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PubMed1980

Hodgkin's disease: unfolding concepts concerning its nature, management and prognosis.

The evolution of our concepts concerning the fundamental nature and natural history of Hodgkin's disease is reviewed. Recent evidence establishes that it is indeed a malignant neoplasm, albeit a curious one, the giant cells of which display aneuploid karyotypes, often with marker chromosomes indicating their clonal derivation, and the functional and surface marker properties of cells of the mononuclear phagocyte series. The disease tends initially to spread by contiguity from one lymph node chain to others with which direct lymphatic channel communications exist. Essentially all patients, even those with limited disease, have some degree of impairment of cell-mediated immunity, apparently due to inhibition of T-lymphocyte function. Lymphangiography, computed tomography, and laparotomy with splenectomy have greatly improved the accuracy of clinical staging. Total lymphoid megavoltage radiotherapy and/or multidrug combination chemotherapy now permit the eradiction of disease of all stages, resulting in a dramatic improvement in prognosis and an increasing frequency of permanent cure of this once inevitably fatal condition.

Aneuploidy↗
PubMed1985

Gene amplification: an example of accelerated evolution in tumorigenic cells.

During selection for methotrexate resistance, tumorigenic CHEF/16 cells and derivatives from CHEF/16 tumors underwent amplification of the dihydrofolate reductase gene (DHFR) at accelerated rates compared with closely related nontumorigenic CHEF/18 cells. "Dot blot" analysis showed that the CHEF/16 cells contained many more copies of the DHFR gene than did the CHEF/18 cells, when assayed at similar elevated levels of methotrexate resistance. Chromosome analysis of cell samples taken at several time points during amplification revealed large differences between the nontumorigenic CHEF/18 cells and the two tumorigenic cell lines. The tumorigenic cells developed few chromosome rearrangements over a 4-log increase in methotrexate resistance, other than increased length of a single chromosome, which was shown by in situ hybridization to contain most or all of the amplified DHFR gene copies. In contrast, the CHEF/18 cells underwent complex, progressive changes in almost every chromosome, and in situ hybridization suggested a dispersed pattern of gene amplification. The data support the hypothesis that unregulated amplification is a pathological process, occurring readily in neoplastic but rarely in normal cells, that together with other chromosomal disturbances contributes to the rapid evolution and progression of cancer.

Animals↗
PubMed2007

An oncogenetic tree model in gastrointestinal stromal tumours (GISTs) identifies different pathways of cytogenetic evolution with prognostic implications.

To model the cytogenetic evolution in gastrointestinal stromal tumour (GIST), an oncogenetic tree model was reconstructed using comparative genomic hybridization data from 203 primary GISTs (116 gastric and 87 intestinal GISTs, including 151 newly analysed cases), with follow-up available in 173 cases (mean 40 months; maximum 133 months). The oncogenetic tree model identified three major cytogenetic pathways: one initiated by -14q, one by -1p, and another by -22q. The -14q pathway mainly characterized gastric tumours with predominantly stable karyotypes and more favourable clinical course. On the other hand, the -1p pathway was more characteristic of intestinal GISTs, with an increased capacity for cytogenetic complexity and more aggressive clinical course. Loss of 22q, more closely associated with -1p than -14q, appeared to initiate the critical transition to an unfavourable cytogenetic subpathway. This -22q pathway included accumulation of +8q, -9p, and -9q, which could all predict disease-free survival in addition to tumour site. Thus, insights into the cytogenetic evolution obtained from oncogenetic tree models may eventually help to gain a better understanding of the heterogeneous site-dependent biological behaviour of GISTs.

Chromosome Aberrations↗
PubMed1996

Comparative karyology and evolution of the Amazonian Callithrix (Platyrrhini, Primates).

