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Results for “Parallel evolution”

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PubMed1976

Adjacent repeating units of Xenopus laevis 5S DNA can be heterogeneous in length.

The distribution of length heterogeneity in adjacent repeating units of X. laevis 5S DNA has been examined by "cloning" 5S DNA in bacteria. Fragments of 5S DNA produced by partial digestion with Hind III and containing 1, 4, and 5 repeating units have been inserted at the single Hind III site of the tetracycline-resistance plasmid, pSC101, and the hybrid plasmids cloned in E. coli. Adjacent 5S DNA repeats in the cloned multi-repeat fragments can differ in length. This finding rules out some mechanisms which have been proposed to account for the parallel evolution of tandem repeated DNAs. The results are consistent with an unequal crossing-over mechanism and place some constraints on the molecular processes in this recombinatory event.

Animals↗

PubMed1992

Follicle-stimulating hormone bioactivity in idiopathic normogonadotropic oligoasthenozoospermia: double-blind trial with gonadotropin-releasing hormone.

OBJECTIVE: To identify, among patients with idiopathic normogonadotropic oligoasthenozoospermia, those with low bioactive follicle-stimulating hormone (FSH), possibly because of inadequate gonadotropin-releasing hormone (GnRH) pulsatility, whose bioactive FSH and sperm could be improved by GnRH treatment. DESIGN: Randomized, double-blind, placebo-controlled trial with intranasal (IN) GnRH, followed by open GnRH treatment. SETTING: Outpatient endocrinology clinic. PATIENTS: Twenty-eight infertile men with idiopathic normogonadotropic oligoasthenozoospermia. INTERVENTIONS: Gonadotropin-releasing hormone or placebo was self-administered IN every 2 hours. MAIN OUTCOME MEASURES: Serum immunoreactive and bioactive FSH and semen analyses. RESULTS: Ten men showed a low basal FSH bioactive/immunoreactive ratio, which increased in 5 of them under GnRH without parallel sperm modification. Sperm improvements were observed in 10 patients with no parallel evolution of FSH bioactive/immunoreactive ratio. Unpredicted by sperm changes, three pregnancies developed on placebo and 5 on GnRH. CONCLUSIONS: Low bioactive FSH was not the cause of idiopathic normogonadotropic oligoasthenozoospermia in our patients and could not predict response to GnRH. Pulsatile GnRH did not improve sperm beyond random fluctuations.

Administration, Intranasal↗

PubMedDate not supplied

[Destructive polyarthritis in Behcet's disease. Apropos of a case and review of the literature].

The authors report a case of a 37 years old man with Behçet's disease since 7 years who develops a destructive chronic polyarthritis involving wrists, hands and one knee. The parallel evolution between recurrent orogenital ulceration and arthritis added to the absence of other associated destructive rheumatism permit to link this polyarthritis to Behçet disease. In spite of the few reports, the occurrence of destructive arthritis can't exclude absolutely the diagnosis of this affection.

Adult↗

PubMed1992

Search for the mechanism of toxicity of dioxins. A lesson in toxicology.

The development of modern toxicology was strongly influenced by parallel evolutions of sister disciplines as well as regulatory requirements. This led to an overemphasis of some areas of toxicology while other aspects of it experienced at least a temporary benign neglect. The author of this paper believes that the few and far between successes in elucidating the mechanism of toxicity of chemicals are related to this uneven approach to a very complex problem. Based on one of the most important and controversial contemporary issues in toxicology, viz. that of dioxins, it is argued that by a systematic step-wise use of methodologies borrowed from sister disciplines, our capabilities of elucidating the mechanism of action of toxicants can be considerably improved.

Animals↗

PubMed1976

Similarities and differences in the structure of X and Y chromosome rRNA genes of Drosophila.

