative to mimic in vivo environments. Within this context, spheroids are recognized as one of the most straightforward and efficacious models, presenting a promising substitute for conventional monolayer cultures. The application of 3D cultures of fish cells remains limited, focusing mainly on physiological and morphological characterization studies. However, given the capacity of spheroids to emulate in vivo conditions, researchers are exploring diverse applications of these 3D cultures. These include eco-toxicology, immunology, drug screening, endocrinology, and metabolism studies, employing a variety of cell types such as fibroblasts, hepatocytes, embryonic cells, gonadal cells, gastrointestinal cells, and pituitary cells. This review provides a succinct overview, concentrating on the most frequently employed methods for generating fish cell spheroids and their applications to date. The aim is to compile and highlight the significant contributions of these methods to the field and their potential for future research. [ABSTRACT FROM AUTHOR]

Amid growing concerns about antibiotic resistance, innovative strategies are imperative in addressing bacterial infections in aquaculture. Quorum quenching (QQ), the enzymatic inhibition of quorum sensing (QS), has emerged as a promising solution. This study delves into the QQ capabilities of the probiotic strain Bacillus velezensis D-18 and its products, particularly in Vibrio anguillarum 507 communication and biofilm formation. Chromobacterium violaceum MK was used as a biomarker in this study, and the results confirmed that B. velezensis D-18 effectively inhibits QS. Further exploration into the QQ mechanism revealed the presence of lactonase activity by B. velezensis D-18 that degraded both long- and short-chain acyl homoserine lactones (AHLs). PCR analysis demonstrated the presence of a homologous lactonase-producing gene, ytnP, in the genome of B. velezensis D-18. The study evaluated the impact of B. velezensis D-18 on V. anguillarum 507 growth and biofilm formation. The probiotic not only controls the biofilm formation of V. anguillarum but also significantly restrains pathogen growth. Therefore, B. velezensis D-18 demonstrates substantial potential for preventing V. anguillarum diseases in aquaculture through its QQ capacity. The ability to disrupt bacterial communication and control biofilm formation positions B. velezensis D-18 as a promising eco-friendly alternative to conventional antibiotics in managing bacterial diseases in aquaculture. [ABSTRACT FROM AUTHOR]

Dietary supplementation with Omega-3 fatty acids seems to promote skeletal health. Therefore, their consumption at imbalanced or excessive levels has offered less beneficial or even prejudicial effects. Fish produced in aquaculture regimes are prone to develop abnormal skeletons. Although larval cultures are usually fed with diets supplemented with Omega-3 Long Chain Polyunsaturated fatty acids (LC-PUFAs), the lack of knowledge about the optimal requirements for fatty acids or about their impact on mechanisms that regulate skeletal development has impeded the design of diets that could improve bone formation during larval stages when the majority of skeletal anomalies appear. In this study, Argyrosomus regius larvae were fed different levels of Omega-3s (2.6% and 3.6% DW on diet) compared to a commercial diet. At 28 days after hatching (DAH), their transcriptomes were analyzed to study the modulation exerted in gene expression dynamics during larval development and identify impacted genes that can contribute to skeletal formation. Mainly, both levels of supplementation modulated bone-cell proliferation, the synthesis of bone components such as the extracellular matrix, and molecules involved in the interaction and signaling between bone components or in important cellular processes. The 2.6% level impacted several genes related to cartilage development, denoting a special impact on endochondral ossification, delaying this process. However, the 3.6% level seemed to accelerate this process by enhancing skeletal development. These results offered important insights into the impact of dietary Omega-3 LC-PUFAs on genes involved in the main molecular mechanism and cellular processes involved in skeletal development. [ABSTRACT FROM AUTHOR]

Flow cytometry (FC) is a straightforward, highly specific and sensitive procedure, which provides objective and quantitative recording of fluorescent signals from individual cells. FC has been used widely in the area of aquaculture research due mainly to the development of monoclonal antibodies (mabs). Phagocyte activity of head–kidney macrophages of several fish species, antibody production against specific antigens or detection of viruses inside immune cells are some of the several possible analysis approached by this assay. The aim of this work is to analyse and to compare kinetics of IgM-positive cells in the gill and spleen of sea bream juveniles after bath immunization against Photobacterium damselae subsp. piscicida (Phdp) using a direct staining method. Fish were immunized with three different inactivated vaccines prepared with 94/99 antigen and a commercial vaccine was used as a positive control. The effect on IgM-positive cells post-vaccination was compared among groups. Results show that the direct staining method with mabs is an effective and repeatable method for staining sea bream IgM-positive cells. [ABSTRACT FROM AUTHOR]

Hafnia alveiis a Gram negative bacterium that belongs to the familyEnterobacteriaceae. It is part of the intestinal flora of humans and animals, moreover it has been described from natural environments and foodstuffs. In human medicine is considered an opportunistic bacterium that causes different infections associated to underlying illnesses or predisposing factors as immunocompromised patients. The knowledge and literature about this bacterium in veterinary medicine is scarce, highlighting its importance in gastropods and bees, and it has also been described in poultry, mares, fish and ruminants producing various clinicopathologic signs. [ABSTRACT FROM PUBLISHER]

In this work, we evaluated the effect of the probioticEnterococcus gallinarumL-1 on the cellular immune system of four different fish species of great interest in aquaculture such as gilthead sea bream (Sparus aurata), European sea bass (Dicentrarchus labrax), meagre (Argyrosomus regius) and red porgy (Pagrus pagrus). Phagocytic activity, respiratory burst and peroxidase content of leucocytes were observed 30 minutes after incubation with the probioticE. gallinarumstrain L-1, alive or inactivated with heat shock or ultraviolet (UV) light at different concentrations of 107, 108and 109cfu mL−1(final concentration 106, 107and 108cfu mL−1).E. gallinarumproduced dose-dependent increments in respiratory burst in red porgy, sea bream and sea bass leucocytes. About 106and 107cfu mL−1of live and inactivated bacteria with no stimulation of the respiratory burst activity of sea bream and red porgy head kidney leucocytes was shown. The highest values of peroxidase content were observed in red porgy cells with stimulation indexes higher than 1 in each treatment. Statistical analysis revealed that differences were only significant in sea bream where UV light-inactivated bacteria denote statistically significant differences (P< 0.05) with respect to other treatments. Highest values of phagocytic activity were obtained in sea bream leucocytes incubated with live bacteria (26% ± 1.88), where significant differences (P< 0.05) with other species were detected. Our results suggest that thein vitroassays may be useful in optimising their effective dose and viability for the immunomodulatory effects of probiotic bacteria, althoughin vivostudies are necessary to confirm the immunomodulatory effect of this strain. [ABSTRACT FROM PUBLISHER]

The surface-associated proteins play a key role in bacterial physiology and pathogenesis, and are the major targets in the development of new vaccines. These proteins contribute to the adaptation of bacteria to different hosts and environments. To study differences at the genomic level, we first sequenced the whole genome of Streptococcus iniae from fish (IUSA-1 strain) and compared it to Streptococcus iniae from human (9117 strain), revealing a high similitude between both strains. To gain further insights into host- and environment-specific differences, we then studied proteins in silico and by High Performance Liquid Chromatography. This approach successfully identified 54 secreted and surface proteins, including several proteins involved in cell wall synthesis and transport of solutes, as well as proteins with yet unknown function. These proteins highlight as interesting targets for further investigation in the interaction between Streptococcus iniae and its environment. Results reported in this study have shown a first analysis about the predicted and experimental associated proteins of Streptococcus iniae isolated from two different hosts: human and fish.