Identification of yeast genes that confer resistance to chitosan oligosaccharide (COS) using chemogenomics

Background: Chitosan oligosaccharide (COS), a deacetylated derivative of chitin, is an abundant, and renewable natural polymer. COS has higher antimicrobial properties than chitosan and is presumed to act by disrupting/permeabilizing the cell membranes of bacteria, yeast and fungi. COS is relatively non-toxic to mammals. By identifying the molecular and genetic targets of COS, we hope to gain a better understanding of the antifungal mode of action of COS. Results: Three different chemogenomic fitness assays, haploinsufficiency (HIP), homozygous deletion (HOP), and multicopy suppression (MSP) profiling were combined with a transcriptomic analysis to gain insight in to the mode of action and mechanisms of resistance to chitosan oligosaccharides. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified are involved in processes such as RNA biology (transcription, translation and regulatory mechanisms), membrane functions (e.g. signalling, transport and targeting), membrane structural components, cell division, and proteasome processes. The transcriptomes of control wild type and 5 suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the Ras signal transduction pathway. Down-regulated transcripts included those encoding protein folding components and respiratory chain proteins. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress) and pre-treatment with these well characterized environmental stressors provided little or any resistance to COS. Conclusions: Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane trafficking, provides protection against COS-induced cell membrane permeability and damage. We found that the ARL1 COS-resistant over-expression strain was as sensitive to Amphotericin B, Fluconazole and Terbinafine as the wild type cells and that when COS and Fluconazole are used in combination they act in a synergistic fashion. The gene targets of COS identified in this study indicate that COS’s mechanism of action is different from other commonly studied fungicides that target membranes, suggesting that COS may be an effective fungicide for drug-resistant fungal pathogens.

La palmera datilera y la palmera canaria en la medicina tradicional de España

En la actualidad son muy pocos los usos vigentes. Aunque los dátiles son la materia utilizada con mayor frecuencia, también se han empleado la savia, el polen y el cogollo tierno o palmito. Los dátiles de Phoenix dactylifera se utilizaron como analgésico y para tratar la anemia y trastornos digestivos, o para fortalecer las encías, en el tratamiento de la disfunción eréctil y como afrodisiacos, para facilitar el parto y calmar los dolores postparto, y tratar el prolapso de la matriz o para el exceso de flujo menstrual. También se utilizaron como diuréticos, para la disuria y en trastornos de la vejiga. El uso que más claramente ha persistido es el tratamiento de diversos problemas respiratorios. En uso externo se utilizaron para tratar problemas de la piel, heridas, hemorragias y hemorroides. De la palmera de Canarias (Phoenix canariensis), especialmente en la isla de la Gomera, la savia cruda o guarapo, su concentrado o miel de palma y los resultantes de su fermentación (vino de palma) se consumen como alimento y también se utilizan como diurético, remedio de trastornos génitourinarios, digestivo, para infecciones de la cavidad bucal, expectorante, antitusígeno y para las irritaciones de garganta. En el Toledo de Al-Andalus las espatas de P. dactylifera se utilizaron, hace casi mil años, en el tratamiento de la debilidad, los dolores, nefritis, las enfermedades de la vejiga, trastornos hepáticos (también como preventivo), diarrea, trastornos digestivos, dolores en el abdomen y en el estómago, excesivo sangrado menstrual, úlceras en la piel y sarna, dolores articulares y trastornos cardiacos. La fitoterapia racional debería prestar atención a este recurso, considerar la evidencia científica disponible (farmacológica e incluso clínica) e incorporarlo a nuestro repertorio terapéutico.