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One of the fundamental techniques in genetic engineering is the creation of Escherichia coli competent cells using the CaCl2 method. However, little is known about the mechanism of E. coli competence formation. We have previously found that the cspA gene may play an indispensable role in the preparation of E. coli DH5α competent cells through multiomics analysis. In the present study, the cellular localization, physicochemical properties, and function of the protein expressed by the cspA gene were analyzed. To investigate the role of the cspA gene in E. coli transformation, cspA‐deficient mutant was constructed by red homologous recombination. The growth, transformation efficiency, and cell morphology of the cspA‐deficient strain and E. coli were compared. It was found that there were no noticeable differences in growth and morphology between E. coli and the cspA‐deficient strain cultured at 37°C, but the mutant exhibited increased transformation efficiencies compared to E. coli DH5α for plasmids pUC19, pET‐32a, and p1304, with enhancements of 2.23, 2.24, and 3.46 times, respectively. It was proved that cspA gene is an important negative regulatory gene in the CaCl2 preparation of competent cells. [ABSTRACT FROM AUTHOR]

Circadian disruption such as shift work, jet lag, has gradually become a global health issue and is closely associated with various metabolic disorders. The influence and mechanism of circadian disruption on renal injury in chronic kidney disease (CKD) remains inadequately understood. Here, we evaluated the impact of environmental light disruption on the progression of chronic renal injury in CKD mice. By using two abnormal light exposure models to induce circadian disruption, we found that circadian disruption induced by weekly light/dark cycle reversal (LDDL) significantly exacerbated renal dysfunction, accelerated renal injury, and promoted renal fibrosis in mice with 5/6 nephrectomy and unilateral ureteral obstruction (UUO). Mechanistically, RNA‐seq analysis revealed significant immune and metabolic disorder in the LDDL‐conditioned CKD kidneys. Consistently, renal content of ATP was decreased and ROS production was increased in the kidney tissues of the LDDL‐challenged CKD mice. Untargeted metabolomics revealed a significant buildup of lipids in the kidney affected by LDDL. Notably, the level of β‐NMN, a crucial intermediate in the NAD+ pathway, was found to be particularly reduced. Moreover, we demonstrated that both β‐NMN and melatonin administration could significantly rescue the light‐disruption associated kidney dysfunction. In conclusion, environmental circadian disruption may exacerbate chronic kidney injury by facilitating inflammatory responses and disturbing metabolic homeostasis. β‐NMN and melatonin treatments may hold potential as promising approaches for preventing and treating light‐disruption associated CKD. [ABSTRACT FROM AUTHOR]

One of the commonly employed methods in molecular biology is to utilize calcium chloride to treat Escherichia coli for the preparation of competent cells to facilitate foreign gene expression. However, the molecular mechanisms underlying Ca2+ mediation of competent cell formation and identification of the key genes involved in the process remain unclear. In previous studies, the combined analysis of transcriptomics and proteomics revealed bhsA as one of the crucial genes. The gene ontology functional annotation of bhsA identified it as a member of the YhcN family encoding an outer membrane protein that confers resistance to various stresses. The IPR0108542 domain found within the protein plays a significant role in stress response and biofilm formation in E. coli. Analysis of the STRING database showed that the proteins interacting with bhsA are primarily involved in biofilm formation and stress resistance. Using the RED homologous recombination method, a bhsA deletion strain was constructed to verify its role in E. coli genetic transformation. Although the mutant strain showed no significant differences in morphology or growth trend when compared to the wild‐type strain, its transformation efficiency decreased by 1.14‐ and 1.64‐fold with plasmids pUC19 and pET‐32a. Furthermore, the 1‐N‐phenylnaphthylamine assay indicated a 1.71‐fold reduction in cell membrane permeability in the mutant strain. [ABSTRACT FROM AUTHOR]

Tri-(butanediol-monobutyrate) citrate (TBBC) as a new plasticizer for poly(lactic acid) (PLA) was synthesized via a two-step esterification. The chemical structure of TBBC was characterized by ¹H-nuclear magnetic resonance. The studies on solubility parameters, transparence, and storage stability indicated the good miscibility between PLA and TBBC. The glass transition, crystallization, thermal, and mechanical properties of PLA plasticized by TBBC were evaluated. With an increase in TBBC content, the glass transition temperature ([T.sub.g]), melting point ([T.sub.m]), and the cold crystallization temperature ([T.sub.cc]) of plasticized PLA gradually shifted to a lower temperature. The elongation at break and flexibility were greatly improved by the addition of TBBC. After 30 days of storage, PLA plasticized with up to 20 wt% of TBBC exhibited good storage stability and remained the original transparence and mechanical properties. The flexibility of PLA/TBBC films can be tuned by changing TBBC content. The corresponding crystalline morphology and structure were investigated by Polarizing optical microscope and X-ray diffraction as well. This study revealed that TBBC was miscible with PLA and may therefore be a promising plasticizer for PLA-based packaging materials. POLYM. ENG. SCI., 55:205-213, 2015. [C] 2014 Society of Plastics Engineers, INTRODUCTION The environmental and food safety problems have aroused people's concern about biodegradable materials [1]. Biodegradable polymers are considered as food packaging materials to solve serious ecological problems caused by [...]

The preparation of Escherichia coli competent cells by calcium chloride is a common method in molecular biology, but the mechanism is poorly understood. In a previous study, using transcriptomics and proteomics approaches, we found that the expression pattern of the gene loiP was upregulated by CaCl2. In order to investigate the function of the loiP gene in Ca2+- mediated formation of competent cells of E. coli DH5α, the loiP gene deletion strains were constructed by the lambda-derived Red homologous recombination technique. Then, the cell morphology, transformation efficiency, and cell membrane changes of the competent cells of the mutant strain were further explored. Compared with the wild-type E. coli DH5α, the mutant strains have no significant differences in the morphology, growth characteristics, and the permeability of the intracellular membrane. However, the transformation efficiencies of the mutant strains to plasmids of different sizes were significantly reduced, and the permeability of the outer membrane decreased by 2.94 times. These results indicate that the deletion of gene loiP may directly affect the transformation efficiency and outer membrane permeability of E. coli competent cells. [ABSTRACT FROM AUTHOR]