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In response to sustainability concerns related to the origin of raw materials, aquaculture has emphasized the use of additives and enhancers to improve the intestinal absorption of proteins and amino acids. However, the tools available to have a good proxy for potential intestinal absorption and to expose positive or negative effects are scarce. The present study had a two-fold objective: we first aimed to characterize electrogenic essential amino acid transport in the intestine of the gilthead seabream ex-vivo. We also aimed to understand if dietary lysophospholipids (LPLs) had positive or detrimental effects when incorporated into commercial diets in gilthead seabream (Sparus aurata) juveniles. The ex-vivo characterization in Ussing chambers showed a region-dependent electrogenic amino acid transport in the sea bream intestine, being maxima in the mid intestine and with a strong luminal sodium- and pH-dependence. In vivo, the animals were divided into two groups: one was fed a control diet (10 % fishmeal inclusion), whereas the other group was fed with the control diet supplemented with 0.1 % LPL in coated form. The LPL-inclusion was without effects on fish growth in a short-term feeding trial, although there was a significant improvement of hepatosomatic and viscerosomatic indices. Interestingly, the intestine of fish fed the aquafeed with a 0.1 % LPL supplementation increased paracellular permeability as measured in the anterior intestine and enhanced electrogenic amino acid transport in the mid intestine. Our results strongly suggest that the full potential of LPL-inclusion benefits could be explored in sustainable diets, nearly devoid of fishmeal and/or in fish subjected to environmental stress.

Objetivo: Un procedimiento para la gestión integrada de riesgos en la Universidad de las Ciencias Informáticas, La Habana, Cuba, como parte del fortalecimiento del sistema de control interno. Métodos: analítico-sintético, enfoque de sistema y estadística descriptiva. Principales resultados: el procedimiento se distingue por la forma de identificación, análisis y cuantificación de los riesgos que pueden ocurrir en cada uno de los procesos y sus actividades, y que impactan negativamente en el cumplimiento de los objetivos, la protección de los recursos y el cumplimiento del marco legal y regulatorio, para poder alcanzar los objetivos estratégicos y de trabajo. Se distingue también la determinación de los objetivos de control y su plan de prevención. Conclusiones: se muestran los resultados de la aplicación parcial del procedimiento en la Dirección de Control Interno del centro; se identificaron 15 riesgos y 48 causas asociadas a estos. Del análisis, los riesgos determinados fueron: cuatro moderados, siete bajos y dos triviales, de los cuales se establecieron seis riesgos relevantes, a los que se les realizó un análisis integrado para determinar cinco objetivos de control y 12 acciones.

Overexpression of asip1 in transgenic zebrafish disrupts dorsoventral pigment pattern in addition to increasing food intake levels and linear growth. A higher feed intake is unnecessary in transgenic fish to enable larger and heavier growth. A plausible explanation may rely on the enhanced feeding efficiency mediated by improved nutrient absorption in transgenic animals. To test this hypothesis, wide scope transcriptomic techniques were used to elucidate the potential pathways involved in the enhanced nutrient absorption and intestinal epithelium permeability/integrity. In addition, the electrogenic capacity for amino acid transport was analysed. Transcriptomic analysis reveal that amino acid, monocarboxylates, ionic and vitamin transmembrane transporters were substantially modified. Enrichment analysis also revealed an inhibition of intestinal lipid metabolism and down-regulation of KEGG pathways related to membrane integrity suggesting augmented intestinal laxity that may enhance paracellular transport. Electrophysiological experiments carried out in Ussing chambers show that asip1 overexpression decrease membraned tissue resistance (Rt), indicating a modification of the intestinal barrier function in ASIP1 transgenic animals. Similarly, paracellular permeability was higher in transgenic zebrafish. Both the decrease in Rt and the increase in permeability point to an ASIP1-dependent decrease in the tissue barrier function. Electrogenic amino acid transport was also enhanced in transgenic animals providing strong indication that ASIP1 fish can extract more amino acids from their diet at similar feeding levels. Both transcriptomic and electrophysiological results suggest that asip1-overexpressing zebrafish display improved nutrient absorption and by extension a higher feed efficiency which explains enhanced growth in the absence of augmented food intake. The enhanced growth of ASIP1 zebrafish potentially mediated by improved nutrient uptake and feed efficiency suggests that the melanocortin system, specifically asip1 overexpression, is a potential target for the development of genetically engineered fish displaying improved performance and no differential lipid accumulation.

