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The present study assessed the growth and fish performance of juvenile red sea bream fed four isonitrogenous (46–48%) and isolipidic (15%) diets containing 45% fishmeal (control) and 15%, 30%, and 45% defatted black soldier fly (BSF) Hermetia illucens meal for 67 days. Subsequent analyses showed that there were no significant differences in the growth parameters, nutrient digestibility, and body composition of fish among all treatments. Although no significant difference was observed in fish growth, low growth was observed when the fish meal was totally replaced with the BSF meal. Higher alpha diversity of intestinal microbiota was observed in fish fed the BSF meal-based diet compared to that of the control. In the treatment groups fed the BSF meal, elevations in the presence of microbial genera that produce digestive enzymes, such as chitinase (Nocardia, Vibrio, Paenibacillus, Photobacterium), lipase (Paenibacillus, Photobacterium), and trypsin-like serine protease (Bacillus, Paenibacillus) and vitamin B group [biotin (Vibrio, Paenibacillus, Bacillus), cobalamin (Pseudomonas, Bacillus, Propionibacterium), and pyridoxin (Photobacterium)], were observed. We also found an increasing trend of bacteria producing antioxidative enzymes, such as superoxide dismutase and catalase (Nocardia, Pseudomonas, Photobacterium) in the BSF groups. These results suggested that the BSF meal could replace 67% of fishmeal without causing a negative impact on growth and lead to beneficial effects on the intestinal microbiota of the red sea bream. [ABSTRACT FROM AUTHOR]

The Pacific saury Cololabis saira is an important fishery resource in the Far East, where it is appreciated for its high lipid content, which includes long-chain polyunsaturated fatty acids (LC-PUFAs) such as docosahexaenoic acid (DHA). Although it has been hypothesized that these fatty acids are derived from their prey items, this study focused on evaluating the capacity of saury for endogenous production of LC-PUFAs. To describe its LC-PUFA biosynthetic pathway, we characterized fatty acid desaturase 2 (Fads2) and elongation of very long-chain fatty acid protein 5 (Elovl5) in Pacific saury. Two paralogous fads2 genes, namely fads2a and fads2b, were isolated from the saury and their recombinant protein showed ∆6∆8 and ∆4∆5 desaturase activities, respectively. Meanwhile, saury Elovl5 had elongase activity toward C18 and C20 PUFA. These three enzyme genes were expressed in the brain and liver, although fads2a was absent in the latter. Our results suggest that the saury has sufficient enzymatic functions, particularly in its brain, for DHA biosynthesis through the ∆4 pathway even from α-linolenic acid. This information provides novel insights into the origin of LC-PUFAs in Pacific saury and the future perspective for its potential as a source of such vital fatty acids for human consumption. [ABSTRACT FROM AUTHOR]

The splendid alfonsino Beryx splendens is a commercially important deep-sea fish in East Asian countries. Because the wild stock of this species has been declining, there is an urgent need to develop aquaculture systems. In the present study, we investigated the long-chain polyunsaturated fatty acid (LC-PUFA) requirements of B. splendens, which are known as essential dietary components in many carnivorous marine fish species. The fatty acid profiles of the muscles, liver, and stomach contents of B. splendens suggested that it acquires substantial levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from its natural diet. The functional characterization of a fatty acid desaturase (Fads2) and three elongases (Elovl5, Elovl4a, and Elovl4b) from B. splendens confirmed their enzymatic capabilities in LC-PUFA biosynthesis. Fads2 showed Δ6 and Δ8 bifunctional desaturase activities. Elovl5 showed preferential elongase activities toward C18 and C20 PUFA substrates, whereas Elovl4a and Elovl4b showed activities toward various C18–22 substrates. Given that Fads2 showed no Δ5 desaturase activity and no other fads-like sequence was found in the B. splendens genome, EPA and arachidonic acid cannot be synthesized from C18 precursors; hence, they can be categorized as dietary essential fatty acids in B. splendens. EPA can be converted into DHA in B. splendens via the so-called Sprecher pathway. However, given that fads2 is only expressed in the brain, it is unlikely that the capacity of B. splendens to biosynthesize DHA from EPA can fulfill its physiological requirements. These results will be useful to researchers developing B. splendens aquaculture methods. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Capability of DHA biosynthesis in a marine teleost, Pacific saury Cololabis saira: functional characterization of two paralogous Fads2 desaturases and Elovl5 elongase." The article was originally published without open access but has now been made available as an open access publication. The copyright of the article has been changed to © The Author(s) 2024, and it is distributed under the Creative Commons Attribution 4.0 International License. The original article has been corrected. Springer Nature, the publisher, remains neutral regarding jurisdictional claims and institutional affiliations. [Extracted from the article]

