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PubMed1991

The use of fluorescence in situ hybridisation combined with premature chromosome condensation for the identification of chromosome damage.

The technique of fusing mitotic cells to interphase cells, thereby producing condensation of the chromosomes of the interphase cell (so-called 'premature chromosome condensation' or PCC), has allowed detection of the initial number of chromosome breaks and their repair following ionising radiation. However, the difficulty and tedium of scoring all the chromosome fragments, as well as the inability to readily detect exchange aberrations, has limited the use of PCC. We describe here the use of the recently developed technique of fluorescence in situ hybridisation with whole chromosome libraries to stain individual human chromosomes (also called 'chromosome painting') with the PCC's and show that this overcomes most of the limitations with the analysis of PCC's. First, by focusing on a single chromosome, scoring of breaks in the target chromosome is easy and rapid and greatly expands the radiation dose range over which the PCC technique can be used. Second, it allows the easy recognition of exchange type aberrations. A number of new applications of this technology, such as predicting the radiosensitivity of human tumours in situ, are feasible.

Cell Line↗

PubMed1991

Sex chromosome evolution: platypus gene mapping suggests that part of the human X chromosome was originally autosomal.

To investigate the evolution of the mammalian sex chromosomes, we have compared the gene content of the X chromosomes in the mammalian groups most distantly related to man (marsupials and monotremes). Previous work established that genes on the long arm of the human X chromosome are conserved on the X chromosomes in all mammals, revealing that this region was part of an ancient mammalian X chromosome. However, we now report that several genes located on the short arm of the human X chromosome are absent from the platypus X chromosome, as well as from the marsupial X chromosome. Because monotremes and marsupials diverged independently from eutherian mammals, this finding implies that the whole human X short arm region is a relatively recent addition to the X chromosome in eutherian mammals.

Animals↗

PubMed1996

Chromosome analysis by fluorescence in situ hybridization: further indications for a non-DNA-proportional involvement of single chromosomes in radiation-induced structural aberrations.

The frequencies of symmetrical complete and incomplete translocations and dicentrics induced in human lymphocytes after in vitro irradiation with 3Gy X-rays were analysed by the use of fluorescence in situ hybridization (FISH). Single whole chromosome painting (WCP) probes, specific for chromosomes 1-4, 6-10, 12, 14 and X were hybridized separately. A human pancentromeric DNA-probe was used simultaneously for unequivocal centromere detection. For both aberration types, symmetrical translocations and dicentrics, a significant deviation from a DNA-proportional distribution was found. In general, chromosomes with a higher DNA content (chromosomes 1-3, 6 and 7) were less frequently involved in the formation of symmetrical translocations and dicentrics than expected according to their DNA-content, whereas smaller chromosomes were more frequently involved. The only exception was chromosome 4, exhibiting the highest translocation frequency of all chromosomes analysed. Ratios of the yields of symmetrical translocations to the yields of dicentrics varied between 0.9 and 1.8 for the single chromosomes. The present results substantiate our previous data obtained with identical chromosomes but examined in four different triple combinations.

Chromosome Aberrations↗

PubMed1998

Chromosome healing, telomere capture and mechanisms of radiation-induced chromosome breakage.

BACKGROUND: It is generally assumed that radiation-induced chromosome breaks are the result of a cell's inability to rejoin DNA double-strand breaks (dsb), but the exact mechanisms underlying the failure to rejoin some dsb and the conversion of these lesions into chromosome breaks are poorly understood at present. It has been speculated that the conversion of dsb into chromosome breaks, following exposure of mammalian cells to ionizing radiation, may be mediated by the enzyme telomerase. Telomerase is a reverse transcriptase that has two distinct functions, to replicate pre-existing chromosome ends (telomeres) and to heal broken chromosomes by de novo addition of telomeric sequences directly on to non-telomeric DNA. Alternatively, dsb may be converted into chromosome breaks by a telomerase-independent mechanism termed telomere capture. PURPOSE: To review telomere biology and to examine the significance of chromosome healing and telomere capture mechanisms tor radiation cytogenetics. CONCLUSION: The currently available literature suggests that telomere capture may be a more frequent mechanism for stabilization of broken chromosomes in mammalian cells than telomerase-mediated chromosome healing. However, a definitive conclusion must await improvements in the resolution of molecular cytogenetic techniques to a degree which allows telomerase products to be clearly distinguishable from subtelomeric cryptic translocations indicative of telomere capture.

