Triploids have become an important part of the oyster aquaculture industry. Triploids can be produced by two methods: (1) inhibiting polar body II in normal zygotes; and (2) mating diploids and tetraploids. Both methods can theoretically generate some incidental aneuploids, which in higher animals are often lethal or associated with growth retardation. In this study, we investigated the occurrence of aneuploids in three replicates of a normal diploid group (2N), a cytochalasin B induced triploid (3nCB) and a mated triploid group from diploid female x tetraploid male mating (3nDT), and documented their growth performance. No aneuploids were found in normal diploid groups, and all diploid oysters had exactly the expected diploid number -20 chromosomes. Two of the 90 oysters (2.2%) from 3nCB groups were aneuploids: one with 19 chromosomes (2n - 1) and one with 29 chromosomes (3n - 1). In 3nDT groups, 18 of the 90 oysters (20%) were aneuploids, which included two oysters with 28 chromosomes (3n - 2), 10 with 29 chromosomes (3n - 1) and six with 31 chromosomes (3n + 1). The large numbers of aneuploids from 3nDT groups suggested that meiosis in paternal tetraploids was prone to segregation error. Triploids from 3nDT groups were significantly bigger than normal diploids and 3nCB triploids. Aneuploids were not significantly different from 3nDT triploids in body size. But like 3nDT triploids, aneuploids as a group were significantly bigger than normal diploids and 3nCB triploids. Results of this study support our previous finding that oysters tolerate a number of aneuploid conditions without obvious growth retardation. Certain aneuploids such as monosomics (2n - 1) and trisomics (2n + l) should be useful for genomic dissection and QTL analyses.
All Science Journal Classification (ASJC) codes
- Aquatic Science
- Gene mapping