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Staphylococcus aureus is a common Gram-positive pathogen that causes food poisoning and foodborne illnesses. In this study, a peptide-designated NGJ1D (GAPNDLTARFIAKK) was found among 8 peptides in the fermentation broth of Lacticaseibacillus paracasei. NGJ1D had a minimum inhibitory concentration (MIC) of 62.5 μg/mL against Staphylococcus aureus and could kill the bacteria within 3 h. In a mimicked bacterial cell membrane environment, NGJ1D could change its secondary structure from a random coil to an α-helix to increase its membrane permeability and subsequent interaction with bacteria genomic DNA. Further analysis using SDS–polyacrylamide gel electrophoresis, ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS), and molecular docking revealed that NGJ1D affects the DNA-binding protein HU of S. aureus to interfere with DNA synthesis. These results indicate that novel peptides with antimicrobial potential, such as NGJ1D, could be identified in fermentation broths and can be used for application in food preservation and the prevention and treatment of infections caused by S. aureus. [ABSTRACT FROM AUTHOR]

This study aimed to improve bacterial inhibition in Pickering emulsions during storage using antimicrobial peptides. A peptide (ARHQGVMVGMGQK), designated SA6, isolated from the broth of salt-fermented shrimp (Penaeus vannamei). Peptide SA6 had a minimum inhibitory concentration (MIC) of 15.6 μg/mL against Staphylococcus aureus. The mean particle size of SPI-SA6 particles (417.4 nm) was significantly smaller compared with soybean isolate protein (SPI) (463.3 nm). Moreover, the polydispersity index (PDI) decreased with increasing peptide concentration, while the particles were stabilized by hydrogen bonding. SPI-SA6 Pickering emulsions were stable for the entire storage period (7 d) and had lower creaming index and droplet size compared with SPI Pickering emulsions. Further, SPI-SA6 Pickering emulsion could effectively inhibit bacterial growth and disrupt bacterial cell membrane structure, to significantly decrease bacteria (S. aureus) numbers to 2.83 CFU/mL during storage and therefore extending the inhibition time. Collectively, peptide SA6 could stabilize Pickering emulsion while exerting antibacterial effects. [ABSTRACT FROM AUTHOR]

Current cancer treatment regimens such as chemotherapy and traditional chemical drugs have adverse side effects including the appearance of drug-resistant tumor cells. For these reasons, it is imperative to find novel therapeutic agents that overcome these factors. To this end, we explored a cationic antimicrobial peptide derived from Litopenaeus vannamei hemocyanin (designated LvHemB1) that induces cancer cell death, but sparing normal cells. LvHemB1 inhibits the proliferation of human cervical (HeLa), esophageal (EC109), hepatocellular (HepG2), and bladder (EJ) cancer cell lines, but had no significant effect on normal liver cell lines (T-antigen-immortalized human liver epithelial (THLE-3) cells). In addition to its antiproliferative effects, LvHemB1 induced apoptosis, by permeating cells and targeting mitochondrial voltage-dependent anion channel 1 (VDAC1). Colocalization studies revealed the localization of LvHemB1 in mitochondria, while molecular docking and pull-down analyses confirmed LvHemB1-VDAC1 interaction. Moreover, LvHemB1 causes loss in mitochondrial membrane potential and increases levels of reactive oxygen species (ROS) and apoptotic proteins (caspase-9, caspase-3, and Bax (Bcl-2-associated X)), which results in mitochondrial-mediated apoptosis. Thus, peptide LvHemB1 has the potential of being used as an anticancer agent due to its antiproliferation effect and targeting to VDAC1 to cause mitochondrial dysfunction in cancer cells, as well as its ability to induce apoptosis by increasing ROS levels, and the expression of proapoptotic proteins. [ABSTRACT FROM AUTHOR]

