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Fil: Gutiérrez Córdoba, Elkin Andrés. Universidad de Buenos Aires. Facultad de Ciencias Económicas

La hoja blanca del arroz es una de las enfermedades más importantes del cultivo del arroz en América. El agente causal es el Virus de la hoja blanca del arroz (RHBV), el cual es transmitido por el insecto Tagosodes orizicolus, conocido como Sogata. Los estudios sobre la genética de la resistencia a esta enfermedad han sido escasos, tanto que, hasta el momento, sólo se conoce un QTL en la variedad Fedearroz 2000. En el presente estudio se realizó la identificación de loci de rasgos cuantitativos (QTL) asociados a la resistencia al RHBV, en tres poblaciones biparentales F2:3 derivadas del cruzamiento de las accesiones resistentes WAS 208-B-B-5-1-1-3, Badkalamkati y PTB 25, con la variedad susceptible Bluebonnet 50. A través de la evaluación en invernadero, de la severidad y la incidencia de la enfermedad, se identificaron cinco QTL de resistencia sobre los cromosomas cuatro, seis y once, nombrados qHBV4.1, qHBV4.2WAS, qHBV6.1PTB, qHBV11.1 y qHBV11.2. Los QTL qHBV4.1 y qHBV11.1 fueron los que tuvieron el mayor efecto sobre la incidencia y la severidad, respectivamente. En adición, se identificaron dos QTL de susceptibilidad sobre los cromosomas nueve y diez en el parental PTB 25. Estos resultados aportan al entendimiento de las bases genéticas de la resistencia y permitirán desarrollar estrategias de mejoramiento molecular basado en los marcadores ligados a estos QTL. //Abstract: Rice hoja blanca is one of the most serious diseases in rice growing areas in America. Its causal agent is the Rice hoja blanca virus (RHBV), which is transmitted by the insect Tagosodes orizicolus, known as Sogata. Genetic studies about the disease resistance are so scarce that, so far, only one major QTL has been reported in Fedearroz 2000, the most resistant variety in Colombia. In the present study we performed the identification of quantitate trait loci (QTL) associated with RHBV resistance using three F2:3 populations derived from the cross of the resistant varieties WAS 208-B-B-5-1-1-3, Badkalamkati and PTB 25, with the high susceptible variety Bluebonnet 50. Based on the disease severity and incidence evaluation in greenhouse, we identified five QTL for RHBV resistance on chromosomes four, six and eleven. These QTL were named qHBV4.1, qHBV4.2WAS, qHBV6.1PTB, qHBV11.1 and qHBV11.2. The QTL qHBV4.1 and qHBV11.1 had the largest effects for incidence and severity, respectively. In addition, we identified two QTL of susceptibility on chromosomes nine and ten in the PTB 25 genotype. These results provide a better understanding of the genetic bases of RHBV resistance, and may be used to develop molecular breeding strategies to improve RHBV resistance based on markers linked to these QTL. Línea de Investigación: Fitomejoramiento Solicito que este documento de tesis no sea visible en texto completo hasta el año 2020, dado que se está preparando un artículo científico para ser publicado. Maestría

2082-02 Embargo por política editorial The efficacy and safety of two polyvalent horse-derived antivenoms in Bothrops asper envenomings were tested in a randomized, double-blind, clinical trial performed in Colombia. Both antivenoms were manufactured from the same pool of hyperimmune plasma. Antivenom A was made of F(ab′)2 fragments, generated by pepsin digestion and caprylic acid precipitation, whereas antivenom B consisted of whole IgG molecules produced by caprylic acid precipitation followed by ion-exchange chromatography. Besides the different nature of the active substance, antivenom B had higher protein concentration, slightly higher turbidity and aggregate content. No significant differences were observed in the efficacy of antivenoms. Both halted local and systemic bleeding (P = 0.40) within 6–12 h of treatment in 100% of the cases, and restored blood coagulation (P = 0.87) within 6–24 h in 84.7% of patients, and within 48 h in all of them, in agreement with restoration of plasma fibrinogen concentration. Venom concentrations in serum dropped significantly (P < 0.001), to very low levels, 1 h after antivenom infusion. Nevertheless, eight patients (11.1%), four for each antivenom, presented recurrence of venom antigenaemia at different times, from 6 to 96 h, with clinical significance (recurrent coagulopathy) only in one group B patient (2.9%). Serum creatine kinase (CK) activity was increased, as a consequence of local myonecrosis. There was no significant difference (P = 0.51) in the incidence of early adverse reactions to antivenom administration (28.9% for patients of group A and 20.6% for patients of group B), most of the reactions being mild, mainly cutaneous. The most frequent complications were cellulitis (16.7%), abscess formation (5.6%), acute renal failure (8.3%), and compartmental syndrome (5.6%). In conclusion, IgG and F(ab′)2 antivenoms, prepared by caprylic acid fractionation, presented similar efficacy and safety profiles for the treatment of B. asper envenomings in Colombia. Instituto Colombiano para el Desarrollo de la Ciencia y la Tecnología Francisco José de Caldas//Colciencias/Colombia Universidad de Antioquia///Colombia Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo/[206AC0281]/CYTED/España Universidad de Costa Rica/[741-A9-003]/UCR/Costa Rica UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP)