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At least 451 records · Page 25Linked to original sources
PubMed1998

Isolation and characterisation of smallminded, a Drosophila gene encoding a new member of the Cdc48p/VCP subfamily of AAA proteins.

Smallminded (smid) encodes a new member of the cdc48p/VCP subfamily of AAA proteins in Drosophila. The gene was isolated by plasmid rescue from a GAL4 enhancer trap line which shows reporter gene expression in neuroblasts, imaginal disks and a subset of sensory neurons. Larvae homozygous for the insert arrest development as second instar larvae and die without pupating. The most obvious defect in these larvae is a significantly reduced CNS, hence the naming of the gene as smallminded. The deduced amino acid sequence of smid contains a tandem duplication of the AAA nucleotide binding domain characteristic of the cdc48p/VCP subfamily. Overall, smid shares 33% identical residues with its closest relative, yeast L0919-chrXII and 26-29% with other members of the cdc48p/VCP subfamily. The most highly conserved regions of the predicted protein structure are found in and around the nucleotide binding domains. The gene is expressed at all developmental stages.

Amino Acid Sequence↗
PubMed1997

Genetic analysis of glutamate receptors in Drosophila reveals a retrograde signal regulating presynaptic transmitter release.

Postsynaptic sensitivity to glutamate was genetically manipulated at the Drosophila neuromuscular junction (NMJ) to test whether postsynaptic activity can regulate presynaptic function during development. We cloned the gene encoding a second muscle-specific glutamate receptor, DGluRIIB, which is closely related to the previously identified DGluRIIA and located adjacent to it in the genome. Mutations that eliminate DGluRIIA (but not DGluRIIB) or transgenic constructs that increase DGluRIIA expression were generated. When DGluRIIA is missing, the response of the muscle to a single vesicle of transmitter is substantially decreased. However, the response of the muscle to nerve stimulation is normal because quantal content is significantly increased. Thus, a decrease in postsynaptic receptors leads to an increase in presynaptic transmitter release, indicating that postsynaptic activity controls a retrograde signal that regulates presynaptic function.

Amino Acid Sequence↗
PubMed1998

A role for Abl in Notch signaling.

Abl is an axonal tyrosine kinase that has yet to be clearly linked to a receptor; Notch is a receptor for which the signaling pathway remains incompletely understood. We show here that Notch and abl mutations interact synergistically to produce synthetic lethality and defects in axon extension. Surprisingly, we cannot account for these axonal aberrations on the basis of changes in cell identity. We show, moreover, that Notch is present in the growth cones of extending axons, and that the Abl accessory protein Disabled binds to a signaling domain of Notch in vitro. We therefore speculate that Disabled and Abl may play a role in Notch signaling in Drosophila axons, perhaps by binding to the Notch intracellular domain.

Animals↗
PubMed2001

Differential expression of two scribble isoforms during Drosophila embryogenesis.

The tumour suppressor gene scribble (scrib) is required for epithelial polarity and growth control in Drosophila. Here, we report the identification and embryonic expression pattern of two Scrib protein isoforms resulting from alternative splicing during scrib transcription. Both proteins are first ubiquitously expressed during early embryogenesis. Then, during morphogenesis each Scrib protein displays a specific pattern of expression in the central and peripheral nervous systems, CNS and PNS, respectively. During germ band extension, the expression of the longer form Scrib1 occurs predominantly in the neuroblasts derived from the neuro-ectoderm and becomes later restricted to CNS neurones as well as to the pole cells in the gonads. By contrast, the shorter form Scrib2 is strongly expressed in the PNS and a subset of CNS neurones.

Alternative Splicing↗
PubMed2002

A P-insertion screen identifying novel X-linked essential genes in Drosophila.

