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Oscar Monroig - One of the best experts on this subject based on the ideXlab platform.

  • biosynthesis of lc pufas and vlc pufas in pampus argenteus characterization of ELOVL4 elongases and regulation under acute salinity
    Journal of Agricultural and Food Chemistry, 2021
    Co-Authors: Jiaxiang Luo, Oscar Monroig, Kai Liao, Juan Carlos Navarro, Qicun Zhou, Alberto Ribesnavarro, Tingting Zhu, Liangli Xue, Min Jin
    Abstract:

    Salinity has been demonstrated to influence the biosynthesis of long-chain (C20-24) polyunsaturated fatty acids (LC-PUFAs) in teleost fish. Since LC-PUFAs are essential nutrients for vertebrates, it is central to understand how fish cope with an acute change in salinity associated with natural events. We herein report on the cloning and functional characterization of two elongation of very-long-chain fatty acid (Elovl)4 proteins, namely, ELOVL4a and ELOVL4b, and study the roles that these enzymes play in the biosynthesis of LC-PUFAs and very-long-chain (>C24) polyunsaturated fatty acids (VLC-PUFAs) in marine teleost Pampus argenteus. The P. argenteus ELOVL4 displayed all of the typical features of Elovl-like enzymes and have eyes and brain as major sites through which they exert their functions. Moreover, functional studies showed that the P. argenteus ELOVL4 can effectively elongate C18-22 substrates to C36 VLC-PUFA. Because both P. argenteus ELOVL4 are able to produce 24:5n - 3 from shorter precursors, we tested whether the previously reported Δ6 Fads2 from P. argenteus was able to desaturate 24:5n - 3 to 24:6n - 3, a key step for docosahexaenoic acid (DHA) synthesis. Our results showed that P. argenteus can indeed bioconvert 24:5n - 3 into 24:6n - 3, suggesting that P. argenteus has the enzymatic capacity required for DHA biosynthesis through the coordinated action of both ELOVL4 and Fads2. Furthermore, an acute salinity test indicated that low-salinity stress (12 ppt) upregulated genes involved in LC-PUFA biosynthesis, with 12 ppt salinity treatment showing the highest hepatic LC-PUFA content. Overall, our results unveiled that the newly characterized ELOVL4 enzymes have indispensable functions in LC- and VLC-PUFA biosynthesis. Moreover, acute salinity change influenced the biosynthesis of LC-PUFA in P. argenteus. This study provided new insight into the biosynthesis of LC- and VLC-PUFAs in vertebrates and the physiological responses that teleosts have under acute salinity stress.

  • nutritional regulation of genes responsible for long chain c20 24 and very long chain c24 polyunsaturated fatty acid biosynthesis in post larvae of gilthead seabream sparus aurata and senegalese sole solea senegalensis
    Aquaculture, 2020
    Co-Authors: Miguel Torres, Oscar Monroig, Juan Carlos Navarro, I Varo, Francisco Hontoria
    Abstract:

    Abstract The fatty acyl elongases ELOVL4 are pivotal components in the biosynthesis of very long-chain polyunsaturated fatty acids (VLC-PUFA) from long-chain polyunsaturated fatty acids (LC-PUFA). Thus, nutritional regulation of ELOVL4, as well as other elongase and desaturase genes involved in LC-PUFA biosynthesis (e.g., Elovl5, Fads2) has been proposed as a strategy to enhance endogenous production of LC-PUFA and VLC-PUFA under intensive farming conditions. This study aimed at investigating the nutritional regulation of genes involved in the biosynthesis of VLC-PUFA (ELOVL4 isoforms a and b) and LC-PUFA (fads2, elovl5) in Sparus aurata and Solea senegalensis post-larvae fed three inert micro-diets with graded concentrations of dietary LC-PUFA by using different combinations of fish oil and soya oil. The effect of dietary LC-PUFA on survival, growth and fatty acid composition was also examined. The results denoted that, while no effects were observed in survival, fish fed the diet with the highest LC-PUFA content during 30 d showed a higher total length and wet weight. Gene expression results showed that fads2, elovl5, ELOVL4a and ELOVL4b can be regulated by dietary LC-PUFA content. Remarkably, our results denoted a differential ELOVL4 nutritional regulation associated to each species. The head is the body part studied with the highest ELOVL4 transcripts in both fish species.

  • the fatty acid elongation genes ELOVL4a and ELOVL4b are present and functional in the genome of tambaqui colossoma macropomum
    Comparative Biochemistry and Physiology B, 2020
    Co-Authors: Renato Ferraz, Juan Carlos Navarro, Andre M Machado, Isabel Cunha, Rodrigo O A Ozorio, Ana Lucia Salaro, Filipe L C Castro, Oscar Monroig
    Abstract:

    Abstract Long-chain (C20–24) polyunsaturated fatty acids (LC-PUFA) are physiologically important nutrients for vertebrates including fish. Previous studies have addressed the metabolism of LC-PUFA in the Amazonian teleost tambaqui (Colossoma macropomum), an emerging species in Brazilian aquaculture, showing that all the desaturase and elongase activities required to convert C18 polyunsaturated fatty acids (PUFA) into LC-PUFA are present in tambaqui. Yet, elongation of very long-chain fatty acid 4 (ELOVL4) proteins, which participate in the biosynthesis of very long-chain (>C24) saturated fatty acids (VLC-SFA) and very long-chain polyunsaturated fatty acids (VLC-PUFA), had not been characterized in this species. Here, we investigate the repertoire and function of two ELOVL4 in tambaqui. Furthermore, we present the first draft genome assembly from tambaqui, and demonstrated the usefulness of this resource in nutritional physiology studies by isolating one of the tambaqui ELOVL4 genes. Our results showed that, similarly to other teleost species, two ELOVL4 gene paralogs termed as ELOVL4a and ELOVL4b, are present in tambaqui. Tambaqui ELOVL4a and ELOVL4b have open reading frames (ORF) of 948 and 912 base pairs, encoding putative proteins of 315 and 303 amino acids, respectively. Functional characterization in yeast showed that both ELOVL4 enzymes have activity toward all the PUFA substrates assayed (18:3n-3, 18:2n-6, 18:4n-3, 18:3n-6, 20:5n-3, 20:4n-6, 22:5n-3, 22:4n-6 and 22:6n-3), producing elongated products of up to C36. Moreover, both ELOVL4 were able to elongate 22:5n-3 to 24:5n-3, a key elongation step required for the synthesis of docosahexaenoic acid via the Sprecher pathway.

