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A 100‐day feeding trial was conducted to investigate the influences of dietary lipid levels on the immunity and mechanism in abalone Haliotis discus hannai Ino. Abalones (initial weight: 10.98 ± 0.05 g) were fed with graded levels of dietary lipid, which were 15.73, 23.41, 31.72, 38.25, 46.35, 55.63, 61.70 and 67.19 g/kg. Results showed that compared with the treatment with 38.25 g/kg of dietary lipid, 67.19 g/kg of dietary lipid increased the cumulative mortality of abalone after a challenge with Vibrio parahaemolyticus. Meanwhile, 67.19 g/kg of dietary lipid decreased the activities of lysozyme (LZ) and acid phosphatase (ACP) in serum, and the mRNA levels of β‐defensin and mytimacin 6 in hepatopancreas of abalone. The mRNA levels of tumour necrosis factor α (tnfα), activator protein 1 (ap‐1), nuclear factor κB (nf‐κb), interleukin 1 receptor‐associated kinase‐4 (irak4), myeloid differentiation primary response protein MyD88 (myd88), toll‐like receptor 2 (tlr2), tlr4 and perilipin‐2, and the protein level of interleukin‐1β (IL‐1β), TNFα, NF‐κBp65, AP‐1, MyD88 and Perilipin‐2 in hepatopancreas were up‐regulated by 67.19 g/kg of dietary lipid. However, the mRNA levels of arginase and inhibitor of κBα (iκbα) were down‐regulated. Besides, 67.19 g/kg of dietary lipid up‐regulated the mRNA levels of executor apoptosis‐related cysteine peptidase 3 (caspase‐3), caspase‐7 and B‐cell lymphoma protein‐2‐associated X protein (bax), and the protein levels of caspase‐3 and c‐Jun N‐terminal kinases (JNK) in hepatopancreas. Moreover, high dietary lipid level down‐regulated the mRNA levels of copper/zinc superoxide dismutase (cuznsod), manganese superoxide dismutase (mnsod), catalase (cat), glutathione peroxidase (gpx), glutathione‐S‐transferase (gst) and NF‐E2‐related factor 2 (nrf2), while up‐regulated the mRNA and protein levels of Kelch‐like ECH‐associated protein 1 (Keap1) in hepatopancreas. It was concluded that a high level (67.19 g/kg) of dietary lipid decreased the immunity of abalone, which might be related to the aggravated inflammation and apoptosis, and decreased anti‐oxidative capacity under Perilipin‐2/TLRs/MyD88/IRAK4/(NF‐κB or AP‐1), JNK/Bcl‐2/Bax and Keap1/Nrf2 signalling. [ABSTRACT FROM AUTHOR]

A 115‐day feeding trial and subsequently a 10‐day challenge test with Vibrio parahaemolyticus were conducted to investigate the effects of dietary antimicrobial peptide APSH‐07 on growth performance, immune response, antioxidative status and vibriosis resistance of abalone Haliotis discus hannai (initial body weight: 2.06 ± 0.01 g; initial shell length: 25.42 ± 0.18 mm). Four artificial diets were designed with 0 (artificial diet control), 7.5, 15.0 and 22.5 mg/kg of APSH‐07, respectively. The brown alga Laminaria japonica was used as the live food control. Results showed that the specific growth rates of abalone in the groups with 7.5 and 15.0 mg/kg dietary APSH‐07 were significantly higher than those in the controls (p <.05). The total haemocyte counts and respiratory burst activity in haemolymph of abalone in the group with 7.5 mg/kg of dietary APSH‐07 were significantly higher than those in the groups with 0 and 22.5 mg/kg of dietary APSH‐07 (p <.05). The gene expression levels of Mn‐superoxide dismutase and thioredoxin peroxidase 2, and the activities of glutathione peroxidase in the group with 7.5 mg/kg of dietary APSH‐07 were significantly higher than those in the other groups (p <.05). Cumulative mortality of abalone after the challenge test was significantly decreased in the group with 7.5 mg/kg of dietary APSH‐07 supplementation. Supplementation of 22.5 mg/kg dietary APSH‐07 significantly increased the cumulative mortality. In conclusion, 7.5 mg/kg of dietary APSH‐07 supplementation had the better growth performance, higher antioxidation, immune and disease resistance capacity of abalone. Excessive supplementation of dietary antimicrobial peptide APSH‐07 (22.5 mg/kg) had significantly negative effects. Further studies are needed to determine the optimal level of dietary APSH‐07 supplementation for abalone. [ABSTRACT FROM AUTHOR]