Animals↗

PubMed1999

Heterogeneity of Chinese hamster X chromosomes in X-ray-induced chromosomal aberrations.

PURPOSE: To study the frequencies and distribution of X-ray-induced chromosomal aberrations in different arms as well as different regions of the long arms of Chinese hamster X chromosomes by fluorescence in situ hybridization (FISH). MATERIAL AND METHODS: Female embryonic primary cells of Chinese hamster were exposed to 1 and 4 Gy X-rays during the G1 stage and metaphases were collected 20 h later with colcemid-blocking. Induced aberrations involving different arms as well as different regions of the long arm of the X chromosomes were analysed by three-colour FISH using arm-specific painting probes. Distributions of aberrations in the arms were statistically analysed by chi2-test, with the hypothesis that aberrations are proportionally distributed on the basis of their relative lengths of the arms. RESULTS: The long arms of the X chromosomes were frequently involved in breaks than was the short arm. The result of the chi2-test indicates a non-proportional distribution of breaks between the arms, while exchanges (dicentrics and translocations) involving the arms were proportionally distributed. Differential involvement of regions of the long arm, i.e. Xq1 and Xq2, in breaks was also observed. Xq21, a known common fragile site in the X chromosome, was often involved in terminal deletions. CONCLUSION: Arm-specific probes of Chinese hamster chromosomes are useful for the detailed study of X-ray-induced aberrations in the X chromosome. The heterogeneity of the Chinese hamster X chromosome in response to X-ray-induced aberrations exists not only between the short (euchromatin) and the long (heterochromatin) arms, but also between different heterochromatic regions of the long arm of the X chromosome.

Animals↗

PubMed1977

Chromosomal basis of dosage compensation in Drosophila. IX. Cellular autonomy of the faster replication of the X chromosome in haplo-X cells of Drosophila melanogaster and synchronous initiation.

[(3)H]Thymidine labeling patterns have been examined in gynandric mosaic salivary glands of drosophila melanogaster. The Ring-X stock, R(1) w(ve)/In(1)dl 49, l (1) J1 y w lz(s), was used for this purpose. 365 labeled XX2A and 40 labeled XO2A nuclei were obtained from a total of 624 nuclei in nine pairs of mosaic salivary glands. It was observed that in all but those nuclei which had DD, 1C, and 2C patterns, the X chromosome of the XO2A nuclei always had fewer sites labeled than the X chromosomes of the XX2A nuclei, for a given pattern of the autosomes in either sex. Such asynchronous labeling of the X chromosome in the XO2A (male) nuclei was observed regardless of the proportion of the XO2A cells (2.0-73.7 percent), in the mosaic glands. Moreover, while the frequency of [(3)H]thymidine labeling for all of the 39 replicating units except the two late replicating sites (3C and 11A) in the X chromosome of the XO2A nuclei, was consistently lower than in the X chromosome of the XX2A nuclei, the mean number of grains on the X chromosome was relatively (to autosomes) similar in both XX2A and XO2A cells. The results, therefore, suggest that, as in XY2A larval glands, the X chromosome in the XO2A cells also completes the replication earlier than autosomes and that the XO2A nuclei show cellular autonomy with respect to the early replication of the X chromosome, like its counterpart, RNA transcription. Absence of the asynchrony during the initial phase (DD-2C) further completes the replication earlier but that the rate of replication of its DNA is possibly faster, and (b) that there might be a common regulation with respect to the initiation of replication of different chromosomes in a genome.

