Biomedical subjects

Z Asztalos

Publications and source records attributed to Z Asztalos.

6 recordsLinked to original sources

PubMed2001

Dual-tagging gene trap of novel genes in Drosophila melanogaster.

A gene-trap system is established for Drosophila. Unlike the conventional enhancer-trap system, the gene-trap system allows the recovery only of fly lines whose genes are inactivated by a P-element insertion, i.e., mutants. In the gene-trap system, the reporter gene expression reflects precisely the spatial and temporal expression pattern of the trapped gene. Flies in which gene trap occurred are identified by a two-step screening process using two independent markers, mini-w and Gal4, each indicating the integration of the vector downstream of the promoter of a gene (dual tagging). mini-w has its own promoter but lacks a polyadenylation signal. Therefore, mini-w mRNA is transcribed from its own promoter regardless of the vector integration site in the genome. However, the eyes of flies are not orange or red unless the vector is incorporated into a gene enabling mini-w to be spliced to a downstream exon of the host gene and polyadenylated at the 3' end. The promoter-less Gal4 reporter is expressed as a fusion mRNA only when it is integrated downstream of the promoter of a host gene. The exons of trapped genes can be readily cloned by vectorette RT-PCR, followed by RACE and PCR using cDNA libraries. Thus, the dual-tagging gene-trap system provides a means for (i) efficient mutagenesis, (ii) unequivocal identification of genes responsible for mutant phenotypes, (iii) precise detection of expression patterns of trapped genes, and (iv) rapid cloning of trapped genes.

Animals↗

PubMed2000

Fruitless is in the regulatory pathway by which ectopic mini-white and transformer induce bisexual courtship in Drosophila.

Bisexual courtship in male Drosophila melanogaster may be induced in some circumstances. These include ectopic expression of the transformer (tra) gene, ectopic expression of the mini-white (mw) gene, and the homozygous presence of mutant alleles of the fruitless (fru) gene. Experiments were performed to determine if ectopic mw and fru, as well as ectopic tra and fru, acted in the same pathway to control courtship. Male flies homozygous for the frusat allele court females little if at all and males at a low level. When homozygous, the frusat allele suppresses the bisexual courtship induced by both ectopic mw and ectopic tra, indicating that the fru wild-type function is necessary for expression of the ectopic mw and ectopic tra effect. This demonstrates that fru shares a pathway controlling courtship behavior with these ectopically expressed genes.

Animals↗

PubMed1999

Sexual behaviour: Courting dissatisfaction.

A nuclear receptor, the product of the dissatisfaction gene, has been found to regulate Drosophila sexual behaviour, probably via its action in a small subset of neurons. The results shed new light on the genetic determination of sexual behaviour.

Animals↗

PubMed1999

The Drosophila melanogaster 60A chromosomal division is extremely dense with functional genes: their sequences, genomic organization, and expression.

We cloned and sequenced genomic DNA contigs spanning over 45 kb, surrounding the insertion site of the P-element that is responsible for the developmental defects in the ken and barbie (ken) mutant of Drosophila. This region harbors 10 functional transcription units, in addition to the already well-characterized TGFbeta-60A gene. These include the genes, undefined 1 (UD1), UD2, and UD3, each coding for proteins of unknown function, the ken gene encoding a new Krüppel-like putative transcription factor, the fly homologues of the mammalian mitochondrial trifunctional enzyme (thiolase), and the TAR DNA-binding protein-43 (TBPH), the first nonvertebrate member of the transmembrane 4 superfamily (TM4SF) gene, a new homeodomain gene, and a gene coding for a putative nuclear binding protein (PNBP) that is homologous to maleless, and a Copia-like element. UD3 exists in an intron of the maleless homologue, yet is expressed independent of it. The UD1 and TM4SF genes orient in a tail-to-tail manner with their 3' untranslated region sequences overlapping over 44 nucleotides. Thus the partial overlap and intraintronic organization permitted dense packing of the functional genes within a short segment of the genome.

Acetyl-CoA C-Acetyltransferase↗

PubMed1993

Protein phosphatase 1-deficient mutant Drosophila is affected in habituation and associative learning.

The learning and memory of Drosophila melanogaster strains carrying the Su-var(3)6(01) mutation, which is known to affect the structural gene of a protein phosphatase 1 isoenzyme, PP1(87B), were studied in various behavioral paradigms. Three lines of Drosophila comprising the Su-var(3)6(01) mutation in different genetic backgrounds were shown to have diminished protein phosphatase 1 activity and behavioral anomalies. Associative olfactory learning and visual conditioning were impaired. Olfactory acuity for the odorants used and response to electric shock were largely unchanged in the mutant lines. The motility and flight activity of the mutants were reduced. Habituation of the landing response, a nonassociative learning process, was more pronounced in heterozygotes of the mutants than in the wild-type control strains. Taken together with earlier data, the results indicate that protein phosphatase PP1(87B), while affecting several cellular processes, is also part of the biochemical machinery of various forms of neuromodulation in Drosophila.

Animals↗

PubMed1991

On the pharmacological phenocopying of memory mutations in Drosophila: alkylxanthines accelerate memory decay.

Theophylline and 3-isobutyl-1-methylxanthine, two cyclic nucleotide phosphodiesterase inhibitors, when fed to wild-type Drosophila adults, cause the rapid decay of learning index after training in a shock-odor learning paradigm. The drugs practically do not affect the olfactory acuity of flies, hence they influence the learning/memory process itself. The time courses of memory decay resemble those of the memory mutants rutabaga and amnesiac and, to a lesser extent, dunce2 and dunceM11. Theophylline further deteriorates the learning performance of dunceM11. Biochemical characterization of the inhibition of the two major phosphodiesterase isoenzymes in Drosophila by theophylline predicts only a slight inhibition of these enzymes in vivo, in accordance with the unchanged level of cAMP in wild-type fly heads during drug feeding. 8-Phenyltheophylline, an adenosine receptor antagonist in mammals, slightly retards memory decay in the wild-type. It is suggested that alkylxanthines induce memory decay in Drosophila by interfering with cAMP dynamics at more than one point of its metabolism.

1-Methyl-3-isobutylxanthine↗