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M Ashburner

Publications and source records attributed to M Ashburner.

At least 37 records · Page 2Linked to original sources
PubMed1999

Constitutive activation of toll-mediated antifungal defense in serpin-deficient Drosophila.

The antifungal defense of Drosophila is controlled by the spaetzle/Toll/cactus gene cassette. Here, a loss-of-function mutation in the gene encoding a blood serine protease inhibitor, Spn43Ac, was shown to lead to constitutive expression of the antifungal peptide drosomycin, and this effect was mediated by the spaetzle and Toll gene products. Spaetzle was cleaved by proteolytic enzymes to its active ligand form shortly after immune challenge, and cleaved Spaetzle was constitutively present in Spn43Ac-deficient flies. Hence, Spn43Ac negatively regulates the Toll signaling pathway, and Toll does not function as a pattern recognition receptor in the Drosophila host defense.

Animals↗
PubMed1999

An exploration of the sequence of a 2.9-Mb region of the genome of Drosophila melanogaster: the Adh region.

A contiguous sequence of nearly 3 Mb from the genome of Drosophila melanogaster has been sequenced from a series of overlapping P1 and BAC clones. This region covers 69 chromosome polytene bands on chromosome arm 2L, including the genetically well-characterized "Adh region." A computational analysis of the sequence predicts 218 protein-coding genes, 11 tRNAs, and 17 transposable element sequences. At least 38 of the protein-coding genes are arranged in clusters of from 2 to 6 closely related genes, suggesting extensive tandem duplication. The gene density is one protein-coding gene every 13 kb; the transposable element density is one element every 171 kb. Of 73 genes in this region identified by genetic analysis, 49 have been located on the sequence; P-element insertions have been mapped to 43 genes. Ninety-five (44%) of the known and predicted genes match a Drosophila EST, and 144 (66%) have clear similarities to proteins in other organisms. Genes known to have mutant phenotypes are more likely to be represented in cDNA libraries, and far more likely to have products similar to proteins of other organisms, than are genes with no known mutant phenotype. Over 650 chromosome aberration breakpoints map to this chromosome region, and their nonrandom distribution on the genetic map reflects variation in gene spacing on the DNA. This is the first large-scale analysis of the genome of D. melanogaster at the sequence level. In addition to the direct results obtained, this analysis has allowed us to develop and test methods that will be needed to interpret the complete sequence of the genome of this species. Before beginning a Hunt, it is wise to ask someone what you are looking for before you begin looking for it. Milne 1926

Alcohol Dehydrogenase↗
PubMed1999

stress sensitive B encodes an adenine nucleotide translocase in Drosophila melanogaster.

Adenine nucleotide translocases (ANT) are required for the exchange of ADP and ATP across the inner mitochondrial membrane. They are essential for life, and most eukaryotes have at least two different Ant genes. Only one gene had been described from Drosophila, and this had not been characterized genetically. We show that mutations in this gene correspond to the previously described loci, sesB and l(1)9Ed. Immediately adjacent to this gene is another encoding a second ANT protein, which has 78% identity to that encoded by sesB/l(1)9Ed. These two genes are transcribed from a common promoter, and their mRNAs are produced by differential splicing. Hutter and Karch suggested that the sesB ANT gene corresponded to Hmr, a gene identified by an allele that rescues otherwise inviable interspecific hybrids between Drosophila melanogaster and its sibling species. This hypothesis is not supported by our study of the ANT genes of D. melanogaster.

Amino Acid Sequence↗
PubMed1999

[Comparison of the molecular and genetic map of the 2B6-2B7-8 of Drosophila melanogaster X-chromosome].

Molecular and genetic data were compared for the 2B6-2B7-8 region of the Drosophila melanogaster X chromosome. This region contains the dor (deep orange) and swi (single wing) genes influencing ecdysterone-dependent gene expression. Genes which had not been identified previously by genetic methods were shown to be present in this region. Two novel loci, designated a6 and b6, were characterized in detail. Both genes are expressed throughout Drosophila embryogenesis. The product of b6 has a homology with mammalian pentraxins. This is the first Drosophila gene found to contain the pentraxin motif.

