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At least 127 records · Page 7Linked to original sources

PubMed2003

Characterization and transcriptional profiles of three Spodoptera frugiperda genes encoding cysteine-rich peptides. A new class of defensin-like genes from lepidopteran insects?

The present work describes sequence and transcription of three Spodoptera frugiperda genes encoding 6-cysteine-rich peptides. Sequence alignments indicate that the predicted peptides belong to the insect defensin family, although phylogenetic analyses suggest they form a cluster distinct from that of other neopteran insect defensins. The three genes were identified in a non-immune-challenged Sf9 cells cDNA (DNA complementary to RNA) library (Landais et al., Bioinformatics, in press) and were named spodoptericin, Sf-gallerimycin and Sf-cobatoxin. Spodoptericin is a novel defensin-like gene that appears to be weakly up-regulated following injection of bacteria and fungi. Interestingly, no sequence motif clearly homologous to cis regulatory element involved in the regulation of antimicrobial genes was found. An homologue of the spodoptericin gene was identified in the SilkBase Bombyx mori cDNA library. Sf-gallerimycin is related to the Galleria mellonella gallerimycin gene and is induced after immune challenge by injection of bacteria in the larval fat body as well as in hemocytes. In silico analysis of the sequence upstream from the cDNA reveals the presence of at least one motif homologous to a nuclear factor kappaB (NF-kappaB) binding site. Finally, Sf-cobatoxin is related to the G. mellonella cobatoxin-like gene. Despite high levels of constitutive expression compared to the two previous genes, transcription of Sf-cobatoxin is increased after immune, in particular, bacterial challenge. We therefore confirm that these three genes encode potential candidate molecules involved in S. frugiperda innate humoral response.

Amino Acid Sequence↗

PubMed2004

Polydnavirus genes and genomes: emerging gene families and new insights into polydnavirus replication.

Polydnavirus genome sequencing is providing new insights into viral genome organization and viral gene function. Sequence analyses demonstrate that the genomes of these viral mutualists are largely noncoding but maintain genes and gene families that are unrelated to other viral genes. Interestingly, these organizational patterns in polydnavirus genomes are evident in both the bracovirus and ichnovirus genera, even though these two genera are evolutionarily unrelated. The identity and function of some polydnavirus gene families are considered with some functions experimentally supported and others implied by homology relationships with known insect genes. The evidence relative to polydnavirus origins and evolution is considered but remains an area of speculation. However, sequencing of these viral genomes has been informative and provides opportunities for productive investigation of these unusual mutualistic insect viruses.

Animals↗

PubMed2026

First complete mitochondrial genome of Uzelothrips scabrosus (Thysanoptera: Uzelothripidae) provides insights into gene rearrangements and phylogenetic position within Terebrantia.

The family Uzelothripidae is represented by a single genus Uzelothrips and can be distinguished from others by the presence of whip-like antennae, a circular ventral sensorium on antennal segment III, a well-developed tentorium, and a membranous ovipositor. Here, we generated the first complete mitochondrial genome of Uzelothrips scabrosus (15,674 bp) using next-generation sequencing to explore the gene rearrangements and phylogenetic relationships. It consists of 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and two putative control regions. The genome exhibits strong AT bias (71.35%) with negative AT and GC skew. Codon usage analyses indicate a strong bias towards A/U-ending codons and influenced by both natural selection and mutation pressure. All PCGs were under purifying selection, with cox1 being the most conserved and nad4L the most variable. The gene order of the family Uzelothripidae is highly rearranged compared to the ancestral insect gene order. Comparative analysis revealed that gene block B was the most widely conserved, whereas the remaining gene blocks exhibited family or lineage-specific conservation patterns, reflecting extensive mitochondrial gene rearrangements during the evolution of the Thysanoptera. Moreover, 228 synapomorphic and 68 autapomorphic gene boundaries were identified across thysanopteran mitogenomes. Phylogenies indicated that the family Uzelothripidae is in a sister relationship with Stenurothripidae, and the Uzelothripidae + Stenurothripidae clade is sister to Thripidae. This study provides the first mitogenomic insights into Uzelothripidae and highlights the need for broader taxon sampling and nuclear genomic data to resolve deep evolutionary relationships within Thysanoptera.

Comparative analysis↗

PubMed2005

Expression of sarcotoxin IA gene via a root-specific tob promoter enhanced host resistance against parasitic weeds in tomato plants.

