Preferential accumulation of fatty acids in the testis and ovary of cultured and wild sweet smelt Plecoglossus altivelis

Transcriptomic Insights into Post-Spawning Death and Muscle Atrophy in Ayu (Plecoglossus altivelis)

In semelparous species like the ayu (Plecoglossus altivelis), spawning is followed by rapid physiological decline and death; yet, the underlying molecular mechanisms remain largely unexplored. This study examines transcriptomic changes in ayu skeletal muscle before and after spawning, with a focus on key genes and pathways contributing to muscle atrophy and metabolic dysfunction. Through RNA sequencing and DEG analysis, we identified over 3000 DEGs, and GSEA and KEGG pathway analysis revealed significant downregulation of energy metabolism and protein degradation. In post-spawning ayu, a rapid decrease in body weight was observed, accompanied by a decline in the expression of myosin heavy chain genes, which are major muscle protein genes, and gene expression changes indicative of muscle atrophy. Decreased expression of AP-1 transcription factors associated with muscle development and aging was also evident. PPI network analysis identified carbohydrate catabolism protein gapdh may be the key factor that led to muscle atrophy and accelerated aging in ayu. Our study revealed that after spawning, the ayu muscle tissue undergoes strong metabolic disorders and cellular stress responses, providing special insights into the mechanisms through the post-spawning death of ayu.

Significance of fatty acids in fish broodstock nutrition

The nutritional status of broodstock profoundly affects their reproductive performance and offspring survival. Studies on lipids and essential fatty acids in broodstock diets highlight their importance in cell structure, fecundity, fertilization, egg and larval quality, and providing metabolic energy for reproduction. Long-chain polyunsaturated fatty acids (Lc-PUFA) like DHA (22:6 n-3) and EPA (20:5 n-3) are vital for egg and larval development, while arachidonic acid (ARA) produces eicosanoids essential for reproduction. The fatty acid requirements vary by habitat; freshwater fish typically lack ∆12 and ∆15 desaturase enzymes to convert oleic acid into vital polyunsaturated fatty acids like linoleic and linolenic acids but can synthesize linoleic (18:2 n-6) and linolenic (18:3 n-3) into Lc-PUFAs such as EPA, DHA, and ARA through desaturation and elongation, whereas marine teleost cannot. Hence, broodstock feed fatty acid composition must be tailored by incorporating ingredients with a specific fatty acid composition to enhance reproductive performance. This review provides updated information on fatty acid supplementation in broodstock diets to improve reproductive outcomes in commercially important finfish, offering valuable insights for researchers, academicians, hatchery owners, and fish farmers to produce better-quality seeds.

A complete biosynthetic pathway of the long-chain polyunsaturated fatty acids in an amphidromous fish, ayu sweetfish Plecoglossus altivelis (Stomiati; Osmeriformes)

The biosynthetic capability of the long-chain polyunsaturated fatty acids (LC-PUFA) in teleosts are highly diversified due to evolutionary events such as gene loss and subsequent neo- and/or sub-functionalisation of enzymes encoded by existing genes. In the present study, we have comprehensively characterised genes potentially involved in LC-PUFA biosynthesis, namely one front-end desaturase (fads2) and eight fatty acid elongases (elovl1a, elovl1b, elovl4a, elovl4b, elovl5, elovl7, elovl8a and elovl8b) from an amphidromous teleost, Ayu sweetfish, Plecoglossus altivelis. Functional analysis confirmed Fads2 with Δ6, Δ5 and Δ8 desaturase activities towards multiple PUFA substrates and several Elovl enzymes exhibited elongation capacities towards C18-20 or C18-22 PUFA substrates. Consequently, P. altivelis possesses a complete enzymatic capability to synthesise physiologically important LC-PUFA including arachidonic acid (ARA, 20:4n-6), eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) from their C18 precursors. Interestingly, the loss of elovl2 gene in P. altivelis was corroborated by genomic and phylogenetic analyses. However, this constraint would possibly be overcome by the function of alternative Elovl enzymes, such as Elovl1b, which has not hitherto been functionally characterised in teleosts. The present study contributes novel insights into LC-PUFA biosynthesis in the relatively understudied teleost group, Osmeriformes (Stomiati), thereby enhancing our understanding of the complement of LC-PUFA biosynthetic genes within teleosts.