  • molecular and functional characterization of ELOVL4 genes in sparus aurata and solea senegalensis pointing to a critical role in very long chain c24 fatty acid synthesis during early neural development of fish
    International Journal of Molecular Sciences, 2020
    Co-Authors: Sofia Morais, Oscar Monroig, Francisco Hontoria, Miguel Torres, I Varo, Maria J Agulleiro, Juan Carlos Navarro
    Abstract:

    Very long-chain fatty acids (VLC-FA) play critical roles in neural tissues during the early development of vertebrates. However, studies on VLC-FA in fish are scarce. The biosynthesis of VLC-FA is mediated by elongation of very long-chain fatty acid 4 (ELOVL4) proteins and, consequently, the complement and activity of these enzymes determines the capacity that a given species has for satisfying its physiological demands, in particular for the correct development of neurophysiological functions. The present study aimed to characterize and localize the expression of ELOVL4 genes from Sparus aurata and Solea senegalensis, as well as to determine the function of their encoded proteins. The results confirmed that both fish possess two distinct ELOVL4 genes, named ELOVL4a and ELOVL4b. Functional assays demonstrated that both ELOVL4 isoforms had the capability to elongate long-chain (C20–24), both saturated (SFA) and polyunsaturated (PUFA), fatty acid precursors to VLC-FA. In spite of their overlapping activity, ELOVL4a was more active in VLC-SFA elongation, while ELOVL4b had a preponderant elongation activity towards n-3 PUFA substrates, particularly in S. aurata, being additionally the only isoform that is capable of elongating docosahexaenoic acid (DHA). A preferential expression of ELOVL4 genes was measured in neural tissues, being ELOVL4a and ELOVL4b mRNAs mostly found in brain and eyes, respectively.

  • expression of genes related to long chain c18 22 and very long chain c24 fatty acid biosynthesis in gilthead seabream sparus aurata and senegalese sole solea senegalensis larvae investigating early ontogeny and nutritional regulation
    Aquaculture, 2020
    Co-Authors: Miguel Torres, Oscar Monroig, Juan Carlos Navarro, I Varo, Sofia Morais, Maria J Agulleiro, Francisco Hontoria
    Abstract:

    Abstract Long-chain polyunsaturated fatty acids (LC-PUFA) have been extensively studied in aquaculture due to their importance for survival and development in teleosts. However, very long-chain polyunsaturated fatty acids (VLC-PUFA) have been practically unexplored within the aquaculture scenario. VLC-PUFA, although always present in small amounts, can be pivotal for the correct development and function of tissues such as retina, brain and gonads of vertebrates including fish. This study aimed at determining the temporal expression patterns of genes involved in the biosynthesis of VLC-PUFA (ELOVL4a, ELOVL4b) and their precursors, LC-PUFA, (fads2, elovl5) during the early ontogeny of Solea senegalensis and Sparus aurata. Furthermore, we investigated the nutritional regulation of these genes in early life-cycle stages of fish fed low and high LC-PUFA diets consisting of non-enriched and enriched live preys (Brachionus plicatilis and Artemia franciscana), respectively. The effect of dietary LC-PUFA on growth and fatty acid composition was also examined. The results obtained during early development reveal that all genes studied are expressed before the hatching stage. There is a consistency between the timing at which retinogenesis occurs in both species and an increase of the expression of the two ELOVL4 responsible for the synthesis of VLC-PUFA. The results obtained in nutritional assays for both species suggest that the expression of the two isoforms of ELOVL4 (isoform a in early larvae, and b in late larvae) can be regulated positively according to the dietary content of LC-PUFA in early stages, which could activate the VLC-PUFA biosynthesis even during short-term feeding periods (seven days). The body part analysis in late larvae of both species revealed that both isoforms of ELOVL4 are expressed preferentially in the head. This can be associated to their highest presence in the neural and visual tissues.

Juan Carlos Navarro - One of the best experts on this subject based on the ideXlab platform.

  • biosynthesis of lc pufas and vlc pufas in pampus argenteus characterization of ELOVL4 elongases and regulation under acute salinity
    Journal of Agricultural and Food Chemistry, 2021
    Co-Authors: Jiaxiang Luo, Oscar Monroig, Kai Liao, Juan Carlos Navarro, Qicun Zhou, Alberto Ribesnavarro, Tingting Zhu, Liangli Xue, Min Jin
    Abstract:

    Salinity has been demonstrated to influence the biosynthesis of long-chain (C20-24) polyunsaturated fatty acids (LC-PUFAs) in teleost fish. Since LC-PUFAs are essential nutrients for vertebrates, it is central to understand how fish cope with an acute change in salinity associated with natural events. We herein report on the cloning and functional characterization of two elongation of very-long-chain fatty acid (Elovl)4 proteins, namely, ELOVL4a and ELOVL4b, and study the roles that these enzymes play in the biosynthesis of LC-PUFAs and very-long-chain (>C24) polyunsaturated fatty acids (VLC-PUFAs) in marine teleost Pampus argenteus. The P. argenteus ELOVL4 displayed all of the typical features of Elovl-like enzymes and have eyes and brain as major sites through which they exert their functions. Moreover, functional studies showed that the P. argenteus ELOVL4 can effectively elongate C18-22 substrates to C36 VLC-PUFA. Because both P. argenteus ELOVL4 are able to produce 24:5n - 3 from shorter precursors, we tested whether the previously reported Δ6 Fads2 from P. argenteus was able to desaturate 24:5n - 3 to 24:6n - 3, a key step for docosahexaenoic acid (DHA) synthesis. Our results showed that P. argenteus can indeed bioconvert 24:5n - 3 into 24:6n - 3, suggesting that P. argenteus has the enzymatic capacity required for DHA biosynthesis through the coordinated action of both ELOVL4 and Fads2. Furthermore, an acute salinity test indicated that low-salinity stress (12 ppt) upregulated genes involved in LC-PUFA biosynthesis, with 12 ppt salinity treatment showing the highest hepatic LC-PUFA content. Overall, our results unveiled that the newly characterized ELOVL4 enzymes have indispensable functions in LC- and VLC-PUFA biosynthesis. Moreover, acute salinity change influenced the biosynthesis of LC-PUFA in P. argenteus. This study provided new insight into the biosynthesis of LC- and VLC-PUFAs in vertebrates and the physiological responses that teleosts have under acute salinity stress.

