Effects of sublethal doses of methoxyfenozide on the development, survival and reproduction of Spodoptera frugiperda.

The lethal and sublethal effects of the ecdysone agonist methoxyfenozide on the fall armyworm, Spodoptera frugiperda (J. E. Smith), were investigated by feeding a methoxyfenozide-treated diet to ��ifth instars until pupation in doses corresponding to the LC 10 and LC 25 for the compound. Larval mortality reached 8% and 26% in the low and high concentration groups, respectively, on the seventh day of the experiment. A progressive larval mortality of 12% for the LC 10 and 60% for the LC 25 was observed before pupation. Treated larvae exhibited lower pupal weights, higher pupal mortality, presence of deformed pupae, and more deformed adults than untreated larvae. The incorporation of methoxyfenozide into the diet had a signi��icant effect on the timing of larval development. The development period for males and females was about seven days longer than the controls for both concentrations tested. In contrast, the compound affected neither pupae nor adult longevity. Finally, S. frugiperda adults that resulted from ��ifth instars treated with methoxyfenozide were not affected in their mean cumulative number of eggs laid per female (fecundity), nor percentages of eggs hatched (fertility), or the sex ratio. Our results suggest that the combination of lethal and sublethal effects of methoxyfenozide may have important implications for the population dynamics of the fall armyworm

Sensitization profiles and cross-reactivity among plant allergens. Molecular mechanisms of food allergy development and the role of enhancers

