Changes of cellular stress response relatedhsp70andabcb1transcript and Hsp70 protein levels in Siberian freshwater amphipods upon exposure to cadmium chloride in the lethal concentration range

Abstract

The induction of cellular stress response systems, heat shock protein hsp70/Hsp70 and multixenobiotic transporter abcb1, by cadmium chloride (CdCl2) was explored in amphipod species with different stress adaptation strategies from the Lake Baikal area. Based on the lethal concentrations (LC) of CdCl2, the sensitivities of the different species to CdCl2 were ranked (24 hr LC50 in mg/L CdCl2 (mean/95% confidence interval)): Gammarus lacustris (1.7/1.3–2.4) < Eulimnogammarus cyaneus (2.9/2.1–4.0) < Eulimnogammarus verrucosus (5.7/3.8–8.7) < Eulimnogammarus vittatus (18.1/12.4–26.6). Conjugated dienes, indicating lipid peroxidation, were significantly increased after 24 hr exposures to 5 mg/L CdCl2 only in the more CdCl2-sensitive species G. lacustris and E. cyaneus. Upon treatment with 0.54 to 5.8 mg/L CdCl2 for 1, 6 and 24 hrs, hsp70 transcript levels were generally more increased after the longer exposure times and in the more CdCl2-sensitive species. Relating the CdCl2 exposure concentrations to LCx values revealed that across the species the increases of hsp70 transcript levels were comparatively low (up to 2.6-fold) at CdCl2 concentrations ≤LC50. Relative hsp70 transcript levels were maximally increased in E. cyaneus by 5 mg/L CdCl2 ($\hat {=}$LC70) at 24 hrs (9.1-fold increase above the respective control). When G. lacustris was exposed to 5 mg/L CdCl2 ($\hat {=}$LC90) for 24 hrs, the increase in hsp70 was in comparison to E. cyaneus considerably less pronounced (3.0-fold increase in hsp70 levels relative to control). Upon exposure of amphipods to 5 mg/L CdCl2, increases in Hsp70 protein levels compared to untreated controls were highest in E. cyaneus at 1 and 6 hrs (5 mg/L CdCl2 $\hat {=}$ LC70) and in E. verrucosus at 24 hrs (5 mg/L CdCl2 $\hat {=}$ LC45). Thus, when the fold increases in Hsp70 protein levels in the different amphipod species were related to the respective species-specific LCx values a similar bell-shaped trend as for hsp70 transcript levels was seen across the species. Transcript levels of abcb1 in CdCl2exposed individuals of the different amphipod species varied up to 4.7-fold in relation to the respective controls. In contrast to hsp70/Hsp70, abcb1 transcripts in CdCl2 exposed individuals of the different amphipod species did not indicate similar levels of induction of abcb1 at equal LCx levels across the species. Induction of hsp70 and abcb1 genes and Hsp70 proteins by CdCl2 in the lethal concentration range shows that these cellular responses are rather insensitive to CdCl2 stress in the examined amphipod species. Furthermore, the increase of expression of these cellular defense systems at such high stress levels suggests that induction of these genes is not related to the maintenance of normal metabolism but to mitigation of the effects of severe toxic stress.

Application of System Synergy in Environmental Water Monitoring

“…This has been exemplified in the evaluation of the sensitivity of HSPs, particularly HSPs and Hb genes, in the larvae of the aquatic midge Chironomus tentans (Lee, 2006). In amphipod species from the Lake Baikal region, the induction of cellular stress response systems, shock protein hsp70/Hsp70, and multixenobiotic transporter abcb1 by cadmium chloride (CdCl2) was investigated and it was discovered that genes for both proteins were upregulated in the presence of severe toxic stress (Protopopova et al, 2020). When gill and liver tissues of Zacco platypus, a pale chub found in urban rivers and reservoirs were examined, transcriptional responses of genes involving cellular homeostasis (heat-shock protein 70, HSP70; heatshock protein 90, HSP90), metal detoxification (metallothionein, MT), and antioxidation (superoxide dismutase, SOD; catalase, CAT) were found to be upregulated, suggesting low water quality in Singal Lake (Kim et al, 2022).…”

Interactions of Environmental Chemicals and Natural Products With ABC and SLC Transporters in the Digestive System of Aquatic Organisms

“…Thereby, baseline levels of MXR inducibility and activity between different species have been correlated with the amount of pollution present in their habitat ( Kurelec et al, 1995 ; Smital et al, 2000 ). Over the past three decades, fish and other aquatic invertebrates, such as sea urchins and mussels, have been instrumental in understanding MXR transporter interactions with xenobiotics and the chemosensitization effects of so called Transporter-Interfering Chemicals or TICs ( Eufemia et al, 2002 ; Hamdoun et al, 2004 ; Luckenbach and Epel, 2005 , 2008 ; Kwong et al, 2006 ; Stevenson et al, 2006 ; Faria et al, 2011 ; Martins et al, 2020 ; Nicklisch and Hamdoun, 2020 ; Protopopova et al, 2020 ; Nicklisch et al, 2021 ).…”