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PubMed2000

Sex chromosome evolution in fish: the formation of the neo-Y chromosome in Eigenmannia (Gymnotiformes).

Chromosomes of a species of Eigenmannia presenting a X1X1X2X2:X1X2Y sex chromosome system, resulting from a Y-autosome Robertsonian translocation, were analyzed using the C-banding technique, chromomycin A3 (CMA3) and mithramycin (MM) staining and in situ digestion by the restriction endonuclease AluI. A comparison of the metacentric Y chromosome of males with the corresponding acrocentrics in females indicated that a C-band-positive, CMA3/MM-fluorescent and AluI digestion-resistant region had been lost during the process of translocation, resulting in a diminution of heterochromatin in the males. It is hypothesized that the presence of a smaller amount of G + C-rich heterochromatin in the sex chromosomes of the heteromorphic sex when compared with the homomorphic sex may be associated with the sex determination mechanism in this species and may be a more widely occurring phenomenon in fish with differentiated sex chromosomes than was initially thought.

Animals↗
PubMed1997

Y chromosome polymorphisms in native American and Siberian populations: identification of native American Y chromosome haplotypes.

We have initiated a study of ancient male migrations from Siberia to the Americas using Y chromosome polymorphisms. The first polymorphism examined, a C-->T transition at nucleotide position 181 of the DYS199 locus, was previously reported only in Native American populations. To investigate the origin of this DYS199 polymorphism, we screened Y chromosomes from a number of Siberian, Asian, and Native American populations for this and other markers. This survey detected the T allele in all five Native American populations studied at an average frequency of 61%, and in two of nine native Siberian populations, the Siberian Eskimo (21%) and the Chukchi (17%). This finding suggested that the DYS199 T allele may have originated in Beringia and was then spread throughout the New World by the founding populations of the major subgroups of modern Native Americans. We further characterized Native American Y chromosome variation by analyzing two additional Y chromosome polymorphisms, the DYS287 Y Alu polymorphic (YAP) element insertion and a YAP-associated A-->G transition at DYS271, both commonly found in Africans. We found neither African allele associated with the DYS199 T allele in any of the Native American or native Siberian populations. However, we did find DYS287 YAP+ individuals who harbored the DYS199 C allele in one Native American population, the Mixe, and in one Asian group, the Tibetans. A correlation of these Y chromosome alleles in Native Americans with those of the DYS1 locus, as detected by the p49a/p49f (p49a,f) probes on TaqI-digested genomic DNA, revealed a complete association of DYS1 alleles (p49a,f haplotypes) 13, 18, 66, 67 and 69 with the DYS199 T allele, while DYS1 alleles 8 and 63 were associated with both the DYS199 C and T allele.

Asia↗
PubMed1984

Philadelphia chromosomal breakpoints are clustered within a limited region, bcr, on chromosome 22.

We have identified and molecularly cloned 46 kb of human DNA from chromosome 22 using a probe specific for the Philadelphia (Ph') translocation breakpoint domain of one chronic myelocytic leukemia (CML) patient. The DNAs of 19 CML patients were examined for rearrangements on chromosome 22 with probes isolated from this cloned region. In 17 patients, chromosomal breakpoints were found within a limited region of up to 5.8 kb, for which we propose the term "breakpoint cluster region" (bcr). The two patients having no rearrangements within bcr lacked the Ph' chromosome. The highly specific presence of a chromosomal breakpoint within bcr in Ph'-positive CML patients strongly suggests the involvement of bcr in this type of leukemia.

Bacterial Proteins↗
PubMed1992

Integration of human alpha-satellite DNA into simian chromosomes: centromere protein binding and disruption of normal chromosome segregation.

Centromeres of mammalian and other complex eukaryotic chromosomes are dominated by one or more classes of satellite DNA. To test the hypothesis that alpha-satellite DNA, the major centromeric satellite of primate chromosomes, is involved in centromere structure and/or function, human alpha-satellite DNA was introduced into African green monkey (AGM) cells. Centromere protein binding was apparent at the sites of integrated human alpha-satellite DNA. In the presence of an AGM centromere on the same chromosome, human alpha-satellite was associated with bridges between the separating sets of chromatids at anaphase and an increased number of lagging chromosomes at metaphase, both features consistent with the integrated alpha-satellite disrupting normal chromosome segregation. These experiments suggest that alpha-satellite DNA provides the primary sequence information for centromere protein binding and for at least some functional aspect(s) of a mammalian centromere, playing a role either in kinetochore formation or in sister chromatid apposition.

