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PubMed1993

Dense cluster of genes is located at the ecdysone-regulated 3C puff of Drosophila melanogaster.

The 3C11-12 polytene bands of the Drosophila melanogaster X chromosome give rise to a prominent puff, whose regression is triggered by the increase in the titre of the steroid hormone 20-hydroxyecdysone occurring before the metamorphosis. Here, we report the molecular characterization of three genes, named ng-2, ng-3 and ng-4, which we found to be closely linked to each other and to Sgs-4, Pig-1 and ng-1, three other genes previously mapped at this polytene region. All six genes are, in fact, arranged in a tightly linked cluster spanning a DNA segment of only 11 kb. With the exception of ng-4, all the clustered genes are highly expressed only during the larval life and share the same tissue-specificity, being mainly transcribed within the salivary glands. In addition, two members of the cluster, ng-1 and ng-2, show a very high degree of sequence homology, clearly indicating that they are related to each other by means of a duplication event. Interestingly to note, the entire cluster shows a peculiar genomic location, extending across two introns of the memory gene dunce, a large gene of Drosophila whose organization has proved to be remarkably complex.

Amino Acid Sequence↗

PubMed1993

A Drosophila gene encoding an epithelial membrane protein with homology to CD36/LIMP II.

The human cell surface transmembrane protein CD36 has important roles in cell adhesion and signal transduction. There is a related rat protein, LIMP II (also known as rLGP85), which is a well-characterized lysosomal membrane protein. The two proteins define a distinct family of receptor molecules with two membrane-spanning domains. We have identified a new member of this family, encoded by a Drosophila gene called emp (epithelial membrane protein). The emp protein, as predicted from the nucleotide sequence, is 519 amino acid residues long. It shows striking similarity throughout most of its sequence to both CD36 and LIMP II. Drosophila emp transcripts are expressed during embryogenesis in various epithelial cell types derived from the ectoderm. During larval development, we detect emp transcripts in the epithelial cells of wing imaginal discs, in the precursor cells for adult epidermal structures. These expression patterns suggest a role of emp protein in the development or cellular function of epithelial cells.

Amino Acid Sequence↗

PubMed1994

Mapping a mutator, mu2, which increases the frequency of terminal deletions in Drosophila melanogaster.

A mutator, mu2, in Drosophila melanogaster has been identified recently that potentiates the recovery of terminal deficiencies. The deleted chromosomes behave as if they had been capped; that is, they are protected from degradation and from fusion with other chromosome fragments. The mutator maps near the telomere on the left arm of chromosome 3. Using the selectable marker Aprt, 150 deficiencies for region 62 of the cytological map have been recovered. These deficiencies identify the map position of mu2 as 62B11-C1. A yeast artificial chromosome spanning this region has been subcloned into lambda phage, and the positions of deficiency breakpoints on either side of the mu2 gene have been identified within the subclones. These positions limit the location of the left end of the gene to a 23 kb region. In the course of these experiments, three additional, presumptive mutant alleles were identified, suggesting that other mutator alleles remain undiscovered in many standard laboratory stocks.

Adenine Phosphoribosyltransferase↗

PubMed1995

In situ quantification of hsp70 and alpha-beta transcripts at 87A and 87C loci in relation to hsr-omega gene activity in polytene cells of Drosophila melanogaster.

