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At least 919 records · Page 51Linked to original sources
PubMed2004

Tribolium castaneum twist: gastrulation and mesoderm formation in a short-germ beetle.

Mesoderm formation has been extensively analyzed in the long-germ insect Drosophila melanogaster. In Drosophila, both the invagination and specification of the mesoderm is controlled by twist. Here we present a detailed description of mesoderm formation and twist regulation for the short-germ beetle Tribolium castaneum. In contrast to Drosophila, (1) the presumptive mesodermal cells of Tribolium are part of a mitotic domain and divide prior to ventral furrow formation, (2) ventral furrow formation progresses from posterior to anterior, (3) the number of cell layers within the furrow changes from multilayered in caudal to single layered in cephalic regions, and (4) there is a continuous production of mesodermal cells after gastrulation as new segments arise from the posterior growth zone. Tribolium twist (Tc-twist) is initially expressed in all presumptive mesodermal cells; however, after invagination, expression is maintained only in particular locations, which include the anterior compartments of the cephalic segments and a patch of cells at the posterior rim of the growth zone. The growth zone is multilayered with its inner cell layer being continuous with the mesoderm of the newly forming segments where twist expression is re-initiated anterior to the emerging engrailed stripes. A genomic region of Tc-twist was identified which drives ventral expression of a reporter construct in Drosophila. The expression of this Tc-twist construct in the background of Drosophila maternal mutations suggests that the dorsoventral system regulates Tc-twist, but that differences exist in regulation of the Dm-twist and Tc-twist genes by the terminal system.

Amino Acid Motifs↗
PubMed2003

Cloning of cytochrome P450, CYP6P5, and CYP6AA2 from Anopheles minimus resistant to deltamethrin.

Two new genes in the cytochrome P450 (CYP6) family 6 with complete coding sequences were cloned and sequenced from deltamethrin-resistant Anopheles minimus, a major malaria vector in Thailand. CYP6P5 encodes a protein of 508 amino acids, while CYP6AA2 contains 505 residues. Each encoded protein contains a hydrophobic N-terminal region and a highly conserved heme-binding region typical of P450s. Alignments of deduced amino acid sequences with other insect P450 genes indicate a high degree of identity to insect CYP6 genes. Comparative mRNA expression studies using semi-quantitative RT-PCR analysis indicated that the relative amount of CYP6AA2 transcript was greater in the deltamethrin-resistant An. minimus compared to the susceptible strain. The expression of CYP6AA2 in deltamethrin-resistant mosquitoes is associated with development of deltamethrin resistance in An. minimus mosquito. The CYP6P5 transcript is equally expressed in both resistant and susceptible mosquitoes.

Amino Acid Sequence↗
PubMed2006

Expression and down-regulation of cytochrome P450 genes of the CYP4 family by ecdysteroid agonists in Spodoptera littoralis and Drosophila melanogaster.

The function of CYP4 genes in insects is poorly understood. Some CYP genes are up-regulated by ecdysteroids and a number of Cyp4 genes in Drosophila melanogaster have been shown by microarray to be down-regulated when the ecdysteroid titre is high, suggesting hormonal regulation. Here, we report the utilization of certain cloned CYP4 cDNAs/fragments to probe their developmental/tissue expression in the Lepidopteran, Spodoptera littoralis, including the effects of ecdysteroid receptor agonists (bis-acyl hydrazines). CYP4L8 is expressed essentially throughout the final larval instar of S. littoralis and, together with CYP4M12, is down-regulated by agonist. Furthermore, expression of these genes occurs in midgut, but is undetectable in brain, fat body, and integument. Similarly, in D. melanogaster, Cyp4ac1, Cyp4ac3, Cyp4ad1 and Cyp4d1 gene expression is drastically down-regulated by ecdysteroid agonist. The significance of the results is discussed in relation to the plausible functions of the CYP4 genes in Lepidoptera and mechanisms of down-regulation.

