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PubMed1996

Homologies between human and marmoset (Callithrix jacchus) chromosomes revealed by comparative chromosome painting.

Regions of DNA homology between human and marmoset (Callithrix jacchus) chromosomes have been demonstrated using fluorescence in situ hybridization. All 24 chromosome paints and two centromere repeat sequences from Homo sapiens (HSA) have been annealed to previously G-banded metaphase spreads of Callithrix jacchus. All human paint probes, except Y, successfully hybridized to marmoset chromosomes. Fifteen of them hybridized to one region only, seven to two regions, and paint 1 to three regions. Homologies proposed from previous banding comparisons have been confirmed for HSA 2, 4-6, 10-12, 18, 19, 21 and X and partially confirmed for HSA 1 and 3, but were not in agreement for HSA 14 and 17. Human centromere repeat sequences for X and 18 did not hybridize to marmoset chromosomes. Because, at present, there is the confusion situation of several different numbering systems for marmoset chromosomes, we propose a new simpler nomenclature based on descending order of chromosome size.

Animals↗
PubMed1991

Bivariate flow karyotyping of human chromosomes: evaluation of variation in Hoechst 33258 fluorescence, chromomycin A3 fluorescence, and relative chromosomal DNA content.

The total variation of chromosome peak positions, in bivariate distributions of Hoechst 33258 and chromomycin A3 fluorescence of 19 healthy individuals, was compared with the experimental variation, determined from 23 bivariate distributions of chromosomes prepared separately from a single cell lineage. The experimental variation in Hoechst and chromomycin fluorescence and the relative chromosomal DNA content were determined from experiments performed over several days. The additional variance contributed by time was the same as the daily variance. The accuracy by which the relative chromosomal DNA content can be calculated from bivariate peak positions was investigated. A least squares method was used to fit the distributions of relative DNA content, obtained, respectively, from mono- and bivariate flow analyses of chromosomes from the same cell lineage. In general the DNA contents match quite well, but for a few chromosomes a difference was found, statistically discernible at the 5% level. The average relative chromosomal DNA content of the chromosomes from the 19 normal individuals, calculated from bivariate peak positions, showed a linear relation with the estimates published by other investigators.

Bisbenzimidazole↗
PubMed2005

Complex chromosome 22 rearrangements in astrocytic tumors identified using microsatellite and chromosome 22 tile path array analysis.

Many studies have reported chromosome 22 as being abnormal in astrocytic tumors. In an attempt to map precisely the abnormal region or regions that potentially harbor tumor-suppressor genes or oncogenes, we constructed a chromosome 22 tile path array covering 82% of 22q with the use of 441 chromosome 22 clones. A 10-Mb whole-genome array consisting of 270 clones from all autosomes was included in the array. A total of 126 astrocytic tumors-5 diffuse astrocytomas (A), 29 anaplastic astrocytomas (AA), and 92 glioblastomas (GB)-were examined for chromosome 22 alterations both by microsatellite analysis (using 28 markers to identify allelic imbalance) and with the tile path array. The results showed that chromosome 22 alterations in astrocytic tumors could be complex. A number of tumors had a combination of deletions with and without reduplication of the retained chromosome, as well as copy number gains and amplifications. In two glioblastomas, overlapping homozygous deletions were identified that involved three genes (DEPDC5/KIAA0645, YWHAH, C22ORF24/HSN44A4A). The terminal region telomeric to the clone RP3-398C22 appeared to be the most frequently deleted region. The estimated incidence of any chromosome 22 alteration was 5% in A, 33% in AA, and 38% in GB. This study demonstrated the advantages of combining array comparative genomic hybridization and microsatellite analysis in elucidating complex genomic rearrangements in primary human tumor tissue. Supplementary material for this article can be found on the Genes, Chromosomes and Cancer website at http://www.interscience.wiley.com/jpages/1045-2257/suppmat/index.html.

Astrocytoma↗
PubMed1982

Non-random chromosomal changes involving chromosomes 6 and 7 in spontaneous rat immunocytomas.