The hsp70-coding duplicate loci at the 87A and 87C sites (the 87C site also carries heat-inducible alpha-beta repeats) in polytene nuclei are known to puff to different levels under conditions in which heat shock does not induce the non-protein-coding hsr-omega gene at the 93D site. To understand the basis of this unequal puffing, the levels of hsp70 and alpha-beta transcripts at the 87A and 87C heat shock loci in polytene chromosomes of Drosophila melanogaster were quantified in situ by hybridization of antisense RNA probes after treatment with heat shock, benzamide, colchicine, heat shock followed by benzamide or heat shock in the presence of colchicine in salivary glands of late third instar larvae. Heat shock, resulting in equal puffing of the 87A and 87C loci, increased the hsp70 transcripts at both sites in proportion to the numbers of hsp70 gene copies at the two loci; levels of alpha-beta transcripts were also elevated at the 87C site following heat shock. Heat shock followed by benzamide treatment, which results in a larger puff at 87A, caused an increase in hsp70 transcripts per gene copy at 87A and a decrease at 87C without any effect on the alpha-beta transcripts; heat shock in the presence of colchicine, which causes the 87C puff to be larger than 87A, resulted in a decrease in hsp70 RNA at 87A but an increase in the levels of hsp70 as well as alpha-beta transcripts at the 87C site.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

The raspberry locus encodes Drosophila inosine monophosphate dehydrogenase.

Investigation of an enhancer-trap line exhibiting testis-specific beta-galactosidase expression led to the isolation of the Drosophila gene encoding inosine monophosphate dehydrogenase (IMPD), the rate-limiting enzyme in guanine nucleotide synthesis, which has been implicated in cell cycle control and malignant transformation. Northern and in situ hybridization analysis demonstrated that the gene has a complex expression pattern involving several independently regulated transcripts. Two ubiquitous, but highly ovary enriched, transcripts of 2.5 and 1.9 kb are expressed in the nurse cells and delivered to the oocyte, whilst a 0.9 kb transcript is found exclusively in the testis. The 2.5 kb transcript encodes a 58 kDa protein, which is highly similar in length and sequence to mouse and human IMPDs and is presumably required for GTP synthesis during early embryogenesis. Over-expression of this cDNA in Escherichia coli yielded a product of the predicted size, which was demonstrated to possess IMPD activity in a spectrophotometric assay. The coding capacity of the other transcripts is currently uncertain. We present evidence that IMPD is the product of the raspberry (ras) locus at 9E and the functions of the gene are discussed in relation to the phenotypes of ras mutants.

Amino Acid Sequence↗

PubMed2001

Effects of mutations at the stambh A locus of Drosophila melanogaster.

We report novel findings on the cytogenetic location, functional complexity and maternal and germline roles of the stambh A locus of Drosophila melanogaster. stmA is localized to polytene bands 44D1.2 on 2R. stmA mutations are of two types: temperature-sensitive (ts) adult and larval paralytic or unconditional embryonic or larval lethal. Twelve alleles reported in this study fall into two intragenic complementing groups suggesting that stmA is a complex locus with more than one functional domain. Some unconditional embryonic lethal alleles show a 'neurogenic' phenotype of cuticle loss accompanied by neural hypertrophy. It is shown that embryos of ts paralytic alleles also show mild neural hypertrophy at permissive temperatures while short exposure to heat induces severe cuticle loss in these embryos. stmA exerts a maternal influence over heat-induced cuticle loss. Unconditional embryonic lethal alleles of stmA are also germline lethal.

Alleles↗

PubMed2003

Analysis of the amplification and transcription of the C3-22 gene of Rhynchosciara americana (Diptera: Sciaridae) in transgenic lines of Drosophila melanogaster.

Drosophila melanogaster was transformed with an 18 kb fragment of the C3 DNA puff of Rhynchosciara americana, including the C3-22 gene and the origins of replication that direct amplification. Different tissues and developmental stages of five independent transgenic lines were analyzed by quantitative Southern blot hybridization. No indication was found that the transformed fragment was amplified, strongly suggesting that factors involved in DNA puff amplification have not been conserved in Drosophila. Transcription of the C3-22 gene in the transgenic lines was found to be at a low and constitutive level throughout development. These results indicate that, unlike other DNA puff genes, the factors that regulate the C3-22 gene are not conserved in Drosophila.

Animals↗

PubMed2005

Genetic regions that interact with loss- and gain-of-function phenotypes of deltex implicate novel genes in Drosophila Notch signaling.