Animals↗
PubMed2025

A deep insight into the sialome of the house fly, Musca domestica, infected with the salivary gland hypertrophy virus (MdSGHV).

The house fly, Musca domestica, serves as a mechanical vector for numerous pathogens, posing a significant risk to human and animal health. More than two decades ago, the Musca domestica salivary gland hypertrophy virus (MdSGHV) was discovered, infecting both males and females flies and disrupting mating and the reproductive process. While MdSGHV can infect various tissues, its primary replication site is the house fly salivary gland. It is well established that arthropod salivary glands play an important role not only in acquiring food but also in transmitting pathogens. Therefore, understanding the composition of vector salivary glands and the interactions between vector and pathogen components is essential for developing future control strategies. To this end, we conducted a comprehensive RNA-sequencing of salivary glands from both infected and non-infected house flies. Our analysis identified a total of 6,410 putative sequences, with 6,309 originating from M. domestica and 101 from the MdSGHV, categorized into 25 functional groups. Furthermore, differential expression analysis between infected and non-infected salivary glands revealed 2,852 significantly modulated transcripts, highlighting profound transcriptional changes triggered by MdSGHV infection. Overall, these findings not only deepen our understanding of the composition of M. domestica salivary glands but also provide valuable insight into the virus-vector interaction, which could serve as a model to understand other medically relevant interactions.

Salivary Glands↗
PubMed2000

The clock gene period of the housefly, Musca domestica, rescues behavioral rhythmicity in Drosophila melanogaster. Evidence for intermolecular coevolution?

In Drosophila, the clock gene period (per), is an integral component of the circadian clock and acts via a negative autoregulatory feedback loop. Comparative analyses of per genes in insects and mammals have revealed that they may function in similar ways. However in the giant silkmoth, Antheraea pernyi, per expression and that of the partner gene, tim, is not consistent with the negative feedback role. As an initial step in developing an alternative dipteran model to Drosophila, we have identified the per orthologue in the housefly, Musca domestica. The Musca per sequence highlights a pattern of conservation and divergence similar to other insect per genes. The PAS dimerization domain shows an unexpected phylogenetic relationship in comparison with the corresponding region of other Drosophila species, and this appears to correlate with a functional assay of the Musca per transgene in Drosophila melanogaster per-mutant hosts. A simple hypothesis based on the coevolution of the PERIOD and TIMELESS proteins with respect to the PER PAS domain can explain the behavioral data gathered from transformants.

Amino Acid Sequence↗
PubMed1999

Structure and expression of tandemly duplicated xanthine dehydrogenase genes of the silkworm (Bombyx mori).

Xanthine dehydrogenase (XDH) is a molybdoenzyme which catalyses oxidation of xanthine and hypoxanthine to uric acid. We isolated genomic clones of silkworm (Bombyx mori) XDH genes (BmXDH1 and BmXDH2). The BmXDH2 gene is located upstream from the BmXDH1 gene and they show a tandemly duplicated structure. Both BmXDH genes were expressed in the fat body and Malpighian tubules, whereas only the BmXDH1 gene was expressed in the midgut. Phylogenetic analysis indicates that BmXDH gene duplication occurred after the divergence of the silkworm and dipteran species. Intron insertion site comparison shows that some introns were lost during insect XDH gene evolution.

Amino Acid Sequence↗
PubMed1997

Effect of glucocorticoids on the synthesis of antimicrobial peptides in amphibian skin.

Gene-encoded peptide antibiotics are widespread in insects, plants and vertebrates and confer protection against bacterial and fungal infections. NF-kappaB is an important transcription factor for many immunity-related mammalian proteins and also for insect immune genes. The activity of NF-kappaB is regulated by the interaction with an inhibitor, I kappaB. It was recently demonstrated that glucocorticoids induce the synthesis of I kappaB in human cell lines. So far, all genes for peptide antibiotics have promoter motifs with NF-kappaB binding sites, but its actual function in peptide regulation has been studied only in insects. Here we show that glucocorticoid treatment of the frog Rana esculenta inhibits the transcription of all genes encoding antibacterial peptides by inducing the synthesis of I kappaB alpha. These results suggest that also in vertebrates peptide-mediated innate immunity is controlled by NF-kappaB-regulated transcription.

