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PubMed2005

[Genomic structure of the autotetraploid oat species Avena macrostachya inferred from comparative analysis of the ITS1 and ITS2 sequences: on the oat karyotype evolution during the early stages of the Avena species divergence].

To examine the genomic structure of Avena macrostachya, internal transcribed spacers, ITS1 and ITS2, as well as nuclear 5.8S tRNA genes from three oat species with AsAs karyotype (A. wiestii, A. hirtula, and A. atlantica), and those from A. longiglumis (AlAl), A. canariensis (AcAc), A. ventricosa (CvCv), A. pilosa, and A. clauda (CpCp) were sequenced. All species of the genus Avena examined represented a monophyletic group (bootstrap index = 98), within which two branches, i.e., species with A- and C-genomes, were distinguished (bootstrap indices = 100). The subject of our study, A. macrostachya, albeit belonging to the phylogenetic branch of C-genome oat species (karyotype with submetacentic and subacrocentric chromosomes), has preserved an isobrachyal karyotype, (i.e., that containing metacentric chromosomes), probably typical of the common Avena ancestor. It was suggested to classify the A. macrostachya genome as a specific form of C-genome, Cm-genome. Among the species from other genera studied, Arrhenatherum elatius was found to be the closest to Avena in ITS1 and ITS structure. Phylogenetic relationships between Avena and Helictotrichon remain intriguingly uncertain. The HPR389153 sequence from H. pratense genome was closest to the ITS1 sequences specific to the Avena A-genomes (p-distance = 0.0237), while the differences of this sequence from the ITS1 of A. macrostachya reached 0.1221. On the other hand, HAD389117 from H. adsurgens was close to the ITS1 specific to Avena C-genomes (p-distance = 0.0189), while its differences from the A-genome specific ITS1 sequences reached 0.1221. It seems likely that the appearance of highly polyploid (2n = 12-21x) species of H. pratense and H. adsurgens could be associated with interspecific hybridization involving Mediterranean oat species carrying A- and C-genomes. A hypothesis on the pathways of Avena chromosomes evolution during the early stages the oat species divergence is proposed.

Avena↗
PubMed2004

Phylogeny and karyotype evolution of the Iberian Leptynia attenuata species complex (Insecta Phasmatodea).

An in-depth analysis of the Leptynia attenuata species complex has been performed by cytochrome oxidase subunit 2 (cox2) gene sequencing as well as karyotype and allozyme analysis. The whole set of data allows to largely resolve the taxonomy of the group and suggests an overall trend of chromosomal repatternings through a progressive reduction of the chromosome number. A previously suggested new species has been also confirmed on a genetic basis. Data are discussed in order to depict a phylogenetic and phylogeographic scenario fitting the observed genetic relationships between the different species of the group. Chromosome rearrangements are proposed as the major speciation driving force within the group and androgenetic reproduction is suggested as a shortcut to overcome the problem of fixing chromosomal rearrangements that are strongly underdominant in heterozygotes.

Animals↗
PubMed1981

Karyotype evolution and sex chromosome differentiation in Schistosomes (Trematoda, Schistosomatidae).

The morphology of C-banded metaphase chromosomes has been studied in two hermaphroditic and ten gonochoristic digenetic trematodes (schistosomes). Comparison of numbers and morphology of chromosomes indicates that the karyotype of primitive trematodes probably was composed of 10 (or 11) pairs of telocentric or subtelocentric chromosomes, and reduction of chromosome numbers in advanced species resulted from centromeric fusion rather than elimination of chromosomes. Observation of heteromorphic chromosomes in a hermaphroditic trematode (Spirorchis) suggested a differentiation of "pre-sex" chromosomes in species ancestral to dioecious trematodes which possess distinctly differentiated sex chromosomes. Our results indicate that differentiation of Z and W chromosomes in the gonochoristic trematodes resulted from: (a) partial constitutive heterochromatinization of the W chromosome (Schistosoma mansoni and S. haematobium complexes, African schistosomes), (b) deletion of part of the W (S. japonicum and S. mekongi, Asian schistosomes), and (c) translocation of part of one sex chromosome onto another (Schistosomatium douthitti and Heterobilharzia americana, American schistosomes) with subsequent heterochromatinization of the W in H. americana.

