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Results for “Compensatory Evolution”

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PubMed1992

Interaction between verbal and gestural language in progressive aphasia: a longitudinal case study.

The objective of this longitudinal study is to investigate the on-line interaction between praxis and linguistic abilities in a progressive aphasia case. During 3 years of evolution, procedural discourse of a progressive aphasic patient was videotaped five times, allowing us to analyze the progression of both language and gestural production as well as the interaction between these two. We anticipated that, in the absence of apraxia, the patient would compensate for her speech deficit by producing progressively more and more meaningful gestures. Our compensatory hypothesis was confirmed but the compensation was not as efficient as one would expect given the absence of apraxia. With the progression of the speech deficit, the patient could not replace some verbs by pantomimes that were otherwise accompanying her discourse in the preceding testing sessions. We suggest that such a compensatory ability may constitute one important characteristic of the progressive aphasia syndrome.

Aphasia↗

PubMed1976

The differential development of the hominid pelvis.

The peculiarly shaped hominid pelvis represents the total response to the diverse forces which have moulded its structure, these being requirements for efficient bipedalism and parturition. In some respects the structural requirements of these unrelated functions have been in conflict. In these instances the morphological response to the dominant requirement, viz. bipedalism, is clearly discernible, while the changes subserving the needs of parturition are seen as compensatory modifications, the greater emphasis of which is responsible, in part, for pelvic sexual dimorphism in the female. Total pelvic architecture is thus a mosaic constituted by the aggregate of differential responses to different functional goals.

Adolescent↗

PubMed1987

Ecological compensation--a complication for testing life-history theory.

Mortality, growth and birth rates cannot vary independently in stable populations, environmental change of one variable must be accompanied by compensatory variation of another. Ecological compensation is recognized if the stable populations are genetically identical. Ecological compensation, if it operates, constrains the direction of evolutionary change, and predictions that ignore it may be in error.

Adaptation, Physiological↗

PubMed1989

Molecular evolution of the small subunit of ribulose bisphosphate carboxylase: nucleotide substitution and gene conversion.

The nucleotide sequences encoding the mature portion of 31 ribulose 1.5-bisphosphate carboxylase small subunit (SSU) genes from 17 genera of plants, green algae and cyanobacteria were examined. Among the 465 pairwise sequence comparisons, SSU multigene family members within the same species were more similar to each other in nonsynonymous or replacement nucleotide substitutions (RNS) than they were to SSU sequences in any other organism. The concerted evolution of independent SSU gene lineages within closely related plant species suggests that homogenization of RNS positions has occurred at least once in the life of each genus. The rate of expected RNS among mature SSU sequences was calculated to be 1.25 X 10(-9)/site/yr for the first 70 million years (MY) of divergence with a significant slowing to 0.13 X 10(-9)/site/yr for the next 1,400 MY. The data suggest that mature SSU sequences do not accumulate more than 20% differences in the RNS positions without compensatory changes in other components of this enzyme system. During the first 70 MY of divergence between species, the rate of expected synonymous or silent nucleotide substitutions (SNS) is approximately 6.6 X 10(-9)/site/yr. This is five times the RNS rate and is similar to the silent rate observed in animals. In striking contrast, SNS and RNS do not show this correlation among SSU gene family members within a species. A mechanism involving gene conversion within the exons followed by selection for biased gene conversion products with conservation of RNS positions and divergence of SNS positions is discussed. A SSU gene tree based on corrected RNS for 31 SSU sequences is presented and agrees well with a species tree based on morphological and cytogenetic traits for the 17 genera examined. SSU gene comparisons may be useful in predicting phylogenetic relationships and in some cases divergence times of various plant, algal and cyanobacterial species.

Amino Acid Sequence↗

PubMed1978

Intracranial pressure reserve testing. Initial clinical observations.

