Presidential address: Sex and the single schistosome.
Explore the source record for details and available documents.
Animals↗
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.
The evolutionary genetics of a unisexual fish, Poecilia formosa.
Explore the source record for details and available documents.
Animals↗
Molecular refinement of gibbon genome rearrangements.
The gibbon karyotype is known to be extensively rearranged when compared to the human and to the ancestral primate karyotype. By combining a bioinformatics (paired-end sequence analysis) approach and a molecular cytogenetics approach, we have refined the synteny block arrangement of the white-cheeked gibbon (Nomascus leucogenys, NLE) with respect to the human genome. We provide the first detailed clone framework map of the gibbon genome and refine the location of 86 evolutionary breakpoints to <1 Mb resolution. An additional 12 breakpoints, mapping primarily to centromeric and telomeric regions, were mapped to approximately 5 Mb resolution. Our combined FISH and BES analysis indicates that we have effectively subcloned 49 of these breakpoints within NLE gibbon BAC clones, mapped to a median resolution of 79.7 kb. Interestingly, many of the intervals associated with translocations were gene-rich, including some genes associated with normal skeletal development. Comparisons of NLE breakpoints with those of other gibbon species reveal variability in the position, suggesting that chromosomal rearrangement has been a longstanding property of this particular ape lineage. Our data emphasize the synergistic effect of combining computational genomics and cytogenetics and provide a framework for ultimate sequence and assembly of the gibbon genome.
Animals↗
Chromosomal phylogeny of Robertsonian races of the house mouse on the island of Madeira: testing between alternative mutational processes.
The ancestral karyotype of the house mouse (Mus musculus) consists of 40 acrocentric chromosomes, but numerous races exist within the domesticus subspecies characterized by different metacentric chromosomes formed by the joining at the centromere of two acrocentrics. An exemplary case is present on the island of Madeira where six highly divergent chromosomal races have accumulated different combinations of 20 metacentrics in 500-1000 years. Chromosomal cladistic phylogenies were performed to test the relative performance of Robertsonian (Rb) fusions, Rb fissions and whole-arm reciprocal translocations (WARTs) in resolving relationships between the chromosomal races. The different trees yielded roughly similar topologies, but varied in the number of steps and branch support. The analyses using Rb fusions/fissions as characters resulted in poorly supported trees requiring six to eight homoplasious events. Allowance for WARTs considerably increased nodal support and yielded the most parsimonious trees since homoplasy was reduced to a single event. The WART-based trees required five to nine WARTs and 12 to 16 Rb fusions. These analyses provide support for the role of WARTs in generating the extensive chromosomal diversification observed in house mice. The repeated occurrence of Rb fusions and WARTs highlights the contribution of centromere-related rearrangements to accelerated rates of chromosomal change in the house mouse.
Animals↗
Prospective follow-up study of 877 children born after intracytoplasmic sperm injection (ICSI), with ejaculated epididymal and testicular spermatozoa and after replacement of cryopreserved embryos obtained after ICSI.
A prospective follow-up study of 877 children born after ICSI was carried out. The aim of this study was to compile data on karyotypes, congenital malformations, growth parameters and developmental milestones so as to evaluate the safety of this new technique. The follow-up study included agreement to genetic counselling and prenatal diagnosis and was based on a physical examination at the Centre for Medical Genetics (Dutch-speaking Brussels Free University, Brussels, Belgium) at 2 months, 1 year and 2 years, when major and minor malformations and a psychomotor evolution were recorded. Between April 1991 and July 1995, 904 pregnancies obtained after intracytoplasmic sperm injection (ICSI) led to the birth of 877 children (465 singletons, 379 twins and 33 triplets). Prenatal diagnosis determined a total of 486 karyotypes, of which six were abnormal (1.2%) and six (1.2%) were familial structural aberrations, all transmitted from the father. This slight increase in de-novo chromosomal aberrations and the higher frequency of transmitted chromosomal aberrations are probably linked directly to the characteristics of the infertile men treated rather than to the ICSI procedure itself. In all, 23 (2.6%) major malformations were observed in the children born, defined as those causing functional impairment or requiring surgical correction. No particular malformation was disproportionately frequent. Compared with most registers of children born after assisted reproduction and with registers of malformation in the general population, the figure of 2.6% was within the expected range. These observations should be further completed by others and by collaborative efforts. In the meantime, patiens should be counselled about the available data before any treatment: the risk of transmitted chromosomal aberrations, the risk of de-novo, mainly sex chromosomal, aberrations and the risk of transmitting fertility problems to the offspring. Patients should also be reassured that there seems to be no higher incidence of congenital malformations in children born after ICSI.
