To evaluate the genetic variability among the modified
fish genomes and their control, two random primers were
used to determine DNA fingerprinting in muscle tissues
injected with various doses of shark DNA as well as
control sample. The polymorphic fragments varied
between 54.55% for primer 1 and 14.29% for primer 2
(Figure 2). These data showed high polymorphism
among normal and modified genomes. It may be due to
the differences in the DNA molecule among normal and
modified fish as a result of direct injection of different
concentrations of shark DNA. Moreover, some fragments
of shark DNA may randomly integrated into T. zillii
muscle genomes. This integration could be functional or
silent integration (Yaping et al., 2001). The same
observation were reported by El-Zaeem (2001), Ali (2002)
and Hemeida et al. (2004) following in vivo direct
injection of foreign DNA into target fish tissues. Also, the
sensitivity of the RAPD marker played an important role
in detection of these differences. Baradakci and Skibinski
(1994) and Neza et al. (2002) have suggested that the
RAPD analysis might be more sensitive than other
molecular techniques such mtDNA analysis which has
failed to reveal variations within tilapia populations.