Lactobacillus plantarum enhances immunity of Nile tilapia Oreochromis niloticus challenged with Edwardsiella tarda
Authors: Sherif, Ahmed H.; Gouda, Mofeed Y.; Al-Sokary, Eman T.; Elseify, Mohamed M.
Edwardsiella tarda is a bacterial fish pathogen associated with high mortality in aquaculture. Lactobacillus plantarum, which is a probiotic with immunomodulatory properties, was used to improve the disease resistant in Nile tilapia (Oreochromis niloticus). One hundred twenty O. niloticus (60 +/- 5 g live body weight) were divided into four groups; the first (control) was fed on an unsupplemented diet, the second and the third group were fed on a diet supplemented with L. plantarum (10(12) bacterial cells/kg feed) for two weeks (G1) and four weeks (G2), and the fourth group (G3) was fed on a diet supplemented with antibiotic florfenicol for ten days. Haemogram, liver enzymes (AST, ALT and ALP levels), hepatic antioxidant enzymes (GPx and CAT) and serum creatinine were measured to assess the impacts of the additives on the health status of fish. The level of gene expressions of interleukin beta 1 (IL-1 beta), tumour necrosis factor (TNF)-alpha and IL-10 was measured after supplementation and challenge tests. Fish were challenged with the obtained median lethal dose (LD50) of E. tarda (2.54 x 10(6) CFU/ml). O. niloticus fed on supplemented diets with L. plantarum G1 and G2 showed significantly enhanced immune status even after fourteen days of the experimental infection with E. tarda; however, florfenicol treatment G3 (mortality 20%) had exhibited lower MR% compared with L. plantarum groups (mortality 43.3% for both) and the control (mortality 60%). L. plantarum could protect O. niloticus against E. tarda infection compared to the control with a significant enhancement of fish health that helps in the restoration of normal physiological status.
Growth and cardiovascular development are repressed by florfenicol exposure in early chicken embryos
Authors: Hu, Dongfang; Meng, Fanliang; Cui, Yunli; Yin, Mei; Ning, Hongmei; Yin, Zhihong; Chen, Lingli; Ge, Yaming; Liu, Sidang
Florfenicol (FLO) is one of the most popular antibacterial drugs used in veterinary clinics and aquaculture. The drug was found to decrease the hatchability of eggs laid by treated hens in veterinary clinics and research work. However, the pathological changes in developing embryos and their cardiovascular system and the mechanism underlying FLO-induced embryonic death remain unclear. In the present study, fertilized eggs laid by hens treated with a therapeutic dose of FLO were collected and incubated. Results showed that FLO exposure repressed embryonic development and induced early embryonic death. As a result, FLO decreased the hatchability and increased the proportion of weak chicks. Moreover, FLO exposure led to embryonic lethality and inhibited the development of chick embryos as characterized by decreased weights, lagging distribution of Hamburger-Hamilton stages, and dysplastic eyes. Pathological examination indicated that FLO exposure affected the normal development of the heart in 4.5-day-old chick embryos, as characterized by shorter transverse cardiac diameter, disordered arrangement of trabecular muscles in ventricles, and reduced thickness of ventricular walls. Furthermore, FLO decreased blood vascular densities and downregulated the expression levels of key angiogenesisrelated genes, including the vascular endothelial growth factor and fibroblast growth factor, in the yolk sac membrane. These findings indicated that FLO exposure restricted vascular development during early embryonic development. In summary, our data suggest that the restricted growth and abnormal cardiovascular development may be responsible for FLO-induced early embryonic death. Thus, these findings can be useful for guiding the proper use of FLO and in laying a foundation for further studies on the mechanism of FLO-induced embryonic toxicity.