RESUMO
Rhodopsin, the light-sensitive visual pigment expressed in rod photoreceptors, is specialized for vision in dim-light environments. Aquatic environments are particularly challenging for vision due to the spectrally dependent attenuation of light, which can differ greatly in marine and freshwater systems. Among fish lineages that have successfully colonized freshwater habitats from ancestrally marine environments, croakers are known as highly visual benthic predators. In this study, we isolate rhodopsins from a diversity of freshwater and marine croakers and find that strong positive selection in rhodopsin is associated with a marine to freshwater transition in South American croakers. In order to determine if this is accompanied by significant shifts in visual abilities, we resurrected ancestral rhodopsin sequences and tested the experimental properties of ancestral pigments bracketing this transition using in vitro spectroscopic assays. We found the ancestral freshwater croaker rhodopsin is redshifted relative to its marine ancestor, with mutations that recapitulate ancestral amino acid changes along this transitional branch resulting in faster kinetics that are likely to be associated with more rapid dark adaptation. This could be advantageous in freshwater due to the redshifted spectrum and relatively narrow interface and frequent transitions between bright and dim-light environments. This study is the first to experimentally demonstrate that positively selected substitutions in ancestral visual pigments alter protein function to freshwater visual environments following a transition from an ancestrally marine state and provides insight into the molecular mechanisms underlying some of the physiological changes associated with this major habitat transition.
Assuntos
Adaptação Biológica/genética , Perciformes/genética , Rodopsina/genética , Seleção Genética , Visão Ocular/genética , Animais , Água Doce , Perciformes/metabolismo , Rodopsina/metabolismo , América do SulRESUMO
Cichlids encompass one of the most diverse groups of fishes in South and Central America, and show extensive variation in life history, morphology, and colouration. While studies of visual system evolution in cichlids have focussed largely on the African rift lake species flocks, Neotropical cichlids offer a unique opportunity to investigate visual system evolution at broader temporal and geographic scales. South American cichlid colonization of Central America has likely promoted accelerated rates of morphological evolution in Central American lineages as they encountered reduced competition, renewed ecological opportunity, and novel aquatic habitats. To investigate whether such transitions have influenced molecular evolution of vision in Central American cichlids, we sequenced the dim-light rhodopsin gene in 101 Neotropical cichlid species, spanning the diversity of the clade. We find strong evidence for increased rates of evolution in Central American cichlid rhodopsin relative to South American lineages, and identify several sites under positive selection in rhodopsin that likely contribute to adaptation to different photic environments. We expressed a Neotropical cichlid rhodopsin protein invitro for the first time, and found that while its spectral tuning properties were characteristic of typical vertebrate rhodopsin pigments, the rate of decay of its active signalling form was much slower, consistent with dim light adaptation in other vertebrate rhodopsins. Using site-directed mutagenesis combined with spectroscopic assays, we found that a key amino acid substitution present in some Central American cichlids accelerates the rate of decay of active rhodopsin, which may mediate adaptation to clear water habitats.
Assuntos
Ciclídeos/genética , Adaptação à Escuridão/genética , Rodopsina/genética , Animais , Evolução Biológica , América Central , Ecossistema , Evolução Molecular , Proteínas do Olho/genética , Variação Genética/genética , Lagos , Luz , Mutagênese Sítio-Dirigida , FilogeniaRESUMO
High-altitude environments present a range of biochemical and physiological challenges for organisms through decreases in oxygen, pressure, and temperature relative to lowland habitats. Protein-level adaptations to hypoxic high-altitude conditions have been identified in multiple terrestrial endotherms; however, comparable adaptations in aquatic ectotherms, such as fishes, have not been as extensively characterized. In enzyme proteins, cold adaptation is attained through functional trade-offs between stability and activity, often mediated by substitutions outside the active site. Little is known whether signaling proteins [e.g., G protein-coupled receptors (GPCRs)] exhibit natural variation in response to cold temperatures. Rhodopsin (RH1), the temperature-sensitive visual pigment mediating dim-light vision, offers an opportunity to enhance our understanding of thermal adaptation in a model GPCR. Here, we investigate the evolution of rhodopsin function in an Andean mountain catfish system spanning a range of elevations. Using molecular evolutionary analyses and site-directed mutagenesis experiments, we provide evidence for cold adaptation in RH1. We find that unique amino acid substitutions occur at sites under positive selection in high-altitude catfishes, located at opposite ends of the RH1 intramolecular hydrogen-bonding network. Natural high-altitude variants introduced into these sites via mutagenesis have limited effects on spectral tuning, yet decrease the stability of dark-state and light-activated rhodopsin, accelerating the decay of ligand-bound forms. As found in cold-adapted enzymes, this phenotype likely compensates for a cold-induced decrease in kinetic rates-properties of rhodopsin that mediate rod sensitivity and visual performance. Our results support a role for natural variation in enhancing the performance of GPCRs in response to cold temperatures.
