Blocking and unblocking in a navigation task

Rodrigo, Chamizo, McLaren, & Mackintosh (1997) demonstrated the blocking effect in a navigational task using a swimming pool: rats initially trained to use three landmarks (ABC) to find an invisible platform learned less about a fourth landmark (X) added later than did rats trained from the outset with these four landmarks (ABCX). The aim of the experiment reported here was to demonstrate unblocking using a similar procedure as in the previous work. Three groups of rats were initially trained to find an invisible platfom in the presence of three landmarks: ABC for the Blocking and Unblocking groups and LMN for the Control group. Then, all animals were trained to find the platform in the presence of four landmarks, ABCX. In this second training, unlike animals in the Blocking group to which only a new landmark (X) was added in comparison to the first training, the animals in the Unblocking group also had a change in the platform position. In the Control group, both the four landmarks and the platform position were totally new at the beginning of this second training. As in Rodrigo et al. (1997) a blocking effect was found: rats in the Blocking group learned less with respect to the added landmark (X) than did animals in the Control group. However, rats in the Unblocking group learned about the added landmark (X) as well as did animals in the Control group. The results are interpreted as an unblocking effect due to a change in the platform position between the two phases of training, similarly to what is normal in classical conditioning experiments, in which a change in the conditions of reinforcement between the two training phases of a blocking design produce an attenuation or elimination of this effect. These results are explained within an error-correcting connectionist account of spatial navigation (McLaren, 2002)

Disruption of gut integrity and permeability contributes to enteritis in a fish‑parasite model: a story told from serum metabolomics

Background In the animal production sector, enteritis is responsible for serious economic losses, and intestinal parasitism is a major stress factor leading to malnutrition and lowered performance and animal production efficiency. The effect of enteric parasites on the gut function of teleost fish, which represent the most ancient bony vertebrates, is far from being understood. The intestinal myxozoan parasite Enteromyxum leei dwells between gut epithelial cells and causes severe enteritis in gilthead sea bream (Sparus aurata), anorexia, cachexia, growth impairment, reduced marketability and increased mortality. Methods This study aimed to outline the gut failure in this fish-parasite model using a multifaceted approach and to find and validate non-lethal serum markers of gut barrier dysfunction. Intestinal integrity was studied in parasitized and non-parasitized fish by immunohistochemistry with specific markers for cellular adhesion (E-cadherin) and tight junctions (Tjp1 and Cldn3) and by functional studies of permeability (oral administration of FITC-dextran) and electrophysiology (Ussing chambers). Serum samples from parasitized and non-parasitized fish were analyzed using non-targeted metabolomics and some significantly altered metabolites were selected to be validated using commercial kits. Results The immunodetection of Tjp1 and Cldn3 was significantly lower in the intestine of parasitized fish, while no strong differences were found in E-cadherin. Parasitized fish showed a significant increase in paracellular uptake measured by FITC-dextran detection in serum. Electrophysiology showed a decrease in transepithelial resistance in infected animals, which showed a diarrheic profile. Serum metabolomics revealed 3702 ions, from which the differential expression of 20 identified compounds significantly separated control from infected groups in multivariate analyses. Of these compounds, serum inosine (decreased) and creatine (increased) were identified as relevant and validated with commercial kits. Conclusions The results demonstrate the disruption of tight junctions and the loss of gut barrier function, a metabolomic profile of absorption dysfunction and anorexia, which further outline the pathophysiological effects of E. leei

Aceites esenciales de diversas especies de Artemisia

Se analizan por CCF y CGL los aceites esenciales de especies del género Artemisia: A. herba-alba Asso var. glabrescens Boiss. (A. valentina Lamk.) y A. caerulescens L. sp. gallica (Willd.) K. Person (A. gallica Willd.). El análisis comparativo de los resultados pone de manifiesto las diferencias más notorias entre ellas, siendo más acusadas desde un punto de vista cuantitativo. Son componentes mayoritarios de la primera el alcanfor y α-terpineol y en la segunda predominan el alcanfor y α-tuyona.Essential oils from different Artemisia species: A. herba-alba Asso var. glabrescens Boiss. (A. valentina Lamk.) and A. caerulescens L. sp. gallica (Willd,) K. Persson (A. gallica Willd.) were analysed by TLC' and GLC. A comparative study of the results obtained showed that the most important differences between them were those observed from a quantitative point of view. Camphor and a -terpineol were the main components in the first specie; in the second one were camphor and α -thujone