The recent determination and annotation of the entire euchromatic sequence of the Drosophila melanogaster genome predicted the existence of about 13600 different genes (Science 287 (2000) 2185; http://www.fruitfly.org/annot/index.html). In parallel, the Berkeley Drosophila Genome Project (BDGP) has undertaken systematic P-insertion screens, to isolate new lethals and misexpressing lines. To date, however, the genes of the X chromosome have been under-represented in the screens performed. In order both to characterize several X-linked genes of prime interest to our laboratories and contribute to the collection of lethal P-insertions available to the community, we performed a P-insertion mutagenesis of the X chromosome. Using the PlacW and PGawB P-elements as mutagens, we generated two complementary sets of enhancer-trap lines, l(1)(T)PL and l(1)(T)PG, respectively, which both contain a reporter gene whose developmental expression can be monitored when driven by nearby enhancer sequences. We report here the characterization of 260 new insertions, mapping to 133 different genes or predicted CGs. Of these, 83 correspond to genes for which no lethal mutation had yet been reported. For 64 of those, we could confirm that lethality was solely due to the P-element insertion. The primary molecular data, reporter gene expression patterns (observed in embryos, third instar larvae and adult ovaries) and proposed CG assignment for each strain can be accessed and updated on our website at the following address: http://www-cbd.ups-tlse.fr:8080/screen.

Animals↗
PubMed2002

Drosophila MEF2 is a direct regulator of Actin57B transcription in cardiac, skeletal, and visceral muscle lineages.

To identify regulatory events occurring during myogenesis, we characterized the transcriptional regulation of a Drosophila melanogaster actin gene, Actin 57B. Act57B transcription is first detected in visceral muscle precursors and is detectable in all embryonic muscles by the end of embryogenesis. Through deletion analysis we identified a 595 bp promoter element that was sufficient for high levels of expression in all three muscle lineages. This fragment contained a MEF2 binding site conserved between D. melanogaster and Drosophila virilis which bound MEF2 protein in embryo nuclear extracts. Mutation of the MEF2 site severely reduced promoter activity in embryos, and in Mef2 mutants Act57B expression was severely decreased, demonstrating MEF2 is an essential regulator of Act57B. We also showed that MEF2 likely acts synergistically with factors bound to additional sequences within the 595 bp element. These findings underline the importance of MEF2 in controlling differentiation in all muscle lineages. Our experiments reveal a novel regulatory mechanism for a structural gene where high levels of expression in all embryonic muscles is regulated through a single transcription factor binding site.

Actins↗
PubMed2002

Temperature compensation and temporal expression mediated by an enhancer element in Drosophila.

A comparison of the activity of genetic elements from the regulatory region of the Drosophila melanogaster Deformed gene during embryogenesis and adult life reveals important similarities and differences. The 2.7 kb epidermal autoregulatory enhancer (EAE) of the Deformed gene drives expression of a beta-galactosidase reporter in unique spatial and temporal patterns in the adult antennae; this pattern is insensitive to temperature effects. The Deformed regulatory region possesses distinct enhancer elements that can direct the expression of a beta-galactosidase reporter spatially and temporally. A 120 bp region can reproduce the general features of the larger EAE fragment. The Deformed binding site is essential for temporal and spatial expression of beta-galactosidase during embryogenesis but is not required in the adult.

Animals↗
PubMed2002

Requirements of high levels of Hedgehog signaling activity for medial-region cell fate determination in Drosophila legs: identification of pxb, a putative Hedgehog signaling attenuator gene repressed along the anterior-posterior compartment boundary.

We show that high levels of Hedgehog signaling activity are essential for medial-region patterning in Drosophila legs. In mid-to-late third instar leg discs, high levels of Hedgehog signals repress the transcription of pxb, a newly identified gene encoding a transmembrane protein expressed specifically in the anterior compartment. Misexpression experiments indicate that Pxb may serve as a Hedgehog signaling attenuator capable of acting prior to Hedgehog-Patched interactions, suggesting that Hedgehog signaling in leg discs includes a pxb-repression-mediated positive feedback loop. RNA interference and clonal analysis show that neither Wingless nor Decapentaplegic signaling is required for pxb repression but high levels of Wingless signaling activity are essential for patterning in the leg ventral medial region.

Amino Acid Sequence↗
PubMed1996

The function of type IV collagen during Drosophila muscle development.

Type IV collagen forms a network that provides the major structural support for basement membranes. Basement membranes are specialized forms of extracellular matrix with important functions in development. One collagen gene (Dcg1) was characterized in Drosophila melanogaster and shown to encode a collagen chain related to vertebrate basement membrane type IV collagen chains. Therefore, to access the functional importance of type IV collagen during Drosophila myogenesis, we adopted two different approaches to decrease the Dcg1 gene expression in Drosophila embryos. We describe, here, that the decrease in Dcg1 gene expression causes, in particular, defective muscle attachments. These mutant phenotypes suggest that type IV collagen acts to stabilize cell-matrix interactions.

