COL R Acinetobacter baumannii sRNA Signatures : Computational Comparative Identification and Biological Targets

Multidrug-Resistant (MDR) and Extensively Drug Resistant (XDR) Acinetobacter baumannii (Ab) represent a serious cause of healthcare-associated infections worldwide. Currently, the available treatment options are very restricted and colistin-based therapies are last-line treatments of these infections, even though colistin resistant (COL R) Ab have rarely been isolated yet. In bacteria, small non-coding RNAs (sRNAs) have been implicated in regulatory pathways of different biological functions, however, no knowledge exists about the sRNA role on the biological adaptation in COL R Ab. Our study investigated two Italian XDR isogenic colistin-susceptible/resistant (COL S/R) Ab strain-pairs to discover new sRNA signatures. Comparative sRNA transcriptome (sRNAome) analyses were carried out by Illumina RNA-seq using both a Tru-Seq and a Short Insert library, whilst Ab ATCC 17978 and ACICU Reference Genome assembly, mapping, annotation and statistically significant differential expression (q -value ≤ 0.01) of the raw reads were performed by the Rockhopper tool. A computational filtering, sorting only similarly statistically significant differentially expressed (DE) sRNAs mapping on the same gene in both COL R Ab isolates was conducted. COL R vs. COL S sRNAome, analyzed integrating the DE sRNAs obtained from the two different libraries, revealed some statistically significant DE sRNAs in COL R Ab. In detail, we found: (i) two different under-expressed cis -acting sRNAs (Ab sRNA and Ab sRNA) mapping in antisense orientation the 16S rRNA gene A1S_r01, (ii) one under-expressed cis -acting sRNA (Ab sRNA) targeting the A1S_2505 gene (hypothetical protein), (iii) one under-expressed microRNA-size small RNA fragment (Ab sRNA) and its pre-micro Ab sRNA targeting the A1S_0501 gene (hypothetical protein), (iv) as well as an over-expressed microRNA-size small RNA fragment (Ab sRNA) and its pre-micro Ab sRNA targeting the A1S_3097 gene (signal peptide). Custom TaqMan ® probe-based real-time qPCRs validated the expression pattern of the selected sRNA candidates shown by RNA-seq. Furthermore, analysis on sRNA ΔA1S_r01, ΔA1S_2505 as well as the over-expressed A1S_3097 mutants revealed no effects on colistin resistance. Our study, for the first time, found the sRNAome signatures of clinical COL R Ab with a computational prediction of their targets related to protein synthesis, host-microbe interaction and other different biological functions, including biofilm production, cell-cycle control, virulence, and antibiotic-resistance

Colistin Resistance Onset Strategies and Genomic Mosaicism in Clinical Acinetobacter baumannii Lineages

Abstract: The treatment of multidrug-resistant Gram-negative infections is based on colistin. As result, COL-resistance (COL-R) can develop and spread. In Acinetobacter baumannii, a crucial step is to understand COL-R onset and stability, still far to be elucidated. COL-R phenotypic stability, onset modalities, and phylogenomics were investigated in a clinical A. baumannii sample showing a COL resistant (COLR) phenotype at first isolation. COL-R was confirmed by Minimum-InhibitoryConcentrations as well as investigated by Resistance-Induction assays and Population-AnalysisProfiles (PAPs) to determine: (i) stability; (ii) inducibility; (iii) heteroresistance. Genomics was performed by Mi-Seq Whole-Genome-Sequencing, Phylogenesis, and Genomic Epidemiology by bioinformatics. COLR A. baumannii were subdivided as follows: (i) 3 A. baumannii with stable and high COL MICs defining the “homogeneous-resistant” onset phenotype; (ii) 6 A. baumannii with variable and lower COL MICs displaying a “COL-inducible” onset phenotype responsible for adaptive-resistance or a “subpopulation” onset phenotype responsible for COL-heteroresistance. COL-R stability and onset strategies were not uniquely linked to the amount of LPS and cell envelope charge. Phylogenomics categorized 3 lineages clustering stable and/or unstable COL-R phenotypes with increasing genomic complexity. Likewise, different nsSNP profiling in genes already associated with COL-R marked the stable and/or unstable COL-R phenotypes. Our investigation finds out that A. baumannii can range through unstable or stable COLR phenotypes emerging via different “onset strategies” within phylogenetic lineages displaying increasing genomic mosaicism

