Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Life Sciences
Biochemistry Of Trehalose Accumulation In The Spring Field Cricket, Gryllus Veletis, Alyssa R. Stephens
Biochemistry Of Trehalose Accumulation In The Spring Field Cricket, Gryllus Veletis, Alyssa R. Stephens
Electronic Thesis and Dissertation Repository
The freeze tolerant spring field cricket, Gryllus veletis, accumulates trehalose in the blood and tissues during cold acclimation. Trehalose is the main blood sugar in insects, thus its blood concentration is tightly regulated, and trehalose is readily metabolized. How do crickets modify their metabolism to accumulate trehalose in their hemolymph and tissues? I hypothesized that trehalose production, transport, and consumption were modified during the cold acclimation to facilitate trehalose accumulation. Trehalose and the trehalose-specific transporter, TRET-1, are distributed among all tissues, and trehalose accumulates in the hemolymph, fat body, Malpighian tubules, and gut. Trehalose production increases during cold acclimation …
Freeze Tolerance In The Spring Field Cricket, Gryllus Veletis, Alexander H. Mckinnon
Freeze Tolerance In The Spring Field Cricket, Gryllus Veletis, Alexander H. Mckinnon
Electronic Thesis and Dissertation Repository
Many insects are able to survive internal ice formation. However, the mechanisms underlying freeze tolerance are not well-understood, perhaps because of a lack of suitable model organisms. I found that the spring field cricket, Gryllus veletis, seasonally acquires freeze tolerance in the fall when kept outside in London, Ontario. Moreover, individuals acquired freeze tolerance in the laboratory in response to a simulated fall thermophotoperiod. Lab-acclimated G. veletis freeze at -6.1 ± 0.7 ºC and the acquisition of freeze tolerance is accompanied by the accumulation of proline and trehalose. Crickets survived temperatures as low as -12 ºC (1.5 h), and …
The Sub-Lethal Effects Of Repeated Cold Exposure In Insects, Katie Elizabeth Marshall
The Sub-Lethal Effects Of Repeated Cold Exposure In Insects, Katie Elizabeth Marshall
Electronic Thesis and Dissertation Repository
While insect cold tolerance has been well studied, the vast majority of work has focused on the effects of a single cold exposure. However, many abiotic environmental stresses, including temperature, fluctuate within an organism's lifespan. In this thesis I address two major questions. First, does frequency of cold exposure impose additional stress on insects? Second, how does this stress translate to performance and fitness? I first summarize the literature on the effects of repeated cold exposure in insects, critically examining experimental designs. I then address my questions experimentally using four insect species with contrasting life histories and responses to cold …
Cold Tolerance Of Each Life Stage Of The Sub-Alpine Willow Leaf Beetle, Chrysomela Aeneicollis, Evelyn C. Boychuk
Cold Tolerance Of Each Life Stage Of The Sub-Alpine Willow Leaf Beetle, Chrysomela Aeneicollis, Evelyn C. Boychuk
Electronic Thesis and Dissertation Repository
To understand the potential effects of climate change on the sub-alpine willow leaf beetle, the cold tolerance strategy and mechanisms involved in cold tolerance were investigated for all life stages. Microhabitat choice and microclimate temperatures within each microhabitat were related to median lethal temperature for each life stage. Summer active and quiescent adults are freeze tolerant, eggs and pupae are freeze avoidant and all larval stages are chill susceptible. Quiescent adults accumulated the highest concentration of glycerol (~24 mM) and haemolymph osmolality (875 mOsm). Haemolymph from pupae had angular crystals suggestive of antifreeze agent activity, but this was absent in …