Animals↗

PubMed1995

A method for the rapid generation of alpha- and classical satellite probes for human chromosome 9 by polymerase chain reaction using genomic DNA and their application to detect chromosomal alterations in interphase cells.

Fluorescence in situ hybridization (FISH) using chromosome-specific DNA probes is a technique which has recently become widely used for the analysis of chromosome alterations in interphase and metaphase cells. In this report, a polymerase chain reaction (PCR)-based method is described for simultaneously amplifying and labelling probes targeting the alpha- and classical satellite regions of chromosome 9 using either plasmid or genomic DNA. Chromosome-specific probes were generated using readily obtainable plasmid DNA and genomic DNA from a hybrid cell line containing human chromosome 9 in a hamster cell background. The utility of these probes to detect and quantify structural and numerical aberrations in interphase cells was demonstrated using a new multicolor FISH strategy by comparing the frequencies of hyperdiploidy and chromosome breakage affecting the regions targeted by the probes in interphase and metaphase human lymphocytes irradiated during culture. The irradiated cells exhibited a significantly higher frequency of tetrasomy and breakage effecting the centromeric/pericentric region of chromosome 9 as compared with non-exposed cells. In general, similar frequencies of breakage and hyperdiploidy were observed in the interphase and metaphase preparations. These results show that DNA probes for the repetitive sequences in human chromosomes can be easily generated from genomic DNA and that these probes can be effectively used to detect chromosome breakage and aneuploidy in interphase and metaphase lymphocytes in vitro.

Aneuploidy↗

PubMed1994

A small (2.4 Mb) Bacillus cereus chromosome corresponds to a conserved region of a larger (5.3 Mb) Bacillus cereus chromosome.

We have determined the sizes of the chromosomes of six Bacillus cereus strains (range 2.4-4.3 Mb) and constructed a physical map of the smallest B. cereus chromosome (2.4 Mb). This map was compared to those of the chromosomes of four B. cereus strains and one B. thuringiensis strain previously determined to be 5.4-6.3 Mb. Of more than 50 probes, 30 were localized to the same half of the larger B. cereus and B. thuringiensis chromosomes. All 30 were also present on the small chromosome. Twenty of the probes present on the other half of the larger chromosomes were either present on extrachromosomal DNA, or absent from the B. cereus strain carrying the small chromosome. We propose that the genome of B. cereus/B. thuringiensis has one constant part and another less stable part which is more easily mobilized into other genetic elements. This part of the genome is localized to one region of the chromosome and may be subject to deletions or more frequent relocations between the chromosome and episomal elements of varying sizes up to the order of megabases.

Bacillus cereus↗

PubMed1982

Measurement of transcribed human X-chromosomal DNA sequences transferred to rodent cells by chromosome-mediated gene transfer.

Transfer of genetic information can be effected by incubation of cultured eucaryotic cells with isolated metaphase chromosomes. In most cases, a resulting transformed cell contains only a fragment of a donor chromosome. The amount of transferred donor DNA has been quantified in 11 independent mouse A9 transformants by nucleic acid hybridization analysis. Each transformant had been selected for hprt (hypoxanthine phosphoribosyltransferase; EC 2.4.2.8) transfer and contained part of the human X chromosome. A labeled probe of transcribed human X-chromosomal DNA was prepared by hybridization of nick-translated unique-sequence human DNA with whole cellular RNA from a human-mouse hybrid cell line, A9/HRBC2-A, containing a single human chromosome., X. The amount of human X-chromosomal DNA in the transformants was quantitated by comparing the hybridization of this probe with transformant and A9/HRBC2-A DNAs. Two unstable transformants which had a microscopically detectable donor chromosome fragment contained 15% of the human X-chromosomal single-copy DNA. Four other unstable transformants contained 4 to 7% of human X-chromosomal DNA sequences. The transferred DNA was below the level of detection in three other unstable and in all three stable transformants. We conclude that the initial transfer event can introduce a substantial amount of genetic information but only smaller amounts of DNA are stably incorporated by integration.