The aim of this work was to evaluate the effects on growth performance, intermediary metabolism and welfare of the inclusion of two commercial microalgae-based ingredients called LB-ChromaBream (LB-CB) and LB-ChromaBream-plus (LB-CBplus) in the diet of gilthead seabream (Sparus aurata) close to commercial size. For this purpose, fish of ~182 g of initial body mass were fed to satiety (ad libitum) for 41 days with three different diets: (i) CONTROL diet (CTRL), with a commercial-like formulation; (ii) LB-CB diet, with a 10 % inclusion of microalgal product; (iii) LB-CBplus diet, with a 10 % inclusion of the same product but enzymatically hydrolysed to increase the bioavailability of the nutrients. The results obtained show that the use of these microalgal products leads an overall improvement in productive parameters in terms of growth (15 % in SGR) and feed efficiency (11 %), as well as a significant reduction in circulating cortisol with the LB-CBplus diet. Observations on plasma and liver metabolites, and particularly on hepatic metabolic enzymes, collectively indicate that microalgae supplementation of feed lead to a better use of carbohydrates as a source of energy in the liver and other tissues, potentially sparing triglycerides within this tissue, and a channelling hepatic triglycerides to fuels growth. Finally, the specimens fed the supplemented diets experienced a substantial improvement in intestinal health, achieved by longer intestines, a higher transepithelial resistance and better apparent permeability measured by electrophysiological methods, especially those fed LB-CBplus, which could explain the increase in productive performance by improving nutrient assimilation. In conclusion, this study shows that the experimental feeds, especially the one containing biotechnologically treated microalgae, are suitable for improving some important indicators of growth performance and physiological condition of gilthead seabream, thus revealing the potential for their inclusion in new functional feeds for this species at an advanced stage of the production cycle.

Objetivo: Un procedimiento para la gestión integrada de riesgos en la Universidad de las Ciencias Informáticas, La Habana, Cuba, como parte del fortalecimiento del sistema de control interno. Métodos: analítico-sintético, enfoque de sistema y estadística descriptiva. Principales resultados: el procedimiento se distingue por la forma de identificación, análisis y cuantificación de los riesgos que pueden ocurrir en cada uno de los procesos y sus actividades, y que impactan negativamente en el cumplimiento de los objetivos, la protección de los recursos y el cumplimiento del marco legal y regulatorio, para poder alcanzar los objetivos estratégicos y de trabajo. Se distingue también la determinación de los objetivos de control y su plan de prevención. Conclusiones: se muestran los resultados de la aplicación parcial del procedimiento en la Dirección de Control Interno del centro; se identificaron 15 riesgos y 48 causas asociadas a estos. Del análisis, los riesgos determinados fueron: cuatro moderados, siete bajos y dos triviales, de los cuales se establecieron seis riesgos relevantes, a los que se les realizó un análisis integrado para determinar cinco objetivos de control y 12 acciones.

Introducción. el presente trabajo, muestra la descripción de los métodos de obtención empleados para lograr piezocerámicas libres de plomo KNN dopadas: (K0.5Na0.5)0.95La0.05(Nb0.9Ti0.05)O2.9 y (K0.44Na0.52Li0.04)0.97La0.01Nb0.9Ta0.103 y la caracterización física de estos. El objetivo fue adquirir un método de obtención reproducible que propiciará buenas propiedades físico-químicas en los sistemas empleados y emplear nuevos dopantes como el Ti, de un menor precio en el mercado, y el La, no trabajados hasta el momento en la literatura consultada, para modificar y controlar sus propiedades físico-químicas. Métodos. Se emplea un método combinado de reacción del crecimiento del grano, (RTGG), para la obtención del precursor NaNbO3 y partiendo de éste lo hacemos reaccionar mediante estado sólido con los demás reactivos simplificando métodos existentes, y la caracterización: dieléctrica, transiciones de fases, caracterización estructural por Difracción de rayos X, y microscopia de piezofuerza (PFM). Resultados. Se obtienen piezocerámicas dopadas con Ti-La, fotoluminicentes con buena potencia de emisión de luz azul y piezoeléctricas KNN dopadas Li- La-Ta. En ambas composiciones presentadas; el dopar con La, se regula el crecimiento del grano y modifica las propiedades dieléctricas y hace disminuir las temperaturas de transición. En el compuesto KNN dopado con Li-La-Ta se obtiene coexistencia de fases a temperatura ambiente y buenas propiedades dieléctricas y cierta anisotropía en la orientación de los dominios. Los resultados experimentales realizados por (PFM), demuestran excelentes constantes piezoeléctricas def = 166 pCN-1 comparados con las mejores cerámicas PZT. Conclusiones: los resultados presentados potencian la utilización de éstos como emisores de luz ferroeléctricos, así como transductores libres de plomo. Ambas composiciones, aún no se han homologado internacionalmente.

