[Application of multiomics mass spectrometry in the research of chemical exposome].

Environmental factors, such as environmental pollutants, behaviors, and lifestyles, are the leading causes of chronic noncommunicable diseases. Estimates indicate that approximately 50% of all deaths worldwide can be attributed to environmental factors. The exposome is defined as the totality of human environmental (i.e., all nongenetic) exposures from conception, including general external exposure (e.g., climate, education, and urban environment), specific external exposure (e.g., pollution, physical activity, and diet), and internal exposure (e.g., metabolic factors, oxidative stress, inflammation, and protein modification). As a new paradigm, this concept aims to comprehensively understand the link between human health and environmental factors. Therefore, a comprehensive measurement of the exposome, including accurate and reliable measurements of exposure to the external environment and a wide range of biological responses to the internal environment, is of great significance. The measurement of the general external exposome depends on advances in environmental sensors, personal-sensing technologies, and geographical information systems. The determination of exogenous chemicals to which individuals are exposed and endogenous chemicals that are produced or modified by external stressors relies on improvements in methodology and the development of instrumental approaches, including colorimetric, chromatographic, spectral, and mass-spectrometric methods. This article reviews the research strategies for chemical exposomes and summarizes existing exposome-measurement methods, focusing on mass spectrometry (MS)-based methods. The top-down and bottom-up approaches are commonly used in exposome studies. The bottom-up approach focuses on the identification of chemicals in the external environment (e.g., soil, water, diet, and air), whereas the top-down approach focuses on the evaluation of endogenous chemicals and biological processes in biological samples (e.g., blood, urine, and serum). Low- and high-resolution MS (LRMS and HRMS, respectively) have become the most popular methods for the direct measurement of exogenous and endogenous chemicals owing to their superior sensitivity, specificity, and dynamic range. LRMS has been widely applied in the targeted analysis of expected chemicals, whereas HRMS is a promising technique for the suspect and unknown screening of unexpected chemicals. The development of MS-based multiomics, including proteomics, metabolomics, epigenomics, and spatial omics, provides new opportunities to understand the effects of environmental exposure on human health. Metabolomics involves the sum of all low-molecular-weight metabolites in a living system. Nontargeted metabolomics can measure both endogenous and exogenous chemicals, which would directly link exposure to biological effects, internal dose, and disease pathobiology, whereas proteomics could play an important role in predicting potential adverse health outcomes and uncovering molecular mechanisms. MS imaging (MSI) is an emerging technique that provides unlabeled in-depth measurements of endogenous and exogenous molecules directly from tissue and cell sections without changing their spatial information. MSI-based spatial omics, which has been widely applied in biomarker discovery for clinical diagnosis, as well as drug and pollutant monitoring, is expected to become an effective method for exposome measurement. Integrating these response measurements from metabolomics, proteomics, spatial omics, and epigenomics will enable the generation of new hypotheses to discover the etiology of diseases caused by chemical exposure. Finally, we highlight the major challenges in achieving chemical exposome measurements.

Effects of a Dissostichus mawsoni-CaM recombinant proteins feed additive on the juvenile orange-spotted grouper (Epinephelus coioides) under the acute low temperature challenge.

The effects of Dissostichus mawsoni-Calmodulin (Dm-CaM) on growth performance, enzyme activities, respiratory burst, MDA level and immune-related gene expressions of the orange-spotted grouper (Epinephelus coioides) exposed to the acute low temperature stress were evaluated. The commercial diet supplemented with Dm-CaM protein was fed to the groupers for 6 weeks. No significant difference was observed in the specific growth rates, weight gains and survivals. After the feeding trial, the groupers were exposed to acute low temperature challenge. The groupers fed with Dm-CaM additive diet showed a significant decrease in the respiratory burst activity, while the blood cell number increased significantly at 25 °C by comparing with the control and additive control group. The enzymatic activity of SOD, ACP and ALP increased significantly in Dm-CaM additive group, while MDA level maintained stable with the lowest value. qRT-PCR analysis indicated that the up-regulated transcript expressions of CaM, C3, SOD2, LysC and HSPA4 were observed in Dm-CaM additive group. These results indicated that Dm-CaM additive diet may regulate the grouper immune response to the acute low temperature challenge.

Effects of a recombinant complement component C3b functional fragment α2MR (α2-macroglobulin receptor) additive on the immune response of juvenile orange-spotted grouper (Epinephelus coioides) after the exposure to cold shock challenge.

The effects of Ec-α2MR (Epinephelus coiodes-α2-macroglobulin receptor) on growth performance, enzymatic activity, respiratory burst, MDA level, total antioxidant capacity, DPPH radical scavenging percentage and immune-related gene expressions of the juvenile orange-spotted grouper were evaluated. The commercial diet supplemented with α2MR additive was used to feed the orange-spotted grouper for six weeks. Although a slight increase was observed in the specific growth rate, survival rate and weight gain, no significance was observed among different group. After the feeding trial, the groupers were exposed to cold stress. Respiratory burst activity and MDA level decreased significantly in α2MR additive group by comparing with the control and additive control group, while a sharp increase of ACP activity, ALP activity, total antioxidant capacity and DPPH radial scavenging percentage was observed in α2MR additive group. qRT-PCR analyses confirmed that the up-regulated mRNA expressions of C3, TNF1, TNF2, IL-6, CTL, LysC, SOD1 and SOD2 were observed in α2MR additive group at 20 °C. These results showed that α2MR additive may moderate the immune response in grouper following cold shock challenge.

