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关键词： Cloning   Sequencing   Genetic characterization   AutoDock Vina  

摘要： This study employed mesophilic Bacillus subtilis RTS strain isolated from soil with high xylanolytic activity. A 642 bp (xyn) xylanase gene (GenBank accession number MT677937) was extracted from Bacillus subtilis RTS and cloned in Escherichia coli BL21 cells using pET21c expression system. The cloned gene belongs to glycoside hydrolase family 11 with protein size of approximately 23 KDa. The recombinant xylanase showed optimal enzymeactivity at 60 degrees C and at pH6.5. Thermostability of recombinant xylanase was observed between the temperature range of 30-60 degrees C. Xylanase also remained stable in different concentration of various organic solvents (ethanol, butanol). This might be due to the formation of protein/organic solvent interface which prevents stripping of essential water molecules from enzyme, thus enzyme conformation and activity remained stable. Finally, the molecular docking analysis through AutoDock Vina showed the involvement of Tyr 108, Arg140 and Pro144 in protein-ligand interaction, which stabilizes this complex. The observed stability of recombinant xylanase at higher temperature and in the presence of organic solvent (ethanol, butanol) suggested possible application of this enzyme in biofuel and other industrial applications. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Lipid classes   Fatty acids   Histology   Large nuclei   Plasma biochemistry   Nutrition  

摘要： The study examined the interactive effects of choline content (supplied as choline chloride salt (CC);no added CC, 3.0, or 6.0 g CC kg(-1) diet) and water temperature (16 degrees C vs 24 degrees C) on liver lipid composition, liver histology and plasma biochemistry. Liver and plasma samples were collected from juvenile yellowtail kingfish (Seriola lalandi;YTK;156 g body weight), fed fishmeal-based practical diets, at the conclusion of an eight-week feeding experiment. The results showed that higher liver lipid content at 24 degrees C was due to greater triacylglycerol (TAG) accumulation. Liver phospholipids content remained similar regardless of CC supplementation and temperature (P > 0.05). As expected, liver phospholipids were mainly composed of phosphatidylcholine (PC);however, in most cases liver phospholipids were almost completely made up of PC. Phospholipid classes were also not significantly affected by CC supplementation and temperature. The results indicate that these lipid classes were tightly regulated in the liver of juvenile YTK. Fatty acids composition among TAG, FFA, and phospholipids fractions were different;however, within the phospholipids fraction, the long chain polyunsaturated fatty acids (LC-PUFA) proportion in the liver of YTK remained unchanged regardless of treatments. In general, histological examination did not show severe lesions in fish livers across all treatments. Fish also had significantly more hepatocytes with large nuclei at 16 degrees C than at 24 degrees C which is a response that requires further research. Plasma analytes were profoundly affected by temperature rather than by CC supplementation;however, there is no strong evidence indicating compromised health in fish reared at either temperature. This study demonstrates that fish fed fishmeal-based practical diets generally had normal looking livers;nevertheless, some liver and plasma health indicators can be affected in juvenile YTK reared at sub-optimal temperatures and fed

关键词： Quorum quenching probiotic   Bacillus   Performance   Survival   Asian seabass   Vibrio harveyi  

摘要： The use of probiotics is a promising and increasingly common strategy to maintain a healthy farming environment in an eco-friendly and sustainable manner. The goal of this study was to investigate the possible effects of dietary supplementation with autochthonous quorum quenching (QQ) probiotics on growth, digestive enzymes activity, haemato-biochemical responses, gut microbial communities and resistance against Vibrio harveyi in Asian seabass. Asian seabass (75 +/- 0.6 g and 15.5 +/- 0.3 cm) were fed with basal diet (control groups) and basal diet containing 1 x 10(9) CFU per g Bacillus thuringiensis QQ1 or Bacillus cereus QQ2 for 6 weeks. Feeding with diets supplemented with QQ probiotics for 35 days (pre-infection period) resulted in a significant (p < 0.05) alteration of the growth parameters (RGR, FCR, SGR, PER, FER and FI) and digestive enzymes activity (alpha-amylase, total protease, lipase, trypsin, alkaline phosphatase, T/C and A/T). Hematocrit (Hct) and total leucocyte count (TLC) were significantly (p < 0.05) elevated in fish fed with QQ1. Respiratory burst activity (RBA) likewise significantly (p < 0.05) increased in the probiotic groups relative to the control groups. Moreover, a significant decrease (p < 0.05) in the level of serum total cholesterol was observed in fish fed with probiotic. QQ1 and QQ2 were able to colonize the host's intestine at high number after 5 weeks. Hct and RBA in QQ1 and QQ2, globulin in QQ2 and TLC in QQ1 were significantly (p < 0.05) promoted compared to the positive control (PC) after infection with Vibrio harveyi (day 42). Serum triglycerides, cholesterol, alkaline phosphatase (ALP), alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT) and lactate dehydrogenase (LDH) were significantly (p < 0.05) lower in the probiotic treatments than the PC group after infection. QQ probionts significantly (p < 0.05) improved the cumulative survival of Asian seabass against V. harveyi. According to these findings, we suggest