  • nutritional regulation of genes responsible for long chain c20 24 and very long chain c24 polyunsaturated fatty acid biosynthesis in post larvae of gilthead seabream sparus aurata and senegalese sole solea senegalensis
    Aquaculture, 2020
    Co-Authors: Miguel Torres, Oscar Monroig, Juan Carlos Navarro, I Varo, Francisco Hontoria
    Abstract:

    Abstract The fatty acyl elongases ELOVL4 are pivotal components in the biosynthesis of very long-chain polyunsaturated fatty acids (VLC-PUFA) from long-chain polyunsaturated fatty acids (LC-PUFA). Thus, nutritional regulation of ELOVL4, as well as other elongase and desaturase genes involved in LC-PUFA biosynthesis (e.g., Elovl5, Fads2) has been proposed as a strategy to enhance endogenous production of LC-PUFA and VLC-PUFA under intensive farming conditions. This study aimed at investigating the nutritional regulation of genes involved in the biosynthesis of VLC-PUFA (ELOVL4 isoforms a and b) and LC-PUFA (fads2, elovl5) in Sparus aurata and Solea senegalensis post-larvae fed three inert micro-diets with graded concentrations of dietary LC-PUFA by using different combinations of fish oil and soya oil. The effect of dietary LC-PUFA on survival, growth and fatty acid composition was also examined. The results denoted that, while no effects were observed in survival, fish fed the diet with the highest LC-PUFA content during 30 d showed a higher total length and wet weight. Gene expression results showed that fads2, elovl5, ELOVL4a and ELOVL4b can be regulated by dietary LC-PUFA content. Remarkably, our results denoted a differential ELOVL4 nutritional regulation associated to each species. The head is the body part studied with the highest ELOVL4 transcripts in both fish species.

  • the fatty acid elongation genes ELOVL4a and ELOVL4b are present and functional in the genome of tambaqui colossoma macropomum
    Comparative Biochemistry and Physiology B, 2020
    Co-Authors: Renato Ferraz, Juan Carlos Navarro, Andre M Machado, Isabel Cunha, Rodrigo O A Ozorio, Ana Lucia Salaro, Filipe L C Castro, Oscar Monroig
    Abstract:

    Abstract Long-chain (C20–24) polyunsaturated fatty acids (LC-PUFA) are physiologically important nutrients for vertebrates including fish. Previous studies have addressed the metabolism of LC-PUFA in the Amazonian teleost tambaqui (Colossoma macropomum), an emerging species in Brazilian aquaculture, showing that all the desaturase and elongase activities required to convert C18 polyunsaturated fatty acids (PUFA) into LC-PUFA are present in tambaqui. Yet, elongation of very long-chain fatty acid 4 (ELOVL4) proteins, which participate in the biosynthesis of very long-chain (>C24) saturated fatty acids (VLC-SFA) and very long-chain polyunsaturated fatty acids (VLC-PUFA), had not been characterized in this species. Here, we investigate the repertoire and function of two ELOVL4 in tambaqui. Furthermore, we present the first draft genome assembly from tambaqui, and demonstrated the usefulness of this resource in nutritional physiology studies by isolating one of the tambaqui ELOVL4 genes. Our results showed that, similarly to other teleost species, two ELOVL4 gene paralogs termed as ELOVL4a and ELOVL4b, are present in tambaqui. Tambaqui ELOVL4a and ELOVL4b have open reading frames (ORF) of 948 and 912 base pairs, encoding putative proteins of 315 and 303 amino acids, respectively. Functional characterization in yeast showed that both ELOVL4 enzymes have activity toward all the PUFA substrates assayed (18:3n-3, 18:2n-6, 18:4n-3, 18:3n-6, 20:5n-3, 20:4n-6, 22:5n-3, 22:4n-6 and 22:6n-3), producing elongated products of up to C36. Moreover, both ELOVL4 were able to elongate 22:5n-3 to 24:5n-3, a key elongation step required for the synthesis of docosahexaenoic acid via the Sprecher pathway.

  • molecular and functional characterization of ELOVL4 genes in sparus aurata and solea senegalensis pointing to a critical role in very long chain c24 fatty acid synthesis during early neural development of fish
    International Journal of Molecular Sciences, 2020
    Co-Authors: Sofia Morais, Oscar Monroig, Francisco Hontoria, Miguel Torres, I Varo, Maria J Agulleiro, Juan Carlos Navarro
    Abstract:

    Very long-chain fatty acids (VLC-FA) play critical roles in neural tissues during the early development of vertebrates. However, studies on VLC-FA in fish are scarce. The biosynthesis of VLC-FA is mediated by elongation of very long-chain fatty acid 4 (ELOVL4) proteins and, consequently, the complement and activity of these enzymes determines the capacity that a given species has for satisfying its physiological demands, in particular for the correct development of neurophysiological functions. The present study aimed to characterize and localize the expression of ELOVL4 genes from Sparus aurata and Solea senegalensis, as well as to determine the function of their encoded proteins. The results confirmed that both fish possess two distinct ELOVL4 genes, named ELOVL4a and ELOVL4b. Functional assays demonstrated that both ELOVL4 isoforms had the capability to elongate long-chain (C20–24), both saturated (SFA) and polyunsaturated (PUFA), fatty acid precursors to VLC-FA. In spite of their overlapping activity, ELOVL4a was more active in VLC-SFA elongation, while ELOVL4b had a preponderant elongation activity towards n-3 PUFA substrates, particularly in S. aurata, being additionally the only isoform that is capable of elongating docosahexaenoic acid (DHA). A preferential expression of ELOVL4 genes was measured in neural tissues, being ELOVL4a and ELOVL4b mRNAs mostly found in brain and eyes, respectively.

  • expression of genes related to long chain c18 22 and very long chain c24 fatty acid biosynthesis in gilthead seabream sparus aurata and senegalese sole solea senegalensis larvae investigating early ontogeny and nutritional regulation
    Aquaculture, 2020
    Co-Authors: Miguel Torres, Oscar Monroig, Juan Carlos Navarro, I Varo, Sofia Morais, Maria J Agulleiro, Francisco Hontoria
    Abstract:

    Abstract Long-chain polyunsaturated fatty acids (LC-PUFA) have been extensively studied in aquaculture due to their importance for survival and development in teleosts. However, very long-chain polyunsaturated fatty acids (VLC-PUFA) have been practically unexplored within the aquaculture scenario. VLC-PUFA, although always present in small amounts, can be pivotal for the correct development and function of tissues such as retina, brain and gonads of vertebrates including fish. This study aimed at determining the temporal expression patterns of genes involved in the biosynthesis of VLC-PUFA (ELOVL4a, ELOVL4b) and their precursors, LC-PUFA, (fads2, elovl5) during the early ontogeny of Solea senegalensis and Sparus aurata. Furthermore, we investigated the nutritional regulation of these genes in early life-cycle stages of fish fed low and high LC-PUFA diets consisting of non-enriched and enriched live preys (Brachionus plicatilis and Artemia franciscana), respectively. The effect of dietary LC-PUFA on growth and fatty acid composition was also examined. The results obtained during early development reveal that all genes studied are expressed before the hatching stage. There is a consistency between the timing at which retinogenesis occurs in both species and an increase of the expression of the two ELOVL4 responsible for the synthesis of VLC-PUFA. The results obtained in nutritional assays for both species suggest that the expression of the two isoforms of ELOVL4 (isoform a in early larvae, and b in late larvae) can be regulated positively according to the dietary content of LC-PUFA in early stages, which could activate the VLC-PUFA biosynthesis even during short-term feeding periods (seven days). The body part analysis in late larvae of both species revealed that both isoforms of ELOVL4 are expressed preferentially in the head. This can be associated to their highest presence in the neural and visual tissues.

