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Genetic and physiological alterations occurring in a yeast population continuously propagated at increasing temperatures with cell recycling

Souza, Crisla S.; Thomaz, Daniel; Cides, Elaine R.; Oliveira, Karen F.; Tognolli, Joao O.; Laluce, Cecilia
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 1667-1677
ENG
Relevância na Pesquisa
45.88%
This work investigated the effects of increasing temperature from 30 degrees C to 47 degrees C on the physiological and genetic characteristics of Saccharomyces cerevisiae strain 63M after continuous fermentation with cell recycling in a system of five reactors in series. Steady state was attained at 30 degrees C, and then the temperature of the system was raised so it ranged from 35 degrees C in the last reactor to 43 degrees C in the first reactor or feeding reactor with a 2 degrees C difference between reactors. After 15 days at steady state, the temperature was raised from 37 degrees C to 45 degrees C for 25 days at steady state, then from 39 degrees C to 47 degrees C for 20 days at steady state. Starter strain 63M was a hybrid strain constructed to have a MAT a/alpha, LYS/lys, URA/ura genotype. This hybrid yeast showed vigorous growth on plates at 40 degrees C, weak growth at 41 degrees C, positive assimilation of melibiose, positive fermentation of galactose, raffinose and sucrose. of 156 isolates obtained from this system at the end of the fermentation process, only 17.3% showed the same characteristics as starter strain 63M. Alterations in mating type reaction and in utilization of raffinose, melibiose, and sucrose were identified. Only 1.9% of the isolates lost the ability to grow at 40 degrees C. Isolates showing requirements for lysine and uracil were also obtained. In addition...

Karyological, biochemical, and physiological aspects of Callophysus macropterus (Siluriformes, Pimelodidae) from the Solimões and Negro Rivers (Central Amazon)

Ramirez-Gil,H.; Feldberg,E.; Almeida-Val,V.M.F.; Val,A.L.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/1998 EN
Relevância na Pesquisa
46.06%
Karyological characteristics, i.e., diploid number, chromosome morphology and nucleolus organizer regions (NORs), biochemical characteristics, i.e., electrophoretic analysis of blood hemoglobin and the tissue enzymes lactate dehydrogenase (LDH), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), and phosphoglucose isomerase (PGI), and physiological characteristics, i.e., relative concentration of hemoglobin and intraerythrocytic concentrations of organic phosphates were analyzed for the species Callophysus macropterus collected from Marchantaria Island (white water system - Solimões River) and Anavilhanas Archipelago (black water system - Negro River). Karyological and biochemical data did not reveal significant differences between specimens collected at the two sites. However, the relative distribution of hemoglobin bands I and III (I = 16.33 ± 1.05 and III = 37.20 ± 1.32 for Marchantaria specimens and I = 6.33 ± 1.32 and III = 48.05 ± 1.55 for Anavilhanas specimens) and levels of intraerythrocytic GTP (1.32 ± 0.16 and 2.76 ± 0.18 for Marchantaria and Anavilhanas specimens, respectively), but not ATP or total phosphate, were significantly different, indicating a physiological adaptation to the environmental conditions of these habitats. It is suggested that C. macropterus specimens from the two collecting sites belong to a single population...

Genetic and Physiological Adaptation of the Copepod EURYTEMORA AFFINIS to Seasonal Temperatures

Bradley, Brian P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1978 EN
Relevância na Pesquisa
45.96%
Evidence of significant additive genetic (genic) variance in temperature tolerance of the copepod Eurytemora affinis was derived from several sources. Differences were observed between average tolerances of progeny of animals exposed and not exposed to heat shock in a power plant. Genic variance was estimated using offspring-parent regressions, full-sib, and half-sib covariances, with quite consistent results. Expressed genic variance between male progeny was always higher than that among female progeny.—The pairs of estimates obtained were as follows: female heritabilities first, 0.40 ± 0.09 and 0.84 ± 0.35 (half-sibs); 0.20 ± 0.09 and 0.79 ± 0.24 (full-sibs); 0.11 ± 0.10 and 0.89 ± 0.45 (full-sibs); 0.28 ± 0.18 and 0.78 ± 0.29 (full-sibs); 0.11 ± 0.44 and 0.72 ± 0.26 (offspring-parent regression). There was no evidence of either nonadditive genetic variance or common environmental (maternal and brood) effects, implying that the genetic variance was mostly additive and was not maintained because of heterozygous advantage.—The presence of so much genetic variance is surprising in view of the high physiological adaptation found earlier, especially in females.

