173 research outputs found
EFFECT OF TWO WHEAT CULTIVARS DIFFERING IN HYDROXAMIC ACID CONCENTRATION ON DETOXIFICATION METABOLISM IN THE APHID Sitobion avenae
Abstract—Hydroxamic acids (Hx) are wheat secondary metabolites conferring resistance for cereals against aphids. The activity of five enzymatic systems were evaluated in the aphid Sitobion avenae reared on the high-Hx wheat cultivar Chagual and the low-Hx wheat cultivar Huayún for 10 generations. Enzyme solutions were prepared from aphid homogenates and assayed for mixed function oxidases (including cytochrome P-450 monooxygenases and NADPH cytochrome c reductase), glutathione S-transferases, esterases, and catalase. Specific activities per aphid individual of cytochrome P-450 monooxygenases, NADPH cytochrome c reductase, glutathione S-transferases, and esterases were significantly increased in wheat cultivars relative to oat (only marginal increase of esterases in Chagual). Aphids fed on cv. Huayún showed an overall higher induction of enzymatic systems than those fed on cv. Chagual. Comparison of these results with reported effects of Hx on detoxifying enzymes in other insects, including aphids, support the hypothesis that these enzymatic pathways play an important role in the detoxification of toxic host-plant secondary metabolites. Key Words—Sitobion avenae, aphids, hydroxamic acids, DIMBOA, detoxification, cytochrome P-450 monooxygenases, NADPH cytochrome c reductase
Solitary Foraging in the Ancestral South American Ant, Pogonomyrmex vermiculatus. Is it Due to Constraints in the Production or Perception of Trail Pheromones?
Abstract Several North American species of Pogonomyrmex harvester ants exhibit group foraging, whereas South American species are exclusively solitary foragers. The composition of the secretions of the poison and Dufour glands in the South American species, Pogonomyrmex vermiculatus, were analyzed, and the secretions and their components were tested as trail pheromones in laboratory bioassays. The major compounds in the poison gland were the alkylpyrazines, 2,5-dimethylpyrazine, 2,3,5-trimethylpyrazine, and 3-ethyl-2,5-dimethylpyrazine. The Dufour gland contained five alkanes, from tridecane to heptadecane, with pentadecane being most abundant. In behavioral bioassays, poison gland extracts and the mixture of pyrazines produced a trail pheromone effect, whereas the Dufour gland extracts and the alkanes had no effect on ant locomotion. We conclude that group foraging in P. vermiculatus does not arise from the inability to produce or detect possible pheromones, but rather, from physiological and/or ecological factors
INHIBITION OF ENERGY METABOLISM BY BENZOXAZOLIN-2-ONE
Abstract--l. The effects of the title compound (BOA) on energy-linked reactions in mitochondria were studied. 2. BOA inhibited electron transfer between the flavin and ubiquinone in Complex I, and ATP synthesis at the F~ moiety of the ATPase complex. 3. These results are discussed in relation to the toxicity of BOA towards a wide range of aerobic organisms
Chemical self-recognition in the lizard Liolaemus fitzgeraldi
Abstract Social-chemical recognition is exhibited by all the Liolaemus lizards tested to date, except Liolaemus fitzgeraldi, which during post-hibernation did not discriminate chemosignals of same-sex individuals from a control. To clarify if L. fitzgeraldi is unique among the studied Liolaemus in lacking social-chemical recognition or if this was previously undetected, we recorded behavior during pre-and post-hibernation when confronted with chemosignals of conspecifics and from themselves. L fitzgeraldi showed self-recognition and seasonal changes in two exploratory behaviors. Potentially, conspecific recognition in L fitzgeraldi was undetected due to seasonality, but this species may rely comparatively less on chemical communication than congeners
PII: S0306-4565(00)00033-4
Abstract The effects of parasitisation by Aphidius ervi on the thermoregulatory behaviour of the pea aphid Acyrtosiphon pisum were studied in alfalfa fields and in an experimental thermal gradient. In the field, mummies were found exclusively on the adaxial surface of the upper leaves, and aphids in the mid canopy. The adaxial surface of the upper leaves was ca. 28C hotter that the mid-canopy. In the thermal gradient, the thermal effect (selected minus exposure temperature) was higher in magnitude in non-parasitised than in parasitised aphids; the thermal effects of both types of aphids were linearly and negatively correlated with exposure temperature (i.e. aphids showed negative thermal sensitivity). The thermal sensitivity of parasitised aphids was lower than that of non-parasitised aphids. The results are discussed in relation to hypotheses on factors governing the host-parasite relationship.
