الفهرس 
REVIEW ?F LITERATUREOnly 14 pages are availabe for public view
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Abstract
Cichlidae is one amongst the most prominent vertebrate families, new species are identified annually, and many species stay undescribed. Increasing the scientific interest about Cichlids due to the rapid adaptive radiation, that led to a significant ecological diversity and their vast importance to aquaculture. Tilapia is the current common name of the three genera and fish species of the Cichlidae family: Oreochromis, Tilapia and Sarotherodon. Tilapia are native to Africa are distributed throughout the globe. This study planned to detect and validate mitochondrial tRNA genes evolution mechanisms based on genetic variations in Egyptian tilapiine (O. niloticus, T. zillii, and S. galilaeus). Additionally, study their impact on secondary structure form, using the comparative mitogenomic approach. To development mitochondrial molecular marker based on tRNA genes for Egyptian tilapiine identification or population studies.
This study started with preliminary bioinformatics analysis to identify the candidate tRNA genes as a potential molecular marker. The main steps in bioinformatics analysis were: first, the tRNA genes were surveyed for cichlids species that exist in the database with a focus on the haplotilapiine species. Second, the secondary structure for all tRNA genes were predicted. Third, the variations in each tRNA gene were detected and their location in the tRNA structure. These steps followed by testing and validating those candidates using proper molecular genetic techniques (DNA extraction, PCR amplification, amplicon purification, sequencing, and bioinformatic analysis) in Egyptian tilapiine species.
The results indicated that trnD was the most variable tRNA gene in cichlids and haplotilapiine species, the same result recorded in Egyptian tilapiine species. The secondary structures of mt tRNA genes in the Cichlidae family were predicted and detected the most conservative structure, which was the anticodon loop. The highly mutant structure was D loop. Results presented here will be useful as genetic markers for species identification, and/or population studies. We suggest that Asp and Ile regions can be useful as a genetic marker for both species identifications and population studies. While His region can be used only in population studies. As for separated genes, trnD is a suitable interspecific marker, while the trnH, trnSGCU, trnQ are suitable intraspecific markers for S. galilaeus population. Finally, the trnI gene is a suitable interspecific marker and intraspecific marker for the O. niloticus population.