Aquatic Toxicology 159 (2015) 90–98 Contents lists available at ScienceDirect Aquatic Toxicology j o ur na l ho me pag e: www.elsevier.com/locate/aquatox Different effect of dietborne and waterborne Zn exposure on lipid deposition and metabolism in juvenile yellow catfish Pelteobagrus fulvidraco Jia-Lang Zheng a,b,1 , Zhi Luo a,b,∗ , Qing-Ling Zhu a,b , Wei Hu a,b , Mei-Qing Zhuo a,b , Ya-Xiong Pan a,b , Yu-Feng Song a,b , Qi-Liang Chen a,b a Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China b Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan 430070, China a r t i c l e i n f o Article history: Received 30 August 2014 Received in revised form 1 December 2014 Accepted 7 December 2014 Available online 11 December 2014 Keywords: P. fulvidraco Zinc Exposure pathways Lipid metabolism a b s t r a c t Juvenile yellow catfish Pelteobagrus fulvidraco were exposed to 0.04 or 0.35 mg l -1 waterborne Zn, 27.25 or 213.84 mg kg -1 dietary Zn, singly or in combination for 42 days. Growth and lipid metabolism in juvenile yellow catfish were investigated. Growth and survival were significantly inhibited by single waterborne Zn exposure but not by dietary Zn exposure. Dietary Zn addition reduced but waterborne Zn exposure increased hepatic lipid content. In contrast, muscle lipid content was reduced by waterborne Zn exposure but not by dietborne Zn exposure. The single exposure also affected several lipogenic enzymatic activities and expression of genes (in this article gene expression is taken synonymous to mRNA expression) related to lipogenesis and lipolysis. Pearson correlations among lipid content, enzymatic activities and mRNA expression levels were also observed, suggesting that changes at molecular and enzymatic levels may underlie the patterns of lipid metabolism and accordingly affect lipid deposition. For the first time, our study demonstrates the differential effect of different Zn exposure pathways on lipid metabolism at the molecular level in fish, indicating that the exposure route is critical to lipid deposition and metabolism. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Zinc (Zn) is an essential micronutrient required for various func- tions in development such as cell structure and enzyme activities of fish (Watanabe et al., 1997). Compared to terrestrial vertebrates, fish can absorb Zn through two routes: waterborne Zn enters through the gills while dietary Zn is absorbed through the gas- trointestinal tract (Clearwater et al., 2002; Hogstrand et al., 1996). Despite its essential role in many metabolic processes, excess Zn Abbreviations: 6PGD, 6-phosphogluconate; ACC, acetyl-CoA carboxylase; ATGL, adipose triglyceride lipase; BSA, bovine serum albumin; CPT, carnitine palmitoyl- transferase; FAAS, flame atomic absorption spectroscopy; FAS, fatty acid synthase; FBW, final body weight; G6PD, glucose-6-phosphate dehydrogenase; HSL, hormone- sensitive lipase; LPL, lipoprotein lipase; PPAR, peroxisome proliferator-activated receptor; SEM, standard error of mean; SGR, specific growth rate; SREBP, sterol regulatory element-binding protein; WG, weight gain; Zn, zinc. ∗ Corresponding author at: Key Laboratory of Freshwater Animal Breeding, Min- istry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China. Tel.: +86 27 8728 2113; fax: +86 27 8728 2114. E-mail addresses: luozhi99@mail.hzau.edu.cn, luozhi99@aliyun.com (Z. Luo). 1 Present address: Natl Engn Res Ctr Marine Aquaculture, Zhejiang Ocean Univer- sity, Zhoushan 116000, China. both in diets and/or water can be toxic (Spry and Wood, 1989). In China, although the concentration of waterborne Zn in fish- ery water was limited to less than 0.1 mg l -1 (CEPB, 1989), Zn contamination and toxicity in rivers and lakes has posed a signifi- cant environmental hazard for fishery (Qiao et al., 2007). In some coastal zone, waterborne Zn concentration reaches 100 mg l -1 (Wu et al., 2007). At present, Zn toxicity is a well-studied topic in the field of aquatic toxicology. However, most studies on the toxic effects of Zn have focused on the waterborne exposure pathway (De Schamphelaere and Janssen, 2004; Giardina et al., 2009; van Dyk et al., 2007; Zheng et al., 2011). Limited number of studies has focused on dietary Zn exposure pathway in fish, mainly concen- trating on dietary Zn requirement (Köck and Bucher, 1997; Kjoss et al., 2006; Luo et al., 2011; Overnell et al., 1988; Sappal et al., 2009; Wekell et al., 1986). Furthermore, investigations in Zn toxic- ity have mainly used growth performance, antioxidant responses and histopathological damage as the endpoints. Recently, stud- ies in our laboratory indicated that waterborne Zn exposure could influence lipid deposition and metabolism in yellow catfish (Zheng et al., 2013). Thus, since the gill is the major route of water- borne Zn uptake and Zn uptake through the intestine is significant for dietary Zn exposure, it is imperative and also interesting to http://dx.doi.org/10.1016/j.aquatox.2014.12.003 0166-445X/© 2014 Elsevier B.V. All rights reserved.