Evaluation of Genotoxicity in fish
RAPD-PCR: It is documented that wastewater often
contains genotoxic substances that can resist different
stages of the treatment process. RAPD-PCR and DNA
fingerprinting was performed on Catfish and Nile tilapia
fish genome to evaluate the genomic toxicity occurred to
fishes obtained from polluted areas compared with those
obtained from control one. 20 primers (10-mer random
primers) were used in our study. And from all used
primers only six primers were reacted and resulted in
positive and detectable bands (Fig. 2-5). Statistically, the
number of bands detected within the same group of fish
was not significantly different (p > 0.05), but were
significant in the numbers of bands observed between
polluted fishes and control fishes. Results showed
appearance of new bands in polluted fishes which are not
present in the control. Interestingly, our results are in
agreement with Zhang et al. [39]. RAPD profiles obtained
from our study showed that the treated wastewater (TWW) has genotoxic effects on fish. The different band
profile (appearance/disappearance) between polluted
fishes and control fishes was shown. A total of 257 bands
with an average of 5.3 bands per primer were detected.
Our results are similar to that obtained by Yoon and Kim
[40]. They used oligodecamers (20 - mer random primers)
to study genetic similarity and diversity between two
populations of Korean catfish (Silurus asotus) and the
average of bands obtained were 8.2–13.6 band per primer.
Additionally, the length of all the bands obtained in our
study was found in the range of 100–3000 bp (Figure 2 to
5) and, this band length was detected in the previous
work [40]. Rocco et al. [41] analyzed the genotoxic effects
of zebra fish DNA integrity after exposure to
pharmacological agents present in aquatic environments
based on RAPD method and they found that the bands
generated by the six primers were between 450 bp and
2000 bp in length and also Zhiyi and Haowen [42]
analyzed the genotoxic effects of cyclophosphamide
Danio rerio (zebra fish) with RAPD method and found that
the bands generated by the six primers were between from
300 to 2000 bp in length.