914 resultados para morphological adaptation
Resumo:
The rate of food consumption is a major factor affecting success in scramble competition for a limited amount of easy-to-find food. Accordingly, several studies report positive genetic correlations between larval competitive ability and feeding rate in Drosophila; both become enhanced in populations evolving under larval crowding. Here, we report the experimental evolution of enhanced competitive ability in populations of D. melanogaster previously maintained for 84 generations at low density on an extremely poor larval food. In contrast to previous studies, greater competitive ability was not associated with the evolution of higher feeding rate; if anything, the correlation between the two traits across lines tended to be negative. Thus, enhanced competitive ability may be favored by nutritional stress even when competition is not intense, and competitive ability may be decoupled from the rate of food consumption.
Resumo:
This work was conducted at the Universidade Estadual de Londrina (UEL), in Londrina, State of Paraná, Brazil, with the goal to study food-type soybean (Glycine max (L.) Merrill) genotypes performance for use in cultivation or crosses. A total of 104 genotypes were analyzed: 88 were food-type with large seeds, eight were food-type with small seeds, and eight-grain types adapted cultivars. The experimental plan was in randomized complete block design with four replications, and 12 traits of agronomic importance were considered. Genetic diversity was observed in the food-type germplasm. There were some genotypes with high yield adapted to a normal period of sowing. Soybean genetic improvement programs for direct human consumption in Brazil, either by means of Asiatic pure lines or by means of the incorporation of genes for late flowering in short-day conditions in this lines is highly viable.
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Light adaptation is crucial for coping with the varying levels of ambient light. Using high-density electroencephalography (EEG), we investigated how adaptation to light of different colors affects brain responsiveness. In a within-subject design, sixteen young participants were adapted first to dim white light and then to blue, green, red, or white bright light (one color per session in a randomized order). Immediately after both dim and bright light adaptation, we presented brief light pulses and recorded event-related potentials (ERPs). We analyzed ERP response strengths and brain topographies and determined the underlying sources using electrical source imaging. Between 150 and 261ms after stimulus onset, the global field power (GFP) was higher after dim than bright light adaptation. This effect was most pronounced with red light and localized in the frontal lobe, the fusiform gyrus, the occipital lobe and the cerebellum. After bright light adaptation, within the first 100ms after light onset, stronger responses were found than after dim light adaptation for all colors except for red light. Differences between conditions were localized in the frontal lobe, the cingulate gyrus, and the cerebellum. These results indicate that very short-term EEG brain responses are influenced by prior light adaptation and the spectral quality of the light stimulus. We show that the early EEG responses are differently affected by adaptation to different colors of light which may contribute to known differences in performance and reaction times in cognitive tests.
Resumo:
Based on the experience of the Maria Montessori Teaching Resources Center in Alghero, the Algherese adaptation of 'Tintín al país de l'or negre' (Barcelona, 1995), coordinated by the author of the present article, constitues one of the most successful publications in terms of the creation and utilization of a useful Algherese language model for schoools. On the basis of criteria presented in the paper 'L'ensenyament del català a l'Alguer i la qüestió del model de llengua' at a meeting of the Philological Section of the Institut d'Estudis Catalans in 2000, the model employed applies Catalan spelling standards but, at the same time, is in greater alignment with the Catalan spoken in Alghero from a morphological, lexical and syntactic point of view. the article reflects upon two possible methods of codification, e.g. of Algherese, put forward by the sociolinguist Enrico Chessa who in the process regarded the disparities and differences between spelling and phonetic transcription.
Resumo:
Tumour cells proliferate much faster than normal cells; nearly all anticancer treatments are toxic to both cell types, limiting their efficacy. The altered metabolism resulting from cellular transformation and cancer progression supports cellular proliferation and survival, but leaves cancer cells dependent on a continuous supply of energy and nutrients. Hence, many metabolic enzymes have become targets for new cancer therapies. In addition to its well-described roles in cell-cycle progression and cancer, the cyclin/CDK-pRB-E2F1 pathway contributes to lipid synthesis, glucose production, insulin secretion, and glycolytic metabolism, with strong effects on overall metabolism. Notably, these cell-cycle regulators trigger the adaptive "metabolic switch" that underlies proliferation.
