A compositional map of human chromosome band Xq28.

The molar fractions of guanine plus cytosine (GC) in DNA were determined for 36 yeast artificial chromosomes (YACs) which almost completely cover human chromosome band Xq28, a terminal reverse band, corresponding to about 8 Mb of DNA. This allowed the construction of the most complete compositional map to date of a chromosomal band; three regions were observed: (i) a proximal 3.5-Mb region formed by GC-poor L and GC-rich H1 isochores; (ii) a middle 2,2-Mb region essentially formed by a GC-rich H2 isochore and a very GC-rich H3 isochore separated by a GC-poor L isochore, YACs from this region being characterized by a striking compositional heterogeneity and instability; and (iii) a distal 1.3-Mb region exclusively formed by GC-poor L isochores. Gene and CpG island concentrations increased with the GC levels of the isochores, as expected. Xq28 exemplifies a subset of reverse bands which are different from the two other subsets, namely from telomeric bands, which are characterized by specific cytogenetic properties and by the predominance of H2 and H3 isochores, and from the majority of reverse bands, which do not contain H2 and H3 isochores.

A high-resolution annotated physical map of the human chromosome 13q12-13 region containing the breast cancer susceptibility locus BRCA2.

Various types of physical mapping data were assembled by developing a set of computer programs (Integrated Mapping Package) to derive a detailed, annotated map of a 4-Mb region of human chromosome 13 that includes the BRCA2 locus. The final assembly consists of a yeast artificial chromosome (YAC) contig with 42 members spanning the 13q12-13 region and aligned contigs of 399 cosmids established by cross-hybridization between the cosmids, which were selected from a chromosome 13-specific cosmid library using inter-Alu PCR probes from the YACs. The end sequences of 60 cosmids spaced nearly evenly across the map were used to generate sequence-tagged sites (STSs), which were mapped to the YACs by PCR. A contig framework was generated by STS content mapping, and the map was assembled on this scaffold. Additional annotation was provided by 72 expressed sequences and 10 genetic markers that were positioned on the map by hybridization to cosmids.

Parvovirus B19 promoter at map unit 6 confers autonomous replication competence and erythroid specificity to adeno-associated virus 2 in primary human hematopoietic progenitor cells.

The pathogenic human parvovirus B19 is an autonomously replicating virus with a remarkable tropism for human erythroid progenitor cells. Although the target cell specificity for B19 infection has been suggested to be mediated by the erythrocyte P-antigen receptor (globoside), a number of nonerythroid cells that express this receptor are nonpermissive for B19 replication. To directly test the role of expression from the B19 promoter at map unit 6 (B19p6) in the erythroid cell specificity of B19, we constructed a recombinant adeno-associated virus 2 (AAV), in which the authentic AAV promoter at map unit 5 (AAVp5) was replaced by the B19p6 promoter. Although the wild-type (wt) AAV requires a helper virus for its optimal replication, we hypothesized that inserting the B19p6 promoter in a recombinant AAV would permit autonomous viral replication, but only in erythroid progenitor cells. In this report, we provide evidence that the B19p6 promoter is necessary and sufficient to impart autonomous replication competence and erythroid specificity to AAV in primary human hematopoietic progenitor cells. Thus, expression from the B19p6 promoter plays an important role in post-P-antigen receptor erythroid-cell specificity of parvovirus B19. The AAV-B19 hybrid vector system may also prove to be useful in potential gene therapy of human hemoglobinopathies.

Genomic structure of human microtubule-associated protein 2 (MAP-2) and characterization of additional MAP-2 isoforms.

We have determined that the gene for human microtubule-associated protein 2 (MAP-2) spans 19 exons, including 6 exons identified in this study, 1-4, 8, and 13; all six of these exons are transcribed. The alternative splicing of coding exons generates a greater diversity of MAP-2 transcripts and isoforms. The first three exons encode alternate 5' untranslated regions that can be spliced to additional untranslated sequences contained in exons 4 and 5. Exons 8 and 13 are transcribed in human fetal spinal cord, adult brain, MSN cells, and rat brain, and each exon maintains an open reading frame with both high and low molecular weight MAP-2 isoforms. Antibodies generated to synthetic peptides of exons 8 and 13 demonstrate that these exons are translated and MAP-2 isoforms containing these exons are generated.