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PubMed1983

Chromosome banding in Amphibia. VIII. An unusual XY/XX-sex chromosome system in Gastrotheca riobambae (Anura, Hylidae).

The mitotic and meiotic chromosomes of the marsupial frog Gastrotheca riobambae were analysed with various banding techniques. The karyotype of this species is distinguished by considerable amounts of constitutive heterochromatin and unusual, heteromorphic XY sex chromosomes. The Y chromosome is considerably larger than the X chromosome and almost completely heterochromatic. The analysis of the banding patterns obtained with GC- and AT-base-pair-specific fluorochromes shows that the constitutive heterochromatin in the Y chromosome consists of at least three different structural categories. The only nucleolus organizer region (NOR) of the karyotype is localized in the short arm of the X chromosome. This causes a sex-specific difference in the number of NOR: female animals have two NORs in diploid cells, male animals one. No cytological indications were found for the inactivation of one of the two X chromosomes in the female cells. In male meiosis, the heteromorphic sex chromosomes form a characteristic sex-bivalent by pairing their telomeres in an end-to-end arrangement. The significance of the XY/XX sex chromosomes of G. riobambae for the study of X-linked genes in Amphibia, the evolution of sex chromosomes and their specific DNA sequences, and the significance of the meiotic process of sex chromosomes are discussed.

Animals↗
PubMed1976

Comparative study of the function of polytene chromosomes in laboratory stocks of Drosophila melanogaster and the l(3)tl mutant (lethal tumorous larvae). II. Changes of banding pattern and transcriptional activity in the salivary chromosome of l(3)tl.

The salivary chromosomes of the l(3)tl mutant of D. melanogaster are considerably thicker and shorter than those of normal larvae. In most nuclei, chromosome shortening is associated with morphological changes of two types. a) The bands lose their distinctive pattern and become loose. The chromosome appears as a granular mass. In extreme cases pompon-like chromosomes arise. Most frequently male X-chromosomes undergo such changes and begin to shorten as early as in the middle of third larval instar. "Pompon" transformation is not associated with a change in the relative intensity of RNA synthesis: the ratio of silver grain number over the male X-chromosome to that over regions 61A-63F is the same in pompon-like l(3)tl chromosomes and in the male and female X-chromosomes of the normal lines. b) Shortened chromosomes occassionally retain distinct band organization and, in these cases, chromosome shortening is observed to be due to the condensation of the chromatin of many puffs and interbands resulting in the fusion of a large number of bands into "new" chromatin blocks. In regions of fused bands, transcriptional activity is decreased as compared with regions where this union does not occur. The chromosomes of l(3)tl larvae lack ecdysone-stimulated puffs and other prominent puffs. In 144-192 hour larvae, puffs can be induced by ecdysone and until 384 hours by temperature shock. The capacity of puff induction decreases with larval age.

Animals↗
PubMed1997

Chromosomal instability in a woman with infertility and two unaffected brothers: a new familial chromosomal breakage syndrome?

Repeated chromosomal analysis of peripheral blood lymphocytes and skin fibroblasts from a woman referred for amenorrhoea, streak gonads, hyperthyroidism, adiposity and elevated alpha-fetoprotein levels but no other manifestations of known chromosomal breakage syndromes demonstrated an increased spontaneous chromosomal breakage rate (ISCBR). Chromatid and chromosomal breaks were more numerous than sporadic rearrangements and dicentric chromosomes. Exposure of the cells to mitomycin C, diepoxybutane, X-rays or UV irradiation induced an increase in chromosomal and chromatid abnormalities over that in controls. A micronucleus assay demonstrated an increase in the incidence of formation of micronuclei and the population doubling time of the fibroblasts of the proposita was delayed. Chromosomal analysis was performed on lymphocytes of the parents and of five sibs of the proposita. Two brothers had chromosomal abnormalities identical to those of the patient and elevated alpha-fetoprotein levels, however, without any clinical abnormalities. The parents were affected by only a moderate ISCBR whereas two brothers and one sister were chromosomally normal. The clinical, chromosomal and biochemical findings in this family represent a novel chromosomal instability syndrome.

