RESUMO
Plants are able to sense their environment and respond appropriately to different stimuli. Vibrational signals (VS) are one of the most widespread yet understudied ways of communication between organisms. Recent research into the perception of VS by plants showed that they are ecologically meaningful signals involved in different interactions of plants with biotic and abiotic agents. We studied changes in the concentration of alkaloids in tobacco plants induced by VS produced by Phthorimaea operculella (Lepidoptera: Gelechiidae), a generalist caterpillar that naturally feeds on the plant. We measured the concentration of nicotine, nornicotine, anabasine and anatabine in four treatments applied to 11-weeks old tobacco plant: a) Co = undamaged plants, b) Eq = Playback equipment attached to the plant without VS, c) Ca = Plants attacked by P. operculella herbivory and d) Pl = playback of VS of P. operculella feeding on tobacco. We found that nicotine, the most abundant alkaloid, increased more than 2.6 times in the Ca and Pl treatments as compared with the Co and Eq treatments, which were similar between them. Nornicotine, anabasine and anatabine were mutually correlated and showed similar concentration patterns, being higher in the Eq treatment. Results are discussed in terms of the adaptive significance of plant responses to ecologically important VS stimuli.
Assuntos
Alcaloides/análise , Lepidópteros/fisiologia , Nicotiana/química , Alcaloides/metabolismo , Anabasina/análise , Animais , Cromatografia Gasosa-Espectrometria de Massas , Herbivoria , Interações Hospedeiro-Parasita , Larva/fisiologia , Modelos Lineares , Nicotina/análogos & derivados , Nicotina/análise , Análise de Componente Principal , Piridinas/análise , Nicotiana/metabolismo , Nicotiana/parasitologia , VibraçãoRESUMO
A case of an actinomycotic brain abscess in an adult patient apparently free of systemic infection is presented. The rarity of this etiology of brain abscess is underlined. The patient was treated by complete surgical excision and prolonged antibiotic therapy with penicillin. The authors stress the importance of taking into account this infrequent cause of brain abscess, the necessity of radical surgical treatment followed by intensive, prolonged and adequate antibiotic therapy, as the only means of reducing the high mortality rate.