We have developed a simple genetic engineering strategy for conferring resistance against parasitic weeds on host plants. Transgenic tomato plants expressing the sarcotoxin IA gene were grown either in polyethylene bags (PE) or in pots inoculated with Orobanche aegyptiaca seeds. The results indicate that transgenic plants exhibited strong inhibition of parasite growth and significantly increased yield as compared with non-transgenic ones. In both PE and pot systems most of the parasite tubercles attached to the transgenic root plants turned necrotic and developed abnormally. Integration and expression of the gene were confirmed by Southern blot, RT-PCR and Western blot analysis. Our results indicate that the insect gene produced in the plant cells was selectively toxic to the parasite and non-toxic to the host plant.

Gene Expression↗

PubMed1996

Structure of the Bombyx sorbitol dehydrogenase gene: a possible alternative use of the promoter.

In an initial effort to understand the molecular mechanism of how low temperature induces sorbitol dehydrogenase gene expression in diapause eggs of the silkworm, the sorbitol dehydrogenase gene was isolated from a Bombyx genomic library using a cDNA encoding the Bombyx homologue of mammalian sorbitol dehydrogenase as a probe. The gene extended for about 10 kb, consisting of eight exons and seven introns. Four TATA motifs were found in the 5' upstream region of the gene, without CCAAT. AATTAA, instead of AATAAA, was localized in the upstream region of the polyadenylation site. Although a single copy of this gene was present per haploid genome, 1.2 kb and 1.1 kb transcripts were found from yolk cells in diapause eggs and from larval fat-body cells, respectively. The two major transcription initiation sites corresponding to both transcripts were localized at 355 and 226 base pairs upstream from the transition start site, indicating an alternative use of promoter. The 5'-upstream region of the gene contained a consensus sequence, TGA(A/T)AA(A/G/T), that has been found in insect genes expressed mainly in larval and pupal fat bodies. It also contained three kinds of sequences similar to cis-elements recognized by members of the steroid receptor superfamily, such as chicken ovalbumin upstream promoter transcription factor (COUP-TF)/Drosophila Seven up (SVP), Drosophila hormone receptor 39 (DHR39) and Bombyx fushi tarazu transcriptional factor 1 (BmFTZ-F1).

Alternative Splicing↗

PubMed2005

The coevolution of insect muscle TpnT and TpnI gene isoforms.

In bilaterians, the main regulator of muscle contraction is the troponin (Tpn) complex, comprising three closely interacting subunits (C, T, and I). To understand how evolutionary forces drive molecular change in protein complexes, we have compared the gene structures and expression patterns of Tpn genes in insects. In this class, while TpnC is encoded by multiple genes, TpnT and TpnI are encoded by single genes. Their isoform expression pattern is highly conserved within the Drosophilidae, and single orthologous genes were identified in the sequenced genomes of Drosophila pseudoobscura, Anopheles gambiae, and Apis mellifera. Apis expression patterns also support the equivalence of their exon organization throughout holometabolous insects. All TpnT genes include a previously unidentified indirect flight muscle (IFM)-specific exon (10A) that has evolved an expression pattern similar to that of exon 9 in TpnI. Thus, expression patterns, sequence evolution trends, and structural data indicate that Tpn genes and their isoforms have coevolved, building species- and muscle-specific troponin complexes. Furthermore, a clear case can be made for independent evolution of the IFM-specific isoforms containing alanine/proline-rich sequences. Dipteran genomes contain one tropomyosin gene that encodes one or two high-molecular weight isoforms (TmH) incorporating APPAEGA-rich sequences, specifically expressed in IFM. Corresponding exons do not exist in the Apis tropomyosin gene, but equivalent sequences occur in a high-molecular weight Apis IFM-specific TpnI isoform (TnH). Overall, our approach to comparatively analyze supramolecular complexes reveals coevolutionary trends not only in gene families but in isoforms generated by alternative splicing.

Amino Acid Sequence↗

PubMed1993

An apoptosis-inhibiting baculovirus gene with a zinc finger-like motif.

