Browsing by Subject "teleosts"

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    Effect of Light–Dark Cycle on Skin Mucosal Immune Activities of Gilthead Seabream (Sparus aurata) and European Sea Bass (Dicentrarchus labrax)
    (MDPI, 2020) Ceballos-Francisco, Diana; Cuesta Peñafiel, Alberto; Esteban Abad, María de los Ángeles; Biología Celular e Histología
    Changes in di erent immune activities in the skin mucus of gilthead seabream (Sparus aurata L.) and European sea bass (Dicentrarchus labrax L.) specimens exposed to a constant light–dark photoperiod (12 h L:12 h D) were studied. Samples were collected at 08:00 (light on), 14:00, 20:00 (light o ), 02:00, and again at 08:00 to determine immunoglobulin M (IgM) levels, several enzymes related to the immune system, and bactericidal activity. IgM levels were higher during the day in seabream and reached a minimum value at 20:00, but it was hardly a ected in sea bass. No significant variations were recorded in the levels of protease and antiprotease. Peroxidase reached its maximum level in seabream at 02:00, the same time that it reached its minimum level in sea bass. Lysozyme showed little variation in seabream, but it was significantly lower at 14:00 than during the rest of the cycle in sea bass. Finally, di erent interspecific variations on bactericidal activity against Vibrio harveyi were recorded. The findings demonstrate that the immune parameters present in skin mucus of these important fish species are a ected by the light–dark cycle and that there are substantial interspecies di erences.
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    Phagocytosis in teleosts. Implications of the new cells involved
    (MDPI, 2015) Chaves-Pozo, Elena; Meseguer, José; Cuesta Peñafiel, Alberto; Esteban Abad, María de los Ángeles; Biología Celular e Histología
    Phagocytosis is the process by which cells engulf some solid particles to form internal vesicles known as phagosomes. Phagocytosis is in fact a specific form of endocytosis involving the vesicular interiorization of particles. Phagocytosis is essentially a defensive reaction against infection and invasion of the body by foreign substances and, in the immune system, phagocytosis is a major mechanism used to remove pathogens and/or cell debris. For these reasons, phagocytosis in vertebrates has been recognized as a critical component of the innate and adaptive immune responses to pathogens. Furthermore, more recent studies have revealed that phagocytosis is also crucial for tissue homeostasis and remodeling. Professional phagocytes in teleosts are monocyte/macrophages, granulocytes and dendritic cells. Nevertheless, in recent years phagocytic properties have also been attributed to teleost lymphocytes and thrombocytes. The possible implications of such cells on this important biological process, new factors affecting phagocytosis, evasion of phagocytosis or new forms of phagocytosis will be considered and discussed.