Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “somatic evolution”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 595 records · Page 33Linked to original sources
PubMed2000

[Evolutionary regularities of somatic polyploidy manifestation in salivary glands of gastropod molluscs. I. Subclasses Cyclobranchia and Scutibranchia].

By means of histological and cytochemical methods, including DNA cytophotometry, the salivary glands of 11 species of molluscs of two old gastropod subclasses--Cyclobranchia and Scutibranchia (limpets)--have been investigated. In spite of some anatomical differences, the glandular epithelium of investigated molluscs includes functionally similar cell types: granular cells (with glycoproteid granular inclusions), mucocytes-I (that include sulfatic acid mucopolysaccharides), mucocytes-II (that include neutral and acid polysaccharides and proteins) and also the epithelial ciliated cells. Data of experiments on starvation and synchronous feeding of molluscs testify that all described cell types are independent. According to DNA cytophotometry data, the glandular cell nuclei are diploid in the main; only small part of the nuclei, varying in different species from 0.5 to 5.0%, displayed tetraploid DNA mass. A conclusion is made that in the oldest subclasses of gastropods (Cyclobranchia and Scutibranchia) somatic polyploidy, as a factor of tissue growth in salivary glands, is actually absent.

Animals↗
PubMedDate not supplied

[Psychological aspects of ulcerative rectocolitis (author's transl)].

Ulcerative rectocolitis has been known for quite some time as a psychosomatic disease, it is an organic disease occurring in people with a particular personality rendering them susceptible to certain conflicts or stress which would be able to play a causing role in the appearance or exacerbations of the disease. Insofar as the psychological study is concerned, there are two important points to keep in mind: the role of psychological trauma as a stimulating factor and the basic personality. In 90% of the cases observed, psychological factors are found as provoking the hemorrage, as found by Groen and confirmed by the author. The basic personality is generally the obsessional type with a hypersensibility to rejection and hostility, sometimes of a paranoid dimension. The aggressivity is almost always repressed. The doctor-patient relationship indicates an important dependency as well as a passivity on the part of the patient. Furthermore, these patients rarely express their feelings, even if their behavior is indicative of experiencing intense emotion. By further experimentation, it has been established that these patients have a greater neuro-vegetative fragility than controls, thus demonstrating a greater vulnerability to stress. A pathological relationship between mother and child has almost always been proven. Finally, the principal causal psychological factor in this disease seems to be a relational conflict unresolved between specific figures. The role of psychotherapy influences greatly the disease evolution. the author recounts an interesting research of 900 ulcerative colitis patients, undertaken by O'Connor. In order to insure favorable therapeutic results in ulcerative rectocolitis, one must carefully coordinate a psychological and somatic treatment.

Colectomy↗
PubMed2005

[Bipolar disorders in the elderly].

Usual diagnostic criteria are not suited with the diagnosis of bipolar disorders in the elderly, which then remain often undetected. Bipolar disorders in the elderly are clinically heterogeneous and present with various courses: switch from recurrent depression to mania, early onset or late bipolar disorders. In the elderly, bipolar disorders can take uncommon aspects such as depressive or mixed symptoms, psychosis, mental confusion or dementia. Results from the literature devoted to the evolution of bipolar disorders during life or in terms of age at onset are often contradictory. The prognosis of bipolar disorders in the elderly is poor due to higher prevalence of recurrences, associated somatic disorders, reduced survival and severe handicap. There is an immediate need for collaboration between patients, families, clinicians, researchers, governmental agencies, and third-party payers to improve the diagnosis, treatment, and delivery of services for elderly subjects with bipolar disorders.

Aged↗
PubMedDate not supplied

[Epidemiology of somatoform disorders in the general French population].

A telephone survey based on 504 interviews, representative of the French population over 18, allowed to gauge the annual prevalence and identify the characteristics of somatoform disorders. This study was based on the inventory of 19 symptoms divided into 5 categories: gastrointestinal, pain, dermatological, cardiorespiratory and gynaecologic/urinary. "Medical somatoform disorders" (MSD) were defined as the repeated occurring, during the previous year, of not less than 1 symptom with an evolution duration equal or superior to 6 months, and causing personal and familial or professional problems. Such disorders had, in addition, to motivate one or more medical consultations concluding to the lack of somatic disease. These criteria included those proposed in DSM IV for the diagnosis of "Undifferentiated Somatoform Disorder", except for the exclusion criteria (E) which was not included in this study. Three out of four subjects (76% of the population) declared to endure not less than 1 somatic symptom in the course of the previous year. Near 1 out of 5 subjects (19%) had one MSD. MSD were more frequent among females than among males (sex-ratio F/M = 1.82). This data traces 3 types of phenomena: the somatic disorders prevalence and the consultation ratio in case of somatic disorders were higher among females than males; conversely, MSD ratio among somatic disorders consultants is higher among males than females. MSD prevalence does not vary with age, except for an underrepresentation among patients aged over 65 (13%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2002

Cyclic variation in seasonal recruitment and the evolution of the seasonal decline in Ural owl clutch size.

