Hepatic transcriptome analysis and identification of differentially expressed genes response to dietary oxidized fish oil in loach Misgurnus anguillicaudatus.

Yin Zhang,Jie Yan,Yanxing Wei,Xiaojuan Cao,Xiao Liang,Jian Gao,Longfei Huang,Yang Li,Hanping Wang

doi:10.1371/journal.pone.0172386

Abstract

RNA sequencing and short-read assembly were utilized to produce a transcriptome of livers from loaches (Misgurnus anguillicaudatus) fed with three different diets respectively containing fresh fish oil (FO group), medium oxidized fish oil (MO group) and high oxidized fish oil (HO group). A total of 60,663 unigenes were obtained in this study, with mean length 848.74 bp. 50,814, 49,584 and 49,814 unigenes were respectively obtained from FO, MO and HO groups. There were 2,343 differentially expressed genes between FO and MO, with 855 down- and 1,488 up-regulated genes in the MO group. 2,813 genes were differentially expressed between FO and HO, including 1,256 down- and 1,552 up-regulated genes in the HO group. 2,075 differentially expressed genes were found in the comparison of MO and HO, including 1,074 up- and 1,001 down-regulated genes in the MO group. Some differentially expressed genes, such as fatty acid transport protein (fatp), fatty acid binding protein (fabp), apolipoprotein (apo), peroxisome proliferator activated receptor-gamma (ppar-γ), acetyl-CoA synthetase (acs) and arachidonate 5-lipoxygenase (alox5), were involved in lipid metabolism, suggesting these genes in the loach were responsive to dietary oxidized fish oil. Results of transcriptome profilings here were validated using quantitative real time PCR in fourteen randomly selected unigenes. The present study provides insights into hepatic transcriptome profile of the loach, which is a valuable resource for studies of loach genomics. More importantly, this study identifies some important genes responsible for dietary oxidized fish oil, which will benefit researches of lipid metabolism in fish.

Highlights

MethodsAll experiments were conducted in strict accordance with the recommendations in the Guide for the Care and use of Laboratory Animals of Huazhong Agricultural University
There is a deficiency in desaturation and elongation pathways necessary for biosynthesis of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in fish [1]
In this paper we reported a hepatic transcriptome of loach Misgurnus anguillicaudatus, a small freshwater teleost that inhabits the muddy bottom of creeks, ponds, wetlands and paddy fields [26] and distributes widespreadly in China, Japan and other Southeast Asian countries [27], fed with three different diets, namely fresh fish oil diet (FO for short), medium oxidized fish oil diet (MO for short) and high oxidized fish oil diet (HO for short)

Summary

Methods

All experiments were conducted in strict accordance with the recommendations in the Guide for the Care and use of Laboratory Animals of Huazhong Agricultural University. This study was approved by the Institutional Animal Care and Use Ethics Committee of Huazhong Agricultural University. During the 12 weeks feeding trial, loaches’ health statuses were monitored thrice daily (8:00, 14:00 and 20:00 h), in accordance with the feeding time. Throughout the entire feeding trial, all the loaches were healthy, in other words, no weak and sick loaches or injured-loaches were found and they were all active. The method of euthanasia (i.e. decapitation) was used for loaches anesthetized with 100 mg/L tricaine methanesulfonate (MS-222). The loaches were placed on ice for tissues collections. All efforts were made to minimize loach suffering

Results

Discussion

Conclusion