Interstrain variation in cardiac and respiratory adaptation to repeated ozone and particulate matter exposures

Hamade, Ali K.; Tankersley, Clarke G.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.26%
Increased ambient particulate matter (PM) is associated with adverse cardiovascular and respiratory outcomes, as demonstrated by epidemiology studies. Several studies have investigated the role of copollutants, such as ozone (O3), in this association. It is accepted that physiological adaptation involving the respiratory system occurs with repeated exposures to O3. We hypothesize that adaptation to PM and O3 varies among different inbred mouse strains, and cardiopulmonary adaptation to O3 is a synchronized response between the cardiac and respiratory systems. Heart rate (HR), HR variability (HRV), and the magnitude and pattern of breathing were simultaneously measured by implanted telemeters and by plethysmography in three inbred mouse strains: C57Bl/6J (B6), C3H/HeJ (HeJ), and C3H/HeOuJ (OuJ). Physiological responses were assessed during dual exposures to filtered air (FA), O3 (576 ± 32 parts/billion), and/or carbon black (CB; 556 ± 34 μg/m3). Exposures were repeated for 3 consecutive days. While each strain showed significant reductions in HR during CB with O3 preexposure (O3CB) on day 1, prominent HRV responses were observed in only HeJ and OuJ mice. Each strain also differed in their adaptation profile in response to repeated O3CB exposures. Whereas B6 mice showed rapid adaptation in HR after day 1...

Whole transcriptome analysis of the fasting and fed Burmese python heart: insights into extreme physiological cardiac adaptation

Wall, Christopher E.; Cozza, Steven; Riquelme, Cecilia A.; McCombie, W. Richard; Heimiller, Joseph K.; Marr, Thomas G.; Leinwand, Leslie A.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.92%
The infrequently feeding Burmese python (Python molurus) experiences significant and rapid postprandial cardiac hypertrophy followed by regression as digestion is completed. To begin to explore the molecular mechanisms of this response, we have sequenced and assembled the fasted and postfed Burmese python heart transcriptomes with Illumina technology using the chicken (Gallus gallus) genome as a reference. In addition, we have used RNA-seq analysis to identify differences in the expression of biological processes and signaling pathways between fasted, 1 day postfed (DPF), and 3 DPF hearts. Out of a combined transcriptome of ∼2,800 mRNAs, 464 genes were differentially expressed. Genes showing differential expression at 1 DPF compared with fasted were enriched for biological processes involved in metabolism and energetics, while genes showing differential expression at 3 DPF compared with fasted were enriched for processes involved in biogenesis, structural remodeling, and organization. Moreover, we present evidence for the activation of physiological and not pathological signaling pathways in this rapid, novel model of cardiac growth in pythons. Together, our data provide the first comprehensive gene expression profile for a reptile heart.

The Matricellular Protein Cysteine-rich Protein 61 (CCN1/Cyr61) Enhances Physiological Adaptation of Retinal Vessels and Reduces Pathological Neovascularization Associated with Ischemic Retinopathy*