Spodoptera frugiperda SF-21 cells infected with Autographa californica nuclear polyhedrosis virus mutants which lack a functional p35 gene undergo apoptosis, a type of programmed cell death. To identify p35-homologous genes in other baculoviruses, A. californica nuclear polyhedrosis virus DNA containing a deletion in p35 was cotransfected into SF-21 cells along with genomic DNAs from other baculoviruses. One of the viral DNAs which were able to rescue wild-type infection was from Cydia pomonella granulosis virus (CpGV). The CpGV gene responsible for the effect was mapped to a 1.6-kb SalI-SstI subclone of the SalI B fragment of CpGV. The sequence of the SalI-SstI subclone revealed an open reading frame capable of encoding a polypeptide of 31 kDa which was sufficient to rescue wild-type infection; this gene was thus called iap (inhibitor of apoptosis). The predicted sequence of the IAP polypeptide exhibited no significant homology to P35 but contained a zinc finger-like motif which is also found in other genes with the potential to regulate apoptosis, including several mammalian proto-oncogenes and two insect genes involved in embryonic development. In the context of the viral genome, both iap and p35 were able to block apoptosis induced by actinomycin D, indicating that these genes act by blocking cellular apoptosis rather than by preventing viral stimulation of apoptosis. Several independent recombinant viruses derived from cotransfections with either the entire CpGV genome or the 1.6-kb subclone were characterized.

Amino Acid Sequence↗

PubMed2004

The GH/IGF-I axis and longevity.

Several converging lines of evidence obtained over the last years in a wide variety of experimental model organisms suggest that the ageing process is regulated by genes that encode proteins from the somatotroph axis: longevity genes like daf-2, which were identified using mutant Caenorhabditis elegans strains, turned out to be orthologues of the mammalian genes encoding insulin-like signalling cascade proteins. Transgenic flies with mutations in the corresponding insect genes showed a similar pattern of increased lifespan. Finally, mice with spontaneous mutations leading to pituitary hormone deficiency significantly outlived controls. While these and other genetic models suggest that the downregulation of the somatotroph axis can slow the ageing process, other results from studies using pharmacological administration of growth hormone suggest that such stimulating treatment can restore some of the phenotypic traits associated with youth. To better understand the role of the insulin-like receptors in mammalian lifespan regulation and ageing, we explored the phenotype of heterozygous IGF-I receptor (IGF1R) knockout mice. Compared with control littermates these mutants live longer without any obvious impairment of their health and physiology, except a reduced glucose tolerance that we observed in males. These IGF1R(+/-) mutants were also more resistant to oxidative stress in vivo, and we identified a possible molecular pathway linking underphosphorylation of IGF-I receptors to the lack of activation of p66Shc, a protein capable of increasing resistance to oxidative stress through regulation of a set of downstream genes. These and other results suggest that in mammals too, lifespan can be increased by continuous, long-term downregulation of IGF signalling. Since growth hormone administration normally stimulates IGF production in tissues, the question arises whether the beneficial effects of GH, as reported by others, could be IGF independent. This hypothesis can be addressed, for example, by adequately combining existing transgenic mouse models.

Aging↗

PubMed1997

Developmental regulation of the Drosophila Tropomyosin I (TmI) gene is controlled by a muscle activator enhancer region that contains multiple cis-elements and binding sites for multiple proteins.

Developmental gene regulation in vertebrate somatic muscles involves the cooperative interaction of MEF2 (myocyte-specific enhancer-binding factor 2) and members of the b-HLH (basic helix-loop-helix) family of myogenic factors. Until recently, however, nothing was know about the factors that control the developmental regulation of muscle genes during embryogenesis in Drosophila. The Drosophila Tropomyosin I (TmI) gene contains a proximal and distal muscle enhancer within the first intron that regulates its expression in embryonic/larval and adult muscles. We have recently shown that the 355-bp proximal enhancer contains a binding site for the Drosophila homologue of vertebrate MEF2 and that MEF2 acts cooperatively with a basal level muscle activator region to direct high level muscle expression in transgenic flies. The 92-bp muscle activator region, however, does not contain any consensus E-box (CANNTG) binding site sequences for b-HLH myogenic factors, suggesting the MEF2 may interact with other factors to regulate muscle genes in Drosophila. In this study we have used mutation analysis and germ-line transformation to analyze cis-acting elements within the muscle activator region that regulate its expression in transgenic flies. We have identified a 71-bp region that is sufficient for low basal level temporal- and muscle-specific expression in the embryo, larva, and adult. Substitution mutations within the muscle activator region have identified several cis-element regions spanning 60-bp that are required for either full or partial muscle activator function. An analysis of proteins that bind to this region by gel mobility shift assay and copper nuclease footprinting has allowed us to identify the sites in this region at which multiple proteins complex and interact. We propose that these cis-elements and the proteins that they bind regulate muscle activator function and together with MEF2 are capable of regulating high level muscle expression.

Animals↗

PubMed1998

cis-Acting sequences controlling the adult-specific transcription pattern of the Drosophila affinidisjuncta Adh gene.

