Stable isotope analysis indicates resource partitioning and trophic niche overlap in larvae of four tuna species in the Gulf of Mexico

In this study we assessed the trophic ecology of bluefin tuna Thunnus thynnus larvae from the Gulf of Mexico, together with the co-occurring larvae of blackfin tuna T. atlanticus, bullet tuna Auxis rochei, and skipjack Katsuwonus pelamis, using both bulk-tissue stable isotope analysis (SIAbulk) and compound-specific analysis of amino acids (CSIAAA). Bulk nitrogen (δ15Nbulk) and carbon (δ13Cbulk) values differed significantly among species, suggesting partitioning of resources due to an adaptive process allowing these tunas to share the ecosystem’s trophic resources during this early life period. K. pelamis had the largest isotopic niche width, likely due to piscivorous feeding at an earlier age compared to the other species, with an isotopic niche overlap of 17.5% with T. thynnus, 15.8% with T. atlanticus, and 31.2% with A. rochei. This trophic overlap suggests a mix of competition and trophic differentiation among these 4 species of tuna larvae. Higher nitrogen isotopic signatures in preflexion versus postflexion larvae of T. thynnus measured using both SIAbulk and CSIAAA indicate maternal isotopic transmission, as well as ‘capital breeder’-like characteristics. In contrast, the nitrogen isotopic ratios of the other 3 species were similar between ontogenetic stages. These observations suggest different breeding strategies within the study area for T. atlanticus, K. pelamis, and A. rochei compared to T. thynnus. No significant differences were observed among the 4 species’ trophic positions (TPs) estimated by CSIAAA, whereas a higher TP was observed for T. thynnus by SIAbulk. These differences in TP estimation may be attributed to discrepancies in baseline estimates.Postprint2,48

What do rates of deposition of dental cementum tell us? Functional and evolutionary hypotheses in red deer.

Cementum is a bone connective tissue that provides a flexible attachment for the tooth to the alveolar bone in many mammalian species. It does not undergo continuous remodelling, unlike non-dental bone, which combined with its growth pattern of seasonal layering makes this tissue uniquely suitable as a proxy for tracking changes in body repair investment throughout an animal´s life. We tested functional and sexual selection hypotheses on the rate of cementum deposition related to the highly polygynous mating strategy of red deer. We used a sample of 156 first lower molars from wild Scottish red deer of known age between 1 and 17 years old, approximately balanced by sex and age class. Cementum deposition on the inter-radicular pad increased with age at a constant average rate of 0.26 mm per year, with no significant differences between sexes. Cementum deposition was independent of (i) tooth wear, other than that associated with age, and (ii) enamel and dentine micro-hardness. The results partially supported the hypothesis that the main function of cementum is the repositioning of the tooth to maintain opposing teeth in occlusion. However, teeth that had more wear or males´ teeth that had faster rates of tooth wear than those of females did not present the expected higher rates of cementum deposition

Dependencia a colistina debida a la pérdida de lipolisacáridos en Acinetobacter baumannii

Motivación: Determinar la causa genotípica de la dependencia a colistina (1) en Acinetobacter baumannii de estirpes seleccionadas resistentes a colistina, el cual es un antibiótico muy utilizado en clínica para combatir cepas múltirresistentes. Estos mutantes presentan una mutación de pérdida de función en genes esenciales para la biosíntesis del lípido A, que forma parte del lipopolisacáridos (LPS). Henry et al. demostraron que estas estirpes sin LPS tienen alterados los niveles de expresión de otros genes que dan lugar, entre otras cosas, al incremento de sistemas de transporte de lipoproteínas, fosfolípidos y exopolisacáridos para compensar la pérdida del LPS en la membrana externa (2). Por tanto, este fenómeno produce la modificación de la membrana con la consecuente resistencia a colistina y un aumento de permeabilidad.Métodos: Se utilizaron cinco cepas clínicas multirresistentes aisladas de pacientes infectados en las UCIs del hospital Virgen del Rocío, una estirpe tipo sensible. Además, se incluyó una estirpe resistente a colistina con una modificación en el LPS en lugar de ausencia del mismo. Para visualizar la dependencia a colistina, en primer lugar se realizaron ensayos E-test en placas de medio rico con Mueller Hinton Broth (MBHII), usando tiras de colistina. El efecto de dependencia a colistina se estudió en curvas de crecimiento en medio líquido MHBII en agitación a 37ºC en placas multipocillos, comparando el número de ufc/ml de la misma estirpe en ausencia o presencia de colistina a 5 μg/ml.Resultados: Todas las estipes clínicas presentaron una concentración mínima inhibitoria a colistina >256 μg/ml, mientras que la de la estirpe tipo resistente a colistina fue de 48 μg/ml y la cepa con LPS modificado fue 32 μg/ml. Sólo en las cepas sin LPS se observó un halo de mayor crecimiento alrededor de la tira en comparación a la zona alejada de la misma, lo que indica la dependencia a este antibiótico.Respecto a la curva de crecimiento, la presencia de colistina aceleró la entrada en fase exponencial en todas las estirpes en comparación al medio rico sin colistina, alcanzando 1,71 veces más crecimiento en colistina a las 24 horas.Conclusiones: Nuestros resultados muestran que la pérdida de LPS no sólo confiere resistencia a colistina si no que además crea una dependencia a este antibiótico. Sin embargo, este fenómeno de dependencia a colistina no ocurre si la resistencia se ha adquirido por modificación del LPS

