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PubMed2003

Electrophile and oxidant damage of mitochondrial DNA leading to rapid evolution of homoplasmic mutations.

mtDNA mutations occur in a wide variety of degenerative diseases and cancer. mtDNA seems to be more susceptible to DNA damage and consequently sustains higher rates of mutation than does nuclear DNA (nDNA). Many of the somatic mtDNA mutations in human cancers are located in the displacement loop (D-loop) and in particular in a polycytidine stretch (C-tract) termed D310. The D310 region exhibits polymorphic length variation among individuals and has been described as a "hot spot" for somatic mutations in many cancer types. We used real-time quantitative PCR to analyze mtDNA integrity, damage repair, and induced mutations after exposure of human adult retinal pigment epithelial (ARPE)-19 cells to 4-nitroquinoline 1-oxide, a UV-mimetic and adduct-forming carcinogen, and tert-butyl hydroperoxide, an oxidant. The mtDNA-damage profile depended on the region. Thus, the tRNA coding for glycine (tRNA(G)) was the least affected region, whereas the D-loop, and especially its D310 region, were most sensitive to damage. The time course of repair of mutations of the D-loop and especially the D310 region after exposure to DNA-damaging agents was delayed when compared with other regions and gave rise to common D310 C-tract frame-shift mutations. The induced mutations in the D310 region were predominantly homoplasmic only 7 days after exposure to damage. Our results establish that the D-loop (especially its D310 region) is highly susceptible to mutations because of its vulnerability to DNA damage and inefficient repair mechanisms. Our findings may explain the high frequency of homoplasmic D310 somatic mutations in many tumor types.

Base Sequence↗
PubMedDate not supplied

Synteny of SIS and IGLC in owl monkeys. Evidence for karyotype evolution.

Two cloned human DNA sequences specific for the SIS and IGLC genes were hybridized with DNAs from panels of rodent-owl monkey somatic cell hybrids. Independent segregation analysis of the related owl monkey DNA sequences for these two genes demonstrated that both the SIS locus and the IGLC locus are localized on owl monkey chromosome 3 of karyotype VI, chromosome 3 of karyotype V, and chromosome 6 of karyotype IV. These syntenic assignments provide genetic evidence for the homology of, at least, a portion of these chromosomes from three owl monkey karyotypes. The findings also help to redetermine the possible chromosome rearrangement that characterized the chromosome complement of owl monkey from Panama and northwestern Colombia with karyotypes II, III, IV, VIII, and IX from other owl monkey populations with karyotypes I, V, VI, VII, X, and XI.

Animals↗
PubMed2000

Mate selection and the evolution of highly polymorphic self/nonself recognition genes.

Multicellular organisms use the products of highly polymorphic genes to distinguish self from conspecific nonself cells or tissues. These allorecognition polymorphisms may regulate somatic interactions between hosts and pathogens or between competitors (to avoid various forms of parasitism), as well as reproductive interactions between mates or between gametes (to avoid inbreeding). In both cases, rare alleles may be advantageous, but it remains unclear which mechanism maintains the genetic polymorphism for specificity in self/nonself recognition. Contrary to earlier reports, we show that mate selection cannot be a strong force maintaining allorecognition polymorphism in two colonial marine invertebrates. Instead, the regulation of intraspecific competitive interactions appears to promote the evolution of polymorphisms in these species.

Alleles↗
PubMed2002

Functional substitution for TAF(II)250 by a retroposed homolog that is expressed in human spermatogenesis.

TAF(II)250, the largest subunit of the general transcription factor TFIID, is expressed from the human X chromosome, at least in somatic cells. In male meiosis, however, the sex chromosomes are transcriptionally silenced, while the autosomes remain active. How then are protein-encoding genes transcribed during human male meiosis? Here we present a novel autosomal human gene, TAF1L, which is homologous to TAF(II)250 and is expressed specifically in the testis, apparently in germ cells. We hypothesize that during male meiosis, transcription of protein-encoding genes relies upon TAF1L as a functional substitute for TAF(II)250. Like TAF(II)250, the human TAF1L protein can bind directly to TATA-binding protein, an essential component of TFIID. Most importantly, transfection with human TAF1L rescued the temperature-sensitive lethality of a hamster cell line mutant in TAF(II)250. TAF1L lacks introns and evidently arose by retroposition of a processed TAF(II)250 mRNA during primate evolution. The observation that TAF1L can functionally replace TAF(II)250 provides experimental support for the hypothesis that during male meiosis, autosomes provide cellular functions usually supplied by the X chromosome in somatic cells.

