[Proceedings: Evolution of the rate of motor conduction and of distal latency of the internal popliteal sciatic nerve during exhausting muscular exercise].
Explore the source record for details and available documents.
Adolescent↗
SEARCH · Search PubMed
Results for “rate of evolution”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[Comparative evolution of heart rate and body temperature during muscular exercise at high temperature].
Explore the source record for details and available documents.
Adult↗
[Evolution of the rate of decrease in the indices of tuberculosis incidence and the affecting factors].
Explore the source record for details and available documents.
Adolescent↗
[The effect of coronary revascularization on the evolution of heart rate variability after a myocardial infarct. An evaluation in the time course and by spectral analysis].
Explore the source record for details and available documents.
Adult↗
Polarographic study of ammonia assimilation by isolated chloroplasts.
Illuminated pea (Pisum sativum) chloroplasts catalyze (ammonia plus alpha-ketoglutarate [alpha-KG])-dependent O(2) evolution at rates which are commensurate with other estimates of the flux of assimilated nitrogen (mean of eight determinations, 8.3 mumole per mg chlorophyll per hour, sd 2.4). The reaction was usually initiated with 1 mm ammonia after preincubating chloroplasts in the presence of alpha-KG, ADP, pyrophosphate, and MgCl(2).Progressive increases in ammonia concentration gave V(max)/2 at 0.2 mm (approximately) and V(max) at about 1 mm. Higher concentrations were inhibitory; at 7 mm the rate was again about V(max)/2. The highest ratio of O(2) evolved per mol of ammonia supplied was 0.36.The (ammonia plus alpha-KG)-dependent reaction was inhibited by methionine sulfoximine, azaserine, and aspartate in the presence of amino-oxyacetate but not by amino-oxyacetate alone and not by l-glutamate. The rate of O(2) evolution in the presence of 1 mm ammonia and 2.5 mm alpha-KG was increased only slightly by addition of 5 mm glutamine. Similarly, the rate of O(2) evolution in the presence of 5 mm glutamine and 2.5 mm alpha-KG was increased only slightly by addition of 1 mm ammonia.The results are attributed to the incorporation of ammonia via glutamine synthetase and reductive transamination of the glutamine formed by photosynthetically coupled glutamate synthase using alpha-KG as the amino acceptor. Several lines of evidence rule out the possibility that photosynthetically coupled glutamate dehydrogenase is involved.
Journal Article↗
Relative rates of nuclear DNA evolution in human and Old World monkey lineages.
Rates of substitution were compared between humans and Old World monkeys for sequences in or adjacent to 19 genes. The comparison of 21,299 sites in noncoding regions indicates that the substitution rate is approximately 43% greater in the Old World monkey lineage. However, 83% of the compared sites are in the region of the beta-globin gene family. Outside this region there is no consistent pattern of rate difference between the two lineages. Comparison of the coding regions of 16 genomically dispersed genes, involving 1,592 synonymous sites and 5,275 nonsynonymous sites, showed a faster rate of substitution in the human lineage at the nonsynonymous sites of the prion gene, but otherwise no evidence of rate difference between the two lineages. It is concluded that rate differences between these two lineages may be specific to certain regions of the genome rather than being a general phenomenon. This conclusion needs to be confirmed by comparison of a larger number of genomically dispersed sequences. It is, however, consistent with the results of DNA-DNA hybridization experiments, which show no difference in evolutionary rate between the two lineages.
Animals↗
Evolution of the maturation rate collapses competitive coexistence.
Most theoretical studies on character displacement and the coexistence of competing species have focused attention on the evolution of competitive traits driven by inter-specific competition. We investigated the evolution of the maturation rate which is not directly related to competition and trades off with the birth rate and how it influences competitive outcomes. Evolution may result in the superior competitor becoming extinct if, initially, the inferior competitor has a lower, and the superior one a higher, maturation rate at the coexistence equilibrium. This counterintuitive result is explained by an explosive increase in the adult population of the inferior competitor as a result of the more rapid evolution of its maturation rate, which is caused by differences in the intensity and direction of selection on the maturation rates of the two species and in their adult densities, which are related to differences in their life histories. Thus, a life history trait trade-off with a competitive trait may cause a competitive ecological coexistence to collapse.
Animals↗
Rates of DNA sequence evolution in experimental populations of Escherichia coli during 20,000 generations.
