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PubMed2003

Searching for sleep mutants of Drosophila melanogaster.

The functions of sleep are still unknown, but are probably related to cellular and molecular aspects of neural function. To better understand the benefits that sleep may bring at the cellular level, recent studies have employed Drosophila melanogaster as a model system and shown that fruit flies share the fundamental features of mammalian sleep. As in mammals, sleep in Drosophila is characterized by increased arousal threshold and by changes in brain electrical activity. Fly sleep is homeostatically regulated independent of the circadian clock, is modulated by stimulants and hypnotics, and is affected by age. Also, fly sleep is associated with changes in brain gene expression similar to those observed in mammals. While Drosophila neurobiology is sufficiently complex to permit meaningful generalizations to mammals and humans, Drosophila genetics is simple enough to allow a rapid mutagenesis screening. An ongoing mutagenesis study has screened approximately 5000 mutant Drosophila lines and found that sleep amount, sleep pattern, and the homeostatic regulation of sleep are highly conserved phenotypes in flies. So far, this study has identified 10 short sleeper lines and 4 lines that show no sleep rebound after sleep deprivation. Ultimately, the characterization of these lines should help identifying crucial cellular pathways involved in the regulatory mechanisms of sleep and its functional consequences.

Animals↗
PubMed2004

The calpain-system of Drosophila melanogaster: coming of age.

Drosophila melanogaster is one of the most popular and powerful model organisms that help our understanding of mammalian (human) life processes at the molecular level. Calpains are Ca(2+)-activated cytoplasmic proteases thought to play multiple roles in intracellular signal processing by limited proteolysis of target substrate proteins, thereby changing their function. The calpain superfamily consists of 14 genes in mammals, but only 4 genes in Drosophila. One may assume that the calpain system, i.e. recognizing calpain-dependent life processes and identifying the substrates cleaved while exerting their functions, would prove easier to solve in Drosophila than in mammals. Recently, major progress has been made in characterizing Drosophila Calpain A, Calpain B and Calpain C. The fourth member, Calpain D (or SOL), was analyzed earlier. At this juncture, it seems justifiable to summarize our knowledge about the Drosophila enzymes, in comparison to the ubiquitous mammalian ones, as regards structure-function relations, mode of activation by Ca(2+) and other factors, inhibition, potential targeting, expression pattern in vivo, etc. Equipped with all this information, we may now embark on the genetic modification of family members, interpreting mutant phenotypes in terms of the cell biology of calpains.

Amino Acid Sequence↗
PubMed1994

Gross chromosome rearrangements mediated by transposable elements in Drosophila melanogaster.

A combination of cytogenetic and molecular analyses has shown that several different transposable elements are involved in the restructuring of Drosophila chromosomes. Two kinds of elements, P and hobo, are especially prone to induce chromosome rearrangements. The mechanistic details of this process are unclear, but, at least some of the time, it seems to involve ectopic recombination between elements inserted at different chromosomal sites; the available data suggest that these ectopic recombination events are much more likely to occur between elements in the same chromosome than between elements in different chromosomes. Other Drosophila transposons also appear to mediate chromosome restructuring by ectopic recombination; these include the retrotransposons BEL, roo, Doc and I and the foldback element FB. In addition, two retrotransposons, HeT-A and TART, have been found to be associated specifically with the ends of Drosophila chromosomes. Very limited data indicate that transposon-mediated chromosome restructuring is occurring in natural populations of Drosophila. This suggests that transposable elements may help to shape the structure of the Drosophila genome and implies that they may have a similar role in other organisms.

Animals↗
PubMed2005

Production and N-glycan analysis of secreted human erythropoietin glycoprotein in stably transfected Drosophila S2 cells.

