scholarly journals mRNA Stability and Polysome Loss in Hibernating Arctic Ground Squirrels (Spermophilus parryii)

2000 ◽  
Vol 20 (17) ◽  
pp. 6374-6379 ◽  
Author(s):  
Jason E. Knight ◽  
Erin Nicol Narus ◽  
Sandra L. Martin ◽  
Allan Jacobson ◽  
Brian M. Barnes ◽  
...  
Keyword(s):  
Mrna Stability ◽  
Functional Significance ◽  
Binding Protein ◽  
Ground Squirrels ◽  
Gene Products ◽  
Body Temperatures ◽  
Spermophilus Parryii ◽  
Torpor Bout ◽  
Arctic Ground Squirrels ◽  
The Stability

ABSTRACT All small mammalian hibernators periodically rewarm from torpor to high, euthermic body temperatures for brief intervals throughout the hibernating season. The functional significance of these arousal episodes is unknown, but one suggestion is that rewarming may be related to replacement of gene products lost during torpor due to degradation of mRNA. To assess the stability of mRNA as a function of the hibernation state, we examined the poly(A) tail lengths of liver mRNA from arctic ground squirrels sacrificed during four hibernation states (early and late during a torpor bout and early and late following arousal from torpor) and from active ground squirrels sacrificed in the summer. Poly(A) tail lengths were not altered during torpor, suggesting either that mRNA is stabilized or that transcription continues during torpor. In mRNA isolated from torpid ground squirrels, we observed a pattern of 12 poly(A) residues at greater densities approximately every 27 nucleotides along the poly(A) tail, which is a pattern consistent with binding of poly(A)-binding protein. The intensity of this pattern was significantly reduced following arousal from torpor and undetectable in mRNA obtained from summer ground squirrels. Analyses of polysome profiles revealed a significant reduction in polyribosomes in torpid animals, indicating that translation is depressed during torpor.

mRNA Stability and Polysome Loss in Hibernating Arctic Ground Squirrels (Spermophilus parryii)

2000 ◽  
Vol 20 (17) ◽  
pp. 6374-6379
Author(s):  
Jason E. Knight ◽  
Erin Nicol Narus ◽  
Sandra L. Martin ◽  
Allan Jacobson ◽  
Brian M. Barnes ◽  
...  
Keyword(s):  
Mrna Stability ◽  
Ground Squirrels ◽  
Spermophilus Parryii ◽  
Arctic Ground Squirrels

scholarly journals Habitat selection by arctic ground squirrels (Spermophilus parryii)

2010 ◽  
Vol 91 (5) ◽  
pp. 1251-1260 ◽  
Author(s):  
Oliver E. Barker ◽  
Andrew E. Derocher
Keyword(s):  
Habitat Selection ◽  
Ground Squirrels ◽  
Spermophilus Parryii ◽  
Arctic Ground Squirrels

scholarly journals Ascorbate dynamics and oxygen consumption during arousal from hibernation in Arctic ground squirrels

2001 ◽  
Vol 281 (2) ◽  
pp. R572-R583 ◽  
Author(s):  
Ø. Tøien ◽  
K. L. Drew ◽  
M. L. Chao ◽  
M. E. Rice
Keyword(s):  
Peak Plasma ◽  
Plasma Concentrations ◽  
Metabolic Stress ◽  
Ground Squirrels ◽  
Electromyographic Activity ◽  
Spermophilus Parryii ◽  
Plasma Ascorbate ◽  
Leukocyte Counts ◽  
Plasma Urate ◽  
Arctic Ground Squirrels

During hibernation in Arctic ground squirrels ( Spermophilus parryii), O2 consumption and plasma leukocyte counts decrease by >90%, whereas plasma concentrations of the antioxidant ascorbate increase fourfold. During rewarming, O2 consumption increases profoundly and plasma ascorbate and leukocyte counts return to normal. Here we investigated the dynamic interrelationships among these changes. Plasma ascorbate and uric acid (urate) concentrations were determined by HPLC from blood samples collected at ∼15-min intervals via arterial catheter; leukocyte count and hematocrit were also determined. Body temperature, O2 consumption, and electromyographic activity were recorded continuously. Ascorbate, urate, and glutathione contents in body and brain samples were determined during hibernation and after arousal. During rewarming, the maximum rate of plasma ascorbate decrease occurred at the time of peak O2 consumption and peak plasma urate production. The ascorbate decrease did not correlate with mouth or abdominal temperature; uptake into leukocytes could account for only a small percentage. By contrast, liver and spleen ascorbate levels increased significantly after arousal, which could more than account for ascorbate clearance from plasma. Brain ascorbate levels remained constant. These data suggest that elevated concentrations of ascorbate {[Asc]} in plasma {[Asc]p} provide an antioxidant source that is redistributed to tissues during the metabolic stress that accompanies arousal.