G-banding analysis of seven Ig-secreting spontaneous rat immunocytomas showed a consistent translocation of the distal part of the q-arm of chromosome 7 to the telomeric end of chromosome 6. The breakpoints were assigned to q3.3 on chromosome 7 and q3.2 on chromosome 6. Previously, we found a similar translocation pattern in mouse plasmacytomas induced by different agents. The distal part of the q-arm of chromosome 15 was translocated to the telomeric end of chromosome 12, known to carry Igh, the immunoglobulin heavy chain cluster. The banding homologies between the chromosomes involved in the translocation in the two species suggest that a similar mechanism is responsible for plasmacytomagenesis in both. We also predict that the rat Ig heavy chain gene cluster will be located to the terminal segment of chromosome 6.

Animals↗
PubMed1989

Trisomy of chromosome 9q: specific chromosome change associated with tumorigenicity during the process of X-ray-induced neoplastic transformation in golden hamster embryo cells.

We have reported that trisomy of chromosome 7 is commonly observed in anchorage-independent clones isolated from X-irradiated golden hamster embryo cells. All 10 clones derived from different irradiated populations showed tumorigenicity when 1 x 10(7) cells were injected s.c. into nude mice (BALB/c, nu/nu). From karyotypic analysis, we found that 8 of 10 cells showed trisomy of chromosome 9. One cell line had a translocation between chromosomes 9q and 19q and trisomy of chromosome 7. The other cell line contained trisomy of chromosome 9 and a translocation between chromosomes 7q and 8q. Using Southern blot analysis, we observed no amplification of v-myc, v-Ha-ras, v-Ki-ras or N-ras-related oncogenes. Furthermore, we could not detect either an increase in expression of v-myc- and v-Ha-ras-related genes or the activation of any oncogene, by the NIH 3T3 transfection assay. Our results suggest that trisomy of chromosome 7 is insufficient for the expression of tumorigenicity and that increased dosage of chromosome 9q may play an important role in the malignant progression of X-ray-induced neoplastic transformation.

Animals↗
PubMed1996

Characterization of a chromosome-specific chimpanzee alpha satellite subset: evolutionary relationship to subsets on human chromosomes.

Alpha satellite DNA is a tandemly repeated DNA family found at the centromeres of all primate chromosomes examined. The fundamental repeat units of alpha satellite DNA are diverged 169- and 172-bp monomers, often found to be organized in chromosome-specific higher-order repeat units. The chromosomes of human (Homo sapiens (HSA)), chimpanzee (Pan troglodytes (PTR) and Pan paniscus), and gorilla (Gorilla gorilla) share a remarkable similarity and synteny. It is of interest to ask if alpha satellite arrays at centromeres of homologous chromosomes between these species are closely related (evolving in an orthologous manner) or if the evolutionary processes that homogenize and spread these arrays within and between chromosomes result in nonorthologous evolution of arrays. By using PCR primers specific for human chromosome 17-specific alpha satellite DNA, we have amplified, cloned, and characterized a chromosome-specific subset from the PTR chimpanzee genome. Hybridization both on Southern blots and in situ as well as sequence analysis show that this subset is most closely related, as expected, to sequences on HSA 17. However, in situ hybridization reveals that this subset is not found on the homologous chromosome in chimpanzee (PTR 19), but instead on PTR 12, which is homologous to HSA 2p.

Animals↗
PubMed1997

Use of the Indian muntjac idiogram to align conserved chromosomal segments in sheep and human genomes by chromosome painting.

We have hybridized all 28 chromosome-specific painting probes from the domestic sheep (Ovis aries, 2n = 54) onto metaphase chromosomes of the Indian muntjac deer (Muntiacus muntjak vaginalis, 2n = 6,7) and identified 35 conserved chromosomal segments. Results from this study show that most of the sheep acrocentric chromosomes hybridized to single regions in the Indian muntjac genome. This conserved hybridization pattern supports the concept that the large Indian muntjac chromosomes were derived from multiple tandem fusions from an ancestral deer species. Using previously reported fluorescence in situ hybridization data in which human chromosomes were hybridized onto the Indian muntjac genome, we were able to align chromosomal segments of the sheep and human genomes. Using this three-species genome alignment approach, we have identified a minimum of 42 conserved chromosomal segments between sheep and human genomes including 7 new regions not previously reported.

Animals↗
PubMed1981

The distribution of quinacrine on chromosomes as determined by X-ray microanalysis. I. Q-bands on CHO chromosomes.

