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PubMed2002

Karyotype instability between diagnosis and relapse in 117 patients with acute myeloid leukemia: implications for resistance against therapy.

The instability of the karyotype may play a role in the development of refractoriness of acute myeloid leukemia (AML) to anti-leukemic therapy. Therefore, in the current study cytogenetic analyses were performed in 117 patients with AML both at diagnosis and at relapse. Changes in karyotype were observed in 38% (36% of initially normal karyotypes, 39% of initially aberrant karyotypes). An evolution of karyotype, ie the acquisition of further aberrations in addition to those present at diagnosis, occurred more frequently in patients with unfavorable karyotypes at diagnosis as compared to all others (60% vs 32%, P = 0.0095). The duration from initial diagnosis to relapse was significantly shorter in cases with an evolution of the aberrant karyotype as compared to cases with no changes in the aberrant karyotype between diagnosis and relapse or with solely regression of aberrations at relapse (9.2 +/- 4.4 vs14.0 +/- 8.5 months, P = 0.0081). In an additional analysis, another cohort of 120 patients with refractory and relapsed AML who were treated uniformly within the respective trial of the German AML Cooperative Group was analyzed cytogenetically at diagnosis and at relapse to further prove the prognostic impact of karyotype aberrations at relapse. Karyotypes were prognostically favorable, intermediate, unfavorable and not available in 8%, 50%, 17% and 25% at diagnosis and in 8%, 49%, 21% and 22% at relapse, respectively. Karyotype aberrations at diagnosis had no impact on response to therapy (P = 0.32) but influenced survival and event-free survival significantly (P = 0.03 and P = 0.02). In contrast, karyotype aberrations at relapse strongly influenced response to therapy (P = 0.05), survival (P = 0.01), and event-free survival (P = 0.002). These data suggest that the instability of the karyotype between diagnosis and relapse and thus karyotype aberrations at relapse in particular contribute to the refractoriness of AML to anti-leukemic therapy.

Acute Disease↗
PubMed2006

Cancer progression by non-clonal chromosome aberrations.

The establishment of the correct conceptual framework is vital to any scientific discipline including cancer research. Influenced by hematologic cancer studies, the current cancer concept focuses on the stepwise patterns of progression as defined by specific recurrent genetic aberrations. This concept has faced a tough challenge as the majority of cancer cases follow non-linear patterns and display stochastic progression. In light of the recent discovery that genomic instability is directly linked to stochastic non-clonal chromosome aberrations (NCCAs), and that cancer progression can be characterized as a dynamic relationship between NCCAs and recurrent clonal chromosome aberrations (CCAs), we propose that the dynamics of NCCAs is a key element for karyotypic evolution in solid tumors. To support this viewpoint, we briefly discuss various basic elements responsible for cancer initiation and progression within an evolutionary context. We argue that even though stochastic changes can be detected at various levels of genetic organization, such as at the gene level and epigenetic level, it is primarily detected at the chromosomal or genome level. Thus, NCCA-mediated genomic variation plays a dominant role in cancer progression. To further illustrate the involvement of NCCA/CCA cycles in the pattern of cancer evolution, four cancer evolutionary models have been proposed based on the comparative analysis of karyotype patterns of various types of cancer.

Animals↗
PubMed1990

Distribution of non-telomeric sites of the (TTAGGG)n telomeric sequence in vertebrate chromosomes.

The intrachromosomal distribution of non-telomeric sites of the (TTAGGG)n telomeric repeat was determined for 100 vertebrate species. The most common non-telomeric location of this sequence was in the pericentric regions of chromosomes. A variety of species showed relatively large amounts of this sequence present within regions of constitutive heterochromatin. We discuss possible relationships between the non-telomeric distribution of the (TTAGGG)n sequence and the process of karyotype evolution, during which these sites may provide potential new telomeres.

Amphibians↗
PubMed2005

Comparative molecular cytogenetic analysis of two congeneric species, Mugil curema and M. liza (Pisces, Mugiliformes), characterized by significant karyotype diversity.