Desafíos de la inclusión de estudiantes con discapacidad en la Universidad de San Carlos de GuatemalaChallenges in the inclusion of students with disabilities at the University of San Carlos of Guatemala

La Universidad de San Carlos de Guatemala (Usac), como única universidad estatal, está obligada a desarrollar procesos que permitan la inclusión de grupos vulnerados en la educación superior. Es necesario monitorear constantemente dichos procesos; por lo que se desarrolló la investigación denominada “Inclusión educativa de estudiantes con discapacidad en la Universidad de San Carlos de Guatemala: seguimiento y estudio de casos bajo la perspectiva interseccional”, durante el año 2017, con el aval del Instituto Universitario de la Mujer y el financiamiento de la Dirección General de Investigación de la Usac. El tipo de investigación fue no experimental, con un enfoque mixto de investigación, reflejado en las tendencias porcentuales de caracterización y en la valoración cualitativa de las experiencias de los estudiantes. Se utilizó el método interseccional para incorporar factores asociados a la exclusión social, como condición de discapacidad, sexo, pertenencia étnica, edad, grupo socioeconómico y orientación sexual. La muestra no probabilística, fue integrada por estudiantes con y sin discapacidad, así como por personal docente y administrativo. Los resultados evidencian la falta de un registro fidedigno de personas con discapacidad; sin embargo, los participantes brindaron información que cualitativamente puede considerarse útil para implementar acciones que permitan mejorar la inclusión por perspectiva de discapacidad con enfoque de derechos humanos. Así mismo, se busca compartir las experiencias de la comunidad universitaria de la Usac en relación con la accesibilidad en el ámbito universitario

Effect of disinfectants used in clinical facilities on the induction of the SOS response and mutation frequency in Escherichia coli

Motivation: The development of antibiotic resistance is one of the mechanism used to study adaptive evolution. Antibiotics not only select for preexisting resistant strains in a population, but they can also promote the appearance of resistant strains (1, 2). Antibiotics at high concentrations can be lethal to bacteria, but it has been shown that sub-inhibitory concentrations of some antibiotics can stimulate horizontal transfer of DNA and mutation in different chromosomal loci (1, 3). These antibiotics can increase the mutation rate through several mechanisms, such as oxidative stress and the SOS response, which is triggered by DNA damage (2, 3). In this context, we wanted to determine if commonly-used disinfectants also promote mutation. Methods: The disinfectants used were ethanol, sodium hypochlorite, chlorhexidine, silver nitrate, benzalkonium chloride, triclosan and povidone-iodine complex. The E.coli strain used was IBDS1, which includes a tetracycline gene regulated by the cI (Ind-) repressor gene, that allows us to measure the mutation rate.To study the effect of these disinfectants, the strain IBDS1 was tested with a window of concentrations very close to the minimum inhibitory concentration (MIC) by evaluating the appearance of mutants resistant to rifampicin or tetracycline (3). To determine if this effect could be linked to the induction of the SOS system, we used a plasmid which expresses the "Green Fluorescence Protein" (GFP) under the control of the promoter of the recA gene to detect when the SOS system is activated by measuring fluorescence.Results: Three of the disinfectants tested increased mutation frequency. Concentrations of 0.013 μg/ml and 0.026 μg/ml of NaClO (1/4x CMI y 1/2x MIC) increased the mutation frequency approximatly 4 fold and 0.5 μg/ml of clorhexidine (1/4x MIC) and 0.125 μg/ml of triclosan (1/4x MIC) 3 fold, approximately. In relation to the SOS system, none of the concentrations tested induced the SOS response. Conclusions: These results show that certain concentrations of sodium hypochlorite, chlorhexidine and triclosan increase the mutation frequency and therefore may facilitate the appearance of resistant strains, although it appears that this mutagenic effect is not related to the induction of the SOS system. Therefore, it would be interesting to study whether this mutagenic effects is due to the reactive oxygen species (ROS) produced by disinfectants.