Assuntos
Altitude , Rodopsina/química , Animais , Teorema de Bayes , Evolução Biológica , Bolívia , Peixes-Gato , Proteínas e Peptídeos de Choque Frio/química , Temperatura Baixa , Cristalografia por Raios X , Equador , Evolução Molecular , Geografia , Células HEK293 , Humanos , Cinética , Mutação , Peru , FilogeniaRESUMO
Programming of hypothalamic functions regulating energy homeostasis may play a role in intrauterine growth restriction (IUGR)-induced adulthood obesity. The present study investigated the effects of IUGR on the hypothalamus proteome and metabolome of adult rats submitted to 50% protein-energy restriction throughout pregnancy. Proteomic and metabolomic analyzes were performed by data independent acquisition mass spectrometry and multiple reaction monitoring, respectively. At age 4 months, the restricted rats showed elevated adiposity, increased leptin and signs of insulin resistance. 1356 proteins were identified and 348 quantified while 127 metabolites were quantified. The restricted hypothalamus showed down-regulation of 36 proteins and 5 metabolites and up-regulation of 21 proteins and 9 metabolites. Integrated pathway analysis of the proteomics and metabolomics data indicated impairment of hypothalamic glucose metabolism, increased flux through the hexosamine pathway, deregulation of TCA cycle and the respiratory chain, and alterations in glutathione metabolism. The data suggest IUGR modulation of energy metabolism and redox homeostasis in the hypothalamus of male adult rats. The present results indicated deleterious consequences of IUGR on hypothalamic pathways involved in pivotal physiological functions. These results provide guidance for future mechanistic studies assessing the role of intrauterine malnutrition in the development of metabolic diseases later in life.
Assuntos
Retardo do Crescimento Fetal/metabolismo , Metabolômica , Obesidade/metabolismo , Biossíntese de Proteínas/genética , Proteômica , Animais , Animais Recém-Nascidos , Metabolismo Energético/genética , Feminino , Retardo do Crescimento Fetal/genética , Hipotálamo/metabolismo , Obesidade/genética , Obesidade/patologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , RatosRESUMO
The National Consense abot Spasticity by Brazilian Society of Physical Medicine and Rehabilitation (SBMFR) and Brazilian Medical Association (AMB) was done based on critical analysis of epidemiological studies, showing that traditional terapeutic resources need more studies for posterior approving
Assuntos
Espasticidade MuscularRESUMO
Acquired arachnoid cysts of the spinal cord are uncommon causes of spinal cord compression in the pediatric group. Meningitis, trauma and hemorrhage are considered to be causative or contributing factors. Interestingly, no spinal arachnoid cysts have been reported in patients after subarachnoid hemorrhage or meningitis, conditions expected to cause arachnoid scarring. We describe a child of 1 year and 10 months with thoracic spine trauma with crural paraplegia and anesthesia at level T5 submitted to serial magnetic resonance imagery at 5 days and 18 months, after trauma showing evolution from subarachnoid hemorrhage and adhesions of the arachnoid space to a posterior hypertensive thoracic intradural arachnoid cyst.
Assuntos
Cistos Aracnóideos/etiologia , Hemorragia/etiologia , Imageamento por Ressonância Magnética , Doenças da Coluna Vertebral/etiologia , Traumatismos da Coluna Vertebral/complicações , Cistos Aracnóideos/diagnóstico , Dura-Máter , Hemorragia/diagnóstico , Humanos , Lactente , Masculino , Paraplegia/complicações , Doenças da Coluna Vertebral/diagnóstico , Traumatismos da Coluna Vertebral/diagnósticoRESUMO
Faz-se a analise de cinco casos de doentes mentais submetidos a hipotalamotomia posterior estereotaxica no Servico de Neurocirurgia do Prof. Gianni Temponi do INDC-UFRJ, desde 1981 ate meados de 1983. Uma pequena analise da fisiologia do hipotalamo e do sistema nervoso autonomo e feita, a titulo de inroducao.
Assuntos
Hipotálamo Posterior , Cirurgia Geral , Neurocirurgia , Sistema Límbico , Hipotálamo Posterior , Cirurgia Geral , Neurocirurgia , Sistema LímbicoRESUMO
O presente trabalho considera o diabetes insipidus central em seus aspectos etiopatogenicos e fisiopatologicos, enfatiza o quadro sintomatologico classico e os testes diagnosticos empregados na afeccao e finalmente destaca os mais recentes avancos no terreno terapeutico a luz de 13 pacientes portadores da condicao, acompanhados pelos autores.
Assuntos
Diabetes Mellitus , Diabetes Insípido , Diagnóstico , Diabetes Mellitus , Diabetes Insípido , DiagnósticoRESUMO
A sindrome da sela vazia tem despertado grande interesse nao so dos neurocirurgioes e neurologistas como tambem dos endocrinologistas. Os autores fazem a analise do seu material, constituido de dez casos, num periodo de tres anos, investigados nos servicos de Neurocirurgia da Universidade Federal do Rio de Janeiro, chamando atencao para os seus principais aspectos, a luz dos conhecimentos atuais.
Assuntos
Neurocirurgia , Síndrome da Sela Vazia , Neurocirurgia , Síndrome da Sela VaziaRESUMO
O presente trabalho comenta e relata 11 casos de hematomas intracerebrais espontaneos, principalmente do ponto de vista terapeutico, mostrando o problema que estes hematomas intracerebrais colocam ao neurologista e neurocirurgiao.
Assuntos
Hematoma , Doenças do Sistema Nervoso , Hematoma , Doenças do Sistema NervosoRESUMO
Os autores apresentam tres casos vistos no Servico de Neurocirurgia do INDC-UFRJ a partir de 1982. O diagnostico diferencial entre cisto e pseudocisto, no que respeita a sua localizacao intracraniana, e de primordial importancia com vistas ao tratamento a ser efetuado. Dois destes casos foram considerados pseudocistos e o cisto foram submetidos a tratamento cirurgico e sao tecidos comentarios a respeito. E relevada a importancia da cintilografia do espaco subaracnoideo para o diagnostico correto nesses casos.