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J Nasir

Publications and source records attributed to J Nasir.

42 records · Page 3Linked to original sources
PubMed1993

A transcription map of the region containing the Huntington disease gene.

A transcription map of the Huntington disease gene region was generated by a direct cDNA selection strategy using genomic DNA from the 4p16.3 region surrounding the D4S95 and D4S127 loci. A total of 58 cDNA fragments were obtained from cDNAs derived from fetal brain, frontal cortex, liver and bone marrow following hybridization to overlapping YACs from this region. These cDNA clones were aligned into transcription units by hybridization to specific mRNAs, by sequence overlap and by physical mapping onto overlapping YAC clones. Nine separate transcription units spanning approximately one megabase were detected by RNA hybridization. They represent a minimum number of genes in this region and do not include those genes expressed specifically in tissues not used for the hybridization. The transcription map that is provided by the cDNA segments will lead to the generation of a detailed gene map of this region.

Base Sequence↗
PubMed1992

Cloning and mapping of the alpha-adducin gene close to D4S95 and assessment of its relationship to Huntington disease.

The genetic defect underlying Huntington's disease (HD) has been mapped to 4p16.3. Refined localization using recombinant HD chromosome analysis and allelic association analyses have identified two distinct candidate regions. Using a cDNA hybrid selection procedure we have cloned the gene for alpha-adducin, a subunit of a cytoskeletal protein crucial for spectrin-actin membrane plasticity. This gene maps to the proximal 2.2 Mb candidate region within 20 kb of D4S95. Alleles of markers at this locus have been shown to exhibit significant linkage disequilibrium with HD. A 4 kb alpha-adducin transcript was identified which is abundantly expressed in the caudate nucleus, the site of major neuronal loss in HD. Sequencing of the brain alpha-adducin cDNA from two HD patients and an age-matched control did not detect any sequence alterations specific to HD. However, we identified in brain cDNA of both patients and control samples, two alternately spliced brain exons, not previously described in the erythrocyte cDNA. A 93 bp exon is inserted in frame between codon 471 and 472 while a 34 bp exon inserted within codon 621 disrupts the frame and introduces a stop codon after 11 novel amino acids. The mapping of the adducin gene adjacent to D4S95 and its pattern of expression, as well as its potential for distinct alternately spliced variants, reinforces the necessity to accurately assess the role of the expression of this gene in the pathogenesis of HD.

Amino Acid Sequence↗
PubMed1991

Co-amplification of L1 line elements with localised low copy repeats in Giemsa dark bands: implications for genome organisation.

A repeat sequence island, located at the A3 Giemsa dark band on the mouse X chromosome and consisting of 50 copies of a localised long complex repeat unit (LCRU), features an unusually high concentration of L1 LINE repeat sequences juxtaposed and inserted within the LCRU. Sequence analysis of three independent genomic clones containing L1 LINE elements juxtaposed with the LCRU demonstrates a common junction sequence at the L1/LCRU boundary, suggesting that the high concentration of L1 LINE sequences in the repeat sequence island has arisen by association of an L1 element with an LCRU followed by amplification. The LCRU target site at this common junction sequence bears no resemblance to the target site of an L1 element inserted within one LCRU, indicating there is no specific preferential target site for L1 integration. We propose that co-amplification of L1 LINE elements with localised low copy repeat families throughout the genome could have a major effect on the chromosomal distribution of L1 LINE elements.

Animals↗
PubMed1990

Unusual molecular characteristics of a repeat sequence island within a Giemsa-positive band on the mouse X chromosome.

The mouse genome contains 50 copies of a long complex repeat unit localized as a repeat sequence island to the A3 Giemsa-positive (dark) band on the mouse X chromosome. The repeat units are not tandemly arranged but are juxtaposed and inserted by unrelated sequences of high repetition. The repeat sequence island possesses two notable features that have been suggested as diagnostic features of mammalian Giemsa-positive bands. First, the repeat sequence island encompasses a 1-megabase region devoid of CpG islands; second, it features a high concentration of L1 long interspersed repeat sequences.

Animals↗