Production of tetraploids by introduction of sperm nucleus into the eggs of gynogenetic triploid ginbuna Carassius langsdorfii

摘要

Tetraploid and tertraploid-triploid mosaic fish were successfully produced in gynogenetically reproducing triploid ginbuna Carassius langsdorfii by treating the eggs with various conditions of cold and heat shock after fertilization. Tetraploid fishwere detected in the progeny developed from the eggs which were treated by heat shock (40 deg C, 60s duration) in the period starting from 5 to 95 min after fertilization. The heat shock starting from 5 min after fertilization gave 67-100 percent tetraploidy. The patterns of DNA fingerprinting and RAPD-PCR in the tetraploid and tetraploid-triploid mosaic progeny consisted of all fragments identical to those of the mother triploid ginbuna and additional fragments derived from the father goldfish. Cytological observation on the eggs which were treated by heat shock (40 deg C, 60s) at 5 min after fertilization suggested that tetraploids are formed by fusing triploid female pronucleus and haploid male pronucleus, which is genetically inactive in triploidginbuna but active to form male pronucleus by the treatment. No significant difference was observed in the growth between triploid and tetraploid of 12-month-old fish reared with communal condition. All the triploid progeny examined were female. However,in the tetraploid progeny 10 out of 17 individuals were female, whereas the other 7 individuals were sexually indifferentiated.