We examined rates of DNA sequence evolution in 12 populations of Escherichia coli propagated in a glucose minimal medium for 20,000 generations. Previous work saw mutations mediated by mobile elements in these populations, but the extent of other genomic changes was not investigated. Four of the populations evolved defects in DNA repair and became mutators. Some 500 bp was sequenced in each of 36 genes for 50 clones, including 2 ancestral variants, 2 clones from each population at generation 10,000, and 2 from each at generation 20,000. Ten mutations were found in total, all point mutations including mostly synonymous substitutions and nonsynonymous polymorphisms; all 10 were found in mutator populations. We compared the observed sequence evolution to predictions based on different scenarios. The number of synonymous substitutions is lower than predicted from measured mutation rates in E. coli, but the number is higher than rates based on comparing E. coli and Salmonella genomes. Extrapolating to the entire genome, these data predict about 250 synonymous substitutions on average per mutator population, but only about 3 synonymous substitutions per nonmutator population, during 20,000 generations. These data illustrate the challenge of finding sequence variation among bacterial isolates that share such a recent ancestor. However, this limited variation also provides a useful baseline for research aimed at finding the beneficial substitutions in these populations.
DNA, Bacterial↗
Contrasting rates of mitochondrial molecular evolution in parasitic Diptera and Hymenoptera.
We investigated the putative association between the parasitic lifestyle and an accelerated rate of mt genetic divergence, compositional bias, and gene rearrangement, employing a range of parasitic and nonparasitic Diptera and Hymenoptera. Sequences were obtained for the cox1, cox2, 16S, 28S genes, the regions between the cox2 and atp8 genes, and between the nad3 and nad5 genes. Relative rate tests indicated generally that the parasitic lifestyle was not associated with an increased rate of genetic divergence in the Diptera but reaffirmed that it was in the Hymenoptera. Similarly, a departure from compositional stationarity was not associated with parasitic Diptera but was in parasitic Hymenoptera. Finally, mitochondrial (mt) gene rearrangements were not observed in any of the dipteran species examined. The results indicate that these genetic phenomena are not accelerated in parasitic Diptera compared with nonparasitic Diptera. A possible explanation for the differences in the rate of mt molecular evolution in parasitic Diptera and Hymenoptera is the extraordinary level of radiation that has occurred within the parasitic Hymenoptera but not in any of the dipteran parasitic lineages. If speciation events in the parasitic Hymenoptera are associated with founder events, a faster rate of molecular evolution is expected. Alternatively, biological differences between endoparasitic Hymenoptera and endoparasitic Diptera may also account for the differences observed in molecular evolution.
Animals↗
Activating anions that replace Cl- in the O2-evolving complex of photosystem II slow the kinetics of the terminal step in water oxidation and destabilize the S2 and S3 states.
Photosystem II, the multisubunit protein complex that oxidizes water to O2, requires the inorganic cofactors Ca2+ and Cl- to exhibit optimal activity. Chloride can be replaced functionally by a small number of anionic cofactors (Br-, NO3-, NO2-, I-), but among these anions, only Br- is capable of restoring rates of oxygen evolution comparable to those observed with Cl-. UV absorption difference spectroscopy was utilized in the experiments described here as a probe to monitor donor side reactions in photosystem II in the presence of Cl- or surrogate anions. The rate of the final step of the water oxidation cycle was found to depend on the activating anion bound at the Cl- site, but the kinetics of this step did not limit the light-saturated rate of oxygen evolution. Instead, the lower oxygen evolution rates supported by surrogate anions appeared to be correlated with an instability of the higher oxidation states of the oxygen-evolving complex that was induced by addition of these anions. Reduction of these states takes place not only with I- but also with NO2- and to a lesser extent even with NO3- and Br- and is not related to the ability of these anions to bind at the Cl- binding site. Rather, it appears that these anions can attack higher oxidation states of the oxygen evolving complex from a second site that is not shielded by the extrinsic 17 and 23 kDa polypeptides and cause a one-electron reduction. The decrease of the oxygen evolution rate may result from accumulated damage to the reaction center protein by the one-electron oxidation product of the anion.
Anions↗
Rates of amino acid evolution in the 26- and 28-kDa glutathione S-transferases of Schistosoma.
