Antioxidant enzymes, HSP70 and Ubiquitin levels in Laeonereis acuta from the Argentinean coast

Abstract

Introduction: Polychaetes have been used as indicator species of environmental contamination, utilized to assess the effects of pollutants in organisms and employed as sensitive monitors of water quality [1]. The aim of this study was to investigate the tidal- and site-dependent effects in Laeonereis acuta by measuring the heat shock proteins (HSP70), Ubiquitin and oxidative stress enzymes: superoxide dismutase (SOD) and catalase (CAT).

Materials and methods: The Argentinean nereidid, L. acuta (n = 76), were collected in the low-tide-I and high-tide-S zones of different coastal sites near Mar del Plata: Samborombon; Quequén; Bahia Blanca and Mar Chiquita. The samples treatment and biomarkers determination were performed following Madeira et al. [2]. The statistics analysis of the results was performed using a non-parametric test (Kruskal-Wallis) to assess differences between sampling sites and between tidal zones.

Results: The results from antioxidant enzymes (CAT and SOD), HSP70 and Ubiquitin are shown in Figure 1. The highest levels of biomarkers were observed in samples from Mar Chiquita. Significant differences between samples from low and high tide zones were detected at Quequén for HSP70 and at B. Blanca for CAT (Figure 1). The statistical analysis between sites and same tidal zone revealed significant differences (p < 0.05) between Quequén-S and Mar Chiquita-S (for HSP70, Ubiquitin, CAT and SOD) and between B. Blanca-I and Mar Chiquita-I (for HSP, CAT and SOD). Significant differences (p < 0.05) were also found between Quequén-I and B. Blanca-I for HSP and between Samborombon-I and B. Blanca-I and Mar Chiquita-I, for Ubiquitin. Significant differences (p < 0.05) were also detected between Samborombon-S and Mar Chiquita-S and between Quequén- S and B. Blanca-S, both for SOD. Moreover, significant differences were found between Quequén-I and Mar Chiquita-I, for SOD.

Figure 1. Biomarkers (mean ± sd) determined in organisms from different sites of Argentinean coast. Legend: I (low-tide zone); S (high-tide zone). *Significant differences (p<0.05) between tidal zones from the same site.

Discussion and conclusions: In general, the results show that Mar Chiquita organisms seem to be under more stressful conditions than organisms from the other sites, suggesting that organisms are exposed to contaminants or other stress inducing factors, which is in accordance with previous studies [3]. Although B. Blanca and Samborombom are known to be impacted by pollutants [4,5], biomarker levels are lower than in Mar Chiquita. We can hypothesize that in these sites the stress inducing factors, such as pollution, are less intense than in Mar Chiquita. Nonetheless, more analysis should be performed to clarify the biomarkers responses in each site.

Acknowledgements

This work was supported by the Unidade de Ciências Biomoleculares Aplicadas-UCIBIO which is financed by national funds from FCT/MEC (UID/Multi/04378/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007728).