RESUMO
The pea aphid genome includes 66 genes contributing to amino acid biosynthesis and 93 genes to amino acid degradation. In several respects, the pea aphid gene inventory complements that of its symbiotic bacterium, Buchnera aphidicola (Buchnera APS). Unlike other insects with completely sequenced genomes, the pea aphid lacks the capacity to synthesize arginine, which is produced by Buchnera APS. However, consistent with other insects, it has genes coding for individual reactions in essential amino acid biosynthesis, including threonine dehydratase and branched-chain amino acid aminotransferase, which are not coded in the Buchnera APS genome. Overall the genome data suggest that the biosynthesis of certain essential amino acids is shared between the pea aphid and Buchnera APS, providing the opportunity for precise aphid control over Buchnera metabolism.
Assuntos
Aminoácidos/metabolismo , Afídeos/genética , Afídeos/metabolismo , Buchnera/genética , Buchnera/metabolismo , Genoma Bacteriano , Genoma de Inseto , Aminoácidos/biossíntese , Animais , Afídeos/microbiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Teste de Complementação Genética , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Modelos Biológicos , Pisum sativum/parasitologia , Simbiose/genética , Simbiose/fisiologia , Transaminases/genética , Transaminases/metabolismoRESUMO
We have investigated the development of the schistosome egg and its secretions in order to understand how it migrates through gut tissues and also initiates pathology in the liver. We show by electron microscopy that the subshell envelope is absent in the newly deposited egg, but appears very early and differentiates as development progresses. In the mature egg, this nucleated envelope contains extensive endoplasmic reticulum, suggestive of a protein synthetic capacity. Furthermore, Reynolds' layer only appears between the envelope and the egg-shell in the mature egg and may represent its accumulated secretions. We have biosynthetically labelled and collected the secretions (ESP) released by mature but not immature eggs during culture. Their fractionation by SDS-PAGE reveals a simple pattern of 6 bands, differing markedly in composition from soluble egg antigen preparations. Electrophoresis in casein substrate gels demonstrates the presence of 2 distinct proteases in the egg secretions. By immunocytochemistry, ESP localized predominantly to the envelope of the mature egg, suggesting that this layer rather than the miracidium is the source of egg secretions.
Assuntos
Óvulo/crescimento & desenvolvimento , Schistosoma mansoni/fisiologia , Animais , Técnicas de Cultura , Proteínas do Ovo/análise , Proteínas do Ovo/metabolismo , Eletroforese em Gel de Poliacrilamida/veterinária , Interações Hospedeiro-Parasita , Imuno-Histoquímica/veterinária , Fígado/parasitologia , Fígado/ultraestrutura , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Microscopia Eletrônica , Óvulo/metabolismo , CoelhosRESUMO
Parasite genome projects are generating an avalanche of sequence data. If this resource is to be exploited effectively for drug and vaccine design, there is an urgent need to make the link between these DNA sequences and the functional proteins of the parasite, which they encode. Here, we seek to demystify the revolutionary advances in protein identification based on mass spectrometry.