Optimal conditions for expressing a complement component 3b functional fragment (α2-macroglobulin receptor) gene from Epinephelus coioides in Pichia pastoris.

The α2-macroglobulin receptor (α2MR) is a major domain of complement component 3b, which may play an important role in regulating the downstream complement system in teleosts. In order to characterize the domain thoroughly larger than currently available quantities are required. Thus, in this study the Epinephelus coioides α2MR (Ec-α2MR) was expressed and secreted by the methylotrophic yeast Pichia pastoris with variations in pH and induction time to identify optimal production conditions. At pH 5.5 with 48h induction 13mg of Ec-α2MR (ca. 90% purity) was obtained from 500ml of culture. The Ec-α2MR protein product was validated by MALDI-TOF MS sequence analysis, and both Western blotting and ELISAs demonstrated that it possessed the expected activity, binding to C3b or C3b homolog antibodies, and thus can be used for future studies of the interactions and functions of complement proteins in teleosts.

Molecular cloning, characterization and expression analysis of tumor suppressor protein p53 from orange-spotted grouper, Epinephelus coioides in response to temperature stress.

The tumor suppressor protein p53 is a critical component of cell cycle checkpoint responses. It upregulates the expression of cyclin-dependent kinase inhibitors in response to DNA damage and other cellular perturbations, and promotes apoptosis when DNA repair pathways are overwhelmed. In the present study, the cDNA of p53 from the orange-spotted grouper (Epinephelus coioides) (Ec-p53) was cloned by the combination of homology cloning and rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of Ec-p53 was of 1921 bp, including an open reading frame (ORF) of 1143 bp encoding a polypeptide of 380 amino acids with predicted molecular weight of 42.3 kDa and theoretical isoelectric point of 7.0. Quantitative real-time PCR (qRT-PCR) assays revealed that Ec-p53 was ubiquitously expressed in all the examined tissues but with high levels in intestine and liver of the orange-spotted grouper. In addition, we measured the DNA damage and apoptosis in the blood cells and the percentage of dead and damaged blood cells. Our results suggest that oxidative stress and DNA damage occurred in grouper in conditions where the temperature was 15 ± 0.5 °C. Furthermore, qRT-PCR and western blot confirmed that low temperature stress induced upregulation of Ec-p53 in the mRNA and protein levels. These results suggest that low temperature-induced oxidative stress may cause DNA damage or apoptosis, and cooperatively stimulate the expression of Ec-p53, which plays a critical role in immune defense and antioxidant responses.

Fatty acid binding protein 10 in the orange-spotted grouper (Epinephelus coioides): characterization and regulation under pH and temperature stress.

We have isolated and characterized a fatty acid binding protein from the liver of the orange-spotted grouper (Epinephelus coioides). Amino acid sequence similarity of the Ec-FABP (E. coioides-FABP) was highest to FABP10s isolated from the livers of catfish, chicken, salamander and iguana. The open-reading frame of the Ec-FABP codes for a protein of 14.0 kDa with a calculated isoelectric point of 8.5. We first expressed a FABP10 protein from orange-spotted grouper (E. coioides) in Pichia pastoris, and then characterized the antioxidative potential of our recombinant Ec-FABP by DCF fluorescence assay. RT-PCR assays showed that endogenous Ec-FABP mRNA is most strongly expressed in liver with the most abundance and intestine. Change in the groupers' blood cells respiratory burst activity was examined during and after exposure to the pH and temperature stress using flow cytometry. Further analysis of Ec-FABP gene expression in liver tissue by quantitative real-time PCR demonstrated that Ec-FABP transcript levels increased when the fish were exposed to both pH and temperature stress, but the time when its mRNA expression level peaked differed under these stresses. Western blot analyses confirmed that the Ec-FABP protein was strongly expressed in the liver after exposure to the pH and temperature stress. These results suggest that Ec-FABP expression is stimulated by pH and temperature stress and that it may play important roles in general adaptive and antioxidant responses.

Molecular characterization and functional analysis of a complement C3 molecule in the orange-spotted grouper (Epinephelus coioides).

Complement component C3 is a key molecule in the complement system whose activation is essential for all the important functions performed by this system. In this study, we examined a temperature-subtracted library from the orange-spotted grouper (Epinephelus coioides), and identified a sequence with high similarity to other complement C3 proteins. Rapid amplification of the cDNA ends (RACE) yielded the full open reading frame of this protein, and subsequent analysis indicated that the Ec-C3 (E. coioides-C3) gene encodes a protein of 1657 amino acid residues with a molecular mass of 184.56 kDa. The deduced amino acid sequence showed that Ec-C3 has conserved residues and domains known to be critical for C3 function. RT-PCR assays showed that under normal physiological conditions Ec-C3 mRNA is most strongly expressed in the liver, but relatively high levels were also found in many other tissues, including intestine, muscles, gills, hemocytes, heart, spleen, head, kidney and brain. Further analysis of Ec-C3 gene expression in liver tissue by quantitative real-time PCR demonstrated that Ec-C3 transcript levels increased when the fish were exposed to both pH and temperature stress, but the time when its expression level peaked differed under these stresses. The results show that Ec-C3 mRNA expression in the orange-spotted grouper is influenced by pH and temperature stress and that Ec-C3 may play an important role in antioxidation mechanisms.