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PubMed2002

Characterization of supernumerary rings and giant marker chromosomes in well-differentiated lipomatous tumors by a combination of G-banding, CGH, M-FISH, and chromosome- and locus-specific FISH.

Supernumerary ring chromosomes and/or giant marker chromosomes are often seen in soft-tissue tumors of low-grade or borderline malignancy, such as well-differentiated liposarcomas or atypical lipomas. Classic cytogenetic banding techniques have proved insufficient to identify the genomic composition and structure of such rings and markers, but fluorescent in situ hybridization (FISH) studies have shown that they consist mainly of amplified material from chromosome 12, more specifically from bands 12q13-->q15. We have used the new FISH-based screening techniques comparative genomic hybridization (CGH) and multicolor-FISH (M-FISH) in combination with G-banding and analysis by chromosome- and locus-specific fluorescent in situ probes to examine in detail the karyotypic characteristics of 22 lipomatous tumors, most of them classified histologically as well-differentiated liposarcomas, selected because they had been shown to harbor rings and/or marker chromosomes. M-FISH, in contrast to G- banding, was found to be informative with regard to the chromosomal origin of the rings and other markers present, whereas CGH and hybridizations with locus-specific probes helped identify which subchromosomal regions were involved. We found that chromosome bands 12q15-->q21 were always gained, with 12q15-->q21 being amplified (i.e., a green-to-red ratio >2 by CGH) in 14 of 22 tumors. In three tumors, two distinct but close amplicons in 12q could be identified, corresponding to bands 12q13-->q15 and 12q21. The genomic segment 1q21-->q23 was gained in 12 cases, reaching the level of amplification in seven. Bands 6q24 and 7p15, whose pathogenetic involvement in liposarcomas has not been reported previously, were gained in three cases each. In addition, the rings and giant markers often contained interspersed sequences from several other chromosomes that did not give an equally clear impression of being nonrandomly involved.

Biomarkers, Tumor↗
PubMed2003

Chromosome banding in Amphibia. XXVIII. Homomorphic XY sex chromosomes and a derived Y-autosome translocation in Eleutherodactylus riveroi (Anura, Leptodactylidae).

Extensive cytogenetic analyses on a population of the leptodactylid frog Eleutherodactylus riveroi in northern Venezuela revealed the existence of multiple XXAA male/XYAA female/XAA(Y) female sex chromosomes. The XAA(Y) karyotype originated by a centric (Robertsonian) fusion between the original, free Y chromosome and an autosome. 46.2% of the male individuals in this population are carriers of this Y-autosome fusion. In male meiosis the XAA(Y) sex chromosomes pair in the expected trivalent configuration. In the same population 53.8% of the male animals still possess the original, free XY sex chromosomes. E. riveroi is only the second vertebrate species discovered in which a derived Y-autosome fusion coexists with the ancestral free XY sex chromosomes. The free XY sex chromosomes, as well as the multiple XA(Y) sex chromosomes are still in a very primitive (homomorphic) stage of differentiation. With no banding technique applied it is possible to distinguish the Y from the X. Various banding techniques and in situ hybridizations have been carried out to characterize the karyotypes. DNA flow cytometric measurements show that the genome size of E. riveroi resembles that of other Eleutherodactylus species. The cytogenetic data obtained in E. riveroi are compared with those of the sole other vertebrate known to possess the extremely rare, multiple XXAA male/XYAA female/XAA(Y) female sex chromosomes. Surprisingly enough, this vertebrate again is a frog belonging to the genus Eleutherodactylus [E. ((maussi) biporcatus] which lives exactly in the same habitat in northern Venezuela as does E. riveroi.

Animals↗
PubMed1984

Masked Philadelphia chromosome due to the translocation (1q-;22q +) and small chromosome 19 in a case of acute leukemia.

The case of a 51-year-old female with acute myelomonocytic leukemia (AMMoL) and masked Philadelphia (Ph1) chromosome is reported. The Ph1 resulted from a translocation involving chromosomes 1 and 22, in which a segment of the long arm of one chromosome 1 (1q12----q25) was translocated to the long arm of one chromosome 22 at band 22q11. Additionally, a marker chromosome of unknown origin and deletion of the long arm of one chromosome 19 at band 19q12 were found. The literature on masked Ph1 chromosomes and changes of chromosomes 1 and 19 is briefly summarized.