Nutrient Composition of Ovary, Hepatopancreas and Muscle Tissues in Relation to Ovarian Development Stage of Female Swimming Crab, Portunus trituberculatus

The swimming crab Portunus trituberculatus is one of the most important economic species in China and its mature ovary often determines its commercial value and production. Although the ovary maturation of crustaceans is generally affected by exogenous nutrition, the specific nutritional needs of ovary maturation of P. trituberculatus are poorly understood. To this end, we collected the P. trituberculatus samples with five ovarian maturation stages and measured their biochemical composition of the ovary, hepatopancreas, and muscle at each ovarian developmental stage. We further analyzed their relation to the ovarian developmental stage of P. trituberculatus by principal components analysis (PCA). We found the levels of branched-chain amino acids, long-chain polyunsaturated fatty acids (LC-PUFA), and monounsaturated fatty acids (MUFAs) in the ovary and hepatopancreas increased during the ovary maturation process, and also passively correlated with ovarian developmental stage, which highlights the necessity of these specific nutrients for oogenesis and for improving the nutrient quality of crabs. In addition, we found an increasing tendency of carotenoid content and phosphatidylcholine in phospholipid in the ovary from the pre-developmental stage to the proliferative stage, but not in the hepatopancreas and muscle, which highlights the possible involvement of carotenoids during the rapid oocyte development process. Our study may provide valuable information for developing a suitable broodstock diet that promotes the ovarian maturation of adult P. trituberculatus and ensures high-quality larval production.

Wild coral oocytes are more amenable to low temperature preservation than cultured counterparts

Few studies have examined the biochemical differences between cultured and wild coral after undergoing low-temperature preservation. The present study aimed to explore the differences in the biochemical characteristics of cultured and wild coral cells and oocytes (Echinopora gemmacea and Oxypora lacera) in cryopreservation conditions. Wild and cultured coral cells were extracted and subjected to freezing experiments involving multiple types and concentrations of cryoprotectant, and the oocytes from the cultured and wild corals were subjected to chilling experiments. Cultured and wild coral cells exhibited no significant differences in viability or cell density after cryopreservation, whereas the oocytes from the cultured corals E. gemmacea and O. lacera exhibited lower chilling tolerance compared with their wild counterparts. Significant differences were observed between the oocytes from the cultured and wild corals after low-temperature preservation, particularly in their metabolic activity and vital status, which could be possibly attributed to food consumption and environmental factors. The study provides a foundation for research promoting the technological development of artificial coral propagation and cryopreservation.

Seasonal effects of the fatty acid composition of phospholipid and triacylglycerol in the muscle and liver of male Salmo trutta macrostigma

The seasonal effects on the fatty acid composition of triacylglycerol (TAG) and phospholipid (PL) in the muscle and liver of male Salmo trutta macrostigma were determined using the gas chromatographic (GC) method. The fatty acid (FA) compositions of total lipid, PL and TAG fractions were determined in muscle and liver tissues of S. trutta macrostigma. The phospholipids contained a higher proportion of 16:0 compared to the TAG in the muscle tissue of S. trutta macrostigma. Docosahexaenoic acid (22:6 ω-3) and eicosapentaenoic acid (20:5 ω-3) contents were high in both muscle and liver tissues. The total lipid contents in the muscle and liver were 1.07-2.45 and 3.00-4.64%, respectively. S. trutta macrostigma is a rich source of ω-3 and ω-6, polyunsaturated fatty acids (PUFA) with numerous benefits to human health.

Recovery of Fatty Acid Composition in Mediterranean Yellowtail (Seriola dumerili, Risso 1810) fed a Fish-Oil Finishing Diet

The present study evaluated the effects of wash-out on the fatty acid (FA) composition in the muscles of Mediterranean yellowtail. After 109 days during which fish were fed either a fish oil (FO)-based diet (FO 100) or a diet (FO 0) in which FO was completely substituted by vegetable oils, all fish were subjected to a wash-out with FO 100 diet for 90 days. The FA profile of muscles in fish fed FO 0 diet at the beginning of the experiment reflected that of dietary vegetable oils, rich in linoleic acid (LA), and α-linolenic acid (ALA), and was deficient in AA (arachidonic acid), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). No essential FA were fully restored in fish previously fed FO 0 diet on 45th or 90th day of wash-out. At the end of wash-out, the FA composition showed that AA, EPA, and DHA in the white muscles increased by +33%, +16%, and +43% (p < 0.001), respectively. Similarly, AA and DHA in the red muscles increased by +33% and +41% respectively, while EPA remained similar to fish fed FO 0 diet exclusively. Therefore, a 90-d wash-out can partially improve the FA profile in muscles of Mediterranean yellowtail previously fed vegetable oil-based diets.

