An improved triploid crucian carp(ITCC) was produced by crossing improved tetraploids(G1×AT,) with improved red crucian carp(IRCC,),which were obtained by distant crossing and gynogenesis.The biological characteristics of ITCC,including the number and karyotype of chromosomes,gonadad and pituitary structures,phenotype,and growth rate are reported.ITCC possessed 150 chromosomes with the karyotype 33m+51sm+33st+33t.In the breeding season,both ovary-like and testis-like gonads of ITCC were unable to produce normal mature gametes.The ultrastructure of the pituitary of ITCC showed that most of the endocrine granules in gonadotrophic hormone(GTH) cells had not been released,providing endocrinological evidence for the sterility of ITCC.Compared with triploid crucian carp(TCC) produced by mating Japanese crucian carp with allotetraploid hybrids,ITCC not only retained the excellent traits of fast growth rate and sterility,but also acquired improved morphological characteristics,including higher body,shorter tail and smaller head.
CHEN Song,WANG Jing,LIU ShaoJun,QIN QinBo,XIAO Jun,DUAN Wei,LUO KaiKun,LIU JinHui & LIU Yun Key Laboratory of Protein Chemistry and Developmental Biology of State Education Ministry of China,College of Life Sciences,Hunan Normal University,Changsha 410081,China
Triploid carp(100%)with 150(3n=150)chromosomes were obtained by crossing the females of improved tetraploid hybrids(♀, 4n=200)of red crucian carp(♀)×common carp(♂)with the males of diploid yellow river carp(♂,2n=100).The crosses yielded transgenic triploid carp(positive triploid fish,44.2%of the progeny)and non-transgenic triploid carp(negative triploid fish). Histological examination of the gonads of 24-month-old positive triploid fish suggested they were sterile and the fish were not able to produce mature gametes during the breeding season.Morphologically,both the positive and negative triploid fish were similar.They had a spindle-shaped,laterally compressed,steel grey body with two pairs of barbells.Most of the quantifiable traits of the triploid carp were intermediate between those of the two parents.The positive and negative triploid fish were raised in the same pond for 2 years.The mean body weight of the positive triploid fish was 2.3 times higher than the negative triploid fish.The weight of the largest positive triploid fish was 2.91 times higher than that of the largest negative triploid fish.Thus,we produced fast-growing transgenic triploid carp that have a reduced ecological risk because of their inability to mate and produce progeny.