Hasan, Adeel; Pokeza, Nataliya; Shaw, Lynn; Lee, Hyun-Seung; Lazzaro, Douglas; Chintala, Hemabindu; Rosenbaum, Daniel; Grant, Maria B.; Chaqour, Brahim
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.1%
Retinal vascular damages are the cardinal hallmarks of retinopathy of prematurity (ROP), a leading cause of vision impairment and blindness in childhood. Both angiogenesis and vasculogenesis are disrupted in the hyperoxia-induced vaso-obliteration phase, and recapitulated, although aberrantly, in the subsequent ischemia-induced neovessel formation phase of ROP. Yet, whereas the histopathological features of ROP are well characterized, many key modulators with a therapeutic potential remain unknown. The CCN1 protein also known as cysteine-rich protein 61 (Cyr61) is a dynamically expressed, matricellular protein required for proper angiogenesis and vasculogenesis during development. The expression of CCN1 becomes abnormally reduced during the hyperoxic and ischemic phases of ROP modeled in the mouse eye with oxygen-induced retinopathy (OIR). Lentivirus-mediated re-expression of CCN1 enhanced physiological adaptation of the retinal vasculature to hyperoxia and reduced pathological angiogenesis following ischemia. Remarkably, injection into the vitreous of OIR mice of hematopoietic stem cells (HSCs) engineered to express CCN1 harnessed ischemia-induced neovessel outgrowth without adversely affecting the physiological adaptation of retinal vessels to hyperoxia. In vitro exposure of HSCs to recombinant CCN1 induced integrin-dependent cell adhesion...

PSYCHOSOCIAL INTERVENTION EFFECTS ON ADAPTATION, DISEASE COURSE AND BIOBEHAVIORAL PROCESSES IN CANCER

Antoni, Michael H.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.24%
A diagnosis of cancer and subsequent treatments place demands on psychological adaptation. Behavioral research suggests the importance of cognitive, behavioral, and social factors in facilitating adaptation during active treatment and throughout cancer survivorship, which forms the rationale for the use of many psychosocial interventions in cancer patients. This cancer experience may also affect physiological adaptation systems (e.g., neuroendocrine) in parallel with psychological adaptation changes (negative affect). Changes in adaptation may alter tumor growth-promoting processes (increased angiogenesis, migration and invasion, and inflammation) and tumor defense processes (decreased cellular immunity) relevant for cancer progression and the quality of life of cancer patients. Some evidence suggests that psychosocial intervention can improve psychological and physiological adaptation indicators in cancer patients. However, less is known about whether these interventions can influence tumor activity and tumor growth-promoting processes and whether changes in these processes could explain the psychosocial intervention effects on recurrence and survival documented to date. Documenting that psychosocial interventions can modulate molecular activities (e.g....

Compensation of the Metabolic Costs of Antibiotic Resistance by Physiological Adaptation in Escherichia coli

Händel, Nadine; Schuurmans, J. Merijn; Brul, Stanley; ter Kuile, Benno H.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2013 EN
Relevância na Pesquisa
46.02%
Antibiotic resistance is often associated with metabolic costs. To investigate the metabolic consequences of antibiotic resistance, the genomic and transcriptomic profiles of an amoxicillin-resistant Escherichia coli strain and the wild type it was derived from were compared. A total of 125 amino acid substitutions and 7 mutations that were located <1,000 bp upstream of differentially expressed genes were found in resistant cells. However, broad induction and suppression of genes were observed when comparing the expression profiles of resistant and wild-type cells. Expression of genes involved in cell wall maintenance, DNA metabolic processes, cellular stress response, and respiration was most affected in resistant cells regardless of the absence or presence of amoxicillin. The SOS response was downregulated in resistant cells. The physiological effect of the acquisition of amoxicillin resistance in cells grown in chemostat cultures consisted of an initial increase in glucose consumption that was followed by an adaptation process. Furthermore, no difference in maintenance energy was observed between resistant and sensitive cells. In accordance with the transcriptomic profile, exposure of resistant cells to amoxicillin resulted in reduced salt and pH tolerance. Taken together...