Douglas R Tocher - One of the best experts on this subject based on the ideXlab platform.

  • genome wide identification and functional characterization of two lc pufa biosynthesis elongase elovl8 genes in rabbitfish siganus canaliculatus
    Aquaculture, 2020
    Co-Authors: Zhengyong Wen, Douglas R Tocher, Cuihong You, Zhiyong Xie, Yueling Zhang, Shuqi Wang
    Abstract:

    Abstract Elongases of very long-chain fatty acids (Elovls) catalyze the rate-limiting step of the elongation pathway that results in net two‑carbon elongation of pre-existing fatty acyl chains. As a set of crucial enzymes involved in the long-chain polyunsaturated fatty acids (LC-PUFA) biosynthesis, Elovls of fish have been investigated extensively in recent years. In the present study, we first identified two novel fish-specific elovl genes (named as elovl8a and elovl8b) from the herbivorous marine teleost rabbitfish (Siganus canaliculatus) by genomic survey and molecular cloning methods. Subsequently, their functional characteristics, tissue distribution patterns and transcriptional changes in response to different nutritional states were investigated. Full-length coding sequences of the elovl8a and elovl8b genes were 804 and 792 bp, encoding 267 and 263 amino acids, respectively. Multiple alignment, genomic synteny and phylogenetic analyses further suggested that elovl8 genes were unique to teleosts. Functional characterization by heterologous expression in yeast showed that Elovl8b could elongate C18 (18:2n-6, 18:3n-3 and 18:4n-3) and C20 (20:4n-6 and 20:5n-3) polyunsaturated fatty acids (PUFAs) to longer-chain polyunsaturated fatty acids (LC-PUFAs) whereas Elovl8a lacked this ability. In vitro, the expression of elovl8b but not elovl8a in rabbitfish hepatocytes was significantly up-regulated by incubation with 18:2n-6, 18:3n-3, 20:4n-6 and 20:5n-3, respectively. In vivo, compared with fish oil, dietary vegetable oil enriched in C18 PUFA enhanced the expression of elovl8b in rabbitfish brain, liver, intestine and gill tissues. These findings suggest that elovl8b but not elovl8a is a novel active member of the Elovl protein family involved in the LC-PUFAs biosynthesis pathway in rabbitfish, and provide novel insight into the mechanisms of LC-PUFAs biosynthesis in teleost.

  • molecular and functional characterisation of a putative ELOVL4 gene and its expression in response to dietary fatty acid profile in atlantic bluefin tuna thunnus thynnus
    Comparative Biochemistry and Physiology B, 2020
    Co-Authors: Monica B Betancor, Douglas R Tocher, Angela Oboh, Juan Carlos Navarro, Aurelio Ortega, Gabriel Mourente, Fernando De La Gandara, Oscar Monroig
    Abstract:

    Elongation of very long-chain fatty acid 4 (ELOVL4) proteins are involved in the biosynthesis of very long-chain (>C24) fatty acids and in many teleost fish species they are key enzymes in the pathway for the production of docosahexaenoic acid (DHA; 22:6n-3) from eicosapentaenoic acid (EPA; 20:5n-3). Therefore, ELOVL4 may be particularly important in Atlantic bluefin tuna (ABT; Thunnus thynnus) characterised by having high DHA to EPA ratios. The present study cloned and characterised both the function and expression of an ELOVL4 cDNA from ABT. The ELOVL4 had an open reading frame of 915 base pairs encoding a putative protein of 304 amino acids. Alignment and phylogenetic analyses indicated that the ELOVL4 isoform identified in the present study was an ELOVL4b. Functional characterisation demonstrated that the ELOVL4b enzyme had elongase activity towards all the polyunsaturated fatty acid (PUFA) substrates assayed. The ABT ELOVL4b contributed to DHA biosynthesis by elongation of EPA and DPA to 24:5n-3, the latter being desaturated to 24:6n-3 by the action of fads2 (Δ6 desaturase). Additionally, the ABT ELOVL4b has a role in the biosynthesis of very long-chain PUFA up to C34, compounds of key structural roles in neural tissues such as eye and brain, which had high levels of ELOVL4b transcripts. Surprisingly, while the relative expression of fads2, required for the production of DHA from EPA, was increased in liver of ABT fed a diet with reduced levels of EPA and DHA, expression of ELOVL4b was reduced. Results indicated that ABT has enzymes necessary for endogenous production of DHA from EPA and demonstrate that ELOVL4b can effectively compensate for absence of Elovl2.

  • biosynthesis of long chain polyunsaturated fatty acids in the razor clam sinonovacula constricta characterization of four fatty acyl elongases and a novel desaturase capacity
    Biochimica et Biophysica Acta, 2019
    Co-Authors: Jilin Xu, Angela Oboh, Oscar Monroig, Kai Liao, Juan Carlos Navarro, Qicun Zhou, Chengxu Zhou, Douglas R Tocher
    Abstract:

    Abstract As an unusual economically important aquaculture species, Sinonovacula constricta possesses high levels of long-chain polyunsaturated fatty acids (LC-PUFA). Previously, our group identified fatty acyl desaturases (Fad) with Δ5 and Δ6 activities in S. constricta, which was the first report of Δ6 Fad in a marine mollusc. Here, we further successfully characterize elongases of very long-chain fatty acids (Elovl) in this important bivalve species, including one Elovl2/5, two ELOVL4 isoforms (a and b) and a novel Elovl (c) with ELOVL4 activity. In addition, we also determined the desaturation activity of S. constricta Δ6 Fad toward 24:5n-3 to give 24:6n-3, a key intermediate in docosahexaenoic acid (DHA) biosynthesis. Therefore, S. constricta is the first marine mollusc reported to possess all Fad and Elovl activities required for LC-PUFA biosynthesis via the ‘Sprecher pathway’. This finding greatly increases our understanding of LC-PUFA biosynthesis in marine molluscs. Phylogenetic analysis by interrogating six marine molluscan genomes, and previously functionally characterized Elovl and Fad from marine molluscs, suggested that DHA biosynthetic ability was limited to a few species, due to the general lack of Δ4 or Δ6 Fad in most molluscs.

