RESUMO
Following injection of bacteria into the hemocoel of the fall webworm, Hyphantria cunea, several inducible genes were identified and characterized using PCR-based differential display (DD-PCR) and subtractive cloning. Ten immune-related cDNA clones (Hdd1, Hdd2, Hdd3, Hdd11, Hdd13, Hdd15, Hdd17, Hdd23, Hs106, Hs302) were isolated and characterized. The deduced amino acid sequence of Hdd2 was shown to be a member of the copper, zinc superoxide dismutase (Cu-Zn SOD) family. The H. cunea Cu-Zn SOD is novel in that it is up-regulated following a bacterial challenge and has a putative signal peptide suggesting its secretion and involvement in the insect immune response. Hdd3 was found to encode a new member of the serpin (serine protease inhibitor) family. The putative lectin corresponding to Hdd15 is of a different kind in that it has two lectin C domains in a single molecule. These two lectin C domains show significant homology to the lectin C domain of Periplaneta lipopolysaccharide binding protein (LPS-BP). Three cloned genes, Hdd17, Hs106 and Hs302, encode a homologue to Bombyx mori Gram negative binding protein, a hemolin-like protein and a attacin-like protein, respectively. The deduced amino acid sequences from Hdd11 showed weak homology with a Locusta migratoria hemolymph protein. On the contrary, Hdd1, Hdd13 and Hdd23 did not reveal any significant homology with known proteins. All of the 10 genes were clearly inducible by E. coli and M. luteus injection. Injection of distilled water only slightly induced mRNA levels. Comparison of temporal mRNA expression following E. coli injection showed three types of expression patterns.
Assuntos
DNA Complementar/isolamento & purificação , Escherichia coli/genética , Genes de Insetos , Mariposas/genética , Sequência de Aminoácidos , Animais , Clonagem Molecular , DNA Complementar/química , Lectinas/genética , Dados de Sequência Molecular , Mariposas/imunologia , Mariposas/microbiologia , Reação em Cadeia da Polimerase , RNA Mensageiro/análise , Alinhamento de Sequência , Serpinas/genética , Superóxido Dismutase/genéticaRESUMO
A cDNA clone for prophenoloxidase was isolated from the most important human malaria vector, Anopheles gambiae. The clone encoded a polypeptide of 79341 Da that contains the two copper binding domains common to all invertebrate prophenoloxidases and haemocyanins. Expression of the prophenoloxidase gene was detected throughout all life stages from egg to imago in two strains of A. gambiae; however, the strongest expression was observed in developing embryos in eggs. The prophenoloxidase gene was mapped to the inversion rich region of the right arm of chromosome-2 in region 13B.
Assuntos
Anopheles/enzimologia , Catecol Oxidase/genética , Mapeamento Cromossômico , Precursores Enzimáticos/genética , Genes de Insetos , Insetos Vetores/enzimologia , Sequência de Aminoácidos , Animais , Anopheles/genética , Sequência de Bases , Gatos , Clonagem Molecular , DNA Complementar , Expressão Gênica , Humanos , Proteínas de Insetos/genética , Insetos Vetores/genética , Malária/transmissão , Dados de Sequência Molecular , RNA Mensageiro , Coelhos , Homologia de Sequência de AminoácidosRESUMO
Two kinds of cDNA clones encoding prophenoloxidases (ProPO; zymogen of phenoloxidase (monophenol, L-dopa: oxygen oxydoreductase, EC 1.14.18.1)) were isolated by polymerase chain reaction (PCR) followed by screening of cDNA library that was prepared from whole larvae of the fall webworm, Hyphantria cunea (Lepidoptera, Arctiidae). The cDNAs encode 681 and 697 amino acids with molecular masses of 78.2 and 80.2 kDa, respectively. Deduced amino acid sequence homology between the two H. cunea ProPOs are only 49% whereas the homology against other insect ProPOs ranged from about 40 to 72%. The phylogenic analysis showed that the insect ProPOs are grouped mainly into two families. A putative proteolytic cleavage site for enzyme activation was identical to other insect ProPOs. The conserved copper binding sites were 84-62% homologous to arthropod ProPOs. Two additional highly conserved regions were found in the carboxy terminal. Furthermore, like other insect prophenoloxidases, hydrophobic signal peptide sequences were absent in the deduced ProPOs from H. cunea. Southern blot analysis indicated that the H. cunea ProPO1 is present as a single copy in the genome. Northern blot analysis showed that the expression of the ProPO genes were concentrated in mid-instar larvae, but were much lower in other developmental stages.