Transcriptional response of marine medaka (Oryzias javanicus) on exposure to toxaphene

Comparative phosphoproteomics analysis provides insights into the responses of Chilo suppressalis to sublethal chlorantraniliprole exposure

BACKGROUND

Sublethal exposure to insecticides causes changes in insect behaviors and physiologies including feeding, mobility, communication, hormone homeostasis, development and fecundity, however, the underlying molecular mechanisms were largely unclear. Our previous studies revealed that sublethal chlorantraniliprole exposure disturbed the hormone homeostasis, reduced the weight and longevity and prolonged the developmental duration of Chilo suppressalis. In the present study, the potential phosphorylation modification regulation mechanisms in C. suppressalis in response to sublethal chlorantraniliprole exposure were explored using comparative and quantitative phosphoproteomics.

RESULTS

A total of 2640 phosphopeptides belonging to 1144 phosphoproteins were identified, among which 446 phosphopeptides derived from 303 unique phosphoproteins were differentially phosphorylated between the chlorantraniliprole-treated and control larvae. The phosphorylation levels of differentially phosphorylated phosphopeptides were further validated using parallel reaction monitoring (PRM). Functional classification and protein-protein interaction of the differentially phosphorylated proteins (DPPs) were analyzed. Generalized analysis of the DPPs and the differentially expressed genes (DEGs) identified in our previous study showed that sublethal chlorantraniliprole exposure significantly changed the transcription and phosphorylation levels of genes/proteins associated with carbohydrate and lipid metabolism, cytoskeleton, signal transduction, transcription, translation and post-translational modification, leading to the dysfunctions of energy metabolism, transcription regulation, protein synthesis and modification, and signal transduction in C. suppressalis. Further analysis of the phosphorylation motifs in DPPs revealed that the MAPKs, CDKs, CaMK II, PKA, PKC and CK II protein kinases might be directly responsible for the phosphoproteomics response of C. suppressalis to chlorantraniliprole treatment.

CONCLUSION

Our results provide abundant phosphorylation information for characterizing the protein modification in insects, and also provide valuable insights into the molecular mechanisms of insect post-translational modifications in response to sublethal insecticide exposure. © 2023 Society of Chemical Industry.

DDRT-PCR approaches applied for preeminent results in the isolation of DETs from fish brain tissues

Differential Display (DD) is a technique widely used in studies of differential expression. Most of these analyses, especially those involving fish species, are restricted to species from North America and Europe or to commercial species, as salmonids. Studies related to South American fish species are underexplored. Thus, the present work aimed to describe DD technique modifications in order to improve outcomes related to the isolation of DETs (Differentially Expressed Transcripts), using Leporinus macrocephalus, a large commercially exploited South American species, as a fish design. Different DDRT-PCR approaches were applied to brain samples and the products of the reactions were analyzed on 6% polyacrylamide gels stained with 0.17% Silver Nitrate (AgNO3). The use of PCR reactions under high stringency conditions and longer oligonucleotides based on VNTR (Variable Number of Tandem Repeats) core sequences led to better results when compared to low stringency PCR conditions and the use of decamer oligonucleotides. The improved approach led to the isolation of differentially expressed transcripts on adult males and females of L. macrocephalus. This study indicates that some modifications on the DDRT-PCR method can ensure isolation of DETs from different fish tissues and the development of robust data related to this approach.

A genome-wide screen identifies yeast genes required for tolerance to technical toxaphene, an organochlorinated pesticide mixture

Exposure to toxaphene, an environmentally persistent mixture of chlorinated terpenes previously utilized as an insecticide, has been associated with various cancers and diseases such as amyotrophic lateral sclerosis. Nevertheless, the cellular and molecular mechanisms responsible for these toxic effects have not been established. In this study, we used a functional approach in the model eukaryote Saccharomyces cerevisiae to demonstrate that toxaphene affects yeast mutants defective in (1) processes associated with transcription elongation and (2) nutrient utilization. Synergistic growth defects are observed upon exposure to both toxaphene and the known transcription elongation inhibitor mycophenolic acid (MPA). However, unlike MPA, toxaphene does not deplete nucleotides and additionally has no detectable effect on transcription elongation. Many of the yeast genes identified in this study have human homologs, warranting further investigations into the potentially conserved mechanisms of toxaphene toxicity.

Toxaphene affects the levels of mRNA transcripts that encode antioxidant enzymes in Hydra

We evaluated toxaphene-induced acute toxicity in Hydra magnipapillata. The median lethal concentrations of the animals (LC(50)) were determined to be 34.5 mg/L, 25.0 mg/L and 12.0 mg/L after exposure to toxaphene for 24 h, 48 h and 72 h, respectively. Morphological responses of hydra polyps to a range of toxaphene concentrations suggested that toxaphene negatively affects the nervous system of H. magnipapillata. We used real-time quantitative PCR of RNA extracted from polyps exposed to two concentrations of toxaphene (0.3 mg/L and 3 mg/L) for 24 h to evaluate the differential regulation of levels of transcripts that encode six antioxidant enzymes (CAT, G6PD, GPx, GR, GST and SOD), two proteins involved in detoxification and molecular stress responses (CYP1A and UB), and two proteins involved in neurotransmission and nerve cell differentiation (AChE and Hym-355). Of the genes involved in antioxidant responses, the most striking changes were observed for transcripts that encode GPx, G6PD, SOD, CAT and GST, with no evident change in levels of transcripts encoding GR. Levels of UB and CYP1A transcripts increased in a dose-dependent manner following exposure to toxaphene. Given that toxaphene-induced neurotoxicity was not reflected in the level of AChE transcripts and only slight accumulation of Hym-355 transcript was observed only at the higher of the two doses of toxaphene tested, there remains a need to identify transcriptional biomarkers for toxaphene-mediated neurotoxicity in H. magnipapillata. Transcripts that respond to toxaphene exposure could be valuable biomarkers for stress levels in H. magnipapillata and may be useful for monitoring the pollution of aquatic environments.