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PubMed1997

Acquisition and amplification of a testis-expressed autosomal gene, SSL, by the Drosophila Y chromosome.

The acquisition of autosomal fertility genes has been proposed to be an important process in human Y chromosome evolution. For example, the Y-linked fertility factor DAZ (Deleted in Azoospermia) appears to have arisen after the transposition and tandem amplification of the autosomal DAZH gene. The Drosophila melanogaster Y chromosome contains tandemly repeated Su(Ste) units that are thought to affect male fertility as suppressors of the homologous X-linked Stellate repeats. Here we report the detection of a testis-expressed autosomal gene, SSL [Su(Ste)-like], that appears to be an ancestor of the Y-linked Su(Ste) units. SSL encodes a casein kinase 2 (CK2) beta-subunit-like protein. Its putative ORF shares extensive (45%) homology with the genuine beta-subunit of CK2 and retains the conserved C-terminal and Glu/Asp-rich domains that are essential for CK2 holoenzyme regulation. SSL maps within region 60D1-2 of D. melanogaster and D. simulans polytene chromosomes. We present evidence that SSL was derived from the genuine betaCK2 gene by reverse transcription. This event resulted in the loss of the first three introns in the coding region of the SSL ancestor gene. Evolutionary analysis indicates that SSL has evolved under selective pressure at the translational level. Its sequence, especially in the 3' region, is much closer to the Y-linked Su(Ste) tandem repeats than to the betaCK2 gene. These results suggest that the acquisition of testis-specific autosomal genes may be important for the evolution of Drosophila as well as human Y chromosomes.

Amino Acid Sequence↗
PubMed1993

Temperature sensitivity of negative segregation distortion in Drosophila melanogaster.

Previous work has shown that the direction of segregation distortion in the SD (Segregation Distorter) system in Drosophila melanogaster can sometimes be reversed, but this was found only with rather weak distorters and the effect was not large. The present study reports large negative segregation distortion in a strong distorter, SD-72 chromosome. In the presence of a specific X chromosome, supp-X(SD), the proportion, k, of SD-72 chromosomes recovered from the SD-72/cn bw males ranges from 0.99 at 20 degrees to 0.11 at 28.5 degrees, whereas with a standard-X chromosome, k ranges from 0.99 to 0.95 for the same temperature range. The temperature-sensitive period is during spermiogenesis. Using a mating system in which the sperm supply is nearly exhausted, it was shown that the negative distortion at high temperatures is due to an absolute reduction in the number of SD-72 chromosomes and an absolute increase in the number of cn bw chromosomes recovered. After adjusting for non-SD-related temperature effects, the amount of decrease in the number of SD-72 progeny is nearly the same as the amount of increase in the number of cn bw progeny, suggesting that the dysfunction switches from a spermatid carrying one homolog to one carrying the other. Negative distortion requires a radical revision of current hypotheses for the mechanism of segregation distortion and a possible modification of the current model is suggested, based on differential recovery of dysfunction in the two homologs during spermiogenesis.

Alleles↗
PubMed2004

Phylogenetic distribution of TTAGG telomeric repeats in insects.