Abstract: This study was conducted to investigate protective effects of dietary selenium (Se) on abalone Haliotis discus hannai Ino against the toxicity of cadmium (Cd). A 60‐day feeding trial was conducted with abalone (initial weight: 3.17 ± 0.01 g), which were exposed to 0.34 mg/L of waterborne Cd. During a feeding trial, abalone were fed graded levels of Se at 0.10 (controls), 1.31, and 4.20 mg/kg diet respectively. Results showed that there was no significant difference in specific growth rate and survival rate of abalone among the three treatments. Compared with the controls, dietary Se significantly decreased Cd concentrations in serum, muscle, mantle, gill, mantle, and hepatopancreas of abalone. Besides, compared with the controls, dietary Se significantly increased metallothionein concentration in the hepatopancreas of abalone. Additionally, compared with the controls, dietary Se significantly decreased concentrations of malondiadehyde and protein carbonyl in hepatopancreas of abalone. Meanwhile, compared with the controls, dietary Se significantly increased activities of glutathione peroxidase, thioredoxin reductase, and thioredoxin peroxidase, and concentration of glutathione in the hepatopancreas of abalone. Based on the data above, in abalone, dietary Se showed protective effects against waterborne Cd. [ABSTRACT FROM AUTHOR]

Arginine plays an important role in the regulation of the target of the rapamycin (TOR) signaling pathway, and Solute Carrier Family 38 Member 9 (SLC38A9) was identified to participate in the amino acid-dependent activation of TOR in humans. However, the regulations of arginine on the TOR signaling pathway in abalone are still unclear. In this study, slc38a9 of abalone was cloned, and the slc38a9 was knocked down and overexpressed to explore its function in the regulation of the TOR signaling pathway. The results showed that knockdown of slc38a9 decreased the expression of tor, ribosomal s6 protein kinase (s6k) and eukaryotic translation initiation factor 4e (eif4e) and inhibited the activation of the TOR signaling pathway by arginine. Overexpression of slc38a9 up-regulated the expression of TOR-related genes. In addition, hemocytes of abalone were treated with 0, 0.2, 0.5, 1, 2 and 4 mmol/L of arginine, and abalones were fed diets with 1.17%, 1.68% and 3.43% of arginine, respectively, for 120 days. Supplementation of arginine (0.5–4 mmol/L) increased the expressions of slc38a9, tor, s6k and eif4e in hemocytes, and abalone fed with 1.68% of dietary arginine showed higher mRNA levels of slc38a9, tor, s6k and eif4e and phosphorylation levels of TOR, S6 and 4E-BP. In conclusion, the TOR signaling pathway of abalone can be regulated by arginine, and SLC38A9 plays an essential role in this regulation. [ABSTRACT FROM AUTHOR]

A 100-day feeding trial was conducted to investigate the effects of dietary lipid on growth performance and lipid deposition as well as the regulation mechanism in abalone Haliotis discus hannai Ino. Abalones (initial weight: 10.98 ± 0.05 g) were fed with graded levels of dietary lipid (1.57%, 2.34%, 3.17%, 3.82%, 4.63%, 5.56%, 6.17% and 6.72%). Results showed that weight gain rate (WGR) and increment in shell length of abalone were highest in 3.82% dietary lipid level. Based on the quadratic regression analysis for WGR, the optimal dietary lipid level for abalone was estimated to be 3.87%. Concentrations of the total triacylglycerol, low-density lipoprotein cholesterol and non-esterified fatty acids in serum as well as lipid contents in hepatopancreas and muscle were positively related to dietary lipid levels. Compared to the group with 3.82% of dietary lipid, higher (6.72%) and lower (1.57%) dietary lipid down regulated the expression of genes involved in fatty acids transport and lipolysis in hepatopancreas and muscle, which might be related to AMP-activated protein kinase α2 (AMPKα2)/peroxisome proliferator-activated receptor α (PPARα) signaling. Higher dietary lipid (6.72%) down regulated, while lower dietary lipid (1.57%) up-regulated the expressions of genes involved in de - novo lipogenesis in hepatopancreas. Both higher (6.72%) and lower (1.57%) dietary lipid down regulated these genes' expression in muscle. It was found that c-Jun N-terminal kinases (JNK)/mammalian target of rapamycin (mTOR)/sterol regulatory element-binding protein 1c (SREBP-1c) signaling participate in the regulation of de - novo lipogenesis. In conclusion, lipid deposition in abalone was affected by dietary lipid levels through AMPKα2/PPARα and JNK/mTOR/SREBP-1c pathway. • The optimal dietary lipid level for abalone was estimated to be 3.87%. • Dietary lipids increased the lipid deposition in abalone. • 6.72% or 1.57% dietary lipid regulated lipolysis through (ATGL, HSL)/AMPKα2/PPARα pathway. • 6.72% or 1.57% dietary lipid regulated lipogenesis through JNK/mTOR/SREBP-1c pathway. [ABSTRACT FROM AUTHOR]