Amphibian Proteins↗
PubMed1991

Structure and expression of the attacin genes in Hyalophora cecropia.

To study the regulation of the immune genes in insects, we have cloned and sequenced the attacin gene locus of the giant silk moth Hyalophora cecropia. The locus contains one acidic and one basic attacin gene as well as two pseudogenes, which are remnants of basic attacin genes. A small insertion element was found within the locus. The two functional attacin genes are transcribed in opposite directions and have two introns inserted at homologous positions. A common sequence, GGGGATTCCT, is found at nucleotide position -48 in the acidic gene and at nucleotide position -58 in the basic gene. Interestingly, this decanucleotide is similar to the consensus of the NF-k B-binding site. Expression studies revealed that both attacins are strongly induced by phorbol 12-myristate 13-acetate, lipopolysaccharide and bacteria. However, only the acidic attacin gene showed a clear response to injury.

Animals↗
PubMed2002

Two different genes encoding acetylcholinesterase existing in cotton aphid (Aphis gossypii).

Two acetylcholinesterase (AChE) genes, Ace1 and Ace2, have been cloned from cotton aphid, Aphis gossypii Glover, using the rapid amplification of cDNA ends (RACE) technique. To the best of our knowledge, this should be the first direct molecular evidence that multiple AChE genes exist in insects. The Ace1 gene was successfully amplified along its full length of 2371 bp. The open reading frame is 2031 bp long and encodes 676 amino acids (GenBank accession No. AF502082). The Ace2 gene was amplified as a mega-fragment of 2130 bp lacking part of 5'-end untranslated region (UTR). The open reading frame is 1992 bp long and ecodes a protein of 664 amino acids (GenBank accession No. AF502081). Both genes have the conserved amino acids and features shared by the AChE family, but share only 35% identity in amino acid sequence. The Ace1 gene is highly homologous to the AChE gene of Schizaphis graminum (AF321574) with 95% identity, and Ace2 to that of Myzus persicae (AF287291) with 92% identity. Phylogenetic analysis showed that the two cloned AChEs of A. gossypii are different in evolution. The phylogenetic tree generated by the PHYLIP program package inferred that AChE2 of A. gossypii is a more ancestral form of AChE. Homology modeling of structures using Torpedo californica (2ACE_) and Drosophila melanogaster (1Q09:A) native acetylcholinesterase structure as main template indicated that the two AChEs of Aphis gossypii might have different three-dimensional structures. Alternative splicing of Ace1 near the 5'-end resulting in two proteins differing by the presence or absence of a fragment of four amino acids is also reported.

Acetylcholinesterase↗
PubMed2006

Carbohydrate metabolism genes and pathways in insects: insights from the honey bee genome.

Carbohydrate-metabolizing enzymes may have particularly interesting roles in the honey bee, Apis mellifera, because this social insect has an extremely carbohydrate-rich diet, and nutrition plays important roles in caste determination and socially mediated behavioural plasticity. We annotated a total of 174 genes encoding carbohydrate-metabolizing enzymes and 28 genes encoding lipid-metabolizing enzymes, based on orthology to their counterparts in the fly, Drosophila melanogaster, and the mosquito, Anopheles gambiae. We found that the number of genes for carbohydrate metabolism appears to be more evolutionarily labile than for lipid metabolism. In particular, we identified striking changes in gene number or genomic organization for genes encoding glycolytic enzymes, cellulase, glucose oxidase and glucose dehydrogenases, glucose-methanol-choline (GMC) oxidoreductases, fucosyltransferases, and lysozymes.

Animals↗
PubMed2000

Gene flow and selection balance in haplodiploid social insects.