Eco-physiological adaptation of dominant tree species at two contrasting karst habitats in southwestern China

Zhang, Shouren; Fan, Dayong; Wu, Qian; Yan, Hui; Xu, Xinwu
Fonte: F1000Research Publicador: F1000Research
Tipo: Artigo de Revista Científica
Publicado em 25/11/2013 EN
Relevância na Pesquisa
46.02%
The purpose of this study was to investigate the eco-physiological adaptation of indigenous woody species to their habitats in karst areas of southwestern China. Two contrasting forest habitats were studied: a degraded habitat in Daxiagu and a well-developed habitat in Tianlongshan, and the eco-physiological characteristics of the trees were measured for three growth seasons. Photosynthetic rate (Pn), stomatal conductance (gs), and transpiration rate (Tr) of the tree species in Daxiagu were 2-3 times higher than those in Tianlongshan under ambient conditions. However, this habitat effect was not significant when measurements were taken under controlled conditions. Under controlled conditions, Pn, gs, and Tr of the deciduous species were markedly higher than those for the evergreen species. Habitat had no significant effect on water use efficiency (WUE) or photochemical characteristics of PSII. The stomatal sensitivity of woody species in the degraded habitat was much higher than that in the well-developed habitat. Similarly, the leaf total nitrogen (N) and phosphorus (P) contents expressed on the basis of either dry mass or leaf area were also much higher in Daxiagu than they were in Tianlongshan. The mass-based leaf total N content of deciduous species was much higher than that of evergreen species...

Evolution after Introduction of a Novel Metabolic Pathway Consistently Leads to Restoration of Wild-Type Physiology

Carroll, Sean; Marx, Christopher J
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.22%
Organisms cope with physiological stressors through acclimatizing mechanisms in the short-term and adaptive mechanisms over evolutionary timescales. During adaptation to an environmental or genetic perturbation, beneficial mutations can generate numerous physiological changes: some will be novel with respect to prior physiological states, while others might either restore acclimatizing responses to a wild-type state, reinforce them further, or leave them unchanged. We examined the interplay of acclimatizing and adaptive responses at the level of global gene expression in Methylobacterium extorquens AM1 engineered with a novel central metabolism. Replacing central metabolism with a distinct, foreign pathway resulted in much slower growth than wild-type. After 600 generations of adaptation, however, eight replicate populations founded from this engineered ancestor had improved up to 2.5-fold. A comparison of global gene expression in wild-type, engineered, and all eight evolved strains revealed that the vast majority of changes during physiological adaptation effectively restored acclimatizing processes to wild-type expression states. On average, 93% of expression perturbations from the engineered strain were restored, with 70% of these occurring in perfect parallel across all eight replicate populations. Novel changes were common but typically restricted to one or a few lineages...

Physiological attributes of drought-adaptation and associated molecular markers in the seri/babax hexaploid wheat (Triticum aestivum, L.) population.

Olivares-Villegas, Juan Jose
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2007
Relevância na Pesquisa
36.26%
Agronomic and physiological traits associated with drought adaptation were assessed within the Seri/Babax recombinant inbred line population, derived from parents similar in height and maturity but divergent in their sensitivity to drought. Field trials under different water regimes were conducted over three years in Mexico and under rainfed conditions in Australia. Under drought, canopy temperature (CT) was the single-most drought-adaptive trait contributing to a higher performance (R2= 0.71, p<0.0001), highly heritable (h2= 0.65, p<0.0001) and consistently associated with yield phenotypically (r= -0.75, p<0.0001) and genetically [R(g)= -0.95, p<0.0001]. CT epitomises a mechanism of dehydration avoidance expressed throughout the growing season and across latitudes, which can be utilised as a selection criteria to identify high-yielding wheat genotypes or as an important predictor of yield performance under drought. Early response under drought, suggested by a high association of CT with estimates of biomass at booting (r= -0.44, p<0.0001), leaf chlorophyll (r= -0.22,p<0.0001) and plant height (r= -0.64, p<0.0001), contrast with the small relationships with anthesis and maturity (averaged, r= -0.10, p<0.0001), and with osmotic potential (r= -0.20...

