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James E Biardi - One of the best experts on this subject based on the ideXlab platform.
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isolation and identification of a snake venom metalloproteinase inhibitor from California Ground Squirrel spermophilus beecheyi blood sera
Toxicon, 2011Co-Authors: James E Biardi, J Marcinczyk, K P NambiarAbstract:California Ground Squirrels (Spermophilus beecheyi) show blood-based defenses to a variety of toxins in the venom of the Northern Pacific rattlesnake (Crotalus oreganus oreganus). In this study we demonstrate the presence of an effective snake venom metalloproteinase inhibitor (SVMPI) in S. beecheyi. The blood sera of California Ground Squirrels were effective at reducing the metalloproteinase activity of Northern Pacific (C. o. oreganus) and prairie rattlesnake (Crotalus viridis viridis) venoms by over 75%, significantly more than its ability to reduce the activity of western diamondback rattlesnake venom. We used anion exchange and affinity chromatography to isolate this protein from the blood sera of S. beecheyi. This SVMPI had a molecular mass of 108.3 kDa and a pI of 5.1. The IC(50) of this inhibitor against whole venom from C. o. oreganus was determined to be 3.14 × 10(-8) M. Subsequent LC MS/MS analysis of a CNBr/tryptic digest of the inhibitor yielded multiple internal peptide sequences. These sequences showed homology to three other known mammalian plasma proteins: inter-α trypsin inhibitor, and two hibernation-associated proteins, HP25 and HP27. The presence of SVMPI in S. beecheyi blood sera is consistent with the resistance of these animals to venom-induced hemorrhage and tissue damage, and consistent with the protective factors conferring venom resistance in other mammals. However, the variety of SVMPI identified to date from mammalian taxa suggests that different species have converged on neutralization of venom metalloproteinase activity as a key step in venom neutralization.
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California Ground Squirrel (Spermophilus beecheyi) Defenses Against Rattlesnake Venom Digestive and Hemostatic Toxins
Journal of Chemical Ecology, 2006Co-Authors: James E Biardi, David C. Chien, Richard G CossAbstract:Previous studies have shown that some mammals are able to neutralize venom from snake predators. California Ground Squirrels ( Spermophilus beecheyi ) show variation among populations in their ability to bind venom and minimize damage from northern Pacific rattlesnakes ( Crotalus oreganus ), but the venom toxins targeted by resistance have not been investigated. Four California Ground Squirrel populations, selected for differences in local density or type of rattlesnake predators, were assayed for their ability to neutralize digestive and hemostatic effects of venom from three rattlesnake species. In Douglas Ground Squirrels ( S. b. douglasii ), we found that animals from a location where snakes are common showed greater inhibition of venom metalloprotease and hemolytic activity than animals from a location where snakes are rare. Effects on general proteolysis were not different. Douglas Ground Squirrels also reduced the metalloprotease activity of venom from sympatric northern Pacific rattlesnakes ( C. o. oreganus ) more than the activity of venom from allopatric western diamondback rattlesnakes ( C. atrox ), but enhanced the fibrinolysis of sympatric venom almost 1.8 times above baseline levels. Two Beechey Ground Squirrel ( S. b. beecheyi ) populations had similar inhibition of venoms from northern and southern Pacific rattlesnakes ( C. o. helleri ), despite differences between the populations in the locally prevalent predator. However, the venom toxins inhibited by Beechey Squirrels varied among venom from Pacific rattlesnake subspecies, and between these venoms and venom from allopatric western diamondback rattlesnakes. Blood plasma from Beechey Squirrels showed highest inhibition of metalloprotease activity of northern Pacific rattlesnake venom, general proteolytic activity and hemolysis of southern Pacific rattlesnake venom, and hemolysis by allopatric western diamondback venom. These results reveal previously cryptic variation in venom activity against resistant prey that suggests reciprocal adaptation at the molecular level.
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California Ground Squirrel spermophilus beecheyi blood sera inhibits crotalid venom proteolytic activity
Toxicon, 2000Co-Authors: James E Biardi, Richard G Coss, David Glenn SmithAbstract:Some California Ground Squirrels (Spermophilus beecheyi) show limited necrosis following envenomation by northern Pacific rattlesnakes (Crotalus viridis oreganus). This study demonstrates that S. beecheyi blood sera inhibits venom proteases. Sera from rattlesnake-abundant habitats inhibited C. v. oreganus venom more effectively than venom from two allopatric rattlesnake species, C. v. viridis and C. atrox, suggesting evolutionary specialization. The pattern of inhibition among Squirrel populations corresponds best with history of rattlesnake predation, in contrast to current rattlesnake density.
Richard G Coss - One of the best experts on this subject based on the ideXlab platform.