We examined the presence of TTAGG telomeric repeats in 22 species from 20 insect orders with no or inconclusive information on the telomere composition by single-primer polymerase chain reaction with (TTAGG)6 primers, Southern hybridization of genomic DNAs, and fluorescence in situ hybridization of chromosomes with (TTAGG)n probes. The (TTAGG)n sequence was present in 15 species and absent in 7 species. In a compilation of new and published data, we combined the distribution of (TTAGG)n telomere motif with the insect phylogenetic tree. The pattern of phylogenetic distribution of the TTAGG repeats clearly supported a hypothesis that the sequence was an ancestral motif of insect telomeres but was lost repeatedly during insect evolution. The motif was conserved in the "primitive" apterous insect orders, the Archaeognatha and Zygentoma, in the "lower" Neoptera (Plecoptera, Phasmida, Orthoptera, Blattaria, Mantodea, and Isoptera) with the exception of Dermaptera, and in Paraneoptera (Psocoptera, Thysanoptera, Auchenorrhyncha, and Sternorrhyncha) with the exception of Heteroptera. Surprisingly, the (TTAGG)n motif was not found in the "primitive" pterygotes, the Palaeoptera (Ephemeroptera and Odonata). The Endopterygota were heterogeneous for the occurrence of TTAGG repeats. The motif was conserved in Hymenoptera, Lepidoptera, and Trichoptera but was lost in one clade formed by Diptera, Siphonaptera, and Mecoptera. It was also lost in Raphidioptera, whereas it was present in Megaloptera. In contrast with previous authors, we did not find the motif in Neuroptera. Finally, both TTAGG-positive and TTAGG-negative species were reported in Coleoptera. The repeated losses of TTAGG in different branches of the insect phylogenetic tree and, in particular, in the most successful lineage of insect evolution, the Endopterygota, suggest a backup mechanism in the genome of insects that enabled them frequent evolutionary changes in telomere composition.

Animals↗
PubMed1996

Evolution of the larval cuticle proteins coded by the secondary sex chromosome pair: X2 and neo-Y of Drosophila miranda: II. Comparison at the amino acid sequence level.

The larval cuticle proteins (LCPs) are encoded by a multigene family, Lcp1-4, located at the right arm of the metacentric autosome 2 (2R) in Drosophila melanogaster. Due to a chromosome fusion the Lcp locus of Drosophila miranda is situated on a pair of secondary sex chromosomes, the X2 and neo-Y chromosomes. Comparing the deduced amino acid sequences of the autosomal D. melanogaster loci with the sex-chromosomal loci of D. miranda, we were able to trace the evolution of the Lcp loci with respect to their different chromosomal inheritance. The length of the signal peptide is conserved in all four LCPs, while the size of the mature LCPs varies. Conserved protein motifs became obvious from the alignment, indicating regions of structural and functional importance. Analyzing intra- and interspecific sequence similarities of the Lcp gene families allowed us to reconstruct the phylogeny of the gene cluster. Alignment with cuticle amino acid sequences originating from divergent insect species reveals motifs already present in the primordial insect LCPs. These motifs indicate different levels of constraint acting during the evolution of the LCPs.

Amino Acid Sequence↗
PubMed2005

FlyBase: genes and gene models.

FlyBase (http://flybase.org) is the primary repository of genetic and molecular data of the insect family Drosophilidae. For the most extensively studied species, Drosophila melanogaster, a wide range of data are presented in integrated formats. Data types include mutant phenotypes, molecular characterization of mutant alleles and aberrations, cytological maps, wild-type expression patterns, anatomical images, transgenic constructs and insertions, sequence-level gene models and molecular classification of gene product functions. There is a growing body of data for other Drosophila species; this is expected to increase dramatically over the next year, with the completion of draft-quality genomic sequences of an additional 11 Drosophila species.

Animals↗
PubMed1997

Drosophila DPP2C1, a novel member of the protein phosphatase 2C (PP2C) family.

We report the molecular cloning, chromosome mapping and developmental transcription pattern of a putative serine/threonine protein phosphatase 2C (PP2C), DPP2C1, from Drosophila melanogaster. The 6-kb transcript of this first Drosophila PP2C gene encodes a 1428-aa deduced protein. The DPP2C1 protein contains a approximately 330-aa PP2C-like catalytic domain flanked by extensive N- and C-terminal sequences showing no similarities to other PP2Cs. The dpp2c1 gene maps to 4E1-2 on the X chromosome, 1.5 kb upstream of the ddlc1 gene. Northern blot analyses showed that dpp2c1 transcription is developmentally regulated, accumulating maximally during early (0-6 h) and late (12-24 h) embryogensis. The presented molecular characterisation provides the basis for a genetic dissection of DPP2C1 function.

Amino Acid Sequence↗
PubMed1995

Haploidy and androgenesis in Drosophila.