The cis-acting sequences required for the adult-specific expression pattern of the alcohol dehydrogenase (Adh) gene of the Hawaiian picture-winged fruit fly, Drosophila affinidisjuncta were analyzed by germline transformation. Normally this gene produces two developmentally regulated transcripts. The upstream (distal) promoter produces a distal transcript, which makes up about 80% of the total in adults, while the downstream (proximal) promoter produces a corresponding proximal transcript, which accounts for the remainder. Previously constructed genes lacking regions corresponding to regulatory elements within the Drosophila melanogaster Adh gene or regions known to be required for full expression of the D. affinidisjuncta Adh gene in larvae were analyzed by introduction into the germline of D. melanogaster followed by RNase-protection analysis of RNA levels. In addition, to test a model of preferential promoter utilization by which transcription at the proximal promoter is inhibited by transcription initiated at the upstream distal promoter, a construction lacking the distal promoter was analyzed. Sequences homologous to the adult enhancer of the Adh gene of D. melanogaster appear to play a similar role in the D. affinidisjuncta gene. In contrast to what has been reported for other Drosophila Adh genes, this and some other regulatory elements are shared by the two promoters of the D. affinidisjuncta gene. Taken together, the results favor a model of stage-specific switching between the two promoters of the D. affinidisjuncta gene that involves competition for limiting components stimulating transcription, rather than interference by read-through from the upstream promoter.

Alcohol Dehydrogenase↗

PubMed1997

Fish are like flies are like frogs: conservation of dorsal-ventral patterning mechanisms.

Genetic analysis of Drosophila has shown that a morphogenetic gradient of the Transforming Growth Factor-beta family member dpp patterns the embryonic dorsal-ventral axis. Molecular and embryological evidence from Xenopus has strongly suggested a similar role for Bmp-4, the dpp homolog, in patterning the dorsal-ventral axis of chordates. A recent report has now identified mutations in two genes, dino and swirl, that disrupt dorsal-ventral patterning in the zebrafish Danio rerio. Characterization of these mutations parallels findings from Drosophila, thus establishing a genetic framework for the analysis of dorsal-ventral patterning in a vertebrate.

Animals↗

PubMed1995

Drosophila Polycomb-group regulated chromatin inhibits the accessibility of a trans-activator to its target DNA.

The genes of the Polycomb-group (Pc-G) are responsible for maintaining the inactive expression state of homeotic genes. They act through specific cis-regulatory DNA elements termed PREs (Pc-G Response Elements). Multimeric complexes containing the Pc-G proteins are thought to induce heterochromatin-like structures, which stably and heritably inactivate transcription. We have tested the functional role of the FAB fragment, a PRE of the bithorax complex. We find that this element behaves as an orientation dependent silencer, capable of inducing mosaic gene expression on neighboring genes. Transgenic fly lines were constructed containing a PRE adjacent to a reporter gene inducible by the yeast GAL4 trans-activator. The competition between the activator and Pc-G-containing chromatin was visualized on polytene chromosomes using immunocytochemistry. The Pc-G protein Polycomb and GAL4 have mutually exclusive binding patterns, supporting the notion that Pc-G-induced chromatin structures can prevent activators from binding to their target sequences. However, this antagonistic function can be overcome by high doses of GAL4, even in the absence of DNA replication.

Animals↗

PubMed1996

Production in Escherichia of moricin, a novel type antibacterial peptide from the silkworm, Bombyx mori.

Moricin is a novel type antibacterial peptide recently isolated from the silkworm, Bombyx mori. Two foreign gene expression systems in Escherichia coli were employed to obtain a large amount of the peptide for further characterization. An artificial moricin gene was chemically synthesized and inserted into two expression vectors, pXa1 and pMAL-c2. The recombinant moricin was efficiently produced in E. coli as fusion proteins and released by chemical cleavage with cyanogen bromide or o-iodosobenzoic acid. Eleven milligrams of pure recombinant moricin was obtained from 2 L of E. coli culture. The primary structure and molecular mass of the purified recombinant moricin was the same as those of the natural moricin. In addition, the antibacterial activity of the recombinant moricin against E. coli and Staphylococcus aureus was comparable to that of the natural moricin.

Amino Acid Sequence↗

PubMedDate not supplied

The role of transcriptional activation in the function of the Drosophila myb gene.

