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At least 955 records · Page 53Linked to original sources
PubMed1996

Developmental Aspects of Immunoglobulins and Antibodies.

This short review discusses the evolution of the immunoglobulins and the development of the diversity of antibodies. Birds and mammals represent two lines of development having divided more than 300 million years ago. In the immunoglobulins and antibody-systems there are many similarities which, however, are based on analogies. In this sense the dominant humoral type of immunoglobulin is IgY in birds and opposed to IgG in the mammals. Also, the mechanisms differ which lead to the diversity of antibodies. In mammals predominantly recombination of gen-segments and somatic mutations lead to this diversity, in birds gen-conversion shows a greater significance. In this way comparable results are produced through different structures or mechanisms.

Journal Article↗
PubMed1988

The left end of rat L1 (L1Rn, long interspersed repeated) DNA which is a CpG island can function as a promoter.

Here we report that the 600 bp promoter-like region at the left end of a newly isolated and characterized rat L1 DNA element can activate the prokaryotic chloramphenicol acyltransferase gene in a rat cell line. Activation only occurs when the promoter region is oriented to the transferase gene as it is to the L1 protein encoding sequences and is 75% inhibited by methylation of just 5 of the 22 CpGs present in the promoter. The G + C rich promoter contains enough CpGs to qualify it as a CpG island, but in contrast to other CpG islands, genomic L1 promoters are fully methylated in both somatic cell and sperm DNA as judged by restriction enzyme analysis. Partial demethylation of the genomic promoters by treatment with 5-azacytidine failed to produce discrete L1 transcripts. The relationship of methylation to the evolutionary history and fate of the rat L1 promoter is discussed.

Animals↗
PubMed1995

Cloning and regional assignment of the human myosin heavy chain 12 (MYH12) gene to chromosome band 15q21.

Sequences encoding 1,235 bp of the human myosin heavy chain 12 (MYH12) gene have been cloned from a human brain cDNA library by PCR amplification. The human sequence is 95.8% identical to the mouse sequence at the amino acid level, indicating that the MYH12 gene has been evolutionarily well conserved. Somatic cell hybrid analysis and in situ hybridization place the MYH12 gene on human chromosome 15, at band q21, and extend distally the known region of chromosome 15 linkage homology on mouse chromosome 9.

Amino Acid Sequence↗
PubMed1994

mtDNA and the origin of Caucasians: identification of ancient Caucasian-specific haplogroups, one of which is prone to a recurrent somatic duplication in the D-loop region.

mtDNA sequence variation was examined in 175 Caucasians from the United States and Canada by PCR amplification and high-resolution restriction-endonuclease analysis. The majority of the Caucasian mtDNAs were subsumed within four mtDNA lineages (haplogroups) defined by mutations that are rarely seen in Africans and Mongoloids. The sequence divergence of these haplogroups indicates that they arose early in Caucasian radiation and gave raise to modern European mtDNAs. Although ancient, none of these haplogroups is old enough to be compatible with a Neanderthal origin, suggesting that Homo sapiens sapiens displaced H. s. neanderthaliensis, rather than mixed with it. The mtDNAs of one of these haplogroups have a unique homoplasmic insertion between nucleotide pair (np) 573 and np 574, within the D-loop control region. This insertion makes these mtDNAs prone to a somatic mutation that duplicates a 270-bp portion of the D-loop region between np 309 and np 572. This finding suggests that certain nonpathogenic mtDNA mutations could predispose individuals to mtDNA rearrangements.

Animals↗
PubMed2003

Selective expression of beta tubulin isotypes in gerbil vestibular sensory epithelia and neurons.

The seven mammalian isotypes of beta tubulin are strikingly similar in amino acid sequence. The differences in isotypic sequence, although small, are nonetheless conserved in evolution, which suggests that they may confer distinct functional roles. If so, such roles should be reflected in the selective expression of isotypes by cell type, or even in the sorting of isotypes to within-cell pools. Hair cells of the vestibular sensory epithelia each possess a kinocilium, a microtubule-based organelle that could represent a distinct microtubule compartment, separate from the extensive microtubule network in the soma. The afferent neurons that innervate the vestibular sensory epithelia may also be functionally divided into dendritic, somatic, and axonal compartments, each with its own complement of microtubules. We have examined the distribution of beta tubulin isotypes in gerbil vestibular epithelia using isotype-specific antibodies to four isotypes and indirect immunofluorescence. We found that hair cells selectively express betaI and betaIV tubulin, while supporting cells express betaI, betaII, and betaIV tubulin. However, no sorting of isotypes between somatic and kinocilia compartments was found in hair cells. Vestibular ganglion cells display three isotypes in the soma, axon, and terminal dendrite compartments (betaI, betaII, and betaIII tubulin), but only betaIII tubulin was found in calyceal nerve endings. The implication of these findings is that beta tubulin isotypes are not sorted to within-cell compartments in hair cells but are sorted in some vestibular neurons.