The Notch signaling pathway is an evolutionarily conserved mechanism that regulates many cell fate decisions. The deltex (dx) gene encodes an E3-ubiquitin ligase that binds to the intracellular domain of the Notch protein and regulates Notch signaling in a positive manner. However, it is still not clear how Dx does this. We generated a transgenic line, GMR-dx, which overexpresses dx in the developing Drosophila eye disc. The GMR-dx line showed a rough-eye phenotype, specific transformation of a photoreceptor cell (R3 to R4), and a rotation defect in the ommatidia. This phenotype was suppressed in combination with a dx loss-of-function mutant, indicating that it was due to a dx gain-of-function. We previously reported that overexpression of Dx results in the stabilization of Notch in late endosomes. Here, we found that three motifs in Dx, a region that binds to Notch, a proline-rich motif and a RING-H2 finger, were required for this stabilization, although the relative activity of these variants in this assay did not always correspond to the severity of the rough-eye phenotype. In an attempt to identify novel genes of the Notch pathway, we tested a large collection of chromosomal deficiencies for the ability to modify the eye phenotypes of the GMR-dx line. Twelve genomic segments that enhanced the rough-eye phenotype of GMR-dx were identified. To evaluate the specificity of these interactions, we then determined whether the deletions also interacted with the wing phenotypes associated with a loss-of-function mutation of dx, dx24. Analyses based on whole-genome information allowed us to conclude that we have identified two novel loci that probably include uncharacterized genes involved in Dx-mediated Notch signaling.

Amino Acid Motifs↗

PubMed2006

Identification of quantitative trait loci for larval morphological traits in interspecific hybrids of Ochlerotatus triseriatus and Ochlerotatus hendersoni (Diptera: Culicidae).

Ochlerotatus triseriatus is the natural vector of La Crosse virus, a common cause of pediatric encephalitis in the United States; the closely related Ochlerotatus hendersoni transmits this virus at low frequency. Adults of these mosquito species are difficult to distinguish morphologically; however, the larval stages show species-specific differences in several characters. We identified genomic regions contributing to the differences between the larvae of these species through interspecific hybridizations. Quantitative trait loci (QTL) were identified by standard interval mapping techniques and by univariate marker association analyses. We examined 159 F(2) progeny from an Oc. hendersoni female by Oc. triseriatus male interspecific cross for variation in the number of saddle and siphon hair branches, attachment of the acus, and morphology of the anal papillae. At least one putative QTL was identified for each of the phenotypes examined. QTL most commonly mapped to linkage group (LG) III, although QTL were identified on LGI and LGII for three phenotypes each. Several of these QTL, and particularly those on LGIII, also map to genome regions controlling adult female body size and ability to orally transmit La Crosse virus. Further studies are required to elucidate the relationships among these traits and the impact they may have had on the ecological specialization and speciation of these mosquitoes.

Alleles↗

PubMed1992

Structure and expression of bombyxin-related peptide genes of the moth Samia cynthia ricini.

From the genomic DNA of the moth Samia cynthia ricini, we cloned and characterized six clustered genes that encode precursor molecules for peptides structurally related to bombyxin, a Bombyx mori brain secretory peptide that is structurally like insulin and functionally like the prothoracicotropic hormone. The precursor molecules deduced from these genes have the domain organization of signal peptide/B-chain/C-peptide/A-chain, as in preprobombyxins and preproinsulins. The Samia bombyxin-related peptide (SBRP) genes are classified into families A and B according to their sequence homology. Two genes belonging to different families are arranged close to each other to form a pair with opposite transcriptional orientations (A-1/B-1, A-2/B-2, and A-3/B-3). None of these genes have introns, and gene B-3 has an in-frame stop codon representing a pseudogene. Four genes, A-1, A-3, B-1, and B-2, are expressed in Samia brain. Genomic Southern hybridization suggests that the Samia genome contains many other SBRP genes.

Amino Acid Sequence↗

PubMed1988

Functional mapping of an AcNPV immediately early gene which augments expression of the IE-1 trans-activated 39K gene.

