The dietary specialist fruit fly Drosophila sechellia has evolved to specialize on the toxic fruit of its host plant Morinda citrifolia. Toxicity of Morinda fruit is primarily due to high levels of octanoic acid (OA). Using RNA interference (RNAi), prior work found that knockdown of Osiris family genes Osiris 6 (Osi6), Osi7, and Osi8 led to increased susceptibility to OA in adult D. melanogaster flies, likely representing genes underlying a Quantitative Trait Locus (QTL) for OA resistance in D. sechellia. While genes in this major effect locus are beginning to be revealed, prior work has shown at least five regions of the genome contribute to OA resistance. Here, we identify new candidate OA resistance genes by performing differential gene expression analysis using RNA-sequencing (RNA-seq) on control and OA-exposed D. sechellia flies. We found 104 significantly differentially expressed genes with annotated orthologs in D. melanogaster, including six Osiris gene family members, consistent with previous functional studies and gene expression analyses. Gene ontology (GO) term enrichment showed significant enrichment for cuticle development in upregulated genes and significant enrichment of immune and defense responses in downregulated genes, suggesting important aspects of the physiology of D. sechellia that may play a role in OA resistance. In addition, we identified five candidate OA resistance genes that potentially underlie QTL peaks outside of the major effect region, representing promising new candidate genes for future functional studies.

To successfully colonize host tissues, bacteria must respond to and detoxify many different host-derived antimicrobial compounds, such as nitric oxide (NO). NO has direct antimicrobial activity through attack on iron-sulfur (Fe-S) cluster-containing proteins. NO detoxification plays an important role in promoting bacterial survival, but it remains unclear if repair of Fe-S clusters is also important for bacterial survival within host tissues. Here we show that the Fe-S cluster repair protein YtfE contributes to the survival of Yersinia pseudotuberculosis within the spleen following nitrosative stress. Y. pseudotuberculosis forms clustered centers of replicating bacteria within deep tissues, where peripheral bacteria express the NO-detoxifying gene hmp. ytfE expression also occurred specifically within peripheral cells at the edges of microcolonies. In the absence of ytfE, the area of microcolonies was significantly smaller than that of the wild type (WT), consistent with ytfE contributing to the survival of peripheral cells. The loss of ytfE did not alter the ability of cells to detoxify NO, which occurred within peripheral cells in both WT and ΔytfE microcolonies. In the absence of NO-detoxifying activity by hmp, NO diffused across ΔytfE microcolonies, and there was a significant decrease in the area of microcolonies lacking ytfE, indicating that ytfE also contributes to bacterial survival in the absence of NO detoxification. These results indicate a role for Fe-S cluster repair in the survival of Y. pseudotuberculosis within the spleen and suggest that extracellular bacteria may rely on this pathway for survival within host tissues.

Iron-sulfur cluster repair contributes to Y. pseudotuberculosis survival within deep tissues. 1 2 3 Running title: Iron-sulfur cluster repair during Y. pseudotuberculosis infection 4 5 6 7 Abstract 24To successfully colonize host tissues, bacteria must respond to and detoxify many different host-25 derived antimicrobial compounds, such as nitric oxide (NO). NO can directly kill bacteria, 26 primarily through attack on iron-sulfur (Fe-S) cluster-containing proteins. NO detoxification 27 plays an important role in promoting bacterial survival, but it remains unclear if repair of Fe-S 28 clusters is also important for bacterial survival within host tissues. Here we show that the Fe-S 29 cluster repair protein, YtfE, contributes to the survival of Y. pseudotuberculosis within the spleen 30 following nitrosative stress. Y. pseudotuberculosis forms clustered centers of replicating bacteria 31 within deep tissues, where peripheral bacteria express the NO-detoxifying gene, hmp. ytfE 32 expression also occurred specifically within peripheral cells at the edges of microcolonies. In the 33 absence of ytfE, the area of microcolonies was significantly smaller than WT, consistent with 34 ytfE contributing to the survival of peripheral cells. The loss of ytfE did not alter the ability of 35 cells to detoxify NO, which occurred within peripheral cells in both WT and ∆ytfE 36 microcolonies. In the absence of NO-detoxifying activity by hmp, NO diffused across ∆ytfE 37 microcolonies, and there was a significant decrease in the area of microcolonies lacking ytfE, 38indicating that ytfE also contributes to bacterial survival in the absence of NO detoxification. 39These results indicate a role for Fe-S cluster repair in the survival of Y. pseudotuberculosis 40 within the spleen, and suggest that extracellular bacteria may rely on this pathway for survival 41 within host tissues. 42

ObjectivesThere is emerging interest and data supporting the effectiveness of community health workers (CHWs) in non-communicable diseases (NCDs) in low/middle-income countries (LMICs). This study aimed to determine whether a CHW-led intervention targeting diabetes and hypertension could improve markers of clinical disease control in rural Mexico.Design and settingA prospective observational stepped-wedge study was conducted across seven communities in rural Chiapas, Mexico from March 2014 to April 2018.Participants149 adults with hypertension and/or diabetes.InterventionThis study was conducted in the context of the programmatic roll-out of an accompaniment-based CHW-led intervention designed to complement comprehensive primary care for adults with diabetes and/or hypertension. Implementation occurred sequentially at 3-month intervals with point-of-care data collected at baseline and every 3 months thereafter for 12 months following roll-out in all communities.Outcome measuresPrimary outcomes were glycated haemoglobin (HbA1c) and systolic blood pressure (SBP), overall and stratified by baseline disease control. We conducted an individual-level analysis using mixed effects regression, adjusting for time, cohort and clustering at the individual and community levels.ResultsAmong patients with diabetes, the CHW-led intervention was associated with a decrease in HbA1c of 0.35%; however, CIs were wide (95% CI −0.90% to 0.20%). In patients with hypertension, there was a 4.7 mm Hg decrease in SBP (95% CI −8.9 to −0.6). In diabetic patients with HbA1c ≥9%, HbA1c decreased by 0.96% (95% CI −1.69% to −0.23%), and in patients with uncontrolled hypertension, SBP decreased by 10.2 mm Hg (95% CI −17.7 to −2.8).ConclusionsWe found that a CHW-led intervention resulted in clinically meaningful improvement in disease markers for patients with diabetes and hypertension, most apparent among patients with hypertension and patients with uncontrolled disease at baseline. These findings suggest that CHWs can play a valuable role in supporting NCD management in LMICs.Trial registration numberNCT02549495.