The cuticular hydrocarbons of the Triatoma sordida species subcomplex (Hemiptera: Reduviidae)

The cuticular hydrocarbons of the Triatoma sordida subcomplex (Hemiptera: Reduviidae: Triatominae) were ana- lysed by gas chromatography and their structures identified by mass spectrometry. They comprised mostly n-alkanes and methyl-branched alkanes with one-four methyl substitutions. n-alkanes consisted of a homologous series from C21-C33 and represented 33-45% of the hydrocarbon fraction; n-C29 was the major component. Methyl-branched alkanes showed alkyl chains from C24-C43. High molecular weight dimethyl and trimethylalkanes (from C35-C39) represented most of the methyl-branched fraction. A few tetramethylalkanes were also detected, comprising mostly even-numbered chains. Several components such as odd-numbered 3-methylalkanes, dimethylalkanes and trimethylalkanes of C37 and C39 showed patterns of variation that allowed the differentiation of the species and populations studied. Triatoma guasayana and Triatoma patagonica showed the most distinct hydrocarbon patterns within the subcomplex. The T. sordida populations from Brazil and Argentina showed significantly different hydrocarbon profiles that posed concerns regarding the homogeneity of the species. Triatoma garciabesi had a more complex hydrocarbon pattern, but it shared some similarity with T. sordida. The quantitative and qualitative variations in the cuticular hydrocarbons may help to elucidate the relationships between species and populations of this insect group.Instituto de Investigaciones Bioquímicas de La Plat

Tracing the coevolution between <i>Triatoma infestans</i> and its fungal pathogen <i>Beauveria bassiana</i>

The chemical control of Triatoma infestans, the major Chagas disease vector in southern South America, has been threatened in the last years by the emergence of pyrethroid-resistant bug populations. As an alternative approach, the efficacy of the entomopathogenic fungus Beauveria bassiana to control T. infestans populations (regardless their pyrethroid susceptibility) has been demonstrated. Growing research efforts on the interaction between T. infestans and B. bassiana by molecular, ecological, biochemical and behavioral traits has allowed framing such interaction as an evolutionary arms race. This review will focus on the relationships established in this particular host-pathogen system, compiling available data on the relevance of fungal pathogenesis, insect behavior, population dynamics and human intervention to favor fungal dissemination in bug populations. The current snapshot shows the fungus ahead in the evolutionary arms race and predicts a promissory landscape for the biological control of Chagas disease vectors.Instituto de Investigaciones Bioquímicas de La PlataFacultad de Ciencias Exacta

Molecular characterization and expression analysis of a suite of cytochrome P450 enzymes implicated in insect hydrocarbon degradation in the entomopathogenic fungus Beauveria bassiana

The insect epicuticle or waxy layer comprises a heterogeneous mixture of lipids that include abundant levels of long-chain alkanes, alkenes, wax esters and fatty acids. This structure represents the first barrier against microbial attack and for broad-host-range insect pathogens, such as Beauveria bassiana, it is the initial interface mediating the host-pathogen interaction, since these organisms do not require any specialized mode of entry and infect target hosts via the cuticle. B. bassiana is able to grow on straight chain alkanes up to n-C33 as a sole source of carbon and energy. The cDNA and genomic sequences, including putative regulatory elements, for eight cytochrome P450 enzymes, postulated to be involved in alkane and insect epicuticle degradation, were isolated and characterized. Expression studies using a range of alkanes as well as an insect-derived epicuticular extract from the blood-sucking bug Triatomas infestans revealed a differential expression pattern for the P450 genes examined, and suggest that B. bassiana contains a series of hydrocarbon-assimilating enzymes with overlapping specificity in order to target the surface lipids of insect hosts. Phylogenetic analysis of the translated ORFs of the sequences revealed that the enzyme which displayed the highest levels of induction on both alkanes and the insect epicuticular extract represents the founding member of a new cytochrome P450 family, with three of the other sequences assigned as the first members of new P450 subfamilies. The remaining four proteins clustered with known P450 families whose members include alkane monooxygenases.Facultad de Ciencias Exacta

Molecular characterization and expression analysis of a suite of cytochrome P450 enzymes implicated in insect hydrocarbon degradation in the entomopathogenic fungus Beauveria bassiana