The role of oxidative, inflammatory and neuroendocrinological systems during exercise stress in athletes: implications of antioxidant supplementation on physiological adaptation during intensified physical training

Slattery, K.; Bentley, D.; Coutts, A.J.
Fonte: Springer International Publishing Publicador: Springer International Publishing
Tipo: Artigo de Revista Científica
Publicado em //2015 EN
Relevância na Pesquisa
46.14%
During periods of intensified physical training, reactive oxygen species (ROS) release may exceed the protective capacity of the antioxidant system and lead to dysregulation within the inflammatory and neuroendocrinological systems. Consequently, the efficacy of exogenous antioxidant supplementation to maintain the oxidative balance in states of exercise stress has been widely investigated. The aim of this review was to (1) collate the findings of prior research on the effect of intensive physical training on oxidant–antioxidant balance; (2) summarise the influence of antioxidant supplementation on the reduction-oxidation signalling pathways involved in physiological adaptation; and (3) provide a synopsis on the interactions between the oxidative, inflammatory and neuroendocrinological response to exercise stimuli. Based on prior research, it is evident that ROS are an underlying aetiology in the adaptive process; however, the impact of antioxidant supplementation on physiological adaptation remains unclear. Equivocal results have been reported on the impact of antioxidant supplementation on exercise-induced gene expression. Further research is required to establish whether the interference of antioxidant supplementation consistently observed in animal-based and in vivo research extends to a practical sports setting. Moreover...

Efeitos de dois protocolos de adaptação ao meio líquido com intensidades diferentes sobre os parâmetros fisiológicos, de desempenho e padrão de nado de ratos Wistar; Effects of two protocols adaptation of water with different intensities on the physiological parameters, performance and Wistar rat swimming standard

Adriano Alves de Lima
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/07/2015 PT
Relevância na Pesquisa
36.18%
Esse estudo tem como objetivo analisar os efeitos de dois protocolos de adaptação ao meio líquido com intensidades sub e supra limiar anaeróbio sobre parâmetros fisiológicos, de desempenho e padrão de nado de ratos Wistar. Foram utilizados 108 ratos Wistar, sendo 12 animais compondo o grupo de base e 96 animais divididos em 6 grupos (dois controle e quatro experimentais). Os grupos controle 1 e 2 (GC1 e GC2, respectivamente), não foram adaptados ao meio líquido e foram submetidos a uma avaliação aeróbia/anaeróbia (teste de lactato mínimo - TLM) em momentos distintos, sendo o GC1 realizado o TLM apenas a0s 90 dias, enquanto o GC2 aos 77 e 90 dias. Nos grupos experimentais (n=16 por grupo), foram aplicadas intensidades abaixo e acima do limiar anaeróbio (Sub-Lan e Supra-Lan, respectivamente) no período de adaptação ao meio líquido, sendo que os grupos Supra-Lan2 e Sub-Lan2 realizaram o TLM no momento pré e pós adaptação, enquanto os grupos Supra-Lan1 e Sub-Lan1 apenas no momento pós adaptação (90 dias). A adaptação ao meio líquido foi composta de 14 dias ininterruptos, tendo início com água rasas e posteriormente no quarto dia em água profunda. Os protocolos se diferenciaram a partir do 10o dia, onde o grupo Sub-Lan se caracteriza pelo aumento do volume da sessão e manutenção da intensidade...

Exercise and Training at Altitudes: Physiological Effects and Protocols

Olga Cecilia Vargas Pinilla
Fonte: Universidade do Rosário Publicador: Universidade do Rosário
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em 15/01/2014 SPA
Relevância na Pesquisa
45.95%
An increase in altitude leads to a proportional fall in the barometric pressure, and a decrease in atmospheric oxygen pressure, producing hypobaric hypoxia that affects, in different degrees, all body organs, systems and functions. The chronically reduced partial pressure of oxygen causes that individuals adapt and adjust to physiological stress. These adaptations are modulated by many factors, including the degree of hypoxia related to altitude, time of exposure, exercise intensity and individual conditions. It has been established that exposure to high altitude is an environmental stressor that elicits a response that contributes to many adjustments and adaptations that influence exercise capacity and endurance performance. These adaptations include in crease in hemoglobin concentration, ventilation, capillary density and tissue myoglobin concentration. However, a negative effect in strength and power is related to a decrease in muscle fiber size and body mass due to the decrease in the training intensity. Many researches aim at establishing how training or living at high altitudes affects performance in athletes. Training methods, such as living in high altitudes training low, and training high-living in low altitudes have been used to research the changes in the physical condition in athletes and how the physiological adaptations to hypoxia can enhanceperformance at sea level. This review analyzes the literature related to altitude training focused on how physiological adaptations to hypoxic environments influence performance...