Chromosome Deletion↗
PubMed1996

Localization by chromosome microdissection of a recurrent breakpoint region on chromosome 6 in human B-cell lymphoma.

Deletion of the long arm of chromosome 6 (6q) is one of the most common chromosomal alterations in human B-cell lymphomas. Conventional cytogenetic banding analysis and loss-of-heterozygosity (LOH) studies have detected several common regions of deletion ranging across the entire long arm (6q), with no defined recurrent breakpoint yet identified. We describe here a strategy combining chromosome microdissection and fluorescence in situ hybridization (Micro-FISH) to determine a minimal region of deletion along chromosome 6. Seven clinical cases and one cell line of follicular lymphoma containing a t(14;18) and one case of diffuse lymphoma, also with a t(14;18), were used for this study. All nine cases had previously defined abnormalities of chromosome 6 determined by cytogenetic analysis. The results of chromosome dissection were unexpected and in contrast to the suggestion of disparate breakpoints by conventional chromosome banding. Specifically, Micro-FISH analysis provided evidence for a common breakpoint at 6q11 in seven of nine cases. After Micro-FISH analysis, all of the presumed simple deletions of chromosome 6 were carefully reanalyzed and shown to actually represent either nonreciprocal translocations (three cases), interstitial deletions (five cases), or isochromosome (one case). The recurrent proximal breakpoint (6q11) was detected in seven of nine cases, with the minimal region of deletion encompassing 6q11 to 6q21. By analogy to other tumor systems, the identification of recurring breakpoints within 6q11 may suggest that a gene(s) important to the genesis or progression of follicular lymphoma can be localized to this band region.

Chromosome Aberrations↗
PubMed1983

The mei-9a test for chromosome loss in Drosophila: a review of assays of 21 chemicals for chromosome breakage.

In Drosophila, detection of chemical-induced chromosome breakage for many compounds in conventional chromosome loss or reciprocal translocation (RT) tests requires considerably higher concentrations than for sex-linked recessive lethals, or fails entirely even at concentrations giving substantial to high rates of recessive lethals. Accordingly, relatively high LDs may be necessary before evidence of chromosome breakage is observed raising questions of "false positives" resulting, for example, from aberrant metabolic effects/products not found at lower concentrations. In the test for chromosome loss, definitive scoring is made in F1 progeny. In contrast, an F2 and often an F3 is required to bring the RT test to completion. Further, the RT test is prone to "false negatives" in many cases unless testing is carried out on sperm stored in the female for several days (or longer). Accordingly, efforts in this laboratory have been directed toward improvements in the sensitivity of the test for chromosome loss. Major advances have been made by using excision repair deficient mei-9a females as P1 females to which treated males are mated. For purposes of testing, ring-X males carrying the doubly marked Y chromosome, BSYy+, were treated or not, mated for 3 days with ordinary (repair-proficient) females (the conventional test) or with mei-9a females (the mei-9a test) and all P1s discarded. Data are reported for this period only--viz, on unstored sperm. F1 progeny were scored for complete loss (CL) of the X or Y (loss is principally of the ring-X) and partial loss of the Y (PL)--viz, loss of BS or y+. Partial loss of the Y chromosome was taken as strong evidence of chromosome breakage, whereas loss of the ring-X was regarded alternatively as break-related or resulting from the production of sister chromatid exchanges. Of the 21 compounds tested, 17 are classified as carcinogens and four are unknown in this regard. At the concentration reported, 21/21 compounds were positive for CL+PL and 21/21 for PL in the mei-9a test. At the same concentration, only 10/20 compounds were positive for CL and PL and 2/21 compounds for PL with repair proficient females; the mei-9a test is clearly more sensitive than the conventional test for chromosome breakage.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1975

Chromosome banding pattern conservatism in birds and nonhomology of chromosome banding patterns between birds, turtles, snakes and amphibians.