Aflatoxin B1 (AFB1) is a mycotoxin often present in food. This study aimed to understand the physiological effects of AFB1 on the seabream (Sparus aurata) gastrointestinal system. In a first in vitro approach, we investigated ion transport using the short-circuit current (Isc) technique in Ussing chambers in the anterior intestine (AI). Application of apical/luminal AFB1 concentrations of 8 and 16 μM to healthy tissues was without effect on tissue transepithelial electrical resistance (TER), and apparent tissue permeability (Papp) was measured using fluorescein FITC (4 kD). However, it resulted in dose-related effects on Isc. In a second approach, seabream juveniles fed with different AFB1 concentrations (1 and 2 mg AFB1 kg−1 fish feed) for 85 days showed significantly reduced gill Na+/K+-ATPase (NKA) and H+-ATPase (HA) activities in the posterior intestine (PI). Moreover, dietary AFB1 modified Isc in the AI and PI, significantly affecting TER in the AI. To understand this effect on TER, we analyzed the expression of nine claudins and three occludins as markers of intestinal architecture and permeability using qPCR. Around 80% of the genes presented significantly different relative mRNA expression between AI and PI and had concomitant sensitivity to dietary AFB1. Based on the results of our in vitro, in vivo, and molecular approaches, we conclude that the effects of dietary AFB1 in the gastrointestinal system are at the base of the previously reported growth impairment caused by AFB1 in fish.

Abstract 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.

La aceptación de los sistemas informáticos es determinada por las personas que finalmente lo utilizarán, si los mismos no son fáciles de usar, los usuarios no los quieren y en el peor de los casos no serán utilizados. Por lo que no es bueno ocuparse de la facilidad de uso de un producto una vez liberado. El objetivo de este trabajo es definir qué criterios pueden ser utilizados por los programadores y evaluadores de software para medir la facilidad de uso del entorno de escritorio de la Distribución Cubana de GNU/LINUX NOVA de forma que contribuyan a la detección temprana de errores de funcionamiento y de diseño. En esta investigación se analizan los factores de fracaso en el desarrollo de sistemas de información y las ventajas que poseen los proyectos de software libre al tener al usuario final como parte del equipo de desarrollo. Finalmente se hace una propuesta de métricas para evaluar la usabilidad basadas en el modelo de calidad de software libre del Centro de Nacional de Desarrollo e Investigación en tecnologías libres. La usabilidad es una condición necesaria para la supervivencia de productos de software, si estos no son fáciles de usar la gente no los quiere

Based on a double-phase methodology (grouping by cluster method and costing) the costs of three activities of cacao establishment and annual management in San Vicente de Chucuri and El Carmen de Chucuri (Santander, Colombia) were structured. The grouping phase identified two productive typologies, one with low technification level and another with a medium level; moreover, technification levels were corroborated through cost structuring, in which, for all the activities, the medium technification typology generated higher average values than the low one. General cost structures showed that the most important item is labor, followed by inputs and plant material. The disaggregation of costs into monetary and non-monetary (implicit cost) showed that producers with low technification and low frequency of input use present 35% of non-monetary costs per tree, while producers with some level of crop management and relatively high execution of activities have a slightly higher non-monetary cost, 45% of the average total cost per tree. Within non-monetary costs, the labor (mainly family labor) contributed, on average, to 34% of the total cost structures, which constitutes a risk management factor when defining the financial equilibrium point of the cacao production activity.