Animals↗
PubMed1992

Detection of individual human chromosomes by chromosome in situ suppression hybridization using PCR-amplified bacteriophage library probes.

We used the polymerase chain reaction (PCR) to prepare chromosome-specific probes from the bacteriophage lambda library LAO1NS01, prepared at the Los Alamos National Laboratory from flow sorted human chromosome 1. By using oligonucleotide primers flanking the EcoRI insertion site of the Charon 21A vector, we were able to amplify the human sequences preferentially in the library up to 9.1 kb (maximum insert size). The product of the PCR reaction was nick translated with incorporation of biotinylated residues and used with fluorescence in situ hybridization to observe metaphase chromosomes by fluorescence microscopy. This technique allows for a relatively easy method for preparation of chromosome-specific library probes for "chromosome painting." The quality of the results obtained by this method compares favorably to those obtained by using bulk-purified library inserts. This method offers potential advantages in terms of cost and ease of use.

Bacteriophage lambda↗
PubMed1996

Detection of neocarzinostatin-induced translocations in human sperm chromosomes using fluorescence in situ hybridization of chromosome 2.

Mature sperm and late spermatid are known to be sensitive stages to clastogens in mammalian spermatogenesis. Certain types of chromosomal damage induced in these stages will pass to successive generations as heritable translocations. In the present study, we employed whole chromosome 2 painting with the fluorescence in situ hybridization (FISH) technique to detect the chemically induced translocations in human sperm. Mature human sperm were treated in vitro with an antitumor drug, neocarzinostatin (NCS), and fertilized in vitro with golden hamster oocytes. Sperm pronuclear chromosome slides were prepared at the first cleavage metaphase. To compare the characteristics of translocations between somatic and germ cells, human lymphocytes in peripheral blood treated with NCS in vitro were analyzed at first round metaphase after PHA-stimulation. From the analysis of translocations by whole chromosome 2 painting, frequencies of the haploid genomic translocations (FhG) were predicted for both sperm and lymphocytes. At 1.0 micrograms/ml, the actual percentages of sperm and lymphocytes with chromosome 2 translocations were almost identical (11.9% and 12.0%). At the same dose, however, the FhG of the sperm (1.15) was considerably higher than that of the lymphocytes (0.58), indicating that complex translocations having two or more rearranged sites were induced by NCS more frequently in sperm than in lymphocytes.

Animals↗
PubMed2000

Recurrent chromosome aberrations in fibrous dysplasia of the bone: a report of the CHAMP study group. CHromosomes And MorPhology.

The nosologic status of fibrous dysplasia (FD), a well-known and relatively common bone lesion, is controversial. Information collected by the CHromosomes And MorPhology (CHAMP) study group on published and unpublished cases of fibrous dysplasia shows the presence of clonal chromosome changes in at least a proportion of these lesions. The chromosome aberrations found in FD lesions have been quite variable and have included both structural and numerical changes. Two of the three cases investigated at the study group had trisomy 2 as the sole acquired anomaly. Combined with previously published data, +2 and rearrangements involving chromosome band 12p13 have each been detected in 3 of 8 cases with abnormal karyotype of 11 in which chromosomal analysis has been performed, suggesting that FD is a neoplastic lesion rather than a "dysplastic" process, as has been generally believed and as implied by its very name.

Adolescent↗
PubMed1997

Clonal chromosome aberrations with monosomy of chromosome 8 in a case of grade III chondrosarcoma.

We report cytogenetic findings in a case of grade III chondrosarcoma. Complex clonal chromosome aberrations including monosomy of chromosomes 4, 8, 13, and a consistent t(5;14)(q23;p12) were observed in all cells. There were no structural or numerical anomalies involving chromosome 12. The complexity of the chromosome aberrations reflect the advanced stage of this chondrosarcoma; we suggest a possible involvement of the EXT1 gene located on chromosome 8.

Aged↗
PubMed2000

The size difference between leishmania major friedlin chromosome one homologues is localized to sub-telomeric repeats at one chromosomal end.

Leishmania species are members of the evolutionarily ancient protozoan order Kinetoplastidae and are important human pathogens. The Leishmania genome is relatively small (approximately 34 Mbp) and is distributed among 36 chromosome pairs, ranging in size from 0.3 to 2.5 Mbp. The smallest chromosome of Leishmania major Friedlin, chrl, consists of three homologues which differ in size by approximately 29 kb. Previous sequence and Southern analyses of all three homologues reveal a conserved chromosomal core, consisting of coding and adjacent 'non-informational' sequence. Here we show the size difference between homologues is largely restricted to variation in both the number and content of several sub-telomeric repetitive elements localized on one chromosomal end. These repetitive elements also occur on other chromosomes, but some are more dispersed in the Leishmania genome than others.