  • essential fatty acid metabolism and requirements of the cleaner fish ballan wrasse labrus bergylta defining pathways of long chain polyunsaturated fatty acid biosynthesis
    Aquaculture, 2018
    Co-Authors: Douglas R Tocher, Naoki Kabeya, Simon Yevzelman, Angela Oboh, Oscar Monroig
    Abstract:

    Abstract Ballan wrasse ( Labrus bergylta ) is an effective counter-measure against sea lice used by Atlantic salmon farmers, proving to be more effective and economical than drugs or chemical treatments alone. There are currently efforts underway to establish a robust culture system for this species, however, essential fatty acid dietary requirements are not known for ballan wrasse. In the present study, we isolated and functionally characterised ballan wrasse fatty acid desaturase (Fads) and elongation of very long-chain fatty acids (Elovl) protein to elucidate their long-chain polyunsaturated fatty acid (LC-PUFA) biosynthetic capability. Sequence and phylogenetic analysis demonstrated that the cloned genes were fads2 and elovl5 orthologues of other teleost species. Functional characterisations of fads2 and elovl5 were performed using the yeast ( Saccharomyces cerevisiae ) heterologous expression system. The Fads2 showed Δ6 desaturase activity towards 18:3n–3, 18:2n–6 and 24:5n–3, and Δ8 desaturase activity towards 20:3n–6 and 20:2n–6. The Elovl5 showed elongase activities towards various C 18 and C 20 fatty acids. Therefore, 20:4n–3 and 20:3n–6 can be synthesised from 18:3n–3 and 18:2n–6, respectively in ballan wrasse via two possible pathways, the Δ6 (Δ6 desaturation – elongation) and Δ8 (elongation – Δ8 desaturation) pathways. However, due to the absence of Δ5 desaturase activity and no other Fads2 in their genome, 20:5n–3 (eicosapentaenoic acid, EPA) and 20:4n–6 (arachidonic acid, ARA) cannot be synthesised from C 18 PUFA precursors and they could consequently be regarded as dietary essential fatty acids for ballan wrasse. Since no Δ4 desaturase activity was detected in ballan wrasse Fads2, 22:6n–3 (docosahexaenoic acid, DHA) can only be synthesised from EPA via the Sprecher pathway comprising two sequential elongation steps to produce 24:5n–3 followed by Δ6 desaturation and chain shortening. Although ballan wrasse Elovl5 had no elongase activity towards C 22 , other elongases such as ELOVL4 exist in the ballan wrasse genome that may be able to produce 24:5n–3. Therefore, as ballan wrasse Fads2 can desaturate 24:5n–3 to produce 24:6n-3, it can be assumed that ballan wrasse can synthesise DHA from EPA.

  • molecular and functional characterisation of two ELOVL4 elongases involved in the biosynthesis of very long chain c24 polyunsaturated fatty acids in black seabream acanthopagrus schlegelii
    Comparative Biochemistry and Physiology B, 2017
    Co-Authors: Douglas R Tocher, Oscar Monroig, Juan Carlos Navarro, Min Jin, Qicun Zhou
    Abstract:

    Abstract Elongation of very long-chain fatty acid (Elovl) 4 proteins are important fatty acyl elongases that participate in the biosynthesis of long-chain (C 20–24 ) and very long-chain (˃C 24 ) polyunsaturated fatty acids (LC-PUFA and VLC-PUFA, respectively) in teleost fish, especially in marine species. Moreover, knowledge of ELOVL4 and other elongases such as Elovl2 has contributed to an advanced understanding of the LC-PUFA biosynthetic pathway in marine fish. In the present study, ELOVL4a and ELOVL4b were cloned from black seabream Acanthopagrus schlegelii and functionally characterised using recombinant expression in yeast. The ELOVL4a and ELOVL4b cDNA sequences included open reading frames (ORF) of 969 and 918 base pairs (bp), encoding proteins of 322 and 315 amino acids (aa), respectively. The functional characterisation of A . schlegelii ELOVL4 proteins showed they were able to utilise all assayed C 18–22 PUFA substrates except 22:6n − 3. Moreover, it was particularly noteworthy that both A . schlegelii ELOVL4a and ELOVL4b proteins had the ability to elongate 20:5n − 3 and 22:5n − 3 to 24:5n − 3, which can be potentially desaturated and β -oxidised to 22:6n − 3. Tissue transcript abundance analysis showed the highest expression of ELOVL4a and ELOVL4b in brain and eye, respectively, suggesting these tissues were major sites for VLC-PUFA biosynthesis in black seabream. The functions of the A . schlegelii ELOVL4-like elongases, ELOVL4a and ELOVL4b, characterised in the present study, along with those of the Elovl5 and fatty acyl desaturase (Fads2) proteins of A . schlegelii characterised previously, provided evidence of the biosynthetic pathways of LC-PUFA and VLC-PUFA in this teleost species.

Francisco Hontoria - One of the best experts on this subject based on the ideXlab platform.

  • nutritional regulation of genes responsible for long chain c20 24 and very long chain c24 polyunsaturated fatty acid biosynthesis in post larvae of gilthead seabream sparus aurata and senegalese sole solea senegalensis
    Aquaculture, 2020
    Co-Authors: Miguel Torres, Oscar Monroig, Juan Carlos Navarro, I Varo, Francisco Hontoria
    Abstract:

    Abstract The fatty acyl elongases ELOVL4 are pivotal components in the biosynthesis of very long-chain polyunsaturated fatty acids (VLC-PUFA) from long-chain polyunsaturated fatty acids (LC-PUFA). Thus, nutritional regulation of ELOVL4, as well as other elongase and desaturase genes involved in LC-PUFA biosynthesis (e.g., Elovl5, Fads2) has been proposed as a strategy to enhance endogenous production of LC-PUFA and VLC-PUFA under intensive farming conditions. This study aimed at investigating the nutritional regulation of genes involved in the biosynthesis of VLC-PUFA (ELOVL4 isoforms a and b) and LC-PUFA (fads2, elovl5) in Sparus aurata and Solea senegalensis post-larvae fed three inert micro-diets with graded concentrations of dietary LC-PUFA by using different combinations of fish oil and soya oil. The effect of dietary LC-PUFA on survival, growth and fatty acid composition was also examined. The results denoted that, while no effects were observed in survival, fish fed the diet with the highest LC-PUFA content during 30 d showed a higher total length and wet weight. Gene expression results showed that fads2, elovl5, ELOVL4a and ELOVL4b can be regulated by dietary LC-PUFA content. Remarkably, our results denoted a differential ELOVL4 nutritional regulation associated to each species. The head is the body part studied with the highest ELOVL4 transcripts in both fish species.

