The Effects of Oral Rehmannia glutinosa Polysaccharide Administration on Immune Responses, Antioxidant Activity and Resistance Against Aeromonas hydrophila in the Common Carp, Cyprinus carpio L.

The effects of the oral administration of Rehmannia glutinosa polysaccharide (RGP-1) on the immunoregulatory properties, antioxidant activity, and resistance against Aeromonas hydrophila in Cyprinus carpio L. were investigated. The purified RGP-1 (250, 500, and 1,000 µg/mL) was co-cultured with the head kidney cells of the common carp. The proliferation and phagocytosis activities of the head kidney cells, and the concentration of nitric oxide (NO) and cytokines in the culture medium were determined. Next, 300 common carps (47.66 ± 0.43 g) were randomly divided into five groups; the two control groups (negative and positive) were administered sterile PBS and the three treatment groups were administered different concentrations of RGP-1 (250, 500, and 1,000 µg/mL) for seven days. Subsequently, the positive and treatment groups were infected with A. hydrophila, and the negative group was administered sterile PBS for 24 h. The concentration of NO, cytokines, lysozyme (LZM), and alkaline phosphatase (AKP) in serum, the total antioxidant capacity (T-AOC), the levels of malonaldehyde (MDA) and glutathione (GSH), and the total activities of superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in the hepatopancreas of the common carp were tested. We observed that RGP-1 could significantly enhance the proliferation and phagocytosis activities (P < 0.05), besides inducing the production of NO, pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6, IL-12) and anti-inflammatory cytokines (IL-10, TGF-ß) (P < 0.05) in vitro. The in vivo experimental results revealed that RGP-1 significantly enhanced NO production, protein levels of pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6, IL-12), LZM and AKP activities, and the antioxidant content (T-AOC, SOD, CAT, GSH, GSH-Px, and MDA) compared to that observed in the negative group prior to A. hydrophila infection (P < 0.05). NO, pro-inflammatory cytokines, LZM and AKP activities were significantly lower than that in the positive group after infection (P < 0.05). However, whether infected or not, the expression of anti-inflammatory cytokines (IL-10, TGF-ß) increased significantly in the RGP-1-treated groups (P < 0.05). Therefore, the results suggested that RGP-1 could enhance the non-specific immunity, antioxidant activity and anti-A. hydrophila activity of the common carp, and could be used as a safe and effective feed additive in aquaculture.

Nocardia yunnanensis sp. nov., an actinomycete isolated from a soil sample.

A novel actinomycete strain, designated CFH S0054T, was isolated from a soil sample collected from Xiaokongshan in Tengchong, Yunnan Province, in south-west PR China. Phylogenetic analysis based on its 16S rRNA gene sequence indicated that strain CFH S0054T belonged to the genus Nocardia. Based on the results of 16S rRNA gene sequence analysis, strain CFH S0054T was most closely related to Nocardia concava IFM 0354T (98.3 %), Nocardia inohanensis NBRC 100128T (97.9 %), Nocardia otitidiscaviarum NBRC 14405T (97.9 %) and Nocardia heshunensis CFH S0067T (97.8 %). Strain CFH S0054T contained C16 : 0, C18 : 1 ω9c, C18 : 0 10-methyl (TBSA) and summed feature 3 as major cellular fatty acids and MK-8 (H4ω-cycl) as the major respiratory quinone. The polar lipid profile included phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and unknown phospholipids. The cell wall contained meso-diaminopimelic acid, and the whole-cell hydrolysates were arabinose, galactose, glucose, fructose, ribose and mannose. The genome of strain CFH S0054T was 7.9 Mbp with a G+C content of 68.4 mol%, the average nucleotide identity (ANI) values between strain CFH S0054T and N. concava IFM0354T were low (ANIm<87.7 % and ANIb=84.1 %). On the basis of phylogenetic, physiological and chemotaxonomic data, strain CFHS0054T is considered to represent a novel species of the genus Nocardia, for which the name Nocardiayunnanensis sp. nov. is proposed, The type strain is CFH S0054T (DSM 46763T=JCM 30082T).