734 resultados para Insect sex attractants.
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Colbertinus
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Colbertinus
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Mazarinaeus
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Mazarinaeus
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Colbertinus
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Although alcohol problems and alcohol consumption are related, consumption does not fully account for differences in vulnerability to alcohol problems. Therefore, other factors should account for these differences. Based on previous research, it was hypothesized that risky drinking behaviours, illicit and prescription drug use, affect and sex differences would account for differences in vulnerability to alcohol problems while statistically controlling for overall alcohol consumption. Four models were developed that were intended to test the predictive ability of these factors, three of which tested the predictor sets separately and a fourth which tested them in a combined model. In addition, two distinct criterion variables were regressed on the predictors. One was a measure of the frequency that participants experienced negative consequences that they attributed to their drinking and the other was a measure of the extent to which participants perceived themselves to be problem drinkers. Each of the models was tested on four samples from different populations, including fIrst year university students, university students in their graduating year, a clinical sample of people in treatment for addiction, and a community sample of young adults randomly selected from the general population. Overall, support was found for each of the models and each of the predictors in accounting for differences in vulnerability to alcohol problems. In particular, the frequency with which people become intoxicated, frequency of illicit drug use and high levels of negative affect were strong and consistent predictors of vulnerability to alcohol problems across samples and criterion variables. With the exception of the clinical sample, the combined models predicted vulnerability to negative consequences better than vulnerability to problem drinker status. Among the clinical and community samples the combined model predicted problem drinker status better than in the student samples.
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Conidia of the insect pathogenic fungus, Metarhizium anisopliae play an important role in pathogenicity because they are the infective propagules that adhere to the surface of the insect, then germinate and give rise to hyphal penetration of the insect cuticle. Conidia are produced in the final stages of insect infection as the mycelia emerge from the insect cadaver. The genes associated with conidiation have not yet been studied in this fiingus. hi this study we used the PCR-based technique, suppression subtractive hybridization (SSH) to selectively amplify conidial-associated genes in M. anisopliae. We then identified the presence of these differentially expressed genes using the National Center for Biotechnology Information database. One of the transcripts encoded an extracellular subtilisin-like protease, Prl, which plays a fundamental role in cuticular protein degradation. Analysis of the patterns of gene expression of the transcripts using RT-PCR indicated that conidial-associated cDNAs are expressed during the development of the mature conidium. RT-PCR analysis was also performed to examine in vivo expression of Prl during infection of waxworm larvae {Galleria mellonelld). Results showed expression of Prl as mycelia emerge and produce conidia on the surface of the cadaver. It is well documented that Prl is produced during the initial stages of transcuticular penetration by M. anisopliae. We suggest that upregulation of Prl is part of the mechanism by which reverse (from inside to the outside of the host) transcuticular penetration of the insect cuticle allows subsequent conidiation on the cadaver.
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Gamma-aminobutyric acid (GAB A) is a ubiquitous non-protein amino acid synthesized via the decarboxylation of L-glutamate in a reaction catalyzed by the cytosolic enzyme L-glutamate decarboxylase (GAD). In animals it functions as an inhibitory neurotransmitter. In plants it accumulates rapidly in response to various stresses, but its function remains unclear. The hypothesis that GABA accumulation in leaf tissue may function as a plant resistance mechanism against phytophagous insect activity was investigated. GABA accumulation in response to mechanical stimulation, mechanical damage and insect activity was demonstrated. In wt tobacco (Nicotiana tabacum cv Samsun), mechanical stimulation or damage caused GABA to accumulate within 2 min from mean levels of 14 to 37 and 1~9 nmol g-l fresh weight (FW), respectively. In the transgenic tobacco strain CaMVGAD27c overexpressing Petunia GAD, the same treatments caused GABA to accumulate from 12 to 59 and 279 nmol g-l FW, respectively. In the transgenic tobacco strain CaMVGADilC 11 overexpressing Petunia GAD lacking an autoinhibitory domain, mechanical stimulation or damage caused GABA to accumulate from 180 to 309 and 630 nmol g-l FW, respectively. Ambulatory activity by tobacco budworm (TBW) larvae (Heliothis virescens) on leaves of CaMVGAD27c tobacco caused GABA to accumulate from 28 to 80 nmol g-l FW within 5 min. Ambulatory and leaf-rolling activity by oblique banded leaf roller (OBLR) larvae (Choristoneura rosaceana cv Harris) on wt soybean leaves (Glycine max cv Harovinton) caused GABA to accumulate from 60 to 1123 nmol g-l FW within 20 min. Increased GABA levels in leaf tissue were shown to affect phytophagous preference in TBW larvae presented with wt and transgenic tobacco leaves. When presented with leaves of Samsun wt and CaMVGAD27c plants, TBW larvae consumed more wt leaf tissue (640 ± 501 S.D. mm2 ) than transgenic leaf tissue (278 ± 338 S.D. mm2 ) nine times out of ten. When presented with leaves of Samsun wt and CaMVGAD~C11 plants, TBW larvae consumed more transgenic leaf tissue (1219 ± 1009 S.D. mm2 ) than wt leaf tissue (28 ± 31 S.D. mm2 ) ten times out of ten. These results indicate that: (1) ambulatory activity of insect larvae on leaves results in increased GABA levels, (2) transgenic tobacco leaves with increased capacity for GABA synthesis deter feeding, and (3) transgenic tobacco leaves with constitutively higher GABA levels stimulate feeding.