Effects of food and predators on the home-range sizes of Arctic ground squirrel (Spermophilus parryii)

1998 ◽  
Vol 76 (3) ◽  
pp. 592-596 ◽  
Author(s):  
Anne H Hubbs ◽  
Rudy Boonstra
Keyword(s):  
Home Range ◽  
Ground Squirrel ◽  
Large Scale ◽  
Yukon Territory ◽  
Ground Squirrels ◽  
Home Ranges ◽  
Spermophilus Parryii ◽  
Mammalian Predators ◽  
Core Areas ◽  
Arctic Ground Squirrels

We used radiotelemetry to study the effects of food addition and predator reduction on the home-range sizes of adult Arctic ground squirrels (Spermophilus parryii) on large-scale experimental grids in the boreal forest of the southwestern Yukon Territory. Home ranges were 2-7 times smaller on food-supplemented grids than on nonsupplemented grids, regardless of whether large mammalian predators were present. Similarly, core areas (where 50% of activities occur) were 8-11 times smaller on food-supplemented grids. Food availability rather than predator presence primarily determined the sizes of home ranges and core areas of Arctic ground squirrels.

scholarly journals An mRNA Stability Complex Functions with Poly(A)-Binding Protein To Stabilize mRNA In Vitro

1999 ◽  
Vol 19 (7) ◽  
pp. 4552-4560 ◽  
Author(s):  
Zuoren Wang ◽  
Nancy Day ◽  
Panayiota Trifillis ◽  
Megerditch Kiledjian
Keyword(s):  
Mrna Stability ◽  
Binding Protein ◽  
Major Protein ◽  
Globin Mrna ◽  
Ideal System ◽  
Complex Functions ◽  
Cytosolic Extract ◽  
Protein Components ◽  
The Stability

ABSTRACT The stable globin mRNAs provide an ideal system for studying the mechanism governing mammalian mRNA turnover. α-Globin mRNA stability is dictated by sequences in the 3′ untranslated region (3′UTR) which form a specific ribonucleoprotein complex (α-complex) whose presence correlates with mRNA stability. One of the major protein components within this complex is a family of two polycytidylate-binding proteins, αCP1 and αCP2. Using an in vitro-transcribed and polyadenylated α-globin 3′UTR, we have devised an in vitro mRNA decay assay which reproduces the α-complex-dependent mRNA stability observed in cells. Incubation of the RNA with erythroleukemia K562 cytosolic extract results in deadenylation with distinct intermediates containing a periodicity of approximately 30 nucleotides, which is consistent with the binding of poly(A)-binding protein (PABP) monomers. Disruption of the α-complex by sequestration of αCP1 and αCP2 enhances deadenylation and decay of the mRNA, while reconstitution of the α-complex stabilizes the mRNA. Similarly, PABP is also essential for the stability of mRNA in vitro, since rapid deadenylation resulted upon its depletion. An RNA-dependent interaction between αCP1 and αCP2 with PABP suggests that the α-complex can directly interact with PABP. Therefore, the α-complex is an mRNA stability complex in vitro which could function at least in part by interacting with PABP.

The influence of herbivores and neighboring plants on risk of browsing: a case study using arctic lupine (Lupinus arcticus) and arctic ground squirrels (Spermophilus parryii plesius)

2001 ◽  
Vol 79 (5) ◽  
pp. 874-880 ◽  
Author(s):  
Leonardo Frid ◽  
Roy Turkington
Keyword(s):  
Plant Density ◽  
Plant Morphology ◽  
Ground Squirrels ◽  
Individual Plant ◽  
Resource Concentration ◽  
Spermophilus Parryii ◽  
Increased Risk ◽  
Arctic Ground Squirrels ◽  
A Site ◽  
Palatable Species

We examined how herbivore distribution and density, neighboring plant density and species composition, and individual plant morphology all influence the risk that individual arctic lupines (Lupinus arcticus) will be browsed by arctic ground squirrels (Spermophilus parryii plesius). Risk of being browsed was significantly influenced by the number of resident ground squirrels but not by overall squirrel density at a site. As the leaf density of neighboring conspecifics increased, risk of browsing to an individual lupine decreased except when palatable neighbors were also present. The presence of other palatable species increased the risk of browsing. Risk was highest when both lupine and other palatable neighbors were present. The presence of unpalatable neighbors reduced the risk of browsing of individual lupines. We discuss these results in the context of three hypotheses: (1) attractant decoy, (2) resource concentration, and (3) repellent plant. No single hypothesis accounts for our observations, but an interaction between herbivores, neighbors, and individual lupine morphology determined risk of browsing.

scholarly journals Insular arctic ground squirrels (Spermophilus parryii) of the North Pacific: indigenous or exotic?

2010 ◽  
Vol 91 (6) ◽  
pp. 1401-1412 ◽  
Author(s):  
Joseph A. Cook ◽  
Aren A. Eddingsaas ◽  
Janet L. Loxterman ◽  
Steve Ebbert ◽  
S. O. MacDonald
Keyword(s):  
North Pacific ◽  
Ground Squirrels ◽  
Spermophilus Parryii ◽  
The North ◽  
Arctic Ground Squirrels ◽  
The North Pacific
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