PI4KIIIß Activity Regulates Lateral Root Formation Driven by Endocytic Trafficking to the Vacuole.

Lateral roots (LRs) increase the contact area of the root with the rhizosphere and thereby improve water and nutrient uptake from the soil. LRs are generated either via a developmentally controlled mechanism or through induction by external stimuli, such as water and nutrient availability. Auxin regulates LR organogenesis via transcriptional activation by an auxin complex receptor. Endocytic trafficking to the vacuole positively regulates LR organogenesis independently of the auxin complex receptor in Arabidopsis (Arabidopsis thaliana). Here, we demonstrate that phosphatidylinositol 4-phosphate (PI4P) biosynthesis regulated by the phosphatidylinositol 4-kinases PI4KIIIß1 and PI4KIIIß2 is essential for the LR organogenesis driven by endocytic trafficking to the vacuole. Stimulation with Sortin2, a biomodulator that promotes protein targeting to the vacuole, altered PI4P abundance at both the plasma membrane and endosomal compartments, a process dependent on PI4K activity. These findings suggest that endocytic trafficking to the vacuole regulated by the enzymatic activities of PI4KIIIß1 and PI4KIIIß2 participates in a mechanism independent of the auxin complex receptor that regulates LR organogenesis in Arabidopsis. Surprisingly, loss-of-function of PI4KIIIß1 and PI4KIIIß2 induced both LR primordium formation and endocytic trafficking toward the vacuole. This LR primordium induction was alleviated by exogenous PI4P, suggesting that PI4KIIIß1 and PI4KIIIß2 activity constitutively negatively regulates LR primordium formation. Overall, this research demonstrates a dual role of PI4KIIIß1 and PI4KIIIß2 in LR primordium formation in Arabidopsis.

Falla de tratamiento en neumonía adquirida en la comunidad: coccidioidomicosis en un viajero / Treatment failure in community-adquired pneumonia: coccidioidomycosis in a traveler patient

Treatment failure in community-acquired pneumonia is defined as a clinical condition with inadequate response to antimicrobial therapy. Resistant and unusual microorganisms and noninfectious causes are responsible for treatment failure. Coccidioides immitis is a fungus that causes pneumonia in the northern hemisphere, especially in the United States and northern Mexico. We report a case of pulmonary coccidioidomycosis imported from Mexico to Chile. After a comprehensive study, histopathology was able to establish Coccidiodes immitis as the causative agent, achieving clinical and radiological improvement with antifungal therapy.

La neumonía de evolución tórpida son aquellas en que no se logra una respuesta clínica adecuada con el uso de terapia antimicrobiana. Existen múltiples causas a esta falta de respuesta: resistencia antimicrobiana, microorganismos no cubiertos o infecciones por microorganismos atípicos. Coccidioides immitis es un hongo causante de neumonía en el hemisferio norte, especialmente en E.U.A y norte de México. No existen reportes de casos pulmonares importados en Chile. Presentamos el caso de una mujer adulta con una neumonía que no respondió al tratamiento antimicrobiano habitual. Una vez realizado un estudio exhaustivo, se logró establecer mediante el estudio histopatológico la existencia de una coccidiodomicosis como entidad causal, logrando una respuesta clínica y radiológica favorable al tratamiento antifúngico.