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The genus Hylomys was thought to be represented by a single widespread species. Biochemical and morphometric analyses of several Southeast Asian populations reveal that Sumatra is inhabited by two distinct species, the dwarf gymnure (H. parvus) and the lesser gymnure (H. suillus). The absence of interbreeding between these two groups along with their relatively ancient common origins are documented by several diagnostic loci and a large Nei's genetic distance (D = 0.353 +/- 0.035). The dwarf gymnure has been reported only from the slopes of the Mt. Kerinci volcano in Sumatra, where the species lives at higher elevations than its potential competitor, the lesser gymnure. Other populations of Hylomys from Java, Borneo, and Malaysia are more closely related to the Sumatran sample of H. suillus, but they exhibit strong interpopulational genetic differentiation (D = 0.165 +/- 0.040) that may be accounted for by their isolated montane habitat. In addition, a principal-components analysis based on 16 measurements of the skull clearly separates adult specimens of both species. There is little overlap in the measurements between H. suillus (which is larger) and H. parvus. On Sumatra where both species may be sympatric, the notched space between premaxillary tips, soft texture of the fur, and more delicate skull and dentition are diagnostic of H. parvus.
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The physiological and morphological responses of the forage grasses Brachiaria brizantha cv. Marandu, B. decumbens and B. humidicola were compared for plants grown in pots under flooding and well-drained conditions for 14 days. Flooding reduced specific leaf area and biomass allocation to roots in all species and enhanced leaf senescence in B. brizantha and B. decumbens. Relative growth rate was reduced by flooding in B. brizantha and B. decumbens, but not in B. humidicola.Leaf elongation rate was unaffected by flooding in B. decumbens and B. humidicola, but declined in B. brizantha since the first day of flooding. Net photosynthesis and leaf chlorophyll content were reduced by flooding in B. brizantha; however, no flooding effect could be detected in the other two species. For all species, there was a close relationship between net photosynthesis and stomatal conductance under flooding. These results show that the studied species have distinct degrees of tolerance to flood, B. brizantha is intolerant, B. decumbens is moderately tolerant and B. humidicola is tolerant. Because leaf elongation rate was immediately depressed by flooding only in B. brizantha, this measurement could be appropriate as an early detection mechanism for relative flood tolerance in Brachiaria spp.
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About 30 million people live above 2500 m in the Andean Mountains of South America. Among them are 5.5 million Aymaras, an ethnic group with its own language, living on the altiplano of Bolivia, Peru, and northern Chile at altitudes of up to 4400 m. In this high altitude region traces of human population go back for more than 2000 years with constant evolutionary pressure on its residents for genetic adaptation to high altitude. Aymaras as the assumed direct descendents of the ancient cultures living in this region were the focus of much research interest during the last decades and several distinctive adaptation patterns to life at high altitude have been described in this ethnic group. The aim of this article was to review the physiology and pathophysiology of circulatory adaptation and maladaptation to longtime altitude exposure in Aymaras and Caucasians.
Resumo:
L'importance des proches et le rôle primordial des relations familiales pour l'adaptation et l'ajustement psychologique des individus sont largement reconnus. Cependant, peu d'études ont considéré que, dans la modernité avancée, les réseaux de proches ou familiaux sont diversifiés, caractérisés par des interdépendances complexes. La littérature sur les relations interpersonnelles et l'adaptation a négligé cette diversité et omis que les interdépendances structurales, de soutien mais aussi de conflit, pouvaient s'avérer importantes à considérer en regard de l'adaptation et de l'ajustement psychologique des individus. La présente thèse apporte des éléments de compréhension sur le lien entre les configurations de proches et l'adaptation individuelle dans le parcours de vie, en se centrant sur des individus en situation de vulnérabilité, que ce soit parce qu'ils font l'expérience d'une transition importante de leur parcours, ou en raison d'un manque de ressources psychologiques, cognitives et/ou sociales. Des résultats empiriques éclairent quatre grands axes de questionnement portant sur les ressources et le stress présents dans les interdépendances au sein des configurations familiales et de proches, sur leur association avec l'ajustement psychologique des individus, sur leur évolution au cours du temps, ainsi que sur la façon dont ces interdépendances sont façonnées par les trajectoires de vie. Les résultats mettent en évidence une diversité de configurations familiales ou de proches, qui donne lieu à des degrés inégaux de ressources, significativement associées à l'ajustement psychologique. Cependant, les interdépendances au sein des configurations ne constituent que rarement des ressources ou un facteur protecteur pour les individus en situation de vulnérabilité mais, au contraire, elles génèrent du stress supplémentaire. L'exploration longitudinale met en évidence une importante instabilité dans les configurations familiales et de proches des individus en situation de vulnérabilité qui compromet leur adaptation et leur ajustement psychologique.
