Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “karyotype evolution”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,621 records · Page 90Linked to original sources
PubMed1986

The 724 family of DNA sequences is interspersed about the pericentromeric regions of human acrocentric chromosomes.

We describe the organization of the complex, interspersed 724 family of DNA sequences that is distributed in multiple copies about the pericentromeric region of human acrocentric chromosomes. 724 family members were isolated using an efficient recombination-based assay for nucleotide sequence homology to screen a human genomic library. Eight related but distinct 724 family members were isolated that hybridized to a total of 20 different human-genomic EcoRI DNA fragments spanning 100,000 base pairs. In contrast with tandemly clustered satellite and ribosomal DNA sequences also located on the short arms of human acrocentric chromosomes, 724 family members are interspersed. No evidence for local interspersion or homology between 724 family members and ribosomal or satellite DNA sequences was found. Juxtaposition of the complex 724 family to the nucleolus organizer region was a recent event in primate evolution. The unique organization of 724 family members on each of the five human acrocentric chromosomes indicates that the 724 family continues to evolve within the human karyotype.

Base Composition↗
PubMed2001

Genetic heterogeneity and clonal evolution in neuroblastoma.

Tumour heterogeneity and clonal evolution at the genetic level may explain the development of malignant or resistant disease during clinical progression of neuroblastoma (NB). In this report we use 1p allelic analysis and DNA ploidy to evaluate clonal heterogeneity and clonal selection in vivo. We studied a total of 69 tumours from 29 patients with NB. To evaluate tumour heterogeneity and clonal evolution in vivo we used a panel of polymorphic allelic markers mapping to chromosome 1. 33 tumours from 12 patients (group 1) were obtained from different sites during the same surgery or at sequential surgeries without intervening chemotherapy to evaluate genetic heterogeneity. Paired samples from 10 patients (group 2) were used to evaluate clonal selection before and after chemotherapy. In 6 cases paired tumours and derived cell lines were studied. Analysis of DNA ploidy changes by karyotype, FISH and flow cytometry was performed in 15 tumours from 6 multiply recurred local-regional (LR) NB patients. Allelotype study revealed that 66% (8/12) of group 1 samples were heterogeneous, with distinct allelic patterns in tumour samples separated by time or location. In group 2 allelic patterns were different in post-chemotherapy specimens in 60% (6/10). DNA ploidy analysis showed that pre-chemotherapy samples contained 2 distinct ploidy clones, one diploid and one triploid, whereas all post-chemotherapy tumor samples were 100% diploid. These findings suggest that NB exhibits a high degree of clonal heterogeneity and clonal evolution occurs during the course of therapy and clinical progression.

Chromosomes, Human, Pair 1↗
PubMed1997

Unusual clonal chromosomal evolution in a breast carcinoma and its lymph node metastasis in a patient with Down syndrome.

A cytogenetic study was performed on a primary breast carcinoma and its axillary lymph node metastasis from a 53-year-old patient with trisomy 21, a carrier of a constitutional der(21;21). A translocation t(X;21) and the loss of the other X chromosome were shared by all karyotypes from tumor cells. The primary tumor was hyperdiploid with several gains of whole chromosomes. In contrast, most cells from the metastasis shared several rearrangements and losses leading to a hypodiploid karyotype. No normal chromosome 17 was present; instead, an i(17)(q10) and a fragment, detected by chromosome painting and presumably corresponding to a rearranged 17p, were found. Immunostaining for p53 was strongly positive in the metastasis but not in the primary tumor, suggesting a mutation of the TP53 gene in the metastasis. Finally, a small cell population of the metastasis was hyperdiploid like the clone in the primary tumor, suggesting that the node was colonized twice, at an early stage and a later stage of the clonal evolution of the tumor.

Axilla↗
PubMed1986

Spontaneous in vitro neoplastic evolution: recurrent chromosome changes of newly immortalized Chinese hamster cells.

Spontaneous neoplastic progression in cultured Chinese hamster cells was studied at the earliest stage possible. Eighteen independent newly immortalized cell populations (from six individual Chinese hamsters) were characterized for karyotype instability. Colonies were selected from initial sparse platings of adult or fetal cells and were expanded for study. The chromosomes from these newly established cell lines were studied using a combination of G-banding and flow karyotype analysis. At a slightly later passage, the 18 cell lines were tested for tumorigenicity in nude mice. Frequent recurring chromosome changes were observed in the karyotypes. The most frequent changes were either total or partial trisomy of chromosome #3 (83%) and trisomy of chromosome #5 (61%). Only 4 of 18 clones (22%) were tumorigenic at the time of testing, and these had long latent periods. The presence of recurrent chromosome changes did not obligate these cell lines to become tumorigenic, but the karyotype instability appeared to be an indicator of the ongoing process of neoplasia.

