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Results for “karyotype evolution”

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PubMed1990

Clonal karyotype abnormalities and clinical progress in the myelodysplastic syndrome.

Clonal karyotype abnormalities in 124 patients with myelodysplastic syndrome are reviewed. 36% of patients had abnormalities at referral, the most common being 5q-, +8 and lesions of chromosomes 7 and 20. Reduced survival was associated with the presence of either single or multiple clonal abnormalities at referral, abnormalities of chromosome 7 or 8 (either alone or with other lesions) and exclusively abnormal metaphases. The presence of 5q- alone did not appear to affect survival. Sequential studies were carried out in 77 patients of whom 12 showed karyotypic evolution. Reduced survival was observed in patients with an evolving karyotype but appeared to be due almost entirely to evolution in those patients whose initial karyotype was normal. Leukaemic transformation occurred more commonly in patients with an abnormal karyotype, particularly those with multiple abnormalities, and in patients with an evolving karyotype. Although the first appearance of an abnormal karyotype or an apparent evolution are important phenomena, it is probable that in some cases they merely represent expansion of a previously existing clone that has escaped detection. The distinction between true karyotypic evolution or clonal expansion and statistical variations due to small sample size and variability of samples may be difficult but needs to be taken into account in considering clinical significance.

Adult↗
PubMed1984

Nonrandom chromosomal changes in transitional cell carcinoma of the bladder.

Nine cases of transitional cell carcinoma (eight from the urinary bladder and one from the ureter; six noninvasive and three invasive) were subjected to detailed cytogenetic analysis with a G-banding method. The synchronization of primary cultures with methotrexate for high-resolution banding was performed in five cases. In the remaining four cases, the chromosomes were obtained from short-term cultures after prolonged (16 hr) exposure to Colcemid. Two cases were near-tetraploid, one was hypotriploid, and six were near-diploid (three hyperdiploid and three hypodiploid). All but one case showed various structural abnormalities in the karyotype. The chromosomal changes ranged from the presence of only two abnormal chromosomes (markers) to complex karyotypes with as many as 15 markers. In most tumors, the origin of the marker chromosomes could be readily deciphered. The nonrandom chromosomal aberrations included: (a) an isochrosome of the short arm of chromosome 5 (three cases); (b) monosomy of chromosome 9 found in four cases (this was the sole abnormality in one case); (c) involvement of chromosome 8 as an isochromosome of the long arm (two cases) or loss of the short arm due to deletion (one case) or translocation (one case); and (d) interstitial deletion of chromosome 13 (three cases). Our results indicate that the formation of i(5p) and monosomy 9 may be the primary karyotypic changes in two subgroups of transitional cell carcinoma. Involvement of chromosomes 8 and 13, on the other hand, seems to be a result of secondary karyotypic evolution. Two invasive tumors showed the presence of secondary clones, with additional structural chromosome aberrations superimposed on those already existing in the main cell population. In both cases, the additional aberrations involved the short arm of chromosome 11, resulting in loss of genetic material from the short arm. The short arm of chromosome 11, is the putative site of an oncogene which has been isolated from human bladder carcinoma cell lines. Deletion of the 11p was also seen in one case of noninvasive transitional cell carcinoma localized in the ureter; the material from 11p was probably translocated to chromosome 13. These findings suggest that the loss of genetic material from the short arm of chromosome 11 is a secondary event in the karyotypic evolution of transitional cell carcinoma, probably related to the invasive behavior of the tumor.

Aged↗
PubMed2005

Molecular distinction between true centric fission and pericentric duplication-fission.

Centromere (centric) fission, also known as transverse or lateral centric misdivision, has been defined as the splitting of one functional centromere of a metacentric or submetacentric chromosome to produce two derivative centric chromosomes. It has been observed in a range of organisms and has been ascribed an important role in karyotype evolution; however, the underlying mechanisms remain unknown. We have investigated four cases of apparent centric fission in humans. Two cases show a missing chromosome 22 or 18 that is replaced by two centric ring products, a third case shows two chromosome-10-derived telocentric chromosomes, whereas a fourth case involves the formation of two chromosome-18-derived isochromosomes. In all four cases, results of gross cytogenetic and fluorescence in situ hybridisation analyses were consistent with a simple centric fission event. However, detailed molecular analyses provided evidence in support of centromere duplication as a predisposing mechanism for the observed chromosomal breakage in two of the cases. Results for the third case are consistent with direct centric fission not involving centromere pre-duplication as the likely mechanism. Insufficient material has precluded the further study of the fourth case. The data provide the first molecular evidence for centromere pre-duplication as a possible mechanism to explain the classically assumed simple "centric fission" events in clinical cytogenetics, karyotype evolution and speciation.