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The sugar beet cyst nematode, Heterodera schachtii, is a major agricultural pest. The disruption of the mating behaviour of this plant parasite in the field may provide a means of biological control, and a subsequent increase in crop yield. The H. schachtii female sex pheromone, which attracts homospecific males, was collected in an aqueous medium and isolated using high performance liquid chromatography. Characterization of the male-attractive material revealed that it was heat stable and water soluble. The aqueous medium conditioned by female H. schachtii was found to be biologically active and stimulated male behaviour in a concentration dependent manner. The activity of the crude pheromone was specific to males of H. schachtii and did not attract second stage juveniles. Results indicated that vanillic acid, a putative nematode pheromone, is not an active component of the H. schachtii sex pheromone. Male H. schachtii exhibited stylet thrusting, a poorly understood behaviour of the male, upon exposure to the female sex pheromone. This behaviour appeared to be associated with mate-finding and was used as a novel indicator of biological activity in bioassays. Serotonin, thought to be involved in the neural control of copulatory behaviour in nematodes, stimulated stylet thrusting. However, the relationship between stylet thrusting induced by the sex pheromone and stylet thrusting induced by serotonin is not clear. Extracellular electrical activity was recorded fi-om the anterior region of H. schachtii males during stylet thrusting, and appeared to be associated with this behaviour. The isolation of the female sex pheromone of H. schachtii may, ultimately, lead to the structural identification and synthesis of the active substance for use in a novel biological control strategy.
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The monoconjugates of phenolic acids (i.e. coumaric acid) with polyamines such as spermidine and spermine are strikingly similar to some toxins from spiders and predatory wasps. Many plants contain phenolic acid polyamine conjugates and there is some reliable information supporting their roles as plant defense chemicals. Eleven monoacylated compounds of diamines, triamines, tetraamines and oxa-polyamine amines were prepared in three to seven steps: 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 and 32. The synthesis proceeds through stepwise construction of the polyamine backbone (as in 62 and 72), followed by protection and deprotection steps of the amino functions. Desymmetrization of readily available and prepared symmetrical polyamines is a key step in the synthesis. The protecting groups employed were tert-butoxycarbonyl (BOC) and trifluoroacetyl (TFA) group which were removed under different conditions: acid and base respectively. Deprotection and refunctionalization of the polyamine reagent demonstrated the versatility of these systems for N-acylation.
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Strain improvement of the insect pathogenic fungus Metarhizium anisopUae is necessary to increase its virulence towards agricultural pests and thus improve its commercial efficacy. Nevertheless, the release of genetically modified conidia in crop fields may negatively affect the ecosystem. Controlling conidiation is a potential means of limiting the release of engineered strains since conidia are the infective propagules and the means of dispersal. The purpose of this study was to research the colony development of M. anisopUae to identify potential targets for genetic manipulation to control conidiation. Following Agrobacterium tumefaciem insertional mutagenesis, phenotypic mutants were characterized using Y-shaped adaptor dependent extension PCR. Four of 1 8 colony development recombinants had T-DNA flanking sequences with high homology to genes encoding known signaling pathway proteins that regulate pathogenesis and/or asexual development in filamentous fungi. Conidial density counts and insect bioassays suggested that a Serine/Threonine protein kinase COTl homolog is not essential for conidiation or virulence. Furthermore, a choline kinase homolog is important for conidiation, but not virulence. Finally, the regulator of G protein signaling CAG8 and a NADPH oxidase NoxA homolog are necessary for conidiation and virulence. These genes are candidates for further investigation into the regulatory pathways controlling conidiation to yield insight into promising gene targets for biocontrol strain improvement.