Understanding the joint effects of gene flow and selection is one of the more important but difficult areas of evolutionary genetics. A method is presented to describe cases of gene flow-selection balance while accounting for the life history of haplodiploid social insects (eusocial Hymenoptera). A continent-island model is used to estimate gene flow rates from allele frequency data and provide variance formulae. The occurrence of unequal yet stable allele frequencies among social insect castes is explained and the usefulness of models with discrete generations for eusocial insects is explained. Gene flow and selection balance has been demonstrated for the fire ant Solenopsis invicta at two allozyme loci. This continent-island model gives results that well describe the system. Issues fundamental to the differences between X-linked and haplodiploid genetic systems and diploid genetic systems are also discussed.

Animals↗
PubMed1992

A sensitive model system for in vivo monitoring of baculovirus gene expression in single infected insect cells.

We have developed a fast and sensitive system for the in vivo analysis of gene expression in baculovirus infected lepidopteran insect cells. A recombinant baculovirus containing a luciferase gene from the click beetle, Pyrophorus plagiophthalamus, under transcriptional regulation of the polyhedrin gene promoter of Autographa californica nuclear polyhedrosis virus (AcNPV) was used to infect a Spodoptera frugiperda cell line. Recombinant luciferase could be monitored by luminometry in real-time without disruption of the infected cells, allowing detection of synthesis as early as one hour after infection. The range of luminescence measurements was normally over four orders of magnitude, and the kinetics of luciferase synthesis and the levels of light produced in vivo closely correlated with the expression of polyhedrin in AcNPV infected cells when analyzed by SDS-PAGE. Additionally, single infected cells could be identified by CCD image analysis and flow cytometry.

Animals↗
PubMed2000

Human homologue of the Drosophila discs large tumor suppressor protein forms an oligomer in solution. Identification of the self-association site.

The human homologue of the Drosophila discs large tumor suppressor protein (hDlg), a member of the membrane-associated guanylate kinase (MAGUK) superfamily, interacts with K(+) channels, N-methyl-d-aspartate receptors, calcium ATPase, adenomatous polyposis coli, and PTEN tumor suppressor proteins, and several viral oncoproteins through its PDZ domains. MAGUKs play pivotal roles in the clustering and aggregation of receptors, ion channels, and cell adhesion molecules at the synapses. To investigate the physiological basis of hDlg interactions, we examined the self-association state of full-length hDlg as well as defined segments of hDlg expressed as recombinant proteins in bacteria and insect Sf9 cells. Gel permeation chromatography of full-length hDlg revealed that the purified protein migrates as a large particle of size >440 kDa. Similar measurements of defined domains of hDlg indicated that the anomalous mobility of hDlg originated from its amino-terminal domain. Ultrastructural analysis of hDlg by low angle rotary shadow electron microscopy revealed that the full-length hDlg protein as well as its amino-terminal domain exhibits a highly flexible irregular shape. Further evaluation of the self-association state of hDlg using sedimentation equilibrium centrifugation, matrix-assisted laser desorption/ionization mass spectrometry, and chemical cross-linking techniques confirmed that the oligomerization site of hDlg is contained within its amino-terminal domain. This unique amino-terminal domain mediates multimerization of hDlg into dimeric and tetrameric species in solution. Sedimentation velocity experiments demonstrated that the oligomerization domain exists as an elongated tetramer in solution. In vitro mutagenesis was used to demonstrate that a single cysteine residue present in the oligomerization domain of hDlg is not required for its self-association. Understanding the oligomerization status of hDlg may help to explicate the mechanism of hDlg association with multimeric K(+) channels and dimeric adenomatous polyposis coli tumor suppressor protein. Our findings, therefore, begin to rationalize the role of hDlg in the clustering of membrane channels and formation of multiprotein complexes necessary for signaling and cell proliferation pathways.

Animals↗
PubMed1998

Absence of dosage compensation at the transcription level of a sex-linked gene in a female heterogametic insect, Bombyx mori.