Commonly used aquatic feed naturally contains low-level or no hydroxyproline (Hyp). This study was conducted to evaluate the effects of dietary Hyp inclusion on growth performance, body composition, amino acid profiles, blood biochemistry, and the expression of target of rapamycin (TOR) pathway-related genes in juvenile Nibea diacanthus. Fish with similar size (initial body weight, 133.00 ± 2.14 g) were fed six isonitrogenous and isolipidic practical diets supplemented with graded levels of Hyp (0, 5, 10, 15, 20, and 25 g kg−1 of dry matter) for 8 weeks. The results indicated that growth performance and feed utilization were improved with increased levels of dietary Hyp (P < 0.05), and the optimum amount of dietary Hyp estimated from SGR as 16.6 g kg−1. The crude protein of whole body and swim bladder and the amino acid composition of muscle and swim bladder were significantly (P < 0.05) affected by the addition of dietary Hyp, which reflects the important role of feed composition in animal body composition. In addition, the expression levels of mammalian target of rapamycin (TOR) and ribosomal protein S6 kinase1 (S6K1) genes in the liver, muscle, and swim bladder increased with increasing Hyp content of diets, while the mRNA expression level of eukaryotic translation initiation factor 4E-binding protein (4E-BP) gene in these tissues decreased. These results indicated that Hyp improved fish growth and the ability to synthesize proteins, most likely through the TOR pathway. It is suggested that dietary Hyp supplementation is particularly necessary for application in aquatic feed. [ABSTRACT FROM AUTHOR]

A lipase gene was cloned from Trichosporon fermentans Y3, subcloned into pPICZαA, and then expressed in Pichia pastoris X33. The lipase (lipRT), which was obtained using a 50-L bioreactor, had maximum activity of 6000 U/mL. It had an optimum pH 8.0 and remained stable between pH 3.0 and 11.0, while its optimum temperature was 45 °C, maintaining more than 55% of optimum activity between 20 and 35 °C. To evaluate the potential application of lipRT as an aquafeed additive for juvenile grouper (Epinephelus coioides), fish with initial weight 13.31 ± 0.26 g were randomly divided into 12 sea cages and fed five formulated diets (labeled diets 1 to 4). Diets 1–4 were formulated to include 8% crude lipid and serial levels of lipRT (0 U/kg, 50 U/kg, 500 U/kg, and 1000 U/kg). The results showed that WG, FE, and PER of fish as well as ACH50, LSZ, and O2− production ratio in serum of fish on diets 3 and 4 were significantly (P < 0.05) higher than those on diets 1 and 2. The present data suggests that lipRT could improve the utilization of lipid and some nonspecific immunological parameters, and therefore could potentially be used as an aquafeed additive. [ABSTRACT FROM AUTHOR]

Amino acids can act as signaling molecules in protein synthesis and animal growth by regulating several genes in the target of rapamycin (TOR) pathway. An 8-week feeding trial was conducted to examine the effects of dietary proline on growth performance, body composition, amino acid profiles, blood-biochemistry and expression of TOR pathway-related genes in juvenile Nibea diacanthus. Fish (450 juvenile N. diacanthus) were assigned to six dietary proline supplementation groups (0, 2.5, 5, 7.5, 10 and 12.5 g kg−1 of dry diet). The results revealed that the growth performance and feed utilization of N. diacanthus were not significantly improved with dietary proline level (P > 0.05). Whole-body crude protein and some amino acids in muscle tissue were significantly (P < 0.05) affected by the supplemental dietary proline, while the levels of hepatic GOT and GPT increased significantly (P < 0.05) with increasing levels of dietary proline. The transcript level of TOR in muscle was significantly affected by dietary proline level, while the mRNA levels of 4EBP, S6K1, TSC and GTPBP in muscle were relatively unaffected. In conclusion, our results indicate that (1) dietary proline promotes protein synthesis, and (2) proline may promote protein synthesis by regulating the transcription of TOR but not 4EBP, S6K1, TSC and GTPBP. [ABSTRACT FROM AUTHOR]

Singapore grouper iridovirus (SGIV) is a lethal grouper virus containing 162 predicted ORFs. Previous proteomic studies led to identification of 73 SGIV structural proteins. Here, SDS-assisted tube-gel digestion and DOC-assisted in-solution digestion coupled with LC-ESI-MS/MS were applied to further profile the SGIV structural proteome. We identified a total of 90 SGIV structural proteins including 24 newly reported proteins. Additionally, several PTMs were identified, including 26 N-terminal acetylated proteins, three phosphorylated proteins, and one myristoylated protein. Importantly, 47 of the proteins that were identified are predicted to contain conserved domains. Our work greatly expands the repertoire of the SGIV structural proteome and provides more insight into the biology of SGIV. [ABSTRACT FROM AUTHOR]

