Biomarkers related to gas embolism: Gas score, pathology, and gene expression in a gas bubble disease model.

Fish exposed to water supersaturated with dissolved gas experience gas embolism similar to decompression sickness (DCS), known as gas bubble disease (GBD) in fish. GBD has been postulated as an alternative to traditional mammals' models on DCS. Gas embolism can cause mechanical and biochemical damage, generating pathophysiological responses. Increased expression of biomarkers of cell damage such as the heat shock protein (HSP) family, endothelin 1 (ET-1) or intercellular adhesion molecule 1 (ICAM-1) has been observed, being a possible target for further studies of gas embolism. The GBD model consisted of exposing fish to supersaturation in water with approximately 170% total dissolved gas (TDG) for 18 hours, producing severe gas embolism. This diagnosis was confirmed by a complete histopathological exam and the gas score method. HSP70 showed a statistically significant upregulation compared to the control in all the studied organs (p <0.02). Gills and heart showed upregulation of HSP90 with statistical significance (p = 0.015 and p = 0.02, respectively). In addition, HSP70 gene expression in gills was positively correlated with gas score (p = 0.033). These results suggest that gas embolism modify the expression of different biomarkers, with HSP70 being shown as a strong marker of this process. Furthermore, gas score is a useful tool to study the abundance of gas bubbles, although individual variability always remains present. These results support the validity of the GBD model in fish to study gas embolism in diseases such as DCS.

Morphological Assessment of Concomitant Lesions Detected in Goat Herds Naturally Infected with Paratuberculosis (Johne's Disease).

Paratuberculosis (PTB), caused by Mycobacterium avium subspecies paratuberculosis (MAP), causes significant financial losses in the ruminant industry. The aim of this study is to describe the concomitant pathological findings as well as PTB-induced lesions in 39 naturally infected goats (15 vaccinated and 24 non-vaccinated). All animals exhibited MAP-induced microscopic lesions affecting target organs, although only 62% of those were detected grossly. Mainly concomitant inflammatory pathologies were recognized affecting the hemolymphatic, respiratory and gastrointestinal systems. Non-vaccinated animals exhibited both moderate and marked granulomatous enteritis in contrast with vaccinated ones which presented mild intestinal affection. Our results demonstrate that non-vaccinated animals presented pneumonia in all age groups studied (from 12 up to >48 months old). A significantly higher prevalence of ileocecal valve PTB lesions was detected in non-vaccinated animals with pneumonic lesions (p = 0.027). Furthermore, a reduction of gastrointestinal non-PTB processes was described in vaccinated goats. In conclusion, a PTB infected goat herd can be affected by a wide range of concomitant pathologies, mostly inflammatory in origin. Anatomic pathology is of crucial importance for correct herd diagnosis and histopathology is an indispensable tool for lesion detection. Additionally, anti-MAP vaccination could have a beneficial effect on the reduction of respiratory and gastrointestinal non-PTB diseases.

Ciguatoxin-like toxicity distribution in flesh of amberjack (Seriola spp.) and dusky grouper (Epinephelus marginatus).

Ciguatoxins (CTXs) are marine neurotoxins that cause ciguatera poisoning (CP), mainly through the consumption of fish. The distribution of CTXs in fish is known to be unequal. Studies have shown that viscera accumulate more toxins than muscle, but little has been conducted on toxicity distribution in the flesh, which is the main edible part of fish, and the caudal muscle is also most commonly targeted for the monitoring of CTXs in the Canary Islands. At present, whether this sample is representative of the toxicity of an individual is undisclosed. This study aims to assess the distribution of CTXs in fish, considering different muscle samples, the liver, and gonads. To this end, tissues from four amberjacks (Seriola spp.) and four dusky groupers (Epinephelus marginatus), over 16.5 kg and captured in the Canary Islands, were analyzed by neuroblastoma-2a cell-based assay. Flesh samples were collected from the extraocular region (EM), head (HM), and different areas from the fillet (A-D). In the amberjack, the EM was the most toxic muscle (1.510 CTX1B Eq·g-1), followed by far for the caudal section of the fillet (D) (0.906 CTX1B Eq·g-1). In the dusky grouper flesh samples, D and EM showed the highest toxicity (0.279 and 0.273 CTX1B Eq·g-1). In both species, HM was one of the least toxic samples (0.421 and 0.166 CTX1B Eq·g-1). The liver stood out for its high CTX concentration (3.643 and 2.718 CTX1B Eq·g-1), as were the gonads (1.620 and 0.992 CTX1B Eq·g-1). According to these results, the caudal muscle next to the tail is a reliable part for use in determining the toxicity of fish flesh to guarantee its safe consumption. Additionally, the analysis of the liver and gonads could provide further information on doubtful specimens, and be used for CTX monitoring in areas with an unknown prevalence of ciguatera.

