Pulmonary ventilation–perfusion mismatch : a novel hypothesis for how diving vertebrates may avoid the bends

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Proceedings of the Royal Society B: Biological Sciences 285 (2018): 20180482, doi:10.1098/rspb.2018.0482.Hydrostatic lung compression in diving marine mammals, with collapsing alveoli blocking gas exchange at depth, has been the main theoretical basis for limiting N2 uptake and avoiding gas emboli (GE) as they ascend. However, studies of beached and bycaught cetaceans and sea turtles imply that air-breathing marine vertebrates may, under unusual circumstances, develop GE that result in decompression sickness (DCS) symptoms. Theoretical modelling of tissue and blood gas dynamics of breath-hold divers suggests that changes in perfusion and blood flow distribution may also play a significant role. The results from the modelling work suggest that our current understanding of diving physiology in many species is poor, as the models predict blood and tissue N2 levels that would result in severe DCS symptoms (chokes, paralysis and death) in a large fraction of natural dive profiles. In this review, we combine published results from marine mammals and turtles to propose alternative mechanisms for how marine vertebrates control gas exchange in the lung, through management of the pulmonary distribution of alveolar ventilation (Embedded Image) and cardiac output/lung perfusion (Embedded Image), varying the level of Embedded Image in different regions of the lung. Man-made disturbances, causing stress, could alter the Embedded Image mismatch level in the lung, resulting in an abnormally elevated uptake of N2, increasing the risk for GE. Our hypothesis provides avenues for new areas of research, offers an explanation for how sonar exposure may alter physiology causing GE and provides a new mechanism for how air-breathing marine vertebrates usually avoid the diving-related problems observed in human divers.Funding to support a portion of this work was obtained by the Fundación Oceanogràfic and by the Office of Naval Research (ONR YIP Award no. N000141410563 and Award no. N000140811220)

Identificación de técnicas de manufactura y funcionalidad de vasijas cerámicas en estudios de lámina

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Relación entre las composiciones químicas y mineralógica en los suelos de la Dehesa del Camarate (Sierra Nevada)

En este estudio aplicamos a los suelos desarrollados sobre rocas metamórficas en la Dehesa del Camarate, un programa de cálculo que parte del análisis elemental, para la obtención de la mineralogia de los suelos, la cual, a su vez, ha sido estudiada por métodos ópticos y de rayos X. Los resultados obtenidos en este estudio muestran unas grandes posibilidades a la programación del análisis elemental de los suelos.In this study, we have applied to the soil developed on metamorphic rocks located at the «Dehesa del Camarate» Grenade (Spain), a calculation program which is based at the chemical analysis to obtain the mineralogy of the soils, which have also been studied by optical methods and X-ray methods. The obtained results in this study, show great posibilities to the programation of the elemental analysis of the solis

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En este estudio aplicamos a los suelos desarrollados sobre rocas metamórficas en la Dehesa del Camarate, un programa de cálculo que parte del análisis elemental, para la obtención de la mineralogia de los suelos, la cual, a su vez, ha sido estudiada por métodos ópticos y de rayos X. Los resultados obtenidos en este estudio muestran unas grandes posibilidades a la programación del análisis elemental de los suelos.In this study, we have applied to the soil developed on metamorphic rocks located at the «Dehesa del Camarate» Grenade (Spain), a calculation program which is based at the chemical analysis to obtain the mineralogy of the soils, which have also been studied by optical methods and X-ray methods. The obtained results in this study, show great posibilities to the programation of the elemental analysis of the soils

Capacidad de realizar esprints repetidos en jugadores profesionales de fútbol vs. Fútbol sala

