Transcriptomic Analysis of Drug-Resistance Acinetobacter baumannii under the Stress Condition Caused by Litsea cubeba L. Essential Oil via RNA Sequencing.

Litsea cubeba L. essential oil(LCEO) can affect the growth of drug-resistance bacteria. However, research on stress response of drug-resistant A. baumannii under sub-lethal LCEO concentrations had been limited so far. Therefore, transcriptomic analysisof A. baumannii under 1/2 minimum inhibitory concentration (MIC, 0.54 mg/mL) of LCEO was performed. Results of transcriptomic analysis showed that 320/352 genes were significantly up/down-regulated, respectively, in LCEO-treated A. baumannii. Both up and down-regulated genes were significantly enriched in three GO terms (oxidation-reduction process; oxidoreductase activity; oxidoreductase activity, acting on the CH-CH group of donors), which indicated that the redox state of A. baumannii was significantly affected by LCEO. LCEO may also inhibit aerobic respiration, synthesis of ketone bodies and the metabolism of some amino acids while, meanwhile, promoting fatty acid degradation of A. baumannii according to Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. The permeability and the stress of cell membrane of A. baumannii were significantly affected by LCEO. After crystal violet dyeing, the biofilm formation of A. baumannii was promoted/inhibited by extremely low/relatively high concentration of LCEO, respectively. LCEO and chloramphenicol have synergistic growth inhibitory effect against A. baumannii according to the Fractional Inhibitory Concentration Index (FICI) value = 0.375. Our results indicate that the growth of A. baumannii was inhibited by LCEO, and give insights into the stress response of A. baumannii under sub-lethal concentrations of LCEO. These results provided evidence that A. baumannii was inhibited by LCEO, and expanded knowledges of stress response of A. baumannii under sub-lethal concentration of LCEO.

Effect of selenium-enriched probiotics on laying performance, egg quality, egg selenium content, and egg glutathione peroxidase activity.

A 35-day experiment was conducted to evaluate the effect of selenium-enriched probiotics (SP) on laying performance, egg quality, egg selenium (Se) content, and egg glutathione peroxidase (GPX) activity. Five hundred 58-week-old Rohman laying hens were randomly allotted to 5 dietary treatments of 100 each. Each treatment had 5 replicates, and each replicate had 5 cages with 4 hens per cage. The SP was supplemented to a corn-soybean-meal basal diet at 3 different levels that supplied total Se at 0.2, 0.5, and 1.0 mg/kg. The basal diet served as a blank control, while the basal diet with supplemental probiotics served as a probiotics control. The results showed that dietary SP supplementation not only increased (p < 0.05) the rate of egg laying, day egg weight, mean egg weight, egg Se content, and egg GPX activity but also decreased (p < 0.05) the feed:egg ratio and egg cholesterol content. The egg Se content was gradually increased (p < 0.05) along with the increasing level of dietary Se. The SP supplementation also slowed down (p < 0.05) the drop of Haugh units (HU) of eggs stored at room temperature. The egg GPX activity had a positive correlation (p < 0.01) with egg Se content and a negative correlation (p < 0.01) with egg HU drop. These results suggested that Se contents, GPX activity, and HU of eggs were affected by the dietary Se level, whereas the egg-laying performance and egg cholesterol content were affected by the dietary probiotics. It was concluded that this SP is an effective feed additive that combines the organic Se benefit for hen and human health with the probiotics benefit for laying hen production performance. It was also suggested that the eggs from hens fed this SP can serve as a nutraceutical food with high Se and low cholesterol contents for both healthy people and patients with hyperlipidemia, fatty liver, or cardiovascular disease.

Phylogenetic analysis of the E2 gene of classical swine fever virus from the Guangxi Province of southern China.

In this study, suspected classical swine fever (CSF) samples from the Guangxi Province of China were obtained from pigs with acute CSF, aborted fetuses, newborn pigs that died at 1-2 days of age, tonsils of healthy pigs, and leukocytes of immunized sows during 2001-2009. About 92 of 775 samples were found to be positive by RT-PCR, and 41 isolates were obtained. Phylogenetic analysis was performed on the 31 isolates by sequencing the E2 gene, and the isolates were found to cluster into two groups: (1) isolates from aborted fetuses (except GXGZ02), deceased newborn baby pigs, tonsils of healthy pigs, and leukocytes of immunized sows belonged to group 1.1, along with vaccine strain, HCLV, and standard virulent strain, Shimen, of China, and (2) 20 isolates from pigs with acute CSF belonged to group 2.1, 13 of which were clustered into subgroup 2.1b with isolates from other provinces of China, and 7 of which were clustered into subgroup 2.1a with isolates from Italy and Germany.

Regulation of expression and activity of selenoenzymes by different forms and concentrations of selenium in primary cultured chicken hepatocytes.

