Regain of sex determination system and sexual reproduction ability in a synthetic octoploid male fish

Abstract

Polyploids in vertebrates are generally associated with unisexual reproduction, but the direct consequences of polyploidy on sex determination system and reproduction mode remain unknown. Here, we synthesized a group of artificial octoploids between unisexual gynogenetic hexaploid Carassius gibelio and sexual tetraploid Carassius auratus. The synthetic octoploids were revealed to have more than 200 chromosomes, in which 50 chromosomes including the X/Y sex determination system were identified to transfer from sexual tetraploid C. auratus into the unisexual gynogenetic hexaploid C. gibelio. Significantly, a few synthetic octoploid males were found to be fertile, and one octoploid male was confirmed to regain sexual reproduction ability, which exhibits characteristics that are the same to sexual reproduction tetraploid males, such as 1:1 sex ratio occurrence, meiosis completion and euploid sperm formation in spermatogenesis, as well as normal embryo development and gene expression pattern during embryogenesis. Therefore, the current finding provides a unique case to explore the effect of sex determination system incorporation on reproduction mode transition from unisexual gynogenesis to sexual reproduction along with genome synthesis of recurrent polyploidy in vertebrates.

Divergent Antiviral Mechanisms of Two Viperin Homeologs in a Recurrent Polyploid Fish

“…Viperin was sharply upregulated among three clones at post infection ( 52 ). Additionally, gibel carp has over 150 chromosomes and is considered an auto-allo-hexaploid in comparison with goldfish ( Carassius auratus ) with 100 chromosomes ( 53 , 54 ). It had been speculated that two rounds (2R) of polyploidy events, an allotetraploidy and an autotriploidy, occurred during its evolution ( 55 ).…”

Dynamic and Differential Expression of Duplicated Cxcr4/Cxcl12 Genes Facilitates Antiviral Response in Hexaploid Gibel Carp

“…Polyploidy is considered as a major driver of species diversification and frequently occurred during teleost evolution ( 25 , 57 , 58 ). Although the consequences are complex and variable, it might increase short-term adaptive potential and long-term evolvability for polyploid organisms along with subsequent rediploidization ( 59 – 61 ).…”

Simple Field Storage of Fish Samples for Measurement of DNA Content by Flow Cytometry

“…Ploidy determination based on estimate of relative DNA content is a common application of flow cytometry in fish research. Recent examples include study of the sex determination system and the reproductive ability of a synthetic octoploid male arising from two Carassius species (53) and triploidy induction by hydrostatic pressure shock in Mandarin fish Siniperca chuatsi (54) and sterlet (55).…”