The G-banded karyotypes of 4 species of birds representing the orders Galliformes, Columbiformes and Musophagiformes were compared. Banding pattern homology between orders was limited t 5o 5 major chromosome arms and the Z chromosome. Even in these major chromosome arms pericentric and paracentric inversions produced alteration of the banding pattern sequences. Addition of constitutive heterochromatin was responsible for changes in banding patterns in the Z chromosome. The chromosome banding patterns of an emydid turtle, Terrepene carolina, 5 species of boid snakes of the genera Liasis, Acrantophis, and Sanzinia and the African clawed-frog. Xenopus muelleri, were also compared to the bird chromosome banding patterns. No homology was observed between any of these major groups: bird, snake, turtle, amphibian. However, intergroup homology was apparent. - The data obtained do not support reports of broad interordinal direct homology of the macrochromosomes of birds and refutes the idea of a primitive bird karyotype with 3 pairs of "Agroup' chromosomes and 3 pairs of "B group' chromosomes. - The major mechanisms responsible for chromosome evolution in birds appear to be centric and tandem fusions, paracentric and pericentric inversions, and addition or deletion of heterochromatin.

Animals↗
PubMed1984

Sex chromosome positions in human interphase nuclei as studied by in situ hybridization with chromosome specific DNA probes.

Two cloned repetitive DNA probes, pXBR and CY1, which bind preferentially to specific regions of the human X and Y chromosome, respectively, were used to study the distribution of the sex chromosomes in human lymphocyte nuclei by in situ hybridization experiments. Our data indicate a large variability of the distances between the sex chromosomes in male and female interphase nuclei. However, the mean distance observed between the X and Y chromosome was significantly smaller than the mean distance observed between the two X-chromosomes. The distribution of distances determined experimentally is compared with three model distributions of distances, and the question of a non-random distribution of sex chromosomes is discussed. Mathematical details of these model distributions are provided in an Appendix to this paper. In the case of a human translocation chromosome (Xqter----Xp22.2::Yq11----Yqter) contained in the Chinese hamster X human hybrid cell line 445 X 393, the binding sites of pXBR and CY1 were found close to each other in most interphase nuclei. These data demonstrate the potential use of chromosome-specific repetitive DNA probes to study the problem of interphase chromosome topography.

Cell Nucleus↗
PubMed1996

The effect of Y-chromosome alpha-satellite array length on the rate of sex chromosome disomy in human sperm.

Trisomy is the leading known cause of mental retardation and pregnancy loss in humans, yet virtually nothing is known of the underlying nondisjunctional mechanisms. Since studies of other organisms suggest an association between centromere size or sequence and meiotic nondisjunction, we recently initiated studies to examine the effect of centromere size variation on human nondisjunction. In the present report, we summarize studies correlating variation in the size of the Y-chromosome centromere with sex chromosome nondisjunction. In one set of studies, we used pulsed-field gel electrophoresis to estimate Y-chromosome alpha-satellite array lengths in normal males, and correlated these values with Y-chromosome sperm disomy levels as determined by fluorescence in situ hybridization. In a second set of studies, we determined the Y-chromosome alpha-satellite array length of 47,XYY males, since the karyotypes of these individuals are a consequence of Y chromosome nondisjunction. Neither set of studies provided evidence for an effect of Y-chromosome alpha-satellite array length on Y-chromosome nondisjunction. Thus, if there is an association between Y-chromosome centromere size and nondisjunction, the effect is subtle and below the detection levels of the present study or involves extreme size variants that were not represented in the present study population.

Aneuploidy↗
PubMed2006

Hybrid lethality in interspecific hybrids between Nicotiana tabacum and N. suaveolens: evidence that the Q chromosome causes hybrid lethality based on Q-chromosome-specific DNA markers.

