Abstract
Based on the formation of an autotetraploid fish line (4nAUT, 4n = 200; F2–F11) derived from the distant hybridization of female Carassius auratus red var. (RCC, 2n = 100) × male Megalobrama amblycephala (BSB, 2n = 48), we produced autotriploid hybrids (3nAUT) by crossing females of RCC with males of 4nAUT and allotriploid hybrids (3nALT) by crossing females of Cyprinus carpio (CC, 2n = 100) with males of 4nAUT. The aim of this study was to comparatively investigate the reproductive characteristics of 3nALT and 3nAUT. We investigated morphological traits, chromosomal numbers, DNA content and gonadal development in 3nAUT and 3nALT. The results indicated both 3nAUT and 3nALT possessed 150 chromosomes and were triploid hybrids. The females and males of 3nALT and males of 3nAUT had abnormal gonadal development and could not generate mature eggs or sperm, but the females of 3nAUT had normal gonadal development and generated mature eggs at 2 years old. The females of 3nAUT generated different sizes of eggs, which fertilized with haploid sperm from RCC and formed viable diploid, triploid, and tetraploid offspring. The formation of these two kinds of triploid hybrids provides an ideal model for studying the reproductive traits of triploid hybrids, which is of great value in animal genetics and reproductive biology.
Highlights
Polyploids are organisms that normally have three or more chromosome sets
Allopolyploids possess a combination of chromosomes from two or more different species, while autopolyploids possess multiple chromosome sets mainly derived from a single taxon
The artificial induction of triploid fish is mainly used to improve quality associated with sexual maturation such as higher growth rates, stronger disease resistance, and better organoleptic properties
Summary
Polyploids are organisms that normally have three or more chromosome sets. Polyploidy is common in plants, and studies have shown that all angiosperms are ancient polyploids (Otto, 2007). As research continues, increasing evidence has shown that polyploids are widespread in animals and are mainly concentrated in amphibians, reptiles, and fishes (Mable, 2004; Gregory and Mable, 2005; Wertheim et al, 2013). Polyploids can be divided into autopolyploids and allopolyploids according to their origin of chromosome doubling. Allopolyploids possess a combination of chromosomes from two or more different species, while autopolyploids possess multiple chromosome sets mainly derived from a single taxon. Fish chromosomes display plasticity and produce polyploids more (Liu, 2010). The artificial induction of triploid fish is mainly used to improve quality associated with sexual maturation such as higher growth rates, stronger disease resistance, and better organoleptic properties
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