Effects of Acute and Chronic Exposure to Semicarbazide on the Sea Cucumber Apostichopus japonicus

Xiuhui Tian,Huan Liu,Dianfeng Han,Huihui Liu,Yingjiang Xu,Bin Wang,Huawei Zhang,Yanmei Cui,Xianghong Gong,Huanjun Li,Xiuzhen Zhang,Quanli Zhou

doi:10.3389/fenvs.2021.682221

Abstract

The effects of acute and chronic exposure to semicarbazide were carried out on the sea cucumber Apostichopus japonicus. A half-maximal lethal concentration of 3.72 g/L of semicarbazide hydrochloride (95% confidence interval 3.43–4.02 g/L) was deduced. At 20, 4, and 2% of the half-maximal lethal concentrations, a 28-days exposure induced morphological alterations, oxidative stress, and acetylcholinesterase (AChE) activity in the respiratory tree, intestinal tract, and longitudinal muscle of A. japonicus. Exposure to 20% of the half-maximal lethal concentration resulted in lesions in the respiratory tree and disintegration in the intestinal tract. Exposure to lower concentration induced a gradual accumulation of lesions in the respiratory tree, intestinal tract, and longitudinal muscle. Levels of markers of oxidative stress and neurotransmission, including superoxide dismutase (SOD), catalase, and AChE, were increased during the initial days of exposure and then decreased. The activity of SOD, catalase, and AChE were highest in A. japonicus exposed to 4%, followed by 20 and 2% of the half-maximal lethal concentration at the same time. At the later stages of the 28-days exposure, marker levels were decreased and close to levels in the control groups. Non-targeted metabolomics indicated that significantly different metabolites were screened out, 28 in the positive ion mode and 38 in the negative ion mode, impairments in neurological function, osmotic pressure regulation, energy metabolism, and protein digestion and absorption following exposure of A. japonicus to semicarbazide. KEGG pathway enrichment showed that the exposure affected pathways related to ABC transporters, central carbon metabolism in cancer, protein digestion and absorption, aminoacyl-tRNA biosynthesis, and biosynthesis of unsaturated fatty acids.

Highlights

Semicarbazide, termed carbamoylhydrazine, was a photochromic dye used in thermal recording paper and an intermediate in the synthesis of prednisone and adrenobazone (Nardelli et al, 1965; Raja et al, 2017; Tarek et al, 1986)
A. japonicus exposed to 5.00 g/L semicarbazide curled up into a ball, the flesh became blunt, the internal organs expelled, and the skin festered until death
Different metabolites were selected by the importance of variables with projection scores (VIP) value greater than one and p values less than 0.05

Summary

Introduction

Semicarbazide, termed carbamoylhydrazine, was a photochromic dye used in thermal recording paper and an intermediate in the synthesis of prednisone and adrenobazone (Nardelli et al, 1965; Raja et al, 2017; Tarek et al, 1986). Semicarbazide was a minor product of the decomposition of azodicarbonamide at high temperatures (Becalski et al, 2004; Becalski et al, 2006). Semicarbazide can lower the concentration of endogenous 17β-estradiol, inhibiting the maturation of the ovary in female zebrafish eventually (Yu et al, 2016). Semicarbazide can alter the testicular morphology in male zebrafish and lower the testicular somatic index, reducing ability of reproductive regulatory (Yu et al, 2017). Semicarbazide has been evidenced to be an inhibitor of mediated effect between GAD and GABA, which has been verified in the reproductive system of the male zebrafish, causing disorder through GABA in males (Yu et al, 2017). The Shandong Peninsula Blue Economic Zone, subjected to a national development strategy in China, was an area where the pollutants could affect the marine organisms and the humans negatively who consumed them (Fleming et al, 2006; Partelow et al, 2015)

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