Shouxiang Sun,Yumei Wang,Pei-Tian Goh,Mónica Lopes-Marques,L. Filipe C. Castro,Óscar Monroig,Meng-Kiat Kuah,Xiaojuan Cao,Alexander Chong Shu-Chien,Jian Gao
Elongation of very long-chain fatty acid (Elovl) proteins are key enzymes that catalyze the rate-limiting step in the fatty acid elongation pathway. The most recently discovered member of the Elovl family, Elovl8, has been proposed to be a fish-specific elongase with two gene paralogs described in teleosts. However, the biological functions of Elovl8 are still to be elucidated. In this study, we showed that in contrast to previous findings,elovl8is not unique to teleosts, but displays a rather unique and ample phylogenetic distribution. For functional determination, we generatedelovl8a(elovl8a−/−) andelovl8b(elovl8b−/−) zebrafish using CRISPR/Cas9 technology. Fatty acid composition in vivo and zebrafish liver cell experiments suggest that the substrate preference of Elovl8 overlapped with other existing Elovl enzymes. Zebrafish Elovl8a could elongate the polyunsaturated fatty acids (PUFAs) C18:2n-6 and C18:3n-3 to C20:2n-6 and C20:3n-3, respectively. Along with PUFA, zebrafish Elovl8b also showed the capacity to elongate C18:0 and C20:1. Gene expression quantification suggests that Elovl8a and Elovl8b may play a potentially important role in fatty acid biosynthesis. Overall, our results provide novel insights into the function of Elovl8a and Elovl8b, representing additional fatty acid elongases not previously described in chordates.Keywords:elovl8;gene knockout;zebrafish;fatty acid synthesis
Marine hydrosphere is in grave danger if extreme weather conditions, such as high temperatures and heat waves, become the norm. The functional characteristics of nano Zn oxides (nZnO) might provide a “booster substance” that helps marine species to endure environmental stress. In the present study, physiological indicators and simulated severe environments were used to evaluate the antioxidative ability of nZnO in marine rabbitfish Siganus fuscescens, with an aim to help them resist extreme environmental stress. Rabbitfish were exposed to different diets with ZnSO4 and nZnO at the optimum requirement level (Zn content of 62.5 μg g−1), and then challenged with a low dissolved oxygen concentration and higher temperature. We demonstrated that dietary nZnO promoted the anti-oxidation defense system of the rabbitfish by improving the activities of the antioxidant enzymes, i.e., catalase (CAT), superoxide dismutase (SOD), and the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio without tissue damage. Compound stressors reduced the median survival duration of the rabbitfish from 4.25 h to 2.5 h (dietary exposure) and 9 h to 5.75 h (dietary nZnO exposure) compared to single environmental stress. nZnO downregulated the HIF gene expression and increased the prolyl hydroxylase (PHD) activity in the liver of the rabbitfish. After 10 h of extreme environmental exposure, the gene expression results indicated that nZnO inhibited the NF-κB/IL-1β/IL-6 pathway and TNF-α/Bcl-2/Bax/caspase 9 pathway and activated the akt/mTOR/elovl5 and elovl8 pathway of the rabbitfish to maintain the resilience of the fish under the extreme environment. These results strongly suggested that nZnO may improve the anti-oxidation ability of fish to resist extreme environments.
危险品化学品经营许可证（带存储）