Animals↗

PubMed1983

Genetic effects of chromosomal rearrangements in Chinese hamster ovary cells: expression and chromosomal assignment of TK, GALK, ACP1, ADA, and ITPA loci.

Polyethylene glycol-mediated fusion of Chinese hamster ovary (CHO) cells with mouse Cl1D cells produced interspecific somatic cell hybrids which slowly segregated CHO chromosomes. Cytogenetic and isozyme analysis of HAT- and bromodeoxyuridine-selected hybrid subclones and of members of a hybrid clone panel retaining different combinations of CHO chromosomes enabled provisional assignments of the following enzyme loci to CHO chromosomes: TK, GALK, and ACP1 to chromosome 7; TK and GALK to chromosome Z13; ACP1, ADA, and ITPA to chromosome Z8; and ADA and ITPA to chromosome Z9. These genetic markers reflect the origin of each of these Z group chromosomes and indicate the functional activity of alleles located on rearranged chromosomes. Identification of diploid electrophoretic shift mutations for ADA and ITPA was consistent with those observations. Assignment of the functional TK locus in TK+/- CHO-AT3-2 cells indicated that gene deletion may be responsible for TK hemizygosity in this subline.

Alleles↗

PubMed1997

Laser isolation of plant sex chromosomes: studies on the DNA composition of the X and Y sex chromosomes of Silene latifolia.

X and Y sex chromosomes from the dioecious plant Silene latifolia (white campion) were isolated from mitotic metaphase chromosome preparations on polyester membranes. Autosomes were ablated using an argon ion laser microbeam and isolated sex chromosomes were then recovered on excised fragments of polyester membrane. Sex chromosome associated DNA sequences were amplified using the degenerate oligonucleotide primed polymerase chain reaction (DOP-PCR) and pools of DOP-PCR products were used to investigate the genomic organization of the S. latifolia sex chromosomes. The chromosomal locations of cloned sex chromosome repeat sequences were analysed by fluorescence in situ hybridization and data complementary to laser ablation studies were obtained by genomic in situ hybridization. In combination, these studies demonstrate that the X and Y sex chromosomes of S. latifolia are of very similar DNA composition and also that they share a significant repetitive DNA content with the autosomes. The evolution of sex chromosomes in Silene is discussed and compared with that in another dioecious species, Rumex acetosa.

DNA, Plant↗

PubMed2002

Chromosome banding in amphibia. XXIII. Giant W sex chromosomes and extremely small genomes in Eleutherodactylus euphronides and Eleutherodactylus shrevei (Anura, Leptodactylidae).

Highly differentiated, heteromorphic ZZ female symbol /ZW male symbol sex chromosomes were found in the karyotypes of the neotropical leptodactylid frogs Eleutherodactylus euphronides and E. shrevei. The W chromosomes are the largest heterochromatic, female-specific chromosomes so far discovered in the class Amphibia. The analyses of the banding patterns with AT- and GC base-pair specific fluorochromes show that the constitutive heterochromatin in the giant W chromosomes consists of various categories of repetitive DNA sequences. The W chromosomes of both species are similar in size, morphology and banding patterns, whereas their Z chromosomes exhibit conspicuous differences. In the cell nuclei of female animals, the W chromosomes form very prominent chromatin bodies (W chromatin). DNA flow cytometric measurements demonstrate clear differences in the DNA content of male and female erythrocytes caused by the giant W chromosome, and also shows that these Eleutherodactylus genomes are among the smallest of all amphibian genomes. The importance of the heteromorphic ZW sex chromosomes for the study of Z-linked genes, the similarities and differences of the two karyotypes, and the significance of the exceptionally small genomes are discussed.

