Influence of dietary emamectin benzoate on the biological responses of monosex (all-male) Oreochromis niloticus (L.) fries.

The application of antiparasitic drugs plays a crucial role in the removal of infectious parasites in aquaculture. Emamectin benzoate (EB) is predominantly used as a feed premix against ectoparasites on temperate fish. This study evaluated the influence of 14 days of EB-dosing at 0-10 times the recommended dose (1X: 50 μg/kg biomass/day) on the biological responses and accrual/depletion of EB-residues in a tropical fish monosex Oreochromis niloticus fries.

Accumulation and clearance of tissue residues and health status of Nile tilapia Oreochromis niloticus (L.) juveniles as influenced by the extended oral oxytetracycline-dosing.

Antibiotics are considered an important primary therapy for bacterial diseases in aquaculture. This study evaluated the influence of oral administration of oxytetracycline (OTC) on feed intake, growth, mortality, residue accumulation and clearance, and histopathological changes in the vital organs of six groups of Nile tilapia Oreochromis niloticus when fed at 0-10 times the therapeutic dose (1×: 80 mg/kg biomass/day) for 10 and 20 consecutive days. The feed intake was reduced only slightly, viz.

Dietary therapeutic dose of oxytetracycline negatively influences the antioxidant capacity and immune-related genes expression in Nile tilapia Oreochromis niloticus (L.).

Effects of the dietary therapeutic dose of oxytetracycline (OTC) at 80 mg/kg biomass/day for consecutive 10 days on the behaviour, feed intake, mortality, residue accumulation and depletion, antioxidant capacity and immune-related genes expression in juvenile Nile tilapia Oreochromis niloticus were evaluated. OTC-dosing caused mortalities, reduced feed intake, and biomass reduction at 24.5-28.

Cloning and heterologous expression of ectoine biosynthesis genes from Bacillus halodurans in Escherichia coli.

The genes involved in the biosynthetic pathway of ectoine (2-methyl-1,4,5,6-tetrahydropyrimidine-4-carboxylic acid) from Bacillus halodurans were cloned as an operon and expressed in E. coli. Analysis of the deduced ectoine biosynthesis cluster amino acid sequence revealed that the ectoine operon contain 2,389 bp, encoded by three genes; ectA, ectB and ectC that encode proteins of 189, 427 and 129 amino acids with deduced molecular masses of 21,048, 47,120 and 14,797 Da respectively.