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At least 451 records · Page 25Linked to original sources
PubMed2025

Reproductive Isolation due to Divergent Ecological Selection Is Accompanied by Vast Genomic Instability in Experimentally Evolved Yeast Populations.

Populations evolving independently in divergent environments accumulate genetic differences and potentially evolve reproductive isolation as a by-product of divergence. The speed and mechanisms underlying this process are difficult to investigate because we rarely get the opportunity to witness them in natural settings, and histories of selection and gene flow between populations are often unknown. Here, we experimentally evolved yeast for 1000 generations of evolution in both divergent and parallel environments. At regular time points during experimental evolution, we made crosses between parallel- and divergent-evolving populations to measure postzygotic reproductive isolation (gamete viability). We used whole genome population sequencing to determine the mutational load, the number and types of structural variation, and other genomic features of the parent, F1 and F2 intraspecific hybrids. We found evidence for large-scale phenotypic and genome-wide differentiation in response to divergent laboratory selection. Divergent-selected populations produced hybrids with reduced gamete viability-a classic signature of postzygotic reproductive isolation in the form of hybrid breakdown. Parallel-selected populations, on the other hand, remained more reproductively compatible (with exceptions). We found that F2 hybrid genomes contained vast genomic instability, that is, new structural variants (especially insertions, deletions and interchromosomal translocations) that were not observed in parent and F1 genomes, which is likely a result of chromosome missegregation and recombination errors in hybrid meiosis. Our results provide phenotypic and genomic evidence that partial reproductive isolation evolved due to adaptation to divergent environments, consistent with predictions of ecological speciation theory.

Reproductive Isolation↗
PubMed1984

Meal to meal energy balance in rats.

Meal to meal energy balance was examined in thirty-eight simultaneous recordings of feeding pattern and O2 consumption in six rats. The mean difference between energy intake in a meal and energy expenditure until the onset of the next meal was found positive at night and negative during day time. At night the excess of meal intake over meal to meal expenditures was decreasing from the beginning to the end of the night and was strongly correlated to meal sizes. During day time meal to meal deficit was decreasing from the beginning to the end of the period but was not correlated to meal sizes. These meal location and size effects on the meal to meal energy balance were not determined by an effect of these factors on metabolic rate. No indication was provided that meal to meal energy balance was influenced by a "meal induced thermogenesis." Rather an evolution from the beginning to the end of the night of the correlation between meal size and durations of meal to meal intervals was found to be parallel to the evolution of positive meal to meal energy balance throughout the night. From these data it is concluded that at night a dual utilization of meal caloric intake (current energy metabolism plus fat storage) and a dual source of fuel during the day (food plus mobilized fats) determine time and mechanism of meal onset.

Animals↗
PubMedDate not supplied

[Aging and atherosclerosis of human aorta. Comparative evolution of seven glycosyl-transferases and of lactate-dehydrogenase (author's transl)].

Seven glycosyl-transferases and the lactico-dehydrogenase from human aortas were assayed. These aortas were divided in five classes according to the age and in five steps according to the atherogenesis. These enzymic activities do not show any parallelism in their evolution; their variation with age and with atherogenesis is quite different. For example, the N-acetylgalactosaminyl-transferase activity increases with atherogenesis whereas it diminishes with age; on the other hand the lactate-dehydrogenase activity increases with age and decreases with atherogenesis; the sialyl-transferase activity is nearly constant during adulthood while it hardly declines with atherogenesis. These assays suggest: 1) an effect of energy metabolism on the glycosyl-transferase activities; 2) a qualitative and quantitative variation of the glycosaminoglycans biosynthesis; 3) a structural modification of the glucidic part of the glycoproteins which can induce the formation of antigenic sites.

Adolescent↗
PubMed1998

Evolution of the cytochrome P450 superfamily: sequence alignments and pharmacogenetics.