Animals↗

PubMed2004

Retained heterodisomy for chromosome 12 in atypical lipomatous tumors: implications for ring chromosome formation.

Atypical lipomatous tumor (ALT) is an intermediate malignant mesenchymal tumor that is characterized by supernumerary ring chromosomes and/or giant rod-shaped marker chromosomes (RGMC). Fluorescence in situ hybridization (FISH) and molecular genetic analyses have disclosed that the RGMCs always contain amplified sequences from the long arm of chromosome 12. Typically, RGMCs are the sole clonal changes and so far no deletions or other morphologic aberrations of the two normal-appearing chromosomes 12 that invariably are present have been detected. The mechanisms behind the formation of the RGMCs are unknown, but it could be hypothesized that RGMC formation is preceded by trisomy 12 or, alternatively, that ring formation of one chromosome 12 is followed by duplication of the remaining homolog. The latter scenario would always result in isodisomy for the two normal-appearing chromosomes 12, whereas the former would yield isodisomy in one-third of the cases. In order to investigate these possible mechanisms behind ring formation, we studied polymorphic loci on chromosome 12 in 14 cases of ALT showing one or more supernumerary ring chromosomes and few or no other clonal aberrations at cytogenetic analysis. The molecular genetic analyses showed that the tumor cells always retained both parental copies of chromosome 12, thus refuting the trisomy 12 and duplication hypotheses.

Adult↗

PubMed2006

Chromosome ideograms of the laboratory rat (Rattus norvegicus) based on high-resolution banding, and anchoring of the cytogenetic map to the DNA sequence by FISH in sample chromosomes.

A detailed banded ideogram representation of the rat chromosomes was constructed based on actual G-banded prometaphase chromosomes. The approach yielded 535 individual bands, a significant increase compared to previously presented ideograms. The new ideogram was adapted to the existing band nomenclature. The gene locus positions in the rat draft DNA sequence were compared to the chromosomal positions as determined by dual-color FISH, using rat (RNO) chromosomes 6 and 15 and a segment of RNO4 as sample regions. It was found that there was generally an excellent correlation in the chromosome regions tested between the relative gene position in the DNA molecules and the sub-chromosomal localization by FISH and subsequent information transfer on ideograms from measurements of chromosomal images. However, in the metacentric chromosome (RNO15), the correlation was much better in the short arm than in the long arm, suggesting that the centromeric region may distort the linear relationship between the chromosomal image and the corresponding DNA molecule.

Animals↗

PubMed1992

Mapping of five human chromosome 19 DNA markers to owl monkey chromosomes.

Hybridization of DNA from three panels of karyotypically distinct owl monkey x rodent somatic cell hybrids with human DNA probes resulted in the syntenic assignments of INSR-LDLR-TGFB1-APOE-D19S8 to owl monkey chromosome 25 of karyotype VI (2n = 49/50), INSR-LDLR-TGFB1-D19S8 to chromosome 2 of karyotype II (2n = 54), and INSR-APOE to chromosome 2 of karyotype V (2n = 46). The APOE and D19S8 loci are on adjacent regions proximal to the centromere of chromosomes 25q (K-VI) and 2p (K-II), as determined by in situ chromosomal hybridization analysis. These findings support our previous proposals on (1) the homology of these chromosomes of three owl monkey karyotypes, (2) the evolutionary derivation of chromosome 2 of karyotypes II and V as the result of two separate centric fusion events, and (3) the likelihood that owl monkey chromosome 25 (K-VI) (and its homologs) is a conserved genetic homoeolog of human chromosome 19.

Animals↗

PubMed2005

Chromosome-level homeology in paleopolyploid soybean (Glycine max) revealed through integration of genetic and chromosome maps.