Animals↗
PubMed2002

X-chromosome inactivation and the search for chromosome-wide silencers.

X-chromosome inactivation leads to divergent fates for two homologous chromosomes. Whether one X remains active or becomes silenced depends on the activity of Xist, a gene expressed only from the inactive X and whose RNA product 'paints' the X in cis. Recent work argues that Xist RNA itself is the acting agent for initiating the silencing step. Xist RNA contains separable domains for RNA localization and chromosome silencing. While no Xist RNA-interacting factors have been identified, a growing collection of chromatin alterations have been identified on the inactive X, including variant histone H2A composition and histone H3 methylation. Some or all of these changes may be critical for chromosome-wide silencing. As none of the silencing proteins identified so far is unique to X chromosome inactivation, the specificity must partly reside in Xist RNA whose spread along the X orchestrates general silencing factors for this specific task.

Animals↗
PubMed2001

Technical report: application of the Metafer2 fluorescence scanning system for the analysis of radiation-induced chromosome aberrations measured by FISH-chromosome painting.

The Metafer2 fluorescence scanning system was used for routine analysis of radiation-induced exchange aberrations measured by fluorescence in situ hybridisation (FISH) chromosome painting in human peripheral lymphocytes. The system enables a rapid and unbiased fully-automated finding and image acquisition of fluorescently stained metaphase spreads. The chromosome aberration analysis is performed interactively from stored digitised processed gallery images, presented on a screen. Appropriate software image filters are available to further improve these pictures by background correction, noise reduction and fluorescence signal enhancement. Data sets generated by computer-assisted and manual scoring of radiation-induced reciprocal translocations (2B) and total 2B (2B+related 'one-way' types) or complete dicentrics (2A) and total 2A (2A+related 'one-ways') involving painted target chromosomes 2, 3 or 4 were compared and no significant differences were found.A linear-quadratic dose-response curve for total translocations (2B+'one-ways'+complex-derived types) based on computer-assisted analysis of 27,741 metaphases with chromosome 4 painting was compared to a curve obtained earlier for manually scored translocations in a set of target chromosomes 1, 4 and 12. After extrapolation to the whole genome, no significant difference between both curves was found. From our results it can be derived that computer-assisted aberration analysis using the Metafer2 system is a reliable alternative to manual analysis. Since time saving for computer-assisted translocation analysis is about 50% compared to manual scoring, this system is highly promising for a practical application in retrospective biodosimetry of human radiation exposure.

Adult↗
PubMed1997

A new semi-automated chromosome analysis system for in vitro chromosomal aberration tests.

We have evaluated a new semi-automated chromosome analysis system, employing the Magiscan human metaphase finder, for in vitro chromosomal aberration tests. The metaphases on a slide are recognized using the main system, a metaphase finder, and their stage coordinates are transferred to the satellite system, a computerized microscope with a motorized stage, by way of a diskette. In the satellite system, a researcher analyzes one metaphase after another at high power (100 x objective) without changing the objective. The effectiveness of the system, in comparison with the manual metaphase finding and analysis, was confirmed in in vitro chromosomal aberration tests using cultured Chinese hamster cells. Structural or numerical aberrations in the cells did not affect the metaphase findings. The system reduces the time for chromosome analysis by a factor of about 4. Moreover, the system provides perfect reproducibility for analyzing procedure. It is concluded that this semi-automated system is useful in in vitro chromosomal aberration tests.

Animals↗
PubMed2000

Sex chromosome evolution in fish. II. Second occurrence of an X1X2Y sex chromosome system in Gymnotiformes.

A multiple sex chromosome system of the X1X1X2X2:X1X2Y type is reported to occur in the fish species Brachyhypopomus pinnicaudatus (Gymnotiformes, Hypopomidae), being the second occurrence of this sex chromosome system in Gymnotiformes and the fifth among Neotropical freshwater fish. The possible origin of this system was hypothesized to be a centric fusion, which occurred in an ancestral form, of two medium-sized acrocentrics, giving origin to the metacentric neo-Y. Heterochromatic DAPI-positive regions were visualized in the pericentromeric region of all the chromosomes, including the Y-chromosome. In-situ hybridization with (TTAGGG)n (all-human-telomeres probe) did not detect any telomeric interstitial regions (ITS), indicating a possible loss of terminal segments of the chromosomes involved in the neo-Y formation.