Animals↗
PubMed2005

Ductal breast carcinoma develops through different patterns of chromosomal evolution.

In a previous study that used comparative genomic hybridization (CGH) to analyze 43 ductal breast carcinomas selected for hyperdiploidy, we proposed the existence of two distinct pathways of chromosomal evolution. In the present study, in which we reassessed our cytogenetic findings on 158 ductal breast carcinomas selected for having a modal number of chromosomes of fewer than 60, we confirmed the existence of two subtypes of tumors. Along with the great majority of tumors (142 of 158) that evolved through structural rearrangements with no or very few whole-chromosome gains, we found that a minor subset (16 of 158) evolved through progressive gains of whole chromosomes with no or only a few associated rearrangements. In this article, we describe the karyotypes of these 16 tumors together with data from CGH, which was performed for 10 of them. Chromosomes 5, 7, 8, and 20 were the most frequently gained. Our findings support the evidence of a new pathway of chromosomal evolution in a small subset of ductal breast carcinomas characterized by numerical chromosome aberrations.

Aged↗
PubMed1994

Secondary chromosomal abnormalities in acute leukemias.

Secondary chromosomal aberrations reported in the literature were surveyed in acute myeloid or lymphoblastic leukemia (AML or ALL) with one of the following primary abnormalities: in AML, t(1;3), t(1;22), der(1;7), inv(3), t(3;5) +4, del(5q), t(6;9), -7, t(7;11), del(7q), +8, t(8;16), t(8;21), +9, t(9;11), del(9q), t(9;22), +11, del(11q), t(11;19), del(12p), +13, t(15;17), inv(16), t(16;21), i(17)(q10), del(20q), -21, +21, +22, and -Y; in ALL, t(1;14), t(1;19), der(19)t(1;19), t(4;11), del(6q), t(8;14)(q24;q11), t(8;14)(q24;q32), t(8;22), del(9p), dic(9;12), i(9)(q10), t(9;22), t(10;14), t(11;14), t(11;19), del(12p), -20, +21, and del(22q). Out of 7111 acute leukemias with clonal karyotypic aberrations, 2414 AMLs and 1078 ALLs had one of the selected primary chromosome rearrangements, and 40 and 49% of these AMLs and ALLs, respectively, displayed additional abnormalities. The type and frequency of these secondary changes were ascertained and then correlated with both the primary abnormality and the morphology or immunophenotype of the acute leukemia. The distribution of the secondary changes was clearly nonrandom. The most frequent numerical changes were -Y, -X, -7, +8, and +22 in AML and +X, +6, -7, +8, and +21 in ALL. The most common structural aberrations were del(5q), del(7q), and del(9q) in AML and dup(1q), i(7q)(q10), and der(22)t(9;22) in ALL. Some secondary changes were common to both disease groups, e.g. -7, +8, and +21, but several anomalies were restricted to either AML, such as -X, -5, and del(9q), or ALL, e.g. +X, i(7)(q10), and i(9)(q10). The type and frequency of the secondary aberrations varied within the AMLs and ALLs, not only among the different primary abnormality subgroups but also among the AML morphologies and the immunophenotypic maturation degrees of the ALLs. In general, the type of primary abnormality, rather than the differentiation stage of the acute leukemia, appeared to be instrumental in determining the type of secondary changes accruing. This conclusion was based on the finding that several primary abnormalities characterizing acute leukemias of the same morphology or immunophenotype displayed different patterns of secondary anomalies. The nonrandom, and sometimes quite specific, patterns of secondary aberrations strongly indicate that they are responsible for important phenotypic features of the tumor cell population, presumably closely associated with tumor progression. The molecular pathogenetic consequences of the secondary anomalies are unknown, but since most secondary changes are monosomies, trisomies, deletions, or isochromosomes resulting in genomic imbalances, one may hypothesize that gene dosage alterations rather than specific gene rearrangements are essential for tumor evolution.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗
PubMed2000

Interstitial deletion of the short arm of chromosome 12 during clonal evolution in myelodysplastic syndrome with t(5;12)(q13;p13) involving the ETV6 gene.