Hybrid seedlings from the cross Nicotiana tabacum x N. suaveolens express lethality at 28 degrees C. We carried out a cross between monosomic lines of N. tabacum lacking the Q chromosome and N. suaveolens by test-tube pollination and ovule culture at 28 degrees C. To suppress hybrid lethality, hybrid seedlings obtained were transferred to 36 degrees C immediately after germination and cultured. We determined whether Q-chromosome-specific DNA markers were detected among hybrid seedlings. When hybrid seedlings cultured at 36 degrees C were transferred to 28 degrees C, hybrid seedlings in which Q-chromosome-specific DNA markers were detected expressed hybrid lethality, while hybrid seedlings in which Q-chromosome-specific DNA markers were not detected did not express hybrid lethality. From these results, we concluded that the presence of the Q chromosome of N. tabacum is related to hybrid lethality observed in crosses between N. tabacum and N. suaveolens. This is the first report that clearly demonstrates the relationship between a certain chromosome and hybrid lethality in the genus Nicotiana using chromosome-specific DNA markers. Additionally, we confirmed that the Q chromosome belongs to the S subgenome because Q-chromosome-specific DNA markers were detected only in N. sylvestris.

Chromosomes, Plant↗
PubMed2000

Centromere association is an unlikely mechanism by which the wheat Ph1 locus regulates metaphase I chromosome pairing between homoeologous chromosomes.

Chiasmate pairing between homoeologous chromosomes at metaphase I (MI) of meiosis in wheat is prevented by the activity of the Ph1 locus on chromosome 5B. Several hypotheses have been proposed sharing the assumption that Ph1 regulates MI chromosome pairing by regulating centromere-mediated chromosome alignment before the onset of meiosis. To test the relevance of the putative predetermination of chromosome pairing at MI by the centromere-mediated chromosome association prior to meiosis, a 2BL.2RL homoeoisochromosome was constructed and its MI pairing was assessed in the presence and absence of the Ph1 locus. Although the 2BL and 2RL arms of the homoeoisochromosome paired with each other at MI in the absence of Ph1, they never paired with each other at MI in the presence of Ph1. Since the two arms were permanently associated in the homoeoisochromosome via a common centromere, it is unlikely that Ph1 predetermines MI pairing between homoeologous chromosomes solely by controlling premeiotic association of centromeres. These findings are consistent with the idea that Ph1 determines the chromosome pairing pattern at MI by scrutinizing homology across the entire chromosome.

Centromere↗
PubMed2005

Population structure of Y chromosome SNP haplogroups in the United States and forensic implications for constructing Y chromosome STR databases.

A set of 61 Y chromosome single-nucleotide-polymorphisms (Y-SNPs) is typed in a sample of 2517 individuals from 38 populations to infer the geographic origins of Y chromosomes in the United States and to test for paternal admixture among African-, European-, Hispanic-, Asian-, and Native-Americans. All of the samples were previously typed with the 11 core U.S. Y chromosome short tandem repeats (Y-STRs) recommended by SWGDAM, which revealed high levels of among ethnic group variation and low levels of among-population-within-ethnic-group variation. Admixture estimates vary greatly among populations and ethnic groups. The frequencies of non-European (3.4%) and non-Asian (4.5%) Y chromosomes are generally low in European-American and Asian-American populations, respectively. The frequencies of European Y chromosomes in Native-American populations range widely (i.e., 7-89%) and follow a West to East gradient, whereas they are relatively consistent in African-American populations (26.4+/-8.9%) from different locations. The European (77.8+/-9.3%) and Native-American (13.7+/-7.4%) components of the Hispanic paternal gene pool are also relatively constant among geographic regions; however, the African contribution is much higher in the Northeast (10.5+/-6.4%) than in the Southwest (1.5+/-0.9%) or Midwest (0%). To test for the effects of inter-ethnic admixture on the structure of Y-STR diversity in the U.S., we perform subtraction analyses in which Y chromosomes inferred to be admixed by Y-SNP analysis are removed from the database and pairwise population differentiation tests are implemented on the remaining Y-STR haplotypes. Results show that low levels of heterogeneity previously observed between pairs of Hispanic-American populations disappear when African-derived chromosomes are removed from the analysis. This is not the case for an unusual sample of European-Americans from New York City when its African-derived chromosomes are removed, or for Native-American populations when European-derived chromosomes are removed. We infer that both inter-ethnic admixture and population structure in ancestral source populations may contribute to fine scale Y-STR heterogeneity within U.S. ethnic groups.

Analysis of Variance↗
PubMed2006

The 1.6Mb chromosome carrying the avirulence gene AvrPik in Magnaporthe oryzae isolate 84R-62B is a chimera containing chromosome 1 sequences.