Schneider 2 (S2) cells from Drosophila melanogaster have been used as a plasmid-based, non-lytic expression system for foreign proteins. Here, a plasmid encoding the human erythropoietin (hEPO) gene fused with a hexahistidine (His(6)) tag under the control of the Drosophila metallothionein (MT) promoter was stably transfected into Drosophila S2 cells. After copper sulfate induction, transfected S2 cells were found to secrete hEPO with a maximum expression level of 18 mg/L and a secretion efficiency near 98%. The secreted hEPO from Drosophila S2 had an apparent molecular weight of about 23-27 kDa which was significantly lower than a recombinant hEPO expressed in Chinese hamster ovary (CHO) cells (about 36 kDa). N-glycosidase F digestion almost completely eliminated the difference and resulted in the same molecular weight ( approximately 20 kDa) of de-N-glycosylated hEPO proteins. These data suggest that recombinant hEPO from S2 cells was modified with smaller N-glycans. Subsequently, the major N-glycans were identified following glycoamidase A digestion, labeling with 2-aminopyridine (PA), and two-dimensional high-performance liquid chromatography (HPLC) analysis in concert with exoglycosidase digestion. This analysis of N-glycans revealed that hEPO was modified to include paucimannosidic glycans containing two or three mannose residues with or without core fucose. A similar glycosylation pattern was observed on a recombinant human transferrin expressed in S2 cells. These results provide a detailed analysis of multiple N-glycan structures produced in a Drosophila cell line that will be useful in the subsequent application of these cells for the generation of heterologous glycoproteins.

Animals↗
PubMed1993

Monoclonal antibody labels olfactory and visual pathways in Drosophila and Apis brains.

We employed a monoclonal antibody raised against Drosophila brain homogenate for a comparative immunocytochemical analysis of visual and olfactory pathways in brains of two insect species. On Western blots of Drosophila and Apis nervous tissue, antibody fb45 recognized an antigen with an apparent molecular weight higher than 180 kD. Application of the antibody to sections of Drosophila and Apis brain stained certain interneurons which conspicuously fasciculate in common tracts or neuropilar compartments. Both in Drosophila and in Apis, the antigen was also expressed on the perineural sheath and granular cell compartments in the majority of neuronal cell bodies. The antibody stained monopolar cells in the visual system of both species, and in Apis those fibers of the anterior superior optic tract which link the medulla with the mushroom bodies. In Drosophila, bundles of Kenyon cells of the mushroom bodies were stained. In worker bees and drones, the relay neurons of the median and lateral antennoglomerular tracts were labelled. Since the recognition of the antigen does not require fixation, the antibody can be employed to label selectively living neurons in dissociated cell culture. This opens up the possibility for future functional studies on the role of the antigen in vitro.

Animals↗
PubMed2005

Hearing in Drosophila: development of Johnston's organ and emerging parallels to vertebrate ear development.

In this review, I describe recent progress toward understanding the developmental genetics governing formation of the Drosophila auditory apparatus. The Drosophila auditory organ, Johnston's organ, is housed in the antenna. Intriguingly, key genes needed for specification or function of auditory cell types in the Drosophila antenna also are required for normal development or function of the vertebrate ear. These genes include distal-less, spalt and spalt-related, atonal, crinkled, nanchung and inactive, and prestin, and their vertebrate counterparts Dlx, spalt-like (sall), atonal homolog (ath), myosin VIIA, TRPV, and prestin, respectively. In addition, Drosophila auditory neurons recently were shown to serve actuating as well as transducing roles, much like their hair cell counterparts of the vertebrate cochlea. The emerging genetic and physiologic parallels have come as something of a surprise, because conventional wisdom holds that vertebrate and invertebrate hearing organs have separate evolutionary origins. The new findings raise the possibility that auditory organs are more ancient than previously thought and indicate that Drosophila is likely to be a powerful model system in which to gain insights regarding the etiologies of human deafness disorders.

Animals↗
PubMed1987

Genotoxic effects of cisplatin in somatic tissue of Drosophila melanogaster.