Ex vivo evaluation of adhesive strength and barrier effect of a novel treatment for esophagitis.

AIM: To investigate the mucoadhesive strength and barrier effect of Esophacare® (Atika Pharma SL, Las Palmas de Gran Canaria) in an ex vivo model of gastro-oesophageal reflux. METHODS: An ex vivo evaluation through the Falling Liquide Film Technique with porcine esophagi was performed, compared to a positive control (Ziverel®; Norgine, Amsterdam), after different washing periods with saline, acidified saline (pH 1.2) and acidified saline with pepsin (2000U/mL). RESULTS: The adhesive mean strength on the oesophageal mucosa of Esophacare was 94.7 (6.0)%, compared to 27.6 (19.1)% of the positive control (p<0.05). These results were homogeneous across the different washes and throughout the tissue. The area covered by 1mL of Esophacare, and its respective persistence after washing was also assessed, yielding a mean global persistence of 74.29 (19.7)% vs. 18.9 (12.3)% for the control (p<0.05). In addition, after 30min exposure to acidified saline with pepsin, Esophacare shows a protective effect on the oesophageal mucosa, detectable histologically: preserved integrity and structure of the apical layers was observed, as well as reduced permeability to the washing solution. CONCLUSIONS: Esophacare shows an adhesive strength close to 100%, irrespective of the washing solution applied or the oesophageal region studied. Histologically, it reduces the abrasive effects of the acidic solution on the oesophageal epithelium, reducing permeability to the washing solution. The results in this ex vivo model of gastro-oesophageal reflux disease (GERD) support its therapeutic potential.

Budd-Chiari-like pathology in dolphins.

Nearly two decades ago, pathologic examination results suggested that acoustic factors, such as mid-frequency active naval military sonar (MFAS) could be the cause of acute decompression-like sickness in stranded beaked whales. Acute systemic gas embolism in these whales was reported together with enigmatic cystic liver lesions (CLL), characterized by intrahepatic encapsulated gas-filled cysts, tentatively interpreted as "gas-bubble" lesions in various other cetacean species. Here we provide a pathologic reinterpretation of CLL in odontocetes. Among 1,200 cetaceans necropsied, CLL were only observed in four striped dolphins (Stenella coeruleoalba), with a low prevalence (2%, N = 179). Together, our data strongly suggest that CLL are the result of the combination of a pre-existing or concomitant hepatic vascular disorder superimposed and exacerbated by gas bubbles, and clearly differ from acute systemic gas embolism in stranded beaked whales that is linked to MFAS. Budd-Chiari-like syndrome in dolphins is hypothesized based on the present pathologic findings. Nonetheless, further researched is warranted to determine precise etiopathogenesis(es) and contributing factors for CLL in cetaceans.

Establishment of a fish model to study gas-bubble lesions.