Evolution, Molecular↗
PubMed1992

Molecular cloning and chromosomal mapping of the human gene for the testis-specific catalytic subunit of calmodulin-dependent protein phosphatase (calcineurin A).

A cDNA for an alternatively spliced variant of the testis-specific catalytic subunit of calmodulin dependent protein phosphatase (CaM-PrP) was cloned from a human testis library. The nucleotide sequence of 2134 base pairs (bp) encodes a protein of 502 amino acids (Mr approximately 57,132) and pI 7.0. The cDNA sequence differs from the murine form of this gene by a 30 bp deletion in the coding region, the position of which matches those in the two other genes for the catalytic subunit. These data indicate that this alternative splicing event arose prior to the divergence of the three genes. The deduced sequence of the human protein is only 88% identical to the homologous murine form, in striking contrast to the other two CaM-PrP catalytic subunits which are highly conserved between mouse and human (approximately 99%); this indicates a more rapid rate of evolution for the testis-specific gene. Analysis of Southern blots containing DNA from human-hamster somatic cell hybrids show that the gene is on human chromosome 8.

Alternative Splicing↗
PubMed1997

Somatic gene transfer approaches to manipulate neural networks.

Gene transfer methods can be exploited to create somatic mosaic tissues to elucidate gene product action in cells comprising a network. This article describes the evolution of approaches beginning from herpes amplicon vectors with constitutive gene expression to herpes vectors with regulated gene expression and concludes with the development of a combined germline/somatic gene transfer method that allows for highly versatile spatial and temporal control of in vivo gene expression. Where possible examples of each approach are provided. In addition, the advantages and limitations of the approaches are discussed.

Animals↗
PubMed1977

Effects of ethephon, ethylene, and 2,4-dichlorophenoxyacetic Acid on asexual embryogenesis in vitro.

Asexual embryogenesis in Daucus carota L. ;Queen Anne's Lace' callus was suppressed by Ethephon, ethylene, and 2,4-dichlorophenoxyacetic acid (2,4-D). The Ethephon effect could be attributed to volatile and nonvolatile substances. The volatile component was probably entirely ethylene. Ethylene was liberated in the cultures in direct proportion to Ethephon added to the medium. Autoclaving of Ethephon caused a substantial decrease of measurable ethylene. Continuous exposure of callus to 5 mul/l ethylene depressed somatic cell embryogenesis, but not markedly. Depression of embryogenesis by 2,4-D was unrelated to ethylene evolution.

Journal Article↗
PubMed1984

Species-specific rDNA transcription is due to promoter-specific binding factors.

RNA polymerase I transcription factors were purified from HeLa and mouse L cell extracts by phosphocellulose chromatography. Three fractions from each species were found to be required for transcription. One of these fractions, virtually devoid of RNA polymerase I activity, was found to form a stable preinitiation complex with small DNA fragments containing promoter sequences from the homologous but not the heterologous species. These species-specific DNA-binding factors can explain nucleolar dominance in vivo in mouse-human hybrid somatic cells and species specificity in cell-free, RNA polymerase I-dependent transcription systems. The evolution of species-specific transcriptional control signals may be the natural outcome of a special relationship that exists between the RNA polymerase I transcription machinery and the multigene family coding for rRNA.

Animals↗
PubMed1983

The concept of Schizophrenia. Kraepelin-Bleuler-Schneider.

The concept of schizophrenia has changed since it was first introduced by Kraepelin. To overlook or misunderstand this evolution will lead to confusion with adverse effects on the clinic and on research. Kraepelin's exclusively somatic approach to the study of the illness gave rise to a variety of attempts to provide a wider theoretical framework which will accommodate a subjective psychological approach. The first of these attempts was that by Bleuler and Jung, but it brought with it new difficulties. Jasper's methodology was applied to the study of schizophrenia by Schneider, and it creates the theoretical space which will accommodate both the objective and subjective study of the illness and its victim as a person. An attempt is made here to outline a brief history of these ideas.

