1,721,009 research outputs found
SYNERGISTIC EFFECT OF DAPI AND THYMIDYLATE STRESS CONDITIONS ON THE INDUCTION OF COMMON FRAGILE SITES
No full textWhen supplied to human leukocytes grown in complete medium (RPMI 1640), DAPI, a nonintercalating compound specific for the AT bases of DNA, induces the appearance of three common fragile sites (CFRA) mapped at 1q42, 2q31, and 7p22. The same treatment with DAPI in a medium deficient in folic acid and thymidine (199 M) considerably increases the expression of these sites and induces the appearance of a further 16 CFRA sites at 1q24, 2p25, 4p16, 4q25, 5p15.3, 6p21.3, 6p25, 6q13, 9p24, 16p13.3, 16q23, 17q21, 18q23, 20q13.1, 21q21, and Xq28. The results point to the existence of a synergism between DAPI and thymidylate-stress culture conditions in inducing site-specific chromosome damage. The results also agree with the hypothesis that DAPI-induced CFRA sites are DNA late-replicating chromosomal areas rich in AT bases
Correction of the Wrong Name of a Fragile Site Associated to the DMD Gene
No full text[No abstract available
DAPI-INDUCIBLE COMMON FRAGILE SITES
No full textDAPI, a compound specific for the AT bases of DNA, causes gaps and breaks in three human chromosome sites, at the 1q41-1q42 interface, 2q31, and 7p22. It also induces undercondensation of a chromosome site at the 13q21-13q22 interface. The first three sites have the characteristics of 'common fragile sites' and are present as gaps and breaks on the chromosomes of seven individuals
THE EFFECT OF CAFFEINE ON DAPI-INDUCIBLE FRAGILE SITES
No full textDAPI is a non-intercalating compound which binds specifically to the AT bases of DNA. When leukocytes are grown in complete medium (RPMI 1640) DAPI induces the expression of three fragile sites on human chromosomes and if the medium is deficient in folic acid and thymidine (199M) it induces 19 fragile sites. Caffeine has been found by different authors to considerably enhance the expression of chromosome breaks which have been produced by other agents. When it is added to the complete medium after DAPI, it elicits almost all the sites that DAPI only induces in incomplete medium. When caffeine is added after DA-PI to incomplete medium, it does not significantly or unidirectionally modify the capacity of the two subjects examined to elicit fragile sites. The analysis of these results, when correlated with that of the mitotic index, reveals a different sensitivity of the two subjects to the combined DAPI-caffeine treatment. The results are quite compatible with the hypothesis that the DAPI-induced fragile sites are DNA regions which are not accurately replicated during the S phase
Longitudinal differentiation of chromosomes of Asellus aquaticus (Crust. Isop.) by in situ nick translation using restriction enzymes and DNase I
No full textAsellus aquaticus is an isopod crustacean whose chromosomes cannot be differentiated by G- or R-banding techniques. In this work, we have obtained a longitudinal differentiation of these chromosomes by in situ nick translation using restriction enzymes (HaeIII, DraI and BamHI) and DNase I digestions. The four nucleases, with different efficiencies, have produced similar labelling patterns. Staining with DAPI, Giemsa and chromomycin A(3) reveals that the DNA of the nick-translated regions is generally more resistant to extraction from the chromosome. The results obtained on the heteromorphic sex chromosome pair observed in about a quarter of the males of a natural population allow several hypotheses to be advanced on the nature and origin of chromosome dimorphism
Heterochromatin and ribosomal genes in Asellus aquaticus (Crust. Isop.)
No full textIn the present investigation chromosomal preparations of Asellus aquaticus were sequentially stained with chromomycin A3 to reveal the heterochromatic areas, hybridized in situ with rDNA probes in order to map the ribosomal genes and finally silver stained to check the transcriptional activity of these genes. The results indicate the existence of a substantial correspondence of location and size among the heterochromatic regions and the regions over which the in situ hybridization signals spread. The ribosomal genes, quite independently of their location in the secondary constriction, can be silver stained and thus appear to be transcriptionally active. The ribosomal sequences also hybridize to the entire heterochromatic areas observed on the probable Y chromosome identified in some males of a natural population. These rRNA genes are only rarely transcriptionally active
Sex chromosome differentiation revealed by comparative genomic hybridization.
No full textIn this work, genomic in-situ hybridization (GISH) was used to study the sex chromosome molecular
differentiation on chromosomes of male and female individuals of the isopod crustacean Asellus aquaticus.
As a composite hybridization probe, we contemporaneously used male and female whole genomic DNA
differently labelled in the presence of an excess of unlabelled DNA of the female homogametic sex.
The karyotype of A. aquaticus normally displays eight homomorphic chromosome pairs, but a
heteromorphic sex chromosome pair is present in about a quarter of the males of a natural population
previously identi¢ed by us.
GISH did not reveal any sex chromosome molecular differentiation on the male and female
homomorphic sex chromosome pair, and the karyotypes of these individuals were equally labelled by
the male- and female-derived probe, while the heteromorphic Y chromosome showed a differentially
labelled region only with the male-derived probe. This region evidently contains male-speci¢c sequences
but, because no similar hybridized region is observed on the male homomorphic chromosome pair, they
are probably not important for sex determination but represent a molecular differentiation acquired from
the Y chromosome.
I.F.: 3.2
Assignment of the human nebulin gene (NEB) to chromosome band 2q24.2 and of the 1(III) collagen gene (COL3A1) to chromosome band 2q32.2 by in situ hybridization; the FRA2G common fragile site lies between the two genes in the 2q31 band.
No full textIdentification and characterization of U1 small nuclear RNA genes from two crustacean isopod species
No full textFour different units containing three variants of the U1 snRNA gene have been identified in the genome of Asellus aquaticus and only one unit has been identified in the genome of Proasellus coxalis. All four identified U1 snRNA genes can be folded according to the proper secondary structure and possess the functionally useful conserved sequences. Moreover, in the 3 flanking regions, all genes present both the 3 box, a conserved sequence required for 3 processing of mature snRNA, and a polyadenylation signal which is unusual for these genes. The PCR products were used as probes in fluorescent in-situ hybridization (FISH) experiments to locate them on chromosomes of A. aquaticus and P. coxalis. I.F.: 2.9
DNA methylation, histone H3 methylation, and histone H4 acetylation in the genome of a crustacean
No full textIn this work, we used antibodies against histone H3 trimethylated at lysine 9 (H3K9m3); against histone H4 acetylated at lysines 5, 8, 12, and 16 (H4ac); and against DNA methylated at 5C cytosine (m5C) to study the presence and distribution of these markers in the genome of the isopod crustacean Asellus aquaticus. The use of these 3 antibodies to immunolabel spermatogonial metaphases yields reproducible patterns on the chromosomes of this crustacean. The X and Y chromosomes present an identical banding pattern with each of the antibodies. The heterochromatic telomeric regions and the centromeric regions are rich in H3K9m3, but depleted in m5C and H4ac. Thus, m5C does not seem to be required to stabilize the silence of these regions in this organism. I.F.: 1.9
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