The evolution of the cytochrome P450 (CYP) superfamily is described, with particular reference to major events in the development of biological forms during geological time. It is noted that the currently accepted timescale for the elaboration of the P450 phylogenetic tree exhibits close parallels with the evolution of terrestrial biota. Indeed, the present human P450 complement of xenobiotic-metabolizing enzymes may have originated from coevolutionary 'warfare' between plants and animals during the Devonian period about 400 million years ago. A number of key correspondences between the evolution of P450 system and the course of biological development over time, point to a mechanistic molecular biology of evolution which is consistent with a steady increase in atmospheric oxygenation beginning over 2000 million years ago, whereas dietary changes during more recent geological time may provide one possible explanation for certain species differences in metabolism. Alignment between P450 protein sequences within the same family or subfamily, together with across-family comparisons, aid the rationalization of drug metabolism specificities for different P450 isoforms, and can assist in an understanding of genetic polymorphisms in P450-mediated oxidations at the molecular level. Moreover, the variation in P450 regulatory mechanisms and inducibilities between different mammalian species are likely to have important implications for current procedures of chemical safety evaluation, which rely on pure genetic strains of laboratory bred rodents for the testing of compounds destined for human exposure.

Amino Acid Sequence↗
PubMedDate not supplied

[Sacrococcygeal teratoma in the adult].

Problems of diagnosis, classification, and histologic definition, as well as possibilities of evolution are discussed, of teratomas or of tumours resulting from the disturbed development of the sacro-coccygeal area, in connection with a case of recidivating sacro-coccygeal teratoma in a woman aged 40 years. The therapeutic principles are also discussed The risk of malignant degeneration of these lesions, in parallel with their evolution in time, make necessary surgical exeresis immediately after making the diagnosis. Surgery should be performed with a maximum amount of comfort, under general anesthesia, preferably in the Kraske position, in view of the complete extirpation of pathological tissues. Resection of the coccyx and of the last sacral vertebrae allows to widen the approach, facilitating the complete exeresis, and avoiding the two risks which are characteristic for this intervention: lesion of the rectum, and haemorrhage which is difficult to control. The postoperative aspiratory draining is useful for the favourable evolution of the wound.

Adult↗
PubMed2006

Genetics, development and evolution of adaptive pigmentation in vertebrates.

The study of pigmentation has played an important role in the intersection of evolution, genetics, and developmental biology. Pigmentation's utility as a visible phenotypic marker has resulted in over 100 years of intense study of coat color mutations in laboratory mice, thereby creating an impressive list of candidate genes and an understanding of the developmental mechanisms responsible for the phenotypic effects. Variation in color and pigment patterning has also served as the focus of many classic studies of naturally occurring phenotypic variation in a wide variety of vertebrates, providing some of the most compelling cases for parallel and convergent evolution. Thus, the pigmentation model system holds much promise for understanding the nature of adaptation by linking genetic changes to variation in fitness-related traits. Here, I first discuss the historical role of pigmentation in genetics, development and evolutionary biology. I then discuss recent empirically based studies in vertebrates, which rely on these historical foundations to make connections between genotype and phenotype for ecologically important pigmentation traits. These studies provide insight into the evolutionary process by uncovering the genetic basis of adaptive traits and addressing such long-standing questions in evolutionary biology as (1) are adaptive changes predominantly caused by mutations in regulatory regions or coding regions? (2) is adaptation driven by the fixation of dominant mutations? and (3) to what extent are parallel phenotypic changes caused by similar genetic changes? It is clear that coloration has much to teach us about the molecular basis of organismal diversity, adaptation and the evolutionary process.

Adaptation, Biological↗
PubMed2000

An ancestral MADS-box gene duplication occurred before the divergence of plants and animals.

Changes in genes encoding transcriptional regulators can alter development and are important components of the molecular mechanisms of morphological evolution. MADS-box genes encode transcriptional regulators of diverse and important biological functions. In plants, MADS-box genes regulate flower, fruit, leaf, and root development. Recent sequencing efforts in Arabidopsis have allowed a nearly complete sampling of the MADS-box gene family from a single plant, something that was lacking in previous phylogenetic studies. To test the long-suspected parallel between the evolution of the MADS-box gene family and the evolution of plant form, a polarized gene phylogeny is necessary. Here we suggest that a gene duplication ancestral to the divergence of plants and animals gave rise to two main lineages of MADS-box genes: TypeI and TypeII. We locate the root of the eukaryotic MADS-box gene family between these two lineages. A novel monophyletic group of plant MADS domains (AGL34 like) seems to be more closely related to previously identified animal SRF-like MADS domains to form TypeI lineage. Most other plant sequences form a clear monophyletic group with animal MEF2-like domains to form TypeII lineage. Only plant TypeII members have a K domain that is downstream of the MADS domain in most plant members previously identified. This suggests that the K domain evolved after the duplication that gave rise to the two lineages. Finally, a group of intermediate plant sequences could be the result of recombination events. These analyses may guide the search for MADS-box sequences in basal eukaryotes and the phylogenetic placement of new genes from other plant species.

