SEARCH · PubMed Health

Results for “coevolution”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

1,112 records · Page 62Linked to original sources

PubMed1993

[Theoretical analysis of some features of compensatory substitution in stem regions of transport RNA].

Some families of isoacceptor tRNAs were studies using VOSTORG software package for phylogenetic analysis. While analysing the evolutionary trees in was shown that the fixation of double substitutions AU<-->GC in spiral double-stranded regions passes two stages with intermediate station, such as non-canonical base pairs. In all the families studied double substitutions can be explained not only by passages through slightly deleterious GU pairs. Comparative analysis of B2-like repeats shown the absence of compensatory substitutions in the parts which are homologous to RNA stem regions. The data obtained let us assume that compensatory substitutions in the RNA helical regions represent an expressive example of non-directed adaptive molecular coevolution.

Animals↗

PubMed1996

[Evolution of cells].

Life has existed on earth for some 4 x 10(9) years. During most of this time, evolution took place at the level of cell evolution. The cells of presently existing organisms belong to two fundamentally different cell types, protocytes (of bacteria and archaea) and eucytes (of eukarya). Thanks to molecular phylogenetics, the path of evolution can now be traced back to its very beginnings, although the picture may be blurred by repeated horizontal gene transfer. A symbiogenetic origin of plastids and mitochondria is now very well documented, and it is being discussed also for some other constituents of eucytes, including even the cells nucleus. It could be demonstrated that not only did bacterial cells become incorporated into protoeucytes and transformed into organelles of their respective hosts, but also that endocytic eucytes have apparently been transformed to complex organelles by coevolution with host cells.

Animals↗

PubMed1996

Emended description of Mazamastrongylus peruvianus (Nematoda:Trichostrongylidae), with comments on the relationships of the genera Mazamastrongylus and Spiculopteragia.

Resurrection of Mazamastrongylus as proposed by Jansen (1986) was validated and placement of Mazamastrongylus peruvianus in this genus was confirmed, based on characters of the synlophe, copulatory bursa, and spicules. The cervical synlophe consists of a strongly tapering pattern and prominent "hood ridges" at the level of the excretory pore; there are 40 ridges at the midbody of males. The bursa is of the 2-2-1 type, with rays 2 and 3 parallel and rays 4 and 5 of near equal length and only slightly divergent at the tips. The spoon-shaped dorsal process of the spicules, typical of M. peruvianus and other species of Mazamastrongylus is postulated as a synapomorphy for the genus. The genera Mazamastrongylus, Spiculopteragia, and Sarwaria are considered to be independent based on characters of the synlophe, spicules, and copulatory bursa. Host and geographic distributions for species of Mazamastrongylus appear to be consistent with a history of coevolution and colonization and relationships for M. peruvianus may parallel the pattern postulated for species of Nematodirus in cervids and camelids in the Neotropics.

Animals↗

PubMedDate not supplied

[Greenhouse effect and probable prospects: global catastrophe or optimization of the biosphere?].

Author pay attention to polyvariantness of expectative consequences of hotbed effect, to evolution-biological aspect of problem, and to evolution prognosis difficulties. The perspective of biosphere and mankind survival is mutual adaptation in coevolution process. Creation of complete biological evolution theory is becoming more and more urgent. Evolution prognosis and biosphere management will be realized on evolution theory base.

Biological Evolution↗

PubMed1996

[The nature of personality: a co-evolutionary perspective].

Personality psychologists' attempts to explain human diversity have traditionally focused upon processes of person-situation interaction, and genotype-environment interaction. The great variability of genotypes and environments within cultures has remained unexplained in these efforts. Which processes may be responsible for the genetic and environmental variability within cultures? Answers to this question are sought in processes of genetic-cultural coevolution: mutation and sexual recombination of genes, innovation and synthesis of memes (units of cultural transmission), genotype-->environment and meme-->environment effects, and frequency-dependent natural and cultural selection. This twofold evolutionary explanation of personality differences within cultures suggests that a solid foundation of personality psychology requires bridging biology and cultural science.

Biological Evolution↗

PubMed1996

A base substitution in the amino acid acceptor stem of tRNA(Lys) causes both misacylation and altered decoding.