Statistical analysis of glutathione S-transferase (GST) sequences of Schistosoma mansoni, Schistosoma japonicum, and other animals revealed that, in comparison both to the related mammalian alpha GSTs and to Schistosoma 26-kDa GSTs, the 28-kDa GSTs of Schistosoma have evolved unusually rapidly at the amino acid level in the ordinarily conserved N-terminal portion of the molecule. Because this rapid rate of evolution is reflected at the amino acid level and at nonsynonymous nucleotide sites but not at synonymous nucleotide sites, it must be due to a relaxation of functional constraint on the N-terminal region of the Schistosoma 28-kDa GSTs rather than to a high mutation rate. By contrast, the 26-kDa GSTs of Schistosoma not only show a slower rate of amino acid evolution in the N-terminal portion than the 28-kDa GSTs but also have evolved more slowly in the C-terminal portion than have the related mammalian mu GSTs. The two 26-kDa GSTs of S. mansoni show particularly strong amino acid conservation between one another in the N-terminal region and a predominance of conservative amino acid replacements.
Amino Acid Sequence↗
Determinants of rate variation in mammalian DNA sequence evolution.
Attempts to analyze variation in the rates of molecular evolution among mammalian lineages have been hampered by paucity of data and by nonindependent comparisons. Using phylogenetically independent comparisons, we test three explanations for rate variation which predict correlations between rate variation and generation time, metabolic rate, and body size. Mitochondrial and nuclear genes, protein coding, rRNA, and nontranslated sequences from 61 mammal species representing 14 orders are used to compare the relative rates of sequence evolution. Correlation analyses performed on differences in genetic distance since common origin of each pair against differences in body mass, generation time, and metabolic rate reveal that substitution rate at fourfold degenerate sites in two out of three protein sequences is negatively correlated with generation time. In addition, there is a relationship between the rate of molecular evolution and body size for two nuclear-encoded sequences. No evidence is found for an effect of metabolic rate on rate of sequence evolution. Possible causes of variation in substitution rate between species are discussed.
Age Factors↗
Mitochondrial DNA evolution in primates: transition rate has been extremely low in the lemur.
Based on mitochondrial DNA (mt-DNA) sequence data from a wide range of primate species, branching order in the evolution of primates was inferred by the maximum likelihood method of Felsenstein without assuming rate constancy among lineages. Bootstrap probabilities for the maximum likelihood tree topology among alternatives were estimated without performing a maximum likelihood estimation for each resampled data set. Variation in the evolutionary rate among lineages was examined for the maximum likelihood tree by a method developed by Kishino and Hasegawa. From these analyses it appears that the transition rate of mtDNA evolution in the lemur has been extremely low, only about 1/10 that in other primate lines, whereas the transversion rate does not differ significantly from that of other primates. Furthermore, the transition rate in catarrhines, except the gibbon, is higher than those in the tarsier and in platyrrhines, and the transition rate in the gibbon is lower than those in other catarrhines. Branching dates in primate evolution were estimated by a molecular clock analysis of mtDNA, taking into account the rate of variation among different lines, and the results were compared with those estimated from nuclear DNA. Under the most likely model, where the evolutionary rate of mtDNA has been uniform within a great apes/human clade, human/chimpanzee clustering is preferred to the alternative branching orders among human, chimpanzee, and gorilla.
Animals↗
Phenomenological theory of mortality evolution: its singularities, universality, and superuniversality.
The probability to survive to the age x universally increases with the mean lifespan x(bar). For species as remote as humans and flies, for a given x the rate of its evolution with x is constant, except for the narrow vicinity of a certain x(bar) = x* (which equals 75 years for humans and 32 days for flies and which is independent of age, population, and living conditions). At x(bar) approximately x* the evolution rate jumps to a different value. Its next jump is predicted at x(bar) approximately 87 years for humans and approximately 59 days for flies. Such singularities are well known in physics and mathematics as phase transitions. In the considered case different population "phases" have significantly different survival evolution rates. The evolution is rapid-life expectancy may double within a lifespan of a single generation. Survival probability depends on age x and mean longevity x(bar) only (for instance, survival curves of 1896 Swedes and 1947 Japanese with approximately equal x(bar) are very close, although they are related to different races in different countries at different periods in their different history.) With no adjustable parameters, its presented universal law quantitatively agrees with all lifetable data. According to this law, the impact of all factors but age reduces to the mean lifespan only. In advanced and old age, this law is superuniversal--it is approximately the same for species as remote as humans and flies. It yields survival probability that linearly depends on the mean lifespan x(bar). As a result, when human x(bar) almost doubles (from 35.5 to 69.3 years), life expectancy at 70 years increases from 8 to 9.5 years only. Other implications of the universal law are also considered.
Biological Evolution↗
[Evolution of cesarean section rates in Spain: 1984-1988].
