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Effects of Mild and Low Temperature Incubation on Heat Tolerance in Bombyx mori Embryos

Received: 28 May 2018    Accepted: 19 June 2018    Published: 12 July 2018
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Abstract

Object: For ectothermic insects, thermal tolerance is one of the most essential properties for survival in ambient environments. However, the molecular mechanisms involved in thermal tolerance in the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) have not been fully elucidated. The present study investigated mechanisms that provide heat tolerance in embryos of Bombyx mori. Materials and Methods: Eggs of the bivoltine silkworm strain p50 were exposed to different temperatures, to determine the lethal threshold temperature and to assess the effects of mild and low temperature incubation on tolerance to heat shock and on embryonic protein profiles. Protein levels were measured by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Results: When eggs were exposed to transient heat shock for one hour, the lethal threshold temperature was between 47.0°C and 48.0°C. However, exposure to 40.0°C for four hours, substantially elevated tolerance to the threshold heat shock and simultaneously increased levels of 70 and 27 kDa proteins in eggs, whereas exposure to 35.0°C did not. Exposure to 10.0°C for four hours lowered heat tolerance and did not alter the expression of 70 and 27 kDa proteins. Conclusion: The present findings indicated that hardening silkworm eggs at mild temperatures increases heat tolerance in embryos. To our knowledge this is the first observation of heat hardening in silkworm embryos. These putative heat-shock proteins of 70 and 27 kDa might be involved in the effect of mild temperature hardening on heat tolerance. Cold stress might deprive embryos of energy reserves available for protection against heat damage. Protective mechanisms against heat and cold stress are probably different in this species. Further studies of the molecular mechanisms of heat tolerance should provide insight into the development of novel, high-yield silkworm strains in tropical environments.

Published in American Journal of Entomology (Volume 2, Issue 2)
DOI 10.11648/j.aje.20180202.11
Page(s) 6-9
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2024. Published by Science Publishing Group

Keywords

Embryo, Heat Shock Protein, Silkworm, Thermal Tolerance

References
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    Daisuke Matsuoka, Katsuhiko Sakamoto. (2018). Effects of Mild and Low Temperature Incubation on Heat Tolerance in Bombyx mori Embryos. American Journal of Entomology, 2(2), 6-9. https://doi.org/10.11648/j.aje.20180202.11

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    Daisuke Matsuoka; Katsuhiko Sakamoto. Effects of Mild and Low Temperature Incubation on Heat Tolerance in Bombyx mori Embryos. Am. J. Entomol. 2018, 2(2), 6-9. doi: 10.11648/j.aje.20180202.11

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    AMA Style

    Daisuke Matsuoka, Katsuhiko Sakamoto. Effects of Mild and Low Temperature Incubation on Heat Tolerance in Bombyx mori Embryos. Am J Entomol. 2018;2(2):6-9. doi: 10.11648/j.aje.20180202.11

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  • @article{10.11648/j.aje.20180202.11,
      author = {Daisuke Matsuoka and Katsuhiko Sakamoto},
      title = {Effects of Mild and Low Temperature Incubation on Heat Tolerance in Bombyx mori Embryos},
      journal = {American Journal of Entomology},
      volume = {2},
      number = {2},
      pages = {6-9},
      doi = {10.11648/j.aje.20180202.11},
      url = {https://doi.org/10.11648/j.aje.20180202.11},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.aje.20180202.11},
      abstract = {Object: For ectothermic insects, thermal tolerance is one of the most essential properties for survival in ambient environments. However, the molecular mechanisms involved in thermal tolerance in the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) have not been fully elucidated. The present study investigated mechanisms that provide heat tolerance in embryos of Bombyx mori. Materials and Methods: Eggs of the bivoltine silkworm strain p50 were exposed to different temperatures, to determine the lethal threshold temperature and to assess the effects of mild and low temperature incubation on tolerance to heat shock and on embryonic protein profiles. Protein levels were measured by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Results: When eggs were exposed to transient heat shock for one hour, the lethal threshold temperature was between 47.0°C and 48.0°C. However, exposure to 40.0°C for four hours, substantially elevated tolerance to the threshold heat shock and simultaneously increased levels of 70 and 27 kDa proteins in eggs, whereas exposure to 35.0°C did not. Exposure to 10.0°C for four hours lowered heat tolerance and did not alter the expression of 70 and 27 kDa proteins. Conclusion: The present findings indicated that hardening silkworm eggs at mild temperatures increases heat tolerance in embryos. To our knowledge this is the first observation of heat hardening in silkworm embryos. These putative heat-shock proteins of 70 and 27 kDa might be involved in the effect of mild temperature hardening on heat tolerance. Cold stress might deprive embryos of energy reserves available for protection against heat damage. Protective mechanisms against heat and cold stress are probably different in this species. Further studies of the molecular mechanisms of heat tolerance should provide insight into the development of novel, high-yield silkworm strains in tropical environments.},
     year = {2018}
    }
    

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  • TY  - JOUR
    T1  - Effects of Mild and Low Temperature Incubation on Heat Tolerance in Bombyx mori Embryos
    AU  - Daisuke Matsuoka
    AU  - Katsuhiko Sakamoto
    Y1  - 2018/07/12
    PY  - 2018
    N1  - https://doi.org/10.11648/j.aje.20180202.11
    DO  - 10.11648/j.aje.20180202.11
    T2  - American Journal of Entomology
    JF  - American Journal of Entomology
    JO  - American Journal of Entomology
    SP  - 6
    EP  - 9
    PB  - Science Publishing Group
    SN  - 2640-0537
    UR  - https://doi.org/10.11648/j.aje.20180202.11
    AB  - Object: For ectothermic insects, thermal tolerance is one of the most essential properties for survival in ambient environments. However, the molecular mechanisms involved in thermal tolerance in the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) have not been fully elucidated. The present study investigated mechanisms that provide heat tolerance in embryos of Bombyx mori. Materials and Methods: Eggs of the bivoltine silkworm strain p50 were exposed to different temperatures, to determine the lethal threshold temperature and to assess the effects of mild and low temperature incubation on tolerance to heat shock and on embryonic protein profiles. Protein levels were measured by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Results: When eggs were exposed to transient heat shock for one hour, the lethal threshold temperature was between 47.0°C and 48.0°C. However, exposure to 40.0°C for four hours, substantially elevated tolerance to the threshold heat shock and simultaneously increased levels of 70 and 27 kDa proteins in eggs, whereas exposure to 35.0°C did not. Exposure to 10.0°C for four hours lowered heat tolerance and did not alter the expression of 70 and 27 kDa proteins. Conclusion: The present findings indicated that hardening silkworm eggs at mild temperatures increases heat tolerance in embryos. To our knowledge this is the first observation of heat hardening in silkworm embryos. These putative heat-shock proteins of 70 and 27 kDa might be involved in the effect of mild temperature hardening on heat tolerance. Cold stress might deprive embryos of energy reserves available for protection against heat damage. Protective mechanisms against heat and cold stress are probably different in this species. Further studies of the molecular mechanisms of heat tolerance should provide insight into the development of novel, high-yield silkworm strains in tropical environments.
    VL  - 2
    IS  - 2
    ER  - 

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Author Information
  • Biosignal Research Center, Kobe University, Kobe, Japan

  • Biosignal Research Center, Kobe University, Kobe, Japan; Graduate School of Agricultural Science, Kobe University, Kobe, Japan

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