الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
Prolactin gene (PRL) is a candidate gene for egg production in poultry that located on the chromosome number 2; it is a polypeptide with molecular weight 21700-26000 Dalton. In birds, PRL affects a wide variety of physiological functions. It is crucial to the onset and maintenance of broodiness which is a behavioral trait observed in most common breeds of birds and considered as a major cause of poor egg production. An abundance of single nucleotide polymorphism (SNP) was reported in the 5′- flanking region, 3’ - flanking region, and the coding region of the signal peptide indicating its usefulness as a molecular marker for egg production. This study aim to screen the SNPs of five exons of chicken PRL gene in four commercial chicken lines reared in Egypt named Hubbard F15, Lohman, Cobb 500, and Avian 48 and analyze their correlation with egg production trait in order to identify further selection methods to increase the productive capacity of poultry. Genomic DNA of chicken breeds under the study was extracted using Thermo Scientific GeneJET Whole Blood Genomic DNA Purification. Five exons were amplified by PCR and sequenced by direct sequencing method. Sequence alignment of the resulted sequences to locate sequence variants in DNA and protein sequences were done by CLUSTAL W method using Laser gene Megalign program (Ver5.52, 2003, DNASTAR Inc). The results detected presence of Three SNPs in prolactin gene; one SNP in cPRL gene exon 2 (3838 bp) and two SNPs in cPRL gene exon 5 (7921 bp, 8187bp). SNP in exon 5 (7921 C/T) results in amino acid changes at positions 169 (P/S). The change in nucleotide and amino acid sequences did not affect egg production in chicken breeds under the study.