Adrogenesis, development from paternal but not maternal chromosomes, can be induced to occur in some organisms, including vertebrates, but has only been reported to occur naturally in interspecific hybrids of the Sicilian stick insect. Androgenesis has not been described previously in Drosophila. We now report the recovery of androgenetic offspring from Drosophila melanogaster females mutant for a gene that affects an oocyte- and embryo-specific alpha-tubulin. The androgenetic exceptions are X,X diploid females that develop from haploid embryos and express paternal markers on all 4 chromosomes. The exceptional females arise by fusion of haploid cleavage nuclei or failure of newly replicated haploid chromosomes to segregate, rather than fusion of two inseminating sperm. The frequency of androgenetic offspring is greatly enhanced by a partial loss-of-function mutant of the NCD (nonclaret disjunctional) microtubule motor protein, suggesting that wild-type NCD functions is pronuclear fusion. Diploidization of haploid paternal chromosome complements results in complete genetic homozygosity, which could facilitate studies of gene variation and mutational load in populations.

Animals↗
PubMed1993

Regulation of the sex-specific binding of the maleless dosage compensation protein to the male X chromosome in Drosophila.

In Drosophila, the single male X chromosome is transcribed at twice the rate of a single female X chromosome. This hypertranscription requires the functions of at least four autosomal male-specific lethal genes (msls) and is under the control of the Sex-lethal (Sxl) gene. One of the msls, the maleless (mle) gene, encodes a protein that is associated with the male X chromosome. To investigate how dosage compensation is regulated, we have determined whether Sxl and the other msls are required for mle X chromosome binding. We have found that in females, Sxl functions to prevent mle from binding to the two X chromosomes. Additionally, we have found that mle X chromosome binding requires wild-type msl1, msl2, and msl3 functions. These data support a model whereby the activity of the mle protein is regulated through its association with one or more of the other msl proteins.

Animals↗
PubMed1993

Potential role for a FTZ-F1 steroid receptor superfamily member in the control of Drosophila metamorphosis.

FTZ-F1, a member of the steroid receptor superfamily, has been implicated in the activation of the homeobox segmentation gene fushi tarazu early in Drosophila embryogenesis. We have cloned a developmental isoform of FTZ-F1 and found that it is expressed as a product of the previously identified, midprepupal chromosome puff at 75CD. The 75CD puff occurs in the midst of a period of intense puffing activity that is triggered in response to the steroid hormone ecdysone at the onset of metamorphosis. Indirect immunofluorescent staining for FTZ-F1 on Drosophila polytene chromosomes reveals binding to over 150 chromosomal targets, which include 75CD itself and prominent late prepupal puffs that are predicted to be regulated by midprepupal puff proteins. These results suggest a role for FTZ-F1 as a regulator of insect metamorphosis and underscore the repeated utilization of a regulatory protein for widely separate developmental pathways.

Amino Acid Sequence↗
PubMed1994

Peroxidasin: a novel enzyme-matrix protein of Drosophila development.

Peroxidasin is a novel protein combining peroxidase and extracellular matrix motifs. Hemocytes differentiate early from head mesoderm, make peroxidasin and later phagocytose apoptotic cells. As hemocytes spread throughout the embryo, they synthesize extracellular matrix and peroxidasin, incorporating it into completed basement membranes. Cultured cells secrete peroxidasin; it occurs in larvae and adults. Each 1512 residue chain of the three-armed, disulfide-linked homotrimer combines a peroxidase domain with six leucine-rich regions, four Ig loops, a thrombospondin/procollagen homology and an amphipathic alpha-helix. The peroxidase domain is homologous with human myeloperoxidase and eosinophil peroxidase. This heme protein catalyzes H2O2-driven radioiodinations, oxidations and formation of dityrosine. We propose that peroxidasin functions uniquely in extracellular matrix consolidation, phagocytosis and defense.

Amino Acid Sequence↗
PubMed1997

Molecular organization of the glutathione reductase gene in Drosophila melanogaster.

