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A total of 6000 shrimp (initial body weight of 0.82 ± 0.02 g) were randomly distributed into twelve concrete pools (4.5 m × 3.5 m × 0.5 m) with 500 shrimp per pool and 3 pools per diet, respectively. Four kinds of isonitrogen and isoenergetic diets were formulated with 0, 0.1%, 0.2% and 0.3% Yucca schidigera extract (YSE), respectively. The experiment lasted 100 d. The results showed as follows: when supplemented with 0.2% dietary YSE, the shrimp weight gain rate significantly increased ( p < 0.05), but no significant change was found in feed conversion ratio, specific growth rate, and survival rate ( p > 0.05). Addition of 0.2% dietary YSE significantly increased the shrimp serum protein content, as well as the activities of acid phosphatase, alkaline phosphatase, nitric oxide synthase, glutamic–pyruvic transaminase, phenol oxidase, and hepatopancreas proteases ( p < 0.05), but did not significantly affect the activities of total superoxide dismutases (T-SOD) and aspartate transaminase ( p > 0.05). In the late culture period (5 th week to 14 th week) the total amount of ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen, and reactive phosphorus in the culture water significantly decreased ( p < 0.05). These results indicated that addition of 0.2% YSE in the diet was beneficial to the growth and nonspecific immunity of white shrimp and water quality. [ABSTRACT FROM AUTHOR]

Abstract: Glutamine synthetase (GS) is a key enzyme involved in nitrogen metabolism and glutamine synthesis. A 1455bp cDNA clone encoding GS was isolated from Litopenaeus vannamei (LvGS, JN620540.1). The sequence consists of a 75bp 5′ untranslated region followed by a 1101bp open reading frame corresponding to 366 amino acids. The encoded protein has a 67% to 93% overall amino acid sequence identity with its counterparts in other various species. A phylogenetic analysis of the GS sequence showed that LvGS clustered with the invertebrate group as expected. qRT-PCR analysis indicated that LvGS was expressed in the stomach, gill, intestine, hepatopancreas, muscle, heart, and eyestalk. The profile of LvGS was up-regulated in the stomach, gills, intestines, and hepatopancreas after 48h of exposure to dilute seawater (4ppt). The mRNA levels of LvGS in the hepatopancreas significantly increased 2.9-fold after 3h to 3d of exposure to dilute seawater (P <0.05). The LvGS activity and glutamine in the hepatopancreas increased after 3h to 3d and then decreased after 7d to 20d of exposure to dilute seawater. However, the hemolymph total protein and ammonia decreased after 3h to 3d, and then increased after 7d to 20d. The hemolymph urea and uric acid significantly increased after 3h to 12h of exposure to dilute seawater. L. vannamei fully acclimated to a low salinity environment within a week. LvGS can participate in physiological osmotic adaptation to hypo-osmotic water and aid L. vannamei in resisting acute salinity changes via the manipulation of nitrogen metabolism. [Copyright &y& Elsevier]