Congenital Abnormalities↗
Chromosomal distributions of breakpoints in cancer, infertility, and evolution.
We extract 11 genome-wide sets of breakpoint positions from databases on reciprocal translocations, inversions and deletions in neoplasms, reciprocal translocations and inversions in families carrying rearrangements and the human-mouse comparative map, and for each set of positions construct breakpoint distributions for the 44 autosomal arms. We identify and interpret four main types of distribution: (i) a uniform distribution associated both with families carrying translocations or inversions, and with the comparative map, (ii) telomerically skewed distributions of translocations or inversions detected consequent to births with malformations, (iii) medially clustered distributions of translocation and deletion breakpoints in tumor karyotypes, and (iv) bimodal translocation breakpoint distributions for chromosome arms containing telomeric proto-oncogenes.
Animals↗
[Chromosomal studies in metastatic neuroblastoma].
Chromosomes were prepared directly from primary tumor and bone marrow aspirates of an 8 months old infant and a 2 years old boy with metastatic neuroblastoma. A total of 765 tumor metaphases were counted after Giemsa-banding and partially karyotyped. "Double minute" chromosomes were found in the metaphases of both primary tumor and metastases of the infant, but only in the primary tumor of the older child. In both patients, structural imbalances (in addition to other translocations) were seen in the short arm of chromosome no. 1. The modal chromosome number was 46 in the infant's primary tumor and bone marrow metastases, but 84 in the primary tumor and 46 and over 100 in the bone marrow metastasis of the older child. Clonal evolution of metastasizing neuroblastoma cells is discussed.
Adrenal Gland Neoplasms↗
Complex chromosomal rearrangements in an unusual variant of hairy cell leukemia.
An unusual case of variant HCL with multiple ribosomal lamellar complexes and complex chromosomal changes is described. The karyotype of the main cell clone is characterized by involvement of chromosome 5 at q13.3 and interstitial deletion of 7q. However, there is no other evidence of myelodysplasia and the abnormal cells are of lymphoid origin with a B-cell immunophenotype. The clonal chromosomal evolution involves rearrangements at sites known to be specifically altered in lymphoid tumors.
Aged↗
Chromosomal characteristics of rDNA in European grayling Thymallus thymallus (Salmonidae).
The chromosomal characteristics, locations and variations of two classes of ribosomal DNA (5S and 18S) were studied in European grayling karyotype (Thymallus thymallus, Salmonidae). Major rDNA sites as revealed by sequential CMA3/Ag staining and confirmed by in situ hybridization with a 18S rDNA probe were situated in two loci and were found to be polymorphic in size and displaying several distinct forms. The 5S rDNA was located by PRINS on three pairs of subtelocentric chromosomes, additional minor signal was present at the centromere of one metacentric element. 5S sites were not associated with NORs. The dosage compensation mechanism was proposed as an explanation of high frequency of lethal rDNA-deleted forms of the NOR-bearing chromosomes. Double variable pattern in the number and location of NORs supported the bi-directional evolution of salmonid rDNA loci.
Animals↗
Karyotype characterization of three species of the genus Trichomycterus (Teleostei, Siluriformes) from Iguaçu river basin.
Three species belonging to the genus Trichomycterus were collected from Iguaçu river basin and analyzed from the cytogenetic point of view. Although the species studied had the same diploid number 2n = 54 chromosomes and fundamental number 108, they differed in their karyotypic formulae. C-band patterns showed presence of specific-species markers in T. davisi and T. stawiarski. Results of analysis from the nucleolus organizer region, obtained by silver nitrate staining and CMA3, showed that size heteromorphism observed in this region may be due to gene duplication. Evolution aspects of the Trichomycteridae family and the presence of B chromosome in T. davisi are discussed.
Animals↗
Study on karyotype and occurrence of B chromosomes in two endemic species of the genus Pimelodus (Siluriformes, Pimelodidae) from the river Iguaçu.