Decompression sickness (DCS) is a clinical syndrome caused by the formation of systemic intravascular and extravascular gas bubbles. The presence of these bubbles in blood vessels is known as gas embolism. DCS has been described in humans and animals such as sea turtles and cetaceans. To delve deeper into DCS, experimental models in terrestrial mammals subjected to compression/decompression in a hyperbaric chamber have been used. Fish can suffer from gas bubble disease (GBD), characterized by the formation of intravascular and extravascular systemic gas bubbles, similarly to that observed in DCS. Given these similarities and the fact that fish develop this disease naturally in supersaturated water, they could be used as an alternative experimental model for the study of the pathophysiological aspect of gas bubbles. The objective of this study was to obtain a reproducible model for GBD in fish by an engineering system and a complete pathological study, validating this model for the study of the physiopathology of gas related lesions in DCS. A massive and severe GBD was achieved by exposing the fish for 18 h to TDG values of 162-163%, characterized by the presence of severe hemorrhages and the visualization of massive quantities of macroscopic and microscopic gas bubbles, systemically distributed, circulating through different large vessels of experimental fish. These pathological findings were the same as those described in small mammals for the study of explosive DCS by hyperbaric chamber, validating the translational usefulness of this first fish model to study the gas-bubbles lesions associated to DCS from a pathological standpoint.

Ciguatoxin Detection in Flesh and Liver of Relevant Fish Species from the Canary Islands.

The Canary Islands are a ciguatoxin (CTX) hotspot with an established official monitoring for the detection of CTX in fish flesh from the authorised points of first sale. Fish caught by recreational fishermen are not officially tested and the consumption of toxic viscera or flesh could lead to ciguatera poisoning (CP). The objectives of this study were to determine the presence of CTX-like toxicity in relevant species from this archipelago, compare CTX levels in liver and flesh and examine possible factors involved in their toxicity. Sixty amberjack (Seriola spp.), 27 dusky grouper (Epinephelus marginatus), 11 black moray eels (Muraena helena) and 11 common two-banded seabream (Diplodus vulgaris) were analysed by cell-based assay (CBA) and Caribbean ciguatoxin-1 (C-CTX1) was detected by liquid chromatography mass spectrometry (LC-MS/MS) in all these species. Most of the liver displayed higher CTX levels than flesh and even individuals without detectable CTX in flesh exhibited hepatic toxicity. Black moray eels stand out for the large difference between CTX concentration in both tissues. None of the specimens with non-toxic liver showed toxicity in flesh. This is the first evidence of the presence of C-CTX1 in the common two-banded seabream and the first report of toxicity comparison between liver and muscle from relevant fish species captured in the Canary Islands.

Initial Conditioning of Used Cigarette Filters for Their Recycling as Acoustical Absorber Materials.

Used cigarette butts represent a major and problematic form of waste, due to their abundance, toxicity, and durability. Moreover, the few proposals for their recycling are clearly insufficient, and new ones are welcome. For a new proposal regarding the reuse of used cigarette butts as acoustical absorbers in building construction, previous conditioning of the used butts is performed. This conditioning includes the elimination of moisture and toxic products accumulated in the filter of the cigarettes. Thus, in this work, the moisture content effect in acoustical absorption was analyzed, and a proposal for elimination is made. Moreover, a chemical cleaning procedure is proposed, and its influence on the acoustical behavior of the samples was also analyzed.

Intravenous metoprolol during ongoing STEMI ameliorates markers of ischemic injury: a METOCARD-CNIC trial electrocardiographic study.

