Prolactin i microsatellite as genetic markers for characterization of five oreochromis tilapia species and two oreochromis niloticus strains

Abstract

Hybrid tilapia is a major aquaculture food fish species in developing countries. The development of molecular markers to characterize and trace tilapia species is necessary to improve tilapia quality and enhance the competitive advantage of the aquaculture industry. Microsatellite markers have been suggested to assist breeding, species identification, and traceability system for tilapia. We used six microsatellites markers located within growth-related genes to discriminate between several tilapia species. We found that a combination of two microsatellites markers located within the proximal promoter of the prolactin I (PRL I) gene, PRL I-MS01 and PRL I-MS02, were able to discriminate between five Oreochromis tilapia species (O. mossambicus, O. aureus, O. niloticus, O. hornorum and O. spilurus) and two O. niloticus strains that exhibit the distinctive growth traits. Furthermore, we found that PRL I-MS01 microsatellite marker was able to trace parental origin of hybrid tilapia. Thus, this marker is a potentially beneficial tool for a tilapia traceability system. We conclude that the GT tandem repeats in PRL I-MS01 and CA tandem repeats in PRL I-MS02 are useful genetic markers to characterize diverse tilapia species, assist in the genetic tracing and conventional breeding of superior strains and strengthen the management of the tilapia aquaculture industry. There was strong relationship between the cold and both temperature at death and cumulative degree hours represented by negative correlation coefficient for all tested fish. There was no correlation between cold tolerance and fish size for all tested fish. The cooling degree hours were significantly different between the selected and non-selected O. niloticus (P<0.005). The selected O. aureus exhibited greater cold tolerance than the non-selected and death began at 14.1°C, while non-selected occurred at 15.2°C.