Plastic life-history traits can be viewed as adaptive responses to environmental conditions, described by a reaction norm. In birds, the decline in clutch size with advancing laying date has been viewed as a reaction norm in response to the parent's own (somatic or local environmental) condition and the seasonal decline in its offspring's reproductive value. Theory predicts that differences in the seasonal recruitment are mirrored in the seasonal decrease in clutch size. We tested this prediction in the Ural owl. The owl's main prey, voles, show a cycle of low, increase and peak phases. Recruitment probability had a humped distribution in both increase and peak phases. Average recruitment probability was two to three times higher in the increase phase and declined faster in the latter part of the season when compared with the peak phase. Clutch size decreased twice as steep in the peak (0.1 eggs day-1) as in the increase phase (0.05 eggs day-1). This result appears to refute theoretical predictions of seasonal clutch size declines. However, a re-examination of current theory shows that the predictions of modelling are less robust to details of seasonal condition accumulation in birds than originally thought. The observed pattern can be predicted, assuming specifically shaped seasonal increases in condition across individuals.

Adaptation, Physiological↗
PubMed2002

Initiation of human astrocytoma by clonal evolution of cells with progressive loss of p53 functions in a patient with a 283H TP53 germ-line mutation: evidence for a precursor lesion.

Little is known about the genetic and molecular events leading to the early stages of human astrocytoma formation. To examine this issue, we analyzed the significance of sequential accumulation of two somatic point mutations (R267W and E258D) in the TP53 gene during the initiation of astrocytoma in a patient born with a single germ-line p53 point mutation (R283H). We adapted a p53 transcriptional assay in yeast to establish the temporal occurrence and allelic distribution of the p53 mutations present in the patient and characterized these mutations through functional assays and structural modeling. Our results show that the first somatic mutation occurred at codon 267 on the p53 allele harboring the germ-line mutation R283H, whereas the second somatic mutation occurred in the remaining wild-type (wt) allele at codon 258. These two mutations induced the formation of tumor cells with the genotype p53(267W+283H/258D), which comprised 70% of the cells in the primary WHO grade II astrocytoma. Another 8% of cells within the tumor had the partially mutated genotype p53(267W+283H/WT) and represented the remnants of a clinically undetectable intermediate stage of astrocytic neoplastic transformation. The remaining 22% of cells had the constitutive p53(283H/WT) genotype and likely consisted of nontumor cells. Functional analysis of the p53 alleles present in the patient's tumor indicated that the germ-line p53(R283H) could transactivate the CDKN1A((p21, WAF1, cip1, SDI1)) but not the BAX gene and retained the ability to induce growth arrest of human glioblastoma cells. The p53(R267W+R283H) and p53(E258D) were incapable of transactivating either promoter or inducing growth arrest. Modeling of p53 interaction with DNA suggests that R283H mutation may weaken the sequence-specific interaction of p53 lysine 120 with the BAX gene but not the CDKN1A p53-responsive elements. Taken together, these results have characterized, for the first time, the genetic events defining a clinically undetectable precursor lesion leading to a grade II astrocytoma. They also suggest that astrocytoma initiation in this patient resulted from monoclonal evolution driven by a sequential loss of proapoptotic and growth arrest functions of p53.

Adult↗
PubMed2003

Ribosomal DNA variation, recombination and inheritance in the basidiomycete Trichaptum abietinum: implications for reticulate evolution.

Two divergent nuclear ribosomal DNA (nrDNA) types, designated alpha and beta, were found distributed in 11 North European populations of the basidiomycete Trichaptum abietinum. These types differed by a 220 bp indel in the internal transcribed spacer 1 (ITS1) sequence and a number of linked substitutions and small indel motives in the internal transcribed and intergenic spacers (ITS1, ITS2, IGS1 and IGS2). The alpha and beta haplotypes co-occurred in heterozygous somatic individuals (dikaryons) and segregated in a Mendelian fashion in monokaryotic single spore progenies. This result suggests that the haplotypes are encoded in different nuclei of field-collected dikaryons and inherited as a single locus. No meiotic recombinants were observed among the sequenced monokaryons. Population genetic analyses by PCR-RFLP revealed that a low frequency of evolutionary intermediate nrDNA types also existed in natural populations, presumably as a result of meiotic recombination of alpha and beta nrDNA. The existence of divergent nrDNA types in T. abietinum could be a result of a former independent evolution followed by a hybridization event. Phylogenetic analyses of ITS sequences suggest that the sister taxon T. fusco-violaceum has been involved in the evolutionary history of T. abietinum. Sequence polymorphisms observed in the translation elongation factor 1alpha (efa) and glyceraldehyde-3-phosphate dehydrogenase (gpd) genes, did not reveal two well-defined types of these genes. The results are discussed in the light of other evolutionary mechanisms as well.