A 110-day feeding trial was carried out to investigate the impacts of replacing dietary fish meal (FM) with poultry by-product meal (PBM) on growth performance, digestion, gut microbiota, immunity, and disease resistance of abalone Haliotis discus hannai (initial weight: 22.53 ± 0.21 g). The control diet (PBM0) without PBM contained 20% of FM. Based on PBM0, the other four isonitrogenous (about 30% of crude protein) and isolipidic (about 4% of crude lipid) diets were formulated replacing 25, 50, 75 and 100% of FM by PBM (designated as PBM25, PBM50, PBM75 and PBM100), respectively. Every diet was fed to triplicate cages (40 × 35 × 70 cm) with 60 abalones per cage. At the end of the feeding trial, abalones were starved for 3 days and anesthetized with 5% ethanol before sampling. Results indicated that biomass gain of the abalone fed PBM75 (916.71 g) and PBM100 (659.93 g) was significantly lower than that of the abalone fed PBM0 (1222.51 g). Feed conversion ratio of the abalone fed PBM50 (2.93), PBM75 (2.89) and PBM100 (4.04) were significantly higher than that of the abalone fed PBM0 (2.37). The muscle crude protein content of the abalone fed PBM100 (16.01% wet weight) was significantly lower than that of the abalone fed PBM0 (16.67% wet weight). Activities of trypsin and α-amylase in the digestive gland in the PBM100 group (309.21 and 0.064 U/mg prot., respectively) were significantly lower than the PBM0 group (463.57 and 0.078 U/mg prot., respectively). When the substitution levels rose over 50%, expressions of phosphatidylinositol 3 kinase, threonine kinase/protein B, mammalian target of rapamycin and eukaryotic translation initiation factor 4E in muscle were significantly reduced, while 4E binding protein was significantly increased. The most abundant phyla across the abalones' gut were Proteobacteria and Firmicutes. Catalase (from 2.90 to 1.69 U/mL), superoxide dismutase (from 98.93 to 74.39 U/mL), lysozyme (from 345.86 to 247.81 U/mL) and acid phosphatase (from 21.68 to 15.71 U/100 mL) activities in cell-free hemolymph were markedly decreased with substitution level increasing. When the replacement levels rose over 50%, myeloid differentiation primary response gene 88 and tumor necrosis factor α expressions in the digestive gland were markedly upregulated, while β-defensin and mytimacin 6 expressions were markedly downregulated. The cumulative mortality of abalone challenged with Vibrio parahaemolyticus (1.0 × 107 CFU/mL) for 7 days was remarkably increased in the PBM50 (83.49%), PBM75 (89.56%) and PBM100 (100%) groups compared with the PBM0 group (58.82%). In conclusion, 50% of dietary FM could be replaced by PBM without influencing abalone growth. When the replacement level was over 50%, the growth and immunity of abalone were decreased, and the mTOR pathway was negatively affected. • Replacement of dietary fishmeal (FM, 0–20%) by poultry by-product meal (PBM, 0–20.5%) was evaluated in abalone. • The control diet was formulated with 20% of FM and without PBM. • There were no adverse effects on growth when replacement was 50% or less. • Negative effects on growth, immunity and disease resistance were found when PBM replaced more than 50% of FM. • The PBM can be used as an important protein source in the diet for abalone. [ABSTRACT FROM AUTHOR]

The present study investigated the effects of different dietary carbohydrate levels on the growth performance, body composition, glucose/lipid metabolism and insulin signaling pathway in abalone Haliotis discus hannai. Eight experimental diets with graded levels of carbohydrates (18.08%, 22.10%, 26.10%, 29.90%, 34.00%, 38.01%, 41.98% and 45.55%, named as T1, T2, T3, T4, T5, T6, T7 and T8, respectively) were designed to feed abalone (initial weight 22.52 ± 0.05 g) for 110 days. The results showed that the diet containing 38.01% carbohydrate significantly increased the survival rate (SR) and weight gain rate (WGR) of abalone (P < 0.05). Based on the quadratic regression mode of WGR, the optimal dietary carbohydrate level for abalone was estimated to be 37.05%. The activities of intestinal digestive enzymes were significantly increased in the T6 group. Moreover, the expressions of pyruvate kinase (pk) and glucose-6-phosphate dehydrogenase (g6pdh) in digestive glands were up-regulated with the increase of carbohydrate content in diets, while the expression of hexokinase (hk) reached the maximum in the T6 group. The highest expressions of phosphoenolpyruvate carboxykinase (pepck), glucose-6-phosphatase (g6pase) and insulin signaling pathway related genes were found in the T6 