Besides its protective effect against neutrophil-mediated injury at reperfusion, intravenous (IV) metoprolol was recently shown to reduce the progression of ischemic injury in a pig model of ST-segment elevation myocardial infarction (STEMI). Here, we tested the hypothesis that IV metoprolol administration in humans with ongoing STEMI blunts the time­dependent progression of ischemic injury assessed by serial electrocardiogram (ECG) evaluations before reperfusion. The METOCARD-CNIC trial randomized 270 anterior STEMI patients to IV metoprolol or control before reperfusion by percutaneous coronary intervention (PCI). In 139 patients (69 IV metoprolol, 70 controls), two ECGs were available (ECG-1 before randomization, ECG-2 pre-PCI). Between-group ECG differences were analyzed using univariate and multivariate regression models. No significant between-group differences were observed on ECG-1. On ECG-2, patients who received IV metoprolol had a narrower QRS than those in the control group (84 ms vs. 90 ms, p = 0.029), a lower prevalence of QRS distortion (10% vs. 26%, p = 0.017), and a lower sum of anterior and total ST-segment elevation (10.1 mm vs. 13.6 mm, p = 0.014 and 10.4 mm vs. 14.0 mm, p = 0.015, respectively). Adjusted analysis revealed similar results. Significant associations were observed between ECG-2 variables and cardiac magnetic resonance imaging measurements (extent of myocardial edema, infarct size, microvascular obstruction, and left-ventricular ejection fraction) after STEMI. In summary, IV metoprolol administration before reperfusion ameliorates ECG markers of myocardial ischemia in anterior STEMI patients. These data confirm that IV metoprolol is able to reduce ischemic injury and highlight the ability of ECG analysis to provide relevant real-time information on the effect of cardioprotective therapies before reperfusion.

A Study on the Pathological Effects of Trypanorhyncha Cestodes in Dusky Groupers Epinephelus marginatus from the Canary Islands.

Trypanorhyncha are cestodes commonly infecting marine fish. Numerous studies have detailed the biology of Trypanorhyncha species, but information on the pathological changes produced by these parasites is limited. Dusky groupers are keystone species necessary for the preservation of several marine ecosystems. Considering their vulnerable state of conservation and the efforts being made to culture them, identification of the effects caused by Trypanorhyncha is vital. Here, we aimed to determine the prevalence and pathological changes produced by Trypanorhyncha in dusky groupers from the Canary Islands. The prevalence of trypanorhynch plerocerci was 96%. Grossly, in the abdominal cavity, there were numerous larvae-filled cysts and nodules. These were embedded in abundant fibrosis, producing visceral adhesions. Histologically, affecting the peritoneum, stomach, and intestine there were numerous degenerated encysted plerocerci and extensive deposition of mature connective tissue. These findings indicate that Trypanorhyncha is highly prevalent in adult dusky groupers from the Canary Islands, producing a progressive and chronic response. Furthermore, fish immune system appears to attempt to eliminate the parasites through fibrous encapsulation. Nonetheless, extensive fibrosis may have a detrimental impact on fish health when adjacent cells or tissues are compressed and their functions impaired.

Decompressive Pathology in Cetaceans Based on an Experimental Pathological Model.

Decompression sickness (DCS) is a widely known clinical syndrome in human medicine, mainly in divers, related to the formation of intravascular and extravascular gas bubbles. Gas embolism and decompression-like sickness have also been described in wild animals, such as cetaceans. It was hypothesized that adaptations to the marine environment protected them from DCS, but in 2003, decompression-like sickness was described for the first time in beaked whales, challenging this dogma. Since then, several episodes of mass strandings of beaked whales coincidental in time and space with naval maneuvers have been recorded and diagnosed with DCS. The diagnosis of human DCS is based on the presence of clinical symptoms and the detection of gas embolism by ultrasound, but in cetaceans, the diagnosis is limited to forensic investigations. For this reason, it is necessary to resort to experimental animal models to support the pathological diagnosis of DCS in cetaceans. The objective of this study is to validate the pathological results of cetaceans through an experimental rabbit model wherein a complete and detailed histopathological analysis was performed. Gross and histopathological results were very similar in the experimental animal model compared to stranded cetaceans with DCS, with the presence of gas embolism systemically distributed as well as emphysema and hemorrhages as primary lesions in different organs. The experimental data reinforces the pathological findings found in cetaceans with DCS as well as the hypothesis that individuality plays an essential role in DCS, as it has previously been proposed in animal models and human diving medicine.

Lipids of lung and lung fat emboli of the toothed whales (Odontoceti).

