Production of homozygous diploid zebra fish ( Brachydanio rerio)

Abstract

The effectiveness of different shock treatments applied to inhibit the first mitotic division was investigated in two populations (gold- and wild-coloured) of zebra fish ( Brachydanio rerio) with regard to the production of homozygous gynogenetic fish. For inactivation of the paternal genome, eggs were activated by UV-irradiated sperm and exposed to one of the following shock treatments for inhibition of first mitosis: a combined ether-late pressure shock (CEP), a late heat shock (HS) and a late pressure shock without an additional ether treatment (LP). Each shock treatment was applied to egg batches produced by the same 16 females of each population. Haploid controls, chromosome preparations, recessive colour mutants and genetic markers were controls for the treatments. The CEP treatment was found to be the most effective with 30% of egg batches treated developing into swimup fry in both populations. For HS and LP, results were significantly poorer, reaching rates of 14% and 7%, respectively, in the gold-coloured population and no survival up to the swim-up stage in the wild population. A special sensibility or suitability of eggs derived from a particular female to HS or LP shock was observed. The repeated production of swim-up fry from eggs of the same female, especially in the CEP group, demonstrated the importance of the maternal genotype for obtaining viable homozygous gynogenetic offspring. All mature homozygous gynogenetic zebra fish obtained ( N=9) were males.