failure of pcr-rapd technique to differentiate sex in mahisefied (rutilus frisii kutum) from the south caspian sea

in order to identify the sex marker in mahisefied, rutilus frisii kutum, samples from 5 male and 5 female fish were collected from the south caspian sea. polymerase chain reaction random amplified polymorphic dna (pcr-rapd) was performed using 124 primer sets. all bands were numbered using 1 and 0 scores corresponding to the presence or absence of bands, respectively and data were analyzed using rapdplot program. results indicated that 44 sets of primers did not show any flanking site and produced no bands, while the remaining 80 produced sharp and visible bands on polyacrylamid gel. in total, 1600 bands were scored. however, none of the bands corresponded to either the male or female fish. according to the results it has been concluded that rapd technique failed to detect sex and cannot be considered as a robust molecular tool for sex differentiation in the studied fish. the reason may be the absence of sex chromosomes in this species or that the genes corresponding to sex differentiation are spread on different autosomal chromosomes with interaction of some environmental factors.