Fatty acids in an iteroparous fish: variable complexity, identity, and phenotypic correlates

Ecologists often focus on summarized composition when assessing complex, multivariate phenotypes such as fatty acids. Increasing complexity in fatty acid composition may offer benefits to individuals that may not be recognized by assessing mean fatty acid identity. We quantified fatty acid identity and complexity in the egg and muscle of spawning female yellow perch (Perca flavescens (Mitchill, 1814)) exposed to three overwinter thermal regimes (4, 8, and 13 °C) to evaluate (i) thermal regulation of fatty acid complexity, (ii) fatty acid complexity and identity differences between female muscle and eggs, and (iii) relationships between fatty acid complexity and egg traits. Temperature did not alter fatty acid complexity in either tissue. Muscle contained an even distribution of 12 abundant polyunsaturated fatty acids (PUFA), while eggs exhibited a simpler phenotype of eight compounds. Fatty acid complexity in female muscle was positively correlated with potential indicators of egg quality, including size and lipid content. Preferential allocation of fatty acids to eggs by females likely contributed to a simple phenotype dominated by PUFA precursors and energy sources, while muscle represented a more complex fatty acid phenotype. Recognizing complexity could elucidate variation in reproductive condition among individuals, while identifying patterns in fatty acid allocation among populations.

Production of a Health-Beneficial Food Emulsifier by Enzymatic Partial Hydrolysis of Phospholipids Obtained from the Head of Autumn Chum Salmon

Phospholipids and their partial hydrolysates, namely lysophospholipids (LPLs), have been widely used in food, pharmaceutical, and cosmetic products as highly efficient emulsifiers. This study was conducted to produce docosahexaenoic acid (DHA)-esterified LPLs by enzymatic modification of phospholipids obtained from the head of autumn chum salmon (Oncorhynchus keta). The emulsifying properties of the obtained LPLs were also evaluated. Two different types of substrates of salmon head phospholipids were prepared via silica gel and cold acetone precipitation. Enzymatic partial hydrolysis was carried out using immobilized phospholipase A₁ (PLA₁) and Lipozyme RM IM. Results showed that the increase in DHA in the LPLs was much higher in the silica-separated phospholipids than in the acetone-precipitated phospholipids. When silica-separated phospholipids were used as the substrate, the DHA content of the LPLs increased from 23.1% to 40.6% and 42.6% after 8 h of partial hydrolysis with Lipozyme RM IM and immobilized PLA₁, respectively. The yield of the LPLs was comparatively higher in the Lipozyme RM IM than in the immobilized PLA₁ hydrolysis reaction. The critical micelle concentration values of the LPLs and purified lysophosphatidylcholine (LPC) were 100 mg/L and 5 mg/L, respectively. The surface tension values of the LPLs and LPC were reduced to 30.0 mN/m and 30.5 mN/m, respectively. The hydrophilic-lipophilic balance of the LPLs and LPC were 6.0 and 9.4, respectively. Based on the emulsifying properties observed, we conclude that LPLs derived from the phospholipids of salmon head lipids could be used as a health-beneficial emulsifier in the food industry.

Nutritional modifications in male infertility: a systematic review covering 2 decades

CONTEXT

Studies suggest that appropriate nutritional modifications can improve the natural conception rate of infertile couples.

OBJECTIVES

The purpose of this study was to review the human trials that investigated the relation between nutrition and male infertility.

DATA SOURCES

A comprehensive systematic review of published human studies was carried out by searching scientific databases. Article selection was carried out in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The American Dietetic Association Research Design and Implementation Checklist was also used for quality assessment.

DATA EXTRACTION

A total of 502 articles were identified, of which 23 studies met the inclusion criteria.

DATA SYNTHESIS

Results indicated that a healthy diet improves at least one measure of semen quality, while diets high in lipophilic foods, soy isoflavones, and sweets lower semen quality.