We report here a 65-year-old man with a myelodysplastic syndrome (MDS), refractory anemia with excess of blasts. He had received chemotherapy with tegafur for renal carcinoma. Chromosome analysis of bone marrow cells revealed complex karyotypes; del(5)(q13) was observed in all 20 metaphase spreads, and two related aberrations, add(12)(p11) and add(12)(p13), were detected in 13 and 7 cells, respectively. Fluorescence in situ hybridization (FISH) analysis with chromosome-specific DNAs revealed that these alterations originated from a reciprocal translocation (5;12)(q13;p13). Therefore, del(5)(q13), add(12)(p11), and add(12)(p13) were revised as der(5)t(5;12)(q13;p13), der(12)del(12)(p11p13)t(5;12)(q13;p13), and der(12)t(5;12)(q13;p13), respectively. Fluorescence in situ hybridization with a series of cosmid probes spanning the ETV6 gene showed that the 12p13 breakpoint on the der(12)t(5;12)(q13;p13) was located in intron 1, but the exon 1 signal was deleted. Our results suggest that a fusion gene was generated between the 5'-end of an unidentified partner at 5q13 and the 3'-end of ETV6 by t(5;12)(q13;p13), and that the interstitial deletion (12)(p11p13) occurred following t(5;12) during clonal evolution. del(12)(p11p13), including the rearranged ETV6 gene, may be implicated in the progression of MDS.

Aged↗
PubMed2005

Systematics and evolution of the subfamily Gerbillinae (Mammalia, Rodentia, Muridae).

Although they represent a quarter of the mammalian species, the evolutionary relationships among as well as within, the main murid lineages are still controversial. The subfamily Gerbillinae is no exception as previous studies based on morphological, karyotypical, and allozyme characters are highly incongruent. Here, we present the first molecular phylogeny for gerbils based on cytochrome b and 12S rRNA mitochondrial genes. Results are largely congruent between the two genes as well as with the concatenated data set with most of the nodes being well-supported. Based on the topologies retrieved here, we (1) propose the identification of three main clades, (2) support the split of Tatera genus into an Asian and an African group, the latter including Gerbillurus species, and (3) provide some evidence towards the inaccuracy of subgeneric divisions within both Gerbillus and Meriones. In addition, the sharp contrast between the genetic characters and morphological data sets suggest high levels of convergence, probably as a result of strong environmental constraints imposed on these rodents adapted to arid and semi-arid regions. Finally, molecular datings for the various cladogenetic events are in good agreement with the known gerbilline fossil record and support an African origin with subsequent migrations to Asia.

Africa↗
PubMed1997

Radiation and speciation of spider monkeys, genus Ateles, from the cytogenetic viewpoint.

The chromosomes of 22 animals of four subspecies of the genes Ateles (A. paniscus paniscus, A. p. chamek, A. belzebuth hybridus, and A. b. marginatus) were compared using G/C banding and NOR (nucleolar organizer region) staining methods. The cytogenetic data of Ateles in the literature were also used to clarify the phylogenetic relationships of the species and subspecies and to infer the routes of radiation and speciation of these taxa. Chromosomes 6 and 7 that showed more informative geographic variation and the apomorphic form 4/12, exclusively in A. p. paniscus, are the keys for understanding the evolution, radiation, and specification of the Ateles taxa. The ancestral populations of the genus originated in the southwestern Amazon Basin (the occurrence area of A. paniscus chamek) and spread in the Amazon Basin and westward, crossing the Andes and colonizing Central America and northwesternmost regions of South America. The evolutionary history of the northern South American taxa is interpreted using the model of biogeographical evolution postulated by Haffer [Science 185:131-137, 1969]. Ateles paniscus paniscus is the genetically most differentiated form and probably derives from A. belzebuth hybridus. Based on the karyotype differences, the populations of Ateles can be divided into four different groups. These findings indicate the necessity of a more coherent taxonomic arrangement for the taxa of Ateles.

Animals↗
PubMed1999

Divergent human Y-chromosome microsatellite evolution rates.

