Mechanisms for the Evolution of a Derived Function in the Ancestral Glucocorticoid Receptor

Understanding the genetic, structural, and biophysical mechanisms that caused protein functions to evolve is a central goal of molecular evolutionary studies. Ancestral sequence reconstruction (ASR) offers an experimental approach to these questions. Here we use ASR to shed light on the earliest functions and evolution of the glucocorticoid receptor (GR), a steroid-activated transcription factor that plays a key role in the regulation of vertebrate physiology. Prior work showed that GR and its paralog, the mineralocorticoid receptor (MR), duplicated from a common ancestor roughly 450 million years ago; the ancestral functions were largely conserved in the MR lineage, but the functions of GRs—reduced sensitivity to all hormones and increased selectivity for glucocorticoids—are derived. Although the mechanisms for the evolution of glucocorticoid specificity have been identified, how reduced sensitivity evolved has not yet been studied. Here we report on the reconstruction of the deepest ancestor in the GR lineage (AncGR1) and demonstrate that GR's reduced sensitivity evolved before the acquisition of restricted hormone specificity, shortly after the GR–MR split. Using site-directed mutagenesis, X-ray crystallography, and computational analyses of protein stability to recapitulate and determine the effects of historical mutations, we show that AncGR1's reduced ligand sensitivity evolved primarily due to three key substitutions. Two large-effect mutations weakened hydrogen bonds and van der Waals interactions within the ancestral protein, reducing its stability. The degenerative effect of these two mutations is extremely strong, but a third permissive substitution, which has no apparent effect on function in the ancestral background and is likely to have occurred first, buffered the effects of the destabilizing mutations. Taken together, our results highlight the potentially creative role of substitutions that partially degrade protein structure and function and reinforce the importance of permissive mutations in protein evolution

Abundance and Distribution of Sharks in Northeast Florida Waters and Identification of Potential Nursery Habitat

Sharks are considered top predators in many marine ecosystems and can play an important role in structuring community ecology. As a result, it is necessary to understand the factors that influence their abundance and distribution. This is particularly important as fishery managers develop management plans for sharks that identify areas that serve as essential fish habitat, especially nursery habitat. However, our understanding of shark habitat use in northeast Florida waters is limited. The goal of this study was to characterize the abundance and distribution of sharks in northeast Florida estuaries and to examine the effect of abiotic factors on shark habitat use. A bottom longline survey conducted from 2009 to 2011 indicated that 11 shark species use the estuarine waters of northeast Florida during the summer months. Atlantic Sharpnose Sharks Rhizoprionodon terraenovae, Blacktip Sharks Carcharhinus limbatus, and Bonnetheads Sphyrna tiburo were the most abundant species and made up 81.4% of the total catch. Site, month, and bottom water temperature were the most important factors determining the presence and abundance of sharks and suggest both regional and seasonal variations in the use of northeast Florida waters. Depth, salinity, and dissolved oxygen were also important factors. Our data show that these waters serve as a nursery for Atlantic Sharpnose and Blacktip Sharks, with young-of-the-year and juveniles being present in the summer months. Limited tag-return data reveal that juvenile sharks remain in these waters throughout the summer and that some return in subsequent summers. This is the first study to characterize the abundance and distribution of sharks and identify potential nursery areas in northeast Florida estuaries. Received October 10, 2012; accepted March 7, 2013. © 2013 Copyright Taylor and Francis Group, LLC

Assessment of Exposure to Cytochrome P4501a1-Inducing Pollutants in Pelagic Fishes from the Western North Atlantic and Gulf of Mexico Through Analysis of Liver EROD Activity

We examined liver samples taken from pelagic fishes captured in the western North Atlantic and Gulf of Mexico for evidence of exposure to cytochrome P4501a1 (Cyp1a1)-inducing pollutants, such as polycyclic aromatic hydrocarbon (PAHs), polychlorinated biphenyls (PCBs), and polychlorinated dibenzodioxins (PCDDs). A key purpose of this research was to determine if pelagic fish populations in the northeast Gulf of Mexico are exhibiting physiological effects associated with exposure to PAHs from the Deepwater Horizon Oil Spill. Exposure to Cyp1a1-inducing contaminants was determined through measurements of ethoxyresorufin-O-deethylase (EROD) activity in fish livers. Samples obtained from the Atlantic Ocean provided a comparison for those taken from the oil exposed portions of the Gulf of Mexico. Our preliminary results show low levels of EROD activity in teleosts and elasmobranchscaptured from both sampling areas. These data suggest low impact of PAHs in pelagic fishes potentially exposed to oil spill waters