Glutathione reductase catalyzes the conversion of the oxidized form of glutathione to regenerate reduced glutathione, which acts as a versatile intracellular reductant. The present study provides initial characterization of the glutathione reductase gene in Drosophila melanogaster and its response to experimentally induced oxidative stress. Drosophila cDNA clones were isolated, based on cross-hybridization to the Musca domestica glutathione reductase cDNA. Genomic clones were isolated by cross-hybridization with the Drosophila cDNA as hybridization probe. Northern analysis of adult Drosophila poly(A)+ RNA, utilizing the Drosophila cDNA probe, revealed a hybridization signal in the 2-kb range. The entire sequence of one cDNA was determined. In addition to a coding domain of 1431 bases, the sequence included 206 bases upstream of a putative start codon and 355 bases downstream of a putative stop codon. Based on the cDNA sequence, the 476 amino acid sequence of the Drosophila glutathione reductase gene was deduced and was found to have extensive similarities with the glutathione reductase gene from other species. Gene mapping of a 13-kb genomic fragment revealed that the glutathione reductase gene consists of at least two exons spanning approximately 5 kb. A first exon contains sequence for only the first 5 amino acids and the first base of the sixth and appears to be separated by a ca. 2.5-kb intron from the remainder of the coding region, which is confined to <2 kb. The Drosophila glutathione reductase is single copy and its cytogenetic position, as determined by in situ hybridization, is 7D-E on the X chromosome. mRNA levels of glutathione reductase, measured by RT-PCR, increased in response to exposure to 100% ambient oxygen by almost twofold and administration of paraquat by greater than threefold. Exposure of flies to hyperoxia also induced a 60% increase in the activity of glutathione reductase and augmented the concentration of total glutathione by ca. 40% following an initial drop. The present study, besides providing an initial molecular characterization of the glutathione reductase gene in Drosophila, demonstrates its dynamic involvement in response to experimentally induced oxidative stress.

Amino Acid Sequence↗
PubMed1993

Molecular identification of onchocerciasis vector sibling species in black flies (Diptera: Simuliidae).

A number of sibling species in the Simulium damnosum species complex transmit River Blindness (onchocerciasis) in tropical Africa. Black fly sibling species can be reliably recognized only through analysis of the larval polytene chromosomes. The routine, unambiguous assignment of the potentially disease-transmitting adult females to a particular species is virtually impossible. Two molecular assays to identify the sibling species of biting female flies are presented. The first relies on PCR-mediated amplification of internal transcribed spacers of the nuclear rDNA loci while the second involves immunoblotting of silk proteins which are expressed in both larvae and adult females. Both assays yield sibling-specific size markers that can be used to identify the sibling species of biting adult females. To illustrate the use of these assays, a molecular characterization is given for two S. damnosum siblings (squamosum, sirbanum) collected from cytologically verified populations, and a partial characterization of a third sibling (damnosum s. str.) found as a contaminant in these samples.

Animals↗
PubMed1999

Hedgehog signal transduction: from flies to vertebrates.

The patterning and morphogenesis of multicellular organisms require a complex interplay of inductive signals which control proliferation, growth arrest, and differentiation of different cell types. A number of such signaling molecules have been identified in vertebrates and invertebrates. The molecular dissection of these pathways demonstrated that in vertebrates, mutations or abnormals function of these signaling pathways were often associated with developmental disorders and cancer formation. The Hedgehog (Hh) family of secreted proteins provides a perfect example of such signaling proteins. In the following review, we will not discuss in detail the role of Hh as a morphogen, but rather focus on its signal transduction pathway and its role in various human disorders.

Chromosome Aberrations↗
PubMed1993

Cloning, analysis, and chromosomal localization of Notch-1, a mouse homolog of Drosophila Notch.

The Notch gene of Drosophila encodes a large transmembrane protein involved in cell-cell interactions and cell fate decisions in the Drosophila embryo. We report here the isolation of cDNA clones encompassing the full-length coding sequence of Notch-1, a mouse homolog of Drosophila Notch. The predicted amino acid sequence of the Notch-1 protein retains all of the conserved amino acid motifs of Notch and the other vertebrate Notch homologs. The cDNA sequence predicts a 2531-amino-acid protein containing a signal peptide, 36 epidermal growth factor-like repeats, 3 Notch/lin-12 repeats, a transmembrane domain, and 6 cdc10/ankyrin repeats. The Notch-1 gene was localized to the proximal portion of mouse chromosome 2 by mapping with an interspecific backcross panel.