Lipids are biomolecules present in all living organisms that, apart from their physiological functions, can be involved in different pathologies. One of these pathologies is fat embolism, which has been described histologically in the lung of cetaceans in association with ship strikes and with gas and fat embolic syndrome. To assess pathological lung lipid composition, previous knowledge of healthy lung tissue lipid composition is essential; however, these studies are extremely scarce in cetaceans. In the present study we aimed first, to characterize the lipids ordinarily present in the lung tissue of seven cetacean species; and second, to better understand the etiopathogenesis of fat embolism by comparing the lipid composition of lungs positive for fat emboli, and those negative for emboli in Physeter macrocephalus and Ziphius cavirostris (two species in which fat emboli have been described). Results showed that lipid content and lipid classes did not differ among species or diving profiles. In contrast, fatty acid composition was significantly different between species, with C16:0 and C18:1ω9 explaining most of the differences. This baseline knowledge of healthy lung tissue lipid composition will be extremely useful in future studies assessing lung pathologies involving lipids. Concerning fat embolism, non-significant differences could be established between lipid content, lipid classes, and fatty acid composition. However, an unidentified peak was only found in the chromatogram for the two struck whales and merits further investigation.

An end to the controversy over the microscopic detection and effects of pristine microplastics in fish organs.

The aquatic environment and the associated fish assemblages are being exposed to an increasing amount of microplastics. Despite the high number of publications on the presence of microplastics in fish, little is known about their uptake, translocation and accumulation within fish organs. Experimental studies on the detection and effects of pristine microplastics in fish have shown controversial and ambiguous results, respectively. Here, we conducted two experiments to detect and assess the impacts of dietary exposure of Danio rerio to different types of pristine microplastics. Our results show that D. rerio recognizes plastic particles as inedible materials but ingests them when mixed with food or fish oil. Accidental ingestion occurs in fish exposed to relatively small (1-5 µm) microplastic particles without associated food or fish oil. Additionally, D. rerio effectively eliminated pristine microplastics 24 h after ingestion; however, retention time was associated with increasing particle size and the intake of additional meals. Clinical signs, such as anorexia and lethargy, are present in fish fed relatively large microplastics (120-220 µm). The ingestion of microplastics does not induce any histopathological changes. To the best of our knowledge, we are able, for the first time, to fully demonstrate the uptake and translocation of plastic microbeads using confocal microscopy. Our results question the findings of previous studies on the detection and effects of pristine microplastics in fish and state that inaccurate interpretations of the histological findings regarding microplastics in fish organs is a prevalent flaw in the current scientific literature.

Tolerance and dose-response assessment of subchronic dietary ethoxyquin exposure in Atlantic salmon (Salmo salar L.).

Ethoxyquin (EQ; 6-Ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline) has been used as an antioxidant in feed components for pets, livestock and aquaculture. However, possible risks of EQ used in aquafeed for fish health have not yet been characterized. The present study investigated the toxicity and dose-response of subchronic dietary EQ exposure at doses ranging from 41 to 9666 mg EQ/kg feed in Atlantic salmon (Salmo salar L.). Feed at concentrations higher than 1173 mg EQ/kg were rejected by the fish, resulting in reduced feed intake and growth performance. No mortality was observed in fish exposed to any of the doses. A multi-omic screening of metabolome and proteome in salmon liver indicated an effect of dietary EQ on bioenergetics pathways and hepatic redox homeostasis in fish fed concentrations above 119 mg EQ/kg feed. Increased energy expenditure associated with an upregulation of hepatic fatty acid ß-oxidation and induction and carbohydrate catabolic pathways resulted in a dose-dependent depletion of intracytoplasmic lipid vacuoles in liver histological sections, decreasing whole body lipid levels and altered purine/pyrimidine metabolism. Increased GSH and TBARS in the liver indicated a state of oxidative stress, which was associated with activation of the NRF2-mediated oxidative stress response and glutathione-mediated detoxification processes. However, no oxidative DNA damage was observed. As manifestation of altered energy metabolism, the depletion of liver intracytoplasmic lipid vacuoles was considered the critical endpoint for benchmark dose assessment, and a BMDL10 of 243 mg EQ/kg feed was derived as a safe upper limit of EQ exposure in Atlantic salmon.

