iTRAQ-based proteome profiling of hyposaline responses in zygotes of the Pacific oyster Crassostrea gigas

Integrated transcriptomics and proteomics revealed the distinct toxicological effects of multi-metal contamination on oysters

The Pearl River Estuary (PRE) is the largest estuary in southern China and under high metal stress. In the present study, we employed an integrated method of transcriptomics and proteomics to investigate the ecotoxicological effects of trace metals on the Hong Kong oyster Crassostrea hongkongensis. Three oyster populations with distinct spatial distributions of metals were sampled, including the Control (Station QA, the lowest metal levels), the High Cd (Station JZ, the highest Cd), and the High Zn-Cu-Cr-Ni (Station LFS, with the highest levels of zinc, copper, chromium, and nickel). Dominant metals in oysters were differentiated by principal component analysis (PCA), and theirgene and protein profiles were studied using RNA-seq and iTRAQ techniques. Of the 2250 proteins identified at both protein and RNA levels, 70 proteins exhibited differential expressions in response to metal stress in oysters from the two contaminated stations. There were 8 proteins altered at both stations, with the potential effects on mitochondria and endoplasmic reticulum by Ag. The genotoxicity, including impaired DNA replication and transcription, was specifically observed in the High Cd oysters with the dominating influence of Cd. The structural components (cytoskeleton and chromosome-associated proteins) were impaired by the over-accumulated Cu, Zn, Cr, and Ni at Station LFS. However, enhanced tRNA biogenesis and exosome activity might help the oysters to alleviate the toxicities resulting from their exposure to these metals. Our study provided comprehensive information on the molecular changes in oysters at both protein and RNA levels in responding to multi-levels of trace metal stress.

Analysis of the impact of three phthalates on the freshwater gastropod Physella acuta at the transcriptional level

Plastic pollution is one of the leading environmental problems. Phthalates are widely used plastic additives released into the environment. Although the effects of phthalates on vertebrates have been extensively studied, there is a knowledge gap regarding their effects on invertebrates. This work analyzes the impact of three phthalates, diethyl phthalate (DEP), benzyl butyl phthalate (BBP), and bis-(2-ethylhexyl) phthalate (DEHP), on the gastropod Physella acuta at the molecular level to establish the putative pathways involved in its response to them. By real-time PCR, we obtained the expression profile of 30 genes in animals exposed for 1 week to 0.1, 10, and 1000 μg/L of each phthalate. The genes cover DNA repair, detoxification, apoptosis, oxidative and stress responses, immunity, energy reserves, and lipid transport. The results show that while DEP and DEHP did not alter the mRNA levels, BBP modulated almost all the analyzed genes. It can be concluded that the impact of BBP is extensive at the molecular level. However, it cannot be dismissed that the increase in transcriptional activity is a general response due to this compound's well-known role as an endocrine disruptor. Additional research is needed to elucidate the differences observed in the impact of these compounds on the gastropod P. acuta.

Protein molecular responses of field-collected oysters Crassostrea hongkongensis with greatly varying Cu and Zn body burdens

The oyster Crassostrea hongkongensis is an ideal biomonitor due to its widespread distribution along the coast of Southern China and the ability to hyperaccumulate metals including Cu and Zn. In this study, we conducted the first investigation of the molecular responses to metal hyperaccumulation based on quantitative shotgun proteomics technique and genome information. Gill tissue of oysters collected from the uncontaminated environment (Site 1, 59.6 μg/g and 670 μg/g dry weight for Cu and Zn) displayed significant protein profile differentiation compared to those from a moderately contaminated (Site 2, 1,465 μg/g and 10,170 μg/g for Cu and Zn) and a severely contaminated environment (Site 3, 3,899 μg/g and 39,170 μg/g for Cu and Zn). There were 626 proteins identified to be differentially expressed at Site 3 but only 247 proteins at Site 2. Oysters from a moderately contaminated estuary (Site 2) displayed fewer effects as compared to oysters under severe contamination, with fluctuated small molecule metabolism and enhanced translation process. At Site 3, the induction of reactive oxygen species (ROS) was the main toxicity under the extremely high level of metal stress, which resulted in protein damage. Additionally, the impaired structure of cytoskeleton and modified membrane tracking process at Site 3 oysters led to the blockage or less efficient protein or macromolecule distribution within cells. Nonetheless, proteomic analysis in this study revealed that oysters could partly alleviate the adverse metal effects by boosting the translation process, enhancing the ability to recycle the misfolded proteins, and enhancing the potential to eliminate the excess ROS. Our study demonstrated an adaptive potential of oysters at the protein level to survive under conditions of metal hyper-accumulation.

iTRAQ‑based proteomics analysis of the therapeutic effects of combined anticancer bioactive peptides and oxaliplatin on gastric cancer cells

The combination of chemotherapeutic modalities may be more effective in treating gastric cancer compared with any modality alone. Previous studies have demonstrated that the combination of anticancer bioactive peptides (ACBP) and oxaliplatin (OXA) significantly inhibited the growth of the gastric cancer cell line MKN-45, promoted the apoptosis of MKN-45 cells, and caused an irreversible arrest of the MKN-45 cell cycle in the G2/M phase. In the present study, an isobaric tag for relative and absolute quantitation (iTRAQ)-based quantitative proteomics technique was used to determine the effect of ACBP-OXA treatment on the proteomics profile of MKN-45 cells. Notably, a total of 6,210 proteins were detected. Proteins with a >1.2-fold change in expression (either up- or downregulation) and P<0.05 were considered to be differentially expressed. A total of 256 differentially expressed proteins were identified through alignments with different groups. Compared with the control group, MKN-45 cells treated with ACBP, OXA and ACBP-OXA exhibited 17 (10 up- and 7 downregulated), 111 (27 up- and 84 downregulated) and 128 (53 up- and 75 downregulated) differentially expressed proteins, respectively. Of the 256 differentially expressed proteins, 6 (TPX2, NUSAP1, TOP2A, YAP, MKi-67 and GPC4) were verified by the parallel reaction monitoring method, which revealed that TPX2, NUSAP1, TOP2A, YAP, MKi-67 and GPC4 expression decreased with ACBP-OXA treatment. The cellular localization, functional annotation and biological pathways of differentially expressed proteins were examined by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis. The results indicated that ACBP-OXA may act through the ribosome or the AMP-activated protein kinase (AMPK) signaling pathway, and the AMPK signaling pathway may be an important mediator of the inhibitory effects of ACBP-OXA on MKN-45 gastric cancer cells. In summary, iTRAQ-based proteomics analysis of the effect of ACBP-OXA on MKN-45 cells may guide future therapeutic strategies for gastric cancer. In addition, the present study may help provide new insights into the therapeutic role of combined ACBP and OXA in gastric cancer.