Animals↗
PubMed1997

Localization of the fast skeletal muscle troponin I gene (TNNI2) to 11p15.5: genes for troponin I and T are organized in pairs.

We have localized the gene encoding the fast skeletal muscle isoform of troponin I (TNNI2) to 11p15.5 by PCR-based analysis of somatic cell hybrid panels: based on the Genebridge4 radiation hybrid panel, TNNI2 is coincident with the marker D11S922. The gene encoding the fast skeletal muscle troponin T gene (TNNT3) has been previously assigned to 11p15.5 suggesting that TNNI2 and TNNT3 may be closely linked. The overall location of genes encoding troponin I and T isoforms now reveals that they are organized at three loci each containing a troponin I/troponin T gene pair. This organization contrasts with all other sarcomeric protein genes and has implications for the evolution of these two gene families, for their regulation and for the analysis of mutations suspected to result in cardiomyopathy.

Biomarkers↗
PubMed1996

Somatic microsatellite mutations as molecular tumor clocks.

Microsatellite (MS) mutations can potentially unravel the past of mutator phenotype tumors, with greater genetic diversity expected in older regions. Rapid clonal expansions of xenografts were characterized by relatively homogenous MS alleles, whereas greater diversity was observed in a colorectal cancer with the greatest variation in its adjacent adenoma. A subcutaneous lung cancer metastasis demonstrated diversity consistent with its one-month clinical duration and evidence of active mitosis during dormancy. The genetic legacy inherent to multistep tumorigenesis provides direct estimates of tumor ages, with up to thousands of cell divisions and high death rates necessary to yield the observed diversities. MS molecular tumor clocks have the unique potential to systematically reconstruct the early and occult evolution of individual human mutator phenotype tumors.

Adenocarcinoma↗
PubMed1999

Lineage selection and the evolution of multistage carcinogenesis.

A wide array of proto-oncogenes and tumour suppressor genes are involved in the prevention of cancer. Each form of cancer requires mutations in a characteristic group of genes, but no single group controls all cancers. This lack of generality shows that the control of cancer is not an ancient, fixed property of cells. By contrast, it supports a dynamic evolutionary model, whereby genetic controls over unregulated cell growth are recruited independently through evolutionary time in different tissues within different taxa. The complexity of this genetic control can be predicted from a population genetic model of lineage selection driven by the detrimental fitness effects of cancer. Cancer occurs because the genetic control of cell growth is vulnerable to somatic mutations (or 'hits'), particularly in large, continuously dividing tissues. Thus, compared to small rodents, humans must have evolved more complex genetic controls over cell growth in at least some of their tissues because of their greater size and longevity; an expectation relevant to the application of mouse data to humans. Similarly, the 'two-hit' model so successfully applied to retinoblastoma, which originates in a small embryonic tissue, is unlikely to be generally applicable to other human cancers; instead, more complex scenarios are expected to dominate, with complexity depending upon a tissue's size and its pattern of proliferation.

Animals↗
PubMed2005

Psychiatric comorbidity and chronicisation in primary headache.

The frequent association between primary headaches and psychiatric disorders is consistently reported in the literature. There is increasing evidence that a bi-directional relationship links these somatic conditions to psychopathological events. Prospective studies show that several psychiatric disorders are severe risk factors for both the onset and chronicisation of primary headache, and for a long time it has been suspected that headache triggers psychiatric disorders, mostly of affective nature, and affects both their course and outcome. Researchers are actively involved in investigating the biological basis of such a relationship while clinicians still need to strengthen their interest in psychiatric comorbidity of their primary headache patients to improve clinical outcome and to prevent chronic evolutions.

Anxiety Disorders↗
PubMed1989

DNA, mutations and aging.