In 1984, our laboratory reported the characterization of the first misacylated tRNA missense suppressor, a mutant Escherichia coli lysine tRNA with a C70 to U base change in the amino acid acceptor stem. We suggested then that the suppressor tRNA, though still acylated to a large extent with lysine, is partially misacylated with alanine. The results reported in this article demonstrate that is the case both in vitro and in vivo. For the in vitro studies, the mutant tRNA species was isolated from the appropriate RPC-5 column fractions and shown to be acylatable with both lysine and alanine. For the in vivo demonstration, use was made of a temperature-sensitive alaS mutation, which results in decreasing acylation with Ala as the temperature is increased, resulting ultimately in lethality at 42 degrees C. The alaSts mutation was also used to demonstrate that the ability of the same missense suppressor, lysT(U70), to suppress a trpA frameshift mutation is not affected by the Ala-acylation deficiency. We conclude that the misacylation and altered decoding are two independent effects of the C70 to U mutation in tRNA(Lys). The influence of an alteration in the acceptor stem, which is in contact with the large (50S) ribosomal subunit, on decoding, which involves contact between the anticodon region of tRNA and the small (30S) ribosomal subunit, may occur intramolecularly, through the tRNA molecule. Alternatively, the U70 effect may be accomplished intermolecularly; for example, it may alter the interaction of tRNA with ribosomal RNA in the 50S subunit, which may then influence further interactions between the two subunits and between the 30S subunit and the anticodon region of the tRNA. Preliminary evidence suggesting some form of the latter explanation is presented. The influence of a single nucleotide on both tRNA identity and decoding may be related to the coevolution of tRNAs, aminoacyl-tRNA synthetases, and ribosomes.

Acylation↗

PubMed1997

In search of a bacterial species definition.

The bacterial species concept was examined within the framework of plant and animal associated alpha-2 proteobacteria, taking into consideration the phylogenetic, taxonomic and biological approaches as well as the microbiologists' perception. The virtue of the phylogenetic approach is that it gives an evolutionary perspective of the bacterial lineage; however the methods used possess low resolution for defining species located at the terminal branches of the phylogenetic trees. The merit of the taxonomic approach is that species are defined on the basis of multiple characteristics allowing high resolution at the terminal branches of dendograms; its disadvantage is the inaccuracy in the earlier nodes. On an individual level, the qualitative biological characteristics used for the definition of species frequently reveal shortcomings because many of these properties are the result of coevolution, parallel evolution or the horizontal transfer of genes. Nevertheless, when considered together with the phylogenetic and taxonomic approaches, important uncertainties are discovered: these must be weighed if a practical definition of bacterial species is conceived. The microbiologists' perception is the criterion expressed by a group of sponsors who, based on scientific and practical grounds, propose a new bacterial species. The success of this new proposal is measured by its widespread acceptance and its permanence. A difficult problem concerned with defining bacterial species is how to distinguish if they are independent evolutionary units or if they are reticulate evolutionary units. In the first case the inherence is vertically transmitted as a result of binary fission and clonal expansion. This may be the case of some animal cell associated bacteria in which recombination appears to be precluded or exceptional. In the second case adaptive changes occurring within an individual can be horizontally transferred to many or all group members. This seems to be the condition of many intestinal and plant associated bacteria. Genetic drift and speciation in clonal bacteria will depend almost exclusively on mutation and internal genetic rearrangement processes, whereas speciation in reticulate bacteria will depend not only on these processes but in their genetic interactions with other bacterial strains. This uncertainty, which corresponds to the evolutionary process, is at the same time one of the key factors in defining a bacterial species.

Bartonella↗

PubMedDate not supplied

[Parasitic systems under the conditions of human pressures (the problems of parasitic contamination)].

Foundations of the Parasitic Contamination (PC) conception being considered as an element of biological contamination and manifested itself in urbanized ecosystems under an influence of diversiform ecological (amenable to anthropopressure) and socio-economical factors are presented. PC is regarded as the "superthreshold" contamination exceeding the "natural background" (i.e. the parasitological situation outside urbanized ecosystems). As a rule, PC is accompanied with events as follow: an increase (often explosive in character) of hosts' number of all ranks, of vectors numbers and finally of parasites' numbers (parasitic expression); a partial replacement of parasite faunas (parasitic succession); a capture of new territories and hosts (parasitic expansion). As a rule, all processes run synchronously. They lead to disturbances of evolutionary generated relations (quantitative and qualitative ones) in parasitic systems and thereafter to changes in a tension of epidemic, epizootic and epiphytotic processes. It is assumed, that rates of evolutionary processes going in parasitic systems is increased at the recent historical stage. Their entropy character is being changed: they often transform from more of less regulated (balanced) processes, which were achieved in a long course of component coevolution, into chaotic (unbalanced) ones. It is stimulated with a powerful and at the same time differently vectored anthropogenic pressure onto parasitic system components. It promotes inhibition processes involved in generating of a natural parasite-host mutual adaptation.