A genetic map was constructed previously from a cross between Magnaporthe oryzae isolates 84R-62B and Y93-245c-2, and genetic markers closely linked to the cultivar-specific avirulence (Avr) gene, AvrPik, were assigned to a 1.6Mb small chromosome of 84R-62B that is absent from Y93-245c-2. In the present study, the 1.6Mb chromosome was characterized by using contour-clamped homogeneous electric fields (CHEF) electrophoresis and hybridization analysis. CHEF electrophoresis analysis showed that the 1.6Mb chromosome was inherited in Mendelian fashion, and co-segregated with AvrPik. Southern hybridization analysis revealed that the 1.6Mb chromosome carried sequences only distributed to the supernumerary chromosome in M. oryzae isolates, as well as sequences corresponding to those in the supercontig 17 of chromosome 1 in the M. grisea database. Thus, we conclude that the Mendelian 1.6Mb chromosome is a chimera containing sequences from chromosome 1 and from supernumerary chromosomes in M. oryzae.

Blotting, Southern↗
PubMed2002

Application of mFISH for the analysis of chemically-induced chromosomal aberrations: a model for the formation of triradial chromosomes.

Using a human lymphoblastoid cell line WTK-1, we applied multicolor fluorescence in situ hybridization (mFISH) technique to analyze mitomycin C (MMC)-induced chromatid exchanges, focusing especially on the triradial chromosomes. It was found that the triradial chromosomes were formed with a specific rearrangement, "recipient and donor" relationship. The exchange sites of the recipient chromosomes were on single chromatid breaks and distributed randomly throughout the interstitial, pericentromeric, and terminal regions. In counterpart, donor chromosomes exchanged on isochromatid breaks of their telomeric and/or subtelomeric regions with the single chromatid breaks of recipient chromosomes. More than 80% of the scored triradial chromosomes were formed with such rearrangements, and few acentric chromosome fragments derived from the donor chromosomes could be detected in the metaphases observed. We therefore suggest that biological mechanisms of breakages between the recipient and donor chromosomes are different: the former due to direct DNA-damage by MMC, but the latter due to indirect DNA-damage depending on telomeric specific structure/function.

Alkylating Agents↗
PubMed1997

A case of acute lymphoblastic leukemia, near-triploidy, and poor outcome: characterization by fluorescence in situ hybridization using chromosome-specific libraries from all human chromosomes.

We have applied fluorescence in situ hybridization (FISH) using chromosome-specific libraries from all 24 chromosomes on metaphase spreads from bone marrow cells, in order to resolve the chromosomal changes in leukemic cells from a 10-year-old boy with acute lymphoblastic leukemia (ALL), near-triploidy, and a subsequent poor outcome. The FISH analysis revealed a pattern of chromosome gains and losses that differed from all cases previously described. Most of the affected chromosomes were present in three copies (trisomy for chromosomes 1, 2, 5, 6, 7, 11, 12, 13, 14, 16, 17, 18, 19, 20, and 22), but the patient had four copies of chromosomes 8 and 21, two copies of chromosomes 3, 4, 9, 10, 15, and X, and one Y chromosome. No structural abnormalities could be detected. Thus, the karyotype of the malignant clone was 66,XXY-3,-4,+8,-9,-10,-15,+21.

Child↗
PubMed2000

Fate of multicentric and ring chromosomes induced by a new gametocidal factor located on chromosome 4Mg of Aegilops geniculata.

A new gametocidal (Gc) factor was identified on chromosome 4Mg of Aegilops geniculata Roth. When transferred to Chinese Spring wheat, monosomic and disomic Triticum aestivum-Ae. geniculata chromosome 4Mg addition plants undergo regular first and second meiotic divisions. Male gametogenesis in disomic 4Mg addition plants also is normal. However, chromosome breakage and anaphase bridges were observed at ana/telophase of the first (29%) and second (11%) pollen mitosis in monosomic 4Mg addition plants. Gc-induced multicentric and ring chromosomes can be transmitted to the offspring and initiate breakage fusion bridge (BFB) cycles in dividing root tip meristem cells of the derived sporophytes. The fate of multicentric and ring chromosomes was analyzed in root meristems at different time intervals after seed germination. The majority of the BFB cycles ceased about 32 days after germination. Broken chromosome ends were healed either by the fusion of a centric and an acentric fragment forming terminal translocation chromosomes or as deficiencies or telocentric chromosomes. Lack of cytologically detectable telomeric repeats at the stabilized newly broken termini suggests that chromosome healing by addition of telomeric repeats may be a gradual process.