The distribution of quinacrine in relation to Q-banding on CHO chromosomes has been investigated using X-ray microanalysis. Technical problems involved in this type of experiment were studied in detail. It was necessary to use a solution of quinacrine acetate in acetic acid to ensure that the only chlorine detectable in quinacrine-stained chromosomes was in the quinacrine molecule. Electron irradiation during analysis rapidly destroys quinacrine fluorescence, but the chlorine is not lost from the chromosomes, and there are several reasons for supporting that a reliable distribution of quinacrine on the chromosome can be obtained by the method. - Small variations along the chromosome in the amounts of chlorine (representing quinacrine) and of phosphorus (mainly DNA) occur. The distribution patterns for chlorine and phosphorous show a good resemblance to each other for each homologous chromosome; quinacrine fluorescence patterns (Q-bands) do not resemble chlorine distribution patterns, however. The results of this study therefore support the view that Q-bands result from the differential quenching of fluorescence along chromosomes to which the quinacrine is essentially uniformly bound, and do not reflect differential binding of quinacrine along the chromosome.

Animals↗
PubMed1984

A photographic representation of the variability in the G-banded structure of the chromosomes in the mouse karyotype. A guide to the identification of the individual chromosomes.

Analysis of the mouse chromosomes is becoming increasingly important in many fields of genetic research. It is generally considered that the mouse chromosomes are more difficult to analyse than, for example, human chromosomes which has often led to their misidentification. This article presents a guide to the correct identification of trypsin-Giemsa banded chromosomes from the mouse. The variability in the G-banded structure of each chromosome is presented pictorially together with some suggestions for their unequivocal identification. Since many of the mouse chromosomes have similar banding patterns, those chromosomes which are more frequently misidentified have been compared and contrasted. Finally a summary of the main features for the identification of each chromosome is presented.

Animals↗
PubMed1985

X chromosomal organisation and dosage compensation. In situ transcription of chromatin template activity of X chromosome hyperploids of Drosophila melanogaster.

The chromatin template activity of the polytene X chromosomal DNA was assayed by in situ transcription on the fixed polytene chromosomes using E. coli RNA polymerase holoenzyme and 3H-UTP as the monitoring substrate in various 1X2A, 2X2A and 3X2A larvae and 1X2A (+ X fragments) segmental aneuploid larvae of Drosophila melanogaster. The segmental aneuploids contained duplications for the segments 15EF-20F, 11A-20F, 8C-20F and 3E-20F of the X chromosome. Results revealed that a double dose of active loci located in the X chromosome regions 15EF-20F, 11A-20F, and 8C-20F in aneuploids synthesized nearly 40%-70% more RNA than the normal single dose of this region in the wild-type males. The activity per gene dose for the two segments in the aneuploids was also significantly higher than in their male counterpart except for the duplication dp (3E-20F), where the duplicated piece extended from the centromeric heterochromatin to include 85% of the euchromatic portion of the X chromosome. In the case of dp (3E-20F), the X chromosome was transcribed at the lower, "female" level. It may also be noted that some regions of the X chromosome when present in extra copy, especially in dp (8C-20F) influenced the template activity of the X-linked genes inside or outside the duplicated segment. Metafemales (3X2A) have 50% higher template activity of the X chromosomes than their diploid sisters. In this study, metafemales behaved as females with duplication.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Microtubules, chromosome movement, and reorientation after chromosomes are detached from the spindle by micromanipulation.

The relationship between chromosome movement and microtubules was explored by combining micromanipulation of living grasshopper spermatocytes with electron microscopy. We detached chromosomes from the spindle and placed them far out in the cytoplasm. Soon, the chromosomes began to move back toward the spindle and the cells were fixed at a chosen moment. The microtubules seen in three-dimensional reconstructions were correlated with the chromosome movement just prior to fixation. Before movement began, detached chromosomes had no kinetochore microtubules or a single one at most. Renewed movement was always accompanied by the reappearance of kinetochore microtubules; a single kinetochore microtubule appeared to suffice. Chromosome movements and kinetochore microtubule arrangements were unusual after reattachment, but their relationship was not: poleward forces, parallel to the kinetochore microtubule axis (as in normal anaphase), would explain the movement, however odd. The initial arrangement of kinetochore microtubules would have led to aberrant chromosome distribution if it persisted, but instead, reorientation to the appropriate arrangement always followed. Observations on living cells permitted us to place in sequence the kinetochore microtubule arrangements seen in fixed cells, revealing the microtubule transformations during reorientation. From the sequence of events we conclude that chromosome movement can cause reorientation to begin and that in the changes which follow, an unstable attachment of kinetochore microtubules to the spindle plays a major role.