LARVAL BLUEFIN TUNA (THUNNUS THYNNUS) TROPHODYNAMICS FROM BALEARIC SEA (WM) AND GULF OF MEXICO SPAWNING ECOSYSTEMS BY STABLE ISOTOPE

The present study uses stable isotopes of nitrogen and carbon (δ15N and δ13C) as trophic indicators for Atlantic bluefin tuna larvae (BFT) (6-10 mm SL) in the highly contrasting environmental conditions of the Gulf of Mexico (GOM) and the Balearic Sea (MED). The study analyzes ontogenetic changes in the food sources and trophic levels (TL) of BFT larvae from each spawning habitat. The results discuss differences in the ontogenic dietary shifts observed in the BFT larvae from the GOM and MED as well as trophodynamic differences in relation to the microzooplanktonic baselines used for estimating trophic enrichment. Significant trophic differences between the GOM and MED larvae were observed in relation to δ15N signatures in favour of the MED larvae, which may have important implications in their early life growth strategy.Versión de edito

Seasonal variability of oceanographic conditions off NW Galician waters influencing the early life trophic ecology of European hake Merluccius merluccius by stable isotope analysis

Stable isotopes of nitrogen (δ15N) and carbón (δ13C) have been used as tracers for analyzing the trophic ecology of European hake larvae collected during the winter and summer of 2012 off NW Galicia. The sampling times correspond to periods of high and low hake spawning activity, respectively. Trophic enrichment was analyzed using as baseline two different plankton size fractions, corresponding to micro- (55-200μm) and mesozooplankton (>200μm). During both seasons, the δ15N signatures of hake larvae showed higher values than the zooplankton fractions. The first survey carried out in late February was characterized by a preceding marked upwelling, low geostrophic velocities in the hydrographic circulation and an intense mixing of the water column. This environmental scenario is hypothesizing that originated a great nutrient availability for primary consumers showed its effect in the low δ15N values observed in plankton and hake larvae. During July, the environmental setting corresponded to period where the water column was stratified, an anticyclonic gyre was formed in the center of the study area that concentrated particles and weak upwelling conditions and strong geostrophic currents where found. This scenario was characterized hypothetically by low nutrient availability in which production is mainly based on regenerated nutrients which would explain the higher δ15N values found during this period. On the other hand, the greater δ13C values observed in summer in comparison to winter suggest differences in the energetic sources of carbon (Fig. 1). The discussion of results is centered in how oceanographic variability conditions signatures of stable isotope fractionation in the early life trophic food web influencing the variable trophic pathways of larval hake subject to contrasting environmental conditions, thereby affecting their larval nutritional condition as estimated by RNA/DNA ratios and the Fulton index. This study was financed by the projects: CRAMER-CTM2010-21856-CO3 y ECOPREGA-10MMA602021P

Caspase-8 inhibition represses initial human monocyte activation in septic shock model

In septic patients, the onset of septic shock occurs due to the over-activation of monocytes. We tested the therapeutic potential of directly targeting innate immune cell activation to limit the cytokine storm and downstream phases. We initially investigated whether caspase-8 could be an appropriate target given it has recently been shown to be involved in microglial activation. We found that LPS caused a mild increase in caspase-8 activity and that the caspase-8 inhibitor IETD-fmk partially decreased monocyte activation. Furthermore, caspase-8 inhibition induced necroptotic cell death of activated monocytes. Despite inducing necroptosis, caspase-8 inhibition reduced LPS-induced expression and release of IL-1β and IL-10. Thus, blocking monocyte activation has positive effects on both the pro and anti-inflammatory phases of septic shock. We also found that in primary mouse monocytes, caspase-8 inhibition did not reduce LPS-induced activation or induce necroptosis. On the other hand, broad caspase inhibitors, which have already been shown to improve survival in mouse models of sepsis, achieved both. Thus, given that monocyte activation can be regulated in humans via the inhibition of a single caspase, we propose that the therapeutic use of caspase-8 inhibitors could represent a more selective alternative that blocks both phases of septic shock at the source.Unión Europea, Ministerio de Economía y Competitividad SAF2012-39029Unión Europea, Ministerio de Economía y Competitividad SAF2015-64171REspaña,Junta de Andalucía P10-CTS-649

Del contexto cultural al funcionamiento familiar. Conocimientos compartidos y relaciones familiares en adolescentes con intento de suicidio

