Percorrer por autor "Sanahuja, Ignasi"
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- Environmental salinity modifies mucus exudation and energy use in European Sea Bass JuvenilesPublication . Ordóñez-Grande, Borja; Guerreiro, Pedro M; Sanahuja, Ignasi; Fernández-Alacid, Laura; Ibarz, AntoniThe European sea bass (Dicentrarchus labrax) is a euryhaline marine teleost that can often be found in brackish and freshwater or even in hypersaline environments. Here, we exposed sea bass juveniles to sustained salinity challenges for 15 days, simulating one hypoosmotic (3‰), one isosmotic (12‰) and one hyperosmotic (50‰) environment, in addition to control (35‰). We analyzed parameters of skin mucus exudation and mucus biomarkers, as a minimally invasive tool, and plasma biomarkers. Additionally, Na+/K+ -ATPase activity was measured, as well as the gill mucous cell distribution, type and shape. The volume of exuded mucus increased significantly under all the salinity challenges, increasing by 130% at 50‰ condition. Significantly greater amounts of soluble protein (3.9 ± 0.6 mg at 50‰ vs. 1.1 ± 0.2 mg at 35‰, p < 0.05) and lactate (4.0 ± 1.0 µg at 50‰ vs. 1.2 ± 0.3 µg at 35‰, p < 0.05) were released, with clear energy expenditure. Gill ATPase activity was significantly higher at the extreme salinities, and the gill mucous cell distribution was rearranged, with more acid and neutral mucin mucous cells at 50‰. Skin mucus osmolality suggested an osmoregulatory function as an ion-trap layer in hypoosmotic conditions, retaining osmosis-related ions. Overall, when sea bass cope with different salinities, the hyperosmotic condition (50‰) demanded more energy than the extreme hypoosmotic condition.
- Evaluating the repetitive mucus extraction effects on mucus biomarkers, mucous cells, and the skin-barrier status in a marine fish modelPublication . Sanahuja, Ignasi; Guerreiro, Pedro; Girons, Albert; Fernandez-Alacid, Laura; Ibarz, AntoniAmong all the mucosal barriers, the skin and its surrounding mucus are possibly the main defensive tool against changes in the environment that can be harmful for fish. Due to the extraction of this mucus being less invasive, the study of its production and functions has attracted great interest in recent years. However, there are still many gaps concerning the sampling process as well as the possible alterations in skin integrity and mucus composition. In the current study, the effects of skin mucus extraction were determined by comparing the effects of a single extraction (single extraction group, SEG) with those of three successive extractions separated by 3 days (repetitive extractions group, REG). Intact skin histology without mucus extraction (oEG) and both plasma and skin mucus biomarkers and antibacterial capacities were also assessed. Regarding the skin histology and skin barrier properties, both the SEG and REG did not show differences in the intact skin. Interestingly, repetitive mucus extractions seemed to activate skin mucus turnover, significantly increasing the number of small-sized mucous cells (cell area< 100 mu m(2)) and reducing the number of large-sized mucous cells (cell area > 150 mu m(2)). Repetitive extractions significantly decreased the amounts of soluble protein and increased cortisol secretion. These metabolites remained unaltered in the plasma, indicating different responses in the plasma and mucus. Despite changes in the mucus biomarkers, antibacterial capacity against pathogenic bacteria (Pseudomonas anguilliseptica and Vibrio anguillarum) was maintained in both the plasma and mucus irrespective of the number of mucus extractions. Overall, the mucus sampling protocol had little effect on skin integrity and mucus antibacterial properties, only modifying the amounts of soluble protein exuded and stimulating mucous cell replacement. This protocol is a feasible and minimally invasive way of studying and monitoring fish health and welfare and can be used as an alternative or a complement to plasma analysis. This methodology can be transferred to farm culture conditions and be very useful for studying threatened species in order to preserve fish welfare.
- Modulation of pituitary response by dietary lipids and throughout a temperature fluctuation challenge in Gilthead Sea BreamPublication . Sánchez-Nuño, Sergio; Silva, Sandra; Guerreiro, Pedro M; Ordóñez-Grande, Borja; Sanahuja, Ignasi; Fernández-Alacid, Laura; Ibarz, AntoniLow temperatures provoke drastic reductions in gilthead sea bream (Sparus aurata) activity and nourishment, leading to growth arrest and a halt in production. However, scarce data exist concerning the implications of central core control during the cold season. The aim of this work was to study the effects of low temperature and recovery from such exposure on the pituitary activity of sea bream juveniles fed 18% or 14% dietary lipid. A controlled indoor trial was performed to simulate natural temperature fluctuation (22 ◦C to 14 ◦C to 22 ◦C). Meanwhile, we determined the regulatory role of the pituitary by analyzing the gene expression of some pituitary hormones and hormone receptors via qPCR, as well as plasma levels of thyroidal hormones. In response to higher dietary lipids, hormone pituitary expressions were up-regulated. Induced low temperatures and lower ingesta modulated pituitary function up-regulating GH and TSH and thyroid and glucocorticoid receptors. All these findings demonstrate the capacity of the pituitary to recognize both external conditions and to modulate its response accordingly. However, growth, peripheral tissues and metabolism were not linked or connected to pituitary function at low temperatures, which opens an interesting field of study to interpret the hypothalamus–pituitary–target axis during temperature fluctuations in fish.