Third instar larvae of Drosophila melanogaster transdihybrid for mwh and flr were exposed to varying concentrations of cisplatin by feeding on dry media wetted with aqueous solutions of the test compound. Larval feeding continued until pupation, and surviving transdihybrid adults were collected seven days following commencement of feeding. Wings of adults were removed and scored under 400X magnification for the presence of twin spots and single spots comprised of clones of cells possessing malformed wing hairs. Cisplatin was found to induce both twin spots and single spots, and significant (p less than 0.05) linear concentration-response relationships were obtained with respect to the induction of all endpoints. Induction of twin spots demonstrates that cisplatin induces mitotic recombination in the somatic tissue of Drosophila larvae. This capacity to induce mitotic exchange in the somatic tissue of Drosophila compares well with the compound's reported ability to induce chromosome breaks in Drosophila germ cells [Brodberg et al. 1983]. However, not all compounds possess similar genotoxic profiles in the somatic and germ tissue of Drosophila.

Animals↗
PubMed1987

Specific reduction of N,N-dimethylnitrosamine mutagenicity in Drosophila melanogaster by dimethyl sulfoxide.

Dimethyl sulfoxide (DMSO) used as a solvent has been observed to complicate mutagenicity screens by interacting with tested chemicals to yield false positives or negatives. We have used DMSO as a solvent in the Drosophila melanogaster recessive sex-linked lethal mutation assay and find that it reduces, but does not abolish, the detectable mutagenicity of N,N-dimethylnitrosamine (DMN). Its use as a solvent with procarbazine, another promutagen, shows no effect on mutagenicity in Drosophila. DMSO does not exhibit a general inhibitory action on microsome activity when ecdysone 20-monooxygenase activity is used as a measure of cytochrome P-450 activity. We were unable to detect the low DMN demethylase activity in the strain used. Hence, the inhibitory effect of DMSO in Drosophila at both the physiological and biological level appears to be limited and not general in action. Because DMN and DMSO are similar in structure, it is possible that DMSO is interacting with a DMN demethylase in Drosophila. This might lead to a reduction in the conversion of DMN to a mutagen. Consequently, from the results of this study and others DMSO should be used cautiously as a solvent in Drosophila mutagen screening.

Animals↗
PubMed1983

Aberrant splicing of Drosophila alcohol dehydrogenase transcripts in Saccharomyces cerevisiae.

We have investigated the ability of transcripts of the Drosophila melanogaster alcohol dehydrogenase gene to be spliced in Saccharomyces cerevisiae. The alcohol dehydrogenase gene was cloned in S. cerevisiae on a 2 micron DNA-based vector and a hybrid yeast actin-Drosophila alcohol dehydrogenase gene was constructed to demonstrate that transcripts encoded on a 2 micron plasmid could be accurately and efficiently spliced. Transcription of the Drosophila gene occurred in yeast with and without a yeast promoter. The transcripts were polyadenylated and terminated approximately 600 nucleotides distal to the polyadenylation site used in Drosophila. In yeast no splicing of the two introns within the alcohol dehydrogenase coding sequence was detected. However, the leader sequence was apparently spliced using the same 3' splice site as is used in adult flies, but a different 5' splice site. This result may be partly explained by the existence in the Drosophila gene of a sequence which is believed to be required for splicing in S. cerevisiae.

Alcohol Dehydrogenase↗
PubMed1989

Molecular characterization and expression of the (Na+ + K+)-ATPase alpha-subunit in Drosophila melanogaster.

The (Na+ + K+)-ATPase (sodium pump) is an ouabain-sensitive, electrogenic ion pump responsible for maintaining the balance of sodium and potassium ions in almost all animal cells. Robust, ouabain-sensitive rubidium uptake, indicative of the sodium pump, was found in tissue-cultured Drosophila cells, and both larvae and adults die when fed a diet containing ouabain. A monoclonal antibody to the avian sodium pump alpha-subunit was found to cross-react with the Drosophila sodium pump alpha-subunit. Immunofluorescence microscopy was used to obtain a semi-quantitative view of the expression of the sodium pump in Drosophila tissues: high levels of the sodium pump were detected in malpighian tubules, indirect flight muscles and tubular muscles, and throughout the nervous system. The cDNA encoding this sodium pump alpha-subunit in Drosophila melanogaster was cloned, sequenced and expressed in mouse L cells. At the amino acid level, its deduced sequence of 1038 residues (the first such sequence for an invertebrate) is approximately 80% similar to alpha-subunit sequences reported for vertebrates. Only one gene was found in Drosophila, located on the third chromosome at position 93B. A restriction site polymorphism has been found, and several mutations exist that may involve the alpha-subunit gene.