Adult↗
PubMed1984

Flow cytometry isolation and improved visualization of sorted mouse chromosomes. Purification of chromosomes X and ISO-1 from cell lines with Robertsonian translocations.

While analysis and sorting of human chromosomes by flow cytometry has been widely used, isolation of a pure mouse chromosome remains very difficult, since most murine chromosomes are quite similar in size. To overcome this problem, we have analysed mouse cell lines having either Robertsonian translocations or isochromosomes. The resulting metacentric chromosomes are very different in size and in morphology from normal mouse acrocentric chromosomes. These characteristics have been analysed by computer-monitored flow cytometry, facilitated by improvements in the chromosome extraction procedure. Signals characteristic of the iso-lq chromosome in cell line PCC4 azaR1, and of the normal X chromosome in the mouse strain 22CD have thus been obtained. These chromosomes have been sorted and can be easily recognized by fluorescence microscopy when collected onto serum-albumin-coated microscope slides. The technical modifications made, coupled with the existence of a great diversity of metacentric chromosomes resulting from Robertsonian translocations, should allow the purification of a number of different mouse chromosomes.

Animals↗
PubMed1994

Supernumerary ring chromosomes containing chromosome 17 sequences. A specific feature of dermatofibrosarcoma protuberans?

Mystery surrounds the mechanisms by which the uncommon cutaneous tumor dermatofibrosarcoma protuberans (DP) arises and progresses. A clue may be at hand in the form of extra abnormal chromosomes (one of three ring chromosomes per case with or without other chromosome abnormalities) seen in some 10 cases, including five cases in our experience. The specificity of the rings to DP would be enhanced if the rings were found to contain a contribution from a constant chromosome. We here report fluorescence in situ hybridization (FISH) results bearing on the chromosomal content of DP rings, together with clinical, pathologic, and cytogenetic documentation of our first two cases, which were briefly reported earlier, and three new DP cases. To dissect a translocation (in our 2nd case), we probed by FISH and discovered chromosome 17 sequences in the rings in all five DP cases. Nonfluorescent bands were seen on some rings painted with a whole chromosome 17 probe, indicating the presence in these rings of foreign chromosome sequences. The complexity of the rings was underscored by the detection in only one case of chromosome 17 centromeric sequences. The situation in DP seems to have parallels to that in well-differentiated liposarcoma, another tumor of intermediate malignancy with extra abnormal marker chromosome containing contributions from a constant chromosome and variable donors. In DP the supernumerary rings are clearly specific and significant.

Adult↗
PubMed1995

Characterization of a human chromosome 22 enriched bacterial artificial chromosome sublibrary.

Selection of chromosomal sublibraries from total human genomic libraries is critical for chromosome-based physical mapping approaches. We have previously reported a method of screening total human genomic library using flow sorted chromosomal DNA as a hybridization probe and selection of a human chromosome 22-enriched sublibrary from a total human bacterial artificial chromosome (BAC) library (Nucleic Acids Res 1995; 23: 1838-39). We describe here further details of the method of construction as well as characterization of the chromosome 22-enriched sublibrary thus constructed. Nearly 40% of the BAC clones that have been mapped by fluorescence in situ hybridization (FISH) analysis were localized to chromosome 22. By screening the sublibrary using chromosome 22-specific hybridization probes, we estimated that the sublibrary represents at least 2.5 x coverage of chromosome 22. This is in good agreement with the results from FISH mapping experiments. FISH map data also indicate that chromosome 22-specific BACs in the sublibrary represent all the subregions of chromosome 22.

Animals↗
PubMed2000

An XX/XY sex chromosome system in a fish species, Hoplias malabaricus, with a polymorphic NOR-bearing X chromosome.