Two congeneric mullet species, Mugil liza and M. curema, respectively with an all-uniarmed and an all-biarmed karyotype, were cytogenetically studied by base-specific fluorochrome staining and FISH-mapping of 45S and 5S ribosomal RNA genes (rDNA) and the (TTAGGG)(n) telomeric repeats. Whereas 45S rDNA sites might be homeologus in the two species, 5S rDNA sites are not, as they are localized on chromosome arms of different size. In both species, the (TTAGGG)(n) telomeric probe hybridized to natural telomeres and was found scattered along the NORs. In metacentric chromosomes of M. curema, no pericentromeric signals of the telomeric probe were detected. Data are discussed in relation to the karyotype evolution in Mugilidae and to the mechanisms and the evolutionary implications of Robertsonian rearrangements in M. curema.

Animals↗
PubMed1999

Chromosomal localization of 5S rDNA genes in Leporinus fish (Anostomidae, Characiformes).

The large 45S rDNA chromosome sites have often been analyzed in fish. In contrast, little is known about the 5S genes in this animal group. In the genus Leporinus, the NOR chromosomal location has been shown to be very diverse. In the present work, chromosome mapping of 5S rDNA in three anostomids, Leporinus elongatus, L. obtusidens and L. friderici, is investigated using fluorescence in-situ hybridization (FISH) with PCR-obtained 5S probes and primed in-situ labeling (PRINS). Major 5S rDNA chromosomal sites were found to be subterminally located in a small metacentric pair, while minor ones were detected near the centromeric region of a medium-sized submetacentric pair in all studied species. The 5S rDNA genes were not associated with the NORs or sex chromosomes. A highly conserved chromosomal location of these genes appears to characterize the karyotype evolution of this fish group.

Animals↗
PubMed2005

Retention of latent centromeres in the Mammalian genome.

The centromere is a cytologically defined entity that possesses a conserved and restricted function in the cell: it is the site of kinetochore assembly and spindle attachment. Despite its conserved function, the centromere is a highly mutable portion of the chromosome, carrying little sequence conservation across taxa. This divergence has made studying the movement of a centromere, either within a single karyotype or between species, a challenging endeavor. Several hypotheses have been proposed to explain the permutability of centromere location within a chromosome. This permutability is termed "centromere repositioning" when described in an evolutionary context and "neocentromerization" when abnormalities within an individual karyotype are considered. Both are characterized by a shift in location of the functional centromere within a chromosome without a concomitant change in linear gene order. Evolutionary studies across lineages clearly indicate that centromere repositioning is not a rare event in karyotypic evolution and must be considered when examining the evolution of chromosome structure and syntenic order. This paper examines the theories proposed to explain centromere repositioning in mammals. These theories are interpreted in light of evidence gained in human studies and in our presented data from the marsupial model species Macropus eugenii, the tammar wallaby.

Animals↗
PubMed1997

[Early prognostic ultrasonographic indices in pregnancy with fetal cystic hygroma].

OBJECTIVE: Aim of this study was the correlation of same early ultrasonographic signs with fetal karyotype, prognosis of pregnancy and neonatal outcome. EXPERIMENTAL DESIGN: Volume of cystic hygroma and presence of septations are correlated with fetal karyotype and an ultrasonographic follow-up was carried out during pregnancy. Details concerning neonatal outcome were recorded at delivery. PATIENTS: Diagnosis was performed in 13 patients between 8.3 to 16.5 weeks' gestation referred to our center for prenatal diagnosis or for obstetric reasons. METHOD: Ultrasonographic examinations were performed using 5.0 and 6.0 MHz endovaginal convex probes. SURVEYS: Hygroma was diagnosed as a cystic dilatation in the nuchal region larger than 3 mm in diameter in the anterolateral aspects. The volume was calculated considering the lesion as spherical and using the standard formula for an ellipsoid volume; the presence of septations was considered. RESULTS: A volume greater than 70 cc3 and the presence of septations demonstrated a strictly correlation with fetal karyotype, evolution of the features, pregnancy and neonatal outcome. CONCLUSIONS: Prognosis varies depending on fetal karyotype, volume, presence of septations and other associated malformations. The volume of the hygroma and the presence of septa are associated with higher incidence of chromosomal diseases and a poorer fetal prognosis.

Female↗
PubMed1987

A highly repetitive DNA component common to all Cervidae: its organization and chromosomal distribution during evolution.