To confirm whether sex-linked genes of the silkworm are dosage compensated or not, we investigated three RAPDs and one RFLP marker which have been mapped to the Z chromosome as candidate genes to test for dosage compensation. Northern blot analysis demonstrated that one of the RAPDs, T15.180a, is transcribed into several mRNAs in the embryo, midgut, Malpighian tubule, testis and ovary. Southern blot analysis revealed that T15.180a is present at one copy in the genome. Sequence data showed that T15.180a contained two open-reading frames (ORFs) separated by an intron of 605 bp. These ORFs encoded a possible polypeptide of 445 amino acids containing the proline cluster. These results suggested that T15.180a is part of a functional gene on the Z chromosome of the silkworm. We have called this gene T15, and compared its transcriptional level between males and females. Northern blot analysis showed that the level of T15 mRNA in males was twice that of females. For a more precise analysis, the levels of transcription from both alleles of T15 (T15P, T15C) were measured by the single-nucleotide primer extension (SNuPE) assay. The results indicated that the amount of transcription from each T15 allele in both sexes (male, T15P/T15C; female, T15P/W) was equivalent. All the results suggest that sex-linked genes in the silkworm are not dosage compensated.

Alleles↗
PubMed1997

Relationships between protein isoforms and genetic functions demonstrate functional redundancy at the Broad-Complex during Drosophila metamorphosis.

Metamorphosis in holometabolous insects is an ecdysone-dependent process by which the larval form is replaced by a reproductive, adult form. At the onset of metamorphosis ecdysone induces a set of early genes which coordinate tissue-specific responses to hormone. The Broad-Complex (BR-C) early gene, which acts as a global regulator of tissue-specific responses to ecdysone, encodes a family of zinc-finger DNA binding proteins known as Z1, Z2, Z3, and Z4. Genetically the BR-C encodes three complementing functions, br, rbp, and 2Bc, and a class of npr1 alleles that fail to complement any of the other genetic functions. The effects of BR-C mutations on metamorphic development are highly pleiotropic, yet little is known about the roles of individual BR-C proteins in directing the required responses to ecdysone. Because the BR-C is a vital regulator of metamorphosis it is essential to establish the relationships between BR-C genetic functions and protein products. We present here the first general and definitive study of these relationships. Using heat-inducible transgenes we have rescued lethality associated with each of the complementing genetic functions and have restored transcriptional activity of tissue-specific BR-C(+)-dependent target genes. Our data lead us to conclude that br+ function is only provided by the Z2 isoform. We find that Z1 transgenes provide full rbp+ function, while Z4 provides partial function. Likewise, while Z3 provides full 2Bc+ function, Z2 also provides partial function. These results indicate possible functional redundancy or regulatory dependence (via autoregulation) associated with the rbp+ and 2Bc+ functions. The establishment of these relationships between BR-C genetic functions and protein isoforms is an important step toward understanding the roles of BR-C proteins in directing metamorphic responses to ecdysone.

Alcohol Dehydrogenase↗
PubMed1998

Pair-rule and gap gene mutants in the flour beetle Tribolium castaneum.

Early pattern formation in the Drosophila embryo occurs in a syncytial blastoderm where communication between nuclei is unimpeded by cell walls. During the development of other insects, similar gene expression patterns are generated in a cellular environment. In Tribolium, for instance, pair-rule stripes are transiently expressed near the posterior end of the growing germ band. To elucidate how pattern formation in such a situation deviates from that of Drosophila, functional data about the genes involved are essential. In a genetic screen for Tribolium mutants affecting the larval cuticle pattern, we isolated 4 mutants (from a total of 30) which disrupt segmentation in the thorax and abdomen. Two of these mutants display clear pair-rule phenotypes. This demonstrates that not only the expression, but also the function of pair-rule genes in this short-germ insect is in principle similar to Drosophila. The other two mutants appear to identify gap genes. They provide the first evidence for the involvement of gap genes in abdominal segmentation of short-germ embryos. However, significant differences between the phenotypes of these mutants and those of known Drosophila gap mutants exist which indicates that evolutionary changes occurred in either the regulation or action of these genes.

Animals↗