Chromosomal studies in three species of Amazonian Callithrix (2n=44) and data in the literature show that this group is karyomonotypic. Moreover, it is characterized by the presence of abundant heterochromatic regions, unlike the situation in congeneric forms of Callithrix of the Atlantic coast with 2n=46, and by the presence of a highly repetitive, exclusive DNA component, with a basic repeat motif of 1528bp. Karyotypic comparisons with other Callitrichids and an outgroup species showed that Callitrichids are karyologically conserved and explained several rearrangements that had presumably occurred during their phyletic radiation. Analyses of karyologic data enabled the construction of two alternative phylogenetic topologies. The lack of derived homoeologies, common to all members of the genus Callithrix grouped at present, and the fact that Amazonian species were more similar to Cebuella pygmaea (2n=44) than to their congeneric forms with 2n=46 suggested that species at present included in the Amazonian Callithrix should be grouped with C. pygmaea.

Animals↗
PubMed2003

Amplification of the pericentromeric region of chromosome 1 in a newly established colon carcinoma cell line.

The LRWZ cell line was established from an ascitic effusion of a colon adenocarcinoma. We studied the karyotype of LRWZ cells using G-banding and chromosome painting. The cell line is near triploid and is characterized by several chromosome rearrangements and pronounced intermetaphase variation. Chromosome painting probes revealed numerous labeled regions on different chromosomes, indicating that several translocations occurred during the evolution of the cell population. The 10 recurrent marker chromosomes identified (M1-M10) were derived from complex rearrangements involving up to three different chromosomes. M2 is a particularly interesting marker that originated from the amplification of the pericentromeric region of chromosome 1 and has a peculiar organization comprising five copies of the region included between 1p21 and 1q21 and is surprisingly stable: it is present in all the metaphases analyzed, has telomeric DNA at both termini, and contains one active and four inactivated centromeres. To provide insights into the molecular mechanisms that generated M2, we performed fluorescence in situ hybridization experiments using a panel of probes mapping near the centromere of chromosome 1 and three probes for different satellite sequences; the formation of chromosome M2 required the intervention of several rearrangements including unequal exchange, chromatid breakage followed by fusion of the sister chromatids, and loss of centromeric heterochromatin.

Centromere↗
PubMed2004

Molecular cytogenetic characterization shows higher genetic homogeneity in conventional renal cell carcinoma compared to other kidney cancers.

In this study seven primary kidney tumors out of 13 were cytogenetically characterized by comparative genomic hybridization (CGH) on the surgical specimens as well as by spectral karyotyping (SKY) analysis after short-term culturing. In two of the seven cases only a normal karyotype was identified. Non-clonal aberrations were observed in four of the seven cases. Overall numerical alterations were more frequent than structural changes. The two structural alterations identified constituted of a deletion of the short arm of chromosome 3 in a conventional renal cell carcinoma (RCC), and a ring chromosome derived from chromosome 8 in a papillary RCC. By CGH gains of copy number were revealed on chromosomes 3, 5, 7, 8q, and 20, while the losses encompassed 3p and 17p. In the papillary RCCs only gains were found. Comparison between SKY and CGH data suggests that the conventional RCCs are genetically more homogeneous than the other types of kidney cancer. In the two papillary RCCs, trisomies of chromosomes 7 and 17 were typical findings. In the transitional cell carcinoma different findings by CGH and SKY would suggest that these tumors constitute a heterogeneous population of tumor cells which could represent different steps of somatic evolution of tumors.

Adult↗
PubMedDate not supplied

Accelerated molecular evolution in Microtus (Rodentia) as assessed via complete mitochondrial genome sequences.

Microtus is one of the most taxonomically diverse mammalian genera, including over 60 extant species. These rodents have evolved rapidly, as the genus originated less than 2 million years ago. If these numbers are taken at face value, then an average of 30 microtine speciation events have occurred every million years. One explanation for the rapid rate of cladogenesis in Microtus could be the karyotypic differentiation exhibited across the genus: diploid numbers range from 17 to 64. Despite the striking chromosomal variability within Microtus, phenotypic variation is unremarkable. To determine whether nucleotide substitution rates are also elevated in voles, we sequenced the entire mitochondrial DNA (mtDNA) genome of the Eurasian sibling vole (Microtus rossiaemeridionalis). We compared this genome to another previously sequenced vole mtDNA genome (Microtus kikuchii) and performed pairwise sequence comparisons with the mtDNA genomes of ten additional mammalian genera. We found that microtine mtDNA genomes are evolving more rapidly than any other mammalian lineage we sampled, as gauged by the rate of nucleotide substitution across the entire mtDNA genome as well as at each individual protein-coding gene. Additionally, we compared substitution rates within the cytochrome b gene to seven other rodent genera and found that Microtus mtDNA is evolving fastest. The root cause of accelerated evolution in Microtus remains uncertain, but merits further investigation.