DNA, Fungal↗
PubMed1996

Heterochrony and neotenic salamanders: possible clues for understanding the animal development and evolution.

A synthesis of developmental genetics with evolutionary genetics is now making possible to understand significant evolutionary changes in multicellular organisms. The key concept for unifying the two must be heterochrony. Heterochrony causes evolutionary modifications due to changes in timing and/or rate of development. The heterochrony is conventionally categorized into three patterns as neoteny (retardation in somatic development), progenesis (acceleration in gonadal development), and direct development (acceleration in somatic development, resulting in lack of larval or tadpole stages). A lot of species showing neoteny are known in urodeles, but not in anurans. Neotenic urodeles are also divided into three categories; permanent or obligate, "inducible" obligate and facultative neotenies. Hynobius retardatus, a specific population of which had been reported to show neoteny but is believed to be extinct at present, has become to be used for experimental analysis of heterochronic expression of several adult characters during its ontogeny. Gonadal maturation and a transition of globin subunits from larval to adult types have been shown to occur independently on the morphological metamorphosis in H. retardatus. Mechanisms underlying the heterochrony, including morphogenetic clock, heterochronic genes in Drosophila and C. elegans, temporal colinearity in Hox gene complex in mice, and atavistic transformation induced by altered expression of Hox genes are discussed in terms of current molecular biology.

Animals↗
PubMed2004

The biopsychosocial model in medical research: the evolution of the health concept over the last two decades.

The object of this study was to assess the change towards a biopsychosocial health concept among medical researchers in the last two decades, after the explicit criticism of the biomedical model in the late 1970s because of its somatic reductionism. The concepts of 'health' or 'healthy status of an individual' as reported as variable in empirical articles published in the journal The Lancet over the years 1978-1982 (period a) and 1996-2000 (period b) were searched by means of Medline and compared for their definition of these variables. None of the 52 examined papers set out a positive and replicable definition of 'health' (seven papers) or 'healthy status' (45). No difference was found between the two periods studied except for the failure of reports to describe 'healthy status' at all (65.5% in a, 19% in b). Most articles do it in an indirect way, namely through exclusion conditions of subjects taking part in treatment or control groups. Only three studies include psychological dimensions in their measures of 'healthy status' (two in a, one in b). Concerning 'health', all seven examined papers include psychological or both psychological and social dimensions. Although a change towards a more holistic concept of health has occurred in academic and institutional contexts over the last few decades, there does not appear to have been a parallel change in the practical domains of medicine. Possible reasons are discussed, specially the difficulty of applying the biopsychosocial model in medical care and the difficulty of competing with the traditional biomedical concept of health, which has proved fruitful and dominant in medicine over the past three centuries.

Attitude of Health Personnel↗
PubMed1997

Cell cycle checkpoints, chromosome stability and the progression of cancer.

During the evolution of normal cells into cancer cells, the occurrence of multiple mutations results in genetic instability. Mutations in DNA repair genes such as those of mismatch and excision repair predispose the carriers of these mutations to cancer by increasing the level of genomic instability. A variety of chromosome aberrations, such as abnormal ploidy, whole chromosome loss or chromosome amplification are commonly observed in cancer cells. From one cell division to the next, mammalian cells pass through an organized series of controlled events referred to as the cell cycle. In order to pursue an ordered series of molecular events, the initiation of an event during cell cycle progression is dependent on the successful completion of an earlier event. The cell cycle is divided into two major phases, namely, M(mitotic) phase and interphase. Interphase can be further divided into three distinct phases termed G1 (gap 1), S(DNA synthesis) and G2(gap2) phases (Fig. 1). Along with the machinery that promotes cell cycle progression, cells are also equipped with cell cycle checkpoints that ensure correct ordering of events in the cell cycle. The idea of "the cell cycle checkpoint" was first introduced by Hartwell and Weinert (1989) as "the arrest of a cell at a particular phase of the cycle due to a lack of appropriate signals for cell cycle progression". Until the checkpoint machinery receives the appropriate signal, the cell will not be allowed to make transition from one phase of the cell cycle to the next. Thus, the major role of checkpoint control is to minimize somatic genetic alterations and/or events affecting cellular survival. When one or more components of a cell cycle checkpoint are mutated, the chances of genetic instability during one round of the cell cycle increase accordingly with consequent acceleration of cellular evolution from the normal to the cancerous state. Therefore, mutations in checkpoint controls may predispose cells to cancer by causing genomic instability. In this review, I will focus on the potential roles of cell cycle checkpoints in the progression of malignancy.

