[About the ribosomal biogenesis in human]

Antimicrobial resistance and mechanisms of epigenetic regulation

The rampant use of antibiotics in animal husbandry, farming and clinical disease treatment has led to a significant issue with pathogen resistance worldwide over the past decades. The classical mechanisms of resistance typically investigate antimicrobial resistance resulting from natural resistance, mutation, gene transfer and other processes. However, the emergence and development of bacterial resistance cannot be fully explained from a genetic and biochemical standpoint. Evolution necessitates phenotypic variation, selection, and inheritance. There are indications that epigenetic modifications also play a role in antimicrobial resistance. This review will specifically focus on the effects of DNA modification, histone modification, rRNA methylation and the regulation of non-coding RNAs expression on antimicrobial resistance. In particular, we highlight critical work that how DNA methyltransferases and non-coding RNAs act as transcriptional regulators that allow bacteria to rapidly adapt to environmental changes and control their gene expressions to resist antibiotic stress. Additionally, it will delve into how Nucleolar-associated proteins in bacteria perform histone functions akin to eukaryotes. Epigenetics, a non-classical regulatory mechanism of bacterial resistance, may offer new avenues for antibiotic target selection and the development of novel antibiotics.

Long-term exposure to bisphenol A and its analogues alters the behavior of marine medaka (Oryzias melastigma) and causes hepatic injury

Bisphenols (BPA, BPF, and BPAF) are widely present in the aquatic environment and have various adverse effects on aquatic organisms. However, their hepatic toxicity in marine fish is not fully understood. Hence, we examined the growth parameters, histological features, antioxidant defense mechanisms, and gene expression profiles in the livers of marine medaka after exposure to single and combined bisphenols for 70 days. The final body weight and final body length of males exposed to BPAF were significantly higher than those in the control group, and the survival rate was significantly lower. Bisphenol exposure led to vacuolization and local lesions in the liver, especially in the BPAF group, and altered antioxidant enzyme activity in the liver, leading to oxidative stress. In addition, after bisphenol exposure, marine medaka showed anxiolytic effects and a significant reduction in swimming distance compared with that in the control group. As determined by RNA-seq, bisphenol exposure altered multiple biological pathways in the liver, such as fatty acid biosynthesis, fatty acid metabolism, and ribosome biogenesis pathways, with significant changes in gene expression levels. In particular, chgs and vtgs were significantly up-regulated after BPAF exposure, suggesting an estrogenic effect. Overall, bisphenols can adversely affect the growth and metabolism of marine medaka. BPF and BPAF may not be ideal substitutes for BPA.

Signal Transduction in Ribosome Biogenesis: A Recipe to Avoid Disaster

Energetically speaking, ribosome biogenesis is by far the most costly process of the cell and, therefore, must be highly regulated in order to avoid unnecessary energy expenditure. Not only must ribosomal RNA (rRNA) synthesis, ribosomal protein (RP) transcription, translation, and nuclear import, as well as ribosome assembly, be tightly controlled, these events must be coordinated with other cellular events, such as cell division and differentiation. In addition, ribosome biogenesis must respond rapidly to environmental cues mediated by internal and cell surface receptors, or stress (oxidative stress, DNA damage, amino acid depletion, etc.). This review examines some of the well-studied pathways known to control ribosome biogenesis (PI3K-AKT-mTOR, RB-p53, MYC) and how they may interact with some of the less well studied pathways (eIF2α kinase and RNA editing/splicing) in higher eukaryotes to regulate ribosome biogenesis, assembly, and protein translation in a dynamic manner.