In Drosophila melanogaster, the rRNA genes (rDNA) are clustered at single sites on two non-homologous chromosomes, the X and Y. Examination of the structure of X and Y rDNAs with restriction endonucleases reveals that the X rDNA contains repeating units not present in the Y. Such observations, as well as genetic evidence, illustrate difficulties with the hypothesis that recombination is the predominant mechanism preserving similarities between these two clusters maintained on different chromosomes. This raises the possibility that selection pressure has a significant role in maintaining the parallel evolution of these two separate but homologous redundant gene clusters.

Animals↗

PubMed1976

Role of major histocompatibility complex gene products in delayed-type hypersensitivity.

Sensitized thymus-derived (T) lymphocytes can transfer delayed-type hypersensitivity (DTH) to naive mice only if there is identity at the major histocompatibility complex (MHC). The MHC region responsible differs according to the antigen used for sensitization. For transfer of DTH to fowl gamma globulin identity at I-A is necessary; for dinitrofluorobenzene, however, identity at either K, D, or I region is sufficient. T cells of one genotype, sensitized in a chimeric environment, transferred DTH to both parental strains even though these were MHC incompatible. However T cells from F1 hybrid mice, sensitized not in the F1 but in one parental strain, transferred DTH only to that parental strain, not to the other, in contrast to F1 T cells sensitized in the F1 which could transfer DTH to both parental strains. Macrophages pulsed with antigen in vitro could be used to sensitize syngeneic or semi-allogeneic mice for the transfer of DTH. Transfer was, however, successful only in the strain syngeneic to that from which the macrophages were derived. Evidence is also presented that genetically low-responder mice can be made to exhibit DTH provided they are pretreated with cyclophosphamide two days before sensitization. When considered in toto these results strongly argue in favor of the notion that there are receptors on activated T cells which recognize antigenic determinants and MHC gene products. The implications of these findings are discussed in relation to the role of macrophages in antigen presentation and to the possible parallel evolution of MHC gene products and of T cell receptors for antigen.

Animals↗

PubMed1977

A systems-analytical approach to macro-evolutionary phenomena.

Two sets of evolutionary phenomena find no explanation through current theory. For the static phenomena (such as homology, homonomy, systematic weight, and "Type") there is no causal base, although these principles are responsible for all phenomena of predictable order in the living world. The dynamic phenomena (such as homodynamy, coadaptation, parallel evolution, orthogenesis, Cartesian transformation, typostrophy, hetermorphosis, systemic mutation, and spontaneous atavism) have no causal explanation, although they are responsible for all directed phenomena in macroevolution. These phenomena share one unifying principle which can be explained by a system theory of evolution based on, but extending, the current synthetic theory. This system theory envisages feedback conditions between genotype and phenotype by which the chances of successful adaptation increase if the genetic units, by insertion of superimposed genes, copy the functional dependencies of those phene structures for which they code. This positive feedback of the adaptive speed (or probability) within a single adaptive direction is compensated by negative feedback in most of the alternative directions. The negative feedback operates as selection not be environmental but by systemic conditions developed by the organization of the organism. The consequences are an imitatively organized system of gene interractions, the rehabilitation of classical systematics, the reality of the "natural system," and, in general, the resolution of the contradiction between neodarwinists and their critics, between reductionists and holists, between "a priori" and "a posteriori" views, between idealism and materialism, and between the notions of freedom and of purpose in evolution.

Biological Evolution↗

PubMed2024

Distinct types of selection and genetic architecture shape molecular variation during the domestication of vegetable crops.

Humans select vegetable crops with desirable traits via a complex evolutionary process called domestication, generating a variety of cultivars worldwide. With advances in sequencing technologies, genomic scans for "signatures of selection" are widely used to identify target loci of selection. In the early phases of domestication, humans tended to favor similar sets of phenotypes in diverse crops, resulting in "domestication syndrome" and parallel evolution in multiple species. Subsequently, adaptation to distinct environments or different consumer preferences has diversified crop cultivars. Here, we review molecular and population genetic studies on genes affecting trait evolution during this complex process. We emphasize that, depending on interactions among different types of selection (directional selection within or divergent selection between groups), the genetic architecture of the target trait (Mendelian or polygenic), and the origin of the causal variant (new mutation or standing variation), the resulting molecular patterns of variation can be highly diverse. Situations in which the typical hard selective sweep model could be applied may be limited. Therefore, it is crucial to obtain a thorough understanding of the target species' historical, environmental, and ecological contexts.

