Evaluation of the Multimycotoxin-Degrading Efficiency of Rhodococcus erythropolis NI1 Strain with the Three-Step Zebrafish Microinjection Method

Evaluating the In Vivo Virulence of Environmental Pseudomonas aeruginosa Using Microinjection Model of Zebrafish (Danio rerio)

(1) Background: Microinjection of zebrafish (Danio rerio) embryos offers a promising model for studying the virulence and potential environmental risks associated with Pseudomonas aeruginosa. (2) Methods: This work aimed to develop a P. aeruginosa infection model using two parallel exposition pathways on zebrafish larvae with microinjection into the yolk and the perivitelline space to simultaneously detect the invasive and cytotoxic features of the examined strains. The microinjection infection model was validated with 15 environmental and clinical strains of P. aeruginosa of various origins, antibiotic resistance profiles, genotypes and phenotypes: both exposition pathways were optimized with a series of bacterial dilutions, different drop sizes (injection volumes) and incubation periods. Besides mortality, sublethal symptoms of the treated embryos were detected and analyzed. (3) Results: According to the statistical evaluation of our results, the optimal parameters (dilution, drop size and incubation period) were determined. (4) Conclusions: The tested zebrafish embryo microinjection infection model is now ready for use to determine the in vivo virulence and ecological risk of environmental P. aeruginosa.

Aaqueous exposure to silver nanoparticles synthesized by abalone viscera hydrolysates promotes the growth, immunity and gut health of zebrafish (Danio rerio)

Silver nanoparticles (AgNPs) have the potential to be used in aquaculture, but their influence on the growth and health of aquatic organisms has not been extensively investigated. In this study, the abalone viscera hydrolysates decorated AgNPs (AVH-AgNPs) were dispersed into aquaculture water at different concentrations (0, 6, 9, and 18 μg/l) to evaluate the biological effects on zebrafish (Danio rerio). The results showed that the AVH-AgNPs treatments of 6 and 9 μg/l promoted the growth and did not cause obvious damage to the gills, intestines, and livers of zebrafish. All the treatments induced catalase (CAT) and superoxide dismutase (SOD) activities and increased glutathione (GSH) content in the livers and upregulated the expression of immune related genes. The effects of 9 and 18 μg/l AVH-AgNPs treatments were more obvious. After AVH-AgNPs treatment, the abundances of some potential pathogens, such as species Plesimonas shigelloides and Pseudomonas alcaligenes and genus Flavobacterium decreased significantly. In contrast, the abundance of some beneficial bacteria that can degrade pollutants and toxins (e.g., Rhodococcus erythropolis) increased significantly. Thus, the application of low concentrations (6 ~ 18 μg/l) of AVH-AgNPs in aquaculture water is relatively safe and has a positive effect on zebrafish farming.

Comparison Evaluation of the Biological Effects of Sterigmatocystin and Aflatoxin B1 Utilizing SOS-Chromotest and a Novel Zebrafish (Danio rerio) Embryo Microinjection Method

Aflatoxin B1 (AFB1) is a potent mycotoxin and natural carcinogen. The primary producers of AFB1 are Aspergillus flavus and A. parasiticus. Sterigmatocystin (STC), another mycotoxin, shares its biosynthetic pathway with aflatoxins. While there are abundant data on the biological effects of AFB1, STC is not well characterised. According to published data, AFB1 is more harmful to biological systems than STC. It has been suggested that STC is about one-tenth as potent a mutagen as AFB1 as measured by the Ames test. In this research, the biological effects of S9 rat liver homogenate-activated and non-activated STC and AFB1 were compared using two different biomonitoring systems, SOS-Chromotest and a recently developed microinjection zebrafish embryo method. When comparing the treatments, activated STC caused the highest mortality and number of DNA strand breaks across all injected volumes. Based on the E. coli SOS-Chromotest, the two toxins exerted the same genotoxicities. Moreover, according to the newly developed zebrafish microinjection method, STC appeared more toxic than AFB1. The scarce information correlating AFB1 and STC toxicity suggests that AFB1 is a more potent genotoxin than STC. Our findings contradict this assumption and illustrate the need for more complex biomonitoring systems for mycotoxin risk assessment.