Large branchiopods has been distributed in temporary waters around the world, but the knowledge about these organisms in Colombia is poorly known, especially leptesteriids, we report a new record of the Clam Shrimp Leptestheria venezuelica Daday, 1923 from the north of Colombia.

Calcium balance is of paramount importance for vertebrates. In fish, the endocrine modulators of calcium homeostasis include the stanniocalcin (STC), and some members of the parathyroid hormone (PTH) family, such as the PTH-related protein (PTHrP), acting as antagonists. STC is ubiquitously expressed in higher vertebrates. In turn, bony fish exhibit specific STC-producing glands named the corpuscles of Stannius (CS). Previous studies pointed to a calcium-sensing receptor (CaSR) involvement in the secretion of STC, but little is known of the involvement of other putative regulators. The CS provides a unique model to deepen the study of STC secretion. We developed an ex vivo assay to culture CS of fish and a competitive ELISA method to measure STC concentrations. As expected, STC released from the CS responds to CaSR stimulation by calcium, calcimimetics, and calcilytic drugs. Moreover, we uncover the presence (by PCR) of two PTHrP receptors in the CS, e.g., PTH1R and PTH3R. Thus, ex vivo incubations revealed a dose-response inhibition of STC secretion in response to PTHrP at basal Ca2+ concentrations. This inhibition is achieved through specific and reversible second messenger pathways (transmembrane adenylyl cyclases and phospholipase C), as the use of specific inhibitors highlights. Together, these results provide evidence for endocrine modulation between two antagonist hormones, STC and PTHrP.

This article focus on political science as a matter of study in the programs of the National Academy for Political and Strategic Studies, in order to explain the reason of including this discipline, particularly in its relation with security and defense. It is focused on the object of study of political science, thus delivering precisions about the concept of politics among others related. It also emphasizes some aspects that have been important in this discipline, including some modern epistemological debates, and also open the scope of possibilities that today can be offered as matters of study in a world yielded to the dynamics of the globalization.

En este artículo se lleva a cabo un breve resumen de los dieciséis años de funcionamiento del Museo Histórico Municipal de Teba, desde su fundación en el año 2000. Se destacan los trámites burocráticos que llevaron a su reconocimiento legal, las principales actividades desarrolladas desde entonces, la importante participación del Museo en la vida cultural del pueblo y las modificaciones que se han producido en la institución en estos años.

The implementation of the new law No 20.424 that modernizes the Chilean MOD, is an important milestone, because allows that the functions of a Ministry of Defense may be institutionalized in an effective way under the framework of a democratic system. Among the contents of the law, we can found a clear definition of the responsibilities of the Ministry as a tool of the political authority to conduct the national Defense and, in the other hand, they depicts a set of action areas that makes possible the adaptation of values and principles of the Social Corporative Responsibility as a paradigm of the new perspective of sustained development to which the defense sector may be added tuned with the ministerial statement in 2008, and thus contributing to the configuration of a new and different model for civil- military relations. in an exploratory way, this work goes through significant aspects of this relationship, their links with the SCR and the legal issues involved therein. The alternative to go deeper in other related studies about the development and application of this model. Remains open.

The initiative of the Government in order to move towards a National Defense Policy, as it was expressed by the Chilean Minister of National Defense, requires a broad discussion regarding these public policy and diplomatic instruments. Therefore, an analysis of the relevant concepts and contents of some of the existing strategies and the possible requirements of the country to this regard are offered for discussion.

The occurrence of the Afro-Asian freshwater cyclopoid copepod Mesocyclops aspericornis in the Gaira River, Magdalena, northern Colombia, represents the first record in the area and expands its known distributional range in South America. The specimens examined are described and compared with available morphological data.The variability of this species is confirmed among American and Afro-Asian populations but it was observed also between two Colombian populations. This record contributes to track the advancement of this introduced species in the Americas.

The coastal planktonic calanoid copepod Pseudodiaptomus cokeri González & Bowman, 1965 was found off Rodadero Bay, northern Colombia. A comparative morphological analysis of Colombian specimens suggests a close affinity with other populations from the Caribbean islands. This is the first record of P. cokeri from Colombia and the third record of the genus from this country. It supports the notion that its distributional range does not overlap with that of P. pelagicus Herrick, 1884 in the Northwestern Tropical Atlantic; P. cokeri is a Caribbean species reaching as far north as Belize, whereas P. pelagicus is restricted to the southern Gulf of Mexico.