The current work describes, for the first time, the occurrence of B chromosomes in the genus Pimelodus. Cytogenetic analysis in P. ortmanni and Pimelodus sp., from the river Iguaçu basin, revealed a diploid number of 56 chromosomes. Whereas distribution pattern of C-banding in Pimelodus sp. showed predominance of heterochromatin at the two extremities of several pairs of chromosomes, centromere markings predominated in P. ortmanni. Additional chromosomes in the two species were observed with numerical intra-individual variations between zero and four B, together with interspecies differences in their frequency. In Giemsa-stained metaphases two distinct morphological types of B chromosomes were identified: Bm (B metacentric) and Ba (B acrocentric). In P. ortmanni both types of B chromosomes were totally heterochromatic; the Bm type in Pimelodus sp. had heterochromatin throughout its entire extension; the Ba type was partially heterochromatic with telomere markings on the long arm.
Animals↗
Karyomorphology of Maianthemum sensu lato (Polygonatae, Ruscaceae).
We report results of karyotype analyses using nine species of Maianthemum from China. The species, except M. atropurpureum (with 2n=72), had 2n=36, and the results support the earlier suggestion that Maianthemum has x=18 with 2n=36 in most species. The species examined, however, showed marked differences in karyotype, particularly in the numbers of metacentric, submetacentric, and acrocentric chromosomes as well as in the number of satellites. In addition, we distinguished three different modes based on the number of clear gaps in chromosome length variation: unimodal, bimodal, and trimodal. The unimodal variation (with no gap) was found in M. dahuricum and M. atropurpureum, the bimodal variation (with one gap) in M. tatsienense, and the trimodal variation (with two gaps) in M. bifolium, M. forrestii, M. japonicum, M. henryi, M. purpureum, and M. lichiangense. In the trimodal variation, the positions of the two gaps may differ from species to species. In addition, the frequency of acrocentric chromosomes per complement was generally higher in the trimodal variation than in the unimodal and bimodal variations. Results of our analyses, which had not been clearly presented prior to this, may provide a better understanding of species evolution in the tribe Polygonatae.
China↗
High-resolution comparative mapping among man, cattle and mouse suggests a role for repeat sequences in mammalian genome evolution.
BACKGROUND: Comparative mapping provides new insights into the evolutionary history of genomes. In particular, recent studies in mammals have suggested a role for segmental duplication in genome evolution. In some species such as Drosophila or maize, transposable elements (TEs) have been shown to be involved in chromosomal rearrangements. In this work, we have explored the presence of interspersed repeats in regions of chromosomal rearrangements, using an updated high-resolution integrated comparative map among cattle, man and mouse. RESULTS: The bovine, human and mouse comparative autosomal map has been constructed using data from bovine genetic and physical maps and from FISH-mapping studies. We confirm most previous results but also reveal some discrepancies. A total of 211 conserved segments have been identified between cattle and man, of which 33 are new segments and 72 correspond to extended, previously known segments. The resulting map covers 91% and 90% of the human and bovine genomes, respectively. Analysis of breakpoint regions revealed a high density of species-specific interspersed repeats in the human and mouse genomes. CONCLUSION: Analysis of the breakpoint regions has revealed specific repeat density patterns, suggesting that TEs may have played a significant role in chromosome evolution and genome plasticity. However, we cannot rule out that repeats and breakpoints accumulate independently in the few same regions where modifications are better tolerated. Likewise, we cannot ascertain whether increased TE density is the cause or the consequence of chromosome rearrangements. Nevertheless, the identification of high density repeat clusters combined with a well-documented repeat phylogeny should highlight probable breakpoints, and permit their precise dating. Combining new statistical models taking the present information into account should help reconstruct ancestral karyotypes.
Animals↗
Molecular estimates of primate divergences and new hypotheses for primate dispersal and the origin of modern humans.
The concept of recent hominoid divergences has been a mainstay in molecular primatology since the 1970's. However, the ages allocated to the calibration points used to establish these divergence times and the estimates resulting from their application, notably the commonly accepted divergence between Pan (chimpanzees) and Homo 5 million years before present (MYBP), are now palaeontologically refutable. Here we estimate the ages of various primate divergences using three references with a more detailed fossil record than any of the traditional primate calibration points. Our findings suggest that the latter yield datings that are too recent by a factor of about two. For example, our estimates place the divergence between Pan and Homo 10.5-13 MYBP. The revised estimates of primate divergence times suggest a new hypothesis for primate evolution and dispersal: that the divergence between strepsirhines (lorises, lemurs) and anthropoids was contemporary with the break-up of Southern continents about 90 MYBP, with strepsirhines becoming isolated on Madagascar and later dispersing to Africa (and Asia) and anthropoids evolving in South America and subsequently colonizing Africa (and Asia), or possibly North America. In addition we present a new hypothesis, which accommodates the strikingly similar coalescence times for human mitochondrial DNA and the Y-chromosome. This hypothesis posits a common mitochondrial and Y-chromosome bottleneck about 400,000 years ago, associated with the origination of the human 2n = 46 karyotype, obstructing genetic exchange with the 2n = 48 Homo contemporaries.