  • molecular and functional characterization of ELOVL4 genes in sparus aurata and solea senegalensis pointing to a critical role in very long chain c24 fatty acid synthesis during early neural development of fish
    International Journal of Molecular Sciences, 2020
    Co-Authors: Sofia Morais, Oscar Monroig, Francisco Hontoria, Miguel Torres, I Varo, Maria J Agulleiro, Juan Carlos Navarro
    Abstract:

    Very long-chain fatty acids (VLC-FA) play critical roles in neural tissues during the early development of vertebrates. However, studies on VLC-FA in fish are scarce. The biosynthesis of VLC-FA is mediated by elongation of very long-chain fatty acid 4 (ELOVL4) proteins and, consequently, the complement and activity of these enzymes determines the capacity that a given species has for satisfying its physiological demands, in particular for the correct development of neurophysiological functions. The present study aimed to characterize and localize the expression of ELOVL4 genes from Sparus aurata and Solea senegalensis, as well as to determine the function of their encoded proteins. The results confirmed that both fish possess two distinct ELOVL4 genes, named ELOVL4a and ELOVL4b. Functional assays demonstrated that both ELOVL4 isoforms had the capability to elongate long-chain (C20–24), both saturated (SFA) and polyunsaturated (PUFA), fatty acid precursors to VLC-FA. In spite of their overlapping activity, ELOVL4a was more active in VLC-SFA elongation, while ELOVL4b had a preponderant elongation activity towards n-3 PUFA substrates, particularly in S. aurata, being additionally the only isoform that is capable of elongating docosahexaenoic acid (DHA). A preferential expression of ELOVL4 genes was measured in neural tissues, being ELOVL4a and ELOVL4b mRNAs mostly found in brain and eyes, respectively.

  • expression of genes related to long chain c18 22 and very long chain c24 fatty acid biosynthesis in gilthead seabream sparus aurata and senegalese sole solea senegalensis larvae investigating early ontogeny and nutritional regulation
    Aquaculture, 2020
    Co-Authors: Miguel Torres, Oscar Monroig, Juan Carlos Navarro, I Varo, Sofia Morais, Maria J Agulleiro, Francisco Hontoria
    Abstract:

    Abstract Long-chain polyunsaturated fatty acids (LC-PUFA) have been extensively studied in aquaculture due to their importance for survival and development in teleosts. However, very long-chain polyunsaturated fatty acids (VLC-PUFA) have been practically unexplored within the aquaculture scenario. VLC-PUFA, although always present in small amounts, can be pivotal for the correct development and function of tissues such as retina, brain and gonads of vertebrates including fish. This study aimed at determining the temporal expression patterns of genes involved in the biosynthesis of VLC-PUFA (ELOVL4a, ELOVL4b) and their precursors, LC-PUFA, (fads2, elovl5) during the early ontogeny of Solea senegalensis and Sparus aurata. Furthermore, we investigated the nutritional regulation of these genes in early life-cycle stages of fish fed low and high LC-PUFA diets consisting of non-enriched and enriched live preys (Brachionus plicatilis and Artemia franciscana), respectively. The effect of dietary LC-PUFA on growth and fatty acid composition was also examined. The results obtained during early development reveal that all genes studied are expressed before the hatching stage. There is a consistency between the timing at which retinogenesis occurs in both species and an increase of the expression of the two ELOVL4 responsible for the synthesis of VLC-PUFA. The results obtained in nutritional assays for both species suggest that the expression of the two isoforms of ELOVL4 (isoform a in early larvae, and b in late larvae) can be regulated positively according to the dietary content of LC-PUFA in early stages, which could activate the VLC-PUFA biosynthesis even during short-term feeding periods (seven days). The body part analysis in late larvae of both species revealed that both isoforms of ELOVL4 are expressed preferentially in the head. This can be associated to their highest presence in the neural and visual tissues.

  • functional characterization and differential nutritional regulation of putative elovl5 and ELOVL4 elongases in large yellow croaker larimichthys crocea
    Scientific Reports, 2017
    Co-Authors: Oscar Monroig, Douglas R Tocher, Kai Liao, Juan Carlos Navarro, Francisco Hontoria, Tianjiao Wang, Yuhui Yuan, Kangsen Mai
    Abstract:

    In the present study, two elongases, ELOVL4 and Elovl5, were functionally characterized and their transcriptional regulation in response to n-3 LC-PUFA administration were investigated in vivo and in vitro. We previously described the molecular characterization of croaker elovl5. Here, we report the full-length cDNA sequence of croaker ELOVL4, which contained 1794 bp (excluding the polyA tail), including 909 bp of coding region that encoded a polypeptide of 302 amino acids possessing all the characteristic features of Elovl proteins. Functional studies showed that croaker Elovl5, displayed high elongation activity towards C18 and C20 PUFA, with only low activity towards C22 PUFA. In contrast, croaker ELOVL4 could effectively convert both C20 and C22 PUFA to longer polyenoic products up to C34. n-3 LC-PUFA suppressed transcription of the two elongase genes, as well as srebp-1 and lxrα, major regulators of hepatic lipid metabolism. The results of dual-luciferase reporter assays and in vitro studies both indicated that the transcriptions of elovl5 and ELOVL4 elongases could be regulated by Lxrα. Moreover, Lxrα could mediate the transcription of ELOVL4 directly or indirectly through regulating the transcription of srebp-1. The above findings contribute further insight and understanding of the mechanisms regulating LC-PUFA biosynthesis in marine fish species.

  • biosynthesis of essential fatty acids in octopus vulgaris cuvier 1797 molecular cloning functional characterisation and tissue distribution of a fatty acyl elongase
    Aquaculture, 2012
    Co-Authors: Oscar Monroig, Douglas R Tocher, Diana Guinot, Francisco Hontoria, Juan Carlos Navarro
    Abstract:

    Polyunsaturated fatty acids (PUFAs) have been identified as key nutrients for the common octopus (Octopus vulgaris), particularly for its early life-cycle stages (paralarvae). Our overarching aim is to identify the dietary essential fatty acid (FA) for octopus paralarvae through characterisation of the enzymes of endogenous PUFA biosynthetic pathways. Here we report on the molecular cloning and functional characterisation of a cDNA encoding a putative elongase of very long-chain fatty acids (Elovl), a critical enzyme that catalyses the elongation of FA including PUFA. Our results suggest that the octopus Elovl is phylogenetically related to Elovl5 and Elovl2, two elongases with demonstrated roles in PUFA biosynthesis in vertebrates. Further evidence supporting a role of the octopus Elovl in PUFA biosynthesis was provided through functional characterisation of its activity in yeast. It was confirmed that expression of the octopus Elovl conferred on yeast the ability to elongate some C18 and C20 PUFAs, while C22 PUFA substrates remained unmodified. Therefore, the substrate specificities exhibited by the octopus elongase were consistent with those of vertebrate Elovl5. Interestingly, the octopus Elovl elongated n − 6 PUFA substrates more efficiently than their homologous n − 3 substrates, suggesting that n − 6 PUFA may have particular biological significance in O. vulgaris. Finally, we investigated the potential role of the newly cloned Elovl in the biosynthesis of non-methylene-interrupted FA, compounds typically found in marine invertebrates and confirmed to be also present in the common octopus.