Animals↗
PubMed1986

Karyotypic evolution in human malignant melanoma.

Chromosome studies were performed on direct preparations, early passage cultures, and cell lines derived from melanocytic lesions of 37 patients. There were six congenital or common acquired nevi, six dysplastic nevi, one early primary melanoma (radial growth phase), three complex melanomas (RGP with foci of vertical growth phase), six advanced primary melanomas (VGP), and 26 metastases. The karyotype was normal in the six common nevi. A chromosomally abnormal clone with a single karyotypic alteration was found in two dysplastic nevi. All melanomas had clones with multiple cytogenetic changes. Nonrandom abnormalities involving translocations or deletions in the short arm of chromosome #1, either arm of chromosome #6, and/or extra copies of the short arm of chromosome #7 were present in all melanomas. These were not obviously associated with a particular stage of disease, except that the only nonrandom alteration in the early (RGP) melanoma involved chromosome #6. In four cases, cytogenetic data were available on both a primary melanoma and its metastases. In each instance there were common alterations (demonstrating the clonality of the disease), as well as additional changes in the metastases. Our findings indicate that demonstrable somatic genetic abnormalities increase in severity with clinical progression of melanocytic disease, but additional data are required to establish the significance of specific karyotypic changes (and the involved genes) in the clinical evolution of these disorders.

Chromosome Aberrations↗
PubMed2005

Reinforcement of pre-zygotic isolation and karyotype evolution in Agrodiaetus butterflies.

The reinforcement model of evolution argues that natural selection enhances pre-zygotic isolation between divergent populations or species by selecting against unfit hybrids or costly interspecific matings. Reinforcement is distinguished from other models that consider the formation of reproductive isolation to be a by-product of divergent evolution. Although theory has shown that reinforcement is a possible mechanism that can lead to speciation, empirical evidence has been sufficiently scarce to raise doubts about the importance of reinforcement in nature. Agrodiaetus butterflies (Lepidoptera: Lycaenidae) exhibit unusual variability in chromosome number. Whereas their genitalia and other morphological characteristics are largely uniform, different species vary considerably in male wing colour, and provide a model system to study the role of reinforcement in speciation. Using comparative phylogenetic methods, we show that the sympatric distribution of 15 relatively young sister taxa of Agrodiaetus strongly correlates with differences in male wing colour, and that this pattern is most likely the result of reinforcement. We find little evidence supporting sympatric speciation: rather, in Agrodiaetus, karyotypic changes accumulate gradually in allopatry, prompting reinforcement when karyotypically divergent races come into contact.

Animals↗
PubMed2005

Karyotypic evolution of a novel cervid satellite DNA family isolated by microdissection from the Indian muntjac Y-chromosome.

A minilibrary was constructed from DOP-PCR products using microdissected Y-chromosomes of Indian muntjac as DNA templates. Two microclones designated as IM-Y4-52 and IM-Y5-7 were obtained from negative screening of all three cervid satellite DNAs (satellites I, II, and IV). These two microclones were 295 and 382 bp in size, respectively, and shared approximately 70% sequence homology. Southern blot analysis showed that the IM-Y4-52 clone was repetitive in nature with an approximately 0.32-kb register in HaeIII digest. Sequence comparison revealed no similarities to DNA sequences deposited in the GenBank database, suggesting that the microclone sequences were from a novel satellite DNA family designated as cervid satellite V. A subclone of an Indian muntjac BAC clone which screened positive for IM-Y4-52 had a 3,325-bp insert containing six intact monomers, four deleted monomers, and two partial monomers. The consensus sequence of the monomer was 328 bp in length and shared more than 80% sequence homology with every intact monomer. A zoo blot study using IM-Y4-52 as a probe showed that the strong hybridization with EcoRI digested male genomic DNA of Indian muntjac, Formosan muntjac, Chinese muntjac, sambar deer, and Chinese water deer. Female genomic DNA of Indian muntjac, Chinese water deer, and Formosan muntjac also showed positive hybridization patterns. Satellite V was found to specifically localize to the Y heterochromatin region of the muntjacs, sambar deer, and Chinese water deer and to chromosome 3 of Indian muntjac and the X-chromosome of Chinese water deer.