The insect epicuticle or waxy layer comprises a heterogeneous mixture of lipids that include abundant levels of long-chain alkanes, alkenes, wax esters and fatty acids. This structure represents the first barrier against microbial attack and for broad-host-range insect pathogens, such as Beauveria bassiana, it is the initial interface mediating the host-pathogen interaction, since these organisms do not require any specialized mode of entry and infect target hosts via the cuticle. B. bassiana is able to grow on straight chain alkanes up to n-C33 as a sole source of carbon and energy. The cDNA and genomic sequences, including putative regulatory elements, for eight cytochrome P450 enzymes, postulated to be involved in alkane and insect epicuticle degradation, were isolated and characterized. Expression studies using a range of alkanes as well as an insect-derived epicuticular extract from the blood-sucking bug Triatomas infestans revealed a differential expression pattern for the P450 genes examined, and suggest that B. bassiana contains a series of hydrocarbon-assimilating enzymes with overlapping specificity in order to target the surface lipids of insect hosts. Phylogenetic analysis of the translated ORFs of the sequences revealed that the enzyme which displayed the highest levels of induction on both alkanes and the insect epicuticular extract represents the founding member of a new cytochrome P450 family, with three of the other sequences assigned as the first members of new P450 subfamilies. The remaining four proteins clustered with known P450 families whose members include alkane monooxygenases.Facultad de Ciencias Exacta

Mejoramiento de micoinsecticidas: un enfoque desde la interacción entre la cutícula de insectos y los hongos entomopatógenos

Los insecticidas de contacto, sean químicos, físicos o biológicos, encuentran en la cutícula del insecto hospedador la primera barrera a la penetración. La misma está formada por varias capas, de afuera hacia adentro: la epicutícula, la procutícula y la epidermis. La epicutícula es muy fina (0,1-3 μm) y está constituida por varias laminas, cada una de las cuales posee diferente estructura y propiedades químicas (Juárez &amp; Calderón Fernández 2007). Si bien los componentes mayoritarios de la cutícula son proteínas y quitina (constituida por cadenas organizadas de N-glucosamina), la superficie más externa de la epicutícula está compuesta de una mezcla compleja de lípidos no polares. Predominan hidrocarburos alifáticos (HC) lineales y ramificados de muy largas cadenas (entre 20 y 40 átomos de carbono), alcoholes grasos, ceras, glicéridos y ácidos grasos libres de variadas estructuras (Blomquist et al. 1987). Su principal función es restringir la pérdida de agua, controlar la absorción de sustancias químicas, la actividad de microorganismos y actuar en procesos de comunicación química inter o intra especies (Juárez 1994; Blomquist 2003). Dada la carencia de grupos reactivos y la alta estabilidad de los HC de insecto, se les atribuye un rol fundamental dentro de las propiedades de barrera de la cutícula antes mencionadas.Trabajo publicado en Berón, C., Plischuk, S. y Consolo, F. (eds.). I Taller Argentino de Patología de Insectos y sus Aplicaciones en Biocontrol. Mar del Plata: Universidad Nacional de Mar del Plata, 2013.Facultad de Ciencias Médica

Mejoramiento de micoinsecticidas: un enfoque desde la interacción entre la cutícula de insectos y los hongos entomopatógenos

Los insecticidas de contacto, sean químicos, físicos o biológicos, encuentran en la cutícula del insecto hospedador la primera barrera a la penetración. La misma está formada por varias capas, de afuera hacia adentro: la epicutícula, la procutícula y la epidermis. La epicutícula es muy fina (0,1-3 μm) y está constituida por varias laminas, cada una de las cuales posee diferente estructura y propiedades químicas (Juárez &amp; Calderón Fernández 2007). Si bien los componentes mayoritarios de la cutícula son proteínas y quitina (constituida por cadenas organizadas de N-glucosamina), la superficie más externa de la epicutícula está compuesta de una mezcla compleja de lípidos no polares. Predominan hidrocarburos alifáticos (HC) lineales y ramificados de muy largas cadenas (entre 20 y 40 átomos de carbono), alcoholes grasos, ceras, glicéridos y ácidos grasos libres de variadas estructuras (Blomquist et al. 1987). Su principal función es restringir la pérdida de agua, controlar la absorción de sustancias químicas, la actividad de microorganismos y actuar en procesos de comunicación química inter o intra especies (Juárez 1994; Blomquist 2003). Dada la carencia de grupos reactivos y la alta estabilidad de los HC de insecto, se les atribuye un rol fundamental dentro de las propiedades de barrera de la cutícula antes mencionadas.Trabajo publicado en Berón, C., Plischuk, S. y Consolo, F. (eds.). I Taller Argentino de Patología de Insectos y sus Aplicaciones en Biocontrol. Mar del Plata: Universidad Nacional de Mar del Plata, 2013.Facultad de Ciencias Médica

