Molecular cloning, tissue distribution and nutritional regulation of a Δ6-fatty acyl desaturase-like enzyme in large yellow croaker (Larimichthys crocea)

Abstract

In this study, the full-length cDNA of a D6-fatty acyl desaturase-like (D6-Fad-like) enzyme was first cloned from large yellow croaker, Larmichthys crocea. The cDNA was 2049 bp, with a 107 bp 5 0 -UTR, a 604 bp 3 0 -UTR, and an ORF of 1338 that specified a protein of 445 amino acids. It contains two membrane-spanning domains, three histidine-rich regions and a cytochrome b 5 domain, which all align perfectly with the same domains located in other recently identified vertebrate D5 and D6 desaturases. Sequence comparison showed that the predicted protein revealed a high percentage identity (>70%) with D6 desaturases from other marine fish species. Tissue distribution analysis revealed that D6-Fad-like was expressed at highest level in brain, much lower level in liver and gill, and lowest level in spleen, heart, stomach and intestine. The hepatic mRNA levels of D6-Fadlike showed statistically negative relationship relative to increasing dietary n-3LC-PUFA and DHA/ EPA (P < 0.05, R > 0.6). Transcription of D6-Fadlike in liver of fish fed diets with low and moderate level of n-3LC-PUFA (0.15%, 0.60% and 0.98% dry diet) was significantly increased by more than 20-fold than that with higher n-3LC-PUFA (1.37%, 1.79% and 2.25% dry diet; P < 0.05). The transcriptional levels of D6-Fad-like in the liver of fish fed diets with the ratio of 0.61, 1.54 and 2.17 (DHA/EPA) were significantly up-regulated by about 46-fold, 4.8-fold, and 1.2-fold compared with that in the control group (DHA/ EPA = 3.88) respectively (P < 0.05). This could contribute to better understanding the process of n-3LC-PUFA biosynthesis in this fish species.

Dietary DHA/EPA ratio affected tissue fatty acid profiles, antioxidant capacity, hematological characteristics and expression of lipid-related genes but not growth in juvenile black seabream (Acanthopagrus schlegelii)

“…In the present study, fish fed the lowest dietary DHA/EPA ratio (0.65) showed significantly higher expression of both fads2 and elovl5 . Consistently, the fads2 expression of large yellow croaker also increased with decreasing dietary DHA/EPA [69] and moreover, these results are in agreement with the effect that DHA had on down-regulating fads2 and elovl5 in rainbow trout ( Oncorhynchus mykiss ) [70]. However, the increased expression of fads2 and elovl5 observed in the present study for low DHA/EPA dietary treatments did not resulted in increased enzymatic activity to compensate for lower dietary input.…”

Functional characterization and differential nutritional regulation of putative Elovl5 and Elovl4 elongases in large yellow croaker (Larimichthys crocea)

“…Nutritional regulation of genes encoding desaturases and elongases has been proposed as a possible strategy to enhance the endogenous production on n-3 LC-PUFA and optimise their retention in farmed fish 8, 41, 42 . In general, n-3 LC-PUFA can suppress the transcription of the Elovl4 and Elovl5 encoding genes in fish 14–20 . Additionally, previous studies found that LC-PUFA and their metabolites can regulate transcription of lipid metabolism related genes through modulation of transcription factors including, among others, Lxrα and Srebp-1 24 .…”

Molecular cloning, tissue distribution and nutritional regulation of a fatty acylelovl5-likeelongase in large yellow croaker,Larimichthys crocea

“…However, as far as we know, little information was available about the molecular basis of LC‐PUFA biosynthesis in large yellow croaker. Recently, a Δ6‐fad‐like has been successfully cloned from large yellow croaker (Zuo, Mai, Xu, Dong & Ai ). Basic information about Fads and Elovl is not only of high relevance in advancing our understanding of molecular basis of LC‐PUFA biosynthesis and regulation in this fish but also provides possibility for applying transgenic technology in the future (Alimuddin, Yoshizaki, Kiron, Satoh & Takeuchi , ; Alimuddin, Kiron, Satoh, Takeuchi & Yoshizaki ; Kabeya, Takeuchi, Yamamoto, Yazawa, Haga, Satoh & Yoshizaki ).…”