Amino Acid Sequence↗
PubMed1999

Orthologs, paralogs and genome comparisons.

During the past decade, ancient gene duplications were recognized as one of the main forces in the generation of diverse gene families and the creation of new functional capabilities. New tools developed to search data banks for homologous sequences, and an increased availability of reliable three-dimensional structural information led to the recognition that proteins with diverse functions can belong to the same superfamily. Analyses of the evolution of these superfamilies promises to provide insights into early evolution but are complicated by several important evolutionary processes. Horizontal transfer of genes can lead to a vertical spread of innovations among organisms, therefore finding a certain property in some descendants of an ancestor does not guarantee that it was present in that ancestor. Complete or partial gene conversion between duplicated genes can yield phylogenetic trees with several, apparently independent gene duplications, suggesting an often surprising parallelism in the evolution of independent lineages. Additionally, the breakup of domains within a protein and the fusion of domains into multifunctional proteins makes the delineation of superfamilies a task that remains difficult to automate.

Animals↗
PubMed2026

Global lessons from antibiotic resistance: Metformin-hydrolysing genes in transposable elements, a new threat for type II diabetic patients?

OBJECTIVES: To investigate the evolutionary origin, genomic mobility, and potential dissemination of metformin-hydrolysing genes (mfmAB), and to assess whether environmental selection by metformin pollution may drive the emergence of transferable pharmaceutical-degrading traits analogous to antibiotic resistance. METHODS: Large-scale comparative genomics was performed using publicly available bacterial genomes carrying mfmAB homologs. Phylogenomic reconstruction, average nucleotide identity analysis, genomic context comparison, plasmid characterization, and insertion sequence mapping were used to infer evolutionary history and identify mechanisms of horizontal gene transfer. RESULTS: mfmAB homologs were identified in twelve Aminobacter and three Pseudomonas genomes within a conserved ∼8.2 kb gene cluster. Phylogenomic analyses showed that metformin-degrading capacity emerged independently in multiple Aminobacter lineages across distinct continents, consistent with convergent evolution under anthropogenic selective pressure. Genomic comparisons indicated a chromosomal origin of mfmAB, followed by mobilization onto conjugative plasmids through IS1182-mediated transposition. In Pseudomonas, additional IS3/IS6-mediated transposition events integrated mfmAB into diverse plasmid backbones, frequently within composite transposons also encoding guanylurea and biguanide degradation pathways (guuH, bguH). These findings reveal a dynamic modular assembly of metabolic functions facilitating adaptation to pharmaceutical pollutants. CONCLUSIONS: Metformin pollution appears to promote the emergence and mobilization of pharmaceutical-degrading genes through mechanisms paralleling antibiotic resistance evolution. Although no clinical impact has yet been demonstrated, the potential spread of such genes into human-associated microbiomes and their possible co-selection with antibiotic resistance determinants represent an emerging One Health concern. Environmental surveillance of pharmaceutical-degrading genes is warranted to anticipate future threats to drug efficacy.

Convergent evolution↗
PubMed2004

Structure and molecular phylogeny of sasA genes in cyanobacteria: insights into evolution of the prokaryotic circadian system.

Cyanobacteria are the simplest organisms known to have a circadian system. In addition to the three well-studied kai genes, kaiA, kaiB, and kaiC, an important element of this system is a two-component sensory transduction histidine kinase sasA. Using publicly available data of complete prokaryotic genomes, we performed structural and phylogenetic analyses of the sasA genes. Results show that this gene has a triple-domain structure, and the domains are under different selective constraints. The sasA gene originated in cyanobacteria probably through the fusion of the ancestral kaiB gene with a double-domain, two-component sensory transduction histidine kinase. The results of the phylogenetic analyses suggest that sasA emerged before the kaiA gene, about 3,000-2,500 MYA, and has evolved in parallel with the evolution of the kaiBC cluster. The observed concordant patterns of the sasA and kaiBC evolution suggest that these genes might compose an ancient KaiBC-SasA-based circadian system, without the kaiA gene, and that such a system still exists in some unicellular cyanobacteria.