Here, we investigated the effect of dietary cysteic acid on the growth performance, sulfur amino acid content, and gene expression levels of taurine-synthesizing enzymes, growth hormone (GH), and insulin-like growth factor 1 (IGF-1) in Japanese flounder Paralichthys olivaceus. Juvenile flounder (0.9 g) were fed one of four diets for 30 days: with 0.25, 0.5, or 1.0% cysteic acid (C0.25, C0.5, C1.0) supplementation and without supplementation (control). Fish in the C0.25 and C0.5 groups showed significantly better growth than those in the control group (P < 0.05). Body taurine content was significantly higher in C0.25, C0.5, and C1.0 fish than in control fish (P < 0.05). Although there was no significant difference in gene expression levels of taurine-synthesizing enzymes and GH among groups (P > 0.05), the expression level of IGF-1 in C1.0 fish was significantly higher than that in controls (P < 0.05). Our results suggest that Japanese flounder can synthesize taurine from cysteic acid, that dietary supplementation with up to 0.5% cysteic acid promotes fish growth, and that dietary cysteic acid can affect the GH-IGF axis in Japanese flounder. These findings thus highlight the importance of the cysteic acid pathway for taurine synthesis and growth in this species. [ABSTRACT FROM AUTHOR]

B Correction: Fisheries Science b https://doi.org/10.1007/s12562-023-01710-9 There were incorrect descriptions of the activity of 24:4n-6 and 24:5n-3 in Table 1. [Extracted from the article]

Invertebrates represent a large proportion of the biomass in aquatic ecosystems, particularly in the ocean. In recent years, invertebrates have been well-consolidated models in evolutionary developmental biology research and, consequently, genomic and transcriptomic sequence databases from a plethora of species across the animal kingdom have become available. This has provided an excellent source of evidence confirming that invertebrates operate endogenous mechanisms for PUFA production. The present paper reviews the current knowledge of gene complement and, where possible, the function of desaturases and elongases with pivotal roles in PUFA biosynthesis of aquatic invertebrates. More specifically, this review covers three major enzyme types, namely ωx desaturases, front-end desaturases and elongases, that have been characterised from species of sponges, cnidarians, molluscs, annelids, crustaceans, rotifers, echinoderms and non-vertebrate chordates (amphioxus and sea squirt). These studies have shown that invertebrates operate alternative and unusual pathways of PUFA biosynthesis involving gene families with complex phylogeny and functional diversity. Consequently, research in this area provides potentially valuable molecular tools in the form of genes that can be used in the biotechnological production of n-3 products. [ABSTRACT FROM AUTHOR]

We identified fatty acid desaturase ( fads)-like and elongase ( elovl)-like genes from nibe croaker to better understand the molecular basis of n-3 highly unsaturated fatty acid metabolism in marine fish. Phylogenetic analysis revealed that the fads-like and elovl-like genes were classified into the fads6 and elovl5 groups, respectively. We investigated the effects of various levels of docosahexaenoic acid (DHA)-enriched live feed, Artemia nauplii, on larval growth, survival, and fads-like and elovl-like gene expression. After a 15-day feed trial, total length, body weight, and survival were all significantly improved by the supplementation of Artemia with DHA. This result indicates that nibe croaker cannot endogenously produce enough DHA. Furthermore, the fads-like gene transcripts in larvae fed on oleic acid-enriched Artemia were significantly higher than those in larvae on 100% DHA-enriched Artemia. In contrast, no significant differences were observed in the transcript levels of the elovl-like gene. These data indicate that the fads6-like gene was controlled by negative feedback from the quantity of DHA stored in the larval body. These results have implications for the functionality of the fads-like gene in nibe croaker. [ABSTRACT FROM AUTHOR]