Sequential subdural injections of fluid through an intracranial pressure (ICP) monitoring cup catheter have been employed to measure "ICP reserve" in a series of 136 determinations in 30 patients over a total of 155 days of recordings. This dynamic method of quantitating the brain's ability to adapt to increased intracranial volume tests the brain's compensatory mechanisms over a five-minute time span. The test, incorporating several safety features, has been found to be reliable, safe, and well tolerated. A series of observations have been made using this test in patients with subdural drains and in response to fluid, mannitol, and dexamethasone therapy. Deteriorating ICP reserve gave early warning of the need for reoperation for postoperative hematoma, massive brain swelling, or cystic reaccumulation. Intracranial pressure reserve testing also quantitated the evolution of postoperative brain edema. Changes in ICP reserve could be detected as much as 48 hours before changes in baseline ICP and as much as 72 hours before clinical deterioration was evident.

Brain↗

PubMed1987

[Original adaptive characters of intestinal Digenea of Sarpa salpa (Teleostei, Sparidae) and their interpretation in terms of evolution].

In the family Sparidae, the genus Sarpa is distinguished by a few characteristics: monospecificity, vegetarian diet and wide geographical distribution. The helminth fauna of Sarpa salpa is also very original. Indeed, the digenean parasites of this Teleostean fish are essentially classified into two families restricted to this fish. In the present paper, the author redescribes Mesometra orbicularis, M. brachycoelia, Centroderma spinosissima, Elstia stossichianum, Wardula capitellata (family Mesometridae) together with Robphildollfusium fractum (family Robphildollfusidae). Various original and yet unknown features are pointed out. Among these unusual structures, several correspond to adaptive characteristics favouring the settlement of the Digenean on the peculiar digestive gut wall of this herbivorous fish. Indeed, the intestinal mucous membrane of Sarpa salpa exhibits very few villi giving it an unusual smooth aspect. Therefore, the Mesometridae which always have just a single sucker (monostomatous) have selected a new kind of compensatory adhesive structure. Sometimes, the anterior end of the body becomes a sucker due to the particular distribution of the muscle strings; in other examples, the whole body becomes a sucker and its edges become considerably thinner to improve the tightness of the adhesive system. Other original anatomical features have been selected to allow survival in a medium rich in plant detritus. So, in the oral sucker crests ornemented by numerous sclerous denticles seem to act as a microfilter for the intestinal chyme in which plant fibres predominate. The original pharynx seems to act as a suction-force pump. The excretory system, which is of a reticular type, penetrates the whole parenchyma and this could be a response to huge intestinal fermentations. The Digenea of Sarpa salpa are not interpreted by the author as true parasites but as endocommensal symbionts. These inquiline species are not immunogenic, or at least only slightly so, since they do not feed upon the host itself but upon its intestinal chyme. In most cases this results in a high parasite density (post larvae and adults) together with a cohabitation of the various species along the various intestinal segments. Coexistence of several species, systematically very close, evidently raises the question of their reproductive isolation. The author proposes an answer founded upon data of allopatric speciation.

Adaptation, Physiological↗

PubMed1991

Reconstruction and analysis of human Alu genes.

The existing classification of human Alu sequences is revised and expanded using a novel methodology and a larger set of sequence data. Our study confirms that there are two major Alu subfamilies, Alu-J and Alu-S. The Alu-S subfamily consists of at least five distinct subfamilies referred to as Alu-Sx, Alu-Sq, Alu-Sp, Alu-Sc, and Alu-Sb. The Alu-Sp and Alu-Sq subfamilies have been revealed by this study. Alu subfamilies differ from one another in a number of positions called diagnostic. In this paper the diagnostic positions are defined in quantitative terms and are used to evaluate statistical significance of the observed subfamilies. Each Alu subfamily most likely represents pseudogenes retroposed from evolving functional source Alu genes. Evidence presented in this paper indicates that Alu-Sp and Alu-Sc pseudogenes were retroposed from different source genes, during overlapping periods of time, and at different rates. Our analysis also indicates that the previously identified Alu-type transcript BC200 comes from an active Alu gene that might have existed even before the origin of dimeric Alu sequences. The source genes for Alu pseudogene families are reconstructed. It is assumed that diagnostic differences between reconstructed source genes reflect mutations that have occurred in true source Alu genes under natural selection. Some of these mutations are compensatory and are used to reconstruct a common secondary structure of Alu RNAs transcribed from the source genes. The biological function of Alu RNA is discussed in the context of its homology to the elongation-arresting domain of 7SL RNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1976