Amino Acid Sequence↗
PubMed1998

Speculations on the subject of alcohol dehydrogenase and its properties in Drosophila and other flies.

The alcohol dehydrogenases (ADH) and their genes (Adh) of Drosophila have been much studied by population and evolutionary biologists. I attempt to put some of these studies into a broad adaptionist perspective, suggesting the co-evolution of this enzyme with the fleshy fruits of angiosperms and fermenting yeasts. I suggest that these events occurred at about the K/T boundary (65 million years ago) and that the typical Drosophila (as exemplified by D. melanogaster) evolved from flies unable to use fermenting substrates as breeding sites. I also hint that the ADH enzymes of other flies (e.g., the tephritid fruit flies) may have evolved independently of those of Drosophila, but from a common ancestral gene.

Alcohol Dehydrogenase↗
PubMed1998

Ecdysone pathway is required for furrow progression in the developing Drosophila eye.

In Drosophila, secretion of the steroid hormone ecdysone from the prothoracic ring gland coordinates and triggers events such as molting and metamorphosis. In the developing Drosophila compound eye, pattern formation and cell-type specification initiate at a moving boundary known as the morphogenetic furrow. We have investigated the role of ecdysone in eye development and report here that the ecdysone signaling pathway is required for progression of the morphogenetic furrow in the eye imaginal disc of Drosophila. Genetic disruption both of the ecdysone signal in vivo with the ecdysoneless1 (ecd1) mutant and of ecdysone response with a Broad-Complex mutant result in disruption of morphogenetic furrow progression. In addition, we show that ecdysone-dependent gene expression, both of a reporter of transcriptional activity of the Ecdysone Receptor and of the Z1 isoform of the Broad Complex, are localized in and close to the furrow. These results suggest that, in the morphogenetic furrow, temporal hormonal signals are integrated into genetic pathways specifying spatial pattern.

Animals↗
PubMed1997

One-hundred and five new potential Drosophila melanogaster genes revealed through STS analysis.

Complementation analysis had suggested that the Drosophila melanogaster genome contains approximately 5000 genes, but it is now generally accepted that the actual number is several times as high. We report here an analysis of 1788 anonymous sequence tagged sites (STSs) from the European Drosophila Genome Project (EDGP), totalling 463 kb. The data reveal a substantial number of previously undescribed potential genes, amounting to 6.1% of the number of Drosophila genes already in the sequence databases.

Amino Acid Sequence↗
PubMed1997

The Adh-related gene of Drosophila melanogaster is expressed as a functional dicistronic messenger RNA: multigenic transcription in higher organisms.

Essentially all eukaryotic cellular mRNAs are monocistronic, and are usually transcribed individually. Two tandemly arranged Drosophila genes, alcohol dehydrogenase (Adh) and Adh-related (Adhr), are transcribed as a dicistronic transcript. From transcripts initiated from the Adh promoter, two classes of mRNA are accumulated, one is monocistronic and encodes Adh alone, the other is dicistronic and includes the open reading frames of both Adh and Adhr. The dicistronic transcript is found in polysomes and the Adhr protein product is detected by antibody staining. We present evidence that the accumulation of the dicistronic mRNA is controlled at the level of the 3' end processing.

Alcohol Dehydrogenase↗
PubMed1997

Molecular characterization of the deep orange (dor) gene of Drosophila melanogaster.

Mutations of the dor gene of Drosophila melanogaster cause defects in different stages of development. Heterozygotes for lethal or viable dor alleles and the rearrangement T(1;2)dor(var7), which causes position effect variegation of dor, exhibit traits such as rough eyes, reduction of bristles on the thorax and scutellum and wavy wings. The dor gene was mapped to the proximal part of the 2B3-5 band or in the interband between 2B3-5 and 2B6 and localised within an interval of 5 kb on the physical map of the cloned 2B region. The 3.0-3.1 kb dor transcript was detected by Northern hybridization at all stages of development and is expressed in salivary glands of third instar larve. This RNA was not expressed in the dor mutants with insertions in the 5' part of the gene. The sequence of the 3180 bp (dor cDNA predicts a 115.3 kDa protein that contains a cysteine- and histidine-rich zinc finger-like motif CX2CX13CXHX2HX2CX2H at the C-terminus. The protein sequence reveals 23% identity to the Saccharomyces cerevisiae PEP3 protein. The most significant homology (57%) similarity and 32%, identity) between the DOR and PEP3 proteins is observed at the C-termini of the proteins.

