In vitro and in silico analyses reveal the interaction between LysM receptor-like kinase3 of Solanum tuberosum and the carbohydrate elicitor Riclin octaose.

As a carbohydrate elicitor, Riclin octaose (Rioc) activates the pattern-triggered immunity of Solanum tuberosum L., while how the plant perceives Rioc is unknown. Here, a pattern recognition receptor StLYK3 (LysM receptor-like kinase3) whose transcription level was significantly up-regulated after Rioc elicitation was investigated in vitro and in silico. The nucleotide that encoded the ectodomain of StLYK3 (StLYK3-ECD) was heterologously expressed in the Pichia pastoris strain GS115. The purified StLYK3-ECD had the molecular weight of 25.08 kDa and pI of 5.69. Afterwards interaction between StLYK3-ECD and Rioc was analyzed by isothermal titration calorimetry. The molar ratio of ligand to receptor, dissociation constant, and enthalpy were 1.28 ± 0.04, 26.7 ± 3.1 µM, and -45.0 ± 1.8 kJ mol-1 , respectively. Besides, molecular dynamics results indicated that StLYK3-ECD contained three carbohydrate-binding motifs and the first two motifs probably contributed to the interaction with Rioc via hydrogen bond and van de Waals' forces. Amino acids containing hydroxyl, amidic, and sulfhydryl groups took the main portion in the docking site. Moreover, replacing the 92nd threonyl (T) of StLYK3-ECD with valyl (V) resulted in the alteration of the preferred docking site. The dissociation constant drastically increased to 841.6 ± 232.4 µM. In conclusion, StLYK3 was a potential receptor of Rioc.

Chemical composition and larvicidal activity against Aedes mosquitoes of essential oils from Arisaema fargesii.

BACKGROUND: Dengue fever is caused by the spread of dengue virus by Aedes mosquito vectors. Currently, the most effective way to control dengue is by preventing mosquitoes from spreading the disease. Arisaema fargesii is a Chinese herbal medicine commonly used to repel mosquitoes. In our laboratory, anti-mosquito chemical components were extracted from A. fargesii, and the effects of these substances on mosquito larvae were examined. RESULTS: In total, 48 compounds corresponding to 98.79% of the total oil were identified and the major compounds identified were linalool (12.38%), carvacrol (8.27%), eugenol (5.21%), and ß-selinene (5.36%). Essential oil had larvicidal activity against Ae. aegypti and Ae. albopictus with LC50 values of 40.49 mg/L, 47.01 mg/L, respectively. The LC50 values of carvacrol, eugenol, linalool and ß-selinene were 32.78, 56.34, 70.56, 136.03 mg/L against Ae. aegypti larvae, and 39.08, 52.07, 82.34, 151.74 mg/L, respectively, against Ae. albopictus larvae. Biochemical assays of Aedes larvae showed that the activities of acetylcholinesterase (AChE), monooxygenases (MO), glutathione-S-transferase (GST), p-Nitrophenyl acetate (p-NPA) esterase, α-esterase and ß-esterase were significantly affected by carvacrol. Essential oil induced the detoxification mechanism for the action of GST and MO. CONCLUSION: The result indicates that essential oil of A. fargesii and its isolated constituent have good inhibitory effects on the defense enzymes of Aedes mosquito larvae. A. fargesii essential oil can be used to control Aedes mosquito larvae to prevent the spread of dengue fever. © 2019 Society of Chemical Industry.

Effects of dietary yeast hydrolysate on the growth, antioxidant response, immune response and disease resistance of largemouth bass (Micropterus salmoides).

A 56-day growth trial was conducted to investigate the effects of dietary yeast hydrolysate on the growth performance, antioxidation, immune response and resistance against Aeromonas hydrophila in largemouth bass. Four experimental diets were prepared with yeast hydrolysate levels of 0% (Y0), 1.5% (Y1.5), 3.0% (Y3.0) and 4.5% (Y4.5). Each diet was randomly assigned to triplicate 150-L tanks and each tank was stocked with 30 largemouth bass (initial body weight, IBW = 7.71 ±â€¯0.02 g). A challenge test was carried out after the feeding trial by injecting A. hydrophila intraperitoneally for 4-day observation. The results showed that the FBW and WGR in Y1.5 group were significantly higher than those in Y0 group (P < 0.05) and the feed conversion ratio (FCR) got the lowest value in Y1.5 group. And the hydrolysate supplement significantly increased the 4-day cumulative survival rate after the bacterial challenge (P < 0.05). The plasma malondialdehyde was lower in the yeast hydrolysate supplement groups in both pre- and post-challenge test (P < 0.05), while the plasma C3 increased (P < 0.05). In post-challenge test, the plasma superoxide dismutase (SOD) and catalase (CAT) activities increased in the Y1.5 and Y3.0 groups respectively (P < 0.05), and plasma lysozyme in Y1.5 group and the plasma IgM in Y3.0 group were higher than those in others respectively (P < 0.05). For the q-PCR results, in post-challenge test, the hepatic hep2 expression level in Y1.5 and Y4.5 groups were both significantly higher than those in others (P < 0.05), as well as il-8 in Y3.0 group. The spleen hif-1alpha and tgf-beta1 expression levels in Y4.5 group were all significantly lower than those in others (P < 0.05), while the gilt was significantly higher (P < 0.05) in the post-challenge test. And the expression levels of spleen tnf-alpah1 in Y1.5 and Y3.0 groups and il-8 in Y3.0 group were all significantly higher than those in other groups (P < 0.05) in the post-challenge test. The head kidney gilt expression level was significantly higher in the yeast hydrolysate supplement groups compared with the Y0 group (P < 0.05), and the head kidney il-8 expression level in Y1.5 group was significant higher than those in other groups in post-challenge test (P < 0.05). The present results indicated dietary yeast hydrolysate improved the antioxidant ability and enhanced the immune response of largemouth bass without negative effect on growth. And 1.5% or 3.0% of dietary yeast hydrolysate was recommended for largemouth bass based on the present results.