Soybean has 20 chromosome pairs that are derived from at least two rounds of genomewide duplication or polyploidy events although, cytogenetically, soybean behaves like a diploid and has disomic inheritance for most loci. Genetically anchored genomic clones were used as probes for fluorescence in situ hybridization (FISH) to determine the level of postpolyploid chromosomal rearrangements and to integrate the genetic and physical maps to (1) assign linkage groups to specific chromosomes, (2) assess chromosomal structure, and (3) determine the distribution of recombination along the length of a chromosome. FISH mapping of seven putatively gene-rich BACs from linkage group L (chromosome 19) revealed that most of the genetic map correlates to the highly euchromatic long arm and that there is extensive homeology with another chromosome pair, although colinearity of some loci does appear to be disrupted. Moreover, mapping of BACs containing high-copy sequences revealed sequestration of high-copy repeats to the pericentromeric regions of this chromosome. Taken together, these data present a model of chromosome structure in a highly duplicated but diploidized eukaryote, soybean.

Chromosomes, Artificial, Bacterial↗

PubMedDate not supplied

Analysis of anaphase figures in routine histologic sections distinguishes chromosomally unstable from chromosomally stable malignancies.

A classification of neoplasms as chromosomally stable vs. unstable is of importance in assessing inherited risks but is primarily defined in cell lines where rates of instability can be directly measured. The confirmation of such a mechanistic theory in primary tissues is desirable. We examined anaphase figures in histologic slides to evaluate such criteria. The process of chromosomal instability (CIN) involves mis-segregation of chromosomes at anaphase in some or most instances, whereas chromosomally stable tumors should lack these particular abnormalities. Anaphase bridges are associated with chromosome mis-segregation and have occasionally been observed in colorectal neoplasia and in sarcomas, but have not been considered for use as a diagnostic tool. We assembled series of sarcomas, colorectal and pancreatic carcinomas belonging to two groups: those associated with or lacking chromosomal instability. Among the chromosomally stable tumors, all lacked anaphase bridges, while anaphase bridges were found in most sarcomas and carcinomas having complex genomic alterations. These results confirm a mechanistic explanation involving chromosome mis-segregation for primary human cancers having aneuploidy/CIN. A basic mechanistic distinction between neoplasms with CIN and those with minimal chromosomal changes is supported. Most importantly, our data suggest a diagnostic utility for the examination of anaphase bridges in the routine practice of pathology with a high potential to impact clinical decision-making processes regarding colorectal cancer treatment.

Anaphase↗

PubMed2002

[Structural changes of 4V chromosome of Haynaldia villosa induced by gametocidal chromosome 3C of Aegilops triuncialis].

Chromosome 3C of Aegilops triuncialis was discovered with ability to be transferred preferentially in the case of its monosomic status in wheat background, whereas, those gametes without 3C would result in chromosome structural changes including deletions and translocations. In the present study, Triticum aestivum-Haynaldia villosa substitution line 4V(4D) developed in our laboratory, was crossed to T. aestivum c.v. Norin 26-Aegilops triuncialis 3C addition line, and the hybrids F1 were then backcrossed with common wheat in order to induce structural changes of 4V. Both chromosome C-banding and genomic in situ hybridization was applied to search such chromosome variations. In this case, total genomic DNA of Haynaldia villosa was labelled by Biotin-11-dUTP as probes and total genomic DNA of Chinese Spring as the block. Moreover, several chromosome changes within common wheat such as isochromosome 1BL.1BL(B39-2) and others were also revealed. The result indicated that two translocation lines T4VL.3AS(A47-10-3) and T4VS.4DL(A47-25-4), two telocentric chromosome lines A47-7-2(4VS) and A47-32-2(4VL), and two isochromosomes including 4VS.4VS(A47-23) and 4VL.4VL(A412-5-4) were identified from BC1F2 or BC1F3. This result indicated that gametocidal chromosome 3C of Aegilop triuncialis could effectively induce structural changes of both chromosome 4V of Haynaldia villosa and chromosomes of wheat.

Chromosome Aberrations↗