Phenol oxidase (EC 1.14.18.1). A marker enzyme for defense cells

Effects of dietary glyceryl monolaurate supplementation on growth performance, non-specific immunity, antioxidant status and intestinal microflora of Chinese mitten crabs

This study aims to investigate the effects of glycerol monolaurate (GML) on growth performance, non-specific immunity, antioxidant capacity and intestinal microflora in Chinese mitten crabs. The crabs were randomly arranged to three experimental diets groups containing 0 (control group), 1000 mg/kg GML (GML1000 group), and 2000 mg/kg GML (GML2000 group), respectively. After 8 weeks of breeding, results showed a better growth performance in GML2000 group, with a higher PWG, SGR and lower FCR (P < 0.05). Meanwhile, in GML2000 group the activities of phenoloxidase, alkaline phosphatase, acid phosphatase and lysozyme in hemolymph were increased (P < 0.05), also the activities of hemolymph and hepatopancreas superoxide dismutase (SOD) and glutathione peroxidase (GPx) were increased in hepatopancreas (P < 0.05). While malondialdehyde (MDA) concentrations were lower significantly (P < 0.05) both in GML1000 and GML2000 groups. Furthermore, the mRNA expression of TLR1, TLR2, which related to the Toll pathway were increased (P < 0.05). Supplementation of 2000 mg/kg GML up-regulated the expression of ALF and LZM (P < 0.05), and down-regulated the expression of caspase-3 (P < 0.05). The abundance of Firmicutes increased in GML2000 group (P < 0.05), and Shewanella was significantly increased (P < 0.05) in both GML1000 and GML2000 groups. In conclusion, dietary supplemented with GML enhanced the growth performance and antioxidant capacity, enhanced hemolymph immune enzymes activities and antimicrobial peptides expression through regulating the proPO system and Toll pathway, and improved gut microflora in Chinese mitten crabs.

N-Acetyl-tryptophan glucoside (NATG) protects J774A.1 murine macrophages against gamma radiation-induced cell death by modulating oxidative stress

Immune system is amongst the most radiosensitive system to radiation-induced cellular and molecular damage. Present study was focused on the evaluation of radioprotective efficacy of a novel secondary metabolite, N-acetyl tryptophan glucoside (NATG), isolated from a radioresistant bacterium Bacillus sp. INM-1 using murine macrophage J774A.1 cells experimental model. Radioprotective efficacy of NATG against radiation-induced DNA damage and apoptosis was estimated using phosphatidyl-serine-externalization Annexin V-PI and Comet assay analysis. Radiation-induced cell death is the outcome of oxidative stress caused by free radicals. Therefore, perturbations in antioxidant enzymes i.e., superoxide dismutase (SOD), catalase, glutathione-s-transferase (GST) and GSH activities in irradiated and NATG pre-treated irradiated J774A.1 cells were studied. Results of the present study demonstrated that NATG pre-treated (0.25 µg/ml) irradiated (20 Gy) cells showed significant (p < 0.05) reduction in apoptotic cells index at 4-48 h as compared to radiation alone cells. Comet assay exhibited significant protection to radiation-induced DNA damage in J774A.1 cells. Significantly shortened DNA tail length, increased % Head DNA contents and lower olive tail moment was observed in NATG pre-treated irradiated cells as compared to radiation alone cells. Further, significant increase in catalase (~ 3.9 fold), SOD (67.52%), GST (~ 1.9 fold), and GSH (~ 2.5 fold) levels was observed in irradiated cells pre-treated with NATG as compared to radiation-alone cells. In conclusion, current study suggested that NATG pre-treatment to irradiated cells enhanced antioxidant enzymes in cellular milieu that may contribute to reduce oxidative stress and decrease DNA damage which resulted to significant reduction in the cell death of irradiated macrophages.

Plant products as antimicrobial agents

The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Ethnopharmacologists, botanists, microbiologists, and natural-products chemists are combing the Earth for phytochemicals and "leads" which could be developed for treatment of infectious diseases. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; Western medicine is trying to duplicate their successes. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. This review attempts to summarize the current status of botanical screening efforts, as well as in vivo studies of their effectiveness and toxicity. The structure and antimicrobial properties of phytochemicals are also addressed. Since many of these compounds are currently available as unregulated botanical preparations and their use by the public is increasing rapidly, clinicians need to consider the consequences of patients self-medicating with these preparations.

Pitfalls in the light microscopical detection of NADH oxidase

NADH oxidase activity has been detected at the ultrastructural level using cerium ions to trap H2O2 generated by the enzyme (via intermediate reactive oxygen species). In an attempt to localize NADH oxidase activity at the light microscope level using the cerium-diaminobenzidine (DAB)-nickel-H2O2, the cerium-DAB-cobalt-H2O2 or the cerium-alkaline lead procedures, the distribution patterns of the revealed enzyme were found to be identical to those for non-specific alkaline phosphatase and especially 5'-nucleotidase activity. With the cerium-DAB-cobalt-H2O2 visualization procedure, the distribution pattern of the final reaction product was similar to that obtained with the other two techniques but much less final reaction product was formed. Incubations for NADH oxidase activity performed in the presence of exogenous catalase or in the absence of catalase or peroxidase inhibitors did not affect the staining intensity, whereas inhibitors of 5'-nucleotidase (EDTA) and non-specific alkaline phosphatase (levamisole) always did. Therefore, phosphatases contribute to the formation of the final reaction product. Since NADH initially cannot be hydrolysed by either of these two phosphatases, then presumably nucleotide pyrophosphatase (E.C.3.6.1.9) cleaves NADH into 5'-AMP and nicotinamide mononucleotide in a first step. Both nucleotides can be hydrolysed further by the two monophosphatases. These then generate cerium phosphate which is detected by the DAB-nickel-H2O2, DAB-cobalt-H2O2 or lead visualization methods.