Aceites esenciales de diversas especies de Artemisia

Essential oils from different Artemisia species: A. herba-alba Asso var. glabrescens Boiss. (A. valentina Lamk.) and A. caerulescens L. sp. gallica (Willd.) K. Persson (A. gallica Willd.) were analysed by TLC' and GLC. A comparative study of the results obtained showed that the most important differences between them were those observed from a quantitative point of view. Camphor and α-terpineol were the main components in the first specie; in the second one were camphor and α-thujone.Se analizan por CCF y CGL los aceites esenciales de especies del género Artemisia: A. herba-alba Asso var. glabrescens Boiss. (A. valentina Lamk.) y A. caerulescens L. sp. gallica (Willd.) K. Person (A. gallica Willd.). El análisis comparativo de los resultados pone de manifiesto las diferencias más notorias entre ellas, siendo más acusadas desde un punto de vista cuantitativo. Son componentes mayoritarios de la primera el alcanfor y α-terpineol y en la segunda predominan el alcanfor y α-tuyona

An Enriched European Eel Transcriptome Sheds Light upon Host-Pathogen Interactions with Vibrio vulnificus

Infectious diseases are one of the principal bottlenecks for the European eel recovery. The aim of this study was to develop a new molecular tool to be used in host-pathogen interaction experiments in the eel. To this end, we first stimulated adult eels with different pathogen-associated molecular patterns (PAMPs), extracted RNA from the immune-related tissues and sequenced the transcriptome. We obtained more than 2 x 10(6) reads that were assembled and annotated into 45,067 new descriptions with a notable representation of novel transcripts related with pathogen recognition, signal transduction and the immune response. Then, we designed a DNA-microarray that was used to analyze the early immune response against Vibrio vulnificus, a septicemic pathogen that uses the gills as the portal of entry into the blood, as well as the role of the main toxin of this species (RtxA13) on this early interaction. The gill transcriptomic profiles obtained after bath infecting eels with the wild type strain or with a mutant deficient in rtxA13 were analyzed and compared. Results demonstrate that eels react rapidly and locally against the pathogen and that this immune-response is rtxA13-dependent as transcripts related with cell destruction were highly up-regulated only in the gills from eels infected with the wild-type strain. Furthermore, significant differences in the immune response against the wild type and the mutant strain also suggest that host survival after V. vulnificus infection could depend on an efficient local phagocytic activity. Finally, we also found evidence of the presence of an interbranchial lymphoid tissue in European eel gills although further experiments will be necessary to identify such tissue

Accurate consideration of metal losses at waveguide junctions using admittance and impedance integral equation formulations

[EN] At higher frequencies, metal loss effects in passive waveguide components become more pronounced and hazardous. In this paper, we propose two integral equation techniques, based on the generalized admittance and impedance matrices, for the accurate consideration of losses in the metal walls of waveguide junctions. Both techniques have been evaluated in terms of accuracy and numerical efficiency, and conclusions are drawn regarding the best properties of the admittance parameter formulation. Finally, combining such technique with a classical perturbative method for considering propagation losses, we have successfully predicted all loss effects in two real waveguide filters used for commercial applications.This work has been supported by research projects TIC2000-0591-C03-01 and TIC2000-0591-C03-03 and special action ESP2001-4547-PE.Taroncher Calduch, M.; Hueso, J.; Cogollos, S.; Gimeno. B.; Boria Esbert, VE.; Vidal Pantaleoni, A.; Esteban González, H.... (2005). Accurate consideration of metal losses at waveguide junctions using admittance and impedance integral equation formulations. Radio Science. 40(6):1-12. doi:10.1029/2004RS003225S11240

How do novel feed formulations affect growth performance, oxidative stress and immune response of atlantic salmon?

