Changes in Energy Reserves and Gene Expression Elicited by Freezing and Supercooling in the Antarctic Midge, <i>Belgica antarctica</i>
Freeze-tolerance, or the ability to survive internal ice formation, is relatively rare among insects. Larvae of the Antarctic midge <i>Belgica antarctica</i> are freeze-tolerant year-round, but in dry environments, the larvae can remain supercooled (i.e., unfrozen) at subzero temperature...
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MDPI AG
2019-12-01
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| Series: | Insects |
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| Online Access: | https://www.mdpi.com/2075-4450/11/1/18 |
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| author | Nicholas M. Teets Emma G. Dalrymple Maya H. Hillis J. D. Gantz Drew E. Spacht Richard E. Lee David L. Denlinger |
| author_facet | Nicholas M. Teets Emma G. Dalrymple Maya H. Hillis J. D. Gantz Drew E. Spacht Richard E. Lee David L. Denlinger |
| author_sort | Nicholas M. Teets |
| collection | DOAJ |
| description | Freeze-tolerance, or the ability to survive internal ice formation, is relatively rare among insects. Larvae of the Antarctic midge <i>Belgica antarctica</i> are freeze-tolerant year-round, but in dry environments, the larvae can remain supercooled (i.e., unfrozen) at subzero temperatures. In previous work with summer-acclimatized larvae, we showed that freezing is considerably more stressful than remaining supercooled. Here, these findings are extended by comparing survival, tissue damage, energetic costs, and stress gene expression in larvae that have undergone an artificial winter acclimation regime and are either frozen or supercooled at −5 °C. In contrast to summer larvae, winter larvae survive at −5 °C equally well for up to 14 days, whether frozen or supercooled, and there is no tissue damage at these conditions. In subsequent experiments, we measured energy stores and stress gene expression following cold exposure at −5 °C for either 24 h or 14 days, with and without a 12 h recovery period. We observed slight energetic costs to freezing, as frozen larvae tended to have lower glycogen stores across all groups. In addition, the abundance of two heat shock protein transcripts, <i>hsp60</i> and <i>hsp90</i>, tended to be higher in frozen larvae, indicating higher levels of protein damage following freezing. Together, these results indicate a slight cost to being frozen relative to remaining supercooled, which may have implications for the selection of hibernacula and responses to climate change. |
| first_indexed | 2024-12-10T21:36:59Z |
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| language | English |
| last_indexed | 2024-12-10T21:36:59Z |
| publishDate | 2019-12-01 |
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| record_format | Article |
| series | Insects |
| spelling | doaj.art-8929f600815748b69138538d4b98383d2022-12-22T01:32:36ZengMDPI AGInsects2075-44502019-12-011111810.3390/insects11010018insects11010018Changes in Energy Reserves and Gene Expression Elicited by Freezing and Supercooling in the Antarctic Midge, <i>Belgica antarctica</i>Nicholas M. Teets0Emma G. Dalrymple1Maya H. Hillis2J. D. Gantz3Drew E. Spacht4Richard E. Lee5David L. Denlinger6Department of Entomology, University of Kentucky, Lexington, KY 40546, USADepartment of Entomology, University of Kentucky, Lexington, KY 40546, USADepartment of Entomology, University of Kentucky, Lexington, KY 40546, USABiology Department, Hendrix College, Conway, AK 72032, USADepartment of Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43210, USADepartment of Biology, Miami University, Oxford, OH 45056, USADepartment of Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43210, USAFreeze-tolerance, or the ability to survive internal ice formation, is relatively rare among insects. Larvae of the Antarctic midge <i>Belgica antarctica</i> are freeze-tolerant year-round, but in dry environments, the larvae can remain supercooled (i.e., unfrozen) at subzero temperatures. In previous work with summer-acclimatized larvae, we showed that freezing is considerably more stressful than remaining supercooled. Here, these findings are extended by comparing survival, tissue damage, energetic costs, and stress gene expression in larvae that have undergone an artificial winter acclimation regime and are either frozen or supercooled at −5 °C. In contrast to summer larvae, winter larvae survive at −5 °C equally well for up to 14 days, whether frozen or supercooled, and there is no tissue damage at these conditions. In subsequent experiments, we measured energy stores and stress gene expression following cold exposure at −5 °C for either 24 h or 14 days, with and without a 12 h recovery period. We observed slight energetic costs to freezing, as frozen larvae tended to have lower glycogen stores across all groups. In addition, the abundance of two heat shock protein transcripts, <i>hsp60</i> and <i>hsp90</i>, tended to be higher in frozen larvae, indicating higher levels of protein damage following freezing. Together, these results indicate a slight cost to being frozen relative to remaining supercooled, which may have implications for the selection of hibernacula and responses to climate change.https://www.mdpi.com/2075-4450/11/1/18antarcticafreeze-toleranceenergy storesheat shock proteins<i>belgica antarctica</i> |
| spellingShingle | Nicholas M. Teets Emma G. Dalrymple Maya H. Hillis J. D. Gantz Drew E. Spacht Richard E. Lee David L. Denlinger Changes in Energy Reserves and Gene Expression Elicited by Freezing and Supercooling in the Antarctic Midge, <i>Belgica antarctica</i> Insects antarctica freeze-tolerance energy stores heat shock proteins <i>belgica antarctica</i> |
| title | Changes in Energy Reserves and Gene Expression Elicited by Freezing and Supercooling in the Antarctic Midge, <i>Belgica antarctica</i> |
| title_full | Changes in Energy Reserves and Gene Expression Elicited by Freezing and Supercooling in the Antarctic Midge, <i>Belgica antarctica</i> |
| title_fullStr | Changes in Energy Reserves and Gene Expression Elicited by Freezing and Supercooling in the Antarctic Midge, <i>Belgica antarctica</i> |
| title_full_unstemmed | Changes in Energy Reserves and Gene Expression Elicited by Freezing and Supercooling in the Antarctic Midge, <i>Belgica antarctica</i> |
| title_short | Changes in Energy Reserves and Gene Expression Elicited by Freezing and Supercooling in the Antarctic Midge, <i>Belgica antarctica</i> |
| title_sort | changes in energy reserves and gene expression elicited by freezing and supercooling in the antarctic midge i belgica antarctica i |
| topic | antarctica freeze-tolerance energy stores heat shock proteins <i>belgica antarctica</i> |
| url | https://www.mdpi.com/2075-4450/11/1/18 |
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