Project description:Phytoplasma, an emerging plant pathogen is an endocellular obligate parasite of plant phloem tissues with highly reduced genomes and low GC content. They contain a minimal set of genes essential for survival as an intracellular parasite. The role of G-Quadruplexes in pathogenicity has been reported in a variety of microbial pathogens. Detailed investigation on the genome wide occurrence and distribution of Putative G-Quadruplex forming Sequences (PGQSs) in the AT-rich genome of Onion yellows phytoplasma (strain OY-M) was carried out. Relative enrichment and depletion of these putative secondary structures in different genomic regions of OY-M was investigated with an aim to unravel their association with functionally important genomic locations. PGQSs density of 0.4407/Kbp was detected in the genome of OY-M phytoplasma, which is significantly higher than the average PGQSs density (0.136/Kbp) reported for other members of its phylum, namely Tenericutes. A non-random distribution of PGQSs across the length of the genome was observed. Putative promoter regions of OY-M were found to be particularly enriched in PGQSs followed by genic regions. The repeat rich regions were identified to have minimum PGQSs density. Presence of PGQSs in important genes such as those involved in secretory pathways of virulent factors, transport related functions, rRNA and tRNA was particularly intriguing. Our study reports for the first time a detailed investigation on the genome-wide locations of putative G-Quadruplexes in phytoplasma and highlights the need to further investigate their role in the metabolism and also in the mechanism of pathogenicity.
Project description:Background: Human intestinal tissue samples are barely accessible to study potential health benefits of nutritional compounds. Numbers of animals used in animal trials, however, need to be minimalized. Therefore, in this study we explored the applicability of an in vitro model, namely human intestinal Caco-2 cells, to study the effect of food compounds on (intestinal) health. In vitro digested yellow (YOd) and white onion extracts (WOd) were used as model food compounds and transcriptomics was applied to obtain more insight into their mode of actions in the intestinal cells. Methods: Caco-2 cells were incubated with in vitro digested onion extracts for 6 hours, total RNA was extracted and Affymterix Human Gene 1.1 ST arrays were used to analyze the gene expression profiles. To identify onion-induced gene expression profiles in Caco-2 cells, digested yellow onion and white onion samples were compared to a digest control samples. Results: We found that yellow onion (n=5586, p<0.05) had a more pronounced effect on gene expression than white onion (n=3688, p<0.05). However, a substantial number of genes (n=3281, p<0.05) were affected by both onion variants in the same direction. Pathway analyses revealed that mainly processes related to oxidative stress, and especially the Keap1-Nrf2 pathway, were affected by onions. Our data fit with previous in vivo studies showing that the beneficial effects of onions are mostly linked to their antioxidant properties. Conclusion: our data indicate that the in vitro Caco-2 intestinal model can be used to determine modes of action of nutritional compounds and can thereby reduce the number of animals used in conventional nutritional intervention studies.
Project description:Rat small intestine precision cut slices were exposed for 6 hours to in vitro digested yellow (YOd) or white onion extracts (WOd) that was followed by transcriptomics analysis. The digestion was performed to mimic the digestion that in vivo takes place in the saliva, stomach and small intestine. A main question was to which extent the outcome of the biological interpretation of the transcription analysis (pathway analysis) depend on the model used. One outcome was that mainly processes related to oxidative stress, and especially the Keap1-Nrf2 pathway, were affected by onions in all three models.