Animals↗

PubMed1998

Host-mediated site segregation of ectoparasites: an individual-based simulation study.

Site segregation of coexisting ectoparasite species may result either from a direct interaction such as resource competition between them or from a host-mediated interaction. Here we present an individual-based model for the coevolution of 1 host and 2 parasite species to study this latter hypothesis. Parasite species are generalists at the start of the simulation and develop site specificities under the following assumptions. Parasite populations are not subject to resource limitations but are limited directly by host defense as predation. Hosts have 2 sites that need different defensive abilities to reduce their parasite burden. Parasites need to exhibit different evasive abilities to survive on different sites. Host grooming selects parasites for an increasing capability for evasion, whereas parasites select hosts for an increasing efficiency of grooming. Two trade-offs are incorporated into the model: one between host defensive abilities on the 2 sites, and another between parasite evasive abilities on the 2 sites. We conclude that, under these assumptions, the optimization of host defense and parasite evasion strategies may select ectoparasites for site segregation and this may stabilize the coexistence of parasite species.

Animals↗

PubMed1998

The origin and evolution of viruses (a review).

Viroids and prions might have existed early at the border of inanimate and living worlds. Most extant viruses can be characterized as derivatives of ancestors originating from episomal elements of prokaryotes (DNA phages) and later from eukaryotes. Retroviruses very likely originated from cellular retrotransposons. Retrograde evolution of some large viruses from obligatory intracellular bacteria is possible but the ontogenesis of extant bacteria does not include a viral form of existence (the filterable L forms are not viruses) and well-defined viruses do not regenerate back into vegetative bacterial forms. Biologists experimenting with the evolution of prokaryotic and eukaryotic ancient cells cannot ignore the earliest appearance of viruses within or outside the living matter. Viruses participated in and gave direction to the evolution and natural selection by coexisting with uni- and multicellular organisms for billions of years. The coevolution of viruses and their host cells is characterized by incessant attacks and counterattacks through gene rearrangements and mutations (induced in the virus by an immunological counterattack of the host or by transgression of species barriers by the virus) and recombinations. Recombinations occurred between viral and viral or viral and host genes. Acts of "molecular piracy" as practiced by ancient viruses endowed the virus with the expression of several host genes for the advantage of the virus in its replicative cycle and host-to-host spread. Probably the first immortalized and malignantly transformed cells were induced by viruses as viruses evolved anti-apoptotic measures. While infected cells resort to apoptotic death before the assembly of a new viral progeny, prominent are the anti-apoptotic measures viruses evolved in order to assure the completion of their full replicative cycle. Further, viruses may escape neutralization by host antibodies and may survive a counterattack by the host's T cells directed at virally infected cells of its own. Viruses may induce a form of tolerance and coexist with their host without inducing disease. Persistent and apparently or deceivingly apathogenic or even attenuated viral "quasi-species" populations may contain individual particles that regain virulence due to recombinations and/or gene rearrangements, especially when transgressing species barriers. Xenotropic viruses of animals may replicate in human cells and vice versa confounding experiments with xenotransplants or with use of veterinary viral vaccines for the treatment of human diseases.

Animals↗

PubMed2026

Ten millennia of purifying selection on HLA-B27 reveals an ancient epidemic-scale burden of spondyloarthritis in West Eurasia.

HLA-B27 exemplifies an evolutionary trade-off between protection against infection and susceptibility to inflammatory disease. To investigate its long-term population history, this study examined three HLA-B27-tagging variants-rs116488202, rs4349859, and rs116666910-in present-day populations from UK biobank and 1000 Genomes Project, and in 15,836 ancient West Eurasian individuals. The estimated frequency of HLA-B27 reached 49.0% approximately 8500 years before present, then declined progressively to 3.9% in the present-day reference population. Comparison with genome-wide association study (GWAS) data for ankylosing spondylitis (AS) showed that HLA-B27-linked alleles conferring increased disease risk had negative selection coefficients, indicating sustained selection against HLA-B27 over the past 10,000 years. The decline coincided with major Holocene changes in settlement and subsistence patterns, microbial exposure, and enteric infection, which may have increased the inflammatory costs of HLA-B27. Because previous paleopathological studies have largely been limited to identifying advanced skeletal manifestations of AS, this ancient genetic study may provide currently the most sensitive population-level record of an otherwise largely undetectable, epidemic-scale disease burden in antiquity. These findings support the hypothesis that HLA-B27-associated spondyloarthritis was sufficiently prevalent and severe to influence human evolution in prehistoric West Eurasia.