Cytogenetic studies were carried out in the fish, Hoplias malabaricus, from the Parque Florestal do Rio Doce (Brazil). This population is characterized by 2n = 42 chromosomes for both males and females and an XX/XY sex chromosome system, confirmed through several banding methods. Females show 24 metacentric, 16 submetacentric and 2 subtelocentric chromosomes. Males show 24 metacentric, 17 submetacentric and 1 subtelocentric chromosomes. While the X chromosome is easily recognized (the only subtelocentric element), the Y chromosome is somewhat difficult to identify but appears to correspond to the smallest submetacentric in the male karyotype. In-situ hybridization with an 18S rDNA probe showed 10 well-labeled chromosomes, including the X chromosome. The 5S rDNA is interstitially located in a single metacentric pair independent of the 18S rDNA sites. The NOR on the X chromosome is always active and occurs adjacent to a heterochromatic distal segment on the long arm. Variations in size of the NORs and/or heterochromatic segment correspond to a polymorphic size condition observed in the X chromosome. The present results confirm the XX/XY sex chromosome system in the population analyzed as well as a new cytotype in the Hoplias malabaricus group.

Animals↗
PubMedDate not supplied

Clustering of breakpoints on chromosome 11 in human B-cell neoplasms with the t(11;14) chromosome translocation.

The t(11;14) (q13;q32) chromosome translocation has been reported in diffuse small and large cell lymphomas and in chronic lymphocytic leukaemia (B-CLL) and multiple myeloma. Because chromosome band 14q32 is involved in this translocation, as well as in the t(8;14) (q24;q32) translocation of the Burkitt tumour, interruption of the immunoglobulin heavy-chain locus was postulated for this rearrangement. We have cloned the chromosomal joinings between chromosomes 11 and 14 and also between chromosomes 14 and 18, in B-cell tumours carrying translocations involving these chromosomes, and suggested the existence of two translocated loci, bcl-1 and bcl-2, normally located on chromosomes 11 (band q13) and 18 (band q21) respectively, involved in the pathogenesis of human B-cell neoplasms. The results indicate that in the leukaemic cells from two different cases of CLL, the breakpoints on chromosome 11 are within 8 nucleotides of each other and on chromosome 14 involve the J4-DNA segment. Because we detected a 7mer-9mer signal-like sequence with a 12-base-long spacer on the normal chromosome 11, close to the breakpoint, we speculate that the t(11;14) chromosome translocation in CLL may be sequence specific and may involve the recombination system for immunoglobulin gene segment (V-D-J) joining.

B-Lymphocytes↗
PubMed2005

Sex chromosome evolution: molecular aspects of Y-chromosome degeneration in Drosophila.

Ancient Y-chromosomes of various organisms contain few active genes and an abundance of repetitive DNA. The neo-Y chromosome of Drosophila miranda is in transition from an ordinary autosome to a genetically inert Y-chromosome, while its homolog, the neo-X chromosome, is evolving partial dosage compensation. Here, I compare four large genomic regions located on the neo-sex chromosomes that contain a total of 12 homologous genes. In addition, I investigate the partial coding sequence for 56 more homologous gene pairs from the neo-sex chromosomes. Little modification has occurred on the neo-X chromosome, and genes are highly constrained at the protein level. In contrast, a diverse array of molecular changes is contributing to the observed degeneration of the neo-Y chromosome. In particular, the four large regions surveyed on the neo-Y chromosome harbor several transposable element insertions, large deletions, and a large structural rearrangement. About one-third of all neo-Y-linked genes are nonfunctional, containing either premature stop codons and/or frameshift mutations. Intact genes on the neo-Y are accumulating amino acid and unpreferred codon changes. In addition, both 5'- and 3'-flanking regions of genes and intron sequences are less constrained on the neo-Y relative to the neo-X. Despite heterogeneity in levels of dosage compensation along the neo-X chromosome of D. miranda, the neo-Y chromosome shows surprisingly uniform signs of degeneration.

