Tolerance of the freeze-dried mouse sperm nucleus to temperatures ranging from \u2212196\u2009\xb0C to 150\u2009\xb0C

Sayaka Wakayama,Masatoshi Ooga,Satoshi Kishigami,Daiyu Ito,Shigenobu Yonemura,Teruhiko Wakayama,Yuko Kamada

doi:10.1038/s41598-019-42062-8

Sayaka Wakayama, Masatoshi Ooga + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-42062-8

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Abstract

It has long been believed that tolerance against extreme environments is possible only for ‘lower’ groups, such as archaea, bacteria or tardigrades, and not for more ‘advanced’ species. Here, we demonstrated that the mammalian sperm nucleus also exhibited strong tolerance to cold and hot temperatures. When mouse spermatozoa were freeze-dried (FD), similar to the anhydrobiosis of Tardigrades, all spermatozoa were ostensibly dead after rehydration. However, offspring were obtained from recovered FD sperm nuclei, even after repeated treatment with conditions from liquid nitrogen to room temperature. Conversely, when FD spermatozoa were heated at 95 °C, although the birth rate was decreased with increasing duration of the treatment, offspring were obtained even for FD spermatozoa that had been heat-treated for 2 h. This period was improved up to 6 h when glucose was replaced with trehalose in the freeze-drying medium, and the resistance temperature was extended up to 150 °C for short periods of treatment. Randomly selected offspring grew into healthy adults. Our results suggest that, when considering the sperm nucleus/DNA as the material that is used as a blueprint of life, rather than cell viability, a significant tolerance to extreme temperatures is present even in ‘higher’ species, such as mammals.

Highlights

It is well known that tolerance to extreme environments is observed in archaea and bacteria and in tardigrades and the larvae of Chironomids1
These findings suggest that, the entire mammalian body is susceptible to extreme environments, its cell nuclei can retain vital potential and that healthy offspring can be generated from them using recent reproductive biotechnology
The examination of FD spermatozoa immediately after freeze-drying treatment revealed that, none of them survived after rehydration (Fig. 1b–d; Supplemental Table 1), healthy offspring could be obtained after their microinjection into fresh oocytes

Summary

Introduction

It is well known that tolerance to extreme environments is observed in archaea and bacteria and in tardigrades and the larvae of Chironomids. We and others have demonstrated that the complete drying of mammalian spermatozoa—similar to the anhydrobiotic state of Tardigrades—allowed their preservation even at room temperature without losing their potential for supporting development after fertilization11–15 These findings suggest that, the entire mammalian body is susceptible to extreme environments, its cell nuclei can retain vital potential and that healthy offspring can be generated from them using recent reproductive biotechnology. The mouse strain sources for the spermatozoa were: BD, BDF1; BC, BCF1; and B6, C57BL/6N For these reasons, in this study, we attempted to generate offspring from spermatozoa treated with low temperature, frequent temperature changes or high temperature and determined the limits of tolerance of the sperm nucleus after freeze-drying

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Results

Conclusion