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Spherical carbon coated iron particles of nanometric diameter in the 510 nm range have been produced by arc discharge at near-atmospheric pressure conditions (using 58·10 4 Pa of He). The particles exhibit a crystalline dense iron core with an average diameter 7.4 ± 2.0 nm surrounded by a sealed carbon shell, shown by transmission electron microscopy (TEM), selected-area diffrac- tion (SAED), energy-dispersive X-ray analysis (STEM-EDX) and electron energy loss spectroscopy (EELS). The SAED, EDX and EELS results indicate a lack of traces of core oxidized phases showing an efficient protection role of the carbon shell. The magnetic properties of the nanoparticles have been investigated in the 5300 K temperature range using a superconducting quantum interference device (SQUID). The results reveal a superparamagnetic behaviour with an average monodomain diameter of 7.6 nm of the nanoparticles. The zero field cooled and field cooled (ZFC-FC)magnetization curves show a blocking temperature (TB)at room temperature very suitable for biomedical applications (drug delivery, magnetic resonance imaging MRI, hyperthermia).
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The objective of this work was to characterize mandarin (Citrus spp.) germplasm from Southern Brazil by morphological and molecular analyses. Thirty seven cultivars from 34 distinct mandarin varieties were evaluated by morphological and agronomic traits of leaves, flowers and fruits, and by microsatellite markers. The morphological and agronomic characteristics suggested that almost all varieties can be produced for commercial use, and some, as the Satsuma variety, are recommended for breeding programs. Pooled DNA samples from 1-5 plants belonging to each cultivar were tested. Eight of the nine primers detected polymorphisms. Specific markers were found for some accessions. The dendrogram constructed with the morphological results divided the 37 cultivars into four groups, while that obtained with the microsatellites clustered 35 of the 37 cultivars into three groups only. Generally, intervarietal differences are not high, and this lack of agreement in the two multifactorial analyses indicates that diverse evolutionary factors are acting at these two levels of investigation.
Resumo:
Lorsque le cinéaste Julian Schnabel propose, dix ans après la sortie du livre "Le scaphandre et le papillon" de Jean-Dominique Bauby (1997), une "adaptation" de cette autobiographie, il prend pour sujet sa création même, en plaçant au premier plan les éléments qui, dans le péritexte, thématisaient les conditions de l'écriture. Bauby a en effet écrit cette autobiographie alors qu'il souffrait de locked-in syndrome, étant entièrement paralysé à l'exception de son oeil gauche. C'est avec l'oeil qu'il écrivait, dictant chaque lettre d'un battement de cils tandis qu'une assistante récitait à voix haute un code alphabétique. L'acte d'écriture devenait ainsi une performance audiovisuelle, saisissable cinématographiquement. Or, cet article montre comment Schnabel complexifie ce dispositif en faisant "plonger" le spectateur dans l'univers intérieur de Bauby à l'aide de procédés filmiques (caméra subjective, voix over à la première personne, flashbacks, visions) qui permettent de transposer toute la poésie et la force du texte. Narrant au "je" la vie, la pensée et les sens qui vibrent derrière les battements d'"aile" de cet oeil-papillon, cette autobiographie traduit de fait un univers visionnaire que Bauby lui-même appelle son "cinéma personnel". Schnabel actualise cette métaphore avec son film qui repousse les limites de la focalisation interne et met en abyme les pouvoirs du cinéma.