An early gene which augments the expression of the delayed early/late 39K gene of the baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV) was identified by functional mapping. Transient expression of the plasmid p39CAT, containing the bacterial chloramphenicol acetyltransferase coding sequences under the control of the promoter of the 39K protein, was observed in cells cotransfected with AcNPV DNA digested with several restriction endonucleases. However, when p39CAT was cotransfected with viral DNA digested with Bg/II restriction endonuclease, no CAT activity could be detected. To map the location of the Bg/II-sensitive sequences required for efficient expression of 39CAT, p39CAT and Bg/II-digested viral DNA were cotransfected with a PstI library of AcNPV DNA. The PstI-N fragment restored 39CAT activity. A major early 1.3-kb transcript from this fragment was mapped by S1 nuclease analysis. Transient assay experiments indicated that this major transcript of the PstI-N fragment was produced by an immediate early gene, named IE-N. The PstI-N fragment alone did not activate expression of p39CAT but was required when IE-1 was present in limiting quantities.

Chromosome Mapping↗

PubMed1995

Isolation and characterization of the gene encoding the Drosophila melanogaster transcriptional elongation factor, TFIIS.

We have characterized a genomic clone encoding the Drosophila melanogaster transcriptional elongation factor, TFIIS. The coding region of the TFIIS gene is interrupted by a short intron. The potential promoter region, deduced from the determination of the transcription start point (tsp), lacks distinct TATAAA or CCAAT box consensus sequences. Southern analysis and the in situ hybridization to chromosomes suggests that it is single-copy gene which is localized to the 35B region on the left arm of the second chromosome.

Animals↗

PubMed1994

Characterization of the gene encoding the iron-sulfur protein subunit of succinate dehydrogenase from Drosophila melanogaster.

The iron-sulfur protein (Ip) subunit of succinate dehydrogenase (and complex II of the electron transport chain) is highly conserved in evolution [Gould et al., Proc. Natl. Acad. Sci. USA 86 (1989) 1934-1938]. We have cloned the Drosophila melanogaster Ip-encoding gene (SdhB) by genomic library screening using the human Ip-encoding cDNA as a probe at low stringency. A 2.7-kb fragment containing SdhB has been sequenced and shown to comprise the entire transcribed region and more than 900 bp of promoter region. The gene contains three exons and two small introns of 272 and 56 nt, respectively, and is transcribed into an mRNA of 1205 nt (plus poly(A) tail). The deduced amino-acid (aa) sequence shows strong similarities with Ip peptides from Escherichia coli, yeasts, plants and mammals, with 100% aa identity around the three Cys clusters which form the non-heme iron-sulfur centers. In situ hybridization on polytene chromosomes maps SdhB to band 42D 1-5 on the right arm of the second chromosome next to the centromere. Developmental and tissue-specific Northern blots show a single transcript of 1.3 kb in all tissues. However, its abundance varies during development and in the major body segments of the adult fly. Pupae have very low levels of transcript, in contrast to larvae. It is most abundant in the adult thorax and low in abdominal tissues.

Amino Acid Sequence↗

PubMed1994

A Drosophila melanogaster homologue of the T-cell oncogene HOX11 localises to a cluster of homeobox genes.

The human homeobox gene HOX11 has been identified at the site of a chromosomal translocation in a subset of T-cell acute leukaemias. In the mouse genome, the hox11 family consists of at least three related genes, each of which possesses a highly conserved homeobox. To assist in elucidating the roles of this gene, a homologue was studied from Drosophila melanogaster. This gene, 311, shares similar identity to all three murine family members and contains the threonine residue in helix 3 of the homeodomain characteristic of the Hox11 family. It maps to a cluster of NK-homeobox genes which function in muscle development. Gene 311 exhibits a similar temporal pattern of expression to the NK genes in this cluster. Therefore, 311 may constitute part of a homeobox cluster in which the genes are both co-ordinately regulated and functionally related.