Amino Acid Sequence↗
PubMed1997

FlyBase: a Drosophila database. The FlyBase consortium.

FlyBase is a database of genetic and molecular data concerning Drosophila. FlyBase is maintained as a relational database (in Sybase) and is made available as html documents and flat files. The scope of FlyBase includes: genes, alleles (and phenotypes), aberrations, transposons, pointers to sequence data, clones, stock lists, Drosophila workers and bibliographic references. The Encyclopedia of Drosophila is a joint effort between FlyBase and the Berkeley Drosophila Genome Project which integrates FlyBase data with those from the BDGP.

Animals↗
PubMed1997

Informatics--genome and genetic databases.

Databases for biologists are becoming increasingly important. Some of these can be regarded as 'core' resources, such as the bibliographic databases, whereas others are of greater interest to specialists. As comparative genomics develops, however, even databases limited in their scope (e.g. to a single organism) are of great interest to a wider community.

Animals↗
PubMed1997

Topological constraints on transvection between white genes within the transposing element TE35B in Drosophila melanogaster.

The transposable element TE35B carries two copies of the white (w) gene at 35B1.2 on the second chromosome. These w genes are suppressed in zeste-1 (z1) mutant background in a synapsis-dependent manner. Single-copy derivatives of the original TE35B stock give red eyes when heterozygous, but zeste eyes when homozygous. TE35B derivatives carrying single, double or triple copies of w were crossed to generate flies carrying from two to five ectopic w genes. Within this range, z1-mediated suppression is insensitive to copynumber and does not distinguish between w genes that are in cis or in trans. Suppression does not require the juxtaposition of even numbers of w genes, but is extremely sensitive to chromosomal topology. When arranged in a tight cluster, in triple-copy TE derivatives, w genes are nonsuppressible. Breakpoints falling within TE35B and separating two functional w genes act as partial suppressors of z1. Similarly, breakpoints immediately proximal or distal to both w genes give partial suppression. This transvection-dependent downregulation of w genes may result from mis-activation of the X-chromosome dosage compensation mechanism.

ATP-Binding Cassette Transporters↗
PubMed1997

P-element insertion alleles of essential genes on the third chromosome of Drosophila melanogaster: correlation of physical and cytogenetic maps in chromosomal region 86E-87F.

We have established a collection of 2460 lethal or semi-lethal mutant lines using a procedure thought to insert single P elements into vital genes on the third chromosome of Drosophila melanogaster. More than 1200 randomly selected lines were examined by in situ hybridization and 90% found to contain single insertions at sites that mark 89% of all lettered subdivisions of the Bridges' map. A set of chromosomal deficiencies that collectively uncover approximately 25% of the euchromatin of chromosome 3 reveal lethal mutations in 468 lines corresponding to 145 complementation groups. We undertook a detailed analysis of the cytogenetic interval 86E-87F and identified 87 P-element-induced mutations falling into 38 complementation groups, 16 of which correspond to previously known genes. Twenty-one of these 38 complementation groups have at least one allele that has a P-element insertion at a position consistent with the cytogenetics of the locus. We have rescued P elements and flanking chromosomal sequences from the 86E-87F region in 35 lines with either lethal or genetically silent P insertions, and used these as probes to identify cosmids and P1 clones from the Drosophila genome projects. This has tied together the physical and genetic maps and has linked 44 previously identified cosmid contigs into seven "super-contigs" that span the interval. STS data for sequences flanking one side of the P-element insertions in 49 lines has identified insertions in the alphagamma element at 87C, two known transposable elements, and the open reading frames of seven putative single copy genes. These correspond to five known genes in this interval, and two genes identified by the homology of their predicted products to known proteins from other organisms.

Alleles↗