Intracellular pH (pH i ) is a fundamental indicator of cellular physiological state, regulating cellular state and function, and has important research values. Although various probes for measuring intracellular pH were available, it is challenging to reflect pH i in real-time and reversible manners. Herein, we developed a whole-cell bioluminescent (BL) probe based on wild type BL bacteria, photobacterium phosphoreum ( P. phosphoreum ), to determine and image pH i . The dependence of BL intensity of P. phosphoreum on pH values of culture solutions was established. It was found that BL intensity could respond to the change of pH values rapidly and reversibly. We further revealed that P. phosphoreum maintained pH homeostasis in the extracellular pH (pH e ) within the range of 5.0–7.0, while intracellular pH homeostasis was destroyed at the alkaline pH e . This method opens up the enormous potential of BL bacteria as an alternative to fluorescence for monitoring and imaging pH i .
Dao-Lai Zhang,Yu-Jing Sun,Ming-Liang Ma,Yi-jing Wang,Hui Lin,Rui-Rui Li,Zong-Lai Liang,Yuan Gao,Zhao Yang,Dong-Fang He,Amy Lin,Hui Mo,Yu-Jing Lu,Meng-Jing Li,Wei Kong,Ka Young Chung,Fan Yi,Jian-Yuan Li,Ying-Ying Qin,Jingxin Li,Alex R B Thomsen,Alem W Kahsai,Zi-Jiang Chen,Zhi-Gang Xu,Mingyao Liu,Dali Li,Xiao Yu,Jin-Peng Sun
Luminal fluid reabsorption plays a fundamental role in male fertility. We demonstrated that the ubiquitous GPCR signaling proteins Gq and β-arrestin-1 are essential for fluid reabsorption because they mediate coupling between an orphan receptor ADGRG2 (GPR64) and the ion channel CFTR. A reduction in protein level or deficiency of ADGRG2, Gq or β-arrestin-1 in a mouse model led to an imbalance in pH homeostasis in the efferent ductules due to decreased constitutive CFTR currents. Efferent ductule dysfunction was rescued by the specific activation of another GPCR, AGTR2. Further mechanistic analysis revealed that β-arrestin-1 acts as a scaffold for ADGRG2/CFTR complex formation in apical membranes, whereas specific residues of ADGRG2 confer coupling specificity for different G protein subtypes, this specificity is critical for male fertility. Therefore, manipulation of the signaling components of the ADGRG2-Gq/β-arrestin-1/CFTR complex by small molecules may be an effective therapeutic strategy for male infertility.
Microbial-based iron reduction is an emerging technology used as an alternative to conventional chemical-based iron reduction. The iron reduction in kaolin refinement is vital for enhancing its commercial value. Extensive studies on microbial-based iron reduction mainly focus on Gram-negative bacteria, whereas little is understood about Gram-positive bacteria’s mechanism and potential application. This study aims to investigate the iron-reducing mechanism of two Gram-positive bacterial isolates, Bacillus cereus (B. cereus) and Staphylococcus aureus (S. aureus). By varying the growth environment of bacteria and monitoring the biochemical changes during the process of iron reduction, the results show that Gram-positive bacterial iron reduction performance depends on the medium composition, differing from Gram-negative bacteria-based reduction processes. Nitrogen-rich medium facilitates the microbial basification of the medium, where the alkaline conditions impact the microbial iron reduction process by altering the gene expression involved in intracellular pH homeostasis and microbial growth. This discovery will contribute to the mineral refining processes and promote the development of microbial-based bioprocesses for ore purification, while also laying the foundation for investigating other Gram-positive bacterial iron-reducing ability.
危险品化学品经营许可证（带存储）