Amino Acid Sequence↗

PubMed1995

Highly polymorphic repetitive sequences in Rhynchosciara americana genome.

Rhynchosciara americana genomic DNA when digested with EcoR1 or BamH1 presents visible fragments suggestive of repetitive sequences after fractionation on EtBr stained agarose gels. The cloning and molecular analysis of some of these fragments showed a highly polymorphic family of repetitive sequences. These were mapped by in situ hybridization to telomeres and some heterochromatic regions on polytene chromosomes.

Animals↗

PubMed2006

Phylogeny of the corticotropin-releasing factor family of peptides in the metazoa.

The corticotropin-releasing factor (CRF) family of peptides consists of four distinct paralogs found on separate chromosomes in vertebrates. Among invertebrates, the family has been relatively well characterized in the insects where at least 2 or 3 paralogs, a CRF-binding protein ortholog and a CRF receptor variant have been found. The conservation of structure and function of this system in insects imply that the CRF system evolved in ancestral species well before the Precambrian explosion. The CRF family peptides association with diuresis and feeding may have developed early in its evolution. However, CRF's role in the hypothalamo-pituitary-adrenal axis and regulation of the glucocorticoids in association with energy metabolism appears to have developed in the chordate lineage.

Amino Acid Sequence↗

PubMed2002

Drosophila acid DNase is a homolog of mammalian DNase II.

Mammalian DNase II enzymes and the Caenorhabditis elegans homolog NUC-1 have recently been shown to be critically important during engulfment-mediated clearance of DNA. In this report, we describe the cloning and characterization of the gene encoding Drosophila DNase II. Database queries using the C. elegans NUC-1 protein sequence identified a highly homologous open reading frame in Drosophila (CG7780) that could encode a similar enzyme. Analysis of crude protein extracts revealed that wild-type Drosophila contain a potent acid endonuclease activity with cleavage preferences similar to DNase II/NUC1, while the same activity was markedly reduced in an acid DNase hypomorphic mutant line. Furthermore, the pattern of cleavage products generated from an end-labeled substrate by hypomorphic-line extracts was significantly altered in comparison to the pattern generated by wild-type extracts. Sequence analysis of CG7780 DNA and mRNA revealed that the hypomorphic line contains a missense mutation within the coding region of this gene. Additionally, Northern analysis demonstrated that CG7780 expression is normal in the mutant line, which in combination with the lowered/altered enzymatic activity and sequencing data suggested a defect in the CG7780 protein. To conclusively determine if CG7780 encoded the Drosophila equivalent of DNase II/NUC-1, transgenic lines expressing wild-type CG7780 in the mutant background were generated and subsequently shown to complement the mutant phenotype. Our results, therefore, provide compelling evidence that the predicted gene CG7780 encodes Drosophila DNase II (dDNase II), an enzyme related in sequence and activity to mammalian DNase II. Interestingly, overexpression of CG7780 both ubiquitously and in specific tissues failed to elicit any discernable phenotype.

Amino Acid Sequence↗

PubMed1997

A homologue of the 19 kDa signal recognition particle protein locus in Drosophila melanogaster.

A homologue of 19 kDa signal recognition particle locus (SRP19) was cloned and molecularly characterized in Drosophila melanogaster. It is located in the 65F region of the left arm on the third chromosome, approx. 500 bp 5' of the quemao locus. The SRP19 transcript was determined from cDNA clones, Northern blot analysis, and the 5' rapid amplification of cDNA end method. SRP19 was expressed in all the developmental stages of Drosophila. The predicted amino acid sequence (163 aa) shows that SRP19 of Drosophila shares 44%, 29%, 17% and 19% identity with the homologues from human, rice and two yeast species (Saccharomyces and Yarrowia), respectively. The most conserved amino acid residues across these species are located at those sites required for in vitro association with the 7S RNA component of the SRP.

Amino Acid Sequence↗