IDENTIFICATION OF RHIZOSPHERIC AND ENDOPHYTIC DIAZOTROPHIC BACTERIA ASSOCIATED TO Lycopersicon esculentum Mill FROM THE NORTE OF SANTANDER, COLOMBIA

Las bacterias diazotróficas pueden estimular el crecimiento del cultivo del tomate (Lycopersicon esculentum Mill.) mediante la síntesis de hormonas, fijación de N y producción de sideróforos, u otros procesos. Las bacterias diazotróficas predominantes en los agroecosistemas pueden ser biofertilizantes potenciales. El objetivo del estudio fue cuantificar y caracterizar la población de bacterias diazotróficas rizosféricas en muestras de suelo rizosférico (SR) y bacterias diazotróficas endófitas en muestras de raíces (R) y material foliar (MF), mediante pruebas fenotípicas y moleculares. El estudio fue exploratorio y con un muestreo aleatorio, con 18 muestras SR, raíces (R) y MF de cultivos de tomate en seis fincas. Las diferencias en el número más probable (NMP) de bacterias diazotróficas no fueron significativas entre los sitios de las muestras de MF y R. La media de NFb mostró diferencias altamente significativas en Azotobacter sp. y Azospirillum sp. entre las muestras de SR, R y MF, con un NMP mayor y menor en SR y MF. Esto se relaciona con la caracterización fenotípica y bioquímica de SR donde se identificaron 14 aislados como Azotobacter sp. y siete como Azospirillum sp. Los géneros Burkholderia y Gluconacetobacter no mostraron diferencias significativas en el número de aislados entre muestras de SR y R, pero sí respecto a MF, con la población celular menor. Las diferencias entre las fincas no fueron significativas en las variables del suelo relacionadas con la disimilitud de NMP. La caracterización molecular permitió identificar A. chroococcum, A. nigricans, A. vinelandii, A. brasilense, B. glumae y G. azotocaptans/G. johannae en muestras de SR; B. glumae, G. azotocaptans/G. johannae en muestras de R y G. azotocaptans/G. johannae en muestras de MF.Diazotrophic bacteria can stimulate the growth of the tomato (Lycopersicon esculentum Mill.) crop by hormone synthesis, with N fixation and the production of siderophores, or other processes. The predominant diazotrophic bacteria in agroecosystems may be potential biofertilizers. The aim of this study was to quantify and characterize the population of rhizospheric diatrophic bacteria in samples of rhizospheric soil (RS) and endophytic diazotrophic bacteria in root (R) and foliar material (FM) samples, with phenotypical and molecular tests. The study was exploratory and with random sampling, with 18 RS, roots (R) and FM samples of tomato plantations in six farms. The differences in the most probable number (MPN) of diazotrophic bacteria were not significant between the FM and R sampling sites. The mean of the Mfb displayed highly significant differences in Azotobacter sp. and Azospirillum sp. between the RS, R and FM samples, with a higher and lower MPN in RS and FM. This relates with the phenotypical and biochemical characterization of RS, in which 14 isolations were identified as Azotobacter sp., and seven as Azospirillum sp. The genera Burkholderia and Gluconacetobacter showed no significant differences in the number of isolations between RS and R samples, but they did with FM, with the lower cell population. The differences between the farms were not significant in the soil parameters, related to the dissimilarity of the MPN. Molecular characterization helped identify A. chroococcum, A. nigricans, A. vinelandii, A. brasilense, B. glumae and G. azotocaptans/G. johannae in samples of RS; B. glumae, G. azotocaptans/G. johannae in samples of R and G. azotocaptans/G. johannae in FM sample

Defining inflammatory cell states in rheumatoid arthritis joint synovial tissues by integrating single-cell transcriptomics and mass cytometry.

To define the cell populations that drive joint inflammation in rheumatoid arthritis (RA), we applied single-cell RNA sequencing (scRNA-seq), mass cytometry, bulk RNA sequencing (RNA-seq) and flow cytometry to T cells, B cells, monocytes, and fibroblasts from 51 samples of synovial tissue from patients with RA or osteoarthritis (OA). Utilizing an integrated strategy based on canonical correlation analysis of 5,265 scRNA-seq profiles, we identified 18 unique cell populations. Combining mass cytometry and transcriptomics revealed cell states expanded in RA synovia: THY1(CD90)+HLA-DRAhi sublining fibroblasts, IL1B+ pro-inflammatory monocytes, ITGAX+TBX21+ autoimmune-associated B cells and PDCD1+ peripheral helper T (TPH) cells and follicular helper T (TFH) cells. We defined distinct subsets of CD8+ T cells characterized by GZMK+, GZMB+, and GNLY+ phenotypes. We mapped inflammatory mediators to their source cell populations; for example, we attributed IL6 expression to THY1+HLA-DRAhi fibroblasts and IL1B production to pro-inflammatory monocytes. These populations are potentially key mediators of RA pathogenesis