group. The expressions of key genes related to lipolysis reached the highest in the T6 group, and then down-regulated with the further increasing dietary carbohydrate levels. The expression of key genes of lipogenesis was up-regulated with the increasing dietary carbohydrate levels. In conclusion, 38.01% of dietary carbohydrate level improved the growth performance of abalone. Dietary carbohydrate levels influenced the glucose and lipid metabolism including insulin signaling pathway. Abalone potentially had the capability to deal with a high-carbohydrate load (45.55%) by increasing glycolysis and decreasing gluconeogenesis. Meanwhile, it promoted lipid synthesis and inhibited lipolysis under high dietary carbohydrate load. • The dietary carbohydrate requirement of abalone was estimated to be 37.05%. • Deficient (18.10%) or excessive (45.55%) dietary carbohydrate content decreased the growth of abalone. • Appropriate dietary carbohydrate content increased the digestive enzyme activities in abalone. • Dietary carbohydrate levels increased the crude lipid content in the soft body of abalone. • Glucose and lipid metabolism including the insulin signaling pathway were regulated by dietary carbohydrate levels. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the replacement of dietary fish meal (FM) with Clostridium autoethanogenum protein (CAP) on abalone Haliotis discus hannai. Five isonitrogenous and isolipidic experimental diets with graded levels of FM replaced by CAP (0, 25, 50, 75 and 100%, respectively) were fed to abalone (initial weight: 21.83 ± 0.25 g) for 110 days. The five diets were named as CAP0, CAP25, CAP50, CAP75 and CAP100, respectively. The results showed that total replacement of dietary FM by CAP did not significantly affect the growth of abalone compared with the control. The highest weight gain rate was observed in the CAP25 group. Compared to the CAP0 group, the CAP25 group also had significantly higher total essential amino acids content in muscle and trypsin activity in digestive gland. The expressions of mammalian target of rapamycin, phosphatidylinositol 3-kinase and threonine kinase/protein B were significantly upregulated, and the expression of AMP-activated protein kinase α2 was significantly downregulated in the muscle of abalone in the CAP25 and CAP50 groups. The crude protein content, hardness, hydroxyproline content, pH value, pyridinium crosslink content, activities of lysyl hydroxylase and prolyl 4-hydroxylase in muscle were significantly elevated in the CAP25 and CAP50 groups. Considering the growth performance, digestion, mTOR pathways and muscle quality, 25% replacement of dietary FM by CAP (4.1% of dietary CAP inclusion level) was recommended for abalone. • Replacement of dietary fish meal (FM) with Clostridium autoethanogenum protein (CAP) on abalone was studied. • Total replacement of dietary FM by CAP did not significantly affect the growth of abalone. • The 25% replacement of dietary FM by CAP (equivalent to 4.1% of CAP in diet) significantly increased the growth of abalone. • Proper dietary CAP inclusion levels (4.1% and 8.15%) had positive effects on mTOR pathways and muscle quality of abalone. • The CAP can be used as an important protein source in the practical diet for abalone. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of replacing fish meal with soybean meal (SBM) on growth performance, immunity, anti-oxidative capacity and mTOR pathway in juvenile abalone Haliotis discus hannai Ino. Five isonitrogenous (about 29% of crude protein) and isolipidic (about 4% of crude lipid) experimental diets with graded levels of fish meal replaced by SBM (0, 25, 50, 75 and 100%, respectively) were fed to abalone (initial body weight: 21.87 ± 0.07 g, initial shell length: 53.18 ± 0.18 mm) for 16 weeks. These experimental diets were named as SBM0, SBM25, SBM50, SBM75 and SBM100, respectively. The results showed that: 1) There was no significant difference in survival of abalone among all the treatments. The highest weight gain rate was found in the SBM50 group, and the group did not significantly differ from those in the SBM75 and SBM100 groups. 2) Replacement of fish meal by SBM linearly and quadratically increased the crude lipid content in muscle of abalone, which reached its highest level in the SBM50 group. 3) Trypsin activity in the digestive gland of abalone fed SBM25 diet was significantly higher than that of other groups. 4) The highest total anti-oxidative capacity and superoxidase activity in digestive gland were found in the SBM50 group. 