Animals↗
PubMed2005

Heterochromatin differentiation shows the pathways of karyotypic evolution in Israeli mole rats (Spalax, Spalacidae, Rodentia).

C-banding, base-specific fluorochrome staining (CMA3/DA/DAPI), and comparative genomic hybridization (CGH) were used to analyze the constitutive heterochromatin in two Israeli Spalax species, S. galili (2n = 52) and S. judai (2n = 60). It was shown that C-positive centromeric heterochromatin and some telomeric sites comprise GC-rich DNA sequences in both species. Comparative genomic in situ hybridization revealed slight qualitative differences in highly repetitive sequences in the two Spalax species. Eight acrocentric pairs in S. judai that are involved in Robertsonian rearrangements, possessed composite heterochromatin with a preference of S. judai highly repetitive sequences in the proximal region. Heterochromatin of the sex chromosomes, two biarmed homologous pairs (4 and 5) in both species, and acrocentric chromosomes from the group with a variable centromere position in S. judai was entirely species-specific. The high level of homology in the composition of heterochromatin may relate to the recent divergence of Israeli Spalax. Interspecies heterochromatin differences are discussed in the context of possible mechanisms in the Spalax chromosome evolution.

Animals↗
PubMed1987

Karyotypic evolution in a B-cell lymphoma.

A B-cell lymphoma in the lung of a 59-year-old woman showed a near-pentaploid karyotype and chromosomal changes indicating a t(8;14) in cells from a pleural aspirate. Cells from metastases to the skin and a second pleural aspirate were pseudodiploid, but showed separate further complex cytogenetic changes. Among these was a 14q+ chromosome, but the #8 chromosomes apparently were normal. It is suggested that there was a loss of the derivative 8q- chromosome from the t(8;14) followed by homozygozity of the normal #8 chromosome.

Aged↗
PubMed1992

Karyotype evolution in a patient with biphenotypic neonatal leukemia.

We present the case of a 4-day-old boy with acute lymphoblastic leukemia showing at onset a karyotype 46,XY,t(4;11)(q21;q23). At relapse an additional change, add(2), was present. Molecular analysis showed the same immunoglobulin rearrangement both at onset and at relapse, but immunohistochemical analysis revealed some cells having myeloid features. A continuous cell line derived from the leukemic blasts of the patient presented typical monoblastic features.

Cell Line↗
PubMed1984

Sequential karyotypic evolutions and bone marrow aplasia preceding acute myelomonocytic transformation from myelodysplastic syndrome.

Serial haematopathological and cytogenetic studies disclosed three distinct clinical phase in a case of refractory anaemia (RA), a subtype of myelodysplastic syndrome (MDS; FAB group, 1982): first, chronic MDS phase (1 year 10 months) with karyotypic abnormality (45, XY, --7) (Clone I); second, hypo-aplastic phase concurrent with first clonal evolution (45, XY, --7, 12p--) (Clone II); third, acute myelomonocytic leukaemia phase (6 months) with second clonal evolution (45, XY, --7,t (1q --; Bq+), Bq --, 12p --) (Clone III). In the second phase the bone marrow became almost aplastic as Clone II expanded progressively, indicating simultaneous occurrence in Clone II stem cells of growth advantage for self-renewal function over Clone I and normal stem cells, and arrest of differentiation. These observations support the hypothesis that leukaemic change in MDS, at least in RA, occurs by stepwise clonal evolution(s), not by progressive arrest of differentiation in original MDS clone.

Anemia, Aplastic↗
PubMed1988

Chromosome abnormalities and karyotypic evolution in 83 patients with myelodysplastic syndrome and predictive value for prognosis.