Animals↗
PubMed1976

Robertsonian metacentrics in the mouse.

A survey is given on the occurrence, the geographic origin and the arm composition of 27 Robertsonian fusion metacentric chromosomes of wild populations of the mouse. Their study is of twofold interest: a) it is possible to introduce these naturally occuring metacentrics in laboratory strains for experimental use. At present, altogether 34 metacentric chromosomes of different composition are available including 7 cases of metacentrics known form laboratory strains of the mouse. b) With the search for metacentrics in the mouse and with their identification insights are permitted in the role of Robertsonian changes in the course of mammalian evolution--Several separate populations of the mouse with different sets of multiple (up to 9) metacentrics have been found in Switzerland and Italy. Some of the individual metacentrics may occur in different populations. The participation of an acrocentric autosome in the formation of metacentrics seem to be at random, but the sex chromosomes are never included in a metacentric.--Homology of the arms involved in metacentrics is conserved, so that in meiosis of interpopulation hybrids is due to mechanisms of segregational imbalance and subsequent prenatal elimination of fetal offspring, but it follows also the pattern of male limited hybrid sterility.--From an evolutionary view point, karyotype rearrangements of Robertsonian type may initiate reproductive isolation, which prepares the ground for further genetic diversification and, as in the case of the mouse, of incipient speciation.

Animals↗
PubMed1984

"Masked" Ph1 chromosome abnormalities in CML: a report of two unique cases.

Two patients with chronic myeloid leukemia (CML) showed previously undescribed variants of a "masked" Ph1 abnormality. The first patient had the karyotype 46,XY, + 21, -9, -22, +mar9,mar18 at presentation in the chronic phase. The dicentric marker 9 was interpreted as representing the usual translocation of 22q11 to 9q34, followed by translocation of the Ph1 chromosome (the deleted 22) to 9p and probable translocation of 9p to the distal long arm of the marker. The patient developed clones containing 2 and 3 copies of the "Ph1-containing" marker 9 concomitant with the metamorphosis of his disease to a more aggressive phase. The second case presented with the karyotype 46,XY,-9,-22,+two D-group markers. A complex rearrangement of chromosomes 9 and 22 is postulated, with interstitial insertion of either 9p or distal 9q into chromosome 22q11. This patient is still in the chronic phase of his disease 9 mo after presentation. The common denominator in these unusual "masked" cases is the 22q11 breakpoint. The paucity of published reports of duplication of 9q + without concurrent duplication of the Ph1 chromosome, supported by the findings in our first case, leads us to conclude that the amplification of genes on the Ph1 chromosome are more important for the evolution of the abnormal stem cell in CML than the chromosome 9 derivative.

Adult↗
PubMed2000

Molecular cytogenetic analyses and phylogenetic studies in the Nicotiana section Tomentosae.