CONCLUSION

The role of daily nutrient exposure and dietary quality needs to be highlighted in male infertility. Mechanistic studies addressing the responsible underlying mechanisms of action of dietary modifications are highly warranted.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2013: CRD42013005953. Available at: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42013005953.

Processed meat intake is unfavorably and fish intake favorably associated with semen quality indicators among men attending a fertility clinic

Emerging literature suggests that men's diets may affect spermatogenesis as reflected in semen quality indicators, but literature on the relation between meat intake and semen quality is limited. Our objective was to prospectively examine the relation between meat intake and indicators of semen quality. Men in subfertile couples presenting for evaluation at the Massachusetts General Hospital Fertility Center were invited to participate in an ongoing study of environmental factors and fertility. A total of 155 men completed a validated food-frequency questionnaire and subsequently provided 338 semen samples over an 18-mo period from 2007-2012. We used linear mixed regression models to examine the relation between meat intake and semen quality indicators (total sperm count, sperm concentration, progressive motility, morphology, and semen volume) while adjusting for potential confounders and accounting for within-person variability across repeat semen samples. Among the 155 men (median age: 36.1 y; 83% white, non-Hispanic), processed meat intake was inversely related to sperm morphology. Men in the highest quartile of processed meat intake had, on average, 1.7 percentage units (95% CI: -3.3, -0.04) fewer morphologically normal sperm than men in the lowest quartile of intake (P-trend = 0.02). Fish intake was related to higher sperm count and percentage of morphologically normal sperm. The adjusted mean total sperm count increased from 102 million (95% CI: 80, 131) in the lowest quartile to 168 million (95% CI: 136, 207) sperm in the highest quartile of fish intake (P-trend = 0.005). Similarly, the adjusted mean percentages of morphologically normal sperm for men in increasing quartiles of fish intake were 5.9 (95% CI: 5.0, 6.8), 5.3 (95% CI: 4.4, 6.3), 6.3 (95% CI: 5.2, 7.4), and 7.5 (95% CI: 6.5, 8.5) (P-trend = 0.01). Consuming fish may have a positive impact on sperm counts and morphology, particularly when consumed instead of processed red meats.

Lipid and fatty acid composition, and persistent organic pollutant levels in tissues of migrating Atlantic bluefin tuna (Thunnus thynnus, L.) broodstock

Lipid class, fatty acid and POP levels were measured in migrating Atlantic bluefin tuna (ABT) tissues caught off the Barbate coast, Spain. Tissue lipids were largely characterized by triacylglycerol, reflecting large energy reserves accumulated prior to reproductive migration. Fatty acid compositions of muscle, liver and adipose exhibited similar profiles, whereas gonads showed a higher affinity for docosahexaenoic acid. Tissue POP concentrations correlated positively with percentage triacylglycerol and negatively with polar lipids. Highest POP concentrations were in adipose and lowest in gonads, reflecting lipid content. DL-PCBs contributed most to total PCDD/F + DL-PCB levels, with mono-ortho concentrations higher in tissues, whereas non-ortho PCBs contributed greater WHO-TEQs due to differences in TEFs. PBDE47 was the most prominent BDE congener in tissues, probably through biotransformation of BDE99 and other higher brominated congeners. The perceived POP risk from ABT consumption should be balanced by the well-established beneficial effects on human health of omega-3 fatty acids.

Effect of animal feed enriched with Se and clays on Hg bioaccumulation in chickens: in vivo experimental study

An in vivo experiment was conducted to evaluate the effects of sodium selenite, sepiolite, and bentonite on inorganic mercury (Hg) and methylmercury (MeHg) bioaccumulation. For this purpose 160 chickens were fed under different controlled conditions. Chickens were exposed to Hg(II) and MeHg added to feed with or without selenium or clays supplementation. No significant differences were observed in the voluntary intake and feed/gain conversion rates. The target organs of Hg(II) and MeHg in chickens were the liver and kidney, respectively, but the greatest body store was the muscle in both cases. A higher bioaccumulation for MeHg than for Hg(II) was observed. The results showed that addition of sodium selenite, sepiolite, or bentonite induced a decrease of up to 60-100% in the inorganic mercury bioabsorption. Bentonite addition to a MeHg-containing diet also caused a decrease in organic mercury bioaccumulation (29-67%). On the other hand, inorganic selenium and sepiolite did not decrease MeHg accumulation.