The black sea bream, Acanthopagrus schlegelii, an important marine species of high economic value and excellent meat quality, has suffered great losses due to disease in high-density aquaculture. The seaweed, Sargassum horneri (SH), which has various biologically active substances beneficial human and animal health, may serve as an immunostimulant in the aquaculture industry. The present study aimed at evaluating the effects of dietary S. horneri on growth performance, serum biochemical parameters, hepatic antioxidant status, and immune responses of juvenile A. schlegelii. Four-hundred and eighty fingerlings with approximate mean body weight 5.6 ± 0.1 g were randomly distributed into four experimental groups in triplicates. Each group was stocked with 40 fish and fed isonitrogenous (42% crude protein) and isolipid (12% crude lipid) experimental diets containing either 0% SH (control), 3% SH, 6% SH, or 9% SH for 8 weeks. Compared with the control group, final body weight, weight gain rate, and specific growth rate were improved significantly with 6% SH supplemented group (P < 0.05). Serum total protein and globulin contents in the S. horneri supplemented groups were significantly higher than those of the control group (P < 0.05). However, the levels of total cholesterol and triglyceride decreased with increasing dietary S. horneri levels, particularly in the 9% group (P < 0.05). Serum lysozyme, acid phosphatase, alkaline phosphatase, complement 3, and complement 4 levels were significantly higher in the 6% SH group with relative to the control group (P < 0.05). Apart from a significant decrease in malondialdehyde, the total antioxidant capacity, superoxide dismutase, and catalase activities in the liver of the S. horneri supplemented groups were significantly higher than those of control group (P < 0.05). The mRNA expression levels of interleukin-1β, interleukin-8, and tumor necrosis factor in the liver of fish significantly increased with S. horneri diets compared with control (P < 0.05), except for interleukin-8 in the 3% SH group. In conclusion, these results indicated that dietary S. horneri supplementation could promote growth performance, improve hepatic antioxidant status, and enhance immune ability of A. schlegelii, with an optimum supplemental level of 6% recommended in this study. [ABSTRACT FROM AUTHOR]

Ammonia is an important environmental toxic pollutant that represents a biochemical and physiological hazard to living organisms, especially in intensive culture systems with high stocking density. This study aimed at evaluating the protective effects of Sargassum horneri (SH) on ammonia stress in black sea bream. Four hundred and eighty fingerlings with approximate mean body weight 12.0 ± 0.1 g were randomly distributed into four experimental groups in triplicate. Each group was stocked with 40 fish and fed with isonitrogenous (42% crude protein) and isolipid (12% crude lipid) experimental diets containing either 0% SH (control), 3% SH, 6% SH, or 9% SH in the feed. At the end of 8 weeks of experimental feeding, fish were exposed to ammonia for 24 h. The results indicated that ammonia stress led to an increase in oxidative stress as shown by elevation in the levels of cortisol and liver lipid peroxidative damage markers as well as decrease in antioxidant biomarkers. Furthermore, humoral immunity was suppressed during the stress period. However, fish supplied with S. horneri had significant improvement in immune response, antioxidant capacity, and resistance against ammonia stress, particularly in the 6% SH group. Therefore, dietary S. horneri supplementation at an optimum level of 6% could increase the resistance of juvenile black sea bream to ammonia-induced stress. [ABSTRACT FROM AUTHOR]

Hemocyanin, the multifunctional glycoprotein in the hemolymph of invertebrates, can generate various antimicrobial peptides (AMPs). Given the rising interest in the use of natural therapeutic agents such as AMPs, alternative and more efficient methods for their generation are being explored. In this work, free online software was first applied to predict the generation of antimicrobial peptides from the large subunit of Litopenaeus vannamei hemocyanin. Twenty potential antimicrobial peptides ranging from 1.5 to 1.9 kDa were predicted, five of which had α-helical structures and were selected for antibacterial activity testing. The results indicated that these five peptides had antibacterial activity against seven different bacteria. Of the five peptides, one peptide, designated L1, had the strongest antibacterial activity against both Gram-negative and Gram-positive bacteria. Moreover, CD and NMR data showed that L1 had both α-helical and β-turns structural composition, and that these structures were essential for L1’s antibacterial activity. Furthermore, SEM analysis revealed that peptide L1 had broad-spectrum activity against both Gram-positive and Gram-negative bacteria, as it could destroy the bacterial cell walls and kill the bacteria. Thus, L1 is a very potent antimicrobial peptide that can be exploited and used in antibacterial therapeutics. [ABSTRACT FROM AUTHOR]