Volatile organic compounds released by the entomopathogenic fungus Beauveria bassiana

The composition of volatile organic compounds (VOC) released by the entomopathogenic fungus Beauveria bassiana (Hyphomycete: Deuteromycotina) utilizing two different carbon sources was investigated. Analyses were performed by solid-phase microextraction (SPME) coupled to capillary gas chromatography (CGC) and CGC-mass spectrometry (MS). Major components in glucose-grown cultures were diisopropyl naphthalenes, ethanol, and sesquiterpenes. Alkane-grown fungal VOC switched to a fingerprint with prevalence of n-decane. This is the first report on the volatiles released by entomopathogenic fungi.Instituto de Investigaciones Bioquímicas de La PlataCentro de Investigaciones de Fitopatologí

Volatile organic compounds released by the entomopathogenic fungus Beauveria bassiana

The composition of volatile organic compounds (VOC) released by the entomopathogenic fungus Beauveria bassiana (Hyphomycete: Deuteromycotina) utilizing two different carbon sources was investigated. Analyses were performed by solid-phase microextraction (SPME) coupled to capillary gas chromatography (CGC) and CGC-mass spectrometry (MS). Major components in glucose-grown cultures were diisopropyl naphthalenes, ethanol, and sesquiterpenes. Alkane-grown fungal VOC switched to a fingerprint with prevalence of n-decane. This is the first report on the volatiles released by entomopathogenic fungi.Instituto de Investigaciones Bioquímicas de La PlataCentro de Investigaciones de Fitopatologí

Contribution of the horizontal transmission of the entomopathogenic fungus <i>Beauveria bassiana</i> to the overall performance of a fungal powder formulation against <i>Triatoma infestans</i>

The aim of study was to investigate the effect of hydroxylpropylmethylcellulose (HPMC), arabic gum (AG), konjac glucomannan (KG) and apple pectin (AP) at 2% (w/w, potato–wheat flour basis) on the potato–wheat dough (the mass ratio was 1:1) rheological, fermentation and bread making properties. The tan d of potato–wheat dough was significantly increased upon addition of adding HPMC which was close to wheat dough (0.531). Moreover, dough height during fermentation process was significantly improved on addition of hydrocolloids, with the order of HPMC (23.1 mm)[AP (19.3 mm)[AG (18.6 mm)[ KG (13.6 mm). Protein bands of potato–wheat dough were pale in the presence of hydrocolloids, suggesting the formation of higher molecular weight aggregates formed between proteins–hydrocolloids or proteins–proteins after fermentation process. Furthermore, HPMC significantly increased specific volume (from 1.45 to 2.22 ml/g), and hydrocolloids restricted the retrogradation of starch in potato–wheat breads.Instituto de Investigaciones Bioquímicas de La Plat

The cuticular hydrocarbons of the Triatoma sordida species subcomplex (Hemiptera: Reduviidae)

The cuticular hydrocarbons of the Triatoma sordida subcomplex (Hemiptera: Reduviidae: Triatominae) were ana- lysed by gas chromatography and their structures identified by mass spectrometry. They comprised mostly n-alkanes and methyl-branched alkanes with one-four methyl substitutions. n-alkanes consisted of a homologous series from C21-C33 and represented 33-45% of the hydrocarbon fraction; n-C29 was the major component. Methyl-branched alkanes showed alkyl chains from C24-C43. High molecular weight dimethyl and trimethylalkanes (from C35-C39) represented most of the methyl-branched fraction. A few tetramethylalkanes were also detected, comprising mostly even-numbered chains. Several components such as odd-numbered 3-methylalkanes, dimethylalkanes and trimethylalkanes of C37 and C39 showed patterns of variation that allowed the differentiation of the species and populations studied. Triatoma guasayana and Triatoma patagonica showed the most distinct hydrocarbon patterns within the subcomplex. The T. sordida populations from Brazil and Argentina showed significantly different hydrocarbon profiles that posed concerns regarding the homogeneity of the species. Triatoma garciabesi had a more complex hydrocarbon pattern, but it shared some similarity with T. sordida. The quantitative and qualitative variations in the cuticular hydrocarbons may help to elucidate the relationships between species and populations of this insect group.Instituto de Investigaciones Bioquímicas de La Plat