Slc20a1b is essential for hematopoietic stem/progenitor cell expansion in zebrafish

Science China Life Sciences - Hematopoietic stem and progenitor cells (HSPCs) are able to self-renew and can give rise to all blood lineages throughout their lifetime, yet the mechanisms regulating...     

Transfer RNAs Mediate the Rapid Adaptation of Escherichia coli to Oxidative Stress

Translational systems can respond promptly to sudden environmental changes to provide rapid adaptations to environmental stress. Unlike the well-studied translational responses to oxidative stress in eukaryotic systems, little is known regarding how prokaryotes respond rapidly to oxidative stress in terms of translation. In this study, we measured protein synthesis from the entire Escherichia coli proteome and found that protein synthesis was severely slowed down under oxidative stress. With unchanged translation initiation, this slowdown was caused by decreased translation elongation speed. We further confirmed by tRNA sequencing and qRT-PCR that this deceleration was caused by a global, enzymatic downregulation of almost all tRNA species shortly after exposure to oxidative agents. Elevation in tRNA levels accelerated translation and protected E. coli against oxidative stress caused by hydrogen peroxide and the antibiotic ciprofloxacin. Our results showed that the global regulation of tRNAs mediates the rapid adjustment of the E. coli translation system for prompt adaptation to oxidative stress.     

噬菌体鸡尾酒联合生物有机肥防控番茄青枯病的效果研究

【背景】前期研究表明,可专性侵染青枯菌的噬菌体鸡尾酒(组合)可有效减少番茄青枯病的发生。生物有机肥虽然可降低青枯病发病率,但受田间环境影响,防控效果常不稳定。【目的】为了提高生物有机肥的防控效果,靶向抑制番茄青枯病,探究噬菌体鸡尾酒联合含有解淀粉芽孢杆菌的生物有机肥防控番茄青枯病的田间效果,以及该防控方法对番茄根际细菌群落结构的影响。【方法】将经解淀粉芽孢杆菌T-5二次发酵获得的生物有机肥(Bio-Organic Fertilizer,BOF)在春季作为基肥施入番茄大棚,开花期在番茄根部浇灌噬菌体鸡尾酒悬液,统计青枯病的发生情况和番茄根际青枯菌的数量,根据高通量测序结果分析番茄根际细菌群落的结构变化。【结果】与常规施肥相比,生物有机肥配合噬菌体鸡尾酒(BOF+P)可显著降低番茄青枯病的发病率,显著改变根际细菌群落的β多样性,提高拟杆菌门(Bacteroidetes)的相对丰度,并降低芽单胞菌门(Gemmatimonadetes)的相对丰度。【结论】噬菌体鸡尾酒可显著提升生物有机肥防控番茄青枯病的效果,具有良好的应用潜力。     

Antibiofilm activity of an exopolysaccharide from marine bacterium Vibrio sp. QY101

Bacterial exopolysaccharides have always been suggested to play crucial roles in the bacterial initial adhesion and the development of complex architecture in the later stages of bacterial biofilm formation. However, Escherichia coli group II capsular polysaccharide was characterized to exert broad-spectrum biofilm inhibition activity. In this study, we firstly reported that a bacterial exopolysaccharide (A101) not only inhibits biofilm formation of many bacteria but also disrupts established biofilm of some strains. A101 with an average molecular weight of up to 546 KDa, was isolated and purified from the culture supernatant of the marine bacterium Vibrio sp. QY101 by ethanol precipitation, iron-exchange chromatography and gel filtration chromatography. High performance liquid chromatography traces of the hydrolyzed polysaccharides showed that A101 is primarily consisted of galacturonic acid, glucuronic acid, rhamnose and glucosamine. A101 was demonstrated to inhibit biofilm formation by a wide range of Gram-negative and Gram-positive bacteria without antibacterial activity. Furthermore, A101 displayed a significant disruption on the established biofilm produced by Pseudomonas aeruginosa, but not by Staphylococcus aureus. Importantly, A101 increased the aminoglycosides antibiotics' capability of killing P. aeruginosa biofilm. Cell primary attachment to surfaces and intercellular aggregates assays suggested that A101 inhibited cell aggregates of both P. aeruginosa and S. aureus, while the cell-surface interactions inhibition only occurred in S. aureus, and the pre-formed cell aggregates dispersion induced by A101 only occurred in P. aeruginosa. Taken together, these data identify the antibiofilm activity of A101, which may make it potential in the design of new therapeutic strategies for bacterial biofilm-associated infections and limiting biofilm formation on medical indwelling devices. The found of A101 antibiofilm activity may also promote a new recognition about the functions of bacterial exopolysaccharides.