Animals↗
PubMed1988

Chromosome 9 of Ellobius lutescens is the X chromosome.

Ellobius lutescens carries an apparently identical karyotype (2n = 17) in both sexes. On the basis of indirect evidence the unpaired chromosome 9 has been considered to represent the X chromosome of this species. We have obtained data to substantiate this view by four different techniques. After fusion of HPRT- RAG cells with E. lutescens fibroblasts we demonstrated that the enzymes HPRT and G6PD are localized on the presumptive X chromosome. By analysis of pachytene figures after silver staining we showed by electron microscopy that the single chromosome exhibits the typical features of an X chromosome in male meiosis. Hybridization of (GATA)4 and (GACA)4 oligonucleotide probes to E. lutescens DNA revealed several distinct bands in the high molecular weight range some of which appeared to be specific for the individual but not for the sex of the animal. Hybridization in situ of the (GATA)4 probe on metaphase spreads of E. lutescens did not highlight any particular chromosome segment but showed a significant deficit of these sequences in chromosome 9. These observations are discussed with respect to their bearing on X chromosome determination. Finally it is concluded that E. lutescens should be an ideal tool for testing candidate genes assumed to be involved in primary sex determination.

Animals↗
PubMed1994

The homoeologous relationships of the arms of wheat chromosomes 2A and 2D to chromosome 2B and their effect on homoeologous pairing.

Homoeologous relationships between the arms of wheat group 2 chromosomes were analysed by studying homoeologous pairing in wheat-rye hybrids. Chromosomes 2A and 2D were identified using telocentrics 2AS, 2DS or 2DL. The remaining wheat chromosomes and their arms were identified by C-banding. Wheat chromosomes in the hybrids were derived from plants which were heterozygous (Ph1/ph1b) and monotelocentric for 2AS, 2DS or 2DL. In these plants, chromosome 2B and the telocentric showed regular bivalent pairing. From the results of homoeologous pairing in wheat-rye hybrids, normal homoeologous relationships between 2AS, 2BS and 2DS, as well as between 2AL, 2BL and 2DL, were deduced. There was no evidence that wheat group 2 chromosomes were involved in evolutionary chromosome rearrangements. The existence of a pairing promoter gene on chromosome arm 2DS was supported.

Chromosomes↗
PubMed2006

Chromosome territory positioning of conserved homologous chromosomes in different primate species.

Interphase chromosomes form distinct spatial domains called chromosome territories (CTs). The position of CTs is known not to be at random and is related to chromosome size and gene density. To elucidate how CTs are arranged in primate proliferating fibroblasts and whether the radial position of CTs has been conserved during primate evolution, several specific CTs corresponding to conserved chromosomes since the Simiiformes (human 6, 12, 13, and 17 homologous CTs) have been studied in 3D preserved interphase nuclei from proliferant cells of two New World monkey species (Lagothrix lagothricha, Saimiri sciureus) and in human by three-dimensional fluorescent in situ hybridization (3D-FISH). Our results indicate that both gene-density and chromosome size influence chromosome territory arrangement in the nucleus. This influence is greater for chromosome-size than for gene-density in the three species studied. A comparison of the radial position of a given CT and its homolog in the species analyzed suggests similar CT distributions for homologous chromosomes. Our statistical analysis using the logit model shows that such homologous positionings cannot, however, be considered identical.

Animals↗
PubMed1983

Normal X chromosome induced reversion in the direction of chromosome segregation in mouse-Chinese hamster somatic cell hybrids.

The effect of a normal mouse X chromosome on the chromosome segregation of mouse-Chinese hamster somatic cell hybrids was determined by (i) producing hybrids between the mouse sarcoma line CMS4 and a microcell hybrid (mfe4) of the hamster line E36, containing a mouse X chromosome from a normal cell; (ii) isolating hybrids between CMS4 and a 6-thioguanine selected (X minus) mfe4 subpopulation; (iii) comparing the direction of segregation in the two sets of hybrids. It was found that the normal X chromosome, like the X chromosomes from two MCA-transformed sarcoma lines reported previously [9], has the ability to switch the chromosome segregation of mouse-Chinese hamster somatic cell hybrids. We conclude that the reversal in chromosome segregation is mediated by factors located on the X chromosome. We designate these genetic elements as segregation reversal genes or sr genes.