[Morphofunctional specialization of tissue components of the mammalian placenta and adaptational value in changes in the rate of their differentiation (evolutionary and clinical aspects)].

It has been shown that in the ontogenesis of human placenta there occur regular changes in the percentage of the villi of various calibre having different interrelationships between the trophoblast, the connective tissue stroma and the fetal vessel. The changes of the number of chorial villi affected by fibrinoid and containing blood vessels under the trophoblast in late toxicoses of women and the anemic syndrom are analyzed (treated and not treated groups of women suffering from different forms of toxicosis were compared). An increased amount of chorial villi having blood vessels under the trophoblast is noted which is a morphofunctional feature of compensatory-adaptational alterations. Possible ecologo-evolutionary approaches to clearing the biological significance of adaptational changes of morphogenesis of the human placenta in pathological pregnancy are shown by the example of the analysis of morphological peculiarities of the placenta of the dolphin.

Adaptation, Physiological↗

PubMed1990

Neurotransmitters and stress.

In this article definitions of stress and distress are proposed and the relationships between stress and activities of neurohormonal systems explored. The idea is developed that stress is a condition where expectations--whether genetically programmed, established by prior learning, or deduced from circumstances--do not match the current or anticipated perceptions of the internal or external environment, and this discrepancy between what is observed or sensed and what is expected or programmed elicits patterned, compensatory responses. Distress is viewed here as a form of stress characterized by specific behavioral and autonomic communicated signs, pituitary-adrenocortical and sympathoadrenomedullary activation, and a negative experience that motivates escape or avoidance. During stress, many body systems--including the sympathoadrenal, parasympathetic, and hormonal homeostatic systems--are activated or inhibited in primitively specific patterns regulated by physiological, biochemical, and psychological homeostats. Many of these patterns, which are at least partly inherited, can be understood teleologically on the basis of preservation of the internal environmental and natural selection in evolution.

Animals↗

PubMedDate not supplied

[Human hemoglobin: polymorphism, neutrality of variants, evolutionary aspect].

Integrated analysis of the polymorphism of human hemoglobin has been made using populational genetics, hematological, physiological, protein chemistry and molecular biology data. The known variants of human hemoglobin are conventionally classified as "widely common", "less common" and "rare", depending on their contribution to polymorphism. The importance of homeostasis and compensatory reactions for maintaining the resistance of the human body against mutant hemoglobins is emphasized. Hb D Punjab and Hb O Arab being relatively neutral, the genetic structure of populations may restrict their distribution. A hypothesis is put forward concerning the possible role of an increased local conformational mobility of protein in creating neutral protein variants. It is proposed to discriminate between truly neutral and pseudoneutral protein variants. In case of possible changes in the genetic and environmental factors, the former are not subject to selection, while the latter may be. Contribution to neutral evolution can be made only by truly neutral variants. In a compensated heterozygotic state the truly neutral and pseudoneutral variants may give rise to new functions and adaptively valuable properties in protein. The evolution of proteins is believed to proceed from a stage which is consistent with M. Kimura's concept of neutrality of protein polymorphism toward a stage which is consistent with the concept of selectionism. It is concluded, that the currently observed degree of polymorphism of human hemoglobin corresponds to the present stage of molecular evolution of the protein.

Biological Evolution↗

PubMed2025

Enhanced RNA replication and pathogenesis in recent SARS-CoV-2 variants harboring the L260F mutation in NSP6.