La prevalencia de las alergias est�� aumentando desde mediados del siglo XX, y se estima que actualmente afectan a alrededor del 2-8 % de la poblaci��n, pero las causas de este aumento a��n no est��n claras. Encontrar el origen del mecanismo por el cual una prote��na inofensiva se convierte en capaz de inducir una respuesta al��rgica es de vital importancia para prevenir y tratar estas enfermedades. Aunque la caracterizaci��n de al��rgenos relevantes ha ayudado a mejorar el manejo cl��nico y a aclarar los mecanismos b��sicos de las reacciones al��rgicas, todav��a queda un largo camino para establecer el origen de la alergenicidad y reactividad cruzada. El objetivo de esta tesis ha sido caracterizar las bases moleculares de la alergenicidad tomando como modelo dos familias de panalergenos (prote��nas de transferencia de l��pidos ���LTPs- y taumatinas ���TLPs-) y estudiando los mecanismos que median la sensibilizaci��n y la reactividad cruzada para mejorar tanto el diagn��stico como el tratamiento de la alergia. Para ello, se llevaron a cabo dos estrategias: estudiar la reactividad cruzada de miembros de familias de panal��rgenos; y estudiar mol��culas-co-adyuvantes que pudieran favorecer la capacidad alerg��nica de dichas prote��nas. Para estudiar la reactividad cruzada entre miembros de la misma familia de prote��nas, se seleccionaron LTPs y TLPs, descritas como alergenos, tomando como modelo la alergia a frutas. Por otra parte, se estudiaron los perfiles de sensibilizaci��n a al��rgenos de trigo relacionados con el asma del panadero, la enfermedad ocupacional m��s relevante de origen al��rgico. Estos estudios se llevaron a cabo estandarizando ensayos tipo microarrays con al��rgenos y analizando los resultados por la teor��a de grafos. En relaci��n al estudiar mol��culas-co-adyuvantes que pudieran favorecer la capacidad alerg��nica de dichas prote��nas, se llevaron a cabo estudios sobre la interacci��n de los al��rgenos alimentarios con c��lulas del sistema inmune humano y murino y el epitelio de las mucosas, analizando la importancia de mol��culas co-transportadas con los al��rgenos en el desarrollo de una respuesta Th2. Para ello, Pru p 3(LTP y al��rgeno principal del melocot��n) se selecci��n como modelo para llevarlo a cabo. Por otra parte, se analiz�� el papel de mol��culas activadoras del sistema inmune producidas por pat��genos en la inducci��n de alergias alimentarias seleccionando el modelo kiwi-alternaria, y el papel de Alt a 1, al��rgeno mayor de dicho hongo, en la sensibilizaci��n a Act d 2, al��rgeno mayor de kiwi. En resumen, el presente trabajo presenta una investigaci��n innovadora aportando resultados de gran utilidad tanto para la mejora del diagn��stico como para nuevas investigaciones sobre la alergia y el esclarecimiento final de los mecanismos que caracterizan esta enfermedad. ABSTRACT Allergies are increasing their prevalence from mid twentieth century, and they are currently estimated to affect around 2-8% of the population but the underlying causes of this increase remain still elusive. The understanding of the mechanism by which a harmless protein becomes capable of inducing an allergic response provides us the basis to prevent and treat these diseases. Although the characterization of relevant allergens has led to improved clinical management and has helped to clarify the basic mechanisms of allergic reactions, it seems justified in aspiring to molecularly dissecting these allergens to establish the structural basis of their allergenicity and cross-reactivity. The aim of this thesis was to characterize the molecular basis of the allergenicity of model proteins belonging to different families (Lipid Transfer Proteins ���LTPs-, and Thaumatin-like Proteins ���TLPs-) in order to identify mechanisms that mediate sensitization and cross reactivity for developing new strategies in the management of allergy, both diagnosis and treatment, in the near future. With this purpose, two strategies have been conducted: studies of cross-reactivity among panallergen families and molecular studies of the contribution of cofactors in the induction of the allergic response by these panallergens. Following the first strategy, we studied the cross-reactivity among members of two plant panallergens (LTPs , Lipid Transfer Proteins , and TLPs , Thaumatin-like Proteins) using the peach allergy as a model. Similarly, we characterized the sensitization profiles to wheat allergens in baker's asthma development, the most relevant occupational disease. These studies were performed using allergen microarrays and the graph theory for analyzing the results. Regarding the second approach, we analyzed the interaction of plant allergens with immune and epithelial cells. To perform these studies , we examined the importance of ligands and co-transported molecules of plant allergens in the development of Th2 responses. To this end, Pru p 3, nsLTP (non-specific Lipid Transfer Protein) and peach major allergen, was selected as a model to investigate its interaction with cells of the human and murine immune systems as well as with the intestinal epithelium and the contribution of its ligand in inducing an allergic response was studied. Moreover, we analyzed the role of pathogen associated molecules in the induction of food allergy. For that, we selected the kiwi- alternaria system as a model and the role of Alt a 1 , major allergen of the fungus, in the development of Act d 2-sensitization was studied. In summary, this work presents an innovative research providing useful results for improving diagnosis and leading to further research on allergy and the final clarification of the mechanisms that characterize this disease.

Distinct and conserved transcriptomic changes during nematode-induced giant cell development in tomato compared with Arabidopsis: a functional role for gene repression

Root-knot nematodes (RKNs) induce giant cells (GCs) from root vascular cells inside the galls. Accompanying molecular changes as a function of infection time and across different species, and their functional impact, are still poorly understood. Thus, the transcriptomes of tomato galls and laser capture microdissected (LCM) GCs over the course of parasitism were compared with those of Arabidopsis, and functional analysis of a repressed gene was performed. Microarray hybridization with RNA from galls and LCM GCs, infection-reproduction tests and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) transcriptional profiles in susceptible and resistant (Mi-1) lines were performed in tomato. Tomato GC-induced genes include some possibly contributing to the epigenetic control of GC identity. GC-repressed genes are conserved between tomato and Arabidopsis, notably those involved in lignin deposition. However, genes related to the regulation of gene expression diverge, suggesting that diverse transcriptional regulators mediate common responses leading to GC formation in different plant species. TPX1, a cell wall peroxidase specifically involved in lignification, was strongly repressed in GCs/galls, but induced in a nearly isogenic Mi-1 resistant line on nematode infection. TPX1 overexpression in susceptible plants hindered nematode reproduction and GC expansion. Time-course and cross-species comparisons of gall and GC transcriptomes provide novel insights pointing to the relevance of gene repression during RKN establishment.