Animals↗
PubMed1989

Mapping of insertion elements IS1, IS2 and IS3 on the Escherichia coli K-12 chromosome. Role of the insertion elements in formation of Hfrs and F' factors and in rearrangement of bacterial chromosomes.

The chromosome of an Escherichia coli K-12 strain W3110 contains seven copies of insertion element IS1, 12 copies of IS2 and six copies of IS3. We determined the approximate locations of six copies of IS1 (named is1A to is1F), ten copies of IS2 (named is2A to is2J), and five copies of IS3 (named is3A to is3E) on the W3110 chromosome by plaque hybridization using the "mini-set" of the lambda phage library that includes 476 clones carrying chromosomal segments that cover the W3110 chromosome almost entirely. Cleavage maps of the W3110 chromosome and cleavage analysis of phage DNAs carrying insertion elements allowed us to assign more precise locations to most of the insertion elements and to determine their orientations. Insertion elements were distributed randomly along the W3110 chromosome in one or other orientation. Several of these were located at the same positions on the chromosome of another E. coli K-12 strain, JE5519, and they were assumed to be the original complement of insertion elements in E. coli K-12 wild-type. Locations and orientations of such insertion elements were correlated well with Hfr points of origin and with crossover points for excision of some F' factors derived from several Hfrs. Insertion elements may be involved also in rearrangement of bacterial chromosomes.

Chromosomes, Bacterial↗
PubMed1996

Cytogenetic and genetic studies of radiation-induced chromosome damage in mouse oocytes. I. Numerical and structural chromosome anomalies in metaphase II oocytes, pre- and post-implantation embryos.

The incidences of X-ray induced numerical and structural chromosome anomalies were screened in a range of developmental stages from metaphase II oocytes through to post-implantation embryos. Following 1 Gy of acute X-rays to immediately preovulatory stage oocytes, the rate of hyperploidy (chromosome gain) was found to be elevated over levels in unirradiated controls, at metaphase II, in 1-cell and 3.5 day pre-implantation embryos but not in 8.5 day post-implantation foetuses. In the latter, however, the frequency of mosiacism was significantly increased. A similar response of an increase in mosaicism but not in hyperploidy in 8.5 day post-implantation embryos was also found after irradiation of dictyate stage oocytes with 4 Gy of acute X-rays. Significantly elevated frequencies of structural chromosome anomalies were present in metaphase II oocytes and pre-implantation embryonic stages, but could not be detected in block-stained chromosome preparations from 8.5 day post-implantation foetuses. However, analysis of chromosome preparations after G-banding showed that almost 14% of 14.5 day foetuses carried a chromosome rearrangement after 1 Gy of X-rays to immediately preovulatory stage oocytes. Overall, our data indicate that the presence of radiation-induced chromosome gains are incompatible with embryonic survival but that a proportion of embryos with structural chromosome damage develop past mid-gestation. These latter embryos are therefore potentially capable of contributing to the genetic burden of the next generation.

Animals↗
PubMed1996

Cytogenetic and genetic studies of radiation-induced chromosome damage in mouse oocytes. II. Induced chromosome loss and dominant visible mutations.

The rates of X-ray induced loss of chromosome 19 in mouse oocytes were investigated in 2 experiments using a genetic complementation test. After 1 Gy of acute X-rays to immediately preovulatory stage oocytes, chromosome 19 loss was estimated to have occurred in 1.68% of cells. In comparison, after 4 Gy of acute X-rays to dictyate stage oocytes, the rate was estimated at 1.18%. The slightly higher rate of chromosome loss in the former cell stage after a smaller dose of radiation reflects the known increased radiosensitivity of mouse oocytes in the period shortly before ovulation. Comparison of the observations here for chromosome 19 with published data for chromosome 1 suggests that chromosome length is one of the principal factors in determining the initial rate of induced loss in mouse oocytes. Ten dominant visible mutations were recovered among 1674 offspring following irradiation of preovulatory oocytes, and 8 in 2025 offspring after treatment of dictyate cells. Nine dominant mutations were karyotyped, 5 of these were found to be associated with a visible chromosome rearrangement. The data obtained in the present study show that radiation-induced chromosome anomalies in female germ cells are not all filtered out by prenatal embryonic death but that a proportion has the potential to contribute to the genetic burden of the next generation.

Animals↗