Amino Acid Sequence↗
PubMed1990

Cloning and characterization of a Drosophila tyramine receptor.

Receptors for biogenic amines such as dopamine, serotonin and epinephrine belong to the family of receptors that interact with G proteins and share a putative seven transmembrane domain structure. Using a strategy based on nucleotide sequence homology between the corresponding genes, we have isolated Drosophila cDNA clones encoding a new member of the G protein-coupled receptor family. This protein exhibits highest homology to the human alpha 2 adrenergic receptors, the human 5HT1A receptor and a recently cloned Drosophila serotonin receptor. The corresponding mRNA is found predominantly in adult Drosophila heads. Membranes from mammalian cells expressing this receptor displayed high affinity binding sites for [3H]yohimbine, an alpha 2 adrenergic receptor antagonist (Kd = 4.45 x 10(-9) M). Tyramine was the most efficient of the putative Drosophila neurotransmitters at displacing [3H]yohimbine binding (EC50 = 1.25 x 10(-6) M). Furthermore tyramine induced an inhibition of adenylate cyclase activity in NIH 3T3 cells expressing this receptor. The Drosophila tyramine receptor that we have isolated might therefore be an invertebrate equivalent of the mammalian alpha 2 adrenergic receptors.

Amino Acid Sequence↗
PubMed1993

The expression pattern of a Drosophila homolog to the mouse transcription factor HNF-4 suggests a determinative role in gut formation.

A Drosophila gene, HNF-4(D), was selected by cross-hybridization with a probe to rat HNF-4 (hepatocyte nuclear factor 4), a steroid hormone receptor super-family member that plays an important role in liver-specific gene expression. The Drosophila gene matched the mouse gene in 60 out of 66 amino acids in the zinc finger DNA binding domain and in 140 out of 206 amino acids in the domain that specifies dimerization and ligand binding. HNF-4(D) is expressed in developing Drosophila embryos in mid-gut, fat bodies and malpighian tubules, a striking similarity to its limited expression in the adult intestine, liver and kidney of the mouse. Furthermore, Drosophila mutant that has a chromosome deletion spanning the HNF-4(D) locus fails to develop tissues where HNF-4(D) is expressed during late embryogenesis. These findings together with the earlier realization that the rat hepatocyte nuclear factor 3 (HNF-3) and forkhead, a Drosophila gene required for anterior and posterior gut formation, had virtually the identical DNA binding domain, lead us to speculate that a group of genes that participate in gut formation of invertebrates has survived in evolution to perform similar functions in mammals.

Amino Acid Sequence↗
PubMed2003

The mushroom bodies of Drosophila melanogaster: an immunocytological and golgi study of Kenyon cell organization in the calyces and lobes.

