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Previously, we identified and characterized the IgM and IgT classes in the Antarctic teleost Trematomus bernacchii, a species belonging to the Perciform suborder Notothenoidei. Herein we characterized the gene encoding the polymeric immunoglobulin receptor (pIgR) in the same species and compared it to pIgR of multiple teleost species belonging to five perciform suborders, including 11 Antarctic and one non-Antarctic (Cottoperca gobio) notothenioid species, the latter living in less cold periantarctic sea. Antarctic pIgR genes displayed particularly long introns marked by sites of transposable elements and transcription factors. Furthermore, analysis of T. bernacchii pIgR cDNA unveiled multiple amino acid substitutions unique to Antarctic species, all introducing adaptive features, including N-glycosylation sequons. Interestingly, C. gobio shared most features with the other perciforms rather than with the cold adapted relatives. T. bernacchii pIgR transcripts were predominantly expressed in mucosal tissues, as indicated by q-PCR and in situ hybridization analysis. These results suggest that in cold adapted species pIgR preserved its fundamental role in mucosal immune defense, although remarkable gene structure modifications occurred.

In jawed vertebrates, adaptive immune responses are enabled by T cells. Two lineages were characterized based on their T cell receptor (TcR) heterodimers, namely αβ or γδ peptide chains, which display an Ig domain-type sequence that is somatically rearranged. γδ T cells have been less extensively characterized than αβ and teleost fish, in particular, suffer from a severe scarcity of data. In this paper, we worked on the well-known model, the European sea bassDicentrarchus labrax,to broaden the understanding of teleost γδ-T cells. The T cell receptor chain (TR) γ transcript was expressed at a later developmental stage than TRβ, suggesting a layered appearance of fish immune cells, and the thymus displayed statistically-significant higher mRNA levels than any other organ or lymphoid tissue investigated. The polyclonal antibody developed against the TRγ allowed the localization of TRγ-expressing cells in lymphoid organs along the ontogeny. Cell positivity was investigated through flow cytometry and the highest percentage was found in peripheral blood leukocytes, followed by thymus, gut, gills, spleen and head kidney. Numerous TRγ-expressing cells were localized in the gut mucosa, and the immunogold labelling revealed ultrastructural features that are typical of T cells. At last, microalgae-based diet formulations significantly modulated the abundance of TRγ+cells in the posterior intestine, hinting at a putative involvement in nutritional immunity. From a comparative immunological perspective, our results contribute to the comprehension of the diversity and functionalities of γδ T cells during the development of a commercially relevant marine teleost model.

This article belongs to the Special Issue 3D Cell Culture Based on Marine Resources., Plocabulin is a novel microtubule-disrupting antitumor agent of marine origin that is currently undergoing phase II clinical trials. Plocabulin has potent antiproliferative and antiangiogenic actions in carcinoma cell lines and has antitumor activity in xenografted mice. Here, we used three-dimensional (3D) tumor organoids derived from three colorectal cancer (CRC) patients to study the effect of plocabulin in a personalized assay system that ensures dose dependence and high reproducibility. The cytotoxicity of plocabulin was an order of magnitude higher than that of the active irinotecan derivative SN38 (7-ethyl-10-hydroxy-camptothecin) in tumor organoids at different passages. Moreover, plocabulin maintained its strong cytotoxic activity in wash-out experiments, in which a short pulse treatment of tumor organoids was as efficient as continuous treatment. Our data show that plocabulin has a very potent cytotoxic action in CRC patient-derived tumor organoids, supporting ongoing clinical trials with plocabulin and the use of organoid assays to provide personalized validation of antitumor drugs., This study was supported by grants SAF2016-76377-R (AEI/FEDER, UE), SAF2017-90604-REDT (Nurcamein) and ISCIII-CIBERONC CB16/12/00273 (to A.M.) from the Spanish Ministry of Science, Innovation and Universities.