El objetivo de este texto es identificar y comparar la estructura semántica del dominio cultural, el conocimiento promedio y el grado de consenso cultural sobre las causas del intento de suicidio, los síntomas previos y las estrategias de prevención del intento de suicidio, además evaluar el funcionamiento familiar entre adolescentes mexicanos con y sin intento de suicidio. Se presenta un estudio mixto metodológicamente que usa la técnica de listas libres y el inventario de recursos familiares en una muestra propositiva de 65 adolescentes (13 a 18 años) divididos en dos grupos: el grupo de adolescentes con tentativa suicida y un grupo control con adolescentes estudiantes sin antecedentes de conductas suicidas. Los problemas familiares fueron la principal causa del intento suicida, mientras que la depresión y la tristeza fueron síntomas previos a una tentativa suicida en ambos grupos. La ayuda psicológica y el desarrollo de habilidades de escucha en los padres fueron señaladas como las estrategias para la prevención del suicidio. Respecto del funcionamiento familiar, los adolescentes con tentativa suicida percibieron más conflictos familiares y menor comunicación y apoyo en sus familias en comparación con el grupo control. Los resultados sugieren un conocimiento compartido culturalmente sobre las causas, los síntomas y las estrategias de prevención del intento de suicidio en los adolescentes, el cual se confirma en la percepción del funcionamiento familiar. La familia, elemento central en la cultura mexicana, debe ser considerada en las estrategias de prevención del intento de suicidio en los adolescentes en México. AIM: The aim of the study was to identify and to compare the semantic structure of the cultural domain, the average knowledge and the degree of cultural consensus regarding knowledge of suicide attempts cause, symptoms and prevention strategies to suicide attempt and the family functioning among Mexican adolescents with and without previous suicide attempt. Method: It was a mixed study, using the free-listing technique and an inventory of family resources, with a non-random sample of 65 adolescents (13-18 years) divided in two groups. The suicide attempters group and the control group were high school students, without a history of suicide behaviors. Results: Family problems were identified as the most important cause of suicide attempts in both groups, while depression and sadness were identified as symptoms prior to the suicide attempt in both groups. Psychological aid and development of listening skills in the parents were the most frequent responses regarding prevention strategies to suicide attempt. Regarding family functioning teenage suicide attempters showed more family conflict, less family communication and support than teenage non suicide attempters. Conclusions: The results suggest a same cultural knowledge background regarding causes, symptoms prior and prevention strategies to suicide attempt in Mexican adolescents. Mexican culture centered in family relationships is important to be considered in design of prevention strategies to suicide attempt in adolescence in Mexico.ITESO, A.C

Genetic connectivity between Atlantic bluefin tuna (ABFT) Larvae Spawned in the GOM and MED

Highly migratory Atlantic bluefin tuna (ABFT) is managed as two stocks, Western and Eastern. Western ABFT spawn mainly in the Gulf of Mexico (GOM) and Eastern ABFT in the Mediterranean Sea (MED) (1). Understanding connectivity between ABFT populations is important for conservation and management of this valuable fishery resource that has been exploited for centuries. ABFT are highly mixed, with multiple disciplines supporting weak structuring between Western and Eastern stocks (1). Concerning genetics, subtle structuring of ABFT populations across the Atlantic Ocean has been the conclusion of studies describing genetic tools for traceability (2,3). Larval fish provide the genetic signal of successful breeders and have occasionally been genetically characterized with juveniles (young-of-the-year, YOY) collected in nursery areas. For the first time, cooperative field collection of tuna larvae during 2014 in the main spawning area for each stock enabled us to assess the structuring of ABFT genetic diversity in a precise temporal and spatial frame exclusively through larvae (5). Partitioning of genetic diversity at nuclear microsatellite loci and in the mitochondrial control region resulted in low significant fixation indices. Individual-based clustering analysis of larval ABFT genetic diversity indicate apparent connectivity between the GOM and MED spawning grounds that could support the hypothesis of mixing of breeders belonging to different stocks.This collaborative study was supported by "ECOLATUN" PROJECT CTM2015-68473-R (MINECO/FEDER) funded by Spanish Ministry of Economy and Competitiveness; "TUNAGEN" project funded by IEO; and "BLUEFIN" project financed by IEO and Balearic Island Observing and Forecasting System (SOCIB). This research was funded by NASA (NNX11AP76G S07), the NOAA National Marine Fisheries Science Service through the Southeast Fisheries Science Center, as well as by Cooperative Institute for Marine and Atmospheric Studies under Cooperative Agreement NA15OAR43200064 at the University of Miami. There was no additional external funding received for this study. The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the author(s) and do not necessarily reflect those of NOAA or the Department of Commerce