• Three Bacillus species' (B. spp.) effects in Sillago sihama (S. sihama) were studied. • B. spp. improved growth, immune and antioxidant activities of S. sihama. • B. spp. enhanced the abundance of bacteria considered beneficial for gut health. • Dietary B. spp. inclusion enhanced the resistive capacity of S. sihama. • Paenibacillus polymyxa inclusion showed the best probiotic effects in S. sihama. The present study investigated the effects of three probiotic strains viz. Bacillus coagulans ATCC 7050 (BC), Bacillus licheniformis ATCC 11946 (BL), and Paenibacillus polymyxa ATCC 842 (PP) on growth, immune response and antioxidant enzyme activities, intestinal microbiota, and resistance against isolated Vibrio harveyi HY99 in juvenile northern whiting fish, Sillago sihama. Three hundred and sixty juvenile S. sihama fish (initial weight 0.67 ± 0.002 g) stocked in 12 fiberglass tanks were fed with basal diet void of probiotic inclusion (control, B0), and BC, BL, and PP at 1012 CFU kg−1 feed. After the 56-day experimental period, regardless of the probiotic strain used, there were significant increase (P < 0.05) in the survival rate, final weight, weight gain rate, specific growth rate, protein efficiency ratio, hepatosomatic index, viscerosomatic index; crude protein, crude lipid content in the whole body; superoxide dismutase, alkaline phosphatase, acid phosphatase, glutathione peroxidase levels in the liver and a significant decrease in the feed conversion ratio; aspartate aminotransaminase, alanine aminotransaminase, malondialdehyde levels in the liver (P < 0.05) of the probiotic treated group than the untreated. Congruently, a significantly high (P < 0.05) intestinal villi height, villi width, crypt depth, and muscle thickness, were detected in the probiotic treated groups than the control with the PP group experiencing the highest. Probiotics' supplementations in diets also revealed a significantly high (P < 0.05) relative abundance of Proteobacteria than the control group contrast to as observed in Firmicutes. Additionally, the PP and BL groups were found to have a significant (P < 0.05) increase in Bacteroidetes and Gemmatimonadetes abundance than the BC and B0 groups. At the genus level, all fish supplemented with probiotic diet had a significantly (P < 0.05) lower abundance of some purportedly pathogenic genera such as Enterovibrio and Shewanella as well as significantly (P < 0.05) higher abundance of purportedly beneficial genera such as Ruegeria , Phyllobacterium , Sphingomonas , and Lactobacillus. Challenge with V. harveyi in a 14-day study revealed highly significant (P < 0.05) protection of probiotic groups than the control; thus, the B0, BC, BL, and PP groups obtained 78 %, 58 %, 53 %, and 43 % cumulative mortality, respectively. Collectively, these results suggest that dietary supplementation of probiotics viz. BC, BL, and PP at 1012 CFU kg−1 feed exert positive effects; however, PP at a similar dosage is recommended due to its highest improvement in the growth, immune response, antioxidant activities, intestinal health, and disease resistance against V. harveyi. [ABSTRACT FROM AUTHOR]

• The high survival rate (≥95%) and weight gain rate confirm the potential of artificial culture in S. sihama. • Vitamin E requirement of juvenile S. sihama was estimated to be 100.37 mg/kg based on the growth performance. • Vitamin E improved the oxidation resistance related to upregulated Nrf2 and Keap1 expression in juvenile S. sihama. • The variation of antioxidant indices against dietary vitamin E level was tissue-specific. The influence of dietary vitamin E supplementation on growth, immunity and oxidation resistance related to nuclear factor-erythroid 2-related factor 2 (Nrf2)/Kelch-like epichlorohydrin associating protein 1 (Keap1) signalling molecules in juvenile Sillago sihama (2.14 ± 0.02 g, initial mean weight ± SD) was investigated. Altogether, 720 fish were divided into six groups with four repetitions (30 fish each) and fed six diets containing graded concentrations of vitamin E including 4, 14, 22, 47, 95 and 198 mg/kg respectively for eight weeks. Compared with the control, results suggested that dietary vitamin E had the following effects: increased weight gain rate (WG), protein efficiency ratio (PER) and feed intake (FI), and decreased feed conversion ratio (FCR) (P < 0.05); increased hepatic alkaline phosphatase (AKP) activity, complement 3 (C3) and immunoglobulin M (IgM) concentrations (P < 0.05); increased glutathione-S-transferase (GST), catalase (CAT) and glutathione peroxidase (GPx) activities; decreased malondialdehyde (MDA) concentration in the liver; increased copper-zinc superoxide dismutase (CuZnSOD), GST, CAT and GPx activities in the intestine (P < 0.05); and upregulated Nrf2, Keap1, CAT, GST, GPx, glutathione reductase (GR), CuZnSOD and manganese superoxide dismutase (MnSOD) gene expression in the liver and intestine (P < 0.05). Based on regression analysis for WG, the dietary requirement of vitamin E for juvenile S. sihama was estimated to be 100.37 mg/kg. [ABSTRACT FROM AUTHOR]