The objective of this work is to describe the evolution of cesarean section rates in Spain from 1984 through 1988. National rates increased from 9.92% to 19.99%. Trend is significantly rising nationwide and in all Communities. Overall differences have decreased (CSV from 1.73 to 11.72) because there are two groups of regions: one with high rates, the other one with low rates. Rates are significantly higher in private hospitals (14.53%). These differences could show the controversy and uncertainty in the indications and the influence of organizational factors. Although new sources of information to obtain population rates and outcomes studies adjusted by women clinic and sociodemographic characteristics are due to be developed, these differences lead to suspect that there is a gap between the theoretic quality medical science could provide and the actual quality medical practice is providing, explained just by reasons out from clinical factors.
Adult↗
Premature cell ageing and evolution of diabetic nephropathy.
The rate of development and progression of renal disease varies greatly in insulin-dependent diabetic (IDDM) patients. The cellular and molecular reasons for this difference are largely unknown but could be related to early cell differentiation, a phenomenon recently reported in IDDM patients with nephropathy. In this study we compared cell differentiation and cell volume between IDDM patients with and without nephropathy and investigated the cell ageing characteristics in relation to the rate of evolution of renal disease in the IDDM patients with diabetic nephropathy. Cell volume was larger and the percentage of post-mitotic fibrocytes was higher in skin fibroblasts derived from IDDM patients with diabetic nephropathy compared to those from IDDM patients without kidney disease (mean +/- SD in arbitrary units 817.3 +/- 25.7 vs 760 +/- 32.8; p = 0.005; and mean +/- SD % 33.6 +/- 11.8 vs 20.8 +/- 10; p = 0.02 respectively). Analysis of the interaction of the time to proteinuria (TTP) and the rate of change of glomerular filtration rate (GFR) with glycaemic control, arterial blood pressure and cell volume and the state of cell differentiation showed that glycated haemoglobin and the percentage of post-mitotic fibrocytes were negatively correlated to TTP (r = -0.68; p = 0.008; r = 0.52; p = 0.05 respectively) and positively associated with the rate of change of GFR (r = 0.76; p = 0.03; r = 0.56; p = 0.037 respectively). Cell volume was negatively correlated to TTP (r = -0.53; p = 0.05). Diastolic blood pressure was also related to the rate of GFR change (r = 0.56; p = 0.039). In a multiple linear regression analysis glycated haemoglobin maintained its significance independent relationship with TTP at the 1% level, while the strength of the association between the percentage of post-mitotic cells and cell volume was reduced to the 11 and 9% level, respectively. Cultured skin fibroblasts from IDDM patients with nephropathy show signs of early differentiation. Glycaemic control is a key factor in the rate of onset of proteinuria and different rates of cell ageing appear to contribute to the rate of development and progression of diabetic nephropathy. Their interaction may be responsible for the severity of renal involvement in susceptible IDDM patients.
Adult↗
Body temperature, rate of biosynthesis, and evolution of genome size.
An optimality model relating the rate of biosynthesis to body temperature and gene duplication is presented to account for several observed patterns of genome size variation. The model predicts (1) that poikilotherms living in a warm climate should have a smaller genome than poikilotherms living in a cold climate, (2) that homeotherms should have a small genome as well as a small variation in genome size relative to their poikilothermic ancestors, (3) that cold geological periods should favor the evolution of poikilotherms with a large genome and that warm geological periods should do the opposite, and (4) that poikilotherms with a small genome should be more sensitive to changes in temperature than poikilotherms with a large genome. The model also offers two explanations for the empirically documented trend that organisms with a large cell volume have larger genomes than those with a small cell volume. Relevant empirical evidence is summarized to support these predictions.
Animals↗
Evolution of functionally conserved enhancers can be accelerated in large populations: a population-genetic model.
The evolution of cis-regulatory elements (or enhancers) appears to proceed at dramatically different rates in different taxa. Vertebrate enhancers are often very highly conserved in their sequences, and relative positions, across distantly related taxa. In contrast, functionally equivalent enhancers in closely related Drosophila species can differ greatly in their sequences and spatial organization. We present a population-genetic model to explain this difference. The model examines the dynamics of fixation of pairs of individually deleterious, but compensating, mutations. As expected, small populations are predicted to have a high rate of evolution, and the rate decreases with increasing population size. In contrast to previous models, however, this model predicts that the rate of evolution by pairs of compensatory mutations increases dramatically for population sizes above several thousand individuals, to the point of greatly exceeding the neutral rate. Application of this model predicts that species with moderate population sizes will have relatively conserved enhancers, whereas species with larger populations will be expected to evolve their enhancers at much higher rates. We propose that the different degree of conservation seen in vertebrate and Drosophila enhancers may be explained solely by differences in their population sizes and generation times.
Animals↗