Uncovering the multifaceted properties of 6-pentyl-alpha-pyrone for control of plant pathogens.

Some volatile organic compounds (VOCs) produced by microorganisms have the ability to inhibit the growth and development of plant pathogens, induce the activation of plant defenses, and promote plant growth. Among them, 6-pentyl-alpha-pyrone (6-PP), a ketone produced by Trichoderma fungi, has emerged as a focal point of interest. 6-PP has been isolated and characterized from thirteen Trichoderma species and is the main VOC produced, often accounting for >50% of the total VOCs emitted. This review examines abiotic and biotic interactions regulating the production of 6-PP by Trichoderma, and the known effects of 6-PP on plant pathogens through direct and indirect mechanisms including induced systemic resistance. While there are many reports of 6-PP activity against plant pathogens, the vast majority have been from laboratory studies involving only 6-PP and the pathogen, rather than glasshouse or field studies including a host plant in the system. Biopesticides based on 6-PP may well provide an eco-friendly, sustainable management tool for future agricultural production. However, before this can happen, challenges including demonstrating disease control efficacy in the field, developing efficient delivery systems, and determining cost-effective application rates must be overcome before 6-PP's potential for pathogen control can be turned into reality.

Histidine kinase two-component response regulators Ssk1, Skn7 and Rim15 differentially control growth, developmental and volatile organic compounds emissions as stress responses in Trichoderma atroviride.

The Skn7, Ssk1 and Rim15 proteins are response regulators involved in osmotic, oxidative and nutritional stress in fungi. In order to verify the involvement of these genes in Trichoderma atroviride IMI206040's growth, conidiation, direct antagonism against plant pathogens (Rhizoctonia solani and Sclerotinia sclerotiorum), production of volatile organic compounds (VOCs) with fungistatic effect, and interaction with plants (growth promotion), single mutants were generated, and the phenotypic patterns were analysed in comparison to the wild-type (wt) strain. The mutants were submitted to osmotic, oxidative, membrane and cell wall stress conditions in vitro. The Δskn7 and Δrim15 mutants did not show either significant differences at morphological level, or marked decreases in mycelial growth and conidiation in relation to wt, whereas Δssk1 had altered phenotypes in most conditions tested. The plant-growth promotion of Arabidopsis thaliana seedlings induced by VOCs was not quantitatively modified by any of the mutants in relation to the wt strain, although possible differences in secondary root hairs was noticed for Δrim15. The fungistatic activity was significantly altered for Δssk1 and Δrim15. Overall, the Δssk1 strain showed remarkable morphological differences, with decrease in mycelial growth and conidiation, being also affected in the antagonistic capacity against plant pathogens. The impacts demonstrated by the deletion of ssk1 suggest this gene has a relevant participation in the signalling response to different stresses in T. atroviride and in the interactive metabolism with phytopathogens and plants. On the other hand, unlike other fungal models, Skn7 did not appear to have a critical participation in the above-mentioned processes; Rim15 seemed to confirm its involvement in modulating cellular responses to nutritional status, although with a possible cross-talk with other cellular processes. Our results suggest that Ssk1 likely plays a key regulatory role, not only in basic metabolisms of T. atroviride, but also in biocontrol-related characteristics.

Derrame pleural y colesterol: diferenciación entre exudados y trasudados / Pleural fluid and cholesterol: differentiation of transudates and exudates

En nuestro trabajo de tipo prospectivo fueron estudiados 44 pacientes con derrame pleural, admitidos en el Hospital Universitario de Caracas, entre los meses de Mayo y Octubre de 1989; el diagnóstico correcto de derrame pleural fue etablesido por examen físico, radiología convencional de tórax (PA, lateral, decúbito lateral), ultrasonido, toracocentesis y demás exámenes específicos, ejem.: biopsia pleural.Se obtuvo muestras del líquido pleural en todos los casos, mediante toracocentesis; siendo evaluados sólo los resultados de la primera toracocentesis. Los pacientes fueron ubicados en dos categorías diagnósticas: exudados y trasudados, previa consideración de criterios principales. El 44 pacientes estudiados, 21 hombres (47,72%) y 23 mujeres (52,27%), con edad comprendida entre 19 y 79 años (x=45,7), se obtuvieron los siguientes resultados: 1) Los pacientes con exudado (n = 29), mostraron: a)Contenido proteínico promedio del liquido pleural = 4,71 g/dl ñ 1,43 DE (rango 3,6-5,4); b) Relación proteica líquido pleural/plasma con x = 0,65 ñ 0,5 DE (rango 0,54-0,75); c) Contenido DHL en líquido pleural con x = 921,62 UI ñ 921,62 UI ñ 961 DE; d) Relación DHL en líquido pleural/DHL plasmática con x = 1,52 ñ 1,36 DE; e) Contenido de colesterol total en líquido pleural con x = 86,58 mg/dl ñ 35,15 DE (rango 71-90). n = 15, presentaron: a) Contenido proteico en líquido pleural con x = 2, 04 g/dl ñ 1,09 DE (rango 1,4-2,8); b) Relación proteica líquido pleural/plasma con x = 0,28 ñ 0,14 DE (rango 0,21-0,40); c) Contenido DHL en líquido pleural promedio, resultó = 213,46 UI ñ 131,8 DE; d) Relación DHL líquido pleural/DHL plasmática = 0,42 ñ 0,3 DE; e) Contenido de colesterol total en líquido pleural con x = 22,93 mg/dl ñ 14,2 DE. Conclusiones: Nuestros hallasgos indican que el nivel de colesterol total de 50 mg/dl el líquido pleural tomado como una linea divisoria, diferencia exudados de trasudados (50 mg/dl o más = EXUDADO y menos de 50 mg/dl = TRASUDADO) con una alta significancia estadística (p < 0,001); siendo una ayuda de simple realización, más efectiva y poco costosa, en comparación con las variantes habitualmente utilizadas (proteínas-DHL)

Tetraciclina intrapleural: un método eficaz en el control del derrame pleural maligno recurrente / Intrapleural tetracycline: an effective method in the control of recurrent malignant pleural effusion

Trece (13) pacientes con derrame pleural maligno recibieron administración intrapleural de tetraciclina en solución. A todos los pacientes se lespracticó toracotomía mínima y fueron evaluados con rayos X de tórax postero-anterior y lateral después de la instilación del paciente esclerosante. Los resultados demustran que la tetraciclina es efectiva para el control del derrame pleural maligno recurrente (92,3% de remisión). La morbilidad fue leve, consistiendo principalmente en dolor local (controlado con Meperidina) e hipertemia. La paliación, la mayor calidad de vida, con el mínimo de toxicidad es la meta terapéutica en estos pacientes