Polyploid gibel carp has been revealed to possess coexisting dual modes of unisexual gynogenesis and sexual reproduction and to have numerous various clones. Using sexual reproduction mating between clone D female and clone A male and subsequent 7 generation multiplying of unisexual gynogenesis, researchers from Institute of Hydrobiology, Chinese Academy of Sciences (IHB), led by Prof. GUI Jianfang, Principal Investigator of the Research Group of Fish Developmental Genetics and Cell Engineering, have created a novel clone strain with more than several hundred millions of individuals.  

IHB researchers use several nuclear genome markers and one cytoplasmic marker, the mitochondrial genome sequence to identify the genetic organization of the randomly sampled individuals from different generations of the novel clone. Chromosome number, Cot-1 repetitive DNA banded karyotype, microsatellite patterns, AFLP profiles and transferrin alleles uniformly indicated that nuclear genome of the novel clone is identical to that of clone A, and significantly different from that of clone D. However, the cytoplasmic marker, its complete mtDNA genome sequence, is same to that of clone D, and different from that of clone A.  

The present data indicate that the novel clone is a nucleo-cytoplasmic hybrid between the known clones A and D, because it originates from the offspring of gonochoristic sexual reproduction mating between clone D female and clone A male, and contains an entire nuclear genome from the paternal clone A and a mtDNA genome (cytoplasm) from the maternal clone D. It is suggested to arise via androgenesis by a mechanism of ploidy doubling of clone A sperm in clone D ooplasm through inhibiting the first mitotic division. Significantly, the selected nucleo-cytoplasmic hybrid female still maintains its gynogenetic ability.  

The present and previous findings help to get better insights into the association of rapid genetic changes and high genetic diversity with various ploidy levels and multiple reproduction modes in several unisexual and sexual complexes of vertebrates and even other invertebrates. Additionally, as the nucleo-cytoplasmic hybrid clone escapes the genetic and developmental destruction caused by drastic treatments of irradiation and physical shocks in induced androgenesis and nuclear transplantation, the novel finding will be of great significance for exploiting the genetic breeding approaches in gibel carp. 

This work was supported by the earmarked fund for Modern Agro-industry Technology Research System, the National Key Basic Research Program and the National Natural Science Foundation of China. The peer-reviewed article was published online in the journal BMC Research Notes (http://www.biomedcentral.com/1756-0500/4/82/).