Animals↗
PubMed1998

saliva, a new Drosophila gene expressed in the embryonic salivary glands with homologues in plants and vertebrates.

saliva (slv) transcription begins at the salivary gland placodes and continues on throughout development as salivary glands invaginate and reach their final location and morphology. saliva is located cytogenetically in 76A/B, and encodes a 226-amino-acid protein with four hydrophobic domains. A Northern blot detects a 1.6-kb transcript throughout development. Database similarity searches reveal homology to proteins from Caenorhabditis, Lilium, Medicago and mouse.

Amino Acid Sequence↗
PubMed1999

Cell-type specific modular regulation of derailed in the Drosophila nervous system.

The derailed (drl) gene encodes a receptor tyrosine kinase (RTK) that governs aspects of axon guidance and muscle-epidermal interactions in the Drosophila embryo. To determine the types of neurons that express drl, we have examined a series of drl promoter fusions to axon-targeted reporters. We have identified enhancers that drive reporter expression in four distinct subtypes of embryonic neurons, all of which project axons in the anterior commissure of the developing nervous system. We also identified enhancers driving expression in the drl-expressing muscles and epidermal attachment cells. These enhancers define the classes of neurons projecting in the anterior commissure and can be used to precisely define axon pathfinding errors in drl and other mutants.

Animals↗
PubMed2002

Decoding cis-regulatory DNAs in the Drosophila genome.

Cis-regulatory DNAs control the timing and sites of gene expression during metazoan development. Changes in gene expression are responsible for the morphological diversification of metazoan body plans. However, traditional methods for the identification and characterization of cis-regulatory DNAs are tedious. During the past year, computational methods have been used to identify novel cis-DNAs within the entire Drosophila genome. These methods change the way that cis-DNAs will be analyzed in future studies and offer the promise of unraveling complex gene networks.

Animals↗
PubMed1994

Transient posterior localization of a kinesin fusion protein reflects anteroposterior polarity of the Drosophila oocyte.

BACKGROUND: During oogenesis in Drosophila, determinants that will dictate abdomen and germline formation are localized to the 'polar plasm' in the posterior of the oocyte. Assembly of the polar plasm involves the sequential localization of several messenger RNAs and proteins to the posterior of the oocyte, beginning with the localization of oskar mRNA and Staufen protein during stages 8 and 9 of oogenesis. The mechanism by which these two early components accumulate at the posterior is not known. We have investigated whether directed transport along microtubules could be used to accomplish this localization. RESULTS: We have made a fusion protein composed of the bacterial beta-galactosidase enzyme as a reporter, joined to part of the plus-end-directed microtubule motor, kinesin, and have found that the fusion protein transiently localizes to the posterior of the oocyte during stages 8 and 9 of oogenesis. Treatment with the microtubule-depolymerizing agent colchicine prevents both the localization of the fusion protein and the posterior transport of oskar mRNA and Staufen protein. Furthermore, the fusion protein localizes normally in oocytes mutant for either oskar and staufen, but not in other mutants in which oskar mRNA and Staufen protein are mislocalized. CONCLUSIONS: Association with a plus-end-directed microtubule motor can promote posterior localization of a reporter protein during oogenesis. The genetic requirements for this localization and its sensitivity to colchicine, both of which are shared with the posterior transport of oskar mRNA and Staufen protein, suggest that similar mechanism may function in both processes.

Adenosine Triphosphate↗
PubMed2003

Structural and dynamic functions establish chromatin domains.

Drosophila and mammalian proteins protect genes from heterochromatic repression in Saccharomyces cerevisiae by two different mechanisms. Factors termed genuine boundary activities (BAs) establish a structural, unidirectional bulwark against heterochromatin. In contrast, factors termed desilencing activities (DAs) act by the formation of a bidirectional, euchromatic island that blocks spreading of heterochromatin. The Drosophila boundary protein BEAF and, unexpectedly, the mammalian factor Sp1 exhibited a robust BA in yeast. In contrast, mammalian CTCF, Drosophila GAGA factor, yeast Gcn5p, and many mammalian transcription factors, although inactive as upregulators of nonsilenced genes, work as DAs. DAs but not BAs protect telomere-linked genes from silencing, presumably due to looping of telomeres and ensuing multidirectional silencing. The data demonstrate that "genetic autonomy" of chromatin domains is established by both passive and active mechanisms.

