Comparative studies of sperm cryopreservation of diploid and tetraploid Pacific Oysters
This dissertation addressed comparative studies of sperm cryopreservation of diploid and tetraploid Pacific oysters, Crassostrea gigas, with an emphasis on the development of standardized and optimized protocols. This includes comparative ultrastructural differences between sperm from diploid and te...
| Main Author: | |
|---|---|
| Format: | Text |
| Language: | unknown |
| Published: |
LSU Digital Commons
2005
|
| Subjects: | |
| Online Access: | https://digitalcommons.lsu.edu/gradschool_dissertations/3817 https://doi.org/10.31390/gradschool_dissertations.3817 https://digitalcommons.lsu.edu/context/gradschool_dissertations/article/4816/viewcontent/uc.pdf |
| Summary: | This dissertation addressed comparative studies of sperm cryopreservation of diploid and tetraploid Pacific oysters, Crassostrea gigas, with an emphasis on the development of standardized and optimized protocols. This includes comparative ultrastructural differences between sperm from diploid and tetraploid oysters, methods for the rapid estimation of sperm concentration, optimization of cryopreservation, and evaluation of the mechanisms for sperm agglutination (formation of clumps or elongated "noodles") in thawed samples. Currently, cryopreserved sperm has not been commercialized in any aquatic species, and standardization and optimization could greatly benefit the potential commercialization of its use. In oysters specifically, cryopreserved sperm from tetraploids would facilitate the production of all-triploid seedstocks. In this study, sperm from tetraploid oysters were 25% larger in linear dimensions (lengths and widths), and 53% had 5 mitochondria compared to 4 in diploids. Spectrophotometric methods for rapid estimation of sperm concentration were developed and validated. The effects of cooling rate, single or combined cryoprotectants at various concentrations, equilibration time (exposure to cryoprotectant), straw size, and cooling method were evaluated for protocol optimization. Combination of the cryoprotectants polyethylene glycol (PEG; formula weight of 200) and methanol (for sperm from diploids) or PEG and propylene glycol (for sperm from tetraploids) were effective in retaining post-thaw motility only when PEG was at low concentrations (2-6%). Such effectiveness was especially manifested with sperm from tetraploids, for example, post-thaw motility as high as 50% was obtained with combined cryoprotectant. Sperm of tetraploid Pacific oysters were more susceptible to damage from cryopreservation procedures than were those of diploids, and male-to-male variation was significant for sperm from diploid and tetraploid oysters. Sperm agglutination was mainly due to the lack of sufficient cryoprotectant ... |
|---|