Animals↗
PubMed2005

Chromosome evolution in fish: BrdU replication patterns demonstrate chromosome homeologies in two species of the genus Astyanax.

A comparison of R-banding patterns obtained by 5-bromodeoxyuridine incorporation was made between the chromosomes of two fish species of the genus Astyanax (Characiformes: Tetragonopterinae), A. altiparanae with 2n = 50 chromosomes, and A. schubarti with 2n = 36 chromosomes. The two species present the highest and the lowest chromosome numbers found in this fish genus, respectively, for which the modal chromosome number is 50. R-band homeology was detected, involving eleven chromosomes of A. schubarti and seventeen chromosomes of A. altiparanae, indicating a close chromosomal relationship between the two species, in spite of their great difference in chromosome number. A chromosome fusion in the past history of the group was hypothesized as a possible cause of the discrepant chromosome numbers of the two species.

Animals↗
PubMed1996

High-resolution FISH mapping of beta-defensin genes to river buffalo and sheep chromosomes suggests a chromosome discrepancy in ffttle standard karyotypes.

High-resolution chromosomal fluorescence in situ hybridization (FISH) and R-banding allowed the chromosomal localization of the beta-defensin gene cluster (DEFB@) to chromosome band 1p12 in the river buffalo (Bubalus bubalis, 2n = 50) and to band 24q13 in sheep (Ovis aries, 2n = 54), according to standard nomenclatures. The localizations permitted the tentative assignment of the entire bovine syntenic group U25 to these chromosomes. A FISH mapping control on cattle chromosomes confirmed the localization of DEFB@ in the homoeologous chromosome and chromosome band. Comparisons were made between river buffalo chromosome 1p and the homoeologous cattle chromosome on standard karyotypes; the results are discussed in light of gene assignments, extensive chromosome band conservation among the Bovidae, and inconsistencies in domestic cattle chromosome nomenclatures.

Animals↗
PubMedDate not supplied

Identification of marker chromosomes by in situ hybridization technique using alpha and "classical" satellite DNA probes with relative chromosomal specificity.

Nine additional marker chromosomes in children with mental retardation and congenital malformation were investigated by routine cytogenetic and in situ hybridization techniques. Five metacentric non-satellited markers and four satellited markers of unknown origin were determined by routine and banding staining. To determine the origin of small marker chromosomes a special scheme involving the sequential application of definite alphoid and "classical" satellite DNA probes with the relative chromosome specificity was employed. The probes specific to four groups of definite chromosomes (i) 1, 3, 5, 6, 7, 10, 12, 16, 19; (ii) 2, 4, 8, 9, 13, 14, 15, 18, 20, 21, 22; (iii) 1, 11, 17, X; (iiii) 9, 13, 14, 15, 21, 22, Y and in situ hybridization under low stringency conditions were used at the first stage of experiments. After the preliminary analysis and the determination of possible origin of a marker chromosome from a definite group of chromosomes the probes with a strong chromosome-specificity under high stringency conditions were used. The approach involving the application of the original collection of chromosome-specific DNA probes, including molecular markers to practically all human chromosomes [1, 2], and various conditions of hybridization provides an effective method for detecting unknown markers. Marker chromosomes investigated in this study were derivatives of chromosomes 7, 9 (two cases), 13, 14, 21 (two cases), X and Y.

Chromosome Banding↗
PubMed1978

The role of chromosomal proteins in the C-banding of Allium cepa chromosomes.