Fluorescent Antibody Technique↗
PubMed1995

ZOO-FISH analysis: cat and human karyotypes closely resemble the putative ancestral mammalian karyotype.

DNA in situ hybridization with human chromosome specific DNA libraries was applied to compare the karyotypes of humans (Homo sapiens, 2n = 46) and cats (Felis catus, 2n = 38). For the autosomes alone, 30 segments of conserved synteny were revealed. The arrangement of these segments in the feline karyotype differs by only seven single chromosome breaks and one intrachromosomal inversion from their arrangement in humans. Comparison of these data with those recently obtained for pig and those available from conventional gene mapping studies in mice and cattle has allowed us to develop a model of karyotype evolution in mammals. The cat and human karyotypes, with 36 and 44 autosomes respectively, were found to be very similar to a putative ancient mammalian founder karyotype. It would appear that during evolution to the human karyotype the status quo has been conserved for at least some 100-120 million years. There has been no need to alter the well-balanced gene arrangement of the mammalian founder karyotype.

Animals↗
PubMed1979

Evolution of karyotypes in Philadelphia (Ph1) chromosome-negative chronic myelogenous leukemia.

Ten of 55 patients with chronic myelogenous leukemia (CML) diagnosed between 1972 and 1977 were found to lack the Philadelphia (Ph1) chromosome. Serial clinical, morphologic, and cytogenetic studies of patients with Ph1-negative CML showed that 30% of them had chromosomal abnormalities. Two had an extra chromosome No. 8 at the time of blast crisis, with a morphological picture of myeloblasts in the bone marrow. A third patient had a 6:14 translocation initially Abnormalities of chromosome No. 14 are frequently seen in lymphoproliferative disorders, and the bone marrow and peripheral blood contained a significant population of lymphoblasts as well as myeloblasts. The median survival for the 10 patients was 19 months. The exact nature of Ph1-negative CML is not yet clear; disease appears to be a distinct entity among the myeloproliferative disorders.

Aged↗
PubMed1984

Chromosome relationships in the genus Salmo.

Chromosome numbers and polymorphisms in rainbow trout, Atlantic salmon, and brown trout are described. The karyotypes of these three species are compared with each other and with those of other salmonid fish from the genera Salmo, Salvelinus, and Oncorhynchus. Karyotype evolution from a postulated ancestral tetraploid is discussed.

Animals↗
PubMed1985

Evolution of karyotypic abnormalities and C-MYC oncogene amplification in human colonic carcinoma cell lines.

Cell lines (COLO 320 DM and COLO 320 HSR), established from a human neuroendocrine tumor, contain an amplified cellular oncogene (c-myc). We have previously shown that the homogeneously staining regions (HSRs) of a marker chromosome in the COLO 320 HSR cells that evolved in culture from COLO 320 DM cells contain amplified c-myc. Molecular hybridization in situ has now been used to demonstrate that the HSRs are on both arms of what was once an X chromosome. We also show that amplified c-myc copies are present in the isolated double minute chromosomes (DMs) of the COLO 320 DM cells that were characteristic of the tumor cells initially established from the patient. The results suggest that the amplified c-myc appeared first as DMs and was subsequently transposed to engender HSRs on an X chromosome. The initial COLO 320 tumor cell may have acquired two "early replicating" (i.e., active) X chromosomes and lost the "late replicating" (i.e., inactive) X.

Cell Line↗
PubMed1983

Familial leukemia and aplastic anemia associated with monosomy 7.

A kindred is described in which eight of 14 patients in one generation had acute nonlymphocytic leukemia or aplastic anemia either alone or terminating in acute nonlymphocytic leukemia. The proband and two siblings in one branch of this kindred presented with aplastic anemia, whereas acute nonlymphocytic leukemia was the presenting feature in the other two branches. Karyotypic evolution from a normal karyotype to monosomy 7 was demonstrated in the proband, and group C monosomy was seen in two other patients. The proband's serum sample inhibited in vitro growth of normal bone marrow colonies. The occurrence of hematologic disease in this kindred appears to be the result of a maternally transmitted trait, and persons younger than 30 years of age appear to have the highest risk of hematologic disease.