5) The highest mRNA levels of pi3k and eif-4e , and the lowest level of 4e-bp in muscle were found in the SBM50 group. There was no significant difference in the mRNA level of mtor in the muscle among all the groups. 6). The lowest expression level of nf-κb and the highest expression level of mytimacin 6 in digestive gland of abalone were observed fed SBM50 diet. A significant quadratic trend was found in the mRNA levels of il-16 with increasing levels of dietary SBM. Meanwhile, the mRNA level of β-defensin was linearly decreased after total replacement of fish meal by SBM. Take the growth, antioxidation, immune and mTOR pathway into account, 50% replacement of dietary fish meal by SBM was recommended for abalone. • A control diet was designed to have 20% of fish meal (FM) in the present study. • Compared to the control, 50% replacement of dietary FM by soybean meal (SBM) had significantly higher growth of abalone. • 50% replacement of dietary FM by SBM had positive effects on the mTOR pathway. • Higher replacement level (≥75%) decreased the anti-oxidative capacity of abalone. • Total replacement of dietary FM by SBM had negative effects on the histology of digestive gland. [ABSTRACT FROM AUTHOR]

A 110-day feeding trial was conducted to determine the effects of dietary arginine levels on growth performance, amino acid metabolism, immune response, and disease resistance of abalone Haliotis discus hannai (initial weight: 15.70 ± 0.03 g). Seven isonitrogenous (about 32% of crude protein) and isolipidic (about 3% of crude lipid) diets with 1.17% (the control), 1.36%, 1.68%, 2.19%, 2.47%, 2.82% and 3.43% of arginine were formulated. Each diet was randomly assigned to triplicate cages (5 layers, each layer was 40 cm × 35 cm × 14 cm) with 80 abalones per cage. At the end of the feeding trial, abalones were fasted for 72 h and anesthetized with 5% alcohol. Results showed that final body weight and biomass gain (BG) increased first and thereafter decreased, where the break-points (34.11 g and 934.41 g, respectively) were found in the 1.68% dietary arginine group. Based on the broken-line regression analysis of BG, the optimal dietary arginine level for abalone was estimated to be 1.64% of dry diet. Abalone fed with 2.47% of dietary arginine showed higher crude protein content in the soft body (17.59% wet weight) than other groups. The crude lipid content had a decreasing trend (from 2.02 to 1.28% wet weight) with increasing dietary arginine. The concentration of total free essential amino acids in hemolymph was significantly higher in 1.68% (207.30 μg/mL), 2.19% (199.17 μg/mL) and 2.47% (216.30 μg/mL) dietary arginine groups than that in the control group (P < 0.05). Activities of alanine aminotransferase, total nitric oxide synthase, total anti-oxidative capacity, lysozyme, and the contents of nitric oxide, total protein and albumin were significantly increased as dietary arginine levels increasing from 1.17% to 1.68% and then decreased (P < 0.05). In the digestive gland, the genes expression of nuclear factor erythroid 2-related factor 2, catalase, glutathione peroxidase and Cu/Zn superoxide dismutase were significantly increased in 1.68% dietary arginine group compared with that in the control group (P < 0.05), while the gene expression of kelch-like ECH-associated protein 1 showed an opposite trend. Meanwhile, the gene expression of tumor necrosis factor-α was decreased in 1.36% to 2.82% dietary arginine levels, and the gene expression of Arginase-I was increased in the 1.68% dietary arginine group. The cumulative mortality of abalone challenged with Vibrio parahaemolyticus (1.0 × 107 cfu/mL) for seven days was significantly decreased in the 1.68% dietary arginine group (36.67%) compared with those in the other groups except for the group with 2.19% of dietary arginine. In conclusion, dietary arginine level (1.68%) improved the growth, anti-oxidative capacity, immunity and disease resistance of abalone. • Effects of graded levels of dietary arginine (1.17-3.43%) on abalone were studied. • Based on the broken-line regression analysis of biomass gain, the optimal dietary arginine content was estimated to be 1.64%. • Growth performance and free amino acids concentrations in hemolymph were increased at 1.68% dietary arginine level. • Appropriate dietary arginine level (1.68%) improved immune response through Nrf2 and TLR/NF-κB signaling pathway. • The 1.68% dietary arginine level decreased cumulative mortality after Vibrio parahaemolyticus challenge. [ABSTRACT FROM AUTHOR]