Aberrant meioses and viable aneuploid progeny of induced triploid loach (Misgurnus anguillicaudatus) when crossed to natural tetraploids

Abstract In induced triploid loach Misgurnus anguillicaudatus , both bivalents and univalents were observed in the early pachytene stage of oocytes and they then degenerated in the late pachytene stage. Only a few yolk-laden oocytes were occasionally observed in the ovaries of triploids. Spermatocytes of triploid males formed both bivalents and univalents, and they developed to aneuploid spermatozoa. Flow cytometry revealed that the modal DNA content of these spermatozoa was 1.3C. These spermatozoa were able to fertilize the eggs of natural tetraploids (4 n ×3 n ) and the resultant aneuploid progeny showed chromosome numbers and DNA contents between triploidy and tetraploidy. These aneuploid progeny exhibited poorer survival than control triploids and tetraploids and most fry died before feeding due to severe malformation. However, those fry which began to feed survived. The average body length of one-month-old survivors was not different between aneuploids and tetraploids, but aneuploids showed significantly larger variance than the control.