Biology subjects

Barbosa, H.

Publications and source records attributed to Barbosa, H..

4 recordsLinked to original sources

bioRxiv2023

Comparative proteomic analysis of the hemolymph and salivary glands of Rhodnius prolixus and R. colombiensis reveals candidates associated with differential lytic activity against Trypanosoma cruzi I and T. cruzi II

BackgroundImmune response of triatomines plays an important role in the success or failure of transmission of T. cruzi. Studies on parasite-vector interaction have shown the presence of trypanolytic factors and have been observed to be differentially expressed among triatomines, which affects the transmission of some T. cruzi strains or DTUs (Discrete Typing Units). Methodology/Principal FindingsTrypanolytic factors were detected in the hemolymph and saliva of R. prolixus against epimastigotes and trypomastigotes of T. cruzi II. To identify the components of the immune response that could be involved in this lytic activity, a comparative proteomic analysis was carried out, detecting 120 proteins in the hemolymph of R. prolixus and 107 in R. colombiensis. In salivary glands, 1103 proteins were detected in R. prolixus and 853 in R. colombiensis. A higher relative abundance of lysozyme, prolixin, nitrophorins, and serpin as immune response proteins was detected in the hemolymph of R. prolixus. Among the R. prolixus salivary proteins, a higher relative abundance of nitrophorins, lipocalins, and triabins was detected. The higher relative abundance of these immune factors in R. prolixus supports their participation in the lytic activity on T. cruzi II, but not on T. cruzi I, which is resistant to lysis by hemolymph and salivary proteins of R. prolixus due to mechanisms of evading oxidative stress caused by immune factors. Conclusions/SignificanceT. cruzi I is a DTU distributed from the southern United States to the center of Chile and Argentina, and its successful spread across this range could be related to resistance to oxidative stress in vectors. Future proteomic and transcriptomic studies on vectors and the interactions of the intestinal microbiota with parasites will help to confirm the determinants of successful or failed vector transmission of T. cruzi DTUs in different parts of the Western Hemisphere. Author summarySome factors can facilitate or prevent T. cruzi transmission, i.e. vector immunity. Our work has managed to detect a stronger immune response against T. cruzi II in R. prolixus saliva and haemolymph, compared to that of R. colombiensis. Proteins from both species saliva and haemolymph were analysed for studying factors which might have been involved in such response; most proteins were detected in both species haemolymph, thereby indicating common immune mechanisms. Three proteins having oxidative immune activity were only expressed in R. prolixus. Lipocalin diversity and abundance predominated in R. prolixus saliva; these proteins are involved in nitric oxide metabolism and their role in immunity could be key in host defence against T. cruzi. Recognising the components modulating parasite transmission in a vector helps in understanding how such factors act independently and how they would act synergistically against T. cruzi, thereby enabling us to establish tools regarding Chagas disease epidemiology, aimed at predicting T. cruzi distribution and creating transmission control mechanisms.

microbiology↗

bioRxiv2018

Inpatient mobility to predict hospital-onset Clostridium difficile: a network approach

With hospital-onset Clostridium difficile Infection (CDI) still a common occurrence in the U.S., this paper examines the relationship between unit-wide CDI susceptibility and inpatient mobility and creates a predictive measure of CDI called \"Contagion Centrality\". A mobility network was constructed using two years of patient electronic health record (EHR) data within a 739-bed hospital (Jan. 2013 - Dec. 2014; n=72,636 admissions). Network centrality measures were calculated for each hospital unit (node) providing clinical context for each in terms of patient transfers between units (edges). Daily unit-wide CDI susceptibility scores were calculated using logistic regression and compared to network centrality measures to determine the relationship between unit CDI susceptibility and patient mobility. Closeness centrality was a statistically significant measure associated with unit susceptibility (p-value < 0.05), highlighting the importance of incoming patient mobility in CDI prevention at the unit-level. Contagion Centrality (CC) was calculated using incoming inpatient transfer rates, unit-wide susceptibility of CDI, and current hospital CDI infections. This measure is statistically significant (p-value <0.05) with our outcome of hospital-onset CDI cases, and captures the additional opportunities for transmission associated with inpatient transfers. We have used this analysis to create an easily interpretable and informative clinical tool showing this relationship and risk of hospital-onset CDI in real-time. Quantifying and visualizing the combination of inpatient transfers, unit-wide risk, and current infections help identify hospital units at risk of developing a CDI outbreak, and thus provide clinicians and infection prevention staff with advanced warning and specific location data to concentrate prevention efforts.

epidemiology↗

bioRxiv2018

Precise tuning of gene expression output levels in mammalian cells

Precise, analogue regulation of gene expression is critical for development, homeostasis and regeneration in mammals. In contrast, widely employed experimental and therapeutic approaches such as knock-in/out strategies are more suitable for binary control of gene activity, while RNA interference (RNAi) can lead to pervasive off-target effects and unpredictable levels of repression. Here we report on a method for the precise control of gene expression levels in mammalian cells based on engineered, synthetic microRNA response elements (MREs). To develop this system, we established a high-throughput sequencing approach for measuring the efficacy of thousands of miR-17 MRE variants. This allowed us to create a library of microRNA silencing-mediated fine-tuners (miSFITs) of varying strength that can be employed to control the expression of user specified genes. To demonstrate the value of this technology, we used a panel of miSFITs to tune the expression of a peptide antigen in a mouse melanoma model. This analysis revealed that antigen expression level is a key determinant of the anti-tumour immune response in vitro and in vivo. miSFITs are a powerful tool for modulating gene expression output levels with applications in research and cellular engineering.

synthetic biology↗

bioRxiv2018

Decoupling tRNA promoter and processing activities enables specific Pol-II Cas9 guide RNA expression

Spatial/temporal control of Cas9 guide RNA expression could considerably expand the utility of CRISPR-based technologies. Current approaches based on tRNA processing offer a promising strategy but suffer from high background. Here we developed a variant screening platform to identify differential sequence determinants of human tRNA promoter and processing activities. Rational design based on the ensuing principles allowed us to engineer an improved tRNA scaffold that enabled highly specific guide RNA production from a Pol-II promoter.

bioengineering↗