Animals↗
PubMed2003

Coupling cell growth, proliferation, and death. Hippo weighs in.

Four recent papers describe the characterization in Drosophila of Hippo, a serine/threonine kinase of the Sterile 20 (STE20) group, resembling Mst1 and Mst2. Hippo restricts cell growth and cell proliferation, promotes cell death, and interacts with the tumor suppressors Salvador and Warts. This, together with the ability of Mst2 to rescue hippo mutant phenotypes, argues that Mst/Hippo proteins are tumor suppressors.

Animals↗
PubMed2006

Mapping candidate genes for Drosophila melanogaster resistance to the parasitoid wasp Leptopilina boulardi.

Drosophila melanogaster resistance against the parasitoid wasp Leptopilina boulardi is under the control of a single gene (Rlb), with two alleles, the resistant one being dominant. Using strains bearing deletions, we previously demonstrated that the 55E2-E6; 55F3 region on chromosome 2R is involved in the resistance phenomenon. In this paper, we first restricted the Rlb containing region by mapping at the molecular level the breakpoints of the Df(2R)Pc66, Df(2R)P34 and Df(2R)Pc4 deficiencies, using both chromosomal in situ hybridization and Southern analyses. The resistance gene was localized in a 100 kb fragment, predicted to contain about 10 different genes. Male recombination genetic experiments were then performed, leading to identification of two possible candidates for the Rlb gene. Potential involvement of one of this genes, edl/mae, is discussed.

Animals↗
PubMed1998

Characterization of lethal Drosophila melanogaster alpha-actinin mutants.

We have partially characterized four Drosophila melanogaster alpha-actinin gene mutants, I(1)2Cb1, I(1)2Cb2, I(1)2Cb4, and I(1)2Cb5. We demonstrate that in each case the mutation is caused by a chromosomal rearrangement that precludes normal protein synthesis. In the absence of alpha-actinin, flies complete embryogenesis and develop into flaccid larvae that die within approximately 24 hr. These larvae have noticeable muscle dysfunction at hatching, although they, nevertheless, are capable of escaping from the egg membranes and of subsequent crawling movements. During larval development muscles degenerate, progressively limiting mobility and ultimately causing death. Electron microscopy of mutant muscle fibers reveals that myofibrils are grossly disrupted in one day old larvae and that electron-dense structures reminiscent of those seen in human nemaline myopathies are present throughout larval life. Our work rigorously demonstrates that alpha-actinin deficiencies are the cause of I(1)2Cb muscle defects. We anticipate that the alpha-actinin mutants described herein will facilitate in vivo tests of spectrin superfamily protein domain functions using a combination of directed mutagenesis and germline transformation.

Actinin↗
PubMed2002

Towards a male-only release system for SIT with the Queensland fruit fly, Bactrocera tryoni, using a genetic sexing strain with a temperature-sensitive lethal mutation.

Flies that are homozygous for the recessive autosomal mutation bent wings have a limited ability to fly and are less tolerant of high temperatures than normal flies in both the egg and puparial stages. The differences between the mutant and normal flies were found sufficient to be the basis of a genetic sexing strain. Genetic sexing strains were created using translocations of the autosome bearing the wild-type allele of bent wings (chromosome 2) to the Y chromosome, and crossing male flies carrying the translocation to mutant bent wings females. In the resulting strain, the females were homozygous for the bent wings mutation and the males were phenotypically normal for wing characters. Several translocations were recovered after irradiation, but only one translocation involving chromosome 2 was both stable and expressed in a stock that was vigorous enough for long-term viability. Unfortunately, all stocks containing the translocation showed high levels of temperature-dependent lethality, including, inexplicably, both males and females. Translocation stocks showing this effect included bent wings, another second chromosome mutation, white marks, and an otherwise normal stock. This phenomenon is probably rare, as it has not been reported before. It is likely that bent wings could be suitably used with another translocation.

Animals↗