Germany↗
PubMed2003

[Emergency management of acute pain in oncology].

Acute pains requiring emergency management in oncology can be considered as physiopathological, somatic or visceral nociceptive pains. They are linked: to the tumour, indicating a modification of the tumoural evolution (necrosis, haemorrhage, fracture, acute obstruction of hollow organs or canals, occlusion, hydronephrosis); to the treatment: (inflammation of mucosal membranes, anusitis, post PL syndromes); and to invasive investigations. They are equally neuropathic, revealing an underlying threatened or confirmed medullary compression, or induced by neurotoxic chemotherapy. They are also analysed according to their mode of apparition: mechanical, arising as acute on chronic pain (the pre-fracture pain of metastases); insufficiency of the duration of therapeutic efficacity; an acute episode of neuropathic pain that is often lancing, unpredictable and inevitable. In all cases, it needs to be quantitatively and qualitatively analysed: evaluation, flavour of the symptoms; in order to choose one or a combination of adapted molecules, true antalgics or co-antalgics, antidepressants and anticonvulsants. To counteract this pain, medications with a short onset of action and a short half-life should be used to avoid side effects. These are administered in an intercurrent manner, initially starting at a low dose, modified daily according to the utilisation of supplementary doses. It is necessary to anticipate pain provoked by physical examinations or nursing care as much in the timing as the pharmacology, in using antalgics and/or anxiolytics with a short duration of action. Acutely emerging pains, whatever be their type, arising in the context of cancer and long-term pain are sensitising elements to all further pains, as they imprint in the memory, and are very negatively conditioned by the anguishing context of the illness.

Acute Disease↗
PubMedDate not supplied

The self-nonself discrimination and the nature and acquisition of the antibody repertoire.

Network ideas are confronted with current hypotheses for the origin of antibody diversity and self-nonself discrimination. The difficulties of reconciling the promethean evolution of the antibody system with "germ line" theories are discussed, as well as the problems of "somatic" hypotheses to explain the completeness of the antibody repertoire. The formal incompatibility of the network theory with ideas basing self-nonself discrimination on the elimination of self-reactive cells is demonstrated, as well as the difficulties of these and other environment-dependent hypotheses for lymphocyte activation, to encompass the internal activity in the immune system. It is argued, on the other hand, that the limitations of the network theory in providing a functional basis for the idiotypic network and in accounting for self-nonself discrimination, can be solved by finding in a complete repertoire of antibody-combining sites the complementary structures to growth receptors on B lymphocytes, and by using these as internal mitogens in the expansion of the precursor cell pools and in the maintenance of the mature steady states. Letting self-nonself discrimination be accounted for by such growth receptors, both the integrity of the antibody repertoire and the internal activity in the system can also be ensured. Moreover, by postulating a germ line origin for the antireceptor antibodies and by accepting idiotypic cross-reactivity between growth receptors and other germ line antibodies, the possibilities are set for a phylogenetically and ontogenically autonomous immune system embodied with the capabilities for self-expansion, diversification and selection of available repertoires. Its promethean characteristics are explained by its completeness, and this is achieved by idiotypic interactions between growth receptors and a limited number of complementary or cross-reactive germ line antibodies, naturally selected on the basis of their structural relationships with growth receptors.

Animals↗
PubMedDate not supplied

[Evaluating quality of life of depressed patients in ambulatory care treatment].

This study concerns 1257 depressed outpatients, whose quality of life was evaluated before the beginning of a fluvoxamin treatment and six weeks later. We used the "Subjective Quality of Life Profile", questionnaire which has been previously validated in somatic diseases. The validation performed with these depressed patients appears to be quite satisfactory. The results provide a good description of the patients before the treatment: they seem to be indifferent to most domains by their health which they describe as very unsatisfactory. Contrasting with these results, patients' expectations appear to be very important in most domains, and the greater these initial expectations the poorer the evolution of their quality of life. After six weeks the patients' improvement in their quality of life is quite obvious especially in the somatic area. Another interesting finding concerns the high initial level of patients' expectations as compared with patients having somatic diseases. The higher these expectations, the poorer the outcome. It thus appears that a very sensitive self-questionnaire dealing with patients' quality of life in depression is available.

