Feeding behaviour and digestion physiology in larval fish – current knowledge and gaps and bottlenecks in research

Food uptake follows rules defined by feeding behaviour that determines the kind and quantity of food ingested by fish larvae as well as how live prey and food particles are detected, captured and ingested. Feeding success depends on the progressive development of anatomical characteristics and physiological functions and on the availability of suitable food items throughout larval development. The fish larval stages present eco-morpho-physiological features very different from adults and differ from one species to another. The organoleptic properties, dimensions, detectability, movements characteristics and buoyancy of food items are all crucial features that should be considered, but is often ignored, in feeding regimes. Ontogenetic changes in digestive function lead to limitations in the ability to process certain feedstuffs. There is still a lack of knowledge about the digestion and absorption of various nutrients and about the ontogeny of basic physiological mechanisms in fish larvae, including how they are affected by genetic, dietary and environmental factors. The neural and hormonal regulation of the digestive process and of appetite is critical for optimizing digestion. These processes are still poorly described in fish larvae and attempts to develop optimal feeding regimes are often still on a ‘trial and error’ basis. A holistic understanding of feeding ecology and digestive functions is important for designing diets for fish larvae and the adaptation of rearing conditions to meet requirements for the best presentation of prey and microdiets, and their optimal ingestion, digestion and absorption. More research that targets gaps in our knowledge should advance larval rearing

Observational Constraints on the Common Envelope Phase

The common envelope phase was first proposed more than forty years ago to explain the origins of evolved, close binaries like cataclysmic variables. It is now believed that the phase plays a critical role in the formation of a wide variety of other phenomena ranging from type Ia supernovae through to binary black holes, while common envelope mergers are likely responsible for a range of enigmatic transients and supernova imposters. Yet, despite its clear importance, the common envelope phase is still rather poorly understood. Here, we outline some of the basic principles involved, the remaining questions as well as some of the recent observational hints from common envelope phenomena - namely planetary nebulae and luminous red novae - which may lead to answering these open questions.Comment: 29 pages, 8 figures. To appear in the book "Reviews in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds. Kabath, Jones and Skarka; publisher Springer Nature) funded by the European Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul" 2017-1-CZ01-KA203-03556

Genomic Ancestry, CYP2D6, CYP2C9, and CYP2C19 Among Latin Americans

We present the distribution of CYP2D6, CYP2C9, and CYP2C19 variants and predicted phenotypes in 33 native and admixed populations from Ibero-America (n > 6,000) in the context of genetic ancestry (n = 3,387). Continental ancestries are the major determinants of frequencies of the increased-activity allele CYP2C19*17 and CYP2C19 gUMs (negatively associated with Native American ancestry), decreased-activity alleles CYP2D6*41 and CYP2C9*2 (positively associated with European ancestry), and decreased-activity alleles CYP2D6*17 and CYP2D6*29 (positively associated with African ancestry). For the rare alleles, CYP2C9*2 and CYPC19*17, European admixture accounts for their presence in Native American populations, but rare alleles CYP2D6*5 (null-activity), CYP2D6-multiplication alleles (increased activity), and CYP2C9*3 (decreased-activity) were present in the pre-Columbian Americas. The study of a broad spectrum of Native American populations from different ethno-linguistic groups show how autochthonous diversity shaped the distribution of pharmaco-alleles and give insights on the prevalence of clinically relevant phenotypes associated with drugs, such as paroxetine, tamoxifen, warfarin, and clopidogrel

Estructura de la comunidad de peces en el sistema Candelaria-Panlau, Campeche, México

Se describe el comportamiento de los parámetros de temperatura, salinidad, transparencia del agua y temperatura ambiente, y de la abundancia y diversidad de la comunidad del peces del sistema Candelaria-Panlau en escalas temporal y espacial. Los trabajos de campo se realizaron de manera mensual en cinco estaciones entre abril de 1993 Y abril de 1994. La comunidad de peces quedó representada por 50 especies con 7 926 organismos y 144.7 kg de peso. Los valores de abundancia y diversidad de la comunidad fueron: 0.09 ind/m2, 1.61 g/m2 18.25 g/ind, H'n = 1.879, J = 0.475 Y D = 5.681. Las especies con dominio ecológico fueron: Cathorops melanopus, Diapterus rhombeus, Anchoa mitchilli, Sphoeroides testudineus, Bairdiella chrysura, B. ronchus, Cynoscion arenarius, y C. nebulosus, que en conjunto representan el 90.9 % en número y el 78.9 % en peso de la captura total. Las matrices de valores de los parámetros ambientales y de abundancia numérica de la comunidad de peces, fueron sometidas a un análisis de factores con el método dé extracción de componentes principales, su representación gráfica confmna la definición de especies dominantes y demuestra que la salinidad, estación cinco y mes de febrero son los componentes que caracterizan al sistema y a la comunidad de peces.The environmental and ecological patterns of tbe fish community in Candelaria-Panlau system (Mexico) are described. Parameters of the water temperature, salinity and transparency, and density, biomass and diversity of the fish cornmunity were analyzed. Between April 1993 and April 1994 five stations were sampled monthly. The fish community had 50 species (7 926 individuals, 144.7 kg of weight). The abundance and diversity values for the fish cornmunity were: 0.09 ind/m2 ; 1.61 g/m2; 18.25 g/ind; H'n = 1.879; J = 0.475 and D = 5.681. The species with ecological dominance were: Cathorops melanopus, Diapterus rhombeus, Anchoa mitchilli, Sphoeroides testudineus, Bairdiella chrysura, B. ronchus, Cynoscion arenarius, and C. nebulosus. The matrixes of the environmental parameters and of fish abundance, were tested with a factor analysis (principal components extraction method); its graphical representation confmns the dominant species and indicates that salinity, station number five and February are tbe components that characterize the system and the fish community