Phylogenetic schemes based on changing DNA sequence have made a major impact on our understanding of evolutionary relationships and significantly built on knowledge gained by morphological and anatomical studies. Here we present another approach to phylogeny, using fluorescent in situ hybridisation. The phylogenetic scheme presented is likely to be robust since it is derived from the chromosomal distribution of ten repetitive sequences with different functions and evolutionary constraints [GRS, HRS60, NTRS, the Arabidopsis-type telomere repeat (TTTAGGG)n, 18S-5.8S-26S ribosomal DNA (rDNA), 5S rDNA, and four classes of geminiviral-related DNA (GRD)]. The basic karyotypes of all the plant species investigated Nicotiana tomentosiformis, N. kawakamii, N. tomentosa, N. otophora, N. setchellii, N. glutinosa (all section Tomentosae), and N. tabacum (tobacco, section Genuinae) are similar (x=12) but the distribution of genic and non-genic repeats is quite variable, making the karyotypes distinct. We found sequence dispersal, and locus gain, amplification and loss, all within the regular framework of the basic genomic structure. We predict that the GRD classes of sequence integrated into an ancestral genome only once in the evolution of section Tomentosae and thereafter spread by vertical transmission and speciation into four species. Since GRD is similar to a transgenic construct that was inserted into the N. tabacum genome, its fate over evolutionary time is interesting in the context of the debate on genetically modified organisms and the escape of genes into the wild. Nicotiana tabacum is thought to be an allotetraploid between presumed progenitors of N. sylvestris (maternal, S-genome donor) and a member of section Tomentosae (T-genome donor). Of section Tomentosae, N. tomentosiformis has the most similar genome to the T genome of tobacco and is therefore the most likely paternal genome donor. It is known for N. tabacum that gene conversion has converted most 18S-5.8S-26S rDNA units of N. sylvestris origin into units of an N. tomentosiformis type. Clearly if such a phenomenon were widespread across the genome, genomic in situ hybridisation (GISH) to distinguish the S and T genomes would probably not work since conversion would tend to homogenise the genomes. The fact that GISH does work suggests a limited role for gene conversion in the evolution of N. tabacum.

DNA Probes↗
PubMed1994

Two subclones in a case of uveal melanoma. Relevance of monosomy 3 and multiplication of chromosome 8q.

Monosomy 3 and multiplication of 8q are nonrandom findings in uveal melanoma. We present a case in which two subclones could be detected. Both had monosomy 3 in common. Furthermore, a multiplication of chromosome 8 material was also seen in both subclones. However, it was based on different kinds of aberrations and was accompanied by further anomalies, such as loss of a Y-chromosome, an additional chromosome 7, and an additional marker chromosome, in only one clone. This finding allows some insight into the relevance of the most frequently found anomalies of chromosome 3 and 8 in uveal melanoma. As monosomy 3 occurred before any subclone differentiation, it must be an early, if not primary, event in the genesis of this tumor. Multiplication of chromosome 8, specifically of 8q, however, may contribute to the clonal evolution of this tumor.

Aged↗
PubMed1982

Repetitive DNA and polyploidy in selachians.

1. The DNA reassociation kinetics have been studied in 6 selachian species: Raja asterias, Raja montagui, Dasyatis violacea, Torpedo marmorata, Torpedo ocellata and Oxynotus centrina. 2. The results obtained show that the genomes of the two Torpedo, Dasyatis and Oxynotus are polyploid if compared with those of the two rays, though this finds no correspondence in the diploid chromosome number. 3. The phenomena of polyploidization would often be followed by wide chromosome rearrangements and by a progressive divergence of the various repetitive DNA sequences. 4. The existence of polyploidy in almost all the main superorders of living Selachians suggests that this mechanism of genomic evolution may have played an important role in the phylogeny of this class.

Animals↗
PubMed2003

A cytogenetic study of the leaf beetle genus Cyrtonus (Coleoptera, Chrysomelidae).

The chromosomes of ten species of Cyrtonus and the genome sizes of six are surveyed. Among the total of 15 chromosomally studied species, 11 have 2n = 28 chromosomes and a 13 + Xyp male meioformula, three have 2n = 40 and 19 + Xyp and one 2n = 46 and 22 + Xyp. All but one species with 28 chromosomes show only metacentric or submetacentric chromosomes, whereas the species with 40 and 46 chromosomes display some telocentrics or subtelocentrics, that are probably derived from the former by centric fissions. However, since the number of major chromosome arms is strikingly higher in these latter species (NF = 70 and 78) than in the 28-chromosome species (mostly NF = 56), other chromosomal rearrangements such as pericentric inversions or heterochromatin accretions could also be involved. The genome sizes display a narrow range, from 1C = 0.6-1.22 pg, and they are not significantly correlated with the chromosome numbers. Some possible factors implied in the rough chromosomal evolution of Cyrtonus are discussed in relation to a few other genera of the subfamily Chrysomelinae.

Animals↗
PubMed1986

Cytogenetic "rogue" cells: what is their frequency, origin, and evolutionary significance?