Amino Acid Sequence↗
PubMed1989

The evolution of complex sensory systems in mammals.

Much of the forebrain of many extant species of mammals appears to be sensory-perceptual in nature. Thus, much of the forebrain, especially the dorsal thalamus and neocortex, consists of nuclei and areas that are parts of complex systems that analyze sensory information and allow behavior to be guided by accurate inferences about the external world. Since mammals vary tremendously in brain size, they vary in the amount of tissue devoted to sensory processing. In addition, mammals vary in the sizes and numbers of processing nuclei and areas, and in how neurons and neuron groups (modules) are differentiated within such structures. Sensory-perceptual systems with more, larger and more differentiated parts may allow more stimulus parameters to be considered, experience to play a greater role, and speed calculations through increased parallel processing. The evolution of species differences in brain size, the sizes of individual parts, and internal structure of these parts are potentially understandable within a theoretical framework of gradual modifications of developmental processes. In addition to changes in the generation and specialization of neurons, alterations in the developmental timing that modify internal and external influences on neuron activity patterns seem to have a major role in the construction and maintenance of organization in the nervous system. Because similar selection pressures may arise over and over again and the mechanisms for producing changes may be few, similar changes in the nervous system are likely to occur in independent lines of evolution. It is uncertain how new cortical areas and nuclei evolve. Comparative studies suggest that: (1) all mammals have a few basic sensory areas and nuclei in common, (2) the number of areas and nuclei has increased independently in several lines of mammalian evolution, and (3) new areas have been added to the middle levels of cortical processing sequences. New areas and nuclei may have evolved as a result of sudden duplications and/or by the process of single areas or nuclei gradually differentiating into two or more areas or nuclei. The process of gradual differentiation may have involved the initial step of differentiating functionally distinct classes of cells that are mixed in a representation, followed by the local groupings of such cells into functionally distinct sets, and finally the fusion of cell groups of the same types to form separate representations.

Afferent Pathways↗
PubMed2004

Repeated evolution of limblessness and digging heads in worm lizards revealed by DNA from old bones.

The evolutionary relationships of the burrowing amphisbaenians ('worm lizards') have long been controversial for several reasons: the rarity of museum specimens available for study, highly derived morphological conditions that can confound comparative studies and difficulty in obtaining tissues for molecular phylogenetic studies because of their secretive habits in the wild. We present a phylogenetic analysis of two nuclear genes obtained from both fresh tissues and museum specimens of worm lizards. We achieved sufficient taxonomic sampling for analysis by extracting DNA from museum specimens using a modified forensics protocol. Results show the limbless Rhineuridae to be the most basal lineage, whereas the limbed Bipedidae occupy a more derived position as the sister-taxon to a Trogonophidae-Amphisbaenidae clade. This pattern of relationships indicates widespread morphological convergence within the group, including three independent incidences of limb loss. Convergence in skull shape and scalation is also prevalent. Mosaic evolution in the skull versus postcranial skeleton parallels that seen in snake evolution.

Animals↗
PubMedDate not supplied

[Correlation between E.N.G. changes and the evolution of the hematic constants in patients under prolonged hemodialysis and renal transplantation].

An evolutive study of the E.N.G. on 25 patients affected of chronic renal failure (c.r.f.) in their previous periods and during the dialysis programme was developed. At the same time a large study on various serum changes was carried on. It is observed that the motor conduction velocity (M.C.V.) shows a decreasing evolution during dialysis, which mathematical patters is a branch of an equilateral hyperbola, of equation: (see article) The Na and K evolutive curves are also significatively fitted to the same mathematical pattern. It is observed a direct and inverse lineal correlation between M.C.V. values and those ones of the Na and K respectively, with p less than 0,05 and p less than 0,01. It is not observed any correlation of significatively value with the other serum parameters studied (R.A., Cl, Urea, Total proteins, Hematocrit, Ca, P, Creatinine, fluids and acid-base equilibrium). After a renal transplantation the M.C.V. presents a growing trayectory of the same mathematical pattern described before, reaching normal values about a year post-transplantion. The levels of Sodium serum follow a parallel trayectory than that one of the M.C.V. The recovery of the remainders serum parameters after renal transplantion occour during the first week, except for the hematocrit. It only remains a parallelism between the evolutive changes of M.C.V./Natremia during dialysis stage and after renal transplantion. These results seem to show a close dependence between variation of M.C.V. and Natremia. The hipoxia role over the sodium pump and the consequent variations of Natremia are discussed.