Amino Acid Sequence↗
PubMed1996

Isolation of a gene (DLG3) encoding a second member of the discs-large family on chromosome 17q12-q21.

The discs-large family is a collection of proteins that have a common structural organization and are thought to be involved in signal transduction and mediating protein-protein interactions at the cytoplasmic surface of the cell membrane. The defining member of this group of proteins is the gene product of the Drosophila lethal (1) discs large (dlg) 1 locus, which was originally identified by the analysis of recessive lethal mutants. Germline mutations in dlg result in loss of apical-basolateral polarity, disruption of normal cell-cell adhesion, and neoplastic overgrowth of the imaginal disc epithelium. We have isolated and characterized a novel human gene, DLG3, that encodes a new member of the discs-large family of proteins. The putative DLG3 gene product has a molecular weight of 66 kDa and contains a discs-large homologous region, a src oncogene homology motif 3, and a domain with homology to guanylate kinase. The DLG3 gene is located on chromosome 17, in the same segment, 17q12-q21, as the related gene, DLG2. The products of the DLG2 and DLG3 genes show 36% identity and 58% similarity to each other, and both show nearly 60% sequence similarity to p55, an erythroid phosphoprotein that is a component of the red cell membrane. We suggest that p55, DLG2, and DLG3 are closely related members of a gene family, whose protein products have a common structural organization and probably a similar function.

Amino Acid Sequence↗
PubMed1998

Chromosomal mapping of human armadillo genes belonging to the p120(ctn)/plakophilin subfamily.

Armadillo-like proteins are characterized by a series of armadillo repeats that are typically 42 to 45 amino acids in length. Three major subfamilies of Armadillo-like proteins can be distinguished on the basis of their number of repeats, their overall sequence similarity, and dispersion of the repeats throughout the protein. One of these is the p120(ctn)/plakophilin subfamily, which contains at least six members. We mapped the corresponding human genes by PCR on a monochromosomal cell hybrid mapping panel and by fluorescence in situ hybridization. The gene for plakophilin-1 (PKP1) was located at 1q32, the plakophilin-2 gene (PKP2) was located at 12p13, while the gene for p0071 was located at 2q23-q31. We confirmed the chromosomal localization of the p120(ctn) gene (CTNND1) at 11q11, the ARVCF gene at 22q11, and the delta-catenin/NPRAP gene (CTNND2) at 5p15. Although some of the Armadillo proteins are highly related to one another, the corresponding genes are dispersed throughout the human genome.

Armadillo Domain Proteins↗
PubMed1993

A new member of the balbiani ring multigene family in the dipteran Chironomus tentans consists of a single-copy version of a unit repeated in other gene family members.

The known Balbiani ring (BR) multigene family members in the dipteran Chironomus tentans encode salivary gland secretory proteins in the size range between 38 and 1,000 kDa. The proteins interact to form protein fibers used by the aquatic larvae to spin feeding and protective larval tubes or pupation tubes. Here, we describe a new BR multigene family member, the sp17 gene, which codes for an 89-amino-acid-long protein with a relative mobility of 17k. The gene has a high content of charged amino acid residues and consists of two structurally different halves. Five regularly spaced cysteine codons are present in the 5' half while the 3' half contains five proline codons. These two different halves exhibit similarities to the C and SR regions, respectively, which form the tandemly repeated units in the about 40-kb-long BR genes and which also, in different versions, are the building blocks of all genes in the BR multigene family. In this multigene family, encoding interacting structural proteins, the long BR genes with their 125-150 tandemly arranged repeat units as well as the short sp17 gene with its single-copy version of such a repeat unit, have therefore evolved from a common ancestor.

Amino Acid Sequence↗