In recent work we have isolated and characterized a highly repetitive DNA (MMV satellite IA) from Muntiacus muntjak vaginalis, the species with the most reduced karyotype in the Cervidae family. We have now analysed the genomes of nine related species for the presence of MMV satellite IA components, and have determined their organization and chromosomal distribution. Repetitive satellite IA type DNA is present in all species of the Cervidae, and also in the bovine, but not in a species of the Tragulidae suggesting that these sequences were generated after the phylogenetic separation of Bovidae and Tragulidae. Studies on the organization of the satellite IA DNA in the various species revealed three main repeat lengths: 1400, 1000 and 807 bp. The relative proportion of satellite IA sequences present in any one of the three registers is strikingly different within the various species and can be correlated with the phylogeny of the Cervidae. The chromosomal locations of the satellite IA sequences were determined in seven species by in situ hybridization. It turned out that the chromosomal rearrangements leading to the reduction in the number of chromosomes during karyotype evolution have led to the elimination of satellite I DNA at most locations. In all tandem fusions, the satellite IA sequences located at the centromeres of the ancestral acrocentric chromosomes are lost. In contrast, during the centric fusion that generates the M. m. vaginalis X chromosome satellite IA sequences are amplified. Sequence motifs, which are known to be involved in recombinational events are present in the satellite IA and might have contributed to the unique karyotype variation in the Cervidae.

Animals↗
PubMed1997

Chromosomal evolution of the Chinese muntjac (Muntiacus reevesi).

The aim of this study was to test the validity of the hypothesis that the 2n=46 karyotype of the Chinese muntjac (Muntiacus reevesi) could have evolved through 12 tandem fusions from a 2n=70 hypothetical ancestral karyotype, which is still retained in Chinese water deer (Hydropotes inermis) and brown-brocket deer (Mazama gouazoubira). Combining fluorescence-activated chromosomal sorting and degenerate oligonucleotide-primed polymerase chain reaction, we generated chromosome-specific DNA paint probes for 13 M. gouazoubira chromosomes and most of the M. reevesi chromosomes with the exception of 18, 19 and X. These paint probes were used for fluorescence in situ hybridisation to chromosomal preparations of M. reevesi, H. inermis and M. gouazoubira. Chromosome-specific paint probes from M. reevesi chromosomes 1-5 and 11 each delineated more than one homologous pair (18 pairs in total) on the metaphases of H. inermis and M. gouazoubira. All the other probes from M. reevesi and probes from M. gouazoubira each hybridised to one pair of homologous chromosomes or regions. The C5 probe, derived from centromeric satellite sequences of M. reevesi, hybridised to the centromeric regions of all chromosomes of these three species. Most interestingly, several non-random interstitial signals, which are apparently localised to the putative fusion points, were found on chromosomes 1-5 and 11 of M. reevesi. Both the reciprocal painting patterns and localisation of the C5 probe demonstrate that M. reevesi chromosomes 1-5 and 11 could have evolved from 18 different ancestral chromosomes through 12 tandem fusions, thus providing direct molecular cytogenetic support for the tandem fusion hypothesis of karyotype evolution in M. reevesi.

Animals↗
PubMed1981

Cytogenetic follow-up of patients with nonlymphocytic leukemia. II. Acute nonlymphocytic leukemia.

Bone marrow (BM) karyotypes of 86 patients with acute nonlymphocytic leukemia (ANLL) were studied at the time of diagnosis: 39 of them (45%) were normally diploid and 47 (55%) showed acquired abnormalities. The median survival was no longer in the diploid group than in the aneuploid one. Nonrandom aberrations were often found: trisomy 8 (15 times), monosomy 7 (7 times), and t(8;21) (7 times). Two patients with acute promyelocytic leukemia presented with the t(15;17) in BM cells. Serial cytogenetic studies performed in 17 cases showed that karyotypic evolution closely followed the clinical evolution. Complete remission, obtained in 10 cases, was characterized by BM metaphases with a normal karyotype. Relapse after a period of complete remission was documented four times; the BM metaphases then showed the original abnormal karyotype with additional changes that, in three cases, were limited to a new structural aberration.

Acute Disease↗
PubMedDate not supplied

NOR activity, heterochromatin differentiation, and the Robertsonian polymorphism in Sus scrofa L.

The karyotype of the European wild pig (Sus scrofa scrofa L.) was analysed by means of silver-staining and the chromomycin A3/distamycin A/DAPI fluorescent banding technique to locate active NORs and to differentiate types of C-bands. The ribosomal RNA genes are localized at the secondary constrictions of chromosomes 8 and 10. All biarmed chromosomes, with the exception of chromosome 15/17 and the Y, had a chromomycin bright centromeric region that was moderately fluorescent with distamycin A/DAPI (DA/DAPI). Conversely, all acrocentric chromosomes and the Robertsonian fusion product (15/17) exhibited DA/DAPI bright centromeric heterochromatin. The results are compared with the chromosomal staining behavior of the domestic pig (Sus scrofa domestica L.) and discussed with respect to presumptive mechanisms of karyotypic evolution.

