RESUMO
Complete mitochondrial genome sequences are presented from two dipluran hexapods (i.e., a group of "primarily wingless insects") of the genus Campodea and compared to those of other arthropods. Their gene order is the same as in most other hexapods and crustaceans. Structural changes have occurred in tRNA-C, tRNA-R, tRNA-S1 and tRNA-S2 as well as in both ribosomal RNAs. These mtDNAs have striking biases in nucleotide and amino acid composition. Although the two Campodea species are morphologically highly similar, their genetic divergence is larger than expected, suggesting a long evolutionary history, perhaps under stable ecological conditions.
Assuntos
DNA Mitocondrial , Deriva Genética , Genoma de Inseto , Insetos/genética , Animais , Composição de Bases , Sequência de Bases , Evolução Molecular , Mitocôndrias/genética , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Filogenia , Reação em Cadeia da Polimerase , RNA de Transferência/genéticaRESUMO
The complete mitochondrial genome of the bristletail Petrobius brevistylis has been determined. The genome is 15,698 bp long and bears the standard set of genes common to all arthropods as well as a major non-coding A+T-rich region, the putative mitochondrial control region. A unique gene order was revealed as it differs from other hexapod and crustacean mitochondrial genomes in the position of tRNA-Tyr. Genome features like nucleotide composition and codon usage are compared with that of other insect taxa. A+T content is similar in species of Archaeognatha and Zygentoma, but obviously lower than in Collembola and Pterygota. This A+T bias significantly affects also amino acid frequencies and may be a problem for phylogenetic analyses.
Assuntos
DNA Mitocondrial/química , Genes de Insetos , Genes Mitocondriais , Insetos/genética , Animais , Sequência de Bases , Códon , Ordem dos Genes , Genes de RNAr , Genoma de Inseto , Dados de Sequência Molecular , RNA de Transferência Aminoácido-Específico/química , Análise de Sequência de DNARESUMO
In this study we have analyzed bacterial lipopolysaccharide (LPS) induced genes in hemocytes of the Lepidopteran species Galleria mellonella using subtractive hybridization, followed by suppressive PCR. We have found genes that show homologies to molecules, such as gloverin, peptidoglycan recognition proteins and transferrin known to be involved in immunomodulation after bacterial infection in other species. In addition, a few molecules previously not described in the innate immune reactions were detected, such as a RNA binding molecule and tyrosine hydroxylase. Furthermore, the full-length cDNA of a LPS-induced molecule with six toxin-2-like domains is described to be a promising candidate to further elucidate the relationship between toxin- and defensin-like domains in arthropod host defense.
Assuntos
Genes de Insetos , Mariposas/imunologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Imunidade Inata , Proteínas de Insetos/química , Proteínas de Insetos/genética , Lipopolissacarídeos/farmacologia , Dados de Sequência Molecular , Mariposas/genética , Hibridização de Ácido Nucleico , Reação em Cadeia da PolimeraseRESUMO
A membrane associated ATP-dependent efflux pump, similar in function to mammalian P-glycoprotein, was detected in anal papillae of Chironomus riparius larvae. Immunohistochemical analysis of larval tissues, using monoclonal antibodies against P-glycoprotein, was supplemented by functional in vivo and in vitro assays which confirmed the existence of a mechanism for transporting xenobiotic substances. The in vitro ATPase activity of homogenate fractions increased in the presence of typical P-glycoprotein substrates (vinblastine, actinomycin D or ivermectin). This increase was unaffected by inhibitors of other membrane ATPases (sodium azide, EGTA, ouabain), but sensitive to vanadate, cyclosporin A and verapamil which inhibit mammalian P-glycoprotein mediated ATP-consumption. Sublethal concentrations of specific P-glycoprotein-inhibitors such as verapamil or cyclosporin A synergistically enhanced the mortality of C. riparius towards ivermectin. Although cyclosporin A originates from entomopathogenic fungi, its mode of action in insects and its function during infection are not understood. Our results lend some credit to the hypothesis that this compound is possibly released to promote poisoning of the infected host by xenobiotics which are normally removed by a P-glycoprotein related pump. The putative role of insect P-glycoprotein homologues in the context of multiple resistance towards insecticides in discussed.