Domestication↗

PubMed1977

Antigen activation of T lymphocytes: influence of major histocompatibility complex.

There is considerable evidence that T-cell activation to soluble antigens occurs only if this is processed by macrophages and displayed appropiately on the cell membrane in association with products of the genes of the MHC. The genes responsible differ according to the cells and antigens involved. For cytotoxicity, targets and killer T cells must share K- or D-region gene products. For delayed-type hypersensitivity to FGG in mice, I-A identity is necessary; for DNFB, identity at either the I, K, or D region is sufficient. Experiments using three different approaches do not support the notion that these genetic constraints are due to the necessity for the T cell and stimulator cell to match an identical gene product or cell-interaction molecule. Rather, they favor the hypothesis that there are receptors on the activated T cell which recognize antigen and products of genes of the MHC. The implications of the results are discussed in terms of (1) different T-cell subsets, (2) the mode of action of Ir genes, and (3) the possible parallel evolution of T-cell receptors for antigen and gene products of the MHC.

Animals↗

PubMed2025

Polyploidy-mediated variations in glutamate receptor proteins linked to Fusarium wilt resistance in upland cotton.

Cotton production in the US faces a serious threat from Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4), a soil-borne fungus causing Fusarium wilt by infecting the roots and vascular system of susceptible cotton, leading to rapid wilting and death. Here, we investigate genetic mechanisms of resistance to FOV4 in the highly resistant upland cotton genotype "U1" using an early-generation segregating biparental population ("U1" × "CSX8308") with comprehensive genomic resources. Reference-grade genomic assemblies of the parents revealed minor structural variations between "U1" haplotypes, a high degree of collinearity at chromosome synteny and micro-synteny levels, and significant divergence from "CSX8308" with 8.9 million SNPs. QTL analysis identified significant markers on chromosomes D03 and A02 linked to reduced Fusarium wilt severity. Within these regions, two glutamate-receptor-like (GLR) genes showed structural variation and overlapped between translocated segments on A02 and D03, suggesting a rare but important reinforcing effect of parallel evolution between susceptible and resistant genotypes. Transcriptome profiles of "U1" under FOV4 infection reveal activation of calcium-binding proteins and transcription factors regulating plant hormones (ethylene, abscisic acid, jasmonic acid, and salicylic acid), along with enzymes involved in cell wall remodeling and phytoalexin production. Advancing cotton improvement depends on incorporating durable genetic disease resistance into high-yielding, high-quality cultivars.

Fusarium↗

PubMed1978

Serum elastase and its inhibitors in the blood of heavily burnt patients.

Serum elastase and its inhibitors were determined in the sera of heavily burnt patients. Serum elastase levels were elevated at two to eight days after a severe burn-accident and returned towards normal values from the 10th day on. Both alpha1-antitrypsin and alpha2-macroglobulin levels were also elevated in the sera of heavily burnt patients. alpha1-Antitrypsin showed a parallel evolution to the elastase level but alpha2-macroglobulin followed a somewhat different time curve. Plasminogen and antithrombin were not elevated significantly. It is suggested that serum elastase may play a role in tissue degradation in burnt patients.

Antithrombin III↗

PubMedDate not supplied

Antigen perception by T lymphocytes. Influence of the major histocompatibility complex.