Resveratrol Improves Intestinal Morphology and Anti-Oxidation Ability in Deoxynivalenol-Challenged Piglets

Simple Summary

Deoxynivalenol (DON)-contaminated feed may cause anorexia, vomiting, immunosuppression, and intestinal dysfunction in pigs, which would lead to growth retardation and great losses in the pig industry. In this study, the effects of resveratrol (RES) on growth performance, the intestinal barrier, antioxidant capacity, and mitochondrial function in weaned pigs fed with DON-contaminated diets were investigated. Dietary supplementation with resveratrol increased the average daily feed intake of piglets. Diets supplemented with resveratrol increased the villus height and the ratio of the jejunum villus height to crypt depth, increased the activities of superoxide dismutase (SOD), and increased the total antioxidant capacity in the jejunum mucosa. After being supplemented with RES, the level of reactive oxygen species (ROS) in mitochondria was decreased, while the mitochondrial membrane potential in the jejunum was increased. In conclusion, these results suggested that resveratrol effectively relieved DON-induced oxidative stress in weaned piglets, improved intestinal barrier function, enhanced mitochondrial function, and improved the growth performance of piglets.

Abstract

This study aimed to investigate the potential effects of resveratrol (RES) on intestinal function and oxidative stress in deoxynivalenol (DON)-challenged piglets. Twenty-four healthy Duroc × Yorkshire × Landrace weaned piglets at the age of 28 ± 1 days were randomly divided into four groups with six repetitions per group. The four groups were as follows: the control group (CON), fed with a basic diet; the RES group, fed with a basal diet + 300 mg/kg RES; the DON group, fed with a basal diet containing 2.65 mg/kg DON; and the DON + RES group, fed with a basal diet containing 2.65 mg/kg DON + 300 mg/kg RES. The results showed that the growth performance and intestinal function of DON-challenged piglets were significantly decreased (p < 0.05). Compared with the DON group, the average daily feed intake of piglets in the DON + RES group was significantly increased (p < 0.05). Additionally, dietary RES ameliorated DON-induced intestinal morphology impairment, as indicated by the increased (p < 0.05) jejunal villi height and the ratio of the jejunal villi height/crypt depth. Furthermore, after the addition of RES, the activities of superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) in the jejunum mucosa were significantly increased, and the content of malondialdehyde (MDA) was significantly declined (p < 0.05). In addition, the level of reactive oxygen species (ROS) in the mitochondria was significantly reduced by RES, while the mitochondrial membrane potential in jejunum was significantly increased by RES (p < 0.05). However, there was no obvious difference between DON + RES and DON groups on average daily gain and the ratio of feed togain, except for the significant inhibition of average daily feed intake (p < 0.05). In conclusion, RES could effectively alleviate the DON-induced oxidative stress on weaned piglets, and reduce the damage to mitochondria and intestinal morphology, so as to improve the growth performance of piglets.

Variations of enzymatic activity and gene expression in zebrafish (Danio rerio) embryos co-exposed to zearalenone and fumonisin B1

The natural co-occurrence of multiple mycotoxins has been reported in cereals and cereal products worldwide. Even though the dietary exposure to mycotoxins constitutes a serious human health, most reports are limited to the toxic effect of individual mycotoxins. The purpose of the present study was to assess the combined toxic effects of zearalenone (ZEN) and fumonisin B1 (FB1) and the potential interaction of their mixture on zebrafish (Danio rerio) embryos. Our results showed that ZEN possessed the higher toxicity to embryonic zebrafish (7-day LC₅₀ value of 0.78 mg a.i. L^-1) compared with FB1 (7-day LC₅₀ value of 227.7 mg a.i. L^-1). The combination of ZEN and FB1 exerted an additive effect on zebrafish embryos. Meanwhile, the activities of antioxidant CAT, caspase-3, and detoxification enzyme CYP450, as well as the expressions of six genes (Mn-sod, cas9, bax, cc-chem, ERα, and crh) associated with oxidative stress, cellular apoptosis, immune system, and endocrine system were prominently altered in the mixture exposure compared with the corresponding single treatment group of ZEN or FB1. Taken together, the regulatory standards of mycotoxins in food and feed should be updated based on the mixture effects of mycotoxins, and there is an increased need on effective detoxification methods for controlling and reducing the toxicity of multiple mycotoxins in animal feed and throughout the food supply chain.