Adult↗
PubMedDate not supplied

Contributions to the evolutionary study of the liver afferent veins.

The extra- and intrahepatic venous afferent devices have been followed up in their evolution in all the classes of vertebrates and in man. There were studied 319 cases in 19 vertebrate species, in situ by the method of corrosion preparates with acid-resistant plastic materials or radiographies. The extraparenchymal afferent venous device shows an evolution characterized by the maintenance and improvement of the visceral hepatic venous system and by the gradual freeing of somatic parietal afferences, substantiating new anatomical notions like "liver visceralization", "hepatic parietal territories" and allowed the ascertainment of an evolutionary phyletic line of the liver based on the progressive diminution of the hepatic parietal territory. The basic characteristic type of intrahepatic distribution of the portal vein was sketched beginning with the testudine reptiles and was maintained including man. The liver segmentary angioarchitecture appeared already in birds. These findings allowed the homologation of the cleaved liver with the unitary liver of mammals and man as well as the homologation of the hepatic organ of mammals, birds and of some reptiles, and the understanding of the emergence variation of the portal vein ventrocranialis dexter.

Animals↗
PubMed2000

Analysis of expressed immunoglobulin heavy chain genes in familial B-CLL.

In this study, we wished to determine whether familial chronic lymphocytic leukemia of B-cell phenotype (CLL) shares with sporadic B-CLL the same immunoglobulin (Ig) heavy chain variable region (VH) gene usage and occurrence of somatic mutation, to gain insight into the pathogenetic relatedness of these epidemiologically distinct forms of CLL. We therefore analyzed the expressed Ig heavy chain genes in 23 cases (11 families) of familial CLL, and compared these results with data previously reported for sporadic CLL. In addition, we assessed the relationship of the occurrence of somatic mutation to several clinical and phenotypic features. The distribution of V genes among these cases was similar to that observed in sporadic CLL: VH3 > VH1 > VH4. Thirteen of the 23 cases (57%) showed germ line VH gene sequences, whereas somatic mutations were detected in 10 cases (43%). The average mutation frequency of these latter 10 cases of was 6.7% (ranging from 1.7% to 8.8%), and evidence of antigen selection was noted in 6. Intraclonal variation, followed by clonal evolution and the appearance of a second clone over a 20-year period was observed in 1 case, suggesting that mutations can continue to accumulate after neoplastic transformation. The presence of somatic mutations correlated with age at presentation, low white blood cell (WBC) count, and low fluorescence intensity of surface CD5, and the potential significance of these relationships is discussed. Our data indicate that familial and sporadic B-CLL display a similar pattern of immunoglobulin gene usage and frequency of somatic mutation, and are consistent with a common ontogeny and immunogenetic origin for these 2 epidemiologically distinct forms of CLL. (Blood. 2000;95:1413-1419)

Adult↗
PubMed1987

Assignment of human tryptophan hydroxylase locus to chromosome 11: gene duplication and translocation in evolution of aromatic amino acid hydroxylases.

A cDNA clone for rabbit tryptophan hydroxylase was used as a probe to identify human tryptophan hydroxylase gene fragments in a panel of hamster-human somatic cell hybrids and determine its chromosomal location in man. A single locus was identified for tryptophan hydroxylase on chromosome 11. Tryptophan hydroxylase is a member of the superfamily of pterin-dependent aromatic amino acid hydroxylases which includes tyrosine hydroxylase, located at 11p15.5-p15, and phenylalanine hydroxylase, located at 12q22-q24.1 in human. The locations of these genes and the evolutionary distance between their sequences suggest that at least three distinct genetic events have occurred during the evolution of the aromatic amino acid hydroxylase superfamily: two sequential gene duplications giving rise to the three distinct hydroxylase loci, and a translocation which separated the tryptophan and tyrosine hydroxylase loci on chromosome 11 from the phenylalanine hydroxylase locus on chromosome 12.

Animals↗