Induction of diploid gynogenesis in an evolutionary model organism, the three-spined stickleback (Gasterosteus aculeatus)

Here, we present the first successful induction of diploid gynogenesis in an evolutionary model system, the three-spined sticklebacks (Gasterosteus aculeatus), using a combination of UV-irradiation of the sperm and heat shock (HS) of the resulting embryo to inhibit the second meiotic division. Optimal UV irradiation of the sperm was established by exposing stickleback sperm to a UV- light source at various times. Heat shock parameters like temperature, duration, and time of initiation were tested by subjecting eggs fertilized with UV inactivated sperm 5, 10, 15, 20, 25, or 30 minutes post fertilization (mpf) to 30°C, 34°C, or 38°C for 2, 4, 6 or 8 minutes. Gynogen yield was highest when stickleback eggs were activated with 2 minutes UV-irradiated sperm and received HS 5 mpf at 34°C for 4 minutes.Diploid gynogenesis has been successfully performed in three-spined stickleback. This has been confirmed by microsatellite DNA analysis which revealed exclusively maternal inheritance in all gynogenetic fry tested. Ploidy verification by flow cytometry showed that gynogenetic embryos/larvae exhibiting abnormalities were haploids and those that developed normally were diploids, i.e., double haploids that can be raised until adult size.The genomics community has been enormously revolutionized by first- and next generation sequencing (NGS) technologies [1-3] that generated vast amounts of genetic data ranging from unicellular (bacteria) to multicellular (eukaryotic) genomes. However, no matter how good these technologies are, polymorphisms in a genome complicate the assembly process, results in lower quality, and the contiguity and completeness of assembly is significantly lower than would be expected from a homozygous template [4]. Hence, there is a growing interest for the development of inbred lines, such as haploid and double haploid (DH) lines, which are particularly advantageous in genomics [5,6] because of their homozygosity and their growth potential. Inbred lines are a