Golgi impregnations reveal a variety of dendritic morphologies amongst Kenyon cells in the mushroom bodies of Drosophila melanogaster. Different morphological types of Kenyon cells contribute axon-like processes to five divisions of the medial and vertical lobes. Four of these divisions have characteristic affinities to antibodies raised against aspartate, glutamate, and taurine. A newly described posterior subdivision of the medial lobe, here named the betac lobe with its vertical branch alphac, comprises glutamatergic Kenyon cells that are probably homologous to glutamatergic Kenyon cells in the cockroach and honey bee, and are the last neurons to differentiate. The first neurons to differentiate, which supply the gamma lobe, are equipped with clawed dendritic specializations and are the structural homologues of clawed class II Kenyon cells supplying the gamma lobes in cockroaches and honey bees. Three intermediate divisions lie between the betac lobe and gamma lobe. These are, from the back towards the front, the beta lobe, the beta' lobe, and a narrow division between beta' and gamma called the beta" lobe. The fused calyx of the Drosophila mushroom body is comparable to the double calyces of Hymenoptera, here exemplified by a basal taxon, Diprion pini. Further similarities between the hymenopteran calyces and those of Drosophila are suggested by the segregation of different types of Kenyon cell dendrites within the calyx neuropil. The organization of afferents from the antennal lobes also defines regions in the Drosophila calyx that may be homologous to the lip and basal ring regions of the honey bee calyces. As in honey bees, GABAergic processes densely invade Drosophila's calyces, which also contain a sparse but uniform distribution of octopaminergic elements. Microsc. Res. Tech. 62:151-169, 2003.

Animal Structures↗
PubMed1998

Cloning and developmental expression of a nuclear ubiquitin-conjugating enzyme (DmUbc9) that interacts with small heat shock proteins in Drosophila melanogaster.

In a two hybrid screen designed to identify proteins that interact with small heat shock proteins (sHsps), a Drosophila melanogaster homologue of yeast and human ubc9 (Dmubc9) was found to interact with Drosophila Hsp23. Further, two-hybrid system analysis reveals DmUbc9 interaction with Drosophila and mammalian Hsp27. In situ hybridization localizes Dmubc9 as a doublet at locus 21D on chromosome 2L, and genomic cloning of the gene reveals a single open reading frame without introns. The predicted Dmubc9 protein sequence shares a very high level of homology with mouse (85.4%) and human (> or = 82.9%) Ubc9. Genetic complementation analysis show that Dmubc9 functionally rescues a temperature-sensitive S. cerevisiae ubc9ts mutant. Co-immunoprecipitation with antibody raised against DmUbc9 confirms the interaction with Drosophila Hsp23 and Hsp26 and preferentially with Hsp27. The DmUbc9 protein, which localizes primarily to the nucleus in Drosophila S2 cells, is found at high levels in embryos but is also present at lower levels throughout development. The significance of the sHsp-Ubc9 interaction is discussed.

Amino Acid Sequence↗
PubMed2000

Drosophila von Hippel-Lindau tumor suppressor complex possesses E3 ubiquitin ligase activity.

Mutations of the von Hippel-Lindau (VHL) tumor suppressor gene predispose individuals to a variety of human tumors, including renal cell carcinoma, hemangioblastoma of the central nervous system, and pheochromocytoma. Here we report on the identification and characterization of the Drosophila homolog of VHL. The predicted amino acid sequence of Drosophila VHL protein shows 29% identity and 44% similarity to that of human VHL protein. Biochemical studies have shown that Drosophila VHL protein binds to Elongins B and C directly, and via this Elongin BC complex, associates with Cul-2 and Rbx1. Like human VHL, Drosophila VHL complex containing Cul-2, Rbx1, Elongins B and C, exhibits E3 ubiquitin ligase activity. In addition, we provide evidence that hypoxia-inducible factor (HIF)-1alpha is the ubiquitination target of both human and Drosophila VHL complexes.

Amino Acid Sequence↗
PubMed1999

Vertebrate homologs of Drosophila suppressor of fused interact with the gli family of transcriptional regulators.

The hedgehog (Hh) signaling pathway is crucial for pattern formation during metazoan development. Although originially characterized in Drosophila, vertebrate homologs have been identified for several, but not all, genes in the pathway. Analysis of mutants in Drosophila demonstrates that Suppressor of fused [Su(fu)] interacts genetically with genes encoding proteins in the Hh signal transduction pathway, and its protein product physically interacts with two of the proteins in the Hh pathway. We report here the molecular cloning and characterization of chicken and mouse homologs of Su(fu). The chick and mouse proteins are 27% identical and 53% similar at the amino acid level to the Drosophila melanogaster and Drosophila virilis proteins. Vertebrate Su(fu) is widely expressed in the developing embryo with higher levels in tissues that are known to be patterned by Hh signaling. The chick Su(fu) protein can physically interact with factors known to function in Hh signal transduction including the Drosophila serine/threonine kinase, Fused, and the vertebrate transcriptional regulators Gli1 and Gli3. This interaction may be significant for transcriptional regulation, as recombinant Su(fu) enhances the ability of Gli proteins to bind DNA in electrophoretic mobility shift assays.