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confronting snakes in the burrow snake species discrimination and antisnake tactics of two California Ground Squirrel populations
Ethology, 2010Co-Authors: Steven R Towers, Richard G CossAbstract:The purpose of this study was to investigate phylogenetic and ecological factors that shape encounters between California Ground Squirrels and snakes in the burrow setting. Ground Squirrels were video taped while interacting in a simulated burrow with either a venomous rattlesnake or a lessdangerous gopher snake. Squirrels from a population where snakes are rare treated both snake species with greater caution than did Squirrels from a snake-adapted population. High physiological resistance to rattlesnake venom in the snake-adapted population was associated with more intense rattlesnake harassment. Squirrels from both populations treated the rattlesnake as the more important predator, as inferred from higher levels of harassment and escape-motivated behavior while interacting with the rattlesnake. We conclude that the tightly constraining ecology of burrow encounters with intruders supports the expression of competent antipredator behavior in Ground Squirrels. We view adaptations such as snake-species discrimination as embedded in the ecological relationship between snakes, Ground Squirrels, and the architecture of the burrow setting.
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California Ground Squirrel (Spermophilus beecheyi) Defenses Against Rattlesnake Venom Digestive and Hemostatic Toxins
Journal of Chemical Ecology, 2006Co-Authors: James E Biardi, David C. Chien, Richard G CossAbstract:Previous studies have shown that some mammals are able to neutralize venom from snake predators. California Ground Squirrels ( Spermophilus beecheyi ) show variation among populations in their ability to bind venom and minimize damage from northern Pacific rattlesnakes ( Crotalus oreganus ), but the venom toxins targeted by resistance have not been investigated. Four California Ground Squirrel populations, selected for differences in local density or type of rattlesnake predators, were assayed for their ability to neutralize digestive and hemostatic effects of venom from three rattlesnake species. In Douglas Ground Squirrels ( S. b. douglasii ), we found that animals from a location where snakes are common showed greater inhibition of venom metalloprotease and hemolytic activity than animals from a location where snakes are rare. Effects on general proteolysis were not different. Douglas Ground Squirrels also reduced the metalloprotease activity of venom from sympatric northern Pacific rattlesnakes ( C. o. oreganus ) more than the activity of venom from allopatric western diamondback rattlesnakes ( C. atrox ), but enhanced the fibrinolysis of sympatric venom almost 1.8 times above baseline levels. Two Beechey Ground Squirrel ( S. b. beecheyi ) populations had similar inhibition of venoms from northern and southern Pacific rattlesnakes ( C. o. helleri ), despite differences between the populations in the locally prevalent predator. However, the venom toxins inhibited by Beechey Squirrels varied among venom from Pacific rattlesnake subspecies, and between these venoms and venom from allopatric western diamondback rattlesnakes. Blood plasma from Beechey Squirrels showed highest inhibition of metalloprotease activity of northern Pacific rattlesnake venom, general proteolytic activity and hemolysis of southern Pacific rattlesnake venom, and hemolysis by allopatric western diamondback venom. These results reveal previously cryptic variation in venom activity against resistant prey that suggests reciprocal adaptation at the molecular level.
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age differences in the response of California Ground Squirrels spermophilus beecheyi to conspecific alarm calls
Ethology, 2001Co-Authors: Mark T Hanson, Richard G CossAbstract:Juvenile California Ground Squirrel responses to adult alarm calls and juvenile alarm calling may be modified during development to achieve adult form. Adult conspecific chatter and whistle alarm calls were played back to juvenile and adult Ground Squirrels at an agricultural field site. In response to chatter playbacks, adults spent more time visually orienting to the environment and less time out of view and in covered habitats than juveniles: the converse was true in response to whistle playbacks. To test the evocativeness of juvenile calling, a subset of adult subjects received juvenile chatter and whistle playbacks. Adults spent less time out of view to juvenile call types than to adult calls, and showed more similar responses to juvenile chatters and whistles than to adult chatters and whistles. Age differences in the Ground Squirrel's alarm call system may reflect adjustments to changing risks during development.
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California Ground Squirrel spermophilus beecheyi blood sera inhibits crotalid venom proteolytic activity
Toxicon, 2000Co-Authors: James E Biardi, Richard G Coss, David Glenn SmithAbstract:Some California Ground Squirrels (Spermophilus beecheyi) show limited necrosis following envenomation by northern Pacific rattlesnakes (Crotalus viridis oreganus). This study demonstrates that S. beecheyi blood sera inhibits venom proteases. Sera from rattlesnake-abundant habitats inhibited C. v. oreganus venom more effectively than venom from two allopatric rattlesnake species, C. v. viridis and C. atrox, suggesting evolutionary specialization. The pattern of inhibition among Squirrel populations corresponds best with history of rattlesnake predation, in contrast to current rattlesnake density.
Desley A. Whisson - One of the best experts on this subject based on the ideXlab platform.