Cell Cycle↗
PubMed1999

Junctional amino acids determine the maturation pathway of an antibody.

We found that two distinct antibody maturation pathways exist in the immune response of C57BL/6 mice to (4-hydroxy-3-nitrophenyl)acetyl and that the junctional amino acid introduced by a process far preceding somatic hypermutation determined the pathway of affinity maturation. Antibodies belonging to each pathway clearly separated into two separate branches of a phylogenic tree. We also constructed a three-dimensional fitness landscape for antibody evolution by introducing the association constants of the antibodies into the phylogenic tree as the third axis, allowing us to comprehend the significance of junctional diversity in the "evolvability" of antibodies. Thermodynamic analyses of the antigen-antibody interactions suggested that a high conformational versatility in the antigen-combining site allows for the enhanced evolvability of antibodies.

Amino Acid Sequence↗
PubMed2005

EMBRYONIC FACTOR 1 encodes an AMP deaminase and is essential for the zygote to embryo transition in Arabidopsis.

Fusion of the egg and the sperm cells in plants produces a zygote that develops into an embryo. Screening of ethyl methanesulfonate-mutagenized populations of Arabidopsis led to the identification of EMBRYONIC FACTOR 1 (FAC1), a locus that gives a zygote-lethal phenotype when mutated. The FAC1 gene was identified by positional cloning and confirmed by a genetic complementation test against a T-DNA insertion allele. It encodes an AMP deaminase (AMPD) that is known in human and yeast to convert AMP to IMP to maintain the energy potential. Expression of FAC1 in a yeast AMPD mutant after removal of its N-terminal putative transmembrane domain complemented the mutant phenotype, suggesting a functional conservancy but a structural divergence through evolution. Although a low level of FAC1 expression was observed in all organs tested, using a reporter construct we observed a significantly increased FAC1 expression in the zygote, early embryo and endosperm. Furthermore, during somatic embryogenesis, a high level of FAC1 expression was observed in developing embryos including putative embryogenic cells. FAC1, therefore, represents one of the earliest expressed genes known in plants. It may act through AMP depletion to provide sufficient energy for the zygote to proceed through development.

AMP Deaminase↗
PubMed1993

Mechanisms of multistep carcinogenesis and carcinogen risk assessment.

Many different types of chemical exposures can increase the incidence of tumors in animals and humans, but usually a long period of time is required before the carcinogenic risk of an exposure is manifested. Both of these observations can be explained by a multistep/multigene model of carcinogenesis. In this model, a normal cell evolves into a cancer cell as the result of heritable changes in multiple, independent genes. The two-stage model of initiation and promotion for chemical carcinogenesis has provided a paradigm by which chemicals can act by qualitatively different mechanisms, but the process of carcinogenesis is now recognized as more complex than simply initiation and promotion. Even a three-stage model of initiation, promotion, and progression, which can be operationally defined, is not adequate to describe the carcinogenic process. The number of genes altered in a cancer cell compared to a normal cell is not known; recent evidence suggests that 3-10 genetic events are involved in common adult malignancies in humans. Two distinct classes of genes, protooncogenes and tumor-suppressor genes, are involved in the cancer process. Multiple oncogenes may be activated in a tumor, while multiple tumor-suppressor genes may be inactivated. Identification of the genes involved in carcinogenesis and elucidation of the mechanisms of their activation or inactivation allows a better understanding of how chemical carcinogens influence the process of neoplastic evolution. The findings of multiple genetic changes (including point mutations, chromosomal translocations, deletions, gene amplification, and numerical chromosome changes) in activated protooncogenes and inactivated tumor-suppressor genes provide experimental support for Boveri's somatic mutation theory of carcinogenesis. In addition to mutagenic mechanisms, chemicals may heritably alter cells by epigenetic mechanisms and enhance the clonal expansion of altered cells. Most chemical carcinogens operate via a combination of mechanisms, and even their primary mechanism of action may vary depending on the target tissues. The classification of chemicals by mechanism of action or by nongenotoxic or genotoxic activity has certain inherent difficulties because no classification of chemicals is exhaustive or definitive.