The colonisation of freshwater environments by marine fishes has historically been considered a result of adaptation to low osmolality. However, most marine fishes cannot synthesise the physiologically indispensable fatty acid, docosahexaenoic acid (DHA), due to incomplete DHA biosynthetic pathways, which must be adapted to survive in freshwater environments where DHA is poor relative to marine environments. By analysing DHA biosynthetic pathways of one marine and three freshwater-dependent species from the flatfish family Achiridae, we revealed that functions of fatty acid metabolising enzymes have uniquely and independently evolved by multi-functionalisation or neofunctionalisation in each freshwater species, such that every functional combination of the enzymes has converged to generate complete and functional DHA biosynthetic pathways. Our results demonstrate the elaborate patchwork of fatty acid metabolism and the importance of acquiring DHA biosynthetic function in order for fish to cross the nutritional barrier at the mouth of rivers and colonise freshwater environments. Matsushita et al. demonstrate the evolution of DHA biosynthetic mechanisms in four species of flatfish as some of them colonised freshwater environments. Their analyses show independent changes to the biosynthetic pathways as a way to overcome the lack of exogenous DHA that would typically be available from prey in the marine environment. [ABSTRACT FROM AUTHOR]

The long-chain (≥C20) polyunsaturated fatty acid biosynthesis capacity of fish varies among species, with trophic level hypothesised as a major factor. The biosynthesis capacity is largely dependent upon the presence of functionally diversified fatty acyl desaturase 2 (Fads2) enzymes, since many teleosts have lost the gene encoding a Δ5 desaturase (Fads1). The present study aimed to characterise Fads2 from four teleosts occupying different trophic levels, namely Sarpa salpa, Chelon labrosus, Pegusa lascaris and Atherina presbyter, which were selected based on available data on functions of Fads2 from closely related species. Therefore, we had insight into the variability of Fads2 within the same phylogenetic group. Our results showed that Fads2 from S. salpa and C. labrosus were both Δ6 desaturases with further Δ8 activity while P. lascaris and A. presbyter Fads2 showed Δ4 activity. Fads2 activities of herbivorous S. salpa are consistent with those reported for carnivorous Sparidae species. The results suggested that trophic level might not directly drive diversification of teleost Fads2 as initially hypothesised, and other factors such as the species' phylogeny appeared to be more influential. In agreement, Fads2 activities from P. lascaris and A. presbyter were similar to their corresponding phylogenetic counterparts Solea senegalensis and Chirostoma estor. [ABSTRACT FROM AUTHOR]

Since the late 19th century, the Amazon species Colossoma macropomum (tambaqui) has been exploited commercially and the climate change has contributed to decline in tambaqui numbers. Although germ cell cryopreservation and transplantation can help preserve the species' genetic resources semipermanently, its germ cell behavior has not been analyzed to date. In this study, we isolated the tambaqui's dead end gene (dnd) homolog (tdnd) and used it as a molecular marker for germ cells to obtain basic information essential for transplantation. The amino acid sequence showed 98% similarity and 53% identity with the zebrafish dnd. Phylogenetic analysis and the presence of consensus motifs known for dnd revealed that tdnd encodes the dnd ortholog and its transcript is detectable only in the testes and ovaries, showing a strong positive signal in oocytes and spermatogonia. The tambaqui possesses, at least, three different transcripts of tdnd which show dissimilar expression profile in undifferentiated and sexually mature animals, suggesting that they play distinct roles in germline development and they may influence the choice of donors for the cell transplantation study. [ABSTRACT FROM AUTHOR]