Estructura de la comunidad de peces en el sistema Candelaria-Panlau, Campeche, México

Se describe el comportamiento de los parámetros de temperatura, salinidad, transparencia del agua y temperatura ambiente, y de la abundancia y diversidad de la comunidad del peces del sistema Candelaria-Panlau en escalas temporal y espacial. Los trabajos de campo se realizaron de manera mensual en cinco estaciones entre abril de 1993 y abril de 1994. La comunidad de peces quedó representada por 50 especies con 7 926 organismos y 144.7 kg de peso. Los valores de abundancia y diversidad de la comunidad fueron: 0.09 ind/m², 1.61 g/m² 18.25 g/ind, H’n = 1.879, J = 0.475 y D = 5.681. Las especies con dominio ecológico fueron: Cathorops melanopus, Diapterus rhombeus, Anchoa mitchilli, Sphoeroides testudineus, Bairdiella chrysura, B. ronchus, Cynoscion arenarius, y C. nebulosus, que en conjunto representan el 90.9 % en número y el 78.9 % en peso de la captura total. Las matrices de valores de los parámetros ambientales y de abundancia numérica de la comunidad de peces, fueron sometidas a un análisis de factores con el método de extracción de componentes principales, su representación gráfica confirma la definición de especies dominantes y demuestra que la salinidad, estación cinco y mes de febrero son los componentes que caracterizan al sistema y a la comunidad de peces.The environmental and ecological patterns of the fish community in Candelaria-Panlau system (Mexico) are described. Parameters of the water temperature, salinity and transparency, and density, biomass and diversity of the fish community were analyzed. Between April 1993 and April 1994 five stations were sampled monthly. The fish community had 50 species (7 926 individuals, 144.7 kg of weight). The abundance and diversity values for the fish community were: 0.09 ind/m² ; 1.61 g/m²; 18.25 g/ind ; H'n = 1.879; J = 0.475 and D = 5.681. The species with ecological dominance were: Cathorops melanopus, Diapterus rhombeus, Anchoa mitchilli, Sphoeroides testudineus, Bairdiella chrysura, B. ronchus, Cynoscion arenarius, and C. nebulosus. The matrixes of the environmental parameters and of fish abundance, were tested with a factor analysis (principal components extraction method); its graphical representation confirms the dominant species and indicates that salinity, station number five and February are the components that characterize the system and the fish community

Predicting the volumetric variation due to changes in suction, applied stress and swelling pressure

The settlements produced by the load transmitted to the structure on expansive soils, and those calculated by the classical theories of soil mechanics, are different because the swelling pressure acts inversely to the applied stress. In this paper we describe a procedure to determine a volumetric variation coefficient by hydration (αh) which considers the expansive soil behaviour. In order to do this, it is necessary to know the soil’s initial water content, the swelling pressure, and the applied stress. Soil suction and swelling pressure were measured with filter paper technique and a mechanical oedometer, respectively. Unsaturated undisturbed samples of expansive soil were used. The water content was varied, starting from 0%, with increments of 5.5% to reach 38%. Furthermore, we present a set of curves that show the magnitude of the coefficient (αh) associated to a water content, and the relationship between applied stress and swelling pressure. The results show that the variation of the coefficient under different initial water contents ranges between 0% to 22%. This is because water is strongly attracted by clay minerals, but this attraction decreases as water layers are father from the surface of clay minerals, thus decreasing its swelling potential

Memoria y Revolución. Programa Diálogos del Pensamiento 104

En esta emisión especial por la conmemoración de la Revolución Mexicana, invitamos a José Rojas y a Jaime Tamayo, ambos expertos en movimientos sociales, a discutir sobre cuáles fueron los logros de la revolución y cuál es el estado actual de estos en el México contemporáneo con un gobierno cada vez más neoliberal y proclive a realizar reformas al Estado que pretenden beneficiar a todos, menos a los más necesitados. Si bien la Revolución dio respuesta a algunas demandas, lo que hemos visto desde hace ya algunos sexenios es la desmantelación, lenta pero segura, de las instituciones surgidas directamente de este proceso histórico, tales como la educación pública y gratuita-, el salario mínimo, los recursos del subsuelo en materia de minerales con las concesiones mineras y ahora con la inminente privatización del petróleo; que de acuerdo con el Dr. Jaime Tamayo tendrá como resultado el aumento de impuestos o la reducción de todos los servicios que brinda el Estado, privatizando hasta el último servicio público. Nuestros invitados no dudan en afirmar que más que asuntos pendientes de la Revolución, lo que presenciamos es el retroceso de algunos derechos y privilegios ganados, que habría que comenzar a defender, y para ello es necesario conocerlos. ¿El estado mexicano actual es todavía heredero de la Revolución mexicana? ¿Qué símiles se pueden encontrar entre el Estado Porfirista y el actual? ¿Existe un riesgo real y latente de un nuevo levantamiento revolucionario como resultado de las profundas desigualdades aún tan presentes en la sociedad mexicana del siglo XXI? ¿Cabe considerar la celebración, o la indiferencia, en relación con esta fecha histórica, un indicador de la posición ideológica de quien festeja o de quien deliberadamente olvida? ¿Por qué es importante la memoria histórica