In a previous experiment in which Nile tilapia fry were successfully masculinized, we investigated how the concentration of trenbolone acetate (TA) in the immersion water changed before and after treatment. The results from that experiment indicated that the concentration of TA before and after treatment of Nile tilapia fry was highly variable and below the expected levels. Therefore, we decide...

Males and females of the same species differ largely in gene expression, which accounts for most of the morphological and physiological differences and sex-specific phenotypes. Here, we analyzed sex-specific gene expression in the brain and the gonads of cichlid fishes from Lake Tanganyika belonging to four different lineages, so-called tribes (Eretmodini, Ectodini, Haplochromini, and Lamprolog...

Microinjection is commonly performed to achieve fish transgenesis; however, due to difficulties associated with this technique, new strategies are being developed. Here we evaluate the potential of lentiviral particles to genetically modify Nile tilapia cells to achieve transgenesis using three different approaches: spermatogonial stem cell (SSC) genetic modification and transplantation (SC), i...

Hox gene clusters encode a family of transcription factors that govern anterior-posterior axis patterning during embryogenesis in all bilaterian animals. The time and place of Hox gene expression are largely determined by the relative position of each gene within its cluster. Furthermore, Hox genes were shown to have their expression fine-tuned by regulatory microRNAs (miRNAs). However, the mec...

Seventeen-day-old Nile tilapia fry were fed a standard diet (C) or diets containing 50-700 mg kg(-1) Quillaja saponin (QS) extract (groups S50, S150, S300, S500 and S700). After the first 8 weeks, 30 randomly selected tilapia from each of the treatments were placed in separate aquaria and fed the standard diet without saponins from then on (these were designated S50/C, S150/C, S300/C, S500/C an...

Metabolic mechanisms underlying the divergent response of rainbow trout (Oncorhynchus mykiss) and Nile tilapia (Oreochromis niloticus) to changes in dietary macronutrient composition were assessed. Fish were fed one of four isoenergetic diets having a digestible protein-to-digestible energy (DP:DE) ratio above or below the optimal DP:DE ratio for both species. At each DP:DE ratio, fat was subst...

Dietary supplements phosphatidylcholine and β-carotene, a dimer of vitamin A have been shown have positive effectson a variety of physiological and immunological parameters in humans and other vertebrates. Previous studies have demonstrated that these neutraceuticals enhance growth of Nile tilapia reared under optimal temperature. However, in those studies specially formulated diets were used. ...

About 14, 000 years ago, Lake Victoria contained 500 species. Of these original species, 200 have become extinct and 200 are on the endangered species list (DuHamel, 2004). Predation coupled with poor harvesting methods has caused a big economic loss on most Ugandan lakes in particular and the world at large. In this study, we formulate a model based on a standard Lotka-Volterra prey-predator m...

The chronic effect of environmental methomyl on the antioxidant system in testis Nile tilapia (Oreochromis niloticus) and its recovery pattern was investigated. Tilapia were exposed to sublethal concentrations 0.2, 2, 20 200 ?gL?1 for 30 days thereafter moved methomyl-free water 18 days. Antioxidant levels testis, including glutathione peroxidase, catalase, glutathione-S-transferase, reductase,...

A study was conducted to evaluate the pathogenicity and pathology of Achlya proliferoides BSN-M005 and Saprolegnia diclina BSN-M003, isolated from saprolegniosis outbreaks against immature stages of Nile tilapia, Oreochromis niloticus. The cumulative mortality rates of the tested fish groups that exposed to high zoospore concentrations of A. proliferoides BSN-M005 and S. diclina BSN-M003 were 6...