Actividad repelente del aceite esencial de Laurelia sempervirens (Ruiz & Pav.) Tul. (Monimiaceae) en Triatoma infestans (Klug) (Reduviidae)
Triatoma infestans (Klug) is the principal vector of Chagas disease in Bolivia and neighboring countries. The objective of this study was to determine the chemical composition of the EO of the Chilean laurel, Laurelia sempervirens (Ruiz & Pav.) Tul. (Monimiaceae) and to evaluate its repellent effect on fifth-instar nymphs of T. infestans. The EO from L. sempervirens was obtained by hydrodistillation and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Their main components were cis-isosafrole (89.8%), β-terpinene (3.9%), trans-ocimene (2.7%) and methyleugenol (2.2%). Repellency was evaluated on a circle of filter paper divided into two equal zones which were impregnated with test substances [EO or N,N-diethyl-3-methylbenzamide (DEET) as positive control] and acetone as blank control, respectively. Several concentrations of test substances between 4.125 and 132 ÎĽg/cm2 were tested. The EO from L. sempervirens produced significant repellency at concentrations equal or above 66.0 ÎĽg/cm2, while DEET repelled starting at 16.5 ÎĽg/cm2. Future works will be oriented to the study of repellent properties of cis-isosafrole alone and mixed with β-terpinene, trans-ocimene and methyleugenol on T. infestans.Triatoma infestans (Klug) es el vector principal de la enfermedad de Chagas en Bolivia y los paĂses vecinos. El objetivo de este estudio fue determinar la composiciĂłn quĂmica del AE del laurel chileno, Laurelia sempervirens (Ruiz & Pav.) Tul. (Monimiaceae) y evaluar su efecto repelente en ninfas del quinto estadio de T. infestans. La AE de L. sempervirens se obtuvo por hidrodestilaciĂłn y se analizĂł por cromatografĂa de gases acoplada a espectrometrĂa de masas (CG-EM). Sus componentes principales fueron cis-isosafrol (89.8%), βterpineno (3.9%), trans-ocimeno (2.7%) y metileugenol (2.2%). La repelencia se evaluĂł en un cĂrculo de papel de filtro dividido en dos zonas iguales que se impregnaron con sustancias de prueba [AE o N,N-dietil-3-metilbenzamida (DEET) como control positivo] y acetona como control en blanco, respectivamente. Se analizaron varias concentraciones de sustancias de prueba entre 4.125 y 132 ÎĽg/cm2. El AE de L. sempervirens produjo una repelencia significativa a concentraciones iguales o superiores a 66.0 ÎĽg/cm2, mientras que DEET repeliĂł a partir de 16.5 ÎĽg/cm2. Futuros trabajos serán orientados al estudio de las propiedades repelentes de cis-isosafrol solo y mezclado con βterpineno, trans-ocimeno y metileugenol en T. infestans.Fil: Mojica, Marycruz. Universidad Mayor Real y Pontificia de San Francisco Xavier de Chuquisaca; BoliviaFil: Alzogaray, RaĂşl Adolfo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Unidad de InvestigaciĂłn y Desarrollo EstratĂ©gico para la Defensa. Ministerio de Defensa. Unidad de InvestigaciĂłn y Desarrollo EstratĂ©gico para la Defensa; Argentina. Ministerio de Defensa. Instituto de Investigaciones CientĂficas y TĂ©cnicas para la Defensa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones CientĂficas y TĂ©cnicas para la Defensa. Centro de InvestigaciĂłn de Plagas e Insecticidas; ArgentinaFil: Mengoni, Sofia Laura. