Preservation of silkworm strains is currently being carried out at the egg stage due to the dormancy of Bombyx mori at that life history stage.
However, the period of viable preservation is limited to just one year.
The development of safe and long-term preservation methods for a variety of silkworm strains has been an outstanding issue.
Cryopreservation is currently used for ovaries as part of the NBRP’s second phase of activities, but there is still a need to develop further improvements for the preservation of the male silkworm genome.
The main focus of our research is the development of long-term preservation methods for male silkworm germplasms.
Specifically, we are developing technologies for long-term cryopreservation of male germ cells (spermatogonia/spermatocytes) by building upon cryopreservation technologies developed originally for silkworm ovaries.
To test one method planned for the preservation of male germ cells, we plan to extract the spermatogonia/spermatocytes from the selected strain by utilizing a miniscule glass tube.
We will then freeze the extracted germ cells using liquid nitrogen and then transplant the thawed cells into a host silkworm’s testes for preservation.
Following this, we plan to collect the transplanted germ cells from the host testes.
The other planned preservation method involves the extraction and freezing of undifferentiated larvae testes that are then thawed and transplanted into a host.
To facilitate the simultaneous preservation of male and female germplasms, as well as fertilized eggs, we are considering the implementation of a new freezing method called CAS (Cells Alive System).