Vertebrate myb genes encode DNA-binding proteins that regulate transcription and have been implicated in regulation of cell proliferation, differentiation, and apoptosis. We have demonstrated that the single myb gene in Drosophila melanogaster, Dm myb, is required for the G(2)/M transition of the cell cycle and for suppression of endoreduplication. Recently, it has become apparent that the family of proteins containing Myb-related DNA-binding domains is much larger than originally believed and that the biochemical properties and functions of these proteins are diverse. We undertook studies to characterize the biochemical properties of the Drosophila Myb protein (DMyb). We now provide evidence that in addition to having homology with the vertebrate Myb proteins, the Drosophila Myb protein (DMyb) shares its biochemical properties. DMyb binds to a similar consensus sequence and activates transcription from a reporter construct regulated by vertebrate Myb proteins. We also show that DMyb proteins carrying mutations corresponding to previously isolated mutant alleles of Dm myb are less active as transcriptional activators than wild-type DMyb, indicating that a decrease in transcriptional activation ability is likely to cause the mutant phenotypes.

Animals↗

PubMed1999

Drosophila Src42A is a negative regulator of RTK signaling.

The Src family of nonreceptor tyrosine kinases has been implicated in many signal transduction pathways. However, due to a possible functional redundancy in vertebrates, there is no genetic loss-of-function evidence that any individual Src family member has a crucial role for receptor tyrosine kinase (RTK) signaling. Here we show that an extragenic suppressor of Raf, Su(Raf)1, encodes a Drosophila Src family gene Src42A. Characterization of Src42A mutations shows that Src42A acts independent of Ras1 and that it is, unexpectedly, a negative regulator of RTK signaling. Our study provides the first evidence that Src42A defines a negative regulatory pathway parallel to Ras1 in the RTK signaling cascade. A possible model for Src42A function is discussed.

Alleles↗

PubMed1994

The dominant Drop eye mutations of Drosophila melanogaster define two loci implicated in normal eye development.

The three existing dominant gain-of-function Drop alleles, Dr1, DrMio and DrWe, previously assumed to define a single locus, severely disrupt eye development. Genetic analysis of ethylmethanesulphonate (EMS) and irradiation-induced revertants revealed that the Drop mutations define two loci: the Drop locus, which is defined by the Dr1 and DrMio mutants, and a separate locus defined by the DrWe mutation, which has been renamed Wedge. The majority of the Dr1 and DrMio revertants are embryonic lethal in trans, mutant embryos exhibiting trachea that fail to join the Filzkörper, thus revealing a role for the Drop gene in embryogenesis. Clonal analysis of lethal revertant alleles suggests a role for both genes in eye development. In the Drop homozygous mutant clones, the outer photoreceptor cells R1-R6 develop aberrantly. Wedge, however, is not required by the developing photoreceptor cells but its absence does disrupt normal ommatidial alignment. Although the Drop and nearby string loci were shown to be genetically distinct, both Dr1 and DrMio were found to interact in trans with lesions at the string locus, causing loss and derangement of bristles and loss of neuromuscular coordination.

Alleles↗

PubMed1997

A trans-acting modifier causing extensive overexpression of genes in Drosophila melanogaster.

A modified P element-induced mutation at cytological position 47A11-12 on chromosome 2 of Drosophila melanogaster inversely alters the expression of several genes examined. In addition, the effect is nearly exponential in some developmental stages for five of the eleven genes tested (white, brown, scarlet, rudimentary and vermilion). Interestingly, the exponential overexpression of the transcripts leads to a sexually dimorphic effect, with female levels being greater. The white allele specificity analysis and the lack of response of an Alcohol dehydrogenase promoter-white reporter fusion construct suggest that the 5' regulatory sequences of white are required for the response. Because the cases of extreme overexpression are more prominent in females than males, the locus is termed Ultra female overexpression (Ufo). Ufo revertants have no discernible effect on the transcript levels, indicating that the mutation is responsible for the modulation of the tested genes. Regulatory genes such as Ufo may contribute to the wide fluctuations in gene expression between tissues and stages of development.

ATP-Binding Cassette Transporters↗

PubMed1994

Cell cycle progression in the developing Drosophila eye: roughex encodes a novel protein required for the establishment of G1.

The onset of pattern formation in the developing Drosophila eye is marked by the simultaneous synchronization of all cells in the G1 phase of the cell cycle. These cells will then either commit to another round of cell division or differentiate into neurons. Although cell cycle synchronization occurs in roughex (rux) mutants, cells circumvent G1 and all cells enter S phase, including cells that would normally differentiate. This leads to defects in early steps of pattern formation and cell fate determination. rux is suppressed by mutations in genes that promote cell cycle progression (i.e., cyclin A and string) and enhanced by mutations in genes that promote differentiation (i.e., Ras1 and Star). rux encodes a novel protein of 335 amino acids. We propose that rux functions as a negative regulator of G1 progression in the developing eye.

Amino Acid Sequence↗