关键词： Grass carp   Microbial spoilage   Biochemical changes   Amino acid deamination   Amino acid decarboxylation   Chilled storage  

摘要： This study aimed to reveal amino acid deamination and decarboxylation activities of spoilage microbiota in chill stored grass carp fillets. Results showed that microbial deamination activities of umami/sweet-taste amino acids were higher than that of bitter-taste amino acids. The total deamination activity of tested amino acids decreased during the late period of storage, which inhibited the increase of ammonia in fish flesh. Microbial decarboxylation activity of ornithine was much higher than lysine and histidine, which was consistent with the rapid increase of putrescine in fish fillets. Meanwhile, putrescine could be produced in large quantities through arginine deiminase pathway of spoilage bacteria. Glucose utilization by spoilage microbiota was active during the late period of storage, which was consistent with the rapid consumption of lactate and total sugar in fish flesh. Overall, results of this study could be beneficial for revealing fish spoilage mechanisms and providing theoretical guidance for developing fish preservation technologies.

关键词： pacama   Welfare   Anesthetic   Carnivorous fish  

摘要： This study evaluated the effects of the essential oil of Ocimum gratissimum L. (EOOG) on water quality, blood characteristics and tissue damage during transport of Lophiosilurus alexandri. One hundred and sixty juveniles of L. alexandri (123.44 +/- 1.95 g and 23.71 +/- 1.95 cm) were fasted for 24 h before transportation. Fish were then submitted to one of three treatments of transport water with five replicates each: 0 (control), 5 and 10 mg/L EOOG. The animals were transported for 4 h in plastic bags at a density of 1 juvenile/L and 10 animals per bag. The ventilatory frequency of one fish from each bag was determined after 3 h of transport by direct observation and counting of opercular beats. Blood, brain and liver samples were collected prior to (basal group) and at the end of transport from 10 animals each. Blood aliquots were used to determine hematocrit and hemoglobin, total plasma protein, glucose, aspartate aminotransferase and alanine aminotransferase levels. Samples of liver and brain were used to determine parameters and oxidative stress (reactive oxygen species, glutathione peroxidase, superoxide dismutase, glutathione S-transferase, lipid peroxidation and protein carbonyl formation). No mortality was observed 24 h after transport. The addition of EOOG to transport water appeared to reduce animal metabolism, thus ensuring higher dissolved oxygen and lower ammonia levels. Juveniles transported with 10 mg/L EOOG also had reduced opercular beats, lower levels of hemoglobin and blood aspartate aminotransferase and glucose. This concentration also reduced lipid and protein oxidation levels in tissues, thereby avoiding lipid peroxidation and the formation of carbonyl protein. The use of 10 mg/L EOOG during transport promotes a sedative effect in L. alexandri, with reduced oxygen consumption, ammonia excretion and biochemical changes and enhanced protection against oxidative damage.

关键词： Avocado   Oil accumulation   Tissue-specific   Transcription factor   Long non-coding RNA  

摘要： The fatty acids in avocado mesocarp and seed are crucial constituents and possess the critical influence in commercializing for fresh-eating consumption and industrially oil processing. Hence, plant physiologists express an interest in better understanding tissue-specific oil biosynthesis and the associated regulatory network between the developing avocado (Persea americana) mesocarp and seed, which will contribute to improving the quality and utility of avocado fruits in food and industrial processing. The results revealed the ever-increasing and fluctuating trends in the oil accumulation in the developing avocado mesocarp and seed, respectively. Additionally, striking differences in the lipid droplets between the developing mesocarp and seed were revealed in confocal microscopy images. The tissue-specific transcription of lipid-related genes contributing to fatty acid synthesis, triacylglycerol assembly, and triacylglyceml storage was examined, and four highly transcribed lipid-related genes (PaFAB2, PaACP4-2, PaDGAT2, and PaFAD2-1) involved in FA synthesis and TAG assembly were indicative of the key roles in oil accumulation variation between the developing avocado mesocarp and seed. A weighted gene co-expression network analysis uncovered two highly expressed lipid-related hub transcription factors (PaPBS1-1 and PaRAP2-3) that each played a crucial part in oil biosynthesis regulatory network in avocado mesocarp and seed, respectively. Moreover, our data also revealed that five highly expressed cis-acting lncRNAs (PB.19359.1, PB.6205.1, PB.4443.3, PB.12340.3, and PB.19743.2) may give rise to the observably differences in the oil accumulation between the developing mesocarp and seed. Our data may be useful for characterizing tissue-specific oil accumulation at the multifaceted levels, thereby identifying four functional genes, two transcription factors, and five lncRNAs for improving the oil production of related plant species.