In this work, we analyze several characteristics influencing the low variability of the microsatellite DYS19 in the major founder Amerindian Y chromosome lineage containing the point mutation DYS199-T. Variation of DYS19 was compared with that of five other Y-linked tetranucleotide repeat loci (DYS389A, DYS389B, DYS390, DYS391, and DYS393) in the DYS199-T lineage. All the other microsatellites showed significantly higher levels of variability than DYS19 as measured by gene diversity and repeat number variance. Moreover, we had previously shown that DYS19 had high diversity in Brazilians and in several other populations worldwide. Thus, the slow DYS19 evolution in the DYS199-T lineage seems to be both locus and allele specific. To understand the slow DYS19 evolutionary rate, the microsatellite loci were compared according to their mapping on the Y chromosome and also on the basis of structural aspects such as the base composition of the repeat motif and flanking regions and the degree of perfection and size (repeat number) of the variable blocks. The only observed difference that might be related to the low DYS19 variability is its small average number of repeats, a value expected to be closer to the founder DYS19 allele in the DYS199-T lineage. These data were also compared to other derived Y lineages. The Tat-C lineage displayed a lower DYS19 variability correlated to a small average repeat number, while in the DYS234-G lineage, a high DYS19 variability was found associated to a larger average repeat number. This approach reveals that evolution of Y microsatellites in lineages defined by slowly evolving markers, such as point mutations, can be greatly influenced by the size (number of repeats of the variable block) of the founder allele in each microsatellite locus. Thus lineage-dating methods using microsatellite variation should be practiced with great care.

Base Sequence↗
PubMed2006

Evidence for different origin of sex chromosomes in snakes, birds, and mammals and step-wise differentiation of snake sex chromosomes.

All snake species exhibit genetic sex determination with the ZZ/ZW type of sex chromosomes. To investigate the origin and evolution of snake sex chromosomes, we constructed, by FISH, a cytogenetic map of the Japanese four-striped rat snake (Elaphe quadrivirgata) with 109 cDNA clones. Eleven of the 109 clones were localized to the Z chromosome. All human and chicken homologues of the snake Z-linked genes were located on autosomes, suggesting that the sex chromosomes of snakes, mammals, and birds were all derived from different autosomal pairs of the common ancestor. We mapped the 11 Z-linked genes of E. quadrivirgata to chromosomes of two other species, the Burmese python (Python molurus bivittatus) and the habu (Trimeresurus flavoviridis), to investigate the process of W chromosome differentiation. All and 3 of the 11 clones were localized to both the Z and W chromosomes in P. molurus and E. quadrivirgata, respectively, whereas no cDNA clones were mapped to the W chromosome in T. flavoviridis. Comparative mapping revealed that the sex chromosomes are only slightly differentiated in P. molurus, whereas they are fully differentiated in T. flavoviridis, and E. quadrivirgata is at a transitional stage of sex-chromosome differentiation. The differentiation of sex chromosomes was probably initiated from the distal region on the short arm of the protosex chromosome of the common ancestor, and then deletion and heterochromatization progressed on the sex-specific chromosome from the phylogenetically primitive boids to the more advanced viperids.

Animals↗
PubMed1998

The location of Z- and W-linked marker genes and sequence on the homomorphic sex chromosomes of the ostrich and the emu.

Perhaps the most striking fact about early Cenozoic avian history some 70 million years ago was the rapid radiation of large, flightless, ground-living birds. It has been suggested that, for a time, there was active competition between these large terrestrial birds and the early mammals. Probably reflecting the above noted early start of Ratitae of the infraclass Eoaves, the presumptive sex chromosomes of their present day survivors, such as the emu and the ostrich, largely remained homomorphic. The signs of genetic differentiation between their still-homomorphic Z and W chromosomes were tested by using two marker genes (Z-linked ZOV3 and the gene for the iron-responsive element-binding protein) and one marker sequence of a part of a presumptive pseudogene (W-linked EE0.6 of the chicken). Their homologues, maintaining 71-92% identities to the chicken counterparts, were found in both the emu (Dromaius novaehollandiae) and the ostrich (Struthio camelus). Their locations were visualized on chromosome preparations by fluorescence in situ hybridization. In the case of the emu, these three marker sequences were localized on both members of the fifth pair of a female, thus revealing no sign yet of genetic differentiation between the Z and the W. The finding was the same with regard to both members of the fourth pair of male ostriches. In the female ostrich, however, the sequence of the gene for the iron-responsive element-binding protein was missing from one of the pairs, thus revealing the differentiation by a small deletion of the W from the Z.

Animals↗
PubMed2005

Preferential elimination of repeated DNA sequences from the paternal, Nicotiana tomentosiformis genome donor of a synthetic, allotetraploid tobacco.