In a chromosome study of 83 patients with myelodysplastic syndrome (MDS), 50 showed a clonally abnormal karyotype. The most frequent abnormalities were the whole or a partial loss of the long arm of chromosome 7 (-7 or 7q-) (14 patients) and a partial loss of the long arm of chromosome 5 (5q-) (11 patients). Twenty patients with 5q- and/or -7 or 7q- had a shorter survival (median, 5 months) than those with other abnormal karyotypes (22 months) or those with a normal karyotype (28 months). In this series 30 patients were examined cytogenetically on two or more occasions during the course of their illness. Ten patients showed a further karyotypic alteration from the initial findings, and, concomitantly, their disease progressed in severity including overt leukemia. These patients had a shorter survival (median, 2 months) after the chromosome reanalysis than the other 20 patients who did not have further karyotypic changes (21 months). Thus, the prognosis of patients with MDS can be predicted more accurately by reanalyzing the chromosomes after the initial analysis.

Adult↗
PubMed1998

Amplification of telomeric DNA and the extent of karyotypic evolution.

The distribution of telomeric DNA in the genomes of the antelope ground squirrel, Ammospermophilus harrisii (family Sciuridae; 2n = 32) and the African black-footed cat, Felis nigripes (family Felidae; 2n = 38) were compared by fluorescence in situ hybridization (FISH) technique. These two mammalian species have the highest and the lowest amount of C-banded regions, respectively. FISH preparations with the human telomeric DNA probe showed that all C-banded segments in the A. harrisii chromosomes, except a few intercalary segments, were hybridizing with this DNA. F. nigripes showed hybridization only on the termini of each chromosome, and the C-banded regions did not hybridize with telomeric DNA on FISH analysis. The C-banded chromosomal arms in another rodent species, Peromyscus eremicus (family Cricetidae; 2n = 48), when hybridized with human telomeric DNA showed signals only in the termini of chromosomes but not in the heterochromatic arms. These observations indicate that not all C-banded regions in rodent species are telomeric DNA. The amplification of telomeric DNA in relation to speciation is discussed.

Animals↗
PubMed1999

Retention of polysomy at 9p23-24 during karyotypic evolution in human breast cancer cell line COLO 824.

Somatic genetic alterations of 9p have been seen in a wide range of human cancers, including breast cancer. Loss of heterozygosity analysis of primary breast cancer tumors has revealed a high frequency of deletion of DNA from 9p21-22 encompassing the MTSI (P16/CDKN2A) gene. We report the approximately tenfold increase in copy number of DNA from 9p23-24, which is far distal to P16/CDKN2A in female breast cancer cell line COLO 824, as revealed by fluorescence in situ hybridization, comparative genomic hybridization, and microsatellite analysis. Amplification of DNA has been reported previously to encompass multiple sites of the genome of the breast cancer cell, but increase in DNA copy number has not been seen in distal 9p.

Aneuploidy↗
PubMed1993

Chromosome banding in Amphibia. XVIII. Karyotype evolution and genomic size variation in Pleurodema (Anura, Leptodactylidae).

DNA flow cytophotometric measurements demonstrate that the quantity of nuclear DNA of the South American leptodactylid frog Pleurodema brachyops is 3.4 times greater than that of P. thaul. Nevertheless, the conventionally stained karyotypes of both species are nearly identical. In the metaphase chromosomes of P. brachyops, the chromatin has a distinctly higher degree of packaging than in those of P. thaul. C-banding reveals that almost 6 times the constitutive heterochromatin is present in the karyotype of P. brachyops than in the karyotype of P. thaul. Analysis of fluorescence banding patterns shows that the chromosomes of P. brachyops contain AT- and GC-rich heterochromatin, whereas the karyotype of P. thaul is devoid of brightly fluorescing heterochromatin. The substantial differences in the genome sizes of Pleurodema is explained by homogeneous, symmetrical changes in the amounts of all DNA sequence classes along all chromosomes, which preserved the ancestral morphology of the chromosomes.

Animals↗