There is considerable evidence that T cell activation to soluble antigens occurs only if this is processed by macrophages and displayed appropriately on the plasma membrane in association with products of the genes of the major histocompatibility complex. The genes responsible differ according to the antigens involved. For cytotoxicity, targets and killer T cells must share K or D region gene products. For delayed type hypersensitivity to fowl gammaglobulin in mice, I-A identity is necessary; for dinitrofluorobenzene, identity at either the I, K or D region is sufficient. Experiments using three different approaches do not support the notion that these genetic constraints are due to the necessity for the T cell and stimulator cell to match an identical gene product or "cell interaction molecule." Rather they favour the hypothesis that activated T cells recognize antigen and products of genes of the major histocompatibility complex. The implications of the results are discussed in terms of the mode of action of immune responsiveness (Ir) genes and of the possible parallel evolution of T cell receptors for antigen and gene products of the major histocompatibility complex.

Animals↗

PubMedDate not supplied

[Unit activity of rabbit medial septum in early ontogenesis].

In experiments on 7-20 and 75-day-old rabbits, the activity of units of the septal nuclei, the nucleus of the diagonal band of Broca (NBD), nucleus medialis (NSM) and the EEG of dorsal hippocamp (the CA2-CA3 fields) have been recorded. It was shown that the specific discharge pattern of septal neurons (the bursts) appears on 8-11th days under action of eserine. The distinct bimodal pattern of the interval histograms of the septal units appeared from the 14th day. The burst discharge pattern of NBD and NSM neurones reached a definitive level by the 20th day. The parallel evolution of discharge pattern of the septal units and the EEG of the hippocamp is observed in ontogenesis, the formation of hippocampal theta activity correlating with enhancement of the average frequency of the septal (NBD, NSM) neuronal activity, with shortening to the interval between the discharges within the bursts and with enhancement of the regularity of the bursts.

Aging↗

PubMed1975

Palatal epithelium of a monotreme and a marsupial.

The palatal epithelium of a monotreme, Tachyglossus aculeatus and a marsupial, Tarsipes spenserae were examined histologically and with the scanning electron microscope. Each animal possess keratinized palatal spines which although histologically similar, show significant differences in their external morphology. It is suggested that the spines in each case are highly differentiated filiform papillae which have developed as a compensatory mechanism of mastication, since both animals are in effect, edentulous. In the light of these findings and observations on the tongue of both animals, it is suggested that a degree of parallel evolution of the palate (as part of the masticatory apparatus) has occurred.

Animals↗

PubMedDate not supplied

The foetal development of the rabbit lung: a cytologic, cytochemical and histoenzymatic study.

The developmental peculiarities of the rabbit lung were analyzed in foetuses of 14 and 23 days, and in newborns having respired 30 min. and 48 hrs. Cytochemical, histoenzymatic and quantiative cytologic methods were used. The parallel evolution of epithelial and mesenchymal cells was quantified using conventional fields. The development of air spaces was morphometrically appreciated. Acid and neutral mucopolysaccarides, nucleic acids, and enzymic activities (AcPh-ase, AlkPh-ase, ATP-ase, AMP-ase, SDH, MDH, LDG, G1-6-ph-DH, proline-oxydase, hydroxyproline-2-epimerase, unspecific esterase, TwE-ase, beta-gal-ase and beta-gluc-ase, alanyl- and leucineaminopeptidase) were investigated. This complex analysis showed that in a first phase the development mainly involved the epithelial cells, while the proliferation of mesenchymal ones remained constant. In a second phase, the epithelial cell increase became slower, and the mesenchymal cells were decreasing. At the same time the air spaces were continuously increasing. During this process, neutral mucopolysaccharides were synthesized in epithelial cells and in cartilaginous nodules, and sometimes in mesenchymal cells. The RNA was continuously increasing both in epithelial and mesenchymal cells. The high enzymic activities in the 14-day foetuses appeared to be limited to AcPh-ase, AlkPh-ase, and SDH in both epithelial and mesenchymal cells, the LDH in epithelial and the ATP-ase and AMP-ase mainly in mesenchymal cells. At the same time, the G1-6-ph-DH obviously marked the epithelial cell differentiation. In the other foetal and newborn lungs, the enzymic activities appeared to be more various by limitation of AcPh-ase to epithelial elements and of AlkPh-ase to mesenchymal and vascular ones, by activation of proline-oxydase and especially of hydroxyproline-2-epimerase in pleura and peribronchovascularly, by intensification of the unspecific esterase: the other enzymes active in the 14-day foetuses were now weaker. The activity of beta-gal-ase, beta-gluc-ase, and of peptidases was missing during the entire development of the foetal rabbit lung. The corroboration of these data suggested the relation between the differentiation of enzymic activities and the development of foetal rabbit lung, the strong relations between AcPh-ase activity and the epithelial elements, and of AlkPh-ase and ATP-ase with the mesodermo-mesenchymal ones, the marking of epithelial cell differentiation by the G1-6-ph-DH activity, the presence of SDH in the basal corpuscles of differentiating cili, the increase of enzymes making inactive the hydroxyproline in zones in which connective tissue is developing, the low differentiation of hydrolases (related to the absence of air and blood transport of products) and the lack of peptidase activity corresponding to the reduced pulmonary degradation of proteins (as in adult lungs).

