Localization of psoriasis-susceptibility locus PSORS1 to a 60-kb interval telomeric to HLA-C. (1/1933)

Recent genome scans have established the presence of a major psoriasis-susceptibility locus in the human leukocyte antigen (HLA) complex on chromosome 6p21.3. To narrow the interval for candidate gene testing, we performed a linkage-disequilibrium analysis of 339 families, with the use of 62 physically mapped microsatellite markers spanning the major histocompatibility complex (MHC). As detected by use of the transmission/disequilibrium test (TDT), individual markers yielded significant linkage disequilibrium across most of the MHC. However, the strongest evidence for marker-trait disequilibrium was found in an approximately 300-kb region extending from the MICA gene to the corneodesmosin gene. Maximum-likelihood haplotypes were constructed across the entire MHC in the original sample and across a 1.2-Mb region of the central MHC in an expanded sample containing 139 additional families. Short (two- to five-marker) haplotypes were subjected to the TDT using a "moving-window" strategy that reduced the variability of TDT P values relative to the single-locus results. Furthermore, the expanded sample yielded a sharp peak of evidence for linkage disequilibrium that spanned approximately 170 kb and that was centered 100 kb telomeric to HLA-C. The 1.2-Mb interval was further dissected by means of recombinant ancestral haplotype analysis. This analysis identified risk haplotype 1 (RH1), which is a 60-kb fragment of ancestral haplotype 57.1, on all identifiable HLA risk haplotypes. One of these haplotypes exhibits significant linkage disequilibrium with psoriasis but does not carry Cw6, which is the HLA allele most strongly associated with the disease. These results demonstrate that RH1 is highly likely to carry the disease allele at PSORS1, and they exclude HLA-C and corneodesmosin with a high degree of confidence.  (+info)

Soggy, a spermatocyte-specific gene, lies 3.8 kb upstream of and antipodal to TEAD-2, a transcription factor expressed at the beginning of mouse development. (2/1933)

Investigation of the regulatory region of mTEAD-2, a gene expressed at the beginning of mouse pre-implantation development, led to the surprising discovery of another gene only 3.8 kb upstream of mTEAD-2. Here we show that this new gene is a single copy, testis-specific gene called SOGGY: (mSgy) that produces a single, dominant mRNA approximately 1.3 kb in length. It is transcribed in the direction opposite to mTEAD-2, thus placing the regulatory elements of these two genes in close proximity. mSgy contains three methionine codons that could potentially act as translation start sites, but most mSGY protein synthesis in vitro was initiated from the first Met codon to produce a full-length protein, suggesting that mSGY normally consists of 230 amino acids (26.7 kDa). Transcription began at a cluster of nucleotides approximately 150 bp upstream of the first Met codon using a TATA-less promoter contained within the first 0.9 kb upstream. The activity of this promoter was repressed by upstream sequences between -0.9 and -2.5 kb in cells that did not express mSgy, but this repression was relieved in cells that did express mSgy. mSgy mRNA was detected in embryos only after day 15 and in adult tissues only in the developing spermatocytes of seminiferous tubules, suggesting that mSgy is a spermatocyte-specific gene. Since mTEAD-2 and mSgy were not expressed in the same cells, the mSgy/mTEAD-2 locus provides a unique paradigm for differential regulation of gene expression during mammalian development.  (+info)

Automatic detection of conserved gene clusters in multiple genomes by graph comparison and P-quasi grouping. (3/1933)

We previously reported two graph algorithms for analysis of genomic information: a graph comparison algorithm to detect locally similar regions called correlated clusters and an algorithm to find a graph feature called P-quasi complete linkage. Based on these algorithms we have developed an automatic procedure to detect conserved gene clusters and align orthologous gene orders in multiple genomes. In the first step, the graph comparison is applied to pairwise genome comparisons, where the genome is considered as a one-dimensionally connected graph with genes as its nodes, and correlated clusters of genes that share sequence similarities are identified. In the next step, the P-quasi complete linkage analysis is applied to grouping of related clusters and conserved gene clusters in multiple genomes are identified. In the last step, orthologous relations of genes are established among each conserved cluster. We analyzed 17 completely sequenced microbial genomes and obtained 2313 clusters when the completeness parameter P: was 40%. About one quarter contained at least two genes that appeared in the metabolic and regulatory pathways in the KEGG database. This collection of conserved gene clusters is used to refine and augment ortholog group tables in KEGG and also to define ortholog identifiers as an extension of EC numbers.  (+info)

High-resolution transcript map of the region spanning D12S1629 and D12S312 at chromosome 12q13: triple A syndrome-linked region. (4/1933)

For those searching for human disease-causing genes, information on the position of genes with respect to genetic markers is essential. The physical map composed of ESTs and genetic markers provides the positional information of these markers as well as the starting point of gene identification in the form of genomic clones containing exons. To facilitate the effort of identification of genes in the region spanning D12S1629 and D12S312, we constructed a high-resolution transcript map with PAC/BAC/cosmid clones. The strategy for the construction of such a map involved utilization of STSs for the screening of the large insert bacterial chromosome libraries and a chromosome 12-specific cosmid library by hybridization. The contig was constructed based on the STS contents of the clones. The resulting high-resolution transcript map of the region between P273P14/SP6 and D12S312 spans 4.4 cM from 66.8 to 71.2 cM of the Genethon genetic map and represents approximately 2.4 Mb. It was composed of 81 BAC, 45 PAC, and 91 cosmid clones with a minimal tiling path consisting of 16 BAC and 4 PAC clones. These clones are being used to sequence this part of chromosome 12. We determined the order of 135 STSs including 74 genes and ESTs in the map. Among these, 115 STSs were unambiguously ordered, resulting in one ordered marker per 21 kb. The order of keratin type II locus genes was determined. This map would greatly enhance the positional cloning effort of the responsible genes for those diseases that are linked to this region, including male germ cell tumor as well as palmoplantar keratoderma, Bothnian-type, and triple A syndrome. This transcript map was localized at human chromosome 12q13.  (+info)

