Homologies between X and Y charomosomes detected by DNA probes: localisation and evolution

Kœnig, M.; Moisan, Jean‐Paul; Heilig, Roland; Mandel, J.L.

doi:10.1093/nar/13.15.5485

Cited by 62 publications

(34 citation statements)

References 21 publications

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“…(2) loss of the X chromosome in a major subpopulation of the ACHN cell line, not detected by banding analysis, and (3) a relatively more intense painting of the X chromosome by homolog sequences of the Y chromosome contained in the control genome (46,XY), but not in the ACHN genome. Although recent findings indicate that homolog sequences are not restricted to the pseudoautosomal region (Koenig et al 1985;Page et al 1987), there is no evidence that such homologies would exist to an extent sufficient to explain the deviation in the measured FR. Indeed, chromosome painting using DNA from sorted Y chromosomes as a probe yields hybridization signals on Xp22.3 and Xql3, but does not result in a uniform X chromosome painting (Jauch eta].…”

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confidence: 88%

Detection of complete and partial chromosome gains and losses by comparative genomic in situ hybridization

et al. 1993

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Abstract. Comparative genomic in situ hybridization (CGH)provides a new possibility for searching genomes for imbalanced genetic material. Labeled genomic test DNA, prepared from clinical or tumor specimens, is mixed with differently labeled control DNA prepared from cells with normal chromosome complements. The mixed probe is used for chromosomal in situ suppression (CISS) hybridization to normal metaphase spreads (CGH-metaphase spreads). Hybridized test and control DNA sequences are detected via different fluorochromes, e.g., fluorescein isothiocyanate (FITC) and tetraethylrhodamine isothiocyanate (TRITC). The ratios of FITC/TRITC fluorescence intensities for each chromosome or chromosome segment should then reflect its relative copy number in the test genome compared with the control genome, e.g., 0.5 for monosomies, 1 for disomies, 1.5 for trisomies, etc. Initially, model experiments were designed to test the accuracy of fluorescence ratio measurements on single chromosomes. DNAs from up to five human chromosome-specific plasmid libraries were labeled with biotin and digoxigenin in different hapten proportions. Probe mixtures were used for CISS hybridization to normal human metaphase spreads and detected with FITC and TRITC. An epifluorescence microscope equipped with a cooled charge coupled device (CCD) camera was used for image acquisition. Procedures for fluorescence ratio measurements were developed on the basis of commercial image analysis software. For hapten ratios 4/1, 1/1 and 1/4, fluorescence ratio values measured for individual chromosomes could be used as a single reliable parameter for chromosome identification. Our findings indicate (1) a tight correlation of fluorescence ratio values with hapten ratios, and (2) the potential of fluorescence ratio measurements for multiple color chromosome painting. Subsequently, genomic test DNAs, prepared from aCorrespondence to: T. Cremer patient with Down syndrome, from blood of a patient with Tcell prolymphocytic leukemia, and from cultured cells of a renal papillary carcinoma cell line, were applied in CGH experiments. As expected, significant differences in the fluorescence ratios could be measured for chromosome types present in different copy numbers in these test genomes, including a trisomy of chromosome 21, the smallest autosome of the human complement. In addition, chromosome material involved in partial gains and losses of the different tumors could be mapped to their normal chromosome counterparts in CGH-metaphase spreads. An alternative and simpler evaluation procedure based on visual inspection of CCD images of CGH-metaphase spreads also yielded consistent results from several independent observers. Pitfalls, methodological improvements, and potential applications of CGH analyses are discussed.

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confidence: 88%

Detection of complete and partial chromosome gains and losses by comparative genomic in situ hybridization

et al. 1993

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“…Some information about the placement of a group of XY homologous markers in Xq21 had been derived from fluorescent in situ hybridization studies, and other ordering information had been inferred using a panel of deletion breakpoint hybrids, derived primarily from DNA of choroideremia patients (Page et al 1984;Geldwerth et al 1985;Koenig et al 1985;Philippe et al 1993). From such data, successive bins were found to include sY73 (DXYS1) and sY20 (DXYS42); sY24 (DXYS5); DXS214; and sY48 (DXYS12).…”

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confidence: 99%

“…The sex chromosomes would then have diverged somewhat, with the divergence maintained by the absence of chiasmata in this region during male meiosis. Based on the initial common probe content (Page et al 1984;Geldwerth et al 1985;Koenig et al 1985), the physical map of the Y Jones et al 1994), and now the physical map of the X, Figure 3 shows a schematic of the possible course of a potential mechanism for the divergence of X and Y in the region. The presence of the XY homology region solely on the X chromosome of apes indicates its origin as X-specific on the homonid ancestor of apes and humans (Fig.…”

Section: Evolution and Possible Gene Content Of The Xy Homology Regionmentioning

confidence: 99%

Evolutionary Features of the 4-Mb Xq21.3 XY Homology Region Revealed by a Map at 60-kb Resolution

Mumm

Molini²,

Terrell³

et al. 1997

Genome Res.