Centromere↗
PubMed2004

The SHR Y-chromosome increases testosterone and aggression, but decreases serotonin as compared to the WKY Y-chromosome in the rat model.

The Spontaneously Hypertensive Rat (SHR) model was used to test the hypothesis that a locus on the SHR Y-chromosome is responsible for increased aggression resulting from increased serum testosterone and decreased amygdala serotonin content compared to the WKY Y-chromosome. To examine the Y-chromosome in SHR and WKY males, consomic Y-chromosome strains were used (WKY.SHR-Y and SHR.WKY-Y). Novel resident intruder tests and intra-colony scarring behavioral paradigms were used to measure aggression in a colony environment. Both resident intruder test attack number and wounding, along with intra-colony scarring scores showed the colony males with the SHR Y-chromosome (SHR and WKY.SHR-Y strains) were more aggressive than the colony males with the WKY Y-chromosome (WKY and SHR.WKY-Y strains). The SHR Y-chromosome colony male animals also had significantly higher serum testosterone, as well as overall lower amygdala serotonin content than the WKY Y-chromosome colony male animals. The results suggest that these behavioral and physiological differences between the SHR and WKY strains are a result of a mutation in the non-pseudoautosomal region unique to the Y-chromosome.

Aggression↗
PubMed2004

The mouse X chromosome is enriched for sex-biased genes not subject to selection by meiotic sex chromosome inactivation.

Sex chromosomes are subject to sex-specific selective evolutionary forces. One model predicts that genes with sex-biased expression should be enriched on the X chromosome. In agreement with Rice's hypothesis, spermatogonial genes are over-represented on the X chromosome of mice and sex- and reproduction-related genes are over-represented on the human X chromosome. Male-biased genes are under-represented on the X chromosome in worms and flies, however. Here we show that mouse spermatogenesis genes are relatively under-represented on the X chromosome and female-biased genes are enriched on it. We used Spo11(-/-) mice blocked in spermatogenesis early in meiosis to evaluate the temporal pattern of gene expression in sperm development. Genes expressed before the Spo11 block are enriched on the X chromosome, whereas those expressed later in spermatogenesis are depleted. Inactivation of the X chromosome in male meiosis may be a universal driving force for X-chromosome demasculinization.

Animals↗
PubMed2025

Germline-restricted chromosome of songbirds has different centromere compared to regular chromosomes.

Centromeres are an important part of chromosomes which direct chromosome segregation during cell division. Their modifications can therefore explain the unusual mitotic and meiotic behaviour of certain chromosomes, such as the germline-restricted chromosome (GRC) of songbirds. This chromosome is eliminated from somatic cells during early embryogenesis and later also from male germ cells during spermatogenesis. Although the mechanism of elimination is not yet known, it is possible that it involves a modification of the centromeric sequence on the GRC, resulting in problems with the attachment of this chromosome to the mitotic or meiotic spindle and its lagging during anaphase, which eventually leads to its elimination from the nucleus. However, the repetitive nature and rapid evolution of centromeres make their identification and comparative analysis across species and chromosomes challenging. Here, we used a combination of cytogenetic and genomic approaches to identify the centromeric sequences of two closely related songbird species, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (L. luscinia). We found a 436-bp satellite repeat present in the centromeric regions of all regular chromosomes (i.e., autosomes and sex chromosomes), making it a strong candidate for the centromeric repeat. This centromeric repeat was highly similar between the two nightingale species. Interestingly, hybridization of the probe to this satellite repeat on meiotic spreads suggested that this repeat is missing on the GRC. Our results indicate that the change of the centromeric sequence may underlie the unusual inheritance and programmed DNA elimination of the GRC in songbirds.

Animals↗