Hypoxia Inducible Factor Pathway and Physiological Adaptation: A Cell Survival Pathway?

Kumar, Hemant; Choi, Dong-Kug
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.2%
Oxygen homeostasis reflects the constant body requirement to generate energy. Hypoxia (0.1–1% O2), physioxia or physoxia (∼1–13%), and normoxia (∼20%) are terms used to define oxygen concentration in the cellular environment. A decrease in oxygen (hypoxia) or excess oxygen (hyperoxia) could be deleterious for cellular adaptation and survival. Hypoxia can occur under both physiological (e.g., exercise, embryonic development, underwater diving, or high altitude) and pathological conditions (e.g., inflammation, solid tumor formation, lung disease, or myocardial infarction). Hypoxia plays a key role in the pathophysiology of heart disease, cancers, stroke, and other causes of mortality. Hypoxia inducible factor(s) (HIFs) are key oxygen sensors that mediate the ability of the cell to cope with decreased oxygen tension. These transcription factors regulate cellular adaptation to hypoxia and protect cells by responding acutely and inducing production of endogenous metabolites and proteins to promptly regulate metabolic pathways. Here, we review the role of the HIF pathway as a metabolic adaptation pathway and how this pathway plays a role in cell survival. We emphasize the roles of the HIF pathway in physiological adaptation, cell death...

Variability in training-induced skeletal muscle adaptation

Timmons, James A.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.04%
When human skeletal muscle is exposed to exercise training, the outcomes, in terms of physiological adaptation, are unpredictable. The significance of this fact has long been underappreciated, and only recently has progress been made in identifying some of the molecular bases for the heterogeneous response to exercise training. It is not only of great medical importance that some individuals do not substantially physiologically adapt to exercise training, but the study of the heterogeneity itself provides a powerful opportunity to dissect out the genetic and environmental factors that limit adaptation, directly in humans. In the following review I will discuss new developments linking genetic and transcript abundance variability to an individual's potential to improve their aerobic capacity or endurance performance or induce muscle hypertrophy. I will also comment on the idea that certain gene networks may be associated with muscle “adaptability” regardless the stimulus provided.

Evolution of adaptation mechanisms: adaptation energy, stress, and oscillating death

Gorban, A. N.; Tyukina, T. A.; Smirnova, E. V.; Pokidysheva, L. I.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/12/2015
Relevância na Pesquisa
36.22%
In 1938, H. Selye proposed the notion of adaptation energy and published "Experimental evidence supporting the conception of adaptation energy". Adaptation of an animal to different factors appears as the spending of one resource. Adaptation energy is a hypothetical extensive quantity spent for adaptation. This term causes much debate when one takes it literally, as a physical quantity, i.e. a sort of energy. The controversial points of view impede the systematic use of the notion of adaptation energy despite experimental evidence. Nevertheless, the response to many harmful factors often has general non-specific form and we suggest that the mechanisms of physiological adaptation admit a very general and nonspecific description. We aim to demonstrate that Selye's adaptation energy is the cornerstone of the top-down approach to modelling of non-specific adaptation processes. We analyse Selye's axioms of adaptation energy together with Goldstone's modifications and propose a series of models for interpretation of these axioms. {\em Adaptation energy is considered as an internal coordinate on the `dominant path' in the model of adaptation}. The phenomena of `oscillating death' and `oscillating remission' are predicted on the base of the dynamical models of adaptation. Natural selection plays a key role in the evolution of mechanisms of physiological adaptation. We use the fitness optimization approach to study of the distribution of resources for neutralization of harmful factors...