When chromosomes of Allium cepa are subjected to a C-banding procedure (incubation in saturated barium hydroxide followed by phosphate buffer at 60 degrees C for 1 h) and then treated with Giemsa stain, bands appear at the telomeres of all chromosomes. Microspectrophotometric measurements of Feulgen-DNA content, demonstrated that the C-banding procedure extracted DNA from the nuclei. Staining of banded chromosomes with several DNA-specific stains showed that this loss was differential, with the band DNA exhibiting more resistance to extraction than that of the rest of the chromosome. The C-banding procedure did not extract chromosomal proteins, however, and no difference in mass per unit length could be detected by Nomarski optics between band and interband regions. Several experiments demonstrated that chromosomal proteins play a significant role in C-banding. First, treatment of chromosomes with pronase before C-banding resulted in the elimination of differential staining with Giemsa. Furthermore, in preparations where the DNA was completely hydrolysed with hot TCA, the remaining chromosomal proteins were found to exhibit a differential affinity for Giemsa stain. Amido black staining demonstrated that total chromosomal protein was uniformly distributed after the hot TCA digestion, but the proteins localized in the telomeres had a greater affinity for the Giemsa stain than the bulk of the chromosomal proteins. When the TCA-digested chromosomes were subjected to the C-banding procedure before staining, the differential affinity of the telomeres for the Giemsa stain was lost. Thus, C-banding appears to be the result of a complex interaction between protein and DNA in which the greater resistance to extraction of the band DNA is necessary to stabilize and preserve chromatin protein which exhibits a differential affinity for Giemsa stain.

Chromosome Banding↗
PubMed1982

Insect sex chromosomes. VI. A presumptive hyperactivation of the male X chromosome in Acheta domesticus (L.).

The functional status of the X chromosome in Acheta domesticus has been analysed at the whole chromosome level on the basis of (1) 3H-thymidine autoradiography, (2) 5-BrdU/AO fluorescence microscopy (3) in vivo 5-BrdU incorporation and (4) 3H-UdR induced aberrations. The rationale of these techniques in relation to the functional aspect of the X chromosome is that the inactive X chromosome would (1) show asynchrony in DNA synthesis, (2) show differential fluorescence, (3) respond differentially to in vivo 5-BrdU treatment and (4) the active X chromosome would show aberrations when treated with 3H-Uridine. From the results, it appears that the X chromosomes in both male (XO) and female (XX) somatic cells of Acheta are euchromatic (active). Further, the single X in the male is transcriptionally as active as the two X chromosomes in the female. In other words, the single X in the male is hyperactive when compared with the single X in the female. From this it is inferred that the male X chromosome is differentially regulated in order to bring about an equalization of it's gene product(s) to that produced by both Xs in the female. Drosophila melanogaster has a comparable system of dosage compensation. Thus, Acheta is yet another insect showing evidence for an X chromosome regulatory mechanism of dosage compensation. Additionally, it is surmised that sex determination in Acheta is based on an autosomes/X chromosome balance mechanism.

Animals↗
PubMed1975

X-ray induced visible alterations in the giant chromosomes of Phryne cincta (Nematocera, Diptera): relation of radiation sensitivity to pronuclear chromosome structure.

In order to induce chromosomal rearrangements, males were exposed to x-rays and then mated to non-irradiated females. The number of each type of structural alteration was determined by examination of the polytene chromosomes of the F1 progeny. -- A comparison of the results with similar studies made on Drosophila revealed a significantly greater sensitivity in Phryne. Parallel to that an extremely high frequency of small inversions was ascertained in Phryne, and the observed ratio of inversions to translocations was the inverse of that which would be expected from purely mathematical considerations based on the lengths of the different chromosomes. These facts allow the conclusion that the paternal pronuclear chromosomes in Phryne are highly spiralized. Besides, the kinetochore-to-translocation-breakpoint distance was measured in both of the chromosomes involved in each reciprocal translocation and the differences (kinetochore-break distance differences) were registered and from them the arrangement of the chromosomes in the pronucleus of Phryne deduced. The data obtained support the assumption of an ordered, polar-field type of orientation. In Drosophila, in contrast, the comparable data showed that the pronuclear chromosomes are not spiralized and are randomly arranged (Bauer, 1939). -- These results seem to indicate that a close correlation exists between the different radiation sensitivities of Drosophila and Phryne and the different states of spiralisation and arrangements of their chromosomes in the pronucleus stage. It is hypothesized that the influence of the maternal genome on the degree of spiralization of the paternal chromosomes could account for differences in the pronuclear chromosome structure of both species.