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Forty-three yeast artificial chromosomes (YACs) from the X chromosome have been overlapped across the 4-Mb Xq21.3 region, which is homologous to a segment in Yp11.1. The region is formatted to 60-kb resolution with 57 STSs and is merged at its edges with contigs specific for X. This allows a direct comparison of marker orders and distances on X and Y. In addition to some sequence variation and possible differences in marker order, two larger evolutionary divergencies between the X and Y homologs were revealed: (1) The X homolog is interrupted by a small X-specific region detected by a 3-kb plasmid probe for locus DXS214. An STS was developed from one end of the probe, but the sequence at the other end was highly homologous to an L1 repetitive element. This suggests that the interpolation of the X-specific segment may have involved an L1-mediated event. (2) A 250-kb portion containing DXYS1 is several megabases away from the rest of the homologous DNA on the Y but is contiguous with the remainder of the homologous region on X. Marker orders are consistent with the origin of the Y-specific 250-kb region in a paracentric inversion after the initial transfer of X DNA to the Y chromosome.[All sequence data for the STSs are in the Genome Database and on the Washington University web site at http://genome.wustl.edu/cgm/cgm.html.]In addition to several smaller regions , three major regions of homology are shared by the human X and Y chromosomes ( Fig.1). Two of them comprise the pseudoautosomal regions at the tips of the p and q arms, respectively 2.5 and 0.35 Mb in length. The other homologous region, in Xq21.3 and Yp11.1 Vollrath et al. 1992; Affara and FergusonSmith 1994), differs from the pseudoautosomal segments in several respects. First, it is more extensive, on the order of 4 Mb. Second, unlike the pseudoautosomal portions, the homologous X and Y segments are not thought to pair during meiosis. In the chimpanzee and lower vertebrates, this region only exists on the X chromosome (Page et al. 1984;Geldwerth et al. 1985;Koenig et al. 1985;Affara and Ferguson-Smith 1994). Hence, the XY homology region is unique to humans and presumably arose by translocation of the region from the X to the Y chromosome relatively recently on the evolutionary time-scale.A clone map of the XY homology region on both X and Y can help to determine features of the evolution of the sex chromosomes and to initiate a comparison of their genetic content. Most of the euchromatic region of the human Y chromosome has been cloned in yeast artificial chromosomes (YACs) and formatted with sequence-tagged sites (STSs) Vollrath et al. 1992). A more recent map of the Y chromosome is provided by Jones et al. (1994), although marker order within the XY homology region is essentially the same as in Foote et al. (1992). On the Y chromosome, the corresponding DNA includes STSs sY20, sY21...sY52, in numerical order across a 4-Mb region, and a relatively small segment containing DXYS1, located ∼2 Mb more proximal.The homologous region on the X chromosome ha...

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“…11 and 12), the tooth enamel protein amelogenin (AMG; ref. 13), and several loci defined by anonymous DNA fragments (14,15). The homology shared by the short arm of the X chromosome and the long arm of the Y chromosome has been cited as evidence for a pericen-…”

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confidence: 99%

X/Y translocations resulting from recombination between homologous sequences on Xp and Yq.

Yen

Tsai

Wenger

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

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Several regions of sequence homology between the human X and Y chromosomes have been identified. These segments are thought to represent areas of these chromosomes that have engaged in ineiotic recombination in relatively recent evolutionary times. Normally, the X and Y chromosomes pair during mdosis and exchange DNA only within the pseudoautosomal region at the distal short arms of both chromosomes. However, it has been suggested that aberrant recombination involving other segments of high homology could be responsible for the production of X/Y translocations. We have studied four X/Y translocation patients using molecular probes detecting homologous sequences on X and Y chromosomes. In one translocation the breakpoints have been isolated and sequenced. The mapping data are consistent with the hypothesis that X/Y translocations arise by homologous recombination. The sequencing data from one translocation demonstrate this directly.The mammalian sex chromosomes are thought to have evolved from an ancestral homologous chromosome pair (1). Although sequences have been deleted, inserted, or rearranged on the sex chromosomes over time to accommodate their now specialized functions, significant sequence similarities remain between the present-day X and Y chromosomes. Sequences in the pseudoautosomal region at the terminal portions of the short arms of the sex chromosomes are identical and, during male meiosis, there is a single and obligatory X-Y crossover within this region (2). Occasionally the X-Y interchange occurs outside the pseudoautosomal region and the testis-determining factor (TDF) gene is transferred to the X chromosome resulting in an XX male phenotype (3, 4). Outside the pseudoautosomal region, homologous sequences have been found on the long arm of the X chromosome and the short arm or the proximal long arm of the Y chromosome. These regions share >95% similarity as detected by probes DXYS1, DXYS61, and others (5-10). Because some of these sequences are found only on the X chromosome of great apes, they are thought to have been generated by transposition of sequences from the X chromosome to the Y chromosome after the divergence of humans from great apes; however, recent loss of the Y homologs in great apes is also a possible explanation. In addition, several loci in the Xpter-Xp22 region were found to share 85-95% similarity with sequences in Yqll or the pericentric region of the Y chromosome. These include the genes for steroid sulfatase (STS; refs. 11 and 12), the tooth enamel protein amelogenin (AMG; ref. 13), and several loci defined by anonymous DNA fragments (14,15). The homology shared by the short arm of the X chromosome and the long arm of the Y chromosome has been cited as evidence for a pericen-

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Homologies between X and Y charomosomes detected by DNA probes: localisation and evolution

Cited by 62 publications

References 21 publications

Detection of complete and partial chromosome gains and losses by comparative genomic in situ hybridization

Detection of complete and partial chromosome gains and losses by comparative genomic in situ hybridization

Evolutionary Features of the 4-Mb Xq21.3 XY Homology Region Revealed by a Map at 60-kb Resolution

X/Y translocations resulting from recombination between homologous sequences on Xp and Yq.

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