Africa↗
Clonal cytogenetic abnormalities in Philadelphia chromosome negative cells in chronic myeloid leukemia patients treated with imatinib.
Treatment of chronic myeloid leukemia (CML) with imatinib (Gleevec) induces a much higher rate of partial and complete cytogenetic responses (CCR) than interferon-alpha (IFN)-based therapies. Conventional wisdom suggests that elimination of the Philadelphia (Ph)- positive cells will lead to re-establishment of normal Ph-negative hematopoiesis. Surprisingly, karyotypic abnormalities were detected in the chromosome negative cells of some patients with cytogenetic response to imatinib. In some cases, this was associated with a myelodysplastic syndrome (MDS). While clonal evolution in Ph-positive cells is considered part of the progression of CML, clonal evolution in Ph-negative cells had been observed only rarely in a small number of patients treated with IFN or bone marrow transplantation, raising the question whether the phenomenon may be causally linked to imatinib therapy. In this manuscript, we will review the currently available data, suggest possible causes and discuss potential implications for patient management. We are fully aware that a systematic study of a larger patient cohort will be required to conclusively address these issues.
Benzamides↗
Cytogenetic characterization of several androgen responsive and unresponsive sublines of the human prostatic carcinoma cell line LNCaP.
The cytogenetic evolution of the prostatic adenocarcinoma cell line LNCaP was investigated during long term in vitro culture. Study of five different sublines demonstrated that the original karyotype was well preserved in all sublines, with respect to the chromosome number as well as to the primary markers. All sublines showed additional, subline specific secondary marker chromosomes. Comparison of these markers in androgen responsive and nonresponsive sublines showed rearrangement of the short arm of chromosome 8 in both unresponsive sublines. The breakpoints were in 8p21 and 8p23, respectively, resulting in deletion of the 8p23----pter region in both sublines. In contrast, the hormone responsive sublines did not show any aberrations in chromosome 8. Review of published karyotypes of patients and cell lines seems to support our finding of partial deletion of 8p in androgen unresponsive prostate tumor cells.
Androgens↗
Multiple clonal chromosome abnormalities in Peyronie's disease.
Numerical and structural chromosome aberrations were found in cell plaque metaphases from 9 of 14 patients with Peyronie's disease. In two cases there was evidence of clonal evolution for some of the chromosomal aberrations observed. The Y chromosome was the most frequently involved in numerical changes. Four of 9 cases with abnormal karyotype showed more than one abnormal, cytogenetically unrelated clone. Our findings suggest the possibility of a multiclonal origin for this benign tumor, and confirm the presence of chromosome instability in this cell growth disorder.
Adult↗
Structural aberrations of chromosomes 17 and 12 in chronic B-cell disorders.
OBJECTIVES: Genomic aberrations can now be identified in approximately 80% of chronic lymphocytic leukemia, small lymphocytic lymphoma (CLL/SLL) patients. In the present study, four new structural changes involving chromosomes 17 and 12 in CLL/SLL patients are described. METHODS: Five patients were selected for inclusion in the present report among a total of 92 cases with diagnosis of CLL/SLL. Cytogenetic studies and fluorescence in situ hybridization (FISH) analysis to detect some of the most frequent cryptic aberrations occurring in CLL/SLL patients were performed. Clinical studies are also described. RESULTS: Four cases showed structural rearrangements of chromosome 17. A psu dic(17;2)(p11.2;p21), leading to p53 deletion, was observed in a patient who developed a mixed cellularity Hodgkin's disease coexisting with the CLL/SLL in the same lymph node. Epstein Barr virus was detected in the Reed-Sternberg cells. Two cases had a balanced translocation t(2;17)(p21;q23). Both patients showed trisomy 12 and clonal evolution and one of them also had 11q deletion. In addition, a der(17)t(12;17)(q13;q25) as a part of a complex karyotype, and a complex translocation t(5;12;19) (q15;p11;q13) were also found. Four patients had an adverse clinical outcome and died because of disease progression. CONCLUSIONS: Four unreported nonrandom chromosome aberrations in CLL/SLL patients, one of them who might represent a new recurrent abnormality, are described. These uncommon abnormalities, mostly associated with evolving disease, may have implications for the understanding of genetic events associated with disease progression in this pathology.
Aged↗