Animals↗
PubMed1985

Optimising human chromosome separation for the production of chromosome-specific DNA libraries by flow sorting.

A number of cell lines, some containing chromosomes with distinctive heteromorphisms, have been flow karyotyped using a single laser flow sorter in an attempt to select those suitable for sorting all human chromosomes individually. Using the non-base-specific DNA stain ethidium bromide, chromosomes 3, 4, 5, and 6 form individual peaks in practically all normal subjects, while the right combination of heteromorphisms enables chromosomes 1, 2, 8, 9, 13, 16, 17, 18, 19, 20, 21, 22, and Y to be sorted separately. Two male cell lines, one containing a duplication and one a deletion of the X, produce flow karyotypes suitable for sorting chromosomes 7 and 8. The use of numerical chromosome abnormalities to enrich the sex chromosomes and the autosomes 18 and 21 is also illustrated. The DNA stain Hoechst 33258 binds preferentially to AT base pairs. Flow karyotypes produced with this fluorochrome separate some chromosomes not well separated with ethidium bromide. Chromosomes 5, 6, 8, 13, 14, 15, 17, and 20, and Y can be sorted individually with Hoechst 33258 with the right combination of heteromorphisms. Using these techniques, all human chromosomes apart from 10, 11, and 12 have been found as individual flow karyotype peaks, suitable for sorting with a high degree of purity.

Bisbenzimidazole↗
PubMed1996

Detection of chromosomal abnormalities of chromosome 12 in uterine leiomyoma using fluorescence in situ hybridization.

Fifty uterine leiomyomas were examined using conventional cytogenetic method and fluorescence in situ hybridization (FISH) for detection of chromosomal abnormalities of chromosome 12. Of the 50 tumors, nine were examined using FISH on the non-cultured samples. Two (4.0%) of 50 tumor samples examined showed chromosomal abnormalities of chromosome 12 by the conventional cytogenetic analysis. For FISH, the whole-chromosome painting probe and D12Z3 probe specific for the centromeric region were used. Of the 50 cultured samples, 10 showed structural aberrations and four showed numerical aberrations of chromosome 12 by FISH analysis. Of the nine non-cultured samples, four showed structural abnormalities of chromosome 12, all of which also showed structural abnormalities of chromosome 12 on the cultured samples. These results indicate that chromosomal abnormalities of chromosome 12 are important in the biology of at least some types of uterine leiomyoma, and that FISH is a useful complement to the conventional cytogenetic analysis in the study of solid tumors.

Chromosome Aberrations↗
PubMed2002

Analysis of chromosome conservation in Lemur catta studied by chromosome paints and BAC/PAC probes.

A panel of human chromosome painting probes and bacterial and P1 artificial chromosome (BAC/PAC) clones were used in fluorescence in situ hybridization (FISH) experiments to investigate the chromosome conservation of the ring-tailed lemur (Lemur catta, LCA) with respect to human. Whole chromosome paints specific for human chromosomes 7, 9, 11, 13, 14, 17, 18, 20, 21, and X were found to identify a single chromosome or an uninterrupted chromosomal region in LCA. A large set of partial chromosome paints and BAC/PAC probes were then used to refine the characterization of the rearrangements differentiating the two karyotypes. The results were also used to reconstruct the ancestral Lemuridae karyotype. Lemur catta, indeed, can be used as an outgroup, allowing symplesiomorphic (ancestral) rearrangements to be distinguished from apomorphic (derived) rearrangements in lemurs. Some LCA chromosomes are difficult to distinguish morphologically. The 'anchorage' of most LCA chromosomes to specific probes will contribute to the standardization of the karyotype of this species.

Animals↗