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A 120-day feeding trial was conducted to investigate the effects of relative higher and lower dietary protein levels on the growth, immunity and anti-stress of abalone Haliotis discus hannai fed diets with 17.64% (low), 30.49% (normal) and 43.27% (high) of proteins, respectively. The results showed that compared with 30.49% of dietary protein, 17.64% and 43.27% of dietary protein levels significantly decreased the weight gain rate and the activities of α-amylase, trypsin, alanine aminotransferase and aspartate aminotransferase in the hepatopancreas and serum of abalone (P < 0.05). Abalone fed 30.49% of dietary protein had the highest activity of superoxidase, acid phosphatase, alkaline phosphatase, lysozyme and the total anti-oxidative capacity, and the lowest content of malondialdehyde in the serum and hepatopancreas (P < 0.05). The gene expressions of TOR, S6k, Bcl-2, IκB, NfκB, TNF-α and Nrf 2 were significantly up-regulated in the group with 30.49% of dietary protein (P < 0.05). Pathological abnormalities in hepatocyte cells of abalone were found in the groups with 17.64% and 43.27% of dietary protein. Meanwhile, accumulative mortalities of abalone after the Vibrio parahaemolyticus challenge test and heat stress test were significantly increased within these two groups (P < 0.05). In conclusion, the excessive (43.27) or deficient (17.64) dietary protein levels depressed the growth and immunity of abalone. Combined with the stress tests results, 17.63% or 43.27% of dietary protein contents are not recommended to the abalone facing the stress of vibriosis or high-water temperature (≥28 °C). • Abalones were fed diets with 17.64% (low), 30.49% (normal) and 43.27% (high) of proteins, respectively, for 120 days. • Relative low or high dietary protein contents decreased the growth of abalone. • Normal dietary protein had the higher anti-oxidation and immune related enzyme activities and TOR expressions. • 17.63% or 43.27% of dietary protein contents are not recommended to the abalone facing the environmental stress. [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]

The forkhead box O (FoxO) subfamily is a member of the forkhead transcription factor family. It has regulation functions in glucose metabolism in mammals and fish. In the present study, a gene of the foxo homolog in abalone Haliotis discus hannai was cloned. A conservative forkhead (FH) domain and a transactivation (FoxO-TAD) domain were identified. Abalone foxo-specific siRNA (small interfering RNA) was injected to investigate the functions of foxo on glucose metabolism. Knockdown of foxo inhibited expression of phosphoenolpyruvate carboxykinase (pepck) and significantly increased expressions of hexokinase (hk) and pyruvate kinase (pk), but it failed to inhibit the relative mRNA level of glucose-6-phosphatase (g6pase). Then, a 100-day feeding trial was conducted to investigate the response of foxo and glucose metabolism in abalone fed with 1.57% (LFD, low-fat diet), 3.82% (MFD, middle-fat diet) and 6.72% (HFD, high-fat diet) of dietary lipid, respectively. The insulin-signaling pathway (AKT) was depressed and FoxO was activated by the HFD, but it did not inhibit glycolysis (hk) or improved gluconeogenesis significantly (pepck and g6pase). At the same time, impaired hepatopancreas glycogen storage raised hemolymph glucose levels. In conclusion, abalone foxo can be regulated by dietary lipid and can regulate gluconeogenesis or glycolysis in response to changes of dietary lipid levels, in which glycogen metabolism plays an important role. [ABSTRACT FROM AUTHOR]