Nicotiana tabacum (tobacco, 2n = 4x = 48) is a natural allotetraploid combining two ancestral genomes closely related to modern Nicotiana sylvestris and Nicotiana tomentosiformis. Here we examine the immediate consequences of allopolyploidy on genome evolution using 20 S4-generation plants derived from a single synthetic, S0 plant made by Burk in 1973 (Th37). Using molecular and cytogenetic methods we analysed 14 middle and highly repetitive sequences that together total approximately 4% of the genome. Two repeats related to endogenous geminiviruses (GRD5) and pararetroviruses (NtoEPRV), and two classes of satellite repeats (NTRS, A1/A2) were partially or completely eliminated at variable frequency (25-60%). These sequences are all from the N. tomentosiformis parent. Genomic in situ hybridization revealed additivity in chromosome numbers in two plants (2n = 48), while a third was aneuploid for an N. tomentosiformis-origin chromosome (2n = 49). Two plants had homozygous translocations between chromosomes of the S- and T-genomes. * The data demonstrate that genetic changes in synthetic tobacco were fast, targeted to the paternal N. tomentosiformis-donated genome, and some of the changes showed concordance with changes that presumably occurred during evolution of natural tobacco.

Biological Evolution↗
PubMed2006

Plasticity of hepatic cell differentiation: bipotential adult mouse liver clonal cell lines competent to differentiate in vitro and in vivo.

In fetal liver, bipotential hepatoblasts differentiate into hepatocytes and bile duct cells (cholangiocytes). The persistence of such progenitor cells in adult mouse liver is still debated. In damaged liver of adult murine animals, when hepatocyte proliferation is compromised, bipotential oval cells emerge, probably from bile ducts, proliferate, and differentiate to regenerate the liver. However, treatment to elicit oval cell proliferation is not necessary to obtain bipotential stem cells from adult mouse liver. Here, we have isolated bipotential clonal cell lines from healthy liver of 8-10-week-old C57BL/6 mice. Primary cultures established from hepatocyte-enriched suspensions were characterized by time-lapse image acquisition, immunocytology, and RNA transcript analysis. Although hepatocytes dedifferentiated with loss of apical polarity and other hepatocyte markers, they rapidly activated expression of bile duct/oval cell markers. Reversibility of these processes was achieved in part by culture under dilute Matrigel or by aging of confluent cultures. Cell lines were obtained at high frequency from mass cultures, from isolated colonies, and by primary cloning of the hepatocyte-enriched suspension. Cells of the clonal cell lines do not grow in soft agar and are nontumorigenic, and they express cytokeratin 19, A6 antigen, and alpha6 integrin, as well as a large panel of hepatocyte functions. Furthermore, they can participate in liver regeneration in albumin-urokinase-type plasminogen activator/severe combined immune-deficient mice, where they differentiate in clusters of hepatocytes and occasionally bile ducts. These results demonstrate the existence, in normal adult mouse liver, of a significant pool of clonogenic cells that are (or can become) bipotential.

Animals↗
PubMed1989

Myelomonocytic myeloma cell line (LB 84-1).

A human cell line (LB 84-1) has been established from the bone marrow of a patient with Bence-Jones myeloma. Coexpression of plasma cell (Leu[CD38]) and myelomonocytic antigens (Leu MI[CD15], Leu M5 [CD11c], MY7 [CD13] plus butyrate and chloracetate esterase) proved to be an unusual but sustained feature of this cell line. The plasma cell phenotype with multinuclearity was retained. Shared major chromosomal abnormalities (del [5] [p14], t[5;?] [q35;?], del [6] [q21], and del 7[q32]) between the direct and cell line karyotypes affirmed the LB 84-1 cell as being derived from the original patient myeloma clone. The mechanisms potentially responsible for the aberrant coexpressed phenotype are discussed. This myelomonocytic myeloma cell line will hopefully prove to be a valuable tool for the study of the genotypic and phenotypic evolution of human myeloma.

Antigens, Differentiation, Myelomonocytic↗
PubMed1987

Cytogenetic study of twelve human near-diploid breast cancers with chromosomal changes.

The karyotypes of 12 fresh breast cancers, including two of the male, selected for their near-diploidy and their slight number of anomalies, i.e. less than 10 rearranged chromosomes, are reported. A clonal evolution could be demonstrated in 4 cases. Most of chromosomal imbalances result from structural rearrangement, frequently after breakage in juxtacentromeric heterochromatin. There does not seem to exist a specific breakpoint, but many of the imbalances are recurrent. They are, by decreasing order of frequency: gain of 1q, (7 cases), losses of 11q, 16q and 1p (5 cases), losses of 8p and 13q (4 cases), gain of 8q and losses of 6q and 17p (3 cases). None of these anomalies can be regarded as primary, but they are likely to be selected because they confer a slight selective advantage for the carrier cells during the tumoral progression.

Breast Neoplasms↗