RESUMEN
Aphidius ervi is an endophagous braconid, parasitoid of the pea aphid, Acyrthosiphon pisum. A. ervi teratocytes, deriving from the dissociation of the embryonic serosa, synthesize and release two major proteins into the host haemocoel. The gene of one of these proteins has been cloned and characterized. This gene codes for a 15.8 kDa protein belonging to the fatty acid binding protein (FABP) family, named Ae-FABP (A. ervi-FABP). It is abundantly present in the host haemolymph when the parasitoid larva attains its maximum growth rate. The recombinant Ae-FABP binds to fatty acids in vitro, showing a high affinity to C14-C18 saturated fatty acids and to oleic and arachidonic acid. The possible nutritional role for the parasitoid larva of Ae-FABP is discussed.
Asunto(s)
Áfidos/parasitología , Proteínas Portadoras/genética , Avispas/citología , Avispas/metabolismo , Secuencia de Aminoácidos , Naftalenosulfonatos de Anilina/metabolismo , Animales , Secuencia de Bases , Northern Blotting , Southern Blotting , Proteínas Portadoras/metabolismo , Clonación Molecular , Cartilla de ADN , Proteínas de Unión a Ácidos Grasos , Interacciones Huésped-Parásitos , Datos de Secuencia Molecular , Alineación de Secuencia , Análisis de Secuencia de ADN , Avispas/genéticaRESUMEN
Toxoneuron nigriceps (Viereck) (Hymenoptera, Braconidae) is an endophagous parasitoid of the tobacco budworm Heliothis virescens (F.) (Lepidoptera, Noctuidae). Parasitized H. virescens larvae are developmentally arrested and show a complex array of pathological symptoms ranging from the suppression of the immune response to an alteration of ecdysone biosynthesis and metabolism. Most of these pathological syndromes are induced by the polydnavirus associated with T. nigriceps (TnBV). An overview of our recent research work on this system is described herein. The mechanisms involved in the disruption of the host hormonal balance have been further investigated, allowing to better define the physiological model previously proposed. A functional genomic approach has been undertaken to identify TnBV genes expressed in the host and to assess their role in the major parasitoid-induced pathologies. Some TnBV genes cloned so far are novel and do not show any similarity with genes already available in genomic databases, while others code for proteins having conserved domains, such as aspartic proteases and tyrosine phosphatases. Sequencing of the entire TnBV genome is in progress and will considerably contribute to the understanding of the molecular bases of parasitoid-induced host alterations.
Asunto(s)
Himenópteros/fisiología , Lepidópteros/fisiología , Lepidópteros/parasitología , Secuencia de Aminoácidos , Animales , Ácido Aspártico Endopeptidasas/biosíntesis , Ácido Aspártico Endopeptidasas/genética , Glándulas Endocrinas/fisiología , Expresión Génica , Genes Virales , Genoma Viral , Interacciones Huésped-Parásitos , Himenópteros/genética , Himenópteros/virología , Larva/crecimiento & desarrollo , Larva/metabolismo , Lepidópteros/genética , Datos de Secuencia Molecular , Polydnaviridae/enzimología , Polydnaviridae/genética , Proteínas Estructurales Virales/genéticaRESUMEN
Cardiochiles nigriceps Viereck is an endophagous parasitoid of larval stages of the tobacco budworm, Heliothis virescens (F.). This hymenopteran parasitoid, belonging to the family Braconidae, is associated with a polydnavirus (CnPDV), injected at ovi-position along with the egg. The infection of various tissues by CnPDV determines the suppression of the host immune system and the developmental arrest of mature host larvae. In this study, CnPDV has been characterized at the structural and molecular level. The negatively stained nucleocapsids show evident 'end structures' and a tail-like appendage. The CnPDV genome is typically segmented, with circular dsDNA molecules, ranging in size from 2.5 kb to more than 23 kb. The early expression pattern of CnPDV in parasitized hosts has been analysed and viral clones, genomic and cDNAs, identifying genes expressed within 48 h after parasitization have been isolated. The molecular organization of one of these genes, named CnPDV1, and its putative protein product have been determined. Significant sequence homologies with other known proteins were not detected. In situ hybridization experiments indicated that this gene is expressed in the prothoracic glands of parasitized host mature larvae. A functional analysis of CnPDV1 gene product is required to assess its possible role in the regulation of parasitoid-induced alterations of host larvae.
Asunto(s)
Mariposas Nocturnas/parasitología , Polydnaviridae/genética , Proteínas Virales/genética , Avispas/virología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , ADN Complementario , Expresión Génica , Genes Virales , Genoma Viral , Larva/parasitología , Datos de Secuencia MolecularRESUMEN
We performed a molecular analysis of the Aphidius ervi ribosomal gene structure. This insect belongs to a set of closely related Aphidiinae species of the genus Aphidius Nees, of relevant interest in biological control. We constructed A. ervi genomic libraries, cloned and characterized several rDNA repeating units and sequenced different regions of the rDNA cistrons. We have found that insertion sequences interrupt the A. ervi 28S rDNA genes: the sequences of the two 5' and 3' insertion-28S junctions show that the elements are present at the position where R1 elements have been found in various insect species. In addition, the insertion of the element produces a duplication of the 14 nt target region. The sequence analysis indicates that the A. ervi elements belong to the R1 retrotransposon family with a highly conserved reverse transcriptase domain.
Asunto(s)
ADN Ribosómico , Genes de Insecto , Retroelementos , Ribosomas/genética , Avispas/genética , Secuencia de Aminoácidos , Animales , Bacteriófago lambda , Secuencia de Bases , Southern Blotting , Heterogeneidad Genética , Datos de Secuencia Molecular , ARN Ribosómico 28S/genética , Recombinación Genética , Secuencias Repetitivas de Ácidos NucleicosRESUMEN
Epidemiological and clinical evidence have indicated that apolipoprotein A1 and B determination can better define the lipoprotein pattern in normal subjects and in subjects with coronary heart disease. In this paper, a recent immunoturbidimetric method for routine apolipoprotein A1 and B measurement (using the Turbitimer system and commercially available antisera) has been evaluated. The precision and the accuracy of the method have been previously considered. Within-run and between-run coefficients of variation (ranging from 1.67% to 5.04%) for both assays indicate good precision of the method. Accuracy was evaluated on 2 consecutive days (n = 10 each run) using a standard serum for apolipoprotein A1 and B. The bias obtained was 3.79% for apolipoprotein A1 and 2.30% for B. Apolipoproteins A1 and B were then measured in 100 normal and hyperlipemic sera with the immunoturbidimetric assay and radial immunodiffusion (using the monoclonal antibodies). The data obtained were evaluated by linear regression analysis (Al, r = 0.893; B, r = 0.862). The good correlation between the two methods suggests that the immunoturbidimetric assay can be usefully performed for routine apolipoprotein A1 and B determination because of its lower cost, rapidity, and simplicity.