Humans↗

PubMed2025

ERCnet: Phylogenomic Prediction of Interaction Networks in the Presence of Gene Duplication.

Assigning gene function from genome sequences is a rate-limiting step in molecular biology research. A protein's position within an interaction network can potentially provide insights into its molecular mechanisms. Phylogenetic analysis of evolutionary rate covariation (ERC) in protein sequence has been shown to be effective for large-scale prediction of functional relationships and interactions. However, gene duplication, gene loss, and other sources of phylogenetic incongruence are barriers for analyzing ERC on a genome-wide basis. Here, we developed ERCnet, a bioinformatic program designed to overcome these challenges, facilitating efficient all-versus-all ERC analyses for large protein sequence datasets. We simulated proteome datasets and found that ERCnet achieves combined false positive and negative error rates well below 10% and that our novel "branch-by-branch" length measurements outperforms "root-to-tip" approaches in most cases, offering a valuable new strategy for performing ERC. We also compiled a sample set of 35 angiosperm genomes to test the performance of ERCnet on empirical data, including its sensitivity to user-defined analysis parameters such as input dataset size and branch-length measurement strategy. We investigated the overlap between ERCnet runs with different species samples to understand how species number and composition affect predicted interactions and to identify the protein sets that consistently exhibit ERC across angiosperms. Our systematic exploration of the performance of ERCnet provides a roadmap for design of future ERC analyses to predict functional interactions in a wide array of genomic datasets. ERCnet code is freely available at https://github.com/EvanForsythe/ERCnet.

Gene Duplication↗

PubMed2025

Evolutionary and Functional Analysis of Caspase-8 and ASC Interactions to Drive Lytic Cell Death, PANoptosis.

Caspases are evolutionarily conserved proteins essential for driving cell death in development and host defense. Caspase-8, a key member of the caspase family, is implicated in nonlytic apoptosis, as well as lytic forms of cell death. Recently, caspase-8 has been identified as an integral component of PANoptosomes, multiprotein complexes formed in response to innate immune sensor activation. Several innate immune sensors can nucleate caspase-8-containing PANoptosome complexes to drive inflammatory lytic cell death, PANoptosis. However, how the evolutionarily conserved and diverse functions of caspase-8 drive PANoptosis remains unclear. To address this, we performed evolutionary, sequence, structural, and functional analyses to decode caspase-8's complex-forming abilities and its interaction with the PANoptosome adaptor ASC. Our study distinguished distinct subgroups within the death domain superfamily based on their evolutionary and functional relationships, identified homotypic traits among subfamily members, and captured key events in caspase evolution. We also identified critical residues defining the heterotypic interaction between caspase-8's death effector domain and ASC's pyrin domain, validated through cross-species analyses, dynamic simulations, and in vitro experiments. Overall, our study elucidated recent evolutionary adaptations of caspase-8 that allowed it to interact with ASC, improving our understanding of critical molecular associations in PANoptosome complex formation and the underlying PANoptotic responses in host defense and inflammation. These findings have implications for understanding mammalian immune responses and developing new therapeutic strategies for inflammatory diseases.

Caspase 8↗

PubMed2026

Tree Killer, Qu'est-ce Que C'est? Insights From Forest Pathogen Genomes.

Forests are central to planetary health but are increasingly challenged by emerging diseases driven by climate change, global trade, and anthropogenic disturbance. Despite the apparent resilience of long-lived, genetically diverse tree hosts, forest ecosystems have repeatedly experienced landscape-level pathogen-driven transformations. Advances in genomics, transcriptomics, and functional biology have transformed our understanding of how fungal and oomycete pathogens interact with their hosts across a continuum of lifestyles, from saprotrophy and necrotrophy to biotrophy. Here, we synthesize insights from comparative and population genomics and functional studies across diverse forest pathosystems to examine the traits that characterize successful tree pathogens. We highlight how lifestyle plasticity, adaptations to woody tissues, vector-mediated transmission, and biotrophic stealth enable pathogens to colonize perennial hosts and persist over long temporal scales. We further examine how genome plasticity, hybridization, and horizontal gene transfer generate adaptive potential that often outpaces host evolutionary responses under current environmental change. Finally, we discuss emerging genomic tools, including biosurveillance, machine learning-based classification, and genome editing, that are beginning to link genotype to phenotype and inform assessments of disease risk. By integrating genomic, ecological, and evolutionary perspectives, this review outlines general principles governing forest pathogen success and identifies priorities for future research aimed at improving understanding, early detection, and management of forest diseases in a changing world.

Trees↗