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SUMMARY Most aquatic insects do not survive subzero temperatures and, for those that do, the physiology has not been well characterized. Nemoura arctica is a species of stonefly widely distributed throughout arctic and subarctic Alaska. We collected nymphs from the headwaters of the Chandalar River,...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.1086.9558 2023-05-15T15:09:38+02:00 _ Kent R Walters Jr Todd Sformo Brian M Barnes John G Duman The Pennsylvania State University CiteSeerX Archives 2009 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1086.9558 http://www.iab.uaf.edu/people/brian_barnes/publications/2009_Walters_etal.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1086.9558 http://www.iab.uaf.edu/people/brian_barnes/publications/2009_Walters_etal.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.iab.uaf.edu/people/brian_barnes/publications/2009_Walters_etal.pdf text 2009 ftciteseerx 2020-05-24T00:16:03Z SUMMARY Most aquatic insects do not survive subzero temperatures and, for those that do, the physiology has not been well characterized. Nemoura arctica is a species of stonefly widely distributed throughout arctic and subarctic Alaska. We collected nymphs from the headwaters of the Chandalar River, where we recorded streambed temperatures as low as -12.7°C in midwinter. When in contact with ice, autumn-collected N. arctica cool to -1.5±0.4°C before freezing, but individuals survived temperatures as low as -15°C, making this the first described species of freeze-tolerant stonefly. N. arctica clearly survive freezing in nature, as winter-collected nymphs encased in ice demonstrated high survivorship when thawed. In the laboratory, 87% of N. arctica nymphs frozen to -15°C for 2.5 weeks survived and, within one month of thawing, 95% of the last-instar nymphs emerged. N. arctica produce both glycerol and ice-binding factors (e.g. antifreeze protein) in response to low temperature. Hemolymph glycerol concentrations increased from 3 mmol l -1 to 930±114 mmol l -1 when temperatures were decreased from 4°C to -8°C, and N. arctica continued to produce glycerol even while frozen. Although the hemolymph of individual cold-acclimated nymphs occasionally exhibited more than a degree of thermal hysteresis, typically the hemolymph exhibited only hexagonal crystal growth, indicating a low concentration of ice-binding factor. Hemolymph of nymphs acclimated to subzero temperatures had recrystallization inhibition. These results demonstrate that, in the face of freezing conditions, N. arctica exhibit overwintering adaptations similar to those of terrestrial insects. Text Arctic Subarctic Alaska Unknown Arctic Midwinter ENVELOPE(139.931,139.931,-66.690,-66.690) |
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ftciteseerx |
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English |
description |
SUMMARY Most aquatic insects do not survive subzero temperatures and, for those that do, the physiology has not been well characterized. Nemoura arctica is a species of stonefly widely distributed throughout arctic and subarctic Alaska. We collected nymphs from the headwaters of the Chandalar River, where we recorded streambed temperatures as low as -12.7°C in midwinter. When in contact with ice, autumn-collected N. arctica cool to -1.5±0.4°C before freezing, but individuals survived temperatures as low as -15°C, making this the first described species of freeze-tolerant stonefly. N. arctica clearly survive freezing in nature, as winter-collected nymphs encased in ice demonstrated high survivorship when thawed. In the laboratory, 87% of N. arctica nymphs frozen to -15°C for 2.5 weeks survived and, within one month of thawing, 95% of the last-instar nymphs emerged. N. arctica produce both glycerol and ice-binding factors (e.g. antifreeze protein) in response to low temperature. Hemolymph glycerol concentrations increased from 3 mmol l -1 to 930±114 mmol l -1 when temperatures were decreased from 4°C to -8°C, and N. arctica continued to produce glycerol even while frozen. Although the hemolymph of individual cold-acclimated nymphs occasionally exhibited more than a degree of thermal hysteresis, typically the hemolymph exhibited only hexagonal crystal growth, indicating a low concentration of ice-binding factor. Hemolymph of nymphs acclimated to subzero temperatures had recrystallization inhibition. These results demonstrate that, in the face of freezing conditions, N. arctica exhibit overwintering adaptations similar to those of terrestrial insects. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Kent R Walters Jr Todd Sformo Brian M Barnes John G Duman |
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Kent R Walters Jr Todd Sformo Brian M Barnes John G Duman _ |
author_facet |
Kent R Walters Jr Todd Sformo Brian M Barnes John G Duman |
author_sort |
Kent R Walters Jr |
title |
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publishDate |
2009 |
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http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1086.9558 http://www.iab.uaf.edu/people/brian_barnes/publications/2009_Walters_etal.pdf |
long_lat |
ENVELOPE(139.931,139.931,-66.690,-66.690) |
geographic |
Arctic Midwinter |
geographic_facet |
Arctic Midwinter |
genre |
Arctic Subarctic Alaska |
genre_facet |
Arctic Subarctic Alaska |
op_source |
http://www.iab.uaf.edu/people/brian_barnes/publications/2009_Walters_etal.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1086.9558 http://www.iab.uaf.edu/people/brian_barnes/publications/2009_Walters_etal.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766340790787768320 |