Animals↗
PubMed2002

Analysis of sex chromosomes in preimplantation genetic diagnosis for X-chromosome-linked disorders.

Preimplantation genetic diagnosis (PGD) is diagnostic tool to avoid inheritance of genetic disease by transferring unaffected embryos. Recently, PCR and FISH have been mainly applied to the diagnosis of single gene disorders and chromosomal abnormalities, respectively. Since with PGD, only a few cells are available for genetic tests, both gene and chromosomes analysis have to be obtained from the same, limited material. Cell recycling makes it possible to obtain the information on genes as well as chromosomes from the same cells. Therefore cell recycling is an acceptable strategy where in PGD targets large proportions of embryos severe chromosomal abnormalities. The responsible genes of the X-linked disorder and numerical abnormalities of sex chromosomes should be analyzed simultaneously. Gender information is definitely useful because only male affected embryos should be avoided for transfer.

Chromosomes, Human, X↗
PubMed2003

A probe generated by chromosome microdissection, useful for analyzing Y chromosome evolution in Old World monkeys.

We isolated a DNA probe, designated MMDYZ1, using a chromosome microdissection technique from the Y chromosome of the Rhesus monkey. The probe obtained from eight whole Y chromosomes shows higher specificity for the Y short arm of the Rhesus monkey, which consists totally of constitutive heterochromatin. Two microclones (MMY#3 and MMY#4) were constructed from the Y-specific primary PCR products. Sequence analysis of these two microclones revealed that both were essentially identical to each other and the sizes were 870 and 686 bp, respectively. From alignment analysis using the Genbank database of primates, the alphoid DNA has the highest affinity with the probe. However, the total composition of this probe has extremely high homology with the Y short arm of the Rhesus monkey, as demonstrated by fluorescence in-situ hybridization (FISH). Comparative FISH-mapping disclosed that this DNA-sequence cluster was located at extremely different sites on the Y chromosome in several species of the Old World monkey. Accordingly, this probe seems to be a high-quality tool, now established for the first time, for investigating Y chromosome evolution of the Old World monkey.

Animals↗
PubMed2000

Functional evidence for an ovarian cancer tumor suppressor gene on chromosome 22 by microcell-mediated chromosome transfer.

The identity of many tumor suppressor genes important in epithelial ovarian cancer tumorigenesis remains unknown. In an effort to localize a novel tumor suppressor on chromosome 22, a psv2neo tagged human chromosome 22 was transferred into the malignant epithelial ovarian cancer cell line, SKOv-3, by microcell-mediated chromosome transfer. Complete suppression of the transformed phenotype was observed in 16 of 18 individual microcell hybrid clones as evidenced by the complete abrogation of cell growth under anchorage-independent conditions. In vitro doubling times were also dramatically reduced, as was the ability to form subcutaneous tumors in CD1 nu/nu mice. Only one polymorphic marker, D22S429, segregated with decreased transformation and tumorigenic potential, suggesting that an unrecognized tumor suppressor may localize to chromosome 22q11-q12. These data provide functional support for the presence of a novel tumor suppressor locus (or loci) on chromosome 22 that is important in ovarian cancer tumorigenesis.

Animals↗
PubMed1998

Chromosomal segregation and fertility in Robertsonian chromosomal heterozygotes of the house musk shrew (Suncus murinus, Insectivora, Soricidae).

Crucial to our understanding of chromosomal variation and evolution in mammals are detailed studies of chromosomal heterozygotes, with analyses of chromosomal segregation and chromosome-derived infertility. We studied segregation and fertility in hybrids between karyotypic races of the house musk shrew Suncus murinus. These individuals were heterozygous for up to five Robertsonian fusions (Rbs) and an insertion of heterochromatin in an autosome. All variant chromosomes showed Mendelian segregation and all Rbs segregated independently of each other in the progeny of double heterozygotes. Litter size in single and even multiple Rb heterozygotes was no smaller than that in the less fertile parental strain. The effects of genetic background were more important in determining litter size than Rb heterozygosity for the shrews that we examined.

Animals↗
PubMed2000

The production and characterization of recombination between chromosome 3N of Aegilops uniaristata and chromosome 3A of wheat.

Six wheat lines with recombination between Aegilops uniaristata chromosome 3N and wheat chromosome 3A were produced. These were characterized in terms of exchange points by RFLP analysis. Chromosome 3N carries an undesirable brittle rachis gene and three of the recombinant lines had lost this character. The results also support previously published evidence of a pericentric inversion in chromosome 3N relative to the wheat homoeologous group 3 chromosomes.

Chromosomes↗