Enhancing grain size in durum wheat using RNAi to knockdown GW2 genes

Sestili F., Pagliarello R., Zega A., Saletti R., Pucci A., Botticella E., Masci S., Tundo S., Moscetti I., Foti S., Lafiandra D. 2019 Enhancing grain size in durum wheat using RNAi to knock-down GW2 genes. Theoretical and Applied Genetics, 132(2): 419-429 https://doi.org/10.1007/s00122-018-3229-9. Abstract Key message Knocking down GW2 enhances grain size by regulating genes encoding the synthesis of cytokinin, gibberellin, starch and cell wall. Abstract Raising crop yield is a priority task in the light of the continuing growth of the world’s population and the inexorable loss of arable land to urbanization. Here, the RNAi approach was taken to reduce the abundance of Grain Weight 2 (GW2) transcript in the durum wheat cultivar Svevo. The effect of the knockdown was to increase the grains’ starch content by 10–40%, their width by 4–13% and their surface area by 3–5%. Transcriptomic profiling, based on a quantitative real-time PCR platform, revealed that the transcript abundance of genes encoding both cytokinin dehydrogenase 1 and the large subunit of ADP-glucose pyrophosphorylase was markedly increased in the transgenic lines, whereas that of the genes encoding cytokinin dehydrogenase 2 and gibberellin 3-oxidase was reduced. A proteomic analysis of the non-storage fraction extracted from mature grains detected that eleven proteins were differentially represented in the transgenic compared to wild-type grain: some of these were involved, or at least potentially involved, in cell wall development, suggesting a role of GW2 in the regulation of cell division in the wheat grain

Nutritional status and quality of life in adults undergoing allogeneic hematopoietic stem cell transplantation

Although the effects of malnutrition on morbidity and mortality in adult patients undergoing allogeneic hematopoietic stem cell transplantation are clear, the relationship with quality of life (QOL) is less clear. The purpose of this study was to assess the relationship between malnutrition and QOL. A prospective observational study was conducted in 36 adult patients undergoing allogeneic hematopoietic stem cell transplantation. Adapted criteria of the Global Leadership Initiative on malnutrition have been used for the diagnosis of malnutrition in clinical settings. A cancer linear analog scale was used to assess QOL. Overall QOL at 14 days after allogeneic hematopoietic stem cell transplantation was 37.1 (95% CI 2.9–45.39) in patients without severe malnutrition, versus 16.0 (95% CI − 6.6 to 38.6) in patients with severe malnutrition (p = 0.05). At discharge, it was 48.0 (95% CI 38.4–57.6) versus 34.0 (95% CI 4.1–63.9) (p = 0.27). The results of our study suggest that patients with severe malnutrition at discharge tend to have worse QOL. A larger cohort of patients is required to confirm this hypothesis

Balancing the Virulence and Antimicrobial Resistance in VISA DAP-R CA-MRSA Superbug

Background: Methicillin-resistant Staphylococcus aureus (MRSA) with intermediate resistance to Vancomycin (VISA) is reported worldwide. These strains frequently emerge among hospital-associated (HA)-MRSA and rarely within community-acquired (CA)-MRSA. Here, the genomic and transcriptomic adaptations distinguishing VISA daptomycin resistant (DAP-R) CA-MRSA, which emerged in a hospitalized patient under glycopeptide treatment, were explored. Methods: Whole-genome sequencing, RNA-Seq and bioinformatics were carried out. Results: Our CA-MRSA clustered in the USA400 lineage showing additional antimicrobial resistance (AMR) versus DAP and glycopeptides. Resistomics revealed adaptations related to glycopeptide, daptomycin and rifampin resistance (mprF nsSNPS and overexpression of glycopeptide and daptomycin-resistance related genes). Similar changes were detected in virulence traits (agrA HI-nsSNPs and toxin gene underexpression), in which a decrease was observed despite the abundance of virulence-related genes. Our results predicted a balance in adaptations, decreasing the virulence and biological costs to support the co-occurrence of extensive AMR in a hypervirulent genomic background. Conclusion: Our data show that VISA DAP-R CA-MRSA shifts the potential hypervirulent behavior of CA-MRSA towards the acquisition and maintenance of extensive AMR, by a decrease in virulence and biological costs mediated by a “compensatory modulatory mutation” silencing the Agr quorum-sensing cascade