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C D Wilde

Publications and source records attributed to C D Wilde.

At least 19 recordsLinked to original sources
PubMed1987

Conserved sequence elements in the 5' region of the Ultrabithorax transcription unit.

Clones homologous to the 5' region of the Ultrabithorax gene of Drosophila melanogaster have been isolated from D. pseudoobscura, D. funebris and Musca domestica. Regions that encode most of the Ubx protein have been sequenced in all three of these species, and the 5' upstream region has been sequenced in D. funebris to a point 1000 bases upstream of the probable mRNA start site. Here we compare these sequences with those described elsewhere for D. melanogaster. Deduced amino acid sequences of the Ubx protein show 8% (D. pseudoobscura), 15% (D. funebris) and 22% (M. domestica) divergence from D. melanogaster. However, these figures mask very different rates of evolution in different regions of the protein. A glycine-rich (;hinge') region is conserved in each of these species, although its length is variable. Comparison of D. funebris and D. melanogaster sequences in the long 5' untranslated leader region of the mRNA, and in the region immediately upstream of the start point of transcription, reveals tightly conserved elements embedded in an otherwise non-homologous sequence. These conserved elements include a 118-bp region that spans the mRNA start site, an internally repetitive (TAA)(n) region in the untranslated leader and a short repeated motif immediately upstream of the ATG codon that initiates the major open reading frame of the Ubx protein. Two other conserved elements were identified upstream of the transcription start site; both elements have structural features consistent with a role as recognition sites for regulatory proteins.

Journal Article↗
PubMed1986

Pseudogenes.

Pseudogenes are DNA sequences that bear significant homology to functional genes, yet they lack promoter sequences for their transcription or contain other mutations that preclude formation of a functional product. They appear to be a common feature of many eukaryotic genomes. Pseudogenes were first described among the 5S RNA genes of Xenopus; subsequently, they have been found for a wide range of genes, including globins, snRNAs, immunoglobulins, tubulins, and metallothionein. Some pseudogenes, like those of the beta-globins, lie within the gene cluster of their functional counterparts; they may simply have arisen by accumulation of mutations in a duplicated nonselected gene. Other pseudogenes appear to have arisen by a very different process. Characteristically, they are dispersed in the genome, lack introns, and have oligoA tracts at their 3' ends. Their structure suggests an origin from mRNAs through reverse transcription and integration into the genome. Pseudogenes have no known function. They may represent dead-end byproducts of normal cellular and evolutionary processes, yet they are also potential starting points from which new genes might evolve.

Animals↗
PubMed1983

Evolutionary history of a multigene family: an expressed human beta-tubulin gene and three processed pseudogenes.

A 3' untranslated region subclone from a human beta-tubulin cDNA clone has been used to dissect the human beta-tubulin multigene family. Four different beta-tubulin sequences were obtained. One consists of an expressed gene that yields two mRNA species of 1.8 kb and 2.6 kb as a consequence of alternative polyadenylation sites. The three remaining beta-tubulin sequences are all intronless pseudogenes, each containing a 3' poly(A) tract downstream from the poly(A) signal, and each flanked by a different short direct repeat. Two of these sequences were derived by integration into the host germ line of cDNA copies of the 1.8 kb mRNA; the third was derived from the 2.6 kb mRNA. Comparison of the functional and nonfunctional sequences suggests that the integration events took place 4, 10, and 13 million years ago. We anticipate that, in multigene families where germ-line expression occurs, a significant portion of sequences will be accounted for by pseudogenes generated via an RNA intermediate.

Amino Acid Sequence↗
PubMed1982

Diverse mechanisms in the generation of human beta-tubulin pseudogenes.

The sequence of two human beta-tubulin pseudogenes is described. One contains an intervening sequence but lacks sequences encoding the 55 N-terminal amino acids of the polypeptide chain. A second has no introns but has a polyadenylate signal and an oligoadenylate tract at its 3' end, and it is flanked by a short direct repeat. These sequences have arisen by different mechanisms, including one that probably involves reverse transcription of a processed messenger RNA and reintegration of the complementary DNA copy into the genome.

Base Sequence↗
PubMed1982

Structure of two human alpha-tubulin genes.

The ability of a chicken alpha-tubulin cDNA probe to cross-hybridize with human DNA under stringent conditions has been exploited to screen two independently constructed human genomic libraries. Nine clones were isolated, accounting for 60% of the bands observed in a whole genomic Southern blot of human DNA. Two clones were selected for further analysis by restriction mapping, orientation experiments using 3'- or 5'-specific probes, and electron microscopy of heteroduplexes. One clone, 2 alpha, contains an alpha-tubulin-specific region of 5.0 kilobases that includes three intervening sequences. The second clone, 19 alpha, contains an alpha-tubulin-specific region of 5.4 kilobases and has somewhat diverged 5' and 3' ends. Clone 19 alpha has only two intervening sequences that correspond to the first two in clone 2 alpha. However, these intervening sequences differ in size between clones 2 alpha and 19 alpha and show no detectable sequence homology. The sum of the lengths of sequences in either clone that hybridize to the cDNA probe accounts for essentially the entire length of the cDNA molecule.

Cloning, Molecular↗
PubMed1981

Structural variation among human beta-tubulin genes.

A chicken beta-tubulin cDNA probe has been used to screen two independently generated human genomic libraries. Of 13 EcoRI fragments detectable in a human genomic Southern blot experiment, 7 correspond in size to EcoRI fragments isolated from recombinant bacteriophage. The location of beta-tubulin-specific regions and the direction of transcription were determined within each cloned fragment. One clone (5 beta) contained a beta-tubulin-specific region of 6.8 kilobase pairs (kbp) that included three intervening sequences as well as a number of inverted repeat structures. The remaining clones contained beta-tubulin-specific sequences that were close to or, in two cases, substantially less than 1.9 kbp long. Because mature human beta-tubulin mRNA is approximately 1.9 kbp long, these short DNA regions cannot on their own encode a functional beta-tubulin mRNA. Analysis using 3'- and 5'-specific probes derived from the chicken cDNA clone showed the presence of both of these end regions within one truncated tubulin-like sequence. A second short tubulin-specific region failed to hybridize with a 3'-specific probe. These short sequences are therefore likely to be examples of pseudogenes that have arisen by loss of a portion of DNA essential to the production of functional human beta-tubulin mRNA.

Animals↗