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use of zinc phosphide for California Ground Squirrel control
Proceedings of the Vertebrate Pest Conference, 2000Co-Authors: Terrell P Salmon, Desley A. Whisson, Paul W GorenzelAbstract:Author(s): Salmon, Terrell P.; Whisson, Desley A.; Gorenzel, W. Paul | Abstract: Zinc phosphide (ZnP) is the only acute rodenticide currently registered for control of the California Ground Squirrel (Spermophilus beecheyi). Research has shown ZnP to give excellent control of sciurid rodents, but operational control programs in California have reported poor and inconsistent control. We examined the literature and conducted 34 field trials between 1996 and 1999 in order to identify factors affecting the field efficacy of ZnP. Important factors identified from the literature include bait acceptance, prebaiting, and timing of control operations in relation to Ground Squirrel and vegetation phenology. We used Ground Squirrel counts or active burrow counts to assess the efficacy of ZnP in the field trials. Treatments were either mechanical broadcast or spot baiting of 2% ZnP-treated oat groats. The first field trials in 1996 and 1997 were conducted without bait acceptance tests and prebaiting, and control was inconsistent, ranging from none on one plot, poor on three plots (45% to 63%), to good on two plots (84% to 87%). Field trials in 1998 and 1999 were conducted with bait acceptance tests and pre-baiting. In 1998 control was excellent (88% to 100%) on all plots. However, control was variable in 1999 trials with good control (80% to 90%) on five plots, but poor control (60% to 79%) on two plots, and no control on one plot. In our studies, pre-baiting had little effect on the efficacy of the ZnP for controlling California Ground Squirrels.
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modified bait stations for California Ground Squirrel control in endangered kangaroo rat habitat
Wildlife Society Bulletin, 1998Co-Authors: Desley A. WhissonAbstract:The potential for using elevated bait stations for California Ground Squirrel (Spermophilus beecheyi) control in endangered kangaroo rat habitat was evaluated. Laboratory and field studies identified two bait-station designs that excluded kangaroo rats while allowing access by California Ground Squirrels. Traditional bait stations can be easily modified, thereby providing landowners with a method of controlling Ground Squirrels that mitigates hazards to endangered kangaroo rats.
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modified bait stations for California Ground Squirrel control in engangered kangaroo rat habitat
Proceedings of the Vertebrate Pest Conference, 1998Co-Authors: Desley A. WhissonAbstract:Author(s): Whisson, Desley A. | Abstract: California Ground Squirrels are a major problem in areas that also support populations of endangered kangaroo rats. Traditional bait stations can be easily modified to exclude kangaroo rats, thereby providing landowners with a method of controlling Ground Squirrels that mitigates hazards to endangered kangaroo rats. Specifications for the design and use of modified bait stations are discussed.
K P Nambiar - One of the best experts on this subject based on the ideXlab platform.
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isolation and identification of a snake venom metalloproteinase inhibitor from California Ground Squirrel spermophilus beecheyi blood sera
Toxicon, 2011Co-Authors: James E Biardi, J Marcinczyk, K P NambiarAbstract:California Ground Squirrels (Spermophilus beecheyi) show blood-based defenses to a variety of toxins in the venom of the Northern Pacific rattlesnake (Crotalus oreganus oreganus). In this study we demonstrate the presence of an effective snake venom metalloproteinase inhibitor (SVMPI) in S. beecheyi. The blood sera of California Ground Squirrels were effective at reducing the metalloproteinase activity of Northern Pacific (C. o. oreganus) and prairie rattlesnake (Crotalus viridis viridis) venoms by over 75%, significantly more than its ability to reduce the activity of western diamondback rattlesnake venom. We used anion exchange and affinity chromatography to isolate this protein from the blood sera of S. beecheyi. This SVMPI had a molecular mass of 108.3 kDa and a pI of 5.1. The IC(50) of this inhibitor against whole venom from C. o. oreganus was determined to be 3.14 × 10(-8) M. Subsequent LC MS/MS analysis of a CNBr/tryptic digest of the inhibitor yielded multiple internal peptide sequences. These sequences showed homology to three other known mammalian plasma proteins: inter-α trypsin inhibitor, and two hibernation-associated proteins, HP25 and HP27. The presence of SVMPI in S. beecheyi blood sera is consistent with the resistance of these animals to venom-induced hemorrhage and tissue damage, and consistent with the protective factors conferring venom resistance in other mammals. However, the variety of SVMPI identified to date from mammalian taxa suggests that different species have converged on neutralization of venom metalloproteinase activity as a key step in venom neutralization.
David Glenn Smith - One of the best experts on this subject based on the ideXlab platform.
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California Ground Squirrel spermophilus beecheyi blood sera inhibits crotalid venom proteolytic activity
Toxicon, 2000Co-Authors: James E Biardi, Richard G Coss, David Glenn SmithAbstract:Some California Ground Squirrels (Spermophilus beecheyi) show limited necrosis following envenomation by northern Pacific rattlesnakes (Crotalus viridis oreganus). This study demonstrates that S. beecheyi blood sera inhibits venom proteases. Sera from rattlesnake-abundant habitats inhibited C. v. oreganus venom more effectively than venom from two allopatric rattlesnake species, C. v. viridis and C. atrox, suggesting evolutionary specialization. The pattern of inhibition among Squirrel populations corresponds best with history of rattlesnake predation, in contrast to current rattlesnake density.
