Induction of triploidy and erythrocyte cell size analysis of triploid African catfish, <i>Clarias gariepinus</i> (Burchell, 1822)

Abstract

In this study, genetic manipulation technique was employed to produce triploid African catfish Clarias  gariepinus. Artificial fertilization was carried out using synthetic hormone (Ovaprim®) at 0.5 ml/kg body  weight. Eggs numbering 100 ± 10 in quadruplicates from C. gariepinus were fertilized by milt from the  male species. The fertilized eggs were subsequently transferred to a thermoregulated refrigerator at 2^oC  for 20 minutes to suppress cell division 4 minutes after fertilization. Haploid larvae were produced by fertilizing the eggs with ultraviolet (UV) irradiated milt at 30000 μWcm^-2 for 15 minutes. Fertility, hatchability and survival after one week for triploids were 82.5%, 69.8% and 61.3%; for haploid, 100%, 15%, 0% and diploid  (controls), 100%, 93% and 91%, respectively. There was significant (p<0.05) variation among the ploidy  catfish larvae developed across the parameters of fertility, hatchability and survival determined. The ploidy levels of the triploid species were evaluated by karyotyping and erythrocyte measurements. The chromosome numbers obtained were 28 ± 2, 56 ± 2 and 84 ± 2 for haploid, diploid and triploid treatments, respectively. Erythrocyte cell size measurements of the triploid C. gariepinus species revealed bigger and larger cellular volume of about 1.5 times to that of the diploid.

Keywords: Genetic manipulation, Triploid, African catfish, Clarias gariepinus, Ultraviolet, Karyotyping, Erythrocyte, Chromosome