Increased parasite resistance of greater amberjack (Seriola dumerili Risso 1810) juveniles fed a cMOS supplemented diet is associated with upregulation of a discrete set of immune genes in mucosal tissues.

The main objective of this study was to determine the effect of two forms of mannan oligosaccharides (MOS: Bio-Mos® and cMOS: Actigen®, Alltech Inc, USA) and their combination on greater amberjack (Seriola dumerili) growth performance and feed efficiency, immune parameters and resistance against ectoparasite (Neobenedenia girellae) infection. Fish were fed for 90 days with 5 g kg-1 MOS, 2 g kg-1 cMOS or a combination of both prebiotics, in a Seriola commercial base diet (Skretting, Norway). At the end of the feeding period, no differences were found in growth performance or feed efficiency. Inclusion of MOS also had no effect on lysozyme activity in skin mucus and serum, but the supplementation of diets with cMOS induced a significant increase of serum bactericidal activity. Dietary cMOS also reduced significantly greater amberjack skin parasite levels, parasite total length and the number of parasites detected per unit of fish surface following a cohabitation challenge with N. girellae, whereas no effect of MOS was detected on these parameters. Of 17 immune genes studied cMOS dietary inclusion up-regulated hepcidin, defensin, Mx protein, interferon-γ (IFNγ), mucin-2 (MUC-2), interleukin-1ß (IL-1B), IL-10 and immunoglobulin-T (IgT) gene expression in gills and/or skin. MOS supplementation had a larger impact on spleen and head kidney gene expression, where piscidin, defensin, iNOS, Mx protein, interferons, IL-1ß, IL-10, IL-17 and IL-22 were all upregulated. In posterior gut dietary MOS and cMOS both induced IL-10, IgM and IgT, but with MOS also increasing piscidin, MUC-2, and IL-1ß whilst cMOS induced hepcidin, defensin and IFNγ. In general, the combination of MOS and cMOS resulted in fewer or lower increases in all tissues, possibly due to an overstimulation effect. The utilization of cMOS at the dose used here has clear benefits on parasite resistance in greater amberjack, linked to upregulation of a discrete set of immune genes in mucosal tissues.

QRS distortion in pre-reperfusion electrocardiogram is a bedside predictor of large myocardium at risk and infarct size (a METOCARD-CNIC trial substudy).

BACKGROUND: QRS distortion is an electrocardiographic (ECG) sign of severe ongoing ischemia in the setting of ST-segment elevation acute myocardial infarction (STEMI). We sought to evaluate the association between the degree of QRS distortion and myocardium at risk and final infarct size, measured by cardiac magnetic resonance (CMR). METHODS: A total of 174 patients with a first anterior STEMI reperfused by primary angioplasty were prospectively recruited. Pre-reperfusion ECG was used to divide the study population into three groups according to the absence of QRS distortion (D0) or its presence in a single lead (D1) or in 2 or more contiguous leads (D2+). Myocardium at risk and infarct size were determined by CMR one week after STEMI. Multiple regression analysis was used to study the association of QRS distortion with myocardium at risk and infarct size, with adjustment for relevant clinical and ECG variables. RESULTS: 101 patients (58%) were in group D0, 30 (17%) in group D1, and 43 (25%) in group D2+. Compared with group D0, presence of QRS distortion (groups D2+ and D1) was associated with a significantly adjusted larger extent of myocardium at risk (group D2+: absolute increase 10.4%, 95% CI 6.1-14.8%, p<0.001; group D1: absolute increase 3.3%, 95% CI 1.3-7.9%, p=0.157) and larger infarct size (group D2+: absolute increase 10.1%, 95% CI 5.5-14.7%, p<0.001; group D1: absolute increase 4.9%, 95% CI 0.08-9.8%, p=0.046). CONCLUSIONS: Distortion in the terminal portion of the QRS complex on pre-reperfusion ECG in two or more leads is independently associated with larger myocardium at risk and infarct size in the setting of primary angioplasty-reperfused anterior STEMI. QRS distortion in only one lead is independently associated with larger infarct size in this setting. Our findings suggest that QRS distortion analysis could be included in risk-stratification of patients presenting with anterior STEMI.