Educação Física e sociedade de consumo

O artigo em questão busca refletir acerca da influência da sociedade de consumo na educação, principalmente na educação física, e para isso, resgata a Educação Física através dos tempos, sua criação e sua posterior constituição e inclusão como disciplina, sua formação burguesa de caráter discriminador que apesar de nos tempos mais remotos ser apenas um ritual aos deuses, com a criação da competição, acabou segregando os elementos da sociedade, pois apenas os mais perfeitos, eram considerados mais capazes. Como de forma menos acentuada, nos dias atuais esses preceitos ainda são disseminados. Assim propõe-se fazer uma análise, de como as representações de "um modelo ideal" de corpo, conduta social e estereótipos estão presentes nessas aulas, como a sociedade tem influenciado no comportamento dos indivíduos, transformando-os em produtos de uma linha de produção onde não pode haver falhas na sua composição, e se alguém foge desses padrões, acaba ou sendo excluído da sociedade, ou colocado em evidência por sua exoticidade. Também alertando sobre como tem-se relacionado atividade física com saúde, sem se preocupar com os males que a primeira pode causar sem a devida manutenção da segunda. Qualidade de vida é pressuposto básico de cidadania, mas os atuais professores de educação física tem tido dificuldades para levar esse conceito para dentro de uma sala da aula. Com a atual massificação da sociedade, fica difícil evitar que a educação física siga o mesmo rumo, se tornando mais um mecanismo da massificação

Shark tooth collagen stable isotopes (δ\u3csup\u3e15\u3c/sup\u3eN and δ\u3csup\u3e13\u3c/sup\u3eC) as ecological proxies

The isotopic composition of tooth-bound collagen has long been used to reconstruct dietary patterns of animals in extant and palaeoecological systems. For sharks that replace teeth rapidly in a conveyor-like system, stable isotopes of tooth collagen (δ13CTeeth & δ15NTeeth) are poorly understood and lacking in ecological context relative to other non-lethally sampled tissues. This tissue holds promise, because shark jaws may preserve isotopic chronologies from which to infer individual-level ecological patterns across a range of temporal resolutions. Carbon and nitrogen stable isotope values were measured and compared between extracted tooth collagen and four other non-lethally sampled tissues of varying isotopic turnover rates: blood plasma, red blood cells, fin and muscle, from eight species of sharks. Individual-level isotopic variability of shark tooth collagen was evaluated by profiling teeth of different ages across whole jaws for the shortfin mako shark Isurus oxyrinchus and sandbar shark Carcharhinus plumbeus. Measurements of δ13CTeeth and δ15NTeeth were positively correlated with isotopic values from the four other tissues. Collagen δ13C was consistently 13C-enriched relative to all other tissues. Patterns for δ15N were slightly less uniform; tooth collagen was generally 15N-enriched relative to muscle and red blood cells, but congruent with fin and blood plasma (values clustered around a 1:1 relationship). Significant within-individual variability was observed across whole shortfin mako shark (δ13C range = 1.4‰, δ15N range = 3.6‰) and sandbar shark (δ13C range = 1.2‰–2.4‰, δ15N range = 1.7‰–2.4‰) jaws, which trended with tooth age. We conclude that amino acid composition and associated patterns of isotopic fractionation result in predictable isotopic offsets between tissues. Within-individual variability of tooth collagen stable isotope values suggests teeth of different ages may serve as ecological chronologies, that could be applied to studies on migration and individual-level diet variation across diverse time-scales. Greater understanding of tooth replacement rates, isotopic turnover and associated fractionation of tooth collagen will help refine potential ecological inferences, outlining clear goals for future scientific inquiry

Extração e caracterização de carboidratos presentes no alho (Allium sativum L.): proposta de metodologia alternativa

O alho é um alimento funcional que contém inulina, um polissacarídeo de reserva, que auxilia no controle das bactérias patogênicas e putrefativas existentes no intestino. O presente trabalho teve por objetivo avaliar uma metodologia simples de extração de carboidratos do alho, qualificar e quantificar a composição desse extrato empregando a cromatografia líquida de alta eficiência e a espectroscopia na região do infravermelho utilizando para isso um padrão de inulina. Os bulbos de alho foram submetidos à extração aquosa a quente por 4 horas; posteriormente o líquido resultante foi separado e a ele foram adicionados 300 mL de acetona. O extrato isolado foi avaliado quanto aos seus produtos de hidrólise alcalina e os resultados indicaram a presença de um oligossacarídeo como o observado para a inulina padrão. As principais bandas características dos carboidratos foram visualizadas entre 3600 a 3000 e 1200 a 900 cm-1. A técnica utilizada neste trabalho pode ser utilizada para extração da inulina, pois agrega valor a produtos naturais, gerando alternativas do ponto de vista econômico

Reproduction estrategies

Elasmobranchs are an evolutionarily conserved group that has success- fully survived for over 400 million years. The permanence of elasmobranch populations has largely depended on the reproductive strategies of the population, as the primary requirement for successful propagation of any species and their individuals is the ability to reproduce. In vertebrates, reproductive strategies are regulated by the brain-gonadal axis, which controls the synthesis of reproductive hormones triggering all aspects related to reproduction. This chapter details the different reproductive strategies employed by elasmobranchs, from the wider range of reproductive modes including oviparity (egg-laying) and different forms of viviparity (live- bearing); followed by a description of the different reproductive cycles, from seasonal to continuous, displayed by both sexes. Finally, the role of reproductive hormones in both females and males regulating gametogenesis and the different reproductive cycles are discussed. The endocrine control of the elasmobranch reproductive strategies are preserved throughout vertebrate evolution, however they are distinct within this group.Fil: Awruch, Cynthia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin