Physical mapping of the human neurotensin gene (NTS) between markers D12S1444 and D12S81 on chromosome 12q21

Neurotensin (NTS) is an endogenous tridecapeptide of the central nervous system and the gastrointestinal tract of different mammalian species including human. The human gene encoding neurotensin has previously been assigned to chromosome 12 but no regional localization was available. We now confirm this assignment and place the NTS gene on the physical and cytogenetic maps. The NTS gene is located on a yeast artificial chromosome contig that contains several polymorphic markers and is close to a polymorphic marker located at 95.8 cM on the Généthon linkage map. NTS is immediately proximal to four polymorphic markers, including D12S81 (AFM102xg9) and D12S88 (AFM158yb4). Using fluorescence in situ hybridization, we map the gene cytogenetically to band 12q21.

Characterization of the cDNA and gene encoding human PDE3B, the cGIP1 isoform of the human cyclic GMP-inhibited cyclic nucleotide phosphodiesterase family

Two distinct PDE3 [cyclic GMP-inhibited cyclic nucleotide phosphodiesterase (cGI PDE)] isoforms, cGIP1 and cGIP2, have been identified. Here we report cloning of the cDNA and gene encoding human (H)cGIP1 (classified as PDE3B). The cDNA encodes a protein of 1112 amino acids (approximately 123 kDa). Northern blots indicate that its mRNA is expressed in several adipose tissue depots. The human PDE3B gene is composed of 16 exons spanning more than 114 kb and was localized to chromosome 11p15 by in situ hybridization. Exon/intron boundaries were determined, and genetic polymorphism, confirmed by single-strand conformational polymorphism of DNA from 25 healthy subjects, was demonstrated in exon 4 at nucleotide 1389 (A/G). Two polymorphic dinucleotide repeat sequences were identified in introns 5 and 12.

Integration of the cytogenetic, genetic, and physical maps of the human genome by FISH mapping of CEPH YAC clones

The physical locations on human metaphase chromosomes of over 950 yeast artificial chromosome (YAC) clones from the CEPH library have been determined by fluorescence in situ hybridization and described as fractional chromosome length relative to the terminus of the short arm. Collectively, these clones contain approximately 1 billion basepairs of human DNA, about one-third of the human genome. In addition, the locations of 337 of these clones were established in terms of cytogenetic bands for chromosomes 1-18, 20, and X. Since most clones are positive for one or more of the Généthon polymorphic STS markers with defined genetic linkage distances corresponding to their physical locations, these data facilitate the integration of the cytogenetic, genetic, and physical maps of the human genome. Use of these mapping data in conjunction with public database information on CEPH YACs greatly facilitates the identification of YACs or polymorphic markers at specific locations in the genome.

Localization of the human achaete-scute homolog gene (ASCL1) distal to phenylalanine hydroxylase (PAH) and proximal to tumor rejection antigen (TRA1) on chromosome 12q22-q23

ASCL1, the human achaete-scute homolog, is a helix-loop-helix transcription factor that was previously assigned to chromosome 12 using a rodent-human somatic hybrid panel. We now placed this gene on a yeast artificial chromosome contig encompassing position 119 cM of the Généthon genetic map between the two genes phenylalanine hydroxylase (PAH) and tumor rejection antigen 1 (TRA1). We also localized ASCL1 in the 12q22-q23 cytogenetic interval by using fluorescence in situ hybridization.

The germ cell deficient locus maps to mouse chromosome 11A2-3

The autosomal recessive mouse mutation, germ cell deficient, gcd, manifests as infertility in both sexes owing to improper migration and/or proliferation of primordial germ cells during embryonic development. Mice harboring this mutation have been hypothesized to be animal models of the human syndromes, premature ovarian failure and Sertoli cell only syndrome. Since the gcd mutation arose from the insertion of over 100 kb of foreign DNA into the chromosome during a transgenic mouse experiment, fluorescent in situ hybridization with the transgene as a probe was used to determine the chromosomal position of the gcd locus. DAPI chromosomal banding in conjunction with double labeling with the alpha 1(I) collagen gene revealed that the gcd locus is situated on mouse Chromosome (Chr) 11A2-3. Two candidate genes, Lif and Oncostatin M, map near the gcd locus; however, Southern blot hybridization analysis revealed no gross rearrangements in these genes in gcd mice. The chromosomal position of the gcd locus will prove valuable in the search for other candidate genes as well as a landmark for positional cloning experiments.

A second-generation YAC contig map of human chromosome 12

Human chromosome 12 constitutes approximately 4.5% of the human genome and has an estimated size of 135 million base pairs (Mb). We have started to construct a high-resolution physical map of chromosome 12 as overlapping yeast artificial chromosomes (YACs), using as a foundation the first-generation physical map of this chromosome covers nearly 102 Mb of DNA and includes 426 highly polymorphic, monomorphic and gene-based markers. We also mapped 119 of the YACs, most of which are part of the physical map, by cytogenetic methods. Thus the map integrates genetic, physical and cytogenetic data and provides information about the organization of this chromosome and will help in the localization and cloning of disease-related genes. The strategy used here to generate the chromosome-12 map could be applied for the rapid construction of physical and expression maps for other human chromosomes.

Multicolor FISH with a telomere repeat and Sry sequences shows that Sxr (Sex reversal) in the mouse is a new type of chromosome rearrangement

XYSxr (Sex reversal) mice carry a Y chromosome in which the chromatin (including Sry, the gene for testis determination) that normally resides on the short arm is duplicated and the second copy is relocated to the distal end of the long arm. Multicolor in situ hybridization to mitotic chromosomes of XYSxr males using probes for the telomere repeat sequence (TTAGGG)n and Sry shows that the rearranged chromatin is located distal to the telomeric signal. This suggests that the rearrangement arose from a recombination event involving the distal Y telomere sequences, i.e., within the telomere, a structure historically assumed to be incapable of participating in chromosome rearrangements.