Search

Rationale: Various medium formulations contain essential fatty acids at concentrations ranging from 10 to 100 mg/L. Accurate and precise lipid measurement in media is crucial for monitoring media quality and conducting studies on lipids in the context of cell culture. This study employed two‐dimensional gas chromatography (GC × GC) analyses to offer enhanced resolution, sensitivity, and separation performance compared to GC. Methods: Quantification of fatty acid methyl esters (FAMEs) in a medium was conducted using GC × GC combined with a high‐resolution mass spectrometer and flame ionization detector, considering potential interference from nonionic surfactant Tween 80, which was precipitated and removed by optimizing the concentration of cobalt thiocyanate (CTA) solution during pretreatment. This advanced analytical approach enabled identification of cis and trans isomers of identical molecular weights and determination of the location and number of double bonds in the same carbon number structure. Results: Our analysis identified 36 FAMEs within the C6–C24 region, and a 5% CTA solution was optimal for efficient removal of Tween 80 during lipid extraction. Additionally, this advanced method minimized FAME contamination and loss during pretreatment, thereby significantly reducing the sample volume required to detect trace levels of FAMEs. This improvement led to a fatty acid recovery rate of 106% while maintaining the average relative standard deviation for the target FAMEs of about 3%. Conclusions: Our research paves the way for future investigation into medium quality control and the role of fatty acids in cell culture. This offers the possibility for economical and effective trace quantification of fatty acids in complex media. [ABSTRACT FROM AUTHOR]

Summary: The omics‐based studies are important for identifying characteristic proteins in plants to elucidate the mechanism of ACC deaminase producing bacteria‐mediated salt tolerance. This study evaluates the changes in the proteome of rice inoculated with ACC deaminase producing bacteria under salt‐stress conditions. Salt stress resulted in a significant decrease in photosynthetic pigments, whereas inoculation of Methylobacterium oryzae CBMB20 had significantly increased pigment contents under normal and salt‐stress conditions. A total of 76, 51 and 33 differentially abundant proteins (DAPs) were identified in non‐inoculated salt‐stressed plants, bacteria‐inoculated plants under normal and salt stress conditions respectively. The abundances of proteins responsible for ethylene emission and programmed cell death were increased, and that of photosynthesis‐related proteins were decreased in non‐inoculated plants under salt stress. However, bacteria‐inoculated plants had shown higher abundance of antioxidant proteins, RuBisCo and ribosomal proteins that are important for enhancing stress tolerance and improving plant physiological traits. Collectively, salt stress might affect plant physiological traits by impairing photosynthetic machinery and accelerating apoptosis leading to a decline in biomass. However, inoculation of plants with bacteria can assist in enhancing photosynthetic activity, antioxidant activities and ethylene regulation related proteins for attenuating salt‐induced apoptosis and sustaining growth and development. [ABSTRACT FROM AUTHOR]

Methotrexate (MTX), a folate antagonist, is the anchor drug used to treat several diseases. Therapeutic effects are attributed to intracellular levels of various methotrexate conjugates that are present in the cell as polyglutamates (MTX‐Glu). The present study was conducted to develop a new liquid chromatography‐electrospray ionization‐tandem mass spectrometry (LC‐ESI‐MS/MS)‐based assay to separately quantitate the MTX‐Glu in hair cells, red blood cells, and serum using internal standards. Sample preparation consisted of extraction with an organic solution followed by solid‐phase extraction. The presented methodology was applied for the analysis of methotrexate and its polyglutamates in hair cells, red blood cells, and serum obtained from clinical patients. The developed LC‐ESI‐MS/MS method for the quantitative measurement of MTX‐Glu was both sensitive and precise within the clinically relevant range. This method is possibly be superior with respect to sensitivity, selectivity, and speed than all previously described approaches and can be easily applied in routine clinical tests owing to the combination of a simple pretreatment process with robust LC‐MS/MS. [ABSTRACT FROM AUTHOR]

Helicobacter pylori infection causes a variety of gastrointestinal diseases, including peptic ulcers and gastric cancer. Its colonization of the gastric mucosa of the human stomach is a prerequisite for survival in the stomach. Colonization depends on its motility, which is facilitated by the helical shape of the bacterium. In H. pylori, cross-linking relaxation or trimming of peptidoglycan muropeptides affects the helical cell shape. Csd4 has been identified as one of the cell shape-determining peptidoglycan hydrolases in H. pylori. It is a Zn2+-dependent D,L-carboxypeptidase that cleaves the bond between the γ-D-Glu and the mDAP of the non-cross-linked muramyltripeptide (muramyl-L-Ala-γ-D-Glu- mDAP) of the peptidoglycan to produce the muramyldipeptide (muramyl-L-Ala-γ-D-Glu) and mDAP. Here, the crystal structure of H. pylori Csd4 (HP1075 in strain 26695) is reported in three different states: the ligand-unbound form, the substrate-bound form and the product-bound form. H. pylori Csd4 consists of three domains: an N-terminal D,L-carboxypeptidase domain with a typical carboxypeptidase fold, a central β-barrel domain with a novel fold and a C-terminal immunoglobulin-like domain. The D,L-carboxypeptidase domain recognizes the substrate by interacting primarily with the terminal mDAP moiety of the muramyltripeptide. It undergoes a significant structural change upon binding either mDAP or the mDAP-containing muramyltripeptide. It it also shown that Csd5, another cell-shape determinant in H. pylori, is capable of interacting not only with H. pylori Csd4 but also with the dipeptide product of the reaction catalyzed by Csd4. [ABSTRACT FROM AUTHOR]

The positioning of the nucleosome by ATP-dependent remodellers provides the fundamental chromatin environment for the regulation of diverse cellular processes acting on the underlying DNA. Recently, genome-wide nucleosome mapping has revealed more detailed information on the chromatin-remodelling factors. Here, we report that the Schizosaccharomyces pombe CHD remodeller, Hrp3, is a global regulator that drives proper nucleosome positioning and nucleosome stability. The loss of Hrp3 resulted in nucleosome perturbation across the chromosome, and the production of antisense transcripts in the hrp3? cells emphasized the importance of nucleosome architecture for proper transcription. Notably, perturbation of the nucleosome in hrp3 deletion mutant was also associated with destabilization of the DNA-histone interaction and cell cycle-dependent alleviation of heterochromatin silencing. Furthermore, the effect of Hrp3 in the pericentric region was found to be accomplished via a physical interaction with Swi6, and appeared to cooperate with other heterochromatin factors for gene silencing. Taken together, our data indicate that a well-positioned nucleosome by Hrp3 is important for the spatial-temporal control of transcription-associated processes. [ABSTRACT FROM AUTHOR]