Adolescent↗
PubMed1982

Clonal evolution of karyotype in blastic phase of CML.

A patient with chronic myelocytic leukemia (CML) had a Philadelphia chromosome--Ph1(t(9q +; 22q--)) in all evaluated bone marrow cells at the time of diagnosis. After 29 months of intermittent therapy (chemotherapy and immunotherapy) and 2 months before clinical signs of blastic phase developed, three additional cell lines in bone marrow and peripheral blood appeared: one line with extra chromosome Ph1, another one in which chromosome Y disappeared, and the third line with extra chromosome No. 13, evidently derived from the X-monosomie cell line. Five weeks before death a variable hypodiploidy was found in more than 50% mitoses. The patient died 47 months after the establishment of CML and seven months after the onset of the blastic phase.

Chromosome Aberrations↗
PubMed2004

Phylogeny of Agrodiaetus Hübner 1822 (Lepidoptera: Lycaenidae) inferred from mtDNA sequences of COI and COII and nuclear sequences of EF1-alpha: karyotype diversification and species radiation.

Butterflies in the large Palearctic genus Agrodiaetus (Lepidoptera: Lycaenidae) are extremely uniform and exhibit few distinguishing morphological characters. However, these insects are distinctive in one respect: as a group they possess among the greatest interspecific karyotype diversity in the animal kingdom, with chromosome numbers (n) ranging from 10 to 125. The monophyly of Agrodiaetus and its systematic position relative to other groups within the section Polyommatus have been controversial. Characters from the mitochondrial genes for cytochrome oxidases I and II and from the nuclear gene for elongation factor 1 alpha were used to reconstruct the phylogeny of Agrodiaetus using maximum parsimony and Bayesian phylogenetic methods. Ninety-one individuals, encompassing most of the taxonomic diversity of Agrodiaetus, and representatives of 14 related genera were included in this analysis. Our data indicate that Agrodiaetus is monophyletic. Representatives of the genus Polyommatus (sensu stricto) are the closest relatives. The sequences of the Agrodiaetus taxa in this analysis are tentatively arranged into 12 clades, only 1 of which corresponds to a species group traditionally recognized in Agrodiaetus. Heterogeneous substitution rates across a recovered topology were homogenized with a nonparametric rate-smoothing algorithm before the application of a molecular clock. Two published estimates of substitution rates dated the origin of Agrodiaetus between 2.51 and 3.85 million years ago. During this time, there was heterogeneity in the rate and direction of karyotype evolution among lineages within the genus. Karyotype instability has evolved independently three times in the section Polyommatus, within the lineages Agrodiaetus, Lysandra, and Plebicula. Rapid karyotype diversification may have played a significant role in the radiation of the genus Agrodiaetus.

Animals↗
PubMed2005

Breakpoint analysis of the pericentric inversion between chimpanzee chromosome 10 and the homologous chromosome 12 in humans.

During this study, we analysed the pericentric inversion that distinguishes human chromosome 12 (HSA12) from the homologous chimpanzee chromosome (PTR10). Two large chimpanzee-specific duplications of 86 and 23 kb were observed in the breakpoint regions, which most probably occurred associated with the inversion. The inversion break in PTR10p caused the disruption of the SLCO1B3 gene in exon 11. However, the 86-kb duplication includes the functional SLCO1B3 locus, which is thus retained in the chimpanzee, although inverted to PTR10q. The second duplication spans 23 kb and does not contain expressed sequences. Eleven genes map to a region of about 1 Mb around the breakpoints. Six of these eleven genes are not among the differentially expressed genes as determined previously by comparing the human and chimpanzee transcriptome of fibroblast cell lines, blood leukocytes, liver and brain samples. These findings imply that the inversion did not cause major expression differences of these genes. Comparative FISH analysis with BACs spanning the inversion breakpoints in PTR on metaphase chromosomes of gorilla (GGO) confirmed that the pericentric inversion of the chromosome 12 homologs in GGO and PTR have distinct breakpoints and that humans retain the ancestral arrangement. These findings coincide with the trend observed in hominoid karyotype evolution that humans have a karyotype close to an ancestral one, while African great apes present with more derived chromosome arrangements.

Animals↗
PubMed2000

Aneuploidy vs. gene mutation hypothesis of cancer: recent study claims mutation but is found to support aneuploidy.

