Analysis of the Oxidative Stress Regulon Identifies soxS as a Genetic Target for Resistance Reversal in Multidrug-Resistant Klebsiella pneumoniae

In bacteria, the defense system deployed to counter oxidative stress is orchestrated by three transcriptional factors, SoxS, SoxR, and OxyR. Although the regulon that these factors control is known in many bacteria, similar data are not available for Klebsiella pneumoniae. To address this data gap, oxidative stress was artificially induced in K. pneumoniae MGH78578 using paraquat and the corresponding oxidative stress regulon recorded using transcriptome sequencing (RNA-seq). The soxS gene was significantly induced during oxidative stress, and a knockout mutant was constructed to explore its functionality. The wild type and mutant were grown in the presence of paraquat and subjected to RNA-seq to elucidate the soxS regulon in K. pneumoniae MGH78578. Genes that are commonly regulated both in the oxidative stress and soxS regulons were identified and denoted as the oxidative SoxS regulon; these included a group of genes specifically regulated by SoxS. Efflux pump-encoding genes and global regulators were identified as part of this regulon. Consequently, the isogenic soxS mutant was found to exhibit a reduction in the minimum bactericidal concentration against tetracycline compared to that of the wild type. Impaired efflux activity, allowing tetracycline to be accumulated in the cytoplasm to bactericidal levels, was further evaluated using a tetraphenylphosphonium (TPP+) accumulation assay. The soxS mutant was also susceptible to tetracycline in vivo in a zebrafish embryo model. We conclude that the soxS gene could be considered a genetic target against which an inhibitor could be developed and used in combinatorial therapy to combat infections associated with multidrug-resistant K. pneumoniae. IMPORTANCE Antimicrobial resistance is a global health challenge. Few new antibiotics have been developed for use over the years, and preserving the efficacy of existing compounds is an important step to protect public health. This paper describes a study that examines the effects of exogenously induced oxidative stress on K. pneumoniae and uncovers a target that could be useful to harness as a strategy to mitigate resistance

Distinct Steps of Neural Induction Revealed by Asterix, Obelix and TrkC, Genes Induced by Different Signals from the Organizer

The amniote organizer (Hensen's node) can induce a complete nervous system when grafted into a peripheral region of a host embryo. Although BMP inhibition has been implicated in neural induction, non-neural cells cannot respond to BMP antagonists unless previously exposed to a node graft for at least 5 hours before BMP inhibitors. To define signals and responses during the first 5 hours of node signals, a differential screen was conducted. Here we describe three early response genes: two of them, Asterix and Obelix, encode previously undescribed proteins of unknown function but Obelix appears to be a nuclear RNA-binding protein. The third is TrkC, a neurotrophin receptor. All three genes are induced by a node graft within 4–5 hours but they differ in the extent to which they are inducible by FGF: FGF is both necessary and sufficient to induce Asterix, sufficient but not necessary to induce Obelix and neither sufficient nor necessary for induction of TrkC. These genes are also not induced by retinoic acid, Noggin, Chordin, Dkk1, Cerberus, HGF/SF, Somatostatin or ionomycin-mediated Calcium entry. Comparison of the expression and regulation of these genes with other early neural markers reveals three distinct “epochs”, or temporal waves, of gene expression accompanying neural induction by a grafted organizer, which are mirrored by specific stages of normal neural plate development. The results are consistent with neural induction being a cascade of responses elicited by different signals, culminating in the formation of a patterned nervous system

Analysis of the Oxidative Stress Regulon Identifies soxS as a Genetic Target for Resistance Reversal in Multidrug-Resistant Klebsiella pneumoniae

Article no. e00867-21In bacteria, the defense system deployed to counter oxidative stress is orchestrated by three transcriptional factors, SoxS, SoxR, and OxyR. Although the regulon that these factors control is known in many bacteria, similar data are not available for Klebsiella pneumoniae. To address this data gap, oxidative stress was artificially induced in K. pneumoniae MGH78578 using paraquat and the corresponding oxidative stress regulon recorded using transcriptome sequencing (RNA-seq). The soxS gene was significantly induced during oxidative stress, and a knockout mutant was constructed to explore its functionality. The wild type and mutant were grown in the presence of paraquat and subjected to RNA-seq to elucidate the soxS regulon in K. pneumoniae MGH78578. Genes that are commonly regulated both in the oxidative stress and soxS regulons were identified and denoted as the oxidative SoxS regulon; these included a group of genes specifically regulated by SoxS. Efflux pump-encoding genes and global regulators were identified as part of this regulon. Consequently, the isogenic soxS mutant was found to exhibit a reduction in the minimum bactericidal concentration against tetracycline compared to that of the wild type. Impaired efflux activity, allowing tetracycline to be accumulated in the cytoplasm to bactericidal levels, was further evaluated using a tetraphenylphosphonium (TPP1) accumulation assay. The soxS mutant was also susceptible to tetracycline in vivo in a zebrafish embryo model. We conclude that the soxS gene could be considered a genetic target against which an inhibitor could be developed and used in combinatorial therapy to combat infections associated with multidrug-resistant K. pneumoniaeBiochemijos katedraVytauto Didžiojo universiteta