Genetic instability is widely thought to be involved in the process of aging. Evolutionary theory suggests that aging may well result from stochastic damage to DNA. However, studies of the dynamics of accumulation of simple somatic mutations have shown that such a mechanism cannot readily account for experimental observations. A more complex mutational theory of aging is emerging which allows for interaction between mutations, for damage to epigenetic controls on gene expression, and for interaction of (epi)genetic changes with other possible molecular events contributing to aging.

Aging↗
PubMed1991

The human Hb (mu) class glutathione S-transferases are encoded by a dispersed gene family.

The human glutathione S-transferases are products of a gene superfamily which consists of at least four gene families. The various glutathione S-transferase genes are located on different human chromosomes, and new gene(s) are still being added to the gene superfamily. We have characterized a cDNA in pGTH4 encoding human glutathione S-transferase subunit 4 (GST mu) and mapped its gene (or a homologous family member) on chromosome 1 at p31 by in situ hybridization. Genomic Southern analysis with the 3' noncoding region of the cDNA revealed at least four human DNA fragments with highly homologous sequences. Using a panel of DNAs from mouse-human somatic cell hybrids in genomic DNA hybridization we show that the Hb (or B) genes of human glutathione S-transferases are on three separate chromosomes: 1, 6, and 13. Therefore, the glutathione S-transferase B gene family, which encodes the Hb (mu) class subunits, is a dispersed gene family. The GST mu (psi) gene, whose expression is polymorphic in the human population, is probably located on chromosome 13. We propose that the GST mu (psi) gene was created by a transposition or recombination event during evolution. The null phenotype may have resulted from a lack of DNA transposition just as much as from the deletion of an inserted gene.

Animals↗
PubMed2004

Measuring vertebrate telomeres: applications and limitations.

Telomeres are short tandem repeated sequences of DNA found at the ends of eukaryotic chromosomes that function in stabilizing chromosomal end integrity. In vivo studies of somatic tissue of mammals and birds have shown a correlation between telomere length and organismal age within species, and correlations between telomere shortening rate and lifespan among species. This result presents the tantalizing possibility that telomere length could be used to provide much needed information on age, ageing and survival in natural populations where longitudinal studies are lacking. Here we review methods available for measuring telomere length and discuss the potential uses and limitations of telomeres as age and ageing estimators in the fields of vertebrate ecology, evolution and conservation.

Aging↗
PubMed2003

The ADAMs family of proteins: from basic studies to potential clinical applications.

The ADAMs are a family of membrane proteins possessing a disintegrin and metalloprotease domain. Currently, 34 members are known to exist. Approximately 50% of the ADAMs contain a metalloprotease-like domain and some of these have been shown to possess protease activity. Most of the protein substrates identified to date for ADAMs are either integral membrane or extracellular matrix (ECM) proteins. In addition to hydrolysing proteins, a number of ADAMs bind to integrins. The attachment to integrins occurs via the disintegrin domain. Since the ADAMs can play a role in both proteolysis and adhesion, they have been implicated in a variety of biological processes such as sperm-egg fusion, somatic cell-cell adhesion, ectodomain shedding, myoblast fusion and development. Altered expression of certain ADAMs has been associated with a number of diseases including asthma, arthritis, Alzheimer's disease, atherosclerosis and cancer.

Alzheimer Disease↗
PubMedDate not supplied

[Disorders in molecular organization of erythrocyte membrane in patients with somatic and mental pathology].

The article describes general laws and peculiarities of structural and functional changes of erythrocyte's membrane in patients with somatic and mental pathology. Considering our own investigations and reports in medical journals, conclusions are made supposing an existence of typical molecular disorders of erythrocyte membrane in pathological process of different genesis. It is suggested that a universal reaction of circulating pool of erythrocytes on different pathological affects is evolutionary formed.

Biological Evolution↗
PubMed2006

Nonrandom distribution of genes with sex-biased expression in the chicken genome.