Developmentally regulated excision of a 28-base-pair sequence from the Paramecium genome requires flanking DNA. (5/1933)

The micronuclear DNA of Paramecium tetraurelia is estimated to contain over 50,000 short DNA elements that are precisely removed during the formation of the transcriptionally active macronucleus. Each internal eliminated sequence (IES) is bounded by 5'-TA-3' dinucleotide repeats, a feature common to some classes of DNA transposons. We have developed an in vivo assay to analyze these highly efficient and precise DNA excision events. The microinjection of a cloned IES into mating cells results in accurately spliced products, and the transformed cells maintain the injected DNA as extrachromosomal molecules. A series of deletions flanking one side of a 28-bp IES were constructed and analyzed with the in vivo assay. Whereas 72 bp of DNA flanking the eliminated region is sufficient for excision, lengths of 31 and 18 bp result in reduced excision and removal of all wild-type sequences adjacent to the TA results in complete failure of excision. In contrast, nucleotide mutations within the middle of the 28-bp IES do not prevent excision. The results are consistent with a functional role for perfect inverted repeats flanking the IES.  (+info)

Genomic organization and the promoter region of the round-spotted pufferfish (Tetraodon fluviatilis) CDC37 gene. (6/1933)

The CDC37 gene was isolated from a round-spotted pufferfish genomic library and characterized. This gene is composed of nine exons spanning 3.5 kb. Exon 1 contains the 5'-untranslated region and exon 2 contains the putative translation initiation site. By 5'-RACE (rapid amplication of cDNA ends) and sequence analysis, we deduced the promoter region for the CDC37 gene and found that it does not contain typical TATA or CCAAT box. The 1.8 kb DNA fragment upstream of the putative transcription initiation site contains numerous potential binding sites for transcription factors including CREB, E2A, Ets-1, GATA, NF-IL6 and PEA3. When this DNA fragment was placed upstream of the chloramphenicol acetyltransferase (CAT) reporter gene and transfected into a carp CF cell line, it could drive the synthesis of CAT enzyme four times more efficiently than the promoterless pCAT-Basic did. In addition, the CDC37 gene is linked to the TYK2 gene in a tail-to-head manner with a small intergenic region of 292 bp.  (+info)

Diversity in organization and the origin of gene orders in the mitochondrial DNA molecules of the genus Saccharomyces. (7/1933)

Sequencing of the Saccharomyces cerevisiae nuclear and mitochondrial genomes provided a new background for studies on the evolution of the genomes. In this study, mitochondrial genomes of a number of Saccharomyces yeasts were mapped by restriction enzyme analysis, the orders of the genes were determined, and two of the genes were sequenced. The genome organization, i.e., the size, presence of intergenic sequences, and gene order, as well as polymorphism within the coding regions, indicate that Saccharomyces mtDNA molecules are dynamic structures and have undergone numerous changes during their evolution. Since the separation and sexual isolation of different yeast lineages, the coding parts have been accumulating point mutations, presumably in a linear manner with the passage of time. However, the accumulation of other changes may not have been a simple function of time. Larger mtDNA molecules belonging to Saccharomyces sensu stricto yeasts have acquired extensive intergenic sequences, including guanosine-cytosine-rich clusters, and apparently have rearranged the gene order at higher rates than smaller mtDNAs belonging to the Saccharomyces sensu lato yeasts. While within the sensu stricto group transposition has been a predominant mechanism for the creation of novel gene orders, the sensu lato yeasts could have used both transposition- and inversion-based mechanisms.  (+info)

Nucleotide variation at the yellow gene region is not reduced in Drosophila subobscura: a study in relation to chromosomal polymorphism. (8/1933)

In contrast to Drosophila melanogaster and Drosophila simulans, the yellow (y) gene region of Drosophila subobscura is not located in a region with a strong reduction in recombination. In addition, this gene maps very close to the breakpoints of different inversions that segregate as polymorphic in natural populations of D. subobscura. Therefore, levels of variation at the y gene region in this species relative to those found in D. melanogaster and D. simulans may be affected not only by the change in the recombinational environment, but also by the presence of inversion polymorphism. To further investigate these aspects, an approximately 5.4-kb region of the A (=X) chromosome including the y gene was sequenced in 25 lines of D. subobscura and in the closely related species Drosophila madeirensis and Drosophila guanche. The D. subobscura lines studied differed in their A-chromosomal arrangements, A(st), A(2), and A(1). Unlike in D. melanogaster and D. simulans, levels of variation at the y gene region of D. subobscura are not reduced relative to those found at other genomic regions in the same species (rp49, Acp70A, and Acph-1). This result supports the effect of the change in the recombinational environment of a particular gene on the level of neutral variation. In addition, nucleotide variation is affected by chromosomal polymorphism. A strong genetic differentiation is detected between the A(1) arrangement and either A(st) or A(2), but not between A(st) and A(2). This result is consistent with the location of the y gene relative to the breakpoints of inversions A(1) and A(2). In addition, the pattern of nucleotide polymorphism in A(st)+A(2) and A(1) seems to point out that variation at the y gene region within these chromosomal classes is in the phase transient to equilibrium. The estimated ages of these arrangements assuming a star genealogy indicate that their origin cannot predate the D. madeirensis split. Therefore, the present results are consistent with a chromosomal phylogeny where Am(1), which is an arrangement present in D. madeirensis but absent in current populations of D. subobscura, would be the ancestral arrangement.  (+info)