Within a scenario of increasing atmospheric CO2 and ocean acidification (OA), it is highly relevant to investigate its impacts not only on fish performance but also on fish intestinal microbiome and how that reflects on host performance and health. The main objective of this study was to establish if the intestinal microbiota of the sea bream (Sparus aurata) was affected by high level of CO2 in line with the predictions for this century. The bacterial communities of the intestinal fluid were characterized in animals kept at the present-day level of CO2 (400 μatm) and in animals switched to high CO2 (1200 μatm) for 1 month. Bacterial taxa identification was based on molecular methods, using the DNA coding for the 16S ribosomal RNA and primers targeting the regions V1–V3. Amplicons obtained from DNA samples of animals in the same tank were combined, cloned to obtain a bacterial DNA library, and the clones were sequenced. No significant differences were found between the two treatments for alpha diversity. However, beta diversity analysis revealed distinct dysbiosis in response to hypercapnia, with phylum Firmicutes absent from the bacterial communities of fish exposed to 1200 μatm CO2, whereas Proteobacteria relative abundance was increased at elevated CO2, due to the presence of Gammaproteobacteria (Vibrionaceae and Alteromonadaceae), a class not present in the control samples. This study provides a first glimpse at the impact of OA in fish intestinal microbiota and highlights potential downstream effects to the general condition of fishes under hypercapnia.

Marine fish contribute to the carbon cycle by producing mineralized intestinal precipitates generated as by-products of their osmoregulation. Here we aimed at characterizing the control of epithelial bicarbonate secretion and intestinal precipitate presence in the gilthead sea bream in response to predicted near future increases of environmental CO2. Our results demonstrate that hypercapnia (950 and 1800 μatm CO2) elicits higher intestine epithelial HCO3- secretion ex vivo and a subsequent parallel increase of intestinal precipitate presence in vivo when compared to present values (440 μatm CO2). Intestinal gene expression analysis in response to environmental hypercapnia revealed the up-regulation of transporters involved in the intestinal bicarbonate secretion cascade such as the basolateral sodium bicarbonate co-transporter slc4a4, and the apical anion transporters slc26a3 and slc26a6 of sea bream. In addition, other genes involved in intestinal ion uptake linked to water absorption such as the apical nkcc2 and aquaporin 1b expression, indicating that hypercapnia influences different levels of intestinal physiology. Taken together the current results are consistent with an intestinal physiological response leading to higher bicarbonate secretion in the intestine of the sea bream paralleled by increased luminal carbonate precipitate abundance and the main related transporters in response to ocean acidification.

Several studies in fish have shown that aflatoxin B1 (AFB1) causes a disparity of species-dependent physiological disorders without compromising survival. We studied the effect of dietary administration of AFB1 (2 mg AFB1 kg−1 diet) in gilthead seabream (Sparus aurata) juveniles in combination with a challenge by stocking density (4 vs. 40 g L−1). The experimental period duration was ten days, and the diet with AFB1 was administered to the fish for 85 days prior to the stocking density challenge. Our results indicated an alteration in the carbohydrate and lipid metabolites mobilization in the AFB1 fed group, which was intensified at high stocking density (HSD). The CT group at HSD increased plasma cortisol levels, as expected, whereas the AFB1-HSD group did not. The star mRNA expression, an enzyme involved in cortisol synthesis in the head kidney, presented a ninefold increase in the AFB1 group at low stocking density (LSD) compared to the CT-LSD group. Adenohypophyseal gh mRNA expression increased in the AFB1-HSD but not in the CT-HSD group. Overall, these results confirmed that chronic AFB1 dietary exposure alters the adequate endocrinological physiological cascade response in S. aurata, compromising the expected stress response to an additional stressor, such as overcrowding.