Monroig Óscar - One of the best experts on this subject based on the ideXlab platform.

  • Biosynthesis of LC-PUFA and VLC-PUFA in Pampus argenteus: Characterization of ELOVL4 elongases and regulation under acute salinity
    'American Chemical Society (ACS)', 2021
    Co-Authors: Luo Jiaxiang, Monroig Óscar, Ribes Alberto, Navarro, Juan Carlos, Liao Kai, Zhu Tingting, Li Juan
    Abstract:

    Salinity has been demonstrated to influence the biosynthesis of long-chain (C20–24) polyunsaturated fatty acids (LC-PUFAs) in teleost fish. Since LC-PUFAs are essential nutrients for vertebrates, it is central to understand how fish cope with an acute change in salinity associated with natural events. We herein report on the cloning and functional characterization of two elongation of very-long-chain fatty acid (Elovl)4 proteins, namely, ELOVL4a and ELOVL4b, and study the roles that these enzymes play in the biosynthesis of LC-PUFAs and very-long-chain (>C24) polyunsaturated fatty acids (VLC-PUFAs) in marine teleost Pampus argenteus. The P. argenteus ELOVL4 displayed all of the typical features of Elovl-like enzymes and have eyes and brain as major sites through which they exert their functions. Moreover, functional studies showed that the P. argenteus ELOVL4 can effectively elongate C18–22 substrates to C36 VLC-PUFA. Because both P. argenteus ELOVL4 are able to produce 24:5n – 3 from shorter precursors, we tested whether the previously reported Δ6 Fads2 from P. argenteus was able to desaturate 24:5n – 3 to 24:6n – 3, a key step for docosahexaenoic acid (DHA) synthesis. Our results showed that P. argenteus can indeed bioconvert 24:5n – 3 into 24:6n – 3, suggesting that P. argenteus has the enzymatic capacity required for DHA biosynthesis through the coordinated action of both ELOVL4 and Fads2. Furthermore, an acute salinity test indicated that low-salinity stress (12 ppt) upregulated genes involved in LC-PUFA biosynthesis, with 12 ppt salinity treatment showing the highest hepatic LC-PUFA content. Overall, our results unveiled that the newly characterized ELOVL4 enzymes have indispensable functions in LC- and VLC-PUFA biosynthesis. Moreover, acute salinity change influenced the biosynthesis of LC-PUFA in P. argenteus. This study provided new insight into the biosynthesis of LC- and VLC-PUFAs in vertebrates and the physiological responses that teleosts have under acute salinity stress.This study was supported by the National Key R&D Program of China (2018YFD0900400), the Nature Science Foundation of Zhejiang Province (LY17C190002 and Y21C190016), the National Natural Science Foundation of China (31802303 and 32072987), Key Research Program of Zhejiang Province of China (2018C02037), Ningbo Agricultural Major Project (2015C110003), Zhejiang Major Science Project (2019C02059), Natural Science Foundation of Zhejiang Province (LQ20C190005), Natural Science Foundation of Ningbo (2019A610427), and the Industrial Chain Collaborative Innovation Project of the Demonstration Work on Innovative Development of the Marine Economy of the State Oceanic Administration (NBHY-2017-S2). This research was also sponsored by the K. C. Wong Magna Fund from Ningbo University. Further funding was obtained through a Proyecto Intramural Especial of CSIC (201840I016) awarded to Ó .M

  • Biosynthesis of Long-Chain Polyunsaturated Fatty Acids in Marine Gammarids: Molecular Cloning and Functional Characterisation of Three Fatty Acyl Elongases
    'MDPI AG', 2021
    Co-Authors: Ribes Alberto, Kabeya Naoki, Navarro, Juan Carlos, Hontoria Francisco, Standal, Inger B., Evjemo, Jan O., Monroig Óscar
    Abstract:

    © 2021 by the authors.Long-chain (C20–24) polyunsaturated fatty acids (LC-PUFAs) are essential nutrients that are mostly produced in marine ecosystems. Previous studies suggested that gammarids have some capacity to endogenously produce LC-PUFAs. This study aimed to investigate the repertoire and functions of elongation of very long-chain fatty acid (Elovl) proteins in gammarids. Our results show that gammarids have, at least, three distinct elovl genes with putative roles in LC-PUFA biosynthesis. Phylogenetics allowed us to classify two elongases as ELOVL4 and Elovl6, as they were bona fide orthologues of vertebrate ELOVL4 and Elovl6. Moreover, a third elongase was named as “Elovl1/7-like” since it grouped closely to the Elovl1 and Elovl7 found in vertebrates. Molecular analysis of the deduced protein sequences indicated that the gammarid ELOVL4 and Elovl1/7-like were indeed polyunsaturated fatty acid (PUFA) elongases, whereas Elovl6 had molecular features typically found in non-PUFA elongases. This was partly confirmed in the functional assays performed on the marine gammarid Echinogammarus marinus Elovl, which showed that both ELOVL4 and Elovl1/7-like elongated PUFA substrates ranging from C18 to C22. E. marinus Elovl6 was only able to elongate C18 PUFA substrates, suggesting that this enzyme does not play major roles in the LC-PUFA biosynthesis of gammarids. View Full-TextThis study was funded through the project IMPROMEGA of the Ministry of Science, Innovation and Universities, Spanish Government (RTI2018-095119-B-100, MCIU/AEI/FEDER/UE), and the project “Recycling of rest raw materials from bio-based industry by production of low trophic Crustaceans (Gammaridae) for new marine ingredients (BioCycles)” financed by The Research Council of Norway (295063).Peer reviewe

  • Physiological roles of very long-chain (>C24) fatty acids during early development of fish: molecular and functional characterization of ELOVL4 genes in Sparus aurata and Solea senegalensis
    'Japanese Society of Applied Entomology & Zoology', 2021
    Co-Authors: Torres M., Monroig Óscar, Hontoria Francisco, Varó Inmaculada, Morais Sofia, Agulleiro Gozalbo, Maria Josep, Navarro, Juan Carlos
    Abstract:

