Identification of the gene-richest bands in human prometaphase chromosomes

The human genome is a mosaic of long, compositionally homogeneous DNA segments, the isochores, that can be partitioned into five families, two GC-poor families (L1 and L2), representing 63% of the genome, and three GC-rich families (H1, H2 and H3), representing 24%, 7.5% and 4-5% of the genome, resp...

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Bibliographic Details
Published in:Chromosome research 1999-01, Vol.7 (5), p.379-386
Main Authors: Saccone, S, Federico, C, Solovei, I, Croquette, M F, Della Valle, G, Bernardi, G
Format: Article
Language:English
Subjects:
Base Composition
Chromosome Banding
Chromosomes, Human - genetics
Deoxyribonucleic acid
DNA
Fluorescein
Fluorescent Dyes
GC Rich Sequence
Genes
Genome, Human
Genomics
Humans
In Situ Hybridization, Fluorescence
Metaphase - genetics
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Summary:The human genome is a mosaic of long, compositionally homogeneous DNA segments, the isochores, that can be partitioned into five families, two GC-poor families (L1 and L2), representing 63% of the genome, and three GC-rich families (H1, H2 and H3), representing 24%, 7.5% and 4-5% of the genome, respectively. Gene concentration increases with increasing GC levels, reaching a level 20-fold higher in H3 compared with L isochores. In-situ hybridization of DNA from different isochore families provides, therefore, information on the chromosomal distribution of genes. Using this approach, three subsets of reverse or Giemsa-negative bands, H3+, H3* and H3-, containing large, moderate, and no detectable amounts, respectively, of the gene-richest H3 isochores were identified at a resolution of 400 bands. H3+ bands largely coincide with the most heat-denaturation-resistant bands, the chromomycin-A3-positive, DAPI-negative bands, the bands with the highest CpG island concentrations, and the earliest replicating bands. Here, we have defined the H3+ bands at a 850-band resolution, and have thus identified the human genome regions, having an average size of 4 Mb, that are endowed with the highest gene density.
ISSN:0967-3849
1573-6849
DOI:10.1023/a:1009220131225