Adenosine Monophosphate↗

PubMed1992

Detection of bilateral and symmetrical anomalies in technetium-99m-HMPAO brain SPECT studies.

The detection of bilateral and symmetrical regional cerebral blood flow (rCBF) abnormalities requires knowledge of the antero-posterior rCBF distribution in normal subjects of all age groups. These data are very difficult to obtain in children for ethical reasons and in older subjects because of the necessity of recruiting a large number of healthy volunteers from each age group. Therefore, to obtain normal values of antero-posterior rCBF distribution, we have retrospectively selected a group of patients with a low probability of having cerebral lesions, whose 99mTc-HMPAO brain SPECT studies were analyzed semiquantitatively. Cerebellum/mean cerebral cortex index when compared to young adults was higher in the neonatal period, slightly lower between 2 mo and 15 yr, and more or less identical after 15 yr. Cortico/occipital indexes exhibit considerable changes during the first year of life due to important differences in maturation timing of cerebral cortical areas. After 1 yr, all cerebral cortical areas approximately displayed a parallel evolution. A slight increase in fronto/occipital and temporo/occipital indexes was, however, still observed during childhood, while in elderly subjects there was a trend towards a decrease in all cortico/occipital indexes (particularly in prefrontal and motor areas). Changes that occurred after 1 yr were, however, usually smaller than interindividual variation. Despite the large range of "normal" values, the antero-posterior analysis could be useful in various neurologic disorders, because it allows detection of symmetrical rCBF anomalies undiagnosed by the right-left analysis.

Adolescent↗

PubMed1977

[Correlation between inhibition of stimulatory membrane repolarization and positive inotropic response caused by ouabain in rat heart].

During a stimulus train, the diastolic membrane potential of rat atria exhibits a depolarization phase followed by a slower repolarization phase which has been attributed to the activation of an electrogenic sodium pump (ATPase Na+, K+). This pump seems to be all the more active as stimulation frequency is higher. The parallel evolution of the sodium pump inhibition and a positive inotropic effect in response to ouabain perfusion, suggests that the enzymatic inhibition is directly involved in the development of the cardiotonic effect of digitalis.

Animals↗

PubMed1977

[Vogt-Koyanagi-Harada disease. About two observations (author's transl)].

After a reminder of clinical symptoms and development of the V.-K.-H. disease, some histological and clinical observations are related. The clinical observations are very characteristic of the V.-K.-H. disease. There are only two notable points: in both observations, a very low lymphocytic reaction to phytohemaglutinin and in the first observation, the presence of an anemia with parallel evolution to the uveitis. The histological examination of the depigmented area shows an infiltrate as described by Perrot, around the involved area in vitiligo. Ultrastructural study identifies 250 angströms wide particles that appear to be particles of alpha-glycogene, well developed amyelinic endings, and lastly, lymphocytoid cells closely joined with dendritic cells having internal granulations. These aspects have already been found in the iris by the Japanese authors, and they evoked an immunological mechanism.

Adult↗