Among 102,170 cultured lymphocytes obtained from 9818 individuals from Hiroshima, Japan, aged 9 to 37 years and scored for chromosomal abnormalities, 24 cells that exhibited an extreme degree of damage were encountered. The damage consists of multiple dicentric and even tricentric chromosomes, as well as numerous fragments, many with the appearance of "double minutes." The occurrence of these cells was not correlated with parental exposure to the atomic bomb, age, sex, year, or season. They were nonrandomly distributed by individual. Such cells were originally described in South American Indians and have also been recorded in inhabitants of the United States and the United Kingdom; this appears to be a world-wide phenomenon. Their cause remains unknown, and it is not known whether they occur in other somatic and germ-line cells. Should the latter be the case and should the least damaged of these cells occasionally successfully complete mitosis and meiosis, the possible role of such cells in oncogenesis and evolution must be considered.

Adolescent↗
PubMed1995

Evolutionary history of New and Old World vultures inferred from nucleotide sequences of the mitochondrial cytochrome b gene.

The phylogeny of 11 species of Old World vultures (Aves: Accipitriformes, Aegypiinae), three species of New World vultures (Cathartidae) and theri nearest relatives within and outside the order Accipitriformes was investigated based on 1026 nucleotides of the mitochondrial cytochrome b gene. The data support the contention that New World vultures are not birds of prey, but phylogenetic information was insufficient to identify whether they are closer to storks (Ciconiidae) or to Accipitriformes. Four species of Gyps are all closely related and probably speciated within the Pleistocene. Molecular data do not support the split of 'white-backed' vultures from Gyps in a separate genus Pseudogyps. The monotypic genera of large, heavy-billed vultures, Aegypius, Torgos, Trigonoceps and Sarcogyps, are of monophyletic origin. We propose to merge Torgos with Aegypius, but retain Trigonoceps and Sarcogyps as separate genera, Sarcogyps being clearly the most primitive of the four. All four, together with Gyps and Necrosyrtes, form a monophyletic subfamily or 'core group', to which the subfamily Aegypiinae should be restricted. This group shares a more recent common ancestor with several non-vulture genera of Accipitrids, among them Buteo, Aquila, Haliaeetus and Circaetus, than it does with the two aberrent vultures Gypaetus barbatus and Neophron percnopterus. The last two are much more primitive; they seem to be each other's sister species and are closer to Pernis than to other Accipitrids. We propose separating Gypaetus and Neophron in the subfamily Gypaetinae. If the cytochrome b gene tree accurately reflects vulture phylogeny, Old World vultures are polyphyletic with the Aegypius-Gyps clade having evolved convergently to the more ancient Gypaetus and Neophron vultures. Polyphyly of Old World vultures, although in conflict with the DNA-DNA hybridization phylogeny of Sibley & Ahlquist (1990), is well supported by molecular, karyotypic, morphological and other phenotypic evidence (behaviour, voice) indicating fundamental differences between the two evolutionary lines.

Americas↗
PubMed1993

Clonal chromosomal abnormalities in Fanconi's anaemia: what do they really mean?

Patients with Fanconi's anaemia (FA) have aplastic anaemia, leukaemia, myelodysplasia and tumours. Since leukaemia has a very poor prognosis, it is desirable to identify high-risk patients. To determine the significance of clonal marrow chromosomal abnormalities we began a prospective study in 17 patients: five were normal, eight aplastic, and four myelodysplastic. Three of 11 with adequate cytogenetics had transient abnormal clones. None had leukaemia at 3-24 months. Changing cytogenetic patterns may not be related to leukaemic evolution in patients with a DNA repair defect.

Chromosome Aberrations↗
PubMed2005

Acute myeloid leukaemia with FLT3 gene mutations of both internal tandem duplication and point mutation type.

FLT3 gene mutations, either internal tandem duplication or point mutation type, are common in acute myeloid leukaemia (AML). We describe 21 AML cases with both types of gene mutations, so-called dual mutations, representing approximately 1% of all cases. Most newly diagnosed AML with FLT3 dual mutations had monocytic differentiation and a normal karyotype. Over the disease course, changes in FLT3 mutation status were seen in 89% of cases, and were associated with cytogenetic changes. We conclude that FLT3 dual mutations occur rarely in AML, and appear to be related to clonal evolution.

Acute Disease↗

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