Animals↗
PubMed1984

[The schizophrenic patient and his body: remarks on the psychosomatic economy of dissociative psychoses].

For schizophrenic patients, memory and desire are not bodily experiences. Mnemonic traces can be mobilized only at the cost of acute psychotic disintegration of the Self. This paper emphasizes the importance of understanding the Ego structure, the narcissistic economy and psychotic defenses (denial, splitting) as a psychosomatic the organization. Indeed, during somatic illness we observe a reintegration of the body as the hinge between emotional and symbolic aspects of subjective experience. The author suggests that the psychosomatic viewpoint is particularly useful in understanding the clinical evolution of schizophrenia, in psychotherapeutic management of transference and in the elaboration of psychiatric care policies for such patients.

Body Image↗
PubMed2002

Physical localization of the 18S-5.8S-26S rDNA and sequence analysis of ITS regions in Thinopyrum ponticum (Poaceae: Triticeae): implications for concerted evolution.

Fluorescence in situ hybridization was used in Thinopyrum ponticum, a decaploid species, and its related diploid species, to investigate the distribution of the 18S-5.8S-26S rDNA. The distribution of rDNA was similar in all three diploid species (Th. bessarabicum, Th. elongatum and Pseudoroegneria stipifolia). Two pairs of loci were observed in each somatic cell at metaphase and interphase. One pair was located near the terminal end and the other in the interstitial regions of the short arms of one pair of chromosomes. However, all of the major loci in Th. ponticum were located on the terminal end of the short arms of chromosomes, and one chromosome had only one major locus. The maximum number of major loci detected on metaphase spreads was 20, which was the sum of that of its progenitors. The interstitial loci that exist in the possible diploid genome donor species were probably 'lost' during the evolutionary process of the decaploid species. A number of minor loci were also detected on whole regions of two pairs of homologous chromosomes. These results suggested that the position of rDNA loci in the Triticeae might be changeable rather than fixed. Positional changes of 18S-5.8S-26S rDNA loci between Th. ponticum and its candidate genome donors indicate that it is almost impossible to find a genome in the polyploid species that is completely identical to that of its diploid donors. The possible evolutionary significance of the distribution of the rDNA is also discussed. Internal transcribed spacer (ITS) regions of nuclear DNA in Th. ponticum were investigated by PCR amplification and sequencing. The sequence data from five positive clones selected at random, together with restriction site analysis, indicated that the ITS repeated units are nearly homogeneous in this autoallodecapolypoid species. Combined with in situ hybridization results, the data led to the conclusion that the ITS region has experienced interlocus as well as intralocus concerted evolution. Phylogenetic analyses showed that the sequences from Th. ponticum have concerted to the E genome repeat type.

DNA, Ribosomal Spacer↗
PubMed1976

Relative DNA contents of somatic nuclei of ox, sheep and goat.

Diploid ox nuclei contain about 14% more DNA than nuclei from sheep of the same sex. Goat nuclei have a similar DNA content to those of sheep. In view of the similar chromosome banding patterns in these species, it appears that chromosome evolution must have involved numerous minute interstitial deletions of additions of DNA. Although chromosomes which have similar banding patterns in these three species may be regarded as homologous in this respect, and can be regarded as having a common evolutionary origin, they are not homologous for the quantity of their DNA.

Animals↗
PubMed2001

Spatial and temporal control of RNA stability.

Maternally encoded RNAs and proteins program the early development of all animals. A subset of the maternal transcripts is eliminated from the embryo before the midblastula transition. In certain cases, transcripts are protected from degradation in a subregion of the embryonic cytoplasm, thus resulting in transcript localization. Maternal factors are sufficient for both the degradation and protection components of transcript localization. Cis-acting elements in the RNAs convert transcripts progressively (i) from inherently stable to unstable and (ii) from uniformly degraded to locally protected. Similar mechanisms are likely to act later in development to restrict certain classes of transcripts to particular cell types within somatic cell lineages. Functions of transcript degradation and protection are discussed.

Animals↗
PubMed1977

Cytochrome c: immunofluorescent localization of the testis-specific form.

Mouse testes contain a unique form of cytochrome c. As demonstrated by the indirect immunofluorescence technique, the testis-specific cytochrome c is detectable in the primary spermatocyte and in cell types comprising the later stages of spermatogenesis. Interstitial cells, Sertoli cells, and spermatogonia contain the somatic form of cytochrome c, as does heart muscle.

Animals↗