1,721,045 research outputs found

    Survival of metazoan parasites in fish: Putting into context the protective immune responses of teleost fish

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    Defence mechanisms of fish can be divided into specific and non-specific that act in concert and are often interdependent. Most fish in both wild and cultured populations are vulnerable to metazoan parasites. Endoparasitic helminths include several species of digeneans, cestodes, nematodes, and acanthocephalans. Although they may occur in large numbers, helminth infections rarely result in fish mortality. Conversely, some ectoparasites cause mass mortality in farmed fish. Given the importance of fish innate immunity, this review addresses non-specific defence mechanisms of fish against metazoan parasites, with emphasis on granulocyte responses involving mast cells, neutrophils, macrophages, rodlet cells, and mucous cells. Metazoan parasites are important disease agents that affect wild and farmed fish and can induce high economic loss and, as pathogen organisms, deserve considerable attention. The paper will provide our light and transmission electron microscopy data on metazoan parasites-fish innate immune and neuroendocrine systems. Insights about the structure and functions of the cell types listed above and a brief account of the effects and harms of each metazoan taxon to specific fish apparati/organs will be presented

    Effects of experimental terbuthylazine exposure on the cells of Dicentrarchus labrax (L.)

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    The effects of acute exposure to the herbicide terbuthylazine (3.55, 5.01 and 7.08 mg l−1) on the cells of farmed European sea bass, Dicentrarchus labrax L., were investigated by means of light and electron microscopy. In gills of treated fish, the number of chloride cells (CCs) and rodlet cells (RCs) increased significantly within 24 h and 48 h, respectively; the intestine showed the largest increase in RCs linked to treatment and exposure time. In kidney, 24 h exposure induced a significant increase in RCs and the number and global area of macrophage aggregates (MAs).Treated fish displayed cellular and/or ultrastructural alterations in all the organs examined. In the gills necrosis, lamellar and cellular oedema, epithelial lifting, telangectasia, and fusion of secondary lamellae were encountered. The liver presented myelin-like figures, cytoplasmic rarefaction and acute cell swelling of hepatocytes. In both organs, the severity of damage was dose–dependent.In RCs of gills, the intestine and kidney of exposed sea bass, high cytoplasmic vacuolization, myelin-like figures, cristolysis and varying degrees of rodlet degeneration were observed. Extensive rodlet expulsion occurred in the gut lumen. Exposure to terbuthylazine also affected the renal tubular epithelial cells, which exhibited ‘blebs’. Damage to the intestinal epithelial cells was also observed.[...

    Perfluorooctanoic acid-induced cellular and subcellular alterations in fish hepatocytes

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    Liver perfluorooctanoic acid (PFOA) pathophysiology and related morphofunction disturbances were studied in common carp at the cellular and subcellular level and with box-counting fractal analysis of ultrathin sections to assess the effect of PFOA exposure on hepatocyte structure complexity and heterogeneity. Three experimental groups were investigated: unexposed; low exposure (200 ng L−1 PFOA); high exposure (2 mg L−1 PFOA). PFOA-exposed cells showed differences from controls at both tested concentrations, manifested mainly as cloudy swelling and reversible vacuolar degeneration. Subcellular modifications primarily involved mitochondria and secondarily endoplasmic reticulum, with evidence of increased subcellular turnover. The alterations were consistent with oxidative stress related pathophysiology. Fractal analysis discriminated exposed from unexposed fish and low from high PFOA exposure based on lacunarity and fractal dimension, respectively. The absence of irreversible organelle alterations and apoptosis/necrosis, along with the increase of cellular complexity, led to the conclusion that the patterns observed represented an adaptive recovery response
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