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Baker M.J.,Eastern Washington University | Baker M.J.,Center for Animals Near Biological Extinction | Denton T.T.,Eastern Washington University | Herr C.,Eastern Washington University | Herr C.,Center for Animals Near Biological Extinction
Cryobiology | Year: 2013

Slush nitrogen (SN) is used to avoid the Leidenfrost effect, which is problematic when using liquid nitrogen (LN). Slush nitrogen's usefulness has been demonstrated by its requirement for the successful cryopreservation of insect embryos. To convert LN to SN, typically, the pressure above a Dewar of LN is reduced, using a vacuum pump in a sealed system until conversion occurs. It has been observed that LN from a fresh tank will readily produce SN; however, repeated use of the same LN results in the inability to form SN in subsequent trials. The current experiments were designed to identify the cause of this phenomenon. The hypothesis is that gaseous oxygen from the surrounding, ambient air condenses and mixes with the LN to form a mixture with a lower freezing point and; therefore, prevents the formation of SN. The hypothesis was tested and found to be true. © 2012.

Hopkins B.K.,Washington State University | Herr C.,Center for Animals Near Biological Extinction | Sheppard W.S.,Washington State University
Reproduction, Fertility and Development | Year: 2012

Much of the world's food production is dependent on honey bees for pollination, and expanding food production will further increase the demand for managed pollination services. Apiculturists outside the native range of the honey bee, in the Americas, Australia and eastern Asia, have used only a few of the 27 described subspecies of honey bees (Apis mellifera) for beekeeping purposes. Within the endemic ranges of a particular subspecies, hybridisation can threaten native subspecies when local beekeepers import and propagate non-native honey bees. For many threatened species, cryopreserved germplasm can provide aresource for the preservation ofdiversity and recovery of endangered populations. However, although instrumental insemination ofqueen honey beesiswell established, the absence of aneffective means to cryopreserve honey bee semen has limited the success of efforts to preserve genetic diversity within the species or to develop repositories of honey bee germplasm for breeding purposes. Herein we report that some queens inseminated with cryopreserved semen were capable of producing a substantial number of fertilised offspring. These diploid female larvae were usedtoproduce two additional sequential generations ofnew queens, which were then back-crossed to the same stock of frozen semen. Our results demonstrate the ability to produce queens using cryopreserved honey bee spermatozoa and the potential for the establishment of a honey bee genetic repository. © CSIRO 2012.

Hopkins B.K.,Center for Animals Near Biological Extinction | Herr C.,Center for Animals Near Biological Extinction
Apidologie | Year: 2010

This report is about cryopreservation of honey bee semen. There has been little advancement of this technology over the past 20 years. Cytotoxicity of the cryoprotectants, temperature sensitivity, freezing rate, and cold shock were investigated. The least toxic cryoprotectant was DMSO. Spermatozoa were tolerant to temperatures up to 40 °C. A programmable freezing rate of 3 °C/min proved superior in most treatments when compared to a freezing rate of approximately 28000 °C/min. Highest viability of spermatozoa (93%) post cryopreservation resulted from the treatment containing a 10% DMSO diluent, slow cooled to just above freezing, and frozen at a rate of 3 °C/min. Spermatozoa frozen in such a manner yielded viability and motility indistinguishable from that of unfrozen semen. Promising results warrant a field study. © 2010 INRA/DIB-AGIB/EDP Sciences.

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