For nearly a century, cancer has been blamed on somatic mutation. But it is still unclear whether this mutation is aneuploidy, an abnormal balance of chromosomes, or gene mutation. Despite enormous efforts, the currently popular gene mutation hypothesis has failed to identify cancer-specific mutations with transforming function and cannot explain why cancer occurs only many months to decades after mutation by carcinogens and why solid cancers are aneuploid, although conventional mutation does not depend on karyotype alteration. A recent high-profile publication now claims to have solved these discrepancies with a set of three synthetic mutant genes that "suffices to convert normal human cells into tumorigenic cells." However, we show here that even this study failed to explain why it took more than "60 population doublings" from the introduction of the first of these genes, a derivative of the tumor antigen of simian virus 40 tumor virus, to generate tumor cells, why the tumor cells were clonal although gene transfer was polyclonal, and above all, why the tumor cells were aneuploid. If aneuploidy is assumed to be the somatic mutation that causes cancer, all these results can be explained. The aneuploidy hypothesis predicts the long latent periods and the clonality on the basis of the following two-stage mechanism: stage one, a carcinogen (or mutant gene) generates aneuploidy; stage two, aneuploidy destabilizes the karyotype and thus initiates an autocatalytic karyotype evolution generating preneoplastic and eventually neoplastic karyotypes. Because the odds are very low that an abnormal karyotype will surpass the viability of a normal diploid cell, the evolution of a neoplastic cell species is slow and thus clonal, which is comparable to conventional evolution of new species.

Aneuploidy↗
PubMed2003

Characterization of ancestral chromosome fusion points in the Indian muntjac deer.

Tandem fusion, a rare evolutionary chromosome rearrangement, has occurred extensively in muntjac karyotypic evolution, leading to an extreme fusion karyotype of 6/7 (female/male) chromosomes in the Indian muntjac. These fusion chromosomes contain numerous ancestral chromosomal break and fusion points. Here, we designed a composite polymerase chain reaction (PCR) strategy which recovered DNA fragments that contained telomere and muntjac satellite DNA sequence repeats. Nested PCR confirmed the specificity of the products. Two-color fluorescence in situ hybridization (FISH) with the repetitive sequences obtained and T2AG3 telomere probes showed co-localization of satellite and telomere sequences in Indian muntjac chromosomes. Adjacent telomere and muntjac satellite sequences were also seen by fiber FISH. These data lend support to the involvement of telomere and GC-rich satellite DNA sequences during muntjac chromosome fusions.

Animals↗
PubMed2006

Strategies of karyotype differentiation in Elateridae (Coleoptera, Polyphaga).

The chromosome study of five species of the family Elateridae, belonging to the subfamilies Agrypninae and Elaterinae, and the analysis of the cytogenetic data previously recorded for this family permitted the establishment of the main strategies of karyotypic differentiation that has occurred in the elaterids. In Agrypninae, the three species studied (Conoderus fuscofasciatus, Conoderus rufidens, and Conoderus sp.) showed the male karyotype 2n=16+X0. This karyotypic uniformity detected in these Conoderus species has also been shared with other species of the same genus, differing considerably from chromosomal heterogeneity verified in the subfamily Agrypninae. The use of the C-banding technique in C. fuscofasciatus and Conoderus sp. revealed constitutive heterochromatin in the pericentromeric region of the majority of the chromosomes. In C. fuscofasciatus, additional constitutive heterochromatin were also observed in the long arm terminal region of almost all chromosomes. Among the representatives of Elaterinae, the karyotype 2n=18+Xy(p) of Pomachilius sp.2 was similar to that verified in the majority of the Coleoptera species, contrasting with the chromosomal formula 2n=18+X0 detected in Cardiorhinus rufilateris, which is most common in the species of Elaterinae. In the majority of the elaterids, the chromosomal differentiation has frequently been driven by reduction of the diploid number; but, among the four cytogenetically examined subfamilies, there are some differences in relation to the trends of karyotypic evolution.

Animals↗
PubMed2003

Replication banding in two Mediterranean moray eels: chromosomal characterization and comparison.

Early and late replication bandings have been obtained by in vitro BrdU incorporation in the Mediterranean Muraenidae species Muraena helena and Gymnothorax unicolor, and used to characterize their karyotypes. A comparative analysis of the banding patterns allowed to point out high karyotype similarity as well as chromosome rearrangements that occurred in karyotype evolution between these species.

Animals↗