The COVID-19 pandemic has been driven by SARS-CoV-2 variants with enhanced transmission and immune escape. Apart from extensive evolution in the Spike protein, non-Spike mutations are accumulating across the entire viral genome and their functional impact is not well understood. To address the contribution of these mutations, we reconstructed genomes of recent Omicron variants with disabled Spike expression (replicons) to systematically compare their RNA replication capabilities independently from Spike. We also used a single reference replicon and complemented it with various Omicron variant Spike proteins to quantify viral entry capabilities in single-round infection assays. Viral entry and RNA replication were negatively correlated, suggesting that as variants evolve reduced entry functions under growing immune pressure on Spike, RNA replication increases as a compensatory mechanism. We identified multiple mutations across the viral genome that enhanced viral RNA replication. NSP6 emerged as a hotspot with a distinct L260F mutation independently arising in the BQ.1.1 and XBB.1.16 variants. Using mutant and revertant NSP6 viral clones, the L260F mutation was validated to enhance viral replication in cells and increase pathogenesis in mice. Notably, this mutation reduced host lipid droplet content by NSP6. Collectively, a systematic analysis of RNA replication of recent Omicron variants defined NSP6's key role in viral RNA replication that provides insight into evolutionary trajectories of recent variants with possible therapeutic implications.

SARS-CoV-2↗

PubMed1985

Plasticity of the central nervous system--a neurosurgeon's experience of cerebral compensation and decompensation.

Cerebral plasticity constitutes one of the most decisive factors in recovery and readaptation after cerebral lesions. In contrast to the considerable progress in current studies on normal neuronal plasticity including the idea of "l'homme neuronal", the concept of plasticity postulated by Albrecht Bethe in 1929 received little attention. The author, as a neurosurgeon, has tried to describe cranial morphological plasticity, morphological and functional plasticity in infantile encephalopathies and especially in hemiatrophic lesions. It is supposed that a true morphological substrate exists due to compensatory hyperplasia of the uninvolved hemisphere. Modern neurosurgical techniques have demonstrated that the functional plastic capacity is much larger than has been supposed, even in the elderly. Some aspects of the mechanisms of compensation and decompensation of cortical and subcortical structures as well as of the central regulation systems are discussed. The full extent of the amazing recovery and functional reorganization is reached by plastic capacity, personal motivation, adequate training and sufficient time. The contribution ends with an exposition of a personal philosophy concerning psycho-somatic dualism, the body-mind problem, the future of the human brain and the ethical outlook, based on the progressive biological evolution of the basal neocortex and the immanent functional development (H. Spatz).

Adaptation, Physiological↗

PubMed2026

Gene expression is stable despite widespread cis and trans regulatory divergence in Saccharomyces yeasts.

Regulatory evolution can alter phenotypes, but cis- and trans-regulatory mechanisms may also diverge extensively while total transcript abundance remains stable. Comparisons of parental expression with allele-specific expression in F1 hybrids provide a framework for separating cis- and trans-regulatory effects because both parental alleles are measured in a shared trans-regulatory environment. Here, we analyzed RNA sequencing data from Saccharomyces cerevisiae, Saccharomyces paradoxus, and their F1 hybrid. Regulatory divergence was widespread, with 61.3% of tested orthologs showing significant divergence in at least one cis or trans component. However, hybrid expression remained largely conserved, with 81.6% of genes not significantly different from either parent. Compensatory cis-trans divergence predominated over reinforcing divergence, consistent with widespread buffering of transcript abundance. To connect genome-wide patterns to mechanism, we analyzed the strongly cis-diverged locus LYS2 and found species differences in promoter architecture, including an S. cerevisiae-specific AT-rich insertion, altered spacing among candidate regulatory features, and a promoter-proximal TATA-like element unique to S. cerevisiae. Sequence-based nucleosome prediction suggests that these differences create a broader promoter-proximal nucleosome-depleted region in S. cerevisiae than in S. paradoxus. We also quantified allele-resolved intron retention and found that splicing was broadly conserved, with only rare locus-specific hybrid-associated shifts. Together, these results show that regulatory divergence is widespread but often buffered in the hybrid, whereas post-transcriptional divergence is comparatively limited.