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Unidad de InvestigaciĂłn y Desarrollo EstratĂ©gico para la Defensa. Ministerio de Defensa. Unidad de InvestigaciĂłn y Desarrollo EstratĂ©gico para la Defensa; Argentina. Ministerio de Defensa. Instituto de Investigaciones CientĂficas y TĂ©cnicas para la Defensa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones CientĂficas y TĂ©cnicas para la Defensa. Centro de InvestigaciĂłn de Plagas e Insecticidas; ArgentinaFil: Reynoso, Mercedes MarĂa Noel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Unidad de InvestigaciĂłn y Desarrollo EstratĂ©gico para la Defensa. Ministerio de Defensa. Unidad de InvestigaciĂłn y Desarrollo EstratĂ©gico para la Defensa; Argentina. Ministerio de Defensa. Instituto de Investigaciones CientĂficas y TĂ©cnicas para la Defensa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones CientĂficas y TĂ©cnicas para la Defensa. Centro de InvestigaciĂłn de Plagas e Insecticidas; ArgentinaFil: Pinto, Carlos Fernando. Universidad Mayor Real y Pontificia de San Francisco Xavier de Chuquisaca; BoliviaFil: Niemeyer, Hermann M.. Universidad de Chile; ChileFil: EcheverrĂa, Javier. Universidad de Santiago de Chile; Chil
Inhibition of ATPase from chloroplasts by a hydroxamic acid from Gramineae.
Abstract-DIMBOA (2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one), a hydroxamic acid from the Gramineae involved in the resistance of cereals to aphids, inhibits energy transfer reactions. In this paper the effect of DIMBOA on the ATPase activity of chloroplast coupling factor 1 (CF,) was studied. A rapid inactivation of the enzyme was observed which increased with the concentration of DIMBOA. This inactivation was reversed by dilution and by filtration of the inhibitor. The inactivation was partially prevented by pre-treatment of the enzyme with iodoacetamide. A slower simultaneous inactivation was observed which followed pseudo-first order kinetics. It is suggested that part of the rapid inhibition of CF, ATPase caused by DIMBOA is due to its reaction with sulthydryl groups on the enzyme. These reactions of DIMBOA may explain some of the inhibitory properties of DIMBOA on a wide range of organisms
Insecticidal activity of the petroleum ether extract of ageratum conyzoides l.
Se estableciĂł que el extracto de Ă©ter de petrĂłleo (pe 40-60"') de Ageratum conyzoides L. presenta fuerte actividad insecticida contra larvas de tercer estadio de Musca domestica (DĂptera), contra larvas de tercer, cuarto y quinto estadio de Cynthia carye (Lepidoptera) y contra individuos adultos de Acanthoscelides obtectus (ColeĂłptera). En esta acciĂłn insecticida podrĂan estar involucrados dos flavonoides conocidos que se aislaron de este extracto: eupalestina y lucidina dimetilĂ©ter. TambiĂ©n se aislĂł prococeno II, cromeno Ă©ste que demostrĂł ser altamente tĂłxico contra larvas de M. domestica cuando las pruebas de contacto se hicieron irradiando con luz solar. En cambio, no mostrĂł ningĂşn efecto cuando los ensayos se hicieron en la oscuridad o bajo irradiaciĂłn de luz UV
Aptamers for pharmaceuticals and their application in environmental analytics
Aptamers are single-stranded DNA or RNA oligonucleotides, which are able to bind with high affinity and specificity to their target. This property is used for a multitude of applications, for instance as molecular recognition elements in biosensors and other assays. Biosensor application of aptamers offers the possibility for fast and easy detection of environmental relevant substances. Pharmaceutical residues, deriving from human or animal medical treatment, are found in surface, ground, and drinking water. At least the whole range of frequently administered drugs can be detected in noticeable concentrations. Biosensors and assays based on aptamers as specific recognition elements are very convenient for this application because aptamer development is possible for toxic targets. Commonly used biological receptors for biosensors like enzymes or antibodies are mostly unavailable for the detection of pharmaceuticals. This review describes the research activities of aptamer and sensor developments for pharmaceutical detection, with focus on environmental applications
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