Effects of dietary supplementation with yeast glycoprotein on growth performance, intestinal mucosal morphology, immune response and colonic microbiota in weaned piglets.

Antibiotics are commonly provided to weaned piglets; however, this practice has become controversial due to the increased occurrences of microbial resistance, and alternatives are needed. This study aimed to investigate the effects of dietary supplementation with yeast glycoprotein (YG) on growth performance, intestinal mucosal morphology, immune response and colonic microbiota in weaned piglets. A total of 240 weaned piglets (d 23 ± 2) from 16 pens (15 piglets per pen) were randomly allocated to an antibiotics group (25% quinocetone 200 mg kg-1 and 4% enduracidin 800 mg kg-1 of the basal diet) or a YG group (800 mg kg-1 YG of the basal diet), respectively. The trial lasted 14 days, and at the end of the trial, one piglet per pen was chosen to collect plasma, intestinal tissue and colonic digesta samples. The results indicate that piglets fed diets containing YG tended to show increased final body weight (0.05 < P < 0.1), increased average daily gain (P < 0.05) and decreased F/G (P < 0.05) when compared with the antibiotics group. Moreover, intestinal permeability showed that YG led to an improvement in the intestinal development via decreasing serum content of DAO (P < 0.01). Histological evaluations showed that YG contributed to the improvement of the intestinal development via increasing villous height (P < 0.05) and the villous height to crypt depth ratio (P < 0.01), and decreasing crypt depth (P < 0.01) and villous width (P < 0.05) in the ileum. Intestinal integrity also showed that YG was conducive to improvement of the intestinal development via upregulating the m-RNA expression of occludin (P < 0.05) in the duodenal and jejunal mucosa. Interestingly, YG supplementation downregulated the m-RNA expression of IL-12 (P < 0.05), upregulated the m-RNA expression of Hsp-70 (P < 0.05) in the duodenal mucosa, downregulated the m-RNA expression of Hsp-70 (P < 0.05) and IFN-γ (P < 0.05), upregulated the m-RNA expression of Hsp-90 (P < 0.05) in the jejunal mucosa, and upregulated the m-RNA expression of Hsp-70 (P < 0.05) in the ileal mucosa. On the other hand, colonic microbiota results showed that YG supplementation increased the relative abundance of Lactobacillus (P < 0.05) in the genus level. Colonic metabolite results showed that YG supplementation decreased the content of acetate (P < 0.05). Taken together, it is speculated that YG would be a potent alternative to prophylactic antibiotics in improving the gut health in weaned piglets.

Chemical composition and antimicrobial activities of essential oil from Wedelia urticifolia growing wild in Hunan Province, China.

The essential oil obtained from Wedelia urticifolia growing in Hunan Province, China, was analyzed for the first time by capillary GC and GC-MS. A total of 67 constituents, representing 98.68% in essential oil were identified. The major constituents of the oil were: α-pinene (8.85%), limonene (6.38%), carvacrol (6.15%), caryophyllene (6.08%), spathulenol (5.49%), sabinene (5.36%), camphor (4.34%). Antimicrobial potential of oil against bacterial strains (Pseudomonas aeruginosa, Escherichia coli and Bacillus subtilis, and Staphylococcus aureus), yeast strains (Hansenula anomala and Saccharomy cescerevisiae) and molds (Aspergillus niger, Chaetomium globosum, Mucor racemosus, and Monascus anka) was determined by disc diffusion method and broth micro dilution method, respectively. The oil exhibited promising antimicrobial effect as a diameter of zones of inhibition (16.8-24.9 mm). Minimum inhibitory concentration values of oil were ranged 62.5-1000 µg/mL.