Gene expression↗

PubMed1989

Sequences similar to genes for two mitochondrial proteins and portions of ribosomal RNA in tandemly arrayed 6-kilobase-pair DNA of a malarial parasite.

Erythrocytic stages of mammalian malarial parasites contain acristate mitochondria whose functions are not well understood. Moreover, little is known about the genome of these organelles. We have previously reported that all species of malarial parasites examined contain highly conserved, tandemly arrayed DNA with a unit length of about 6.0 kb that is transcribed into discrete RNA molecules in erythrocytic stages. We now report the complete DNA sequence of the 5984-bp repeating unit of Plasmodium yoelii, a rodent parasite. Two slightly overlapping regions transcribed into large RNA molecules were found to have significant DNA and protein sequence similarity with mitochondrion-coded proteins, cytochrome c oxidase subunit I and cytochrome b. Significant sequence similarity with other mitochondrial protein genes could not be detected. Ribosomal RNA (rRNA)-like genes were not detected in this sequence either. However, two regions, 82 and 50 nucleotides long, specified by different strands, were found to have extensive similarity with the highly conserved central loop of the peptidyl transferase domain of the large rRNA of Escherichia coli, mitochondria, and chloroplasts. Compensatory nucleotide substitutions were present in these regions, so that the predicted secondary structure was not affected. Functional utilization of these regions, if it exists, could argue for a trans-associative origin of rRNA. In organization, size and sequence, the tandem arrays of 6.0 kb malarial DNA appear to be a very unusual form of mitochondrial DNA.

Acyltransferases↗

PubMedDate not supplied

[The clinical picture of spinal cord tumors with different histostructures in children].

An analysis into the results of treatment accorded to 101 sick children wiht tumours of the spinal cord evidences that the clinical picture of this pathology is distinguished by a number of features that depend on the histological structure, high compensatory potentialities and extraordinary plasticity of the child's spinal cord and vertebral column. In this connection of prime importance becomes the significance of assessing the data derived from a comprehensive examination, due consideration being given to the age-specific features of the patients. As concerns their incidence in children first and foremost are tumours of the glial series, distinguished by a comparatively mild course of the disease, paucity of focal and conduction symptomatology that is incongrous with the extent of the lesion involving the spinal cord both along its vertical and transverse section. The tumours of the meningovasal series are of rare occurrence, their salient feature being malignant evolution of the affection with extradural localization. Notwithstanding their intensive growth the heterotopic tumours cause in a number of cases some difficulty in the topicodiagnostic respect, this being due to a well-pronounced memingeal syndrome with an extremely poor focal symptomatology. An early surgical and radiation treatment of tumours in the glial series renders a realively good curative effect with partial restoration of disturbed functions in the early and late post-treatment periods.

Adolescent↗

PubMed2026

Gene expression is stable despite widespread cis and trans regulatory divergence in Saccharomyces yeasts.

Regulatory evolution can alter phenotypes, but cis- and trans-regulatory mechanisms may also diverge extensively while total transcript abundance remains stable. Comparisons of parental expression with allele-specific expression in F1 hybrids provide a framework for separating cis- and trans-regulatory effects because both parental alleles are measured in a shared trans-regulatory environment. Here, we analyzed RNA sequencing data from Saccharomyces cerevisiae, Saccharomyces paradoxus, and their F1 hybrid. Among the 4,164 genes with sufficient allele-specific support for strict classification, 2,134 (51.2%) showed detectable cis and/or trans regulatory divergence. However, hybrid expression remained largely conserved, with 81.5% of genes not significantly different from either parent. Compensatory cis-trans divergence predominated over reinforcing divergence; cross-replicate estimation reduced the apparent magnitude of this excess, but opposite-sign effects remained predominant in all 20 non-overlapping replicate comparisons. To connect gene expression to genome sequence, we analyzed the strongly cis-diverged locus LYS2 and found species differences in promoter architecture, including an S. cerevisiae-specific AT-rich insertion, altered spacing among candidate regulatory features, and a promoter-proximal TATA-like element unique to S. cerevisiae. Sequence-based nucleosome prediction suggests that these differences create a broader promoter-proximal nucleosome-depleted region in S. cerevisiae than in S. paradoxus. We also quantified allele-resolved intron retention and found that allele-resolved intron retention was broadly conserved, with only rare locus-specific hybrid-associated shifts. Together, these results show that regulatory divergence is widespread but often buffered in the hybrid, whereas intron-retention divergence is comparatively limited.