The expression and activity of selenoenzymes are regulated by Se. In the present study, the effects of different forms and concentrations of Se on the regulation of glutathione peroxidase (GPx) activity and phospholipid hydroperoxide GPx (GPx4) and type I deiodinase (D1) mRNA levels in chicken hepatocytes were evaluated. Primary cultured chicken hepatocyte monolayers derived from male White Leghorn chickens (aged 30-40 d) were incubated for 24 h with 0 (control), 0.5, 1, 1.5, 2, 3, 4 or 5 µmol/l of Se supplied as dl-selenomethionine (Se-Met), κ-selenocarrageenan (Se-Car) or sodium selenite (Na2SeO3). Compared with the control, Se significantly increased GPx activity in all the hepatocytes, but the activity was not increased in the hepatocytes treated with 5 µmol/l of Na2SeO3, with maximal effects being observed at 2 µmol/l of Se-Met or Se-Car and at 1.5 µmol/l of Na2SeO3, respectively. Significant decreases in GPx4 mRNA levels were observed in all the hepatocytes treated with Se (v. control). The D1 mRNA levels were significantly increased in all the groups treated with Se (v. control), with maximal effects being observed at 1.5 µmol/l of Se-Met and at 0.5 µmol/l of Se-Car or Na2SeO3, respectively. Se-Met at doses of 1.5-5 µmol/l had a greater effect on D1 mRNA than Se-Car and Na2SeO3 at equivalent doses. After resulting in a maximal effect, higher Se supplementation led to a dose-dependent reduction in GPx activity and D1 mRNA levels in all the hepatocytes treated with Se. These results suggest that in chicken hepatocytes, the regulations of GPx and D1 by different forms and concentrations of Se vary.

Effects of selenium form on blood and milk selenium concentrations, milk component and milk fatty acid composition in dairy cows.

BACKGROUND: Human health may be improved if milk with a favorable fatty acid composition and Se concentration is ingested. The present study is to determine how a basal diet supplemented with daily 5 mg Se as Se-enriched yeast (SY) or sodium selenite (SS) affects the fatty acid composition and Se concentration of bovine milk. The effects of Se form on blood Se concentration, erythrocyte glutathione peroxidase 1 (GPx1) activity, serum GPx3 activity and milk yield and component were also studied. RESULTS: Both Se forms, when compared to control group, increased Se concentrations of blood (P < 0.01) and milk (P < 0.01), erythrocyte GPx1 activity (P < 0.05) and milk percentages of polyunsaturated fatty acids (PUFA) (P < 0.05) and cis-9,cis-12 linoleic acid (P < 0.05). Cows supplemented with SY had higher Se levels in blood (P < 0.01) and milk (P < 0.01) and percentage of PUFA in milk (P < 0.05) when compared with those supplemented with SS. Milk yield, milk component and serum GPx3 activity were not significantly affected by Se form. CONCLUSION: Supplementation of diet with SY appears to be of more benefit than SS in producing favorable milk with high PUFA and Se concentrations.

Regulation of cellular glutathione peroxidase by different forms and concentrations of selenium in primary cultured bovine hepatocytes.

The expression and activity of cellular glutathione peroxidase (GPx1) are regulated by selenium (Se). Generally speaking, organic forms of Se have less toxicity and greater bioavailability compared with inorganic forms. In this study, the effects of different forms and concentrations of Se on the regulation of mRNA level and activity of GPx1 in bovine hepatocytes were evaluated, and the optimal doses of different forms of Se that supported the full expression of GPx1 were determined. Primary cultured bovine hepatocyte monolayers derived from neonatal male Holstein calves (aged 1-2 days) were incubated for 24 h with 0 (control), 0.5, 1, 1.5, 2, 3, 4 or 5 micromol/L of Se from dl-selenomethionine (Se-Met), sodium selenite (Na(2)SeO(3)) or Kappa-selenocarrageenan (Se-Car). Compared with controls, a significantly lower level of release of lactic dehydrogenase (LDH) was observed at 0.5-5 micromol/L of Se-Met, 0.5-1 micromol/L of Na(2)SeO(3) and 0.5 micromol/L of Se-Car, but significantly higher LDH release was observed at 2-5 micromol/L of Na(2)SeO(3) and 3-5 micromol/L of Se-Car, and the response occurred in a dose-dependent manner. The intracellular content of reduced glutathione in all hepatocytes treated with Se was significantly lower than that of controls. Significant increases in GPx1 mRNA were obtained in all hepatocytes treated with Se, with maximal effects at 3 micromol/L of Se-Met, 1.5 micromol/L of Na(2)SeO(3) and 2 micromol/L of Se-Car, respectively. Furthermore, 3 micromol/L of Se from Se-Met resulted in peak levels of GPx1 mRNA. After reaching a maximal level, higher Se supplementation led to a reduction of GPx1 mRNA. The activity of GPx1 showed similar patterns but of lower magnitude. We conclude that (a) the regulation of mRNA level and activity of GPx1 in primary cultured bovine hepatocytes by different forms of Se varies and (b) the optimal doses of Se to support the full expression of GPx1 in bovine hepatocytes when supplied as Se-Met, Na(2)SeO(3) and Se-Car are 3, 1.5 and 2 micromol/L, respectively.

Antibacterial action of selenium-enriched probiotics against pathogenic Escherichia coli.

The purpose of this study was to evaluate the inhibitory activity of selenium-enriched probiotics against pathogenic Escherichia coli (E. coli) in vitro and in vivo. Escherichia coli was co-cultured in vitro with each probiotic strain individually, and a mixture of the four strains and its population was counted at various time points. We also collected a cell-free culture supernatant (CFCS) of each probiotic strain and the four-strain mix to examine their antibacterial activity, using the cylinder plate method. Results demonstrated that co-culture with probiotics significantly reduced the number of E. coli. The different sizes of the inhibition zones made by each CFCS proved that E. coli was inhibited by the metabolites of the probiotics. In vivo, Kunming mice were allocated to different groups supplemented with selenium-enriched and other probiotics. After 28 days, the mice were inoculated with pathogenic E. coli so that we could compare mortality rates and inspect other indexes of each treatment. The mortality of the group with selenium-enriched probiotics was the lowest. In addition, the organic antioxidant status improved, immunity was fortified, and the internal environment of the intestinal tract was enhanced with selenium-enriched probiotic supplementation. In conclusion, selenium-enriched probiotics can strongly antagonize pathogenic E. coli in vitro and in vivo.