Plankton samples obtained from the lagoon system Laguna Navío Quebrado, in northern Colombia, yielded male and female specimens of an undescribed cyclopoid copepod of the genus Halicyclops. The new species belongs to the highly diverse and widely distributed thermophilus-complex. It closely resembles H. clarkei Herbst, 1982 from Louisiana and H. bowmani Rocha & Iliffe, 1993 from Bermuda. These species share the same armature of P1-P4EXP3, with a 3443 spine formula and the terminal antennary segment with 5 setae. However, H. gaviriai sp. n. can be separated from both H. clarkei and H. bowmani by the morphology of the anal pseudoperculum, the proportions of the fourth antennulary segment, the length of the inner basipodal spine of P1, the P1EXP/inner basipodal spine inner length ratio and the length/width ratio of the caudal rami. This is the third species of Halicyclops recorded from Colombia and the first one described from this country. With the addition of H. gaviriai sp. n., the number of species of Halicyclops known from the Neotropics increases to 19. The regional diversity of the genus is probably underestimated.

Plankton samples from Laguna Navio Quebrado, La Guajira, northern Colombia, yielded male and female specimens of an harpacticoid copepod that was first identified as the widely distributed species Nitokra affinis Gurney, 1927 for which at least four subspecies have been described from different geographic areas. A more detailed examination of the Colombian specimens revealed that it differs from the other morphs so far considered as subspecies. The Colombian specimens differ from the other four known subspecies in the following aspects: (1) rostrum with long projection, (2) relatively long exopod of P1, almost as long as first endopodal segment, (3) endopodal and exopodal rami of P2 equally long, (4) a reduced number of endopodal setal elements of the male P5. It also differs from N. a. californica Lang in details of the ornamentation of the urosomites. Descriptions and illustrations of this new subspecies, the first one described from the Neotropical region, are presented together with a key to the five known subspecies of Nitokra affinis. As in many other cases of presumedly widespread species of harpacticoids, it is possible that N. affinis represents a species complex with more restricted distributional patterns, a notion that certainly deserves further study.

The occurrence of Elaphoidella grandidieri (Guerne and Richard 1893) in Ciénaga Grande de Santa Marta, Colombia, is reported for the first time. The specimens are described and compared with literature data. The Colombian specimens are similar to those of previously described from Japanese populations, presenting strong spinulation of P2 exopod and absent inner seta on the first endopodal segment of P4. Nevertheless, this species presents some differences with the previous report. The present observations support the theory that Elaphoidella grandidieri might be a complex of species, reinforcing the necessity of a revision of the species.

Nine species of cladocerans are newly recorded from the Ciénaga Grande de Santa Marta Magdalena Department and of these, five of them are new to Colombia (Dunhevedia crassa, Simocephalus vetuloides, Ilyocriptus paranaensis paranaensis, Nicsmirnovius fitzpatricki and Coronatella monacantha). The known number of Cladocera (45 species) in Ciénaga Grande de Santa Marta represents about the half of reported species in Colombia. Brief descriptions and illustrations of species, including distribution, are given.

Clostridium difficile is the causative agent of the most frequently reported nosocomial diarrhea worldwide. The high incidence of recurrent infection is the main clinical challenge of C. difficile infections (CDI). Formation of C. difficile spores of the epidemic strain R20291 has been shown to be essential for recurrent infection and transmission of the disease in a mouse model. However, the underlying mechanisms of how these spores persist in the colonic environment remains unclear. In this work, we characterized the adherence properties of epidemic R20291 spores to components of the intestinal mucosa, and we assessed the role of the exosporium integrity in the adherence properties by using cdeC mutant spores with a defective exosporium layer. Our results showed that spores and vegetative cells of the epidemic R20291 strain adhered at high levels to monolayers of Caco-2 cells and mucin. Transmission electron micrographs of Caco-2 cells demonstrated that the hair-like projections on the surface of R20291 spores are in close proximity with the plasma membrane and microvilli of undifferentiated and differentiated monolayers of Caco-2 cells. Competitive-binding assay in differentiated Caco-2 cells suggests that spore-adherence is mediated by specific binding sites. By using spores of a cdeC mutant we demonstrated that the integrity of the exosporium layer determines the affinity of adherence of C. difficile spores to Caco-2 cells and mucin. Binding of fibronectin and vitronectin to the spore surface was concentration-dependent, and depending on the concentration, spore-adherence to Caco-2 cells was enhanced. In the presence of an aberrantly-assembled exosporium (cdeC spores), binding of fibronectin, but not vitronectin, was increased. Notably, independent of the exosporium integrity, only a fraction of the spores had fibronectin and vitronectin molecules binding to their surface. Collectively, these results demonstrate that the integrity of the exosporium layer of strain R20291 contributes to selective spore adherence to components of the intestinal mucosa.

