Avances en la investigación de la relación patogeno-hospedante y de la resistencia genética a enfermedades de la caña de azúcar en Argentina

Esta contribución presenta avances en la investigación de la variabilidad y resistencia genética con relación a “Roya marrón” y “Estría roja” de la caña de azúcar en Argentina. Resultados experimentales de la inoculación con roya en condiciones controladas permitieron postular que tanto la actividad peroxidasa basal como la tasa de su crecimiento con posterioridad a la infección serían mecanismos complementarios que favorecen la expresión de la resistencia a la enfermedad. También se investigó la diversidad molecular en poblaciones de roya con base en 538 marcadores AFLP a partir de muestreos en diferentes variedades y en una amplia faja de distribución de la enfermedad en el NOA. No se detectaron estructuras genéticas diferenciadas según orígenes, comportándose las diferentes poblaciones como una única gran población indiferenciada de uredosporos con alto grado de variabilidad genética intrínseca. Con relación a Estría roja se logró optimizar una técnica efectiva para el aislamiento, identificación y caracterización genética del agente responsable de la enfermedad. Los resultados obtenidos permitieron confirmar que Acidovorax avenae es el agente responsable de estría roja de la caña de azúcar en Argentina, siendo ésta la primera caracterización realizada en la región cañera para esta patología. Por otra parte el análisis de perfiles de REP-PCR y RAPD confirmó la presencia de al menos cuatro biotipos de la enfermedad en aislados de Salta y Tucumán. La existencia de diversidad genética entre aislamientos permite diseñar estrategias de control mediante el uso de variedades resistentes.The paper presents recent progress in the investigation of variability and genetic resistance in relation to Rust and Red stripe diseases of sugar cane in Argentina. Experimental results for rust innoculation under controlled conditions served to postulate that both basal peroxidase activity and its rate of increase after innoculation with the disease could be complementary mechanisms in the expression of resistance in different cultivars. Molecular diversity of rust populations collected in the field in North West Argentina were also investigated based on 538 AFLP markers. Samples collected in different varieties and sites indicated that rust uredospores populations correspond with a single mixed undifferentiated population with a high degree of intrinsic genetic variability. In regard to Red stripe it was possible to optimize an effective procedure for the isolation, identification and genetic characterization of the disease agent. Results permitted for the first time the identification of Acidovorax avenae as the agent responsible for the disease in Argentina. The profile analysis for REP-PC and RAPD indicated the presence of at least four different biotypes of the disease in Salta and Tucumán. The occurrence of genetic diversity among isolates permits the design of strategies for the control of the disease by means of resistant varieties.Fil: Mariotti, Jorge Alberto. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Machado Assefh, Cristina Renata. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Rech, G.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Fontana, P. D.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Collavino, N. G.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Pocoví, M. I.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Rago, A. M.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Daz, Mirta Elizabeth. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentin

Assessment of plasma chitotriosidase activity, CCL18/PARC concentration and NP-C suspicion index in the diagnosis of Niemann-Pick disease type C: A prospective observational study

Background: Niemann-Pick disease type C (NP-C) is a rare, autosomal recessive neurodegenerative disease caused by mutations in either the NPC1 or NPC2 genes. The diagnosis of NP-C remains challenging due to the non-specific, heterogeneous nature of signs/symptoms. This study assessed the utility of plasma chitotriosidase (ChT) and Chemokine (C-C motif) ligand 18 (CCL18)/pulmonary and activation-regulated chemokine (PARC) in conjunction with the NP-C suspicion index (NP-C SI) for guiding confirmatory laboratory testing in patients with suspected NP-C. Methods: In a prospective observational cohort study, incorporating a retrospective determination of NP-C SI scores, two different diagnostic approaches were applied in two separate groups of unrelated patients from 51 Spanish medical centers (n = 118 in both groups). From Jan 2010 to Apr 2012 (Period 1), patients with =2 clinical signs/symptoms of NP-C were considered ''suspected NP-C'' cases, and NPC1/NPC2 sequencing, plasma chitotriosidase (ChT), CCL18/PARC and sphingomyelinase levels were assessed. Based on findings in Period 1, plasma ChT and CCL18/PARC, and NP-C SI prediction scores were determined in a second group of patients between May 2012 and Apr 2014 (Period 2), and NPC1 and NPC2 were sequenced only in those with elevated ChT and/or elevated CCL18/PARC and/or NP-C SI =70. Filipin staining and 7-ketocholesterol (7-KC) measurements were performed in all patients with NP-C gene mutations, where possible. Results: In total across Periods 1 and 2, 10/236 (4%) patients had a confirmed diagnosis o NP-C based on gene sequencing (5/118 4.2%] in each Period): all of these patients had two causal NPC1 mutations. Single mutant NPC1 alleles were detected in 8/236 (3%) patients, overall. Positive filipin staining results comprised three classical and five variant biochemical phenotypes. No NPC2 mutations were detected. All patients with NPC1 mutations had high ChT activity, high CCL18/PARC concentrations and/or NP-C SI scores =70. Plasma 7-KC was higher than control cut-off values in all patients with two NPC1 mutations, and in the majority of patients with single mutations. Family studies identified three further NP-C patients. Conclusion: This approach may be very useful for laboratories that do not have mass spectrometry facilities and therefore, they cannot use other NP-C biomarkers for diagnosis