Association Between of the Growth Hormone Gene GH-1 with Growth Indicators of Common Carp Cyprinus carpio L. in Three Different Ecosystems

Abstract

This study was conducted in the central of health laboratory/Animal and Fish Resource Research Center, Agricultural Research Department, Ministry of Science and Technology, for the period from 15/8/2021 to 15/11/2021 in order to investigate the polymorphism of the growth hormone gene GH-1 and its relationship to the productive performance (body weight, total length, age and case factor) of common carp Cyprinus carpio, in 90 fish representing three different ecosystems (30 fish for each site) including floating cages, ponds, and the environment of the Tigris River, south of Baghdad, with an average weight of (975-1517±150) g. Some physical and chemical measurements of water were measured, including temperature, dissolved oxygen concentration, pH, and salinity. These fish were transferred to the laboratory, and the weight, total length, and age of each fish were measured, as well as DNA extraction for the purpose of amplifying the size of a segment (459pb) of the growth hormone gene that includes exon 4, intron 4, and exon 5 by polymerase chain reaction PCR using primers designed for this gene. The genotypes of the growth hormone gene were investigated using the Single-Stranded Conformation Polymorphism (SSCP) technique, and the produced bands were compared to distinguish different genotypes of the gene by the electrophoresis method. The results showed that the water temperature was close to the environmental systems under study and ranged between (25.4-27 ± 0.50), the rates of dissolved oxygen concentration were (6.5 ± 0.09) mg/l, pH (7.0 ± 0.02) and salinity 0.8 g/l higher in ponds compared to the lowest value of them in the river. The analysis of the SSCP technique revealed the presence of six different genotypes of this hormone, including A, B, C, E, F, and H with a frequency of 24.4, 5.6, 15.6, 15.6, 16.4, and 22.4, respectively, for the fish community in the studied sites. The H genotype was significantly (P< 0.05) superior in the floating cages in the average body weight (1600 ± 0 g) and the relative case coefficient (2.5 ± 0). significant differences were observed in the average total body length and age, according to the multiplicity of genotypes. We conclude from this study an improvement in the growth and health status of common carp in cages and ponds compared to the river at the probability level (P<0.05) and the possibility of focusing on the polygenic genotypes of the growth hormone gene and adopting the H genotype as a guide for selecting fish mothers in genetic improvement programs for artificial propagation and achieving the largest economic return from fish breeding projects.