    Resumen del trabajo presentado en el VII International Symposium on Marine Science, celebrado en Barcelona (España) del 1 al 3 de julio de 2020.Very long-chain (˃C24) fatty acids (VLC-FA) play critical roles during early development of vertebrates, since these compounds are accumulated in the rapidly forming neural tissues, ensuring their normal function. However, despite their putative importance, the study of VLC-FA in fish is scarce. Biosynthesis of VLC-FA is carried out by the socalled elongation of very long-chain fatty acid 4 (ELOVL4) proteins and, consequently, the complement and function of these enzymes determine the capacity that a given species has for satisfying the physiological demands for VLC-FA, especially during its early development [1,2]. The present study aimed to characterize ELOVL4 genes from the marine teleosts Sparus aurata and Solea senegalensis, and determine the function of the corresponding encoded proteins. Moreover, the tissue expression pattern of ELOVL4 genes was determined. The results confirmed that both fish species possess two distinct ELOVL4 proteins termed as ELOVL4a and ELOVL4b based on their homology to the zebrafish orthologs [3]. Functional assays in yeast denoted that both ELOVL4a and ELOVL4b from both species had the capability to elongate C20-24 fatty acid precursors to VLC-FA products. However, ELOVL4b appeared to have a higher activity than ELOVL4a elongating all the polyunsaturated fatty acid substrates assayed to longer chain polyunsaturated products, especially on the n3 series. Gene expression results indicated that, although ELOVL4 transcripts were detected in most tissues analyzed, ELOVL4 genes were more strongly expressed in both species neural tissues such as brain and eyes, which showed the highest expression levels of ELOVL4a and ELOVL4b, respectively. These results are consistent with the functions of ELOVL4 from other vertebrates. Importantly, these findings contribute to a better understanding of the VLCFA biosynthetic pathway in marine teleosts, highlighting the crucial role that ELOVL4 products carry out for the correct development and maintenance of neurophysiologic functions during early stages of the fish development.This research was funded by the projects AGL 2013-40986-R (Spanish Government, Ministry of Economy and Competitiveness), and PROMETEO II / 2014/085 (Generalitat Valenciana). Miguel Torres was supported by a PhD funding program from Diputación de Castellón

  • Tissue‐expression pattern of ELOVL4 genes in Sparus aurata and Solea senegalensis: from larvae to adult
    'Japanese Society of Applied Entomology & Zoology', 2021
    Co-Authors: Torres M., Monroig Óscar, Hontoria Francisco, Varó Inmaculada, Navarro, Juan Carlos
    Abstract:

    Póster presentado en el X Foro Iberoamericano de los Recursos Marinos y la Acuicultura, celebrado en modalidad virtual del 7 al 12 de febrero de 2021.[Introduction]: Very long‐chain (˃C24) fatty acids (VLC‐FA) play critical roles during early development of vertebrates. However, studies on VLC‐FA in fish are scarce. The biosynthesis of VLC‐FA is mediated by ELOVL4 proteins. Such ability is itself dependent on the complement of ELOVL4 genes and the functions of their corresponding encoded enzymes. For a better understanding of the metabolism and the potential tissue‐specific requirements of VLC‐FA in marine teleosts, the present study aimed to determine the tissue‐expression pattern of genes that coding for both ELOVL4 isoforms, ELOVL4a and ELOVL4b, in different windows of development (larvae and adults) of S. aurata and S. senegalensis.[Materials and methods]: Tissue expression of ELOVL4 genes in 24 hours post‐hatching (hph) larvae. Whole‐mount in situ hybridization (WISH). Tissue expression of ELOVL4 genes in adult fish. RT‐PCR (screening) and qPCR (selected tissues).[Results and Discussion]: S. aurata larvae: in agree with the observed in Danio rerio larvae [1], ELOVL4a was widely distributed in the head region (Fig. 1B). Moreover, ELOVL4b was specifically expressed in the eyes (Fig. 2C) showing a strong signal in the retinal epithelium (Fig. 2D). No signal was detected for sense control probes of ELOVL4a (Fig. 1A) and ELOVL4b (Fig. 2A, B) genes.AGL2013‐40986‐R,AGL2011‐ 23502 (MINECO) and PROMETEO II / 2014/085 (G.V.).Peer reviewe

  • Lipid metabolism in Tinca tinca and its n-3 LC-PUFA biosynthesis capacity
    'Elsevier BV', 2020
    Co-Authors: Garrido Diego, Monroig Óscar, Kabeya Naoki, Betancor Monica, Galindo Ana, Perez, Jose Antonio, Marrero Manuel, Rodríguez Covadonga
    Abstract:

    Carps, barbels and other cyprinids are the major contributors to freshwater aquaculture at global scale. Nevertheless, freshwater fish aquaculture needs to diversify their production in order to offer consumers new species. Tench (Tinca tinca) is a freshwater species with great interest for the diversification of continental aquaculture. However, up to date, no commercial formulated diet exists for this species in order to optimize their nutritional requirements and the quality of its final product. Using multiple methodological approaches, the aim of this study was to evaluate the long chain polyunsaturated fatty acid (LC-PUFA) metabolism of T. tinca. Firstly, the molecular cloning and functional characterisation by heterologous expression in yeast of a desaturase (Fads2) and two elongases (Elovl2 and Elovl5) involved in LC-PUFA biosynthesis, and the analysis of gene expression among tissues were performed. Secondly, in order to confirm the LC-PUFA biosynthesis capacity of isolated hepatocytes and enterocytes, cells were incubated with [1-14C] labelled linoleic acid (18:2n-6, LA), linolenic acid (18:3n-3, ALA) and eicosapentaenoic acid (20:5n-3, EPA). In yeast, Fads2 showed a Δ6/Δ5 bifunctional activity. Elovl2 was more active over C20 and C22 substrates, whereas Elovl5 was over C18 and C20. Liver displayed the highest expression for the three target genes (fads2, elovl2 and elovl5). Incubated cells also showed Fads2 bifunctional activity as well as elongation products in concordance with yeast heterologous expression results. Importantly, our results demonstrated that tench is able to biosynthesise docosahexaenoic acid (DHA) from 18:3n-3 in both hepatocytes and enterocytes, a capacity that seems to explain in part the surprisingly high levels of DHA found in the fish flesh compared to its dietary supply. Tench is a promising freshwater species with a potential capacity to endogenously increase its flesh DHA contents, reducing the impact that the usage of fish oils from forage fisheries may have on the aquaculture industry