Alterations in the Transcriptional Landscape Allow Differential Desiccation Tolerance in Clinical Cronobacter sakazakii

Cronobacter sakazakii is a typical example of a xerotolerant bacterium. It is epidemiologically linked to low-moisture foods like powdered infant formula (PIF) and is associated with high fatality rates among neonates. We characterized the xerotolerance in a clinically isolated strain, Cronobacter sakazakii ATCC™29544T, and compared the desiccation tolerance with that of an environmental strain, C. sakazakii SP291, whose desiccation tolerance was previously characterized. We found that, although the clinical strain was desiccation-tolerant, the level of tolerance was compromised when compared with that of the environmental strain. Transcriptome sequencing (RNA-seq)-based deep transcriptomic characterization identified a unique transcriptional profile in the clinical strain compared with what was already known for the environmental strain. As RNA-seq was also carried out under different TSB growth conditions, genes that were expressed specifically under desiccated conditions were identified and denoted as desiccation responsive genes (DRGs). Interestingly, these DRGs included transcriptomic factors like fnr, ramA, and genes associated with inositol metabolism, a phenotype as yet unreported in C. sakazakii. Further, the clinical strain did not express the proP gene, which was previously reported to be very important for desiccation survival and persistence. Interestingly, analysis of the plasmid genes showed that the iron metabolism in desiccated C. sakazakii ATCC™29544T cells specifically involved the siderophore cronobactin, encoded by the iucABCD genes. Confirmatory studies using quantitative reverse transcription-PCR (qRT-PCR) determined that, though the secondary desiccation response genes were upregulated in C. sakazakii ATCC™29544T, the level of upregulation was lower than that in C. sakazakii SP291. All these factors may collectively contribute to the compromised desiccation tolerance in the clinical strain

Breve dizionario di psicopatologia dello sviluppo

IntroductionConventional Zâ scores are generated by subtracting the mean and dividing by the standard deviation. More recent methods linearly correct for age, sex, and education, so that these â adjustedâ Zâ scores better represent whether an individual’s cognitive performance is abnormal. Extreme negative Zâ scores for individuals relative to this normative distribution are considered indicative of cognitive deficiency.MethodsIn this article, we consider nonlinear shape constrained additive models accounting for age, sex, and education (correcting for nonlinearity). Additional shape constrained additive models account for varying standard deviation of the cognitive scores with age (correcting for heterogeneity of variance).ResultsCorrected Zâ scores based on nonlinear shape constrained additive models provide improved adjustment for age, sex, and education, as indicated by higher adjustedâ R2.DiscussionNonlinearly corrected Zâ scores with respect to age, sex, and education with ageâ varying residual standard deviation allow for improved detection of nonâ normative extreme cognitive scores.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152598/1/dad2jdadm201908003.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152598/2/dad2jdadm201908003-sup-0001.pd

Clinical and volumetric changes with increasing functional impairment in familial frontotemporal lobar degeneration.

IntroductionThe Advancing Research and Treatment in Frontotemporal Lobar Degeneration and Longitudinal Evaluation of Familial Frontotemporal Dementia Subjects longitudinal studies were designed to describe the natural history of familial-frontotemporal lobar degeneration due to autosomal dominant mutations.MethodsWe examined cognitive performance, behavioral ratings, and brain volumes from the first time point in 320 MAPT, GRN, and C9orf72 family members, including 102 non-mutation carriers, 103 asymptomatic carriers, 43 mildly/questionably symptomatic carriers, and 72 carriers with dementia.ResultsAsymptomatic carriers showed similar scores on all clinical measures compared with noncarriers but reduced frontal and temporal volumes. Those with mild/questionable impairment showed decreased verbal recall, fluency, and Trail Making Test performance and impaired mood and self-monitoring. Dementia was associated with impairment in all measures. All MAPT carriers with dementia showed temporal atrophy, but otherwise, there was no single cognitive test or brain region that was abnormal in all subjects.DiscussionImaging changes appear to precede clinical changes in familial-frontotemporal lobar degeneration, but specific early clinical and imaging changes vary across individuals