The formation of improved tetraploid population of red crucian carp × common carp hybrids by androgenesis

Abstract

Bisexual fertile diploid androgenetic individuals (A(0)) (2n=100) were formed by androgenesis. In this way, the diploid spermatozoa from male allotetraploid hybrids (AT) (4n=200) of red crucian carp (Carassius auratus red var.) (female) x common carp (Cyprinus carpio L.) (male) were used to fertilize the UV-treated haploid eggs of goldfish (Carassius auratus), and living androgenetic diploid fish were developed. The A(0) became sexually mature at the age of 2 years, and they fertilized with each other to form their offspring (A(1)). In this study, we observed the chromosomal number, gonadal structure and appearance of A(1) fish. The results are as follows: (1) In A(1), there were 85% tetraploids (A(1)-4n), 10% triploids (A(1)-3n) and 5% diploids (A(1)-2n), suggesting that diploid A(0) could produce diploid gametes. It was concluded that the formation of diploid gametes generated from diploid A(0) was probably related to the mechanism of pre-meiotic endoreduplication. (2) Among A(1), only A(1)-4n possessed normal ovaries and testes. The mature males of A1-4n produced white semen. Under the electron microscope, the head of diploid sperm generated by A(1)-4n was bigger than that of haploid sperm generated by red crucian carp. In the testes of the A(1)-4n, there were many mature normal spermatozoa with a head bearing plasma membrane and a tail having the typical structure of "9+2" microtubules. Between the head and the tail, there were some mitochondria. The ovaries of A(1)-4n developed well and mainly contained II, III and IV-stage oocytes. The IV-stage oocytes were surrounded by inner and outer follicular cells. The micropyle was observed on the oolemma of follicular cells. There were abundant yolks and plenty of endoplasmic reticulum in the cytoplasm of IV-stage oocytes. Because A(1)-2n and A(1)-3n were distant crossing diploid hybrids and triploid hybrids respectively, they possessed abnormal gonads, and no mature semen and eggs were observed. (3) Compared with allotetraploids, the A(1)-4n fish not only had advantages such as fast growth rate and strong resistibility but also showed some new good performances such as high ratio of body width to body length, smaller heads and shorter tails. These results indicated that androgenesis could produce bisexual fertile tetraploids and improve the shape of allotetraploid hybrids as well, which will be of great significance in both the cell genetics research and fish breeding.

Development and application of biological technologies in fish genetic breeding

“…Diploid androgenetic fish were self-crossed to obtain bisexual fertile tetraploids. When compared with ordinary allotetraploid hybrids, the new-type tetraploid fish exhibited significant growth advantages and increased disease resistance [115,116]. Additionally, using diploid sperms produced by autotetraploid males, we obtained super-male diploid fish from offspring that can produce unreduced diploid sperm.…”

Distant hybridization leads to different ploidy fishes

“…The males and females of A 0 reached sexual maturity at the age of 2 years. Improved tetraploids (4n=200) were obtained by mating the males with the females of A 0 , suggesting that diploid sperm and diploid eggs were respectively generated by the males and females of A 0 [41,42].…”

Horizontal gene transfers and cell fusions in microbiology, immunology and oncology (Review)

“…The insect's salivary gland epithelial cells migrate to their location only after myoblasts, longitudinal muscle founder cells and other mesenchymal cells fused and provided the proper integrins (258,259). Interspecies hybridization by cell fusion in fishes (carp) resulted in allo-tetraplod hybrid cells of great significance in genetic research for fish breeding (260), Plant (Solanum) mesophyll cell protoplasts can be fused in vitro with PEG (polyethylene glycol), remain stable as tetra-to decaploid cells, grow in soil, set flowers and bear parthenocarpic (virgin fruit) berries (261)(262)(263). This technology is applicable to many fruit-bearing plants.…”