Dietary Mannan Oligosaccharides: Counteracting the Side Effects of Soybean Meal Oil Inclusion on European Sea Bass (Dicentrarchus labrax) Gut Health and Skin Mucosa Mucus Production?

The main objective of this study was to assess the effects of 4 g kg(-1) dietary mannan oligosaccharides (MOS) inclusion in soybean oil (SBO)- and fish oil (FO)-based diets on the gut health and skin mucosa mucus production of European sea bass juveniles after 8 weeks of feeding. Dietary MOS, regardless of the oil source, promoted growth. The intestinal somatic index was not affected, however dietary SBO reduced the intestinal fold length, while dietary MOS increased it. The dietary oil source fed produced changes on the posterior intestine fatty acid profiles irrespective of MOS dietary supplementation. SBO down-regulated the gene expression of TCRß, COX2, IL-1ß, TNFα, IL-8, IL-6, IL-10, TGFß, and Ig and up-regulated MHCII. MOS supplementation up-regulated the expression of MHCI, CD4, COX2, TNFα, and Ig when included in FO-based diets. However, there was a minor up-regulating effect on these genes when MOS was supplemented in the SBO-based diet. Both dietary oil sources and MOS affected mean mucous cell areas within the posterior gut, however the addition of MOS to a SBO diet increased the mucous cell size over the values shown in FO fed fish. Dietary SBO also trends to reduce mucous cell density in the anterior gut relative to FO, suggesting a lower overall mucosal secretion. There are no effects of dietary oil or MOS in the skin mucosal patterns. Complete replacement of FO by SBO, modified the gut fatty acid profile, altered posterior gut-associated immune system (GALT)-related gene expression and gut mucous cells patterns, induced shorter intestinal folds and tended to reduce European sea bass growth. However, when combined with MOS, the harmful effects of SBO appear to be partially balanced by moderating the down-regulation of certain GALT-related genes involved in the functioning of gut mucous barrier and increasing posterior gut mucous cell diffusion rates, thus helping to preserve immune homeostasis. This denotes the importance of a balanced dietary n-3/n-6 ratio for an appropriate GALT-immune response against MOS in European sea bass juveniles.

Dietary vegetable oils: effects on the expression of immune-related genes in Senegalese sole (Solea senegalensis) intestine.

The decreased availability of fish oil, traditionally used as oil source in marine aquafeeds, has lead to the search for alternatives oils. Vegetable oils (VO) are being extensively used as lipid sources in marine fish diets, inducing an imbalance on certain dietary fatty acids. Alteration on the dietary ratio of w-6/w-3 has been described to have detrimental effects on fish immunity. Senegalese sole has high susceptibility to stress and diseases, and little is known on the effects of dietary VO on its immunity. In this study, Senegalese sole juveniles were fed diets (56% crude protein, 12% crude lipid) containing linseed (100LO), soybean (100SO) or fish (100FO) oils as unique oil source. Growth, cortisol and intestinal fatty acid composition were determined after 90 days. Moreover, at the final of the experiment a stress test (5 min of net chasing) was carried out. To evaluate the effect of diets and stress on intestine immunology, expression profiles of a set of 53 immune-related genes using RT-qPCR was also performed. The use of VO did not induced changes in fish growth, but affected fatty acid profile of intestine and expression of immune-related genes. The use of SO (rich in n-6 fatty acids) induced an over-expression of those genes related to complement pathway, recognizing pathogen associated to molecular patterns, defensive response against bacteria, defensive response against viruses, antigen differentiation, cytokines and their receptors. This general over-expression could indicate an activation of inflammatory processes in fish gut. When a stress was applied, a decrease of mRNA levels of different immune-related genes with respect to the unstressed control could be observed in fish fed 100FO. However, fish fed 100LO, with a higher ALA/LA ratio, seemed to ameliorate the effects of combined effects of FO substitution plus stressful situation whereas fish fed 100SO did not show this type of response.