Evolutionary theory predicts that sexually antagonistic genes should show a nonrandom genomic distribution with sex chromosomes usually being enriched for such genes. However, empirical observations from model organisms (Drosophila melanogaster, Caenorhabditis elegans, mammals) on the genomic location of genes with sex-biased expression have provided conflicting data and are not easily explained by a unified framework based on standard models of the evolution of sexually antagonistic genes. Previous studies have been confined to organisms with male heterogamety, meaning that effects related to homo- or heterozygosity of sex chromosomes cannot be separated from effects related to sex-specific characteristics. We therefore studied the genomic distribution of genes with sex-biased expression in the chicken, that is, in an organism with female heterogamety (males ZZ, females ZW). From the abundance of transcripts in expressed sequence tag libraries, we found an underrepresentation of female-specific genes (germ line and somatic tissue) and an overrepresentation of male-specific genes (somatic) on the Z chromosome. This is consistent with theoretical predictions only if mutations beneficial to one sex generally tend to be at least partly dominant (h > 0.5). We also note that sexual selection for a male-biased trait is facilitated by Z-linkage, because sons in organisms with female heterogamety will always inherit a Z chromosome from their fathers.

Animals↗
PubMed2005

Genome-wide identification of female-enriched genes in zebrafish.

Characteristic differences in morphology, physiology, and behavior between a male and female are correlated to the differential selection of sex-dependent transcriptomes. By using a cDNA array carrying approximately 9,000 zebrafish unique genes, we identified a group of genes whose expression are enriched in the female fish. A subset of these genes have been confirmed and further grouped as egg-enriched genes, as both somatic- and egg-enriched genes or as somatic-enriched genes by means of RNA gel blot hybridization. Most importantly, a significant proportion of these genes are either functionally unknown or are novel genes. Thus, future studies of this group of genes will help us greatly to understand more about sex-determination and sex-related physiology and behavior. In addition, comparison of zebrafish female-enriched genes with that in Drosophila, we found that only germline genes are shared between vertebrate and invertebrate, suggesting that the process of oogenesis is highly conserved during the evolution.

Animals↗
PubMed2006

Ollier disease.

Enchondromas are common intraosseous, usually benign cartilaginous tumors, that develop in close proximity to growth plate cartilage. When multiple enchondromas are present, the condition is called enchondromatosis also known as Ollier disease (WHO terminology). The estimated prevalence of Ollier disease is 1/100,000. Clinical manifestations often appear in the first decade of life. Ollier disease is characterized by an asymmetric distribution of cartilage lesions and these can be extremely variable (in terms of size, number, location, evolution of enchondromas, age of onset and of diagnosis, requirement for surgery). Clinical problems caused by enchondromas include skeletal deformities, limb-length discrepancy, and the potential risk for malignant change to chondrosarcoma. The condition in which multiple enchondromatosis is associated with soft tissue hemangiomas is known as Maffucci syndrome. Until now both Ollier disease and Maffucci syndrome have only occurred in isolated patients and not familial. It remains uncertain whether the disorder is caused by a single gene defect or by combinations of (germ-line and/or somatic) mutations. The diagnosis is based on clinical and conventional radiological evaluations. Histological analysis has a limited role and is mainly used if malignancy is suspected. There is no medical treatment for enchondromatosis. Surgery is indicated in case of complications (pathological fractures, growth defect, malignant transformation). The prognosis for Ollier disease is difficult to assess. As is generally the case, forms with an early onset appear more severe. Enchondromas in Ollier disease present a risk of malignant transformation of enchondromas into chondrosarcomas.

Chondrosarcoma↗
PubMed2006

Are programmable freezers still needed in the embryo laboratory? Review on vitrification.

The predictable answer to the provocative question of whether programmable freezers are still needed in the embryo laboratory is an even more provocative 'no'. However, such a radical statement needs strong support. Based on the extensive literature of the past 5 years, the authors collected arguments either supporting or contradicting their opinion. After an overview of the causes of cryoinjuries and strategies to eliminate them, the evolution of vitrification methods is discussed. Special attention is paid to the biosafety issues. The authors did not find any circumstance in oocyte or embryo cryopreservation where slow freezing offers considerable advantages compared with vitrification. In contrast, the overwhelming majority of published data prove that the latest vitrification methods are more efficient and reliable than any version of slow freezing. Application of the proper vitrification methods increases the efficiency of long-term storage of stem cells and opens new perspectives in cryopreservation of oocytes, both for IVF and somatic cell nuclear transfer. However, lack of support from regulatory authorities, and conservative approachs regarding novel techniques can slow down the implementation of vitrification. The opinion of the authors is that vitrification is the future of cryopreservation. The public have the final say in whether they want and allow this future to arrive.

Animals↗