Blood Chemical Analysis↗
PubMed2005

Morphological evolution of the lizard skull: a geometric morphometrics survey.

Patterns of diversity among lizard skulls were studied from a morphological, phylogenetic, and functional perspective. A sample of 1,030 lizard skulls from 441 species in 17 families was used to create a lizard skull morphospace. This morphospace was combined with a phylogeny of lizard families to summarize general trends in the evolution of the lizard skull. A basal morphological split between the Iguania and Scleroglossa was observed. Iguanians are characterized by a short, high skull, with large areas of attachment for the external adductor musculature, relative to their sister group. The families of the Iguania appear to possess more intrafamilial morphological diversity than families of the Scleroglossa, but rarefaction of the data reveals this to be an artifact caused by the greater number of species represented in Iguanian families. Iguanian families also appear more dissimilar to one another than families of the Scleroglossa. Permutation tests indicate that this pattern is real and not due to the smaller number of families in the Iguanidae. Parallel and convergent evolution is observed among lizards with similar diets: ant and termite specialists, carnivores, and herbivores. However, these patterns are superimposed over the more general phylogenetic pattern of lizard skull diversity. This study has three central conclusions. Different clades of lizards show different patterns of disparity and divergence in patterns of morphospace occupation. Phylogeny imposes a primary signal upon which a secondary ecological signal is imprinted. Evolutionary patterns in skull metrics, taken with functional landmarks, allow testing of trends and the development of new hypotheses concerning both shape and biomechanics.

Animals↗
PubMedDate not supplied

[Left ventricular mechanics in Chagas' disease and primary dilated myocardiopathies. A hemodynamic study].

The evolution of several mechanical parameters of left ventricular function was studied in 32 control subjects, 171 chronic chagasic and 60 primary dilated cardiomyopathy patients, which were submitted to an extensive invasive and non-invasive protocol. Preload and afterload (end-diastolic and end-systolic stress), contractile status (ejection fraction), the magnitude (mass/index) and adequacy of hypertrophy (mass/volume ratio) and afterload (systolic stress/volume ratio) were derived from the invasive explorations. There was an increased afterload in 25% of chronic chagasic patients without other evidence of early myocardial damage, which was accompanied by signs of inadequate hypertrophy. Both findings increased further with the progression of the disease. Systolic performance was initially preserved, but showed a progressive depression paralleling the clinical evolution. Patients with dilated cardiomyopathy showed a mechanical profile similar to chagasic patients with advanced degree of myocardial damage. The hemodynamic determination of mass index, mass/volume ratio, end-systolic and end-diastolic stress seem to be the best parameters for detection of early abnormalities in loading conditions of the heart in chronic Chagas, disease, and for indication and evaluation of the results of vasodilator therapy in both groups of patients.

Adult↗
PubMed2003

The evolution of developmental mechanisms.

Over the past two to three decades, developmental biology has demonstrated that all multicellular organisms in the animal kingdom share many of the same molecular building blocks and many of the same regulatory genetic pathways. Yet we still do not understand how the various organisms use these molecules and pathways to assume all the forms we know today. Evolutionary developmental biology tackles this problem by comparing the development of one organism to another and comparing the genes involved and gene functions to understand what makes one organism different from another. In this review, we revisit a set of seven concepts defined by Lewis Wolpert (fate maps, asymmetric division, induction, competence, positional information, determination, and lateral inhibition) that describe the characters of many developmental systems and supplement them with three additional concepts (developmental genomics, genetic redundancy, and genetic networks). We will discuss examples of comparative developmental studies where these concepts have guided observations on the advent of a developmental novelty. Finally, we identify a set of evolutionary frameworks, such as developmental constraints, cooption, duplication, parallel and convergent evolution, and homoplasy, to adequately describe the evolutionary properties of developmental systems.

Animals↗