Relationship Between Contrast Adaptation and Orientation Tuning in V1 and V2 of Cat Visual Cortex

Crowder, Nathan; Price, N; Hietanen, Markus; Dreher, B; Clifford, Colin W.G.; Ibbotson, Michael
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.08%
Previous studies investigating the response properties of neurons in the primary visual cortex of cats and primates have shown that prolonged exposure to optimally oriented, high-contrast gratings leads to a reduction in responsiveness to subsequently presented test stimuli. We recorded from 119 neurons in cat V1 and V2 and found that in a high proportion of cells contrast adaptation also occurs for gratings oriented orthogonal to a neuron's preferred orientation, even though this stimulus did not elicit significant increases in spiking activity. Approximately 20% of neurons adapted equally to all orientations tested and a further 46% showed at least some adaptation to orthogonally oriented gratings, whereas 20% of neurons did not adapt to orthogonal gratings. The magnitude of contrast adaptation was positively correlated with adapting contrast, but was not related to the spiking activity of the cells. Highly direction selective neurons produced stronger adaptation to orthogonally oriented gratings than other neurons. Orientation-related adaptation was correlated with the rate of change of orientation tuning in consecutive cells along electrode penetrations that traveled parallel to the cortical layers. Nonoriented adaptation was most common in areas where orientation preference changed rapidly...

Contrast and Temporal Frequency-Related Adaptation in the Prectal Nucleus of the Optic Tract

Ibbotson, Michael
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.07%
In mammals, many cells in the retino-geniculate-cortical pathway adapt during stimulation with high contrast gratings. In the visual cortex, adaptation to high contrast images reduces sensitivity at low contrasts while only moderately affecting sensitivity at high contrasts, thus generating rightward shifts in the contrast response functions (contrast gain control). Similarly, motion adaptation at particular temporal frequencies (TFs) alters the temporal tuning properties of cortical cells. For the first time in any species, this paper investigates the influence of motion adaptation on both the contrast and TF responses of neurons in the retino-pretectal pathway by recording from direction-selective neurons in the nucleus of the optic tract (NOT) of the marsupial wallaby, Macropus eugenii. This species is of interest because its NOT receives almost all input directly from the retina, with virtually none from the visual cortex (unlike cats and primates). All NOT cells show changes in their contrast response functions after adaptation, many revealing contrast gain control. Contrast adaptation is direction-dependent, preferred directions producing the largest changes. The lack of cortical input suggests that contrast adaptation is generated independently from the cortex in the NOT or retina. Motion adaptation also produces direction-selective effects on the TF tuning of NOT neurons by shifting the location of the optimum TF. Cells that show strong adaptation to contrast also tend to show large changes in TF tuning...

COMMON PROBLEMS OF PHYSIOLOGICAL ADAPTATION IN WOMEN WITH ANGINA PECTORIS; PROBLEMAS COMUNS DE ADAPTAÇÃO FISIOLÓGICA EM MULHERES COM ANGINA PECTORIS

Lopes, Marcos Venícios de Oliveira; Araujo, Thelma Leite de
Fonte: Universidade Federal do Paraná Publicador: Universidade Federal do Paraná
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; Formato: application/pdf
Publicado em // POR
Relevância na Pesquisa
46.11%
Descriptive and exploratory study in order to settle the main and most common physical adaptation problems with women with angina, with basis in Roy’s Adaptation Model (1991). The study was developed with 24 women who were interned in a private hospital at Fortaleza – CE, from March to May, 1998. The instrument used for data collection was an evaluation of incentives and behaviors which included the components of the physiologic mode proposed by the theoretic model adopted. The reached results allowed to identify several adaptation problems and their respective focal, contextual and residual incentives. The application of the theoretical model was considered important and suitable to the work close to women with angina pectoris.; Estudo descritivo e exploratório objetivando determinar os principais problemas comuns de adaptação fisiológica presentes em mulheres com angina, tendo como base o Modelo da adaptação de Roy & Andrews (1991). O estudo foi desenvolvido junto a 24 mulheres internadas num hospital da rede privada da cidade de Fortaleza – CE no período de março a maio de 1998. O instrumento para coleta de dados utilizado foi uma avaliação de estímulos e comportamentos que incluía os componentes do modo fisiológico proposto pelo modelo teórico adotado. Os resultados alcançados permitiram-nos identificar diversos problemas de adaptação e seus respectivos estímulos focais...