Summary Differences in the activity of monocytes/macrophages, important target cells of Mycobacterium tuberculosis, might influence tuberculosis progression. With the purpose of identifying candidate genes for tuberculosis susceptibility we infected monocytes from both healthy elderly individuals (a tuberculosis susceptibility group) and elderly tuberculosis patients with M. tuberculosis, and performed a microarray experiment. We detected 78 differentially expressed transcripts and confirmed these results by quantitative PCR of selected genes. We found that monocytes from tuberculosis patients showed similar expression patterns for these genes, regardless of whether they were obtained from younger or older patients. Only one of the detected genes corresponded to a cytokine: IL26, a member of the interleukin‐10 (IL‐10) cytokine family which we found to be down‐regulated in infected monocytes from tuberculosis patients. Non‐infected monocytes secreted IL‐26 constitutively but they reacted strongly to M. tuberculosis infection by decreasing IL‐26 production. Furthermore, IL‐26 serum concentrations appeared to be lower in the tuberculosis patients. When whole blood was infected, IL‐26 inhibited the observed pathogen‐killing capability. Although lymphocytes expressed IL26R, the receptor mRNA was not detected in either monocytes or neutrophils, suggesting that the inhibition of anti‐mycobacterial activity may be mediated by lymphocytes. Additionally, IL‐2 concentrations in infected blood were lower in the presence of IL‐26. The negative influence of IL‐26 on the anti‐mycobacterial activity and its constitutive presence in both serum and monocyte supernatants prompt us to propose IL26 as a candidate gene for tuberculosis susceptibility.

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Walnuts are considered recalcitrant to tissue culture, with a great genetic determinism on all stages of micropropagation; while other factors, also with great impact, become more complicated with the reproduction of newly realized varieties. In this research, a holistic approach aimed to determine the influence of genotype and the nutritive formulation throughout the whole cycle of micropropagation of four Persian walnut varieties (Juglans regia L.) was presented. During the in vitro establishment it was determined that besides genotype and culture medium, the effect of collection season and the likely interaction amongst factors had a great influence on the successful introduction of all four genotypes. However, all cultures were affected by a deep decay, being necessary the introduction of ethylenediamine di-2-hydroxyphenyl acetate ferric, as iron source, and Phloroglucinol in both Murashige and Skoog (1962) and the corrected Driver and Kuniyuki (1987) formulations. These modifications allowed the stabilization of cultures, maintaining thereafter a steady quality. Either proliferation, rooting and ex vitro survival of four clones were affected by the culture medium, obtaining the best results with the corrected Driver and Kuniyuki (1987) formulation. Finally, in vitro plants produced from all clones were acclimated with high survival rates (75.9–91.1% for the best culture medium), depending of clone and the culture medium used. Microsatellite analysis showed that micropropagated plants maintained the same genetic profiles of their corresponding donor trees. These results might contribute to deepening of the understanding of factors that determine the success of micropropagation of walnuts, and the extents of its influence; whereas, it sets the basis for the commercial micropropagation of all four clones.

The whole blood model for infection has proven useful to analyze the immunological response to Mycobacterium tuberculosis, because it exerts a significant antimicrobial activity. Although this activity has been generally assumed to be cellular, we have found that the leukocyte fraction of blood from healthy volunteers did not kill the bacilli. We have discovered that plasma was responsible for a large proportion, but not all, of the antimicrobial activity. Furthermore, infected monocytes controlled the mycobacterial multiplication when cultivated in the presence of plasma. Intriguingly, serum from the same donors did not share this activity, although it was able to eliminate the non-pathogenic Mycobacterium gordonae To identify the remaining components that participate in the antimycobacterial activity we fractionated blood in leukocytes, plasma, erythrocytes and platelets, and analyzed the bactericidal power of each fraction and their combinations using a factorial design. We found that erythrocytes, but not platelets, participated and showed by flow cytometry that mycobacteria physically associated with erythrocytes. We propose that in exposed healthy individuals that show 'early clearance' of the mycobacteria, the innate response is predominantly humoral, probably through the effect of antimicrobial peptides and proteins.

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