الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Four fish species; two fresh water fish (Oreochromis niloticus L. and Tialpia zillii L.), and two marine fish (Liza ramada L. and Mugil cephalus L.) were used in this study. These species were collected from Damietta and Port Said governorate, respectively. The aims of this study were to: a) Study the genetic variation within and between freshwater and marine water fish using both fingerprinting (e.g. fluorescence AFLP) and partial sequencing of growth hormone gene for each species. b) Isolate and sequence intron 5 of growth hormone (GH) gene to study inter specific variation among freshwater and marine fish. c) Test the genetic variation for being associated to the species habitats.1. Amplified Fragment Length Polymorphism (AFLP) fingerprint DNA was isolated from caudal fin tissue from 12 samples which represented 4 species; two freshwater fish (Oreochromis niloticus L. and Tialpia zillii L.), and two marine fish (Liza ramada L. and Mugil cephalus L.). Three samples of each species were used. DNA was digested by using EcoR1 and Mse1 restriction enzymes with three selective primers and adaptors. PCR amplification was successful for three pairs of primers which represented four species under study. The rate of amplification was 111, 147 and 124 bands for three primer pairs, respectively. Peak analysis and automated band scoring were successful and quality tests showed adequate quality. Band scoring for each primer pair were between 50 bp – 700bp. Percentage of polymorphic loci was 25.13% in Bouri, 51.31% in Toubar, 45.55% in Green-belly tilapia and 45.03% in Nile tilapia. A total of 382 polymorphic bands were scored from three primer pairs for all 12 samples which represented 4 species. 2. Growth hormone (intron5) gene Sequencing Four samples each represent a single species were used for DNA PCR amplification, purification and sequencing of intron 5 of GH gene. When successful, sequences were aligned with a reference sequence to detect the overall variation ratio (variation test) by dividing the total number of variations in nucleotide sequence by the total length of the sites. Successful reasonably variable candidate regions were used for sequencing all samples. One sample from each species was chosen to be sequenced which PCR products resulting from DNA extraction from each species under study. Sequence data generated 116 nucleotides which represent intron 5 of GH gene from all species under study. The current AFLP analysis was successfully able to determine that the phylogenetic analysis perfectly reflected the species type and the habitats type, that Nile tilapia and Green-belly set in the same sub-cluster which belonged to fresh water fish while Toubar and Bouri set in the sub-cluster which belonged to marine fish.In contrast to the PCoA that showed the habitat in accordance with the majority of life time in fresh water that Toubar spend more time during its life cycle in the fresh water than the Bouri. Structure analysis showed that the Toubar was more closely to the two fresh water species. Difference between among and within species according to AMOVA analysis refers to using samples with wide environmental range. Our current study for sequence of intron 5 of growth hormone (GH) gene showed differences between L. ramada, M. cephalus, O. niloticus & T. zillii which were successfully able to determine mutations, genetic studies and Deletion & Insertion nucleotides in intron 5 of GH gene between L. ramada, M. cephalus, O. niloticus & T. zillii. Polymophic single nucleotide and the numbers of A, C, G and T nucleotides for each fragment of intron 5 of GH gene also were determined.