The ssgA gene of Streptomyces griseus B2682, when present in high copy number, results in both suppression of sporulation and fragmented growth of mycelia. Western analysis with polyclonal antibodies against the gene product (SsgA) revealed a close correlation between SsgA accumulation and the onset of sporulation in wild-type cells. The protein was only detected in the cytoplasm. Certain developmental mutants of S. griseus (afs, relC and brgA) which are defective in aerial mycelium formation in solid culture and submerged spore formation in liquid culture failed to accumulate SsgA. The SsgA protein appeared shortly (1 h) after nutritional shift-down of strain B2682 cells, afs mutant cells sporulated and expressed SsgA only when A-factor was present both before and after nutritional shift-down. Introduction of the ssgA gene in a low-copy-number vector into strain B2682 resulted in fivefold overexpression of SsgA, and was accompanied by fragmented growth of mycelia and suppression of submerged spore formation (in liquid culture) and aerial mycelium formation (in solid culture). Streptomycin production was not inhibited. In a control experiment, a nonfunctional ssgA gene possessing a frameshift mutation near its N-terminus had no effect on either growth or sporulation. It is proposed that the ssgA gene product plays a role in promoting the developmental process of S. griseus.

A RelC deletion mutant, KO-100, of Streptomyces coelicolor A3(2) has been isolated from a collection of spontaneous thiostrepton-resistant mutants.

No abstract

Stress-induced adaptations require multiple levels of regulation in all organisms to repair cellular damage. In the present study we evaluated the genome-wide transcriptional and translational changes following heat stress exposure in the soil-dwelling model actinomycete bacterium, Streptomyces coelicolor. The combined analysis revealed an unprecedented level of translational control of gene expression, deduced through polysome profiling, in addition to transcriptional changes. Our data show little correlation between the transcriptome and 'translatome'; while an obvious downward trend in genome wide transcription was observed, polysome associated transcripts following heat-shock showed an opposite upward trend. A handful of key protein players, including the major molecular chaperones and proteases were highly induced at both the transcriptional and translational level following heat-shock, a phenomenon known as 'potentiation'. Many other transcripts encoding cold-shock proteins, ABC-transporter systems, multiple transcription factors were more highly polysomeassociated following heat stress; interestingly, these protein families were not induced at the transcriptional level and therefore were not previously identified as part of the stress response. Thus, stress coping mechanisms at the level of gene expression in this bacterium go well beyond the induction of a relatively small number of molecular chaperones and proteases in order to ensure cellular survival at non-physiological temperatures.

For the first time we report the relative influences of vitamin D2 and vitamin D3 on genome-wide gene expression in whole blood from healthy women, representing two ethnic groups, white European and South Asian. In this randomised placebo-controlled trial, participants were given daily physiological doses (15 µg) of either vitamin D2 or D3 for 12 weeks and changes in the transcriptome were compared relative to the transcriptome at baseline. While there was some overlap in the repertoire of differentially expressed genes after supplementation with each vitamin D source, most changes were specific to either vitamin D3 or vitamin D2, suggesting that each form of the vitamin may have different effects on human physiology. Notably, following vitamin D3 supplementation, the majority of changes in gene expression reflected a down-regulation in the activity of genes, many encoding components of the innate and adaptive immune systems. These are consistent with the emerging concept that vitamin D orchestrates a shift in the immune system towards a more tolerogenic status. Moreover, gene expression associated with type 1 and type 2 interferon activity differed following supplementation with either vitamin D2 or vitamin D3, with only vitamin D3 having a stimulatory effect. Interferons play a critical role in the innate response to infection and aberrant type 1 interferon signalling has recently been implicated in severe Covid-19 disease. The observed differences in gene expression after supplementation with vitamin D2 compared with vitamin D3 warrant a more intensive investigation of the biological effects of the two forms of vitamin D on human physiology.

Cataract surgery removes the diseased lens of the eye replacing it with an intraocular lens (IOL), restoring visual acuity. However, accommodation, the lens’ ability to provide dynamic change in focus, is lost. A number of accommodative intraocular lens (AIOL) designs have been considered although none have provided a truly effective clinical AIOL. Two-dimensional titanium carbide (Ti3C2T x ) MXene has been used as a transparent conductive electrode within an AIOL feasibility study. Nevertheless, the potential for Ti3C2T x to repress excessive inflammation and promote wound healing following cataract surgery has not been considered. Cataract surgery can trigger chronic inflammation and epithelial-mesenchymal transition (EMT) in residual lens epithelial cells (LECs), producing a fibrotic mass across the optic known as posterior capsule opacification (PCO). With a large surface area and capacity for surface functionalisation, MXene has properties enabling a dual purpose AIOL design with an additional therapeutic role in the repression of pathways leading to PCO development. In this study, Ti3C2T x MXene was investigated to determine its impact on pathways leading to chronic inflammation and EMT using an in vitro LECs model. Ti3C2T x MXene was synthesised and characterised using UV-vis spectroscopy, dynamic light scattering and scanning electron microscopy. Changes in markers linked to inflammation and EMT in Ti3C2T x -treated LECs were measured using enzyme linked immunosorbent assays, quantitative polymerase chain reaction, scratch assay, RNA sequencing for whole-cell gene expression profiling and lipidomics analysis. Ti3C2T x significantly reduced the expression of pro-inflammatory cytokines by IL-1β primed LECs and did not advocate EMT through promoting a positive resolution of the wound healing response. This study supports the role of Ti3C2T x within an AIOL design with the potential to repress key developmental pathways leading to PCO.

RNA-seq has matured and become an important tool for studying RNA biology. Here we compared two RNA-seq (Illumina sequencing by synthesis and MGI DNBSEQ™) and two microarray platforms (Illumina Expression BeadChip and GeneChip™ Human Transcriptome Array 2.0) in healthy individuals administered recombinant human erythropoietin for transcriptome-wide quantification of differential gene expression. The results show that total RNA sequencing combined with DNB-seq produced a multitude of genes of biological relevance and significance in response to recombinant human erythropoietin, in contrast to other platforms. Through data triangulation linking genes to functions, genes representing the processes of erythropoiesis as well as non-erythropoietic functions of erythropoietin were unveiled. This study provides a knowledge base of genes characterising the responses to recombinant human erythropoietin through cross-platform comparison and validation.

AbstractVitamin D deficiency increases the risk of developing multiple sclerosis (MS) but there is uncertainty about what dose and form of vitamin D could improve the clinical course of MS. The mechanisms underlying the effects of vitamin D in MS are not clear. Vitamin D3 increases the rate of differentiation of primary oligodendrocyte precursor cells (OPCs), suggesting that it might help remyelination in addition to modulating the immune response. Here we analyzed the transcriptome of differentiating rat CG4 OPCs treated with vitamin D2 or with D3 at 24 h and 72 h following onset of differentiation. Differentiation alone changed the expression of about 10% of the genes at 72 h compared to 24 h. Vitamin D2 and D3 exerted different effects on gene expression, with D3 influencing 1,272 genes and D2 574 at 24 h. The expression of the vast majority of these genes was either not changed in differentiating cells not exposed to vitamin D or followed the same trajectory as the latter. D3-repressed genes were enriched for gene ontology categories including transcription factors and the Notch pathway, while D3-induced genes were enriched for the Ras pathway. These findings should help to identify mechanisms mediating D3 action in MS.