Production of heterozygous and homozygous clones in Nile tilapia

Production of heterozygous and homozygous clones of Nile tilapia (Oreochromis niloticus L.) was successfully carried out. An outbred clonal line was produced by cross-breeding between a viable mitotic gynogenetic female and male (recessive mutation in a sex determining gene). At the same time, an inbred clonal line was produced by gynogenetic reproduction (retention of 2nd polar body) using optimal pressure/heat shock treatments. The heterozygous and homozygous nature of the two types of clonal lines were checked and identified at the adenosine deaminase ADA* marker locus. A model for the large scale production of similar clones is presented. The possible implications of such clonal lines in genetic research and in the culture of Oreochromis spp. are discussed. © Rapid Science Ltd. 1998