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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]

Mass spectrometry (MS)-based intact mass analysis and structural characterization of biotherapeutic proteins such as monoclonal antibodies (mAbs) are a crucial characterization approach from upstream drug development to downstream product analysis. Due to various endogenous modifications leading to the structural heterogeneity and several N-linked glycan species resulting in macro-heterogeneity, it is challenging to characterize the mAbs. Hence, it is essential to understand the micro-heterogeneity of such proteins with high level of complexity which may vary in charge, size, or hydrophobicity. The development of high-throughput native separation techniques hyphenated with MS with high sensitivity and excellent mass accuracy has improved the top/middle down analysis, intact mass detection, subunit analysis, enhanced sequence coverage, and accurate localization of site-specific modifications. In this review, we have focused on the critical inroads taken for the improvement in MS-based techniques to resolve the challenges related to analysis of mAbs. Various MS-based techniques and their role in high-order structural analysis and the progress in software development have been explained, and further, the challenges remaining have been discussed. [ABSTRACT FROM AUTHOR]

Cav1.2 channel phosphorylation plays an important role in regulating neuronal plasticity by action potential-dependent Ca2+ entry. Most studies of Cav1.2 regulation by phosphorylation have been reported in heart and muscles. Here, we identified phosphorylation sites of neuronal Cav1.2 channel protein purified from rat brain using mass spectrometry. The functional characterization of these phosphorylation sites showed altered voltage-dependent biophysical properties of the channel, without affecting current density. These results show that neuronal Cav1.2 channel is regulated by phosphorylation in a complex mechanism involving multiple phosphorylation sites. [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]

Abstract Background The rice roots are highly salt-sensitive organ and primary root growth is rapidly suppressed by salt stress. Sucrose nonfermenting 1-related protein kinase2 (SnRK2) family is one of the key regulator of hyper-osmotic stress signalling in various plant cells. To understand early salt response of rice roots and identify SnRK2 signaling components, proteome changes of transgenic rice roots over-expressing OSRK1, a rice SnRK2 kinase were investigated. Results Proteomes were analyzed by two-dimensional electrophoresis and protein spots were identified by LC-MS/MS from wild type and OSRK1 transgenic rice roots exposed to 150 mM NaCl for either 3 h or 7 h. Fifty two early salt -responsive protein spots were identified from wild type rice roots. The major up-regulated proteins were enzymes related to energy regulation, amino acid metabolism, methylglyoxal detoxification, redox regulation and protein turnover. It is noted that enzymes known to be involved in GA-induced root growth such as fructose bisphosphate aldolase and methylmalonate semialdehyde dehydrogenase were clearly down-regulated. In contrast to wild type rice roots, only a few proteins were changed by salt stress in OSRK1 transgenic rice roots. A comparative quantitative analysis of the proteome level indicated that forty three early salt-responsive proteins were magnified in transgenic rice roots at unstressed condition. These proteins contain single or multiple potential SnRK2 recognition motives. In vitro kinase assay revealed that one of the identified proteome, calreticulin is a good substrate of OSRK1. Conclusions Our present data implicate that rice roots rapidly changed broad spectrum of energy metabolism upon challenging salt stress, and suppression of GA signaling by salt stress may be responsible for the rapid arrest of root growth and development. The broad spectrum of functional categories of proteins affected by over-expression of OSRK1 indicates that OSRK1 is an upstream regulator of stress signaling in rice roots. Enzymes involved in glycolysis, branched amino acid catabolism, dnaK-type molecular chaperone, calcium binding protein, Sal T and glyoxalase are potential targets of OSRK1 in rice roots under salt stress that need to be further investigated.

Biometric authentication offers advantages over current security practices. Unlike keys and tokens, biometrics are never lost or stolen. Unlike passwords, biometrics cannot be forgotten. However, existing biometric systems are with controversy: once divulged, they are compromised forever. To this end, this paper explores a truly cancelable brain-based biometric system for the first time. Specifically, we present a new psychophysiological protocol via non-volitional brain response for trustworthy user authentication, with an application example of smart headwear. More specifically, we address the following research challenges in a theoretical and experimental combined manner: (1) how to generate reliable brain responses with sophisticated visual stimuli; (2) how to acquire effective brain response and analyze unique features in them for authentication; and (3) how to reset and change brain biometrics when the current biometric credential is divulged. To evaluate the performance of the proposed system, we conducted a pilot study and achieved an $f$ f -score accuracy of 95.46 percent and equal error rate (EER) of 2.503 percent, thereby demonstrating the potential feasibility of neurofeedback based biometrics for smart headwear applications. Further, the cancelability study proves the effectiveness of the reset brain password. To the best of our knowledge, it is the first in-depth research study on truly cancelable brain biometrics. [ABSTRACT FROM AUTHOR]

An inter-laboratory study was performed to evaluate the performance of a method developed for the quantification of enrofloxacin in chicken meat. Liquid-liquid extraction combined with a clean-up procedure based on solid-phase extraction followed by a liquid chromatography-tandem mass spectrometric method was used by three individual laboratories. All the investigated results of calibration curves and limits of quantification were within the acceptable range for regulatory testing of enrofloxacin. The three laboratories received blind a certified reference material to analyze in triplicate and assess using statistical analysis. From the results, no statistical differences were found between the laboratories in the precision of the method. Additionally, all the results of the z-score, which is an indication of fixed interval bias criteria for accuracy from the laboratories, fell within the allowable limits (±2σ). Based on this proficiency testing by inter-laboratory comparisons, the analytical method including the sample preparation step was proven to be applicable. [ABSTRACT FROM AUTHOR]

The objective of this study is to demonstrate characteristics of a y-type high molecular weight glutenin subunit (D1y HMW-GS) at Glu-D1 found in IT212991, a North Korean landrace wheat compared to Dy12 and Dy12.K as a novel HMW-GS in JB20, a Korean wheat line onto molecular analyses as PCR, cloning, DNA sequencing, and RP-HPLC and proteomic analyses as sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional electrophoresis (2-DE), Fourier-transform mass spectrometry (LTQ-FT-MS). The D1y of IT212991 was identified to have faster electrophoretic mobility than that of Dy12 by SDS-PAGE. HMW-GS components of IT212991 were identified to be different from Chinese Spring (CS) and JB20, a Korean wheat line by RP-HPLC. The result of mass spectrometric analysis, the D1y of IT212991 (68510.8 Da) was similar to that of Dy12.K of JB20 (68514.4 Da), and lower than Dy12 of CS (69151.2 Da). The result of LTQ-FT-MS based on 2-DE, the D1y of IT212991 was identified to be similar with Dy12 corresponding to the protein function as ‘Glutenin, high molecular weight subunit 12’. The D1y encoding the D1y of IT212991 was identified to consist of 652 amino acid sequences corresponding to 1962 bp according to DNA sequencing. The gene was identified to have a insertion and deletion (InDel) corresponding to 18 bp sequences ‘AACAGGACAAGGGCAACA’ compared to ordinary Dy12 gene. It was demonstrated that the D1y of IT212991 is the same as Dy12.K. [ABSTRACT FROM AUTHOR]