Proteome Response of Meretrix Bivalves Hepatopancreas Exposed to Paralytic Shellfish Toxins Producing Dinoflagellate Gymnodinium catenatum

Nora Fung-Yee Tam,Fred Wang-Fat Lee,Steven Jing-Liang Xu,Kin-Ka Chan,Christie Ng,Eric Tung-Po Sze,Celia Sze-Nga Kwok

doi:10.3390/jmse9091039

Abstract

Paralytic shellfish toxins (PSTs) contamination of seafood has become a growing global problem. However, the molecular response of bivalves, some of the most popular seafoods, to PSP toxins has seldom been reported and the underlying molecular mechanisms of the interactions between Meretrix meretrix bivalves and PSTs-producing dinoflagellates are scarcely known. This study compared the protein expression profiles between PSP toxin-contaminated and non-PSP toxin contaminated M. meretrix, determined proteome responses and identified potential biomarkers based on feeding experiments. Results showed that the content of total PSP toxins in contaminated bivalves was 40.63 ± 4.08 μg saxitoxin (STX) equivalents per gram, with 95.3% in hepatopancreas, followed by gill (1.82%) and foot (1.79%). According to two-dimensional gel electrophoresis (2-DE), 15 differentially expressed proteins (at least 2-fold difference) between the hepatopancreas of bivalves with and without PSP toxins were detected. Eight of them were successfully identified by MALDI-TOF MS. These were catalase, protein ultraspiracle homolog, G2 and S phase-expression protein, paramyosin, Mn-superoxide dismutase, response regulator receiver domain-containing protein, sarcoplasmic calcium-binding protein and major facilitator superfamily transporters. The differences in the expression levels of the last three proteins involving in cell signaling, structure and membrane transport were 4.2, 5.3 and 4.9-fold, respectively. These proteins could be further developed as potential biomarkers. The other two up-regulated proteins, Mn-superoxide dismutase and catalase, were involved in cell defence mechanisms against oxidative stress, suggesting PSP toxin acts as xenobiotics and poses oxidative stress in bivalves. This study gives insights into the response of bivalves to PSP toxin-producing dinoflagellate at the proteomic level and the potential of using 2-DE to develop specific protein markers in bivalves.

Highlights

Many bivalves like Meretix, Ruditapes, Saccostrea and Mytilus are major foods in our diets
G. catenatum was used in this study because our preliminary work revealed that this dinoflagellate produced a higher amount of Paralytic shellfish toxins (PSTs) than other PST-producing species such as Alexandrium spp
It has been speculated that a high content of C1 or C2 seems to be a characteristic of GYM isolates in general [43]

Summary

Introduction

Many bivalves like Meretix, Ruditapes, Saccostrea and Mytilus are major foods in our diets. Marine bivalve mollusks feed on phytoplankton, but some phytoplankton are toxigenic species producing bioactive toxins that can lead to shellfish poisoning [1,2]. Bivalves have the ability and capacity to accumulate high levels of shellfish poisoning in their tissues during a toxigenic HAB event [3,4]. Such contaminated shellfishes are toxic to human [5,6]. The outbreaks of HABs occurring in coastal water globally cause serious health problems through the consumption of highly toxic bivalve species and lead to severe annual losses of several billions of US dollars in aquaculture areas

Methods

Results

Conclusion