BACKGROUND:Marine species have colonized extreme environments during evolution such as freshwater habitats. The amphidromous teleost fish, Galaxias maculatus is found mainly migrating between estuaries and rivers, but some landlocked populations have been described in lakes formed during the last deglaciation process in the Andes. In the present study we use mtDNA sequences to reconstruct the historical scenario of colonization of such a lake and evaluated the osmoregulatory shift associated to changes in habitat and life cycle between amphidromous and landlocked populations. RESULTS:Standard diversity indices including the average number of nucleotide differences (Π) and the haplotype diversity index (H) indicated that both populations were, as expected, genetically distinctive, being the landlocked population less diverse than the diadromous one. Similarly, pairwise GST and NST comparison detected statistically significant differences between both populations, while genealogy of haplotypes evidenced a recent founder effect from the diadromous stock, followed by an expansion process in the lake. To test for physiological differences, individuals of both populations were challenged with a range of salinities from 0 to 30 ppt for 8 days following a period of progressive acclimation. The results showed that the landlocked population had a surprisingly wider tolerance to salinity, as landlocked fish survival was 100% from 0 to 20 ppt, whereas diadromous fish survival was 100% only from 10 to 15 ppt. The activity of ATPase enzymes, including Na+/K+-ATPase (NKA), and H+-ATPase (HA) was measured in gills and intestine. Activity differences were detected between the populations at the lowest salinities, including differences in ATPases other than NKA and HA. Population differences in mortality are not reflected in enzyme activity differences, suggesting divergence in other processes. CONCLUSIONS:These results clearly demonstrate the striking adaptive changes of G. maculatus osmoregulatory system, especially at hyposmotic environments, associated to a drastic shift in habitat and life cycle at a scale of a few thousand years.

There is a constant need to find feed additives that improve health and nutrition of farmed fish and lessen the intestinal inflammation induced by plant-based ingredients. The objective of this study was to evaluate the effects of adding an organic acid salt to alleviate some of the detrimental effects of extreme plant-ingredient substitution of fish meal (FM) and fish oil (FO) in gilthead sea bream diet. Three experiments were conducted. In a first trial (T1), the best dose (0.4%) of sodium butyrate (BP-70 ®NOREL) was chosen after a short (9-weeks) feeding period. In a second longer trial (T2) (8 months), four diets were used: a control diet containing 25% FM (T2-D1) and three experimental diets containing 5% FM (T2-D2, T2-D3, T2-D4). FO was the only added oil in D1, while a blend of plant oils replaced 58% and 84% of FO in T2-D2, and T2-D3 and T2-D4, respectively. The latter was supplemented with 0.4% BP-70. In a third trial (T3), two groups of fish were fed for 12 and 38 months with D1, D3 and D4 diets of T2. The effects of dietary changes were studied using histochemical, immunohistochemical, molecular and electrophysiological tools. The extreme diet (T2-D3) modified significantly the transcriptomic profile, especially at the anterior intestine, up-regulating the expression of inflammatory markers, in coincidence with a higher presence of granulocytes and lymphocytes in the submucosa, and changing genes involved in antioxidant defences, epithelial permeability and mucus production. Trans-epithelial electrical resistance (Rt) was also decreased (T3-D3). Most of these modifications were returned to control values with the addition of BP-70. None of the experimental diets modified the staining pattern of PCNA, FABP2 or ALPI. These results further confirm the potential of this additive to improve or reverse the detrimental effects of extreme fish diet formulations.

The occurrence of Guernella raphaelis Richard, 1892 in Ciénaga Grande de Santa Marta, Colombia, is reported. The specimens are briefly described and compared with literature data. The Colombian specimens are very similar to previously described Brazilian and Argentinean populations, presenting four setae on the inner distal lobe of trunk limb I and ciliated lamella on postabdominal claws. On the other hand, they differ from New Guinean specimens which present three setae on the inner lobe of trunk limb I. The present observations support the idea that Guernella raphaelis could be a complex of species, reinforcing the necessity of a revision of this genus.