Trabajo presentado en la International Conference & Exposition Aquaculture Europe, celebrada en Funchal, Maderia (Portugal) del 04 al 07 de octubre de 2021.[Introduction]: The aquaculture industry continues to grow faster than any other sector of food production. The need to make aquaculture as sustainable and more environmentally conscious as possible is becoming clearer everyday (FAO, 2020). With this in mind, the replacement of fishmeal and fish oil in aquafeeds has been studied in Atlantic salmon (Salmo salar) (e.g., Bendiksen et al., 2011) with many products emerging as potential alternatives to conventional ones (e.g., Hodar et al., 2020). One of the main objectives of the EU project GAIN is to evaluate new ingredients that are already commercially available using different formulation concepts that consider all the fish nutritional needs. GAIN diets are based on circular economy principles and maximize resource efficiency, while contributing to zero waste in the agri-food value chain, being cost-effective feeds, and having good social acceptability. The present study aims to understand the actual effects of these novel feed formulations on growth performance, nutritional status, immunity and oxidative status.[Methods]: Quadruplicate groups of Atlantic salmon were fed ad libitum with three different diets. Two diets were developed to facilitate the eco-intensification of aquaculture through increased circularity and resource utilization (NOPAP - formula without processed animal protein - and PAP - formula with processed animal protein). The third diet was a commercial-like formulation that was used as a control. After a 96-day feeding trial, plasma samples were collected to evaluate humoral parameters (protease, anti-protease, bactericidal activity, and IgM). Liver and head kidney tissues (collected at day 45 and 96) were used for the simultaneous profiling by PCR array of a panel of 38 or 28 genes, respectively, as markers of growth performance, lipid and energy metabolism, and immune and antioxidant activities. Liver samples were also used to analyse lipid peroxidation. In addition, after 45 and 96 days, the lice count and fish welfare were also assessed by standard methods. The dorsal skin and foregut were collected at days 45 and 96 for mucosal mapping (mucous cell area, density, and barrier status).[Results]: Growth performance was adequate and comparable to commercial standards for the novel diets tested. Other parameters analysed, including those related to key performance indicators, intestinal and skin dorsal mucosal mapping, plasma innate immune defences, and lipid peroxidation in the liver did not significantly differ across diets. Regarding head kidney gene expression, at Day 45, 2 out of 28 genes in the array were differentially expressed (p<0.05). Gene expression of fish fed with novel feed formulations showed a pro-inflammatory profile evidenced by the up regulation of il-8, and a down regulation of il-10.At Day 96, the same genes continued to be differentially expressed, but gene clec1b (membrane protein) was also up-regulated. However, the rest of the analyses do not support this pro-inflammatory profile. A longer trial may bring light to some of the current results. In turn, the liver had a differential gene expression only at the second sampling point (Day96), where 4 out of 38 genes in the array were affected, including growth performance (igf2), lipid metabolism, elongases (elovl4), and energy metabolism (ucp2l and sirt1). These transcriptomic changes may be attributed to an initial response to the experimental diets. Cross-analysis of gene expression by time points and dietary treatment (two-way ANOVA) yielded only 2 out of 38 genes that had significantly different expression across treatments. The differentially expressed genes were related to growth performance (igf2) and lipid metabolism (elovl4).[Conclusions]: The novel feed formulations of the GAIN project for Atlantic Salmon seem to be viable options for the near future. In any case, all results are related to the formulation itself and cannot be attributed to a specific ingredient alteration. More studies are necessary to understand the cost-benefit of these new formulations and their market acceptability to optimize sustainability within the current/predictable European regulatory framework.This project was financed by the European Union’s Horizon 2020 research and innovation programme under grant agreement N° 773330 (GAIN), with additional support from Nord University (Norway) and SPAROS Lda (Portugal)

Modulation of gilthead sea bream gut microbiota by a bioactive egg white hydrolysate: Interactions between bacteria and host lipid metabolism

This study aimed to highlight the relationship between diet, animal performance and mucosal adherent gut microbiota (anterior intestine) in fish fed plant-based diets supplemented with an egg white hydrolysate (EWH) with antioxidant and antiobesogenic activity in obese rats. The feeding trial with juveniles of gilthead sea bream (Sparus aurata) lasted 8 weeks. Fish were fed near to visual satiety with a fish meal (FM)/fish oil (FO) based diet (CTRL) or a plant-based diet with/without EWH supplementation. Specific growth rate decreased gradually from 2.16% in CTRL fish to 1.88% in EWH fish due to a reduced feed intake, and a slight impairment of feed conversion ratio. Plant-based diets feeding triggered a hyperplasic inflammation of the anterior intestine regardless of EWH supplementation.This work was supported by the EU H2020 Research Innovation Program under the TNA Program (project AE150009) at IATS-CSIC Research Infrastructure within AQUAEXCEL2020 Project (652831). This output reflects only the author’s view and the European Union cannot be held responsible for any use that may be made of the information contained herein. Additional funding was obtained by a Spanish MICINN project (Bream-AquaINTECH and RTI2018–094128-B-I00). MCP was funded by a Ramón y Cajal Postdoctoral Research Fellowship [RYC2018-024049-I/AEI/10.13039/501100011033 cofunded by the European Social Fund (ESF) and ACOND/2020 Generalitat Valenciana].Peer reviewe