Evaluation of the productive performance characteristics of red tilapia (Oreochromis sp.) injected with shark DNA into skeletal muscles and maintained diets containing different levels of probiotic and amino yeast

This work aimed to study the effect of direct injection of shark (Squalus acanthias L.) DNA into skeletal muscles of red tilapia (Oreochromis sp.) fed at different additive levels (two probiotic levels; 0.3 and 0.5%, two amino yeast levels; 0.5 and 1.0% and a mixed of 0.3% probiotic and 0.5% amino yeast), on the productive performance. The results show that red tilapia injected with DNA had significant (P≤0.05) superiority of growth performance and feed utilization; besides the body composition was improved. In addition, the different levels of probiotic and amino yeast were more effective in stimulating most of the productive performance traits compared to the control group and the mixed of probiotic and amino yeast. The result indicates a possible easy and rapid way for improving red tilapia characteristics.Key words: red tilapia, shark DNA, direct injection, productive performance, probiotic, amino yeast

Heterozygote Advantage for Fecundity

Heterozygote advantage, or overdominance, remains a popular and persuasive explanation for the maintenance of genetic variation in natural populations in the face of selection. However, despite being first proposed more than 80 years ago, there remain few examples that fit the criteria for heterozygote advantage, all of which are associated with disease resistance and are maintained only in the presence of disease or other gene-by-environment interaction. Here we report five new examples of heterozygote advantage, based around polymorphisms in the BMP15 and GDF9 genes that affect female fecundity in domesticated sheep and are not reliant on disease for their maintenance. Five separate mutations in these members of the transforming growth factor β (TGFβ) superfamily give phenotypes with fitness differentials characteristic of heterozygous advantage. In each case, one copy of the mutant allele increases ovulation rate, and ultimately litter size per ewe lambing, relative to the wildtype. However, homozygous ewes inheriting mutant alleles from both parents have impaired oocyte development and maturation, which results in small undeveloped ovaries and infertility. Using data collected over many years on ovulation rates, litter size, and lambing rates, we have calculated the equilibrium solution for each of these polymorphisms using standard population genetic theory. The predicted equilibrium frequencies obtained for these mutant alleles range from 0.11 to 0.23, which are amongst the highest yet reported for a polymorphism maintained by heterozygote advantage. These are amongst the most frequent and compelling examples of heterozygote advantage yet described and the first documented examples of heterozygote advantage that are not reliant on a disease interaction for their maintenance