219 research outputs found
Carrion Availability in Space and Time
Introduction
Availability of carrion to scavengers is a central issue in carrion ecology and management, and is crucial for understanding the evolution of scavenging behaviour. Compared to live animals, their carcasses are relatively unpredictable in space and time in natural conditions, with a few exceptions (see below, especially Sect. “Carrion Exchange at the Terrestrial-Aquatic Interface”). Carrion is also an ephemeral food resource due to the action of a plethora of consumers, from microorganisms to large vertebrates, as well as to desiccation (i.e., loss of water content; DeVault et al. 2003; Beasley et al. 2012; Barton et al. 2013; Moleón et al. 2014). With a focus on vertebrate carcasses, here we give an overview of (a) the causes that produce carrion, (b) the rate of carrion production, (c) the factors affecting carrion quality, and (d) the distribution of carrion in space and time, both in terrestrial and aquatic environments (including their interface). In this chapter, we will focus on naturally produced carrion, whereas non-natural causes of animal mortality are described in chapter “Human-Mediated Carrion: Effects on Ecological Processes”. However, throughout this chapter we also refer to extensive livestock carrion, because in the absence of strong restrictions such as those imposed in the European Community after the bovine spongiform encephalopathy crisis (Donázar et al. 2009; Margalida et al. 2010), the spatiotemporal availability of carrion of extensive livestock and wild ungulates is similar
Correcting for enzyme immunoassay changes in long term monitoring studies
Enzyme immunoassays (EIAs) are a common tool for measuring steroid hormones in wildlife due to their low cost, commercial availability, and rapid results. Testing technologies improve continuously, sometimes requiring changes in protocols or crucial assay components. Antibody replacement between EIA kits can cause differences in EIA sensitivity, which can hinder monitoring hormone concentration over time. The antibody in a common cortisol EIA kit used for long-term monitoring of stress in wildlife was replaced in 2014, causing differences in cross reactivity and standard curve concentrations. Therefore, the objective of this study was to develop a method to standardize results following changes in EIA sensitivity. We validated this method using cortisol concentrations measured in the hair of brown bears (Ursus arctos). • We used a simple linear regression to model the relationship between cortisol concentrations using kit 1 and kit 2. • We found a linear relationship between the two kits (R2 = 0.85) and used the regression equation (kit2 = (0.98 × kit1) + 1.65) to predict cortisol concentrations in re-measured samples. • Mean predicted percent error was 16% and 72% of samples had a predicted percent error <20%, suggesting that this method is well-suited for correcting changes in EIA sensitivity.publishedVersio
Potential Role of Tumor Necrosis Factor-α in Downregulating Sex Hormone-Binding Globulin
Altres ajuts:D.M.S. received a grant from the Instituto de Salud Carlos III and is the recipient of a Miguel Servet contract. This work is supported by Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM). CIBERDEM is an initiative of Instituto de Salud Carlos III.Low plasma sex hormone-binding globulin (SHBG) levels are associated with obesity and predict the development of type 2 diabetes. The reason why obese individuals have low circulating SHBG has been attributed to hyperinsulinemia, but no mechanistic evidence has been described. The aim of the current study is to explore whether tumor necrosis factor-α (TNF-α) rather than insulin could be the main factor accounting for low SHBG levels in obesity. We performed in vitro and in vivo studies using human HepG2 cells and human SHBG transgenic mice. In addition, a cross-sectional study to explore the relationship between TNF-α and SHBG in obese patients and an interventional study to examine the effect of insulin administration on circulating SHBG in type 2 diabetic patients were performed. We provide evidence that TNF-α, but not insulin, is the main factor by which SHBG is reduced in obesity. Plasma SHBG was significantly increased rather than decreased after insulin treatment in diabetic patients. TNF-α-induced reduction of SHBG expression was mediated by downregulating HNF4A. Finally, a negative and independent correlation was found between plasma TNF-α receptor 1 and SHBG levels in obese patients. Our results suggest that TNF-α plays an important role downregulating SHBG in chronic low-grade inflammatory diseases such as obesity and type 2 diabetes
Aprendizaje basado en proyectos (PBL) aplicado a la docencia de sistemas tecnológicos de última generación
El planteamiento general de la docencia de asignaturas cuyo contenido es eminentemente tecnológico, presenta el reto del constante y rápido cambio asociado a los avances en desarrollo tecnológico. Dentro de este contexto, se plantea emplear un método basado en la generación de herramientas que permitan un seguimiento autónomo de los cambios frente a opciones más descriptivas del estado actual de los sistemas estudiados. Sobre esta base, se estudia la idoneidad de un contexto basado en el desarrollo de proyectos que, si bien tienen necesariamente que abordar una temática particular, supone una forma a priori interesante de generar las habilidades necesarias para el aprendizaje autónomo y continuado
Screening of virulence genes in Staphylococcus aureus isolates from rabbits
Staphylococcus aureus is a versatile pathogen that can survive in diverse host environments and produce a wide range of diseases both in humans and animals. This versatility depends on its ability to modulate gene expression and the synthesis of virulence determinants. Therefore, this study aimed to investigate the distribution of bacterial virulence determinants in the most prevalent S. aureus strain types causing lesions in rabbits. Sixty-nine S. aureus strains were isolated from rabbit does with