Amino Acid Sequence↗
PubMed2002

It takes guts: the Drosophila hindgut as a model system for organogenesis.

The Drosophila hindgut is fruitful territory for investigation of events common to many types of organogenesis. The development of the Drosophila hindgut provides, in microcosm, a genetic model system for studying processes such as establishment (patterning) of an epithelial primordium, its internalization by gastrulation, development of left--right asymmetric looping, patterning in both the anteroposterior and dorsoventral axes, innervation, investment of an epithelium with mesoderm, reciprocal epitheliomesenchymal interactions, cell shape change, and cell rearrangement. We review the genetic control of these processes during development of the Drosophila hindgut, and compare these to related processes in other bilaterians, particularly vertebrates. We propose that caudal/Cdx, brachyenteron/Brachyury, fork head/HNF-3, and wingless/Wnt constitute a conserved "cassette" of genes expressed in the blastopore and later in the gut, involved in posterior patterning, cell rearrangement, and gut maintenance. Elongation of the internalized Drosophila hindgut primordium is similar to elongation of the archenteron and also of the entire embryonic axis (both during and after gastrulation), as well as of various tubules (e.g., nephric ducts, Malpighian tubules), as it is driven by cell rearrangement. The genes drumstick, bowl, and lines (which encode putative transcriptional regulators) are required for this cell rearrangement, as well as for spatially localized gene expression required to establish the three morphologically distinct subregions of the hindgut. Expression of signaling molecules regulated by drumstick, bowl, and lines, in particular of the JAK/STAT activator Unpaired at the hindgut anterior, may play a role in controlling hindgut cell rearrangement. Other cell signaling molecules expressed in the hindgut epithelium are required to establish its normal size (Dpp and Hh), and to establish and maintain the hindgut visceral mesoderm (Wg and Hh). Both maternal gene activity and zygotic gene activity are required for asymmetric left--right looping of the hindgut. Some of the same genes (caudal and brachyenteron) required for embryonic hindgut development also act during pupation to construct a new hindgut from imaginal cells. Application of the plethora of genetic techniques available in Drosophila, including forward genetic screens, should identify additional genes controlling hindgut development and thus shed light on a variety of common morphogenetic processes.

Animals↗
PubMed2001

Endocytosis in Drosophila: progress, possibilities, prognostications.

By many outside the field, endocytosis is often perceived as a "house-keeping" function performed via identical mechanisms in yeast and man. Recent discoveries have done much to reduce this misperception. (1) Endocytosis occurs via different mechanisms and different pathways in different cellular contexts. (2) Molecular mechanisms that regulate homologous pathways in unicellular and multicellular organisms show considerable variance. (3) Temporally controlled endocytosis of specific regulatory molecules underlies several important and intricate biological processes including synapse formation, synaptic plasticity, cell fate determination, and morphogen gradient formation. Interactions between endocytosis and cytoskeletal and signaling pathways have been particularly revealing. In this intellectual context, Drosophila has become invaluable as a metazoan genetic model in which to understand the many faces of endocytosis. This review discusses two aspects of work in Drosophila: (a) its contributions toward understanding fundamental mechanisms that underlie the operation of endocytic pathways; (b) how analyses in Drosophila provide insights into varied biological processes regulated by endocytosis. In addition, while offering our commentary on merits and limitations of Drosophila work, we speculate on likely areas for contributions and future research on endocytosis in Drosophila.

Animals↗