Saccharomyces↗

PubMed1986

Temporal evolution of altered islet neurotransmitter sensitivity after VMH lesion.

It has been suggested that increased insulin secretion after ventromedial hypothalamic (VMH) obesity is mediated by decreased sympathetic and increased parasympathetic neural input. The evolution of pancreatic islet adaptation was studied from 1 to 130 days after VMH lesion in rats by assessing the sensitivity of insulin secretion from incubated isolated islets to 10 mM glucose and selected acetylcholine and norepinephrine concentrations. Insulin secretion in response to glucose increased by 1 day, reaching a twofold plateau from 7 to 130 days. Sensitivity to norepinephrine increased by 1 day, whereas sensitivity to acetylcholine decreased by 2 days, and both remained altered up to 130 days. These data suggest that elevated plasma insulin concentrations characteristic of VMH obesity were associated with increased insulin secretion in response to glucose before decreased sensitivity to acetylcholine and concurrent with increased sensitivity to norepinephrine. We conclude that these compensatory responses, which shift the islet to a new operating point secondary to altered neural input, are essential to pancreatic adaptation in VMH obesity.

Acetylcholine↗

PubMed2026

The Convergence of Antimicrobial Resistance and Virulence in Streptococcus pneumoniae: A Molecular and Clinical Perspective.

Antimicrobial resistance (AMR) and virulence have traditionally been viewed as competing traits in bacterial evolution due to fitness costs. However, Streptococcus pneumoniae has emerged as a paradigm of successful coevolution, with multidrug-resistant clones simultaneously maintaining or enhancing pathogenic potential. This review examines the molecular mechanisms, epidemiological patterns, and clinical consequences of the convergence between AMR and virulence in Streptococcus pneumoniae. Resistance to β-lactams is driven by mosaic penicillin-binding protein genes (pbp1a, pbp2b, pbp2x), while macrolide resistance is mediated primarily by the erm(B) gene (MLS phenotype) and mef(A/E)-msr(D) genes encoding an efflux system. These determinants are frequently co-localized on integrative and conjugative elements, ICEs, (e.g., Tn916 family) within successful clonal complexes such as CC271/320 and lineages including ST320 and GPSC10. Contrary to the classical fitness cost hypothesis, compensatory epistasis, capsular recombination, metabolic adaptations, and intra-serotype phenotypic variation enable certain clones to combine high-level resistance to β-lactams, macrolides, and tetracyclines with enhanced colonization, biofilm formation, immune evasion, and invasive capacity. Post-pneumococcal conjugate vaccine (PCV) surveillance reveals the persistence and expansion of these high-risk lineages, contributing to treatment-refractory invasive pneumococcal disease (IPD), increased morbidity, and mortality. Although PCVs have reduced vaccine-type resistant strains in some settings, serotype replacement and emerging metabolic genotypes continue to drive adaptation. This review highlights the need for integrated genomic surveillance, novel therapeutics (e.g., omadacycline, lefamulin, endolysins), monoclonal antibodies, and next-generation vaccines targeting both resistance and conserved virulence determinants. A multifaceted strategy combining antimicrobial stewardship, strengthened surveillance, and innovative interventions is essential to curb the evolving threat of resistant and virulent S. pneumoniae.

Streptococcus pneumoniae↗