Animals↗
PubMed1977

[Chromosome complements of eleven bird species of the orders columbiformes, passeriformes and tinamiformes (author's transl)].

The chromosome complements of 11 species of birds from the Columbiformes, Passeriformes and Tinamiformes Orders are described. Their karyotypes' evolution are discussed and pericentric inversions, centric fissions and/or fusions seem to have been of great importance. Banding patterns in the several Orders will be of great importance to know better the mechanisms of chromosomal evolution.

Animals↗
PubMed1985

Genome evolution in pocket gophers (genus Thomomys). III. Fluorochrome-revealed heterochromatin heterogeneity.

Heterochromatin is a dominant component of the genome in the bottae group of the pocket gopher genus Thomomys, having had a major role in the karyotypic evolution of member species. Heterochromatin characteristics of two subspecies of T. bottae and one of T. umbrinus were examined with fluorochrome dyes identifying presumptive GC- and AT-rich regions. In two karyotype forms of T. b. fulvus and in T. umbrinus, chromatin that fluoresces brightly with chromomycin A3 is also C-band positive, although not all heterochromatin fluoresces. However, in T. b. bottae, only euchromatic regions fluoresce brightly with chromomycin. Fluorescence patterns produced with DAPI are the reverse of the chromomycin banding in all karyotypic forms. Heterochromatin in these taxa is thus highly differentiated, exhibiting heterogeneity in staining characteristics, and presumably in underlying DNA sequences, both across the genome within a given chromosomal complement as well as among the different karyotypic races and species of the bottae group of pocket gophers.

Animals↗
PubMed2026

Unraveling evolutionary relationships in the Sida generic alliance (Malvaceae, Malvoideae): a phylogenetic and cytotaxonomic overview.

Sida (Malvaceae), the largest Malveae-Abutilinae member, has poorly defined morphological limits which overlaps with 11 phylogenetically closely related genera that comprises the "Sida generic alliance". The 12 genera are distributed in the tropics especially in Brazil where one third of its species diversity is found. Evolutionary relationships within Sida generic alliance remain unresolved due to morphological convergence, limited taxon sampling, and lack of integrative approaches including cytogenetic data. We reconstructed the phylogeny of Sida and allied genera using a multilocus dataset (nuclear ITS and seven plastid loci) including 193 species classified in 19 genera and analyzed chromosome evolution using cytogenetic data (chromosome number) for 79 species of the 19 genera. The phylogeny recovered seven clades-Abutilon, Bakeridesia, Callianthe, Gaya, and three Sida clades (I-III)-and confirmed the polyphyly of Sida, the largest genera. We detected reticulate evolution, with incongruence between nuclear and plastid topologies. Chromosome number ranged from 2n = 12 to 60 and represented synapomorphies for most clades. Ancestral character reconstruction indicated that ascending dysploidy and polyploidy predominated in karyotype evolution of Sida and allied genera. Our results reveal taxonomic incongruence in current classifications probably related to reticulate evolution. A generic-level taxonomic revision is necessary and should rely on integrated phylogenetic and karyotypic evidence. This study provides a framework for phylogenetic systematics and emphasizes the role of Brazil as a hotspot for plant genomic research.

Phylogeny↗
PubMed1976

Translocations of acrocentric chromosomes and their implications in the evolution of sheep (Ovis).

Cytogenetic evidence suggests that the caprids (sheep and goats) evolved from a common ancestor with a 2n=60 karyotype. Although goats (Capra) retained the primitive 2n=60 karyotype, sheep (Ovis) underwent a sequential reduction in the number of chromosomes by means of acrocentric translocation. The formation of the first metacentric autosome (M1) occurred in the aoudad (Ammotragus) and urial (O. vignei), resulting in a 2n=58 karyotype. The G-bands are homologous, which implies both genotypes arose from a common ancestor, possibly a rupicaprid. Based on G-bands, acrocentric chromosomes 1 and 7 of the 2n=60 karyotype formed the M1. The X chromosome, which is the second longest acrocentric in the 2n=60 karyotype, became the longest acrocentric in Ammotragus and Ovis (2n=58). The second pair of metacentrics to evolve, which is ranked in the M3 position of the 2n=54 karotype, resulted from the translocations of acrocentric chromosomes 4 and 14 or 15 in the 2n=60 karyotype. The M2 was the third pair of metacentrics to be formed and resulted from the translocations of acrocentric chromosomes 3 and 12 or 13 in the 2n=60 karyotype. The G-bands of all 2n=54 karyotypes are homologous, which indicates origin from a common ancestor. Evidence is presented that suggests a prezygotic selection is bringing about a reduction in diploid chromosome numbers. The possible roles of fission and fusion in the karyotypic evolution of Ovis are discussed.

