genomic DNA

About: genomic DNA is a research topic. Over the lifetime, 15046 publications have been published within this topic receiving 663636 citations. The topic is also known as: genomic deoxyribonucleic acid & gDNA.

Detection of DNA sequence polymorphisms by enzymatic amplification and direct genomic sequencing.

Abstract: The discovery of RFLPs and their utilization as genetic markers has revolutionized research in human molecular genetics However, only a fraction of the DNA sequence polymorphisms in the human genome affect the length of a restriction fragment and hence result in an RFLP Polymorphisms that are not detected as RFLPs are typically passed over in the screening process though they represent a potentially important source of informative genetic markers We have used a rapid method for the detection of naturally occurring DNA sequence variations that is based on enzymatic amplification and direct sequencing of genomic DNA This approach can detect essentially all useful sequence variations within the region screened We demonstrate the feasibility of the technique by applying it to the human retinoblastoma susceptibility locus We screened 3,712 bp of genomic DNA from each of nine individuals and found four DNA sequence polymorphisms At least one of these DNA sequence polymorphisms was informative in each of three families with hereditary retinoblastoma that were not informative with any of the known RFLPs at this locus We believe that direct sequencing is a reasonable alternative to other methods of screening for DNA sequence polymorphisms and that it represents a step forward for obtaining informative markers at well-characterized loci that have been minimally informative in the past

Isolation and characterization of the human prolactin gene

Abstract: Prolactin (PRL) and growth hormone (GH) genes derive from a common ancestor and still share some sequence homologies. Their expression in the pituitary gland is regulated in opposite directions by most of the many hormones acting on them. This provides an interesting system to study sequences involved in gene expression. Using a human PRL cDNA clone as a probe, we screened a human genomic DNA library in lambda phage and isolated a single recombinant comprising the whole hPRL gene. It was characterized by restriction endonuclease mapping and cDNA hybridization, by DNA heteroduplex analysis and by nucleotide sequencing. The hPRL gene is present as a single copy per haploid genome, is approximately 10 kb long and contains four introns, three of which interrupt the coding sequence at the same locations as in the known GH and PRL genes. The origin of transcription was determined by S1 mapping on prolactinoma mRNAs. The search for direct and inverted repeats, as well as dyad symmetries was carried out in the 900-bp sequenced in the 5'-flanking region. Sequence homologies between hPRL, hGH and rPRL were derived from computer drawn matrices for these upstream regions.

Structural organization of human genomic DNA encoding the pro-opiomelanocortin peptide.

Abstract: We have isolated a human genomic DNA segment encoding the corticotropin-beta-lipotropin precursor peptide from a fetal DNA library, using previously cloned bovine cDNA for this peptide as a probe. The human genomic DNA was studied by electron microscope heteroduplex analysis and gel blotting methods, and its nucleotide sequence was determined and compared with that of cDNA corresponding to bovine pro-opiomelanocortin mRNA. From this sequence, segments of interspecies conservation and divergence, punctuated by pairs of the basic amino acid residues lysine and arginine, were identified. No noncoding intervening sequence was observed over an 830-base-pair DNA segment extending from a position near the 5' end of the structural pro-opiomelanocortin gene through the 3' terminus of the cDNA and including sequences for the component peptide hormones corticotropin and beta-lipotropin.

Molecular complementation of a genetic marker in Dictyostelium using a genomic DNA library.

Abstract: We constructed a partial Sau3A Dictyostelium genomic DNA library in a shuttle vector that replicates extrachromosomally in Dictyostelium cells. This library was used to complement Dictyostelium strain HPS400, which lacks thymidylate synthase activity and requires exogenous thymidine for growth. We have used a modified high-frequency transformation protocol that allows the introduction of the library into a sufficient number of Dictyostelium cells to select complementing plasmids. Using this approach, we have isolated a gene (Thy1) that complements the thymidine growth requirement of HPS400. The gene encodes a 1.2-kilobase RNA and the derived amino acid sequence shows no homology to thymidylate synthase, a protein highly conserved throughout evolution, or any other protein sequence in the data base examined. Thy1 provides an important selectable marker for transforming Dictyostelium cells. In addition, this work suggests that it will be possible to isolate genes that are essential for developmental processes in Dictyostelium by complementation.