Objetivo: Investigar los cambios producidos ante acciones de esprines repetidos (20+20 metros con cambio de dirección ), el CMJ, la respuesta metabólica (lactato) , y la relación entre estas variables y la fuerza y resistencia en jugadores profesionales de fútbol y fútbol sala. Métodos: Jugadores profesionales (n=30, doce de fútbol sala y veinte de fútbol) completaron tres sesiones de evaluación; VO2max en tapiz rodante, el salto CMJ y la RM en sentadilla completa y finalmente, se realizó el test de RSA (6 x 40 (20+20)). Resultados: Se obtuvieron valores similares de fuerza en sentadilla, en CMJ, de LAC después de la prueba RSA y de VO2max ( 95,12 kg vs 94,73 kg ; 34,5 cm vs 35,9 cm ; 13,65 mmol vs 14,33 mmol ; 62,78 ml·kg·min-1 vs . 62,95 ml·kg·min-1 fútbol vs. fútbol sala, respectivamente). Se obtuvieron diferencias significativas cuando se analizó la pérdida de rendimiento en velocidad (total y entre los tres primeros y tres últimos bloques de esprines) y en salto (2,67% vs 4,4%**; 1,28% vs 2,1%*; 2,88% vs 6,1%**; 9,71% vs 14,3%* de fútbol vs. fútbol sala, respectivamente). Conclusiones: Ambos deportes presentan diferencias significativas en las pérdidas de rendimiento en velocidad y salto a pesar de tener valores similares de fuerza, de VO2max, de lactato tras RSA y de CMJ. Podría atribuirse a los esfuerzos propios de cada deporte y puede sugerir que debería incrementarse el volumen de entrenamiento orientado a la capacidad de realizar esfuerzos repetidos frente a otro tipo de objetivo como la mejora de la capacidad aeróbica, sobre todo a nivel profesional.To investigate the changes through repeated explosive effort sequences (20+20-m sprint with change of direction), jumping, metabolic response (lactate), as well as the relationship between these variables and fitness qualities (strength and endurance) in professional futsal and soccer players. Methods: Male players (n =30, Twelve futsal and twenty soccer players) completed three testing sessions. In the first session was measured VO2max on a motorized treadmill. In the second session was measured counter movement jump (CMJ) and full squat RM in Smith Machine. Finally, in the third session six repeated-explosive effort sequences (RES) was performed. Results: Similar values of lower limbs strength, CMJ height, LAC after RSA test and VO2max (95,12 vs. 94,73; 34,5 vs. 35,9; 13,65 vs. 14,33; 62,78 vs. 62,95 soccer vs. futsal respectively) and significant differences when are analysed the loss of performance in velocity (total and between three first and three last) and vertical jump height (2,67 vs. 4,4**; 1,28 vs. 2,1*; 2,88 vs. 6,1**; 9,71 vs. 14,3* soccer vs. futsal respectively). Conclusions: Professional futsal and soccer obtain significant differences in speed and vertical jump height (CMJ) loss despite having similar values in squat, oxygen consumption, lactate after RSA test and CMJ height. Issue that could be attributed to the characteristics of the sport. This suggests that the volume should be increased oriented ability to perform repeated sprint actions over other type of training aimed at improving aerobic capacity especially at professional level.peerReviewe

Trehalose accumulation induced during the oxidative stress response is independent of TPS1 mRNA levels in Candida albicans

Growing cells of the Candida albicans trehalose- deficient mutant tps1/tps1 were extremely sensitive to severe oxidative stress exposure (H2O2). However, their viability was not affected after saline stress or heatshock treatments, being roughly equivalent to that of the parental strain. In wild-type cells, these adverse conditions induced the intracellular accumulation of trehalose together with activation of trehalose-6P synthase, whereas the endogenous trehalose content and the corresponding biosynthetic activity were barely detectable in the tps1/tps1 mutant. The addition of cycloheximide did not prevent the marked induction of trehalose-6P synthase activity. Furthermore, the presence of H2O2 decreased the level of TPS1 mRNA expression. Hence, the conspicuous trehalose accumulation in response to oxidative stress is not induced by increased transcription of TPS1. Our results are consistent with a specific requirement of trehalose in order to withstand a severe oxidative stress in C. albicans, and suggest that trehalose accumulation observed under these conditions is a complex process that most probably involves post-translational modifications of the trehalose synthase complex

Características bioclimáticas, edafológicas y botánicas de la Sierra de Loja (Granada). II parte

The most important plant cornmunites of the Loja (Granada) mountains are described, indicating the leading species of the different cornmunities studied.Se describen las comunidades vegetales más importantes de la Sierra de Laja (Granada), indicando las especies directrices de las distintas comunidades estudiadas

Características bioclimáticas, edafológicas y botánicas de la Sierra de Loja (Granada). II parte

Se describen las comunidades vegetales más importantes de la Sierra de Laja (Granada), indicando las especies directrices de las distintas comunidades estudiadas.The most important plant cornmunites of the Loja (Granada) mountains are described, indicating the leading species of the different cornmunities studied