The Pattern Recognition Receptor FLS2 Can Shape the Arabidopsis Rhizosphere Microbiome ß-Diversity but Not EFR1 and CERK1.

Pathogen associated molecular pattern (PAMP) triggered immunity (PTI) is the first line of plant defense. We hypothesized that the absence of pattern recognition receptors (PRRs) in plants could influence the rhizosphere microbiome. Here, we report sequencing of the 16S ribosomal RNA gene and the fungal ribosomal RNA internal transcribed spacer region of rhizosphere DNA from three Arabidopsis PRR mutants involved in plant innate immunity (efr1, fls2, and cerk1). We conducted experiments in a growth chamber using native soil from the Red River Farm (Terral, OK, USA) to detect microbial community shifts in the rhizosphere that may occur in the absence of PRR receptors compared to wild-type (WT; Col-0) plants. No difference in the α-diversity of the rhizosphere microbial population was observed between the PRR mutants tested and the WT. Plant host genotype had a significant impact in bacterial ß-diversity only between the fls2 mutant and the WT. Surprisingly, no significant changes in fungal ß-diversity were observed between the PRR mutants and WT, although we observed an increase in relative abundance for the cup fungi (Pezizaceae) in the cerk1 mutant. This finding suggests that the FLS2 receptor can modulate the rhizosphere-associated microbiome ß-diversity and expands the list of current known genotypes that can modulate the rhizosphere microbiota.

Dark Respiration Measurement from Arabidopsis Shoots.

Dark respiration refers to experimental measures of leaf respiration in the absence of light, done to distinguish it from the photorespiration that occurs during photosynthesis. Dark aerobic respiration reactions occur solely in the mitochondria and convert glucose molecules from cytoplasmatic glycolysis and oxygen into carbon dioxide and water, with the generation of ATP molecules. Previous methods typically use oxygen sensors to measure oxygen depletion or complicated and expensive photosynthesis instruments to measure CO2 accumulation. Here, we provide a detailed, step-by-step approach to measure dark respiration in plants by recording CO2 fluxes of Arabidopsis shoot and root tissues. Briefly, plants are dark acclimated for 1 hour, leaves and roots are excised and placed separately in airtight chambers, and CO2 accumulation is measured over time with standard infrared gas analyzers. The time-series data is processed with R scripts to produce dark respiration rates, which can be standardized by fresh or dry tissue mass. The current method requires inexpensive infrared gas analyzers, off-the-shelf parts for chambers, and publicly available data analysis scripts.

Evolución del concepto de lepra e instituciones en Colombia / Evolution of the concept of leprae and institutions in Colombia

Este trabajo refleja la evolución del concepto de lepra que dependió de circunstancias históricas determinadas y estrechamente relacionadas con el manejo institucional. Notamos que a pesar de los avances científicos no se ha logrado determinar muchos aspectos de la enfermedad tan importantes como los postulados de Koch. Desde los leprocomios iniciales, con los cuales se intentó solucionar el problema de salud pública que reemplazaba la lepra hasta el manejo individualizado, integral y ambulatorio actúal, se evidencia una inadecuada e irregular enfoque del problema que da como resultado en que su control no haya sido el esperado y que aún en el momento no se cuente con una estadística veráz acerca de la mágnitud del mismo en el País