Noncoding RNA (ncRNA) modulation of gene expression has now been ubiquitously observed across all domains of life. An increasingly apparent role of ncRNAs is to coordinate changes in gene expressions in response to environmental stress. Salmonella enterica, a common food-born pathogen, is known for its striking ability to survive, adapt, and thrive in various unfavourable environments which makes it a particularly difficult pathogen to eliminate as well as an interesting model in which to study ncRNA contributions to cellular stress response. Mounting evidence now suggests that small RNAs (sRNAs) represent key regulators of Salmonella stress adaptation. Approximately 50-500 nucleotides in length, sRNAs regulate gene expression through complementary base pairing with molecular targets and have recently been suggested to outnumber protein-coding genes in bacteria. In this work, we employ small RNA transcriptome sequencing to characterize changes in the sRNA profiles of Salmonella in response to desiccation. In all, we identify 102 previously annotated sRNAs significantly differentially expressed during desiccation; and excitingly, 71 novel sRNAs likewise differentially expressed. Small transcript northern blotting and qRT-PCRs confirm the identities and expressions of several of our novel sRNAs, and computational analyses indicate the majority are highly conserved and structurally related to characterized sRNAs. Predicted sRNA targets include several proteins necessary for desiccation survival and this, in part, suggests a role for desiccation-regulated sRNAs in this stress response. Furthermore, we find individual knockouts of two of the novel sRNAs identified herein, either sRNA1320429 or sRNA3981754, significantly impairs the ability of Salmonella to survive desiccation, confirming their involvements (and suggesting the potential involvements of other sRNAs we identify in this work) in the Salmonella response to desiccation.

Infectious endophthalmitis is a vision-threatening medical emergency that requires prompt clinical diagnosis and the initiation of treatment. However, achieving precision in endophthalmitis management remains challenging. In this review, we provide an updated overview of recent studies that are representative of the current trends in clinical microbiological techniques for infectious endophthalmitis.

An increasingly apparent role of noncoding RNA (ncRNAs) is to coordinate gene expression when bacteria faces various environmental stressors. Salmonella enterica, a well-studied foodborne pathogen, is known for its ability to survive in and adapt to various environmental challenges, making it a difficult pathogen to eliminate, as well as an important model for examining ncRNA contributions to cellular stress survival. A mounting body of evidence implicates small RNAs (sRNAs) as key drivers of Salmonella stress response. Generally thought to be 50-500 nucleotides in length and to occur mainly in intergenic regions, sRNAs regulate protein expression through base pairing with mRNA targets. Through employing a refined definition of sRNAs that allows for shorter sequences and for sRNA loci to overlap with annotated protein-coding gene loci, we have identified 475 previously unannotated sRNAs that are significantly differentially expressed during Carbon starvation (C-starvation). Northern blotting and quantitative RT-PCRs confirm the expressions and identities of several of these novel sRNAs. Additionally, our computational analyses find the majority to be highly conserved and structurally-related to known sRNAs. Importantly, we show that deletion of one of the dynamic sRNAs, sRNA4130247, significantly impairs the Salmonella C-starvation response (CSR), confirming its involvement (and suggesting the involvements of many other sRNAs identified in this work) in the Salmonella CSR. Strikingly, the 475 novel sRNAs identified in this study more than double the number of Salmonella enterica serovar Typhimurium SL1344 sRNAs described to date, increasing the total number of annotated Salmonella sRNAs from 396 to 871. In conclusion, the work presented here provides the first-ever characterization of intragenic sRNAs in Salmonella, experimentally confirms that sRNAs dynamically expressed during the CSR are directly involved in stress survival, and strongly suggests that sRNA loci likely outnumber those of protein-coding genes in Salmonella.