Animals↗
PubMed1992

Benign mixed tumor of canine mammary gland showing an r(X) and trisomy 5 as the only clonal abnormalities.

We report a benign mixed tumor of the canine mammary gland which showed an r(X) and trisomy 5 as the only clonal karyotypic deviations. Clonal aberrations were observed in 79 of 160 of the metaphases. Of these, 48 cells had both the r(X) and trisomy 5, whereas the remaining metaphases were characterized by the r(X) as the only clonal aberration. We conclude that formation of the ring chromosome was the first abnormality, followed by trisomy 5 during the course of karyotypic evolution.

Animals↗
PubMed2004

The evolution of a neo-XY1Y2 sex chromosome system by autosome-sex chromosome fusion in Dundocoris nodulicarinus Jacobs (Heteroptera: Aradidae: Carventinae).

Sibling subspecies of Dundocoris nodulicarinus, inhabiting different isolated indigenous evergreen forests in South Africa, have chromosome numbers of 2n(male) = 14XY, 9XY1Y2 and 7XY1Y2. The ancestral chromosome number of Dundocoris is probably 2n(male) = 28XY and several chromosome fusions were involved in the karyotype evolution of these taxa. The XY1Y2 sex chromosome system of the 9XY1Y2 D. nodulicarinus novenus originated by the fusion of a large autosome with the X-chromosome, forming a neo-X with the homologue of the fused autosome forming the neo-Y (=Y1) and the original Y-chromosome, the Y2. While the original X- and Y-chromosomes are heterochromatic and heteropycnotic during prophase I, the autosomal part of the neo-X and the neo-Y stay euchromatic and behave like a normal autosomal pair, forming synapsis and chiasmata. The XY1Y2 sex chromosome system of the 7XY1Y2 D. nodulicarinus septeni probably originated from the 9XY1Y2 karyotype when the homologous chromosomes of a small autosomal pair fused with the original X- and Y-chromosomes, respectively. In both the subspecies with the neo-XY1Y2 systems, the original sex chromosomes still undergo chromatid segregation at anaphase I (= post-reductional). The evolution and behaviour of the karyotypes and sex chromosome systems during the course of meiosis in the subspecies of D. nodulicarinus are described, discussed and illustrated.

Animals↗
PubMed1990

The Spalacidae: evolutionary history, speciation and population biology.

The evolutionary history of Spalacidae is reviewed taxonomically, paleontologically and neontologically. We focused selectively on taxonomy, biogeography, paleontology and evolutionary origins, chromosomal evolution, population biology and the species concept in Spalacidae. We concluded that the taxonomy of Spalacidae needs a modern revision based on chromosome and molecular-genetic data, beside that of morphology, physiology and behavior. The subterranean Spalacidae originated probably from a muroid-cricetoid stock in Asia Minor or vicinity, in Upper Oligocene times and adaptively radiated underground in the Balkans, steppic Russia and Middle East, extending into North Africa. The major important evolutionary feature in peripatric or allopatric speciation and adaptive radiation was karyotypic evolution, primarily through Robertsonian changes. More than 30 karyotypes (2n = 38-62; NF = 72-124) earlier represented by 8 classical species, occur primarily allopatrically or parapatrically, with only marginal sympatry, across the Eastern Mediterranean range of the family. Most karyotypes represent biospecies adapted at multiple organizational levels to their different ecologies. A short overview is presented on population biology and life history parameters of the Spalacidae which result in K-selected, "equilibrium species". Speciation in action and adaptive radiation embracing molecular and organismal adptations to the subterranean unique ecotope and to four different climatic regimes, have been multidisciplinarily studied in the Israeli Spalax ehrenbergi superspecies.

Animals↗