different chronic purulent lesions from 30 Spanish industrial rabbitries. Genotyping characterization of the strains was performed based on the analysis of the polymorphic regions of the coa, spa and clfB genes, as well as Multylocus Sequence Typing (MLST) on one strain of each of the most frequent genotypes. The isolates were also analyzed for the presence of forty virulence genes by PCRs and Southern blot, in order to determine their relationship with the genotype and the type of infection respectively. The great majority of isolates belonging to the same genotype were related to the same virulence factors, even though certain virulence factors were variable inside a genotype. However, the type of infection could not be related to any combination of virulence factors
Acció dels andrògens en el testicle: un paper per a la meiosi
La funció que duen a terme els andrògens en l'espermatogènesi és, encara en certa mesura,
enigmàtica: mentre que llur implicació és absolutament vital en la iniciació i en el manteniment
del procés espermatogènic normal, la seva funció específica encara no està definida de
manera precisa. Els andrògens, com les altres hormones esteroïdals, actuen a través del seu
corresponent receptor anomenat receptor d'andrògens (AR). Fins avui, no hi ha gaire evidència
que recolzi l'existència de diverses isoformes de l'AR com en el cas del sistema estrògensreceptor
d'estrògens. Per tant, la pregunta de com els andrògens duen a terme la seva acció
en l'espermatogènesi s'ha d'abordar definint dos processos: en primer lloc, s'han d'identifi-
car amb total certesa els tipus cell. ulars testiculars capaços de respondre directament a l'estimulació
androgènica. De manera específica, la qüestió per resoldre és quins són els tipus cellulars
que expressen l'AR en el testicle. En segon lloc, sabent també que el complex del lligand
unit a l'AR actua com a factor de transcripció, caldrà determinar quins són els gens que
estaran activats o reprimits en les cèll. ules que tenen AR en resposta a l'estimulació androgènica.
Fins que aquestes dues preguntes no estiguin contestades amb tota certesa, el mecanisme
pel qual els andrògens regulen l'espermatogènesi serà, en el millor dels casos, especulatiu.
En aquesta revisió presentem evidència que els andrògens actuen únicament a les cèll. ules
somàtiques del testicle, com són les cèll. ules de Sertoli, les de Leydig, les mioides peritubulars
i les cèll. ules del múscul llis que envolten els vasos sanguinis. A més a més, també discutim
la possibilitat que els andrògens siguin indispensables per a l'inici de la meiosi, encara que continua essent desconegut el mecanisme pel qual els andrògens actuen en aquest procés.The role that androgens play in spermatogenesis still remains enigmatic: whereas their involvement
is absolutely vital to the initiation and maintenance of the normal spermatogenic
process, their specific role is yet to be defined. Androgens, like other steroid hormones, act via
their corresponding receptor termed the androgen receptor (AR). To date, there is little evidence
to support the notion that there are multiple forms of AR as is the case for the estrogen-estrogen
receptor system. Thus, the question of how androgens manifest their action on spermatogenesis
becomes one of defining two processes: First, the cell types within the testis that are capable of
responding directly to androgen stimulation must be identified with absolute certainty. Specifically,
this question can be stated as what cell types in the testis express AR. Second, given that
the ligand-bound AR serves as a transcription factor, the question then becomes what are the
genes turned on or off in AR positive cells in response to androgen stimulation? Until these two
questions are unequivocally answered, the mechanism of how androgens regulate spermatogenesis
will remain speculative at best. In this review we present evidence that androgens act
solely at the level of the somatic cells of the testis, including Sertoli cells, Leydig cells, peritubular
myoid cells and smooth muscle cells surrounding blood vessels. In addition, we discuss
the likely possibility that androgens are indispensable for the onset of meiosis, albeit how they
accomplish this remains a mystery
Level of hamstrings damage depending on force-generating capacity and creatine kinase activity
The aim of the present study was to categorize the eccentric exercise-induced
hamstrings damage by using easy measurable markers such as force-generating
capacity and serum
creatine
kinase activityPeer ReviewedPostprint (published version
Shifting markers of identity in East London's diasporic religious spaces
This article discusses the historical and geographical contexts of diasporic religious buildings in East London, revealing – contrary both to conventional narratives of immigrant integration, mobility, and succession and to identitarian understandings of belonging – that in such spaces and in the concrete devotional practices enacted in them, markers and boundaries of identity (ritual, spatial, and political) are contested, renegotiated, erased, and rewritten. It draws on a series of case-studies: Fieldgate Street Synagogue in its interrelationship with the East London Mosque; St Antony's Catholic Church in Forest Gate where Hindus and Christians worship together; and the intertwined histories of Methodism and Anglicanism in Bow Road. Exploration of the intersections between ethnicity, religiosity, and class illuminates the ambiguity and instability of identity-formation and expression within East London's diasporic faith spaces
Señales, sistemas y telecomunicación
En ingeniería de telecomunicación los conceptos relacionados con teoría de la señal son uno de los pilares básicos. Si bien, la teoría no es excesivamente compleja, su asimilación no resulta sencilla. Los métodos empleados para el proceso de optimización de sistemas de refuerzo sonoro suponen una aplicación práctica directa de estos conceptos, con un impacto visual inmediato. Se pretende evaluar el impacto en el proceso de interiorización de los conceptos de teoría de la señal (principalmente respuesta al impulso y función de transferencia) de la aplicación de los procesos de análisis y optimización de sistemas de refuerzo sonoro
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