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Understanding the Biology of Organisms Through Studies of Metabolism
Published in Jean F. Challacombe, Metabolic Pathway Engineering, 2021
During the same time frame as the above work, isotopic labeling experiments were used to decipher the flow of carbon, hydrogen, and oxygen through metabolic pathways in living cells. This approach was pioneered by Calvin and his colleagues, who developed metabolite labeling techniques during their pivotal studies of carbon flow during photosynthesis [11–13]. Their labeling technology was adapted to the study of other organisms [14] to trace pathway metabolites and measure metabolite content and enzyme activity in vitro. Other early experimental approaches in metabolomics used gas chromatography and chemical extractions to quantify metabolites and perform metabolic pathway analysis. One example application of this technology resulted in the construction of a hypothetical pathway for citrate accumulation in the yeast Candida lipolytica [15].
Sensors Used to Evaluate Nanotoxicity
Published in Vineet Kumar, Nandita Dasgupta, Shivendu Ranjan, Nanotoxicology, 2018
Isotopic labeling is a technique for tracking the passage of a sample of substance through a system. The water-soluble hydroxylated carbon SWNTs have been labeled with radioactive 125I atoms and then traced to study their distribution in mice, and show a quantitative analysis of carbon nanotubes accumulated in animal tissues (Wang et al. 2004). Two other nuclear imaging modalities have been used for the quantitative analysis of quantum dots, including the single photon emission computed tomography nuclear imaging (SPECT) and positron emission tomography (PET) (Pic et al. 2009). In addition, other workers showed that the bioactivities of fullerene derivatives were greatly altered with the change of outer modified hydroxyl groups (Sayes et al. 2005). Since traditional methods, such as X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR), were not precise enough to determine the exact number of hydroxyl groups, a further measurement of the hydroxyl number was performed using synchrotron radiation X-ray photoemission spectroscopy (SRT), where intensities for the non-functionalized and hydroxylated carbons were achieved (Chen et al. 2005).
Laccase-evoked removal of antibiotics: Reaction kinetics, conversion mechanisms, and ecotoxicity assessment
Published in Critical Reviews in Environmental Science and Technology, 2023
Kai Sun, Mei-Hua Chen, Xue-Min Qi, Dan Hong, Ling-Zhi Dai, Shun-Yao Li, Yi-Chen Lu, Han-Qing Yu
The development of high-resolution mass spectrometry (HRMS) not only overcome these hurdles but also has several advantages, including high resolving power, accurate mass selectivity (m/z, 4 decimal places), and full-scan sensitivity over a wide m/z range (Chen et al., 2019; Hernández et al., 2012). Moreover, the combination of 13C isotopic labeling measurements allows the release of the intrinsic power of isotopic labeling and improves the accuracy of HRMS in identifying the molecular mass and elemental composition of unknown products (Kolkman et al., 2015). In our earlier research, the possible elemental compositions and chemical structures of the formed cross-coupling products during laccase-caused copolymerization were proposed by HRMS in combination with 13C labeling (Sun et al., 2016).