A 110-day feeding trial was conducted to investigate the effects of dietary chromium (Cr) on the growth performance, immune response, anti-oxidative capacity, stress resistance, flesh quality of abalone Haliotis discus hannai. Seven isonitrogenous and isolipidic experimental diets were formulated with graded levels of Cr (0.04, 0.67, 1.21, 1.58, 2.21, 2.72 and 3.33 mg/kg) from Cr yeast. The results showed that weight gain rate (WGR) was highest in the group with 1.21 mg/kg of dietary Cr. Based on the broken-line regression analysis for WGR, the dietary Cr requirement of abalone was estimated to be 1.32 mg/kg. With the increase of dietary Cr level from 0.04 to 1.21 mg/kg, the total anti-oxidative capacity and lysozyme activity in the cell-free hemolymph were increased and then decreased when the dietary Cr level exceeded 1.21 mg/kg. After the challenge of Vibrio parahaemolyticus , the cumulative mortality of abalone was significantly decreased in the group with 1.21 mg/kg of dietary Cr compared with that in the control group. Meanwhile, after the heat stress test, the cumulative mortality of abalone was significantly reduced in the groups with 1.58, 2.21 and 2.72 mg/kg of dietary Cr compared with that in the control group. The liquid and water loss of foot muscle were significantly increased in the groups with 2.72 and 3.33 mg/kg of dietary Cr. With the increase of dietary Cr levels, the hardness of foot muscle was significantly elevated. The chewiness of foot muscle was significantly increased with the increase of dietary Cr level from 0.04 to 1.21 mg/kg, and thereafter showed no significant difference when dietary Cr exceeded 1.21 mg/kg. In conclusion, based on the WGR, dietary Cr requirement of abalone (initial weight: 22.31 ± 0.31 g) was estimated to be 1.32 mg/kg. Appropriate dietary Cr levels (1.21–1.58 mg/kg) had positive effects on growth performance, immune response, anti-oxidation, anti-stress and flesh quality of abalone. Overhigh dietary Cr level (2.72–3.33 mg/kg) decreased the flesh quality. Excessive dietary Cr level (3.33 mg/kg) had a negative effect on the health of abalone. • The dietary chromium requirement of abalone was estimated to be 1.32 mg/kg. • Overhigh dietary Cr level (2.72–3.33 mg/kg) decreased the flesh quality. • Excessive dietary Cr level (3.33 mg/kg) had a negative effect on the health of abalone. • Chromium could accumulate in the muscle of abalone. [ABSTRACT FROM AUTHOR]

A 115-day feeding trial was conducted to investigate the effect of dietary carbohydrate and vitamin D 3 levels, and their interactions on growth performance, body composition, insulin signaling pathway and glucose metabolism in juvenile abalone Haliotis discus hannai (initial body weight: 2.06 ± 0.01 g). Nine experimental diets in a 3 × 3 two-factor design were formulated with different carbohydrate levels (27.5%, 32% and 36.5%) and vitamin D 3 levels (0, 1000 IU/kg and 5000 IU/kg). Results showed that the highest specific growth rate (SGR) of abalone was observed in the treatment with 36.5% of dietary carbohydrate and 1000 IU/kg of vitamin D 3. The serum glucose, body crude lipid and muscle glycogen contents of abalone significantly increased with increasing dietary carbohydrate levels (P < 0.05). Diet with 1000 IU/kg of vitamin D 3 significantly reduced the serum glucose and body crude lipid content (P < 0.05). Significant interactions between dietary carbohydrate and vitamin D 3 were observed in SGR and crude lipid content (P < 0.05). Diet with 36.5% carbohydrate up-regulated the expression of pyruvate kinase, glucose-6-phosphate dehydrogenase (G6PDH), insulin receptor (IR), insulin receptor substrate (IRS), protein kinase B (Akt), glycogen synthase and glycogen phosphorylase (PYG), whereas decreased the phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G6P) and glycogen synthesis kinase-3β. Diet with 1000 IU/kg of vitamin D 3 significantly up-regulated the hexokinase, IR, IRS, Akt and glucose transporter 1 mRNA levels, whereas decreased the G6PDH (P < 0.05). The interaction between dietary carbohydrate and vitamin D 3 were significant on PEPCK, G6P, G6PDH and PYG mRNA levels (P < 0.05). In conclusion, dietary carbohydrates and vitamin D 3 could affect glucose metabolism by regulating glycolysis, gluconeogenesis and pentose phosphate pathway in abalone. Besides, they triggered the insulin signaling pathway, and further influence glucose transport and glycogen synthesis, which could promote the utilization of carbohydrate in abalone. • 36.5% of dietary carbohydrate and 1000 IU/kg of vitamin D 3 were beneficial to the growth of abalone. • Appropriate dietary vitamin D 3 content promotes glycolysis and inhibits pentose phosphate pathway. • Appropriate dietary carbohydrate levels promote glycolysis, glycogenesis and pentose phosphate pathways. • Interaction between carbohydrates and vitamin D 3 activates the insulin signaling pathway. [ABSTRACT FROM AUTHOR]