No description available.

This study investigated alarm calls given by Uinta ground squirrels (Spermophilus armatus) in the presence of a ground predator. I observed predator responses of 18 groups of three to four squirrels each for an average of three trials apiece. r~y objectives were: (1) to describe prey-predator interactions resulting in alarm calls, and (2) to test the following hypotheses: 1. Each Uinta ground squirrel (by sex and age) has an equal probability of giving an alarm call at any time of the season. 2. All Uinta ground squirrels are equally likely to call regardless of their distance to a burrow, closest conspecific, and the predator. 3. Alarm calls are as likely to occur in the search stage of predation as in the pursuit stage. 4. Callers and noncallers are equally vulnerable to predation. I found that: ( 1) each Uinta ground squirrel (by sex and age) in the experimental population had an equal probability of giving an alarm call in the presence of a predator through the season, (2) callers and noncallers were equally close to burrows at the time of the call, (3) the caller was typically located farther away from its closest conspecific than noncallers at the time of the cal l, (4) the caller was significantly closer to the predator than were noncallers at the time of the call, (5) alarm calls occurred significantly more often in the pursuit stage of predation than in the search stage, and (6) noncallers suffered significantly more predation than did callers. There appeared to be little risk and energetic cost associated with calling. Squirrels that called usually were being pursued by the predator and were very close to a burrow when they called. The callers had little to lose and could increase their inclusive fitness by warning relatives of the presence of danger. This study dealt only with responses to ground predators. Squirrels are likely to respond differently to avian predators. It is suggested that responses of animals to avian and terrestrial predators should vary with the potential threat that the predator poses. The apparent inhibition of secondary calls is discussed. Once animals are aware of the presence of danger, there is no need for another animal to repeat the message and reveal its location to the predator.

Call number: LD2668 .T4 1937 E41

Richardson ground squirrels (gophers) are pests on the prairies that cause considerable agricultural and ecological damage. Traditional control methods such as the rodenticides strychnine, zinc phosphide, and anticoagulants, have proven ineffective in reducing gopher densities. In additional, current gopher control methods have the significant potential to cause primary and secondary toxicity to non-target animals. Thus, alternative methods for toxicological control of gophers are needed to mitigate these concerns. Present studies focused on the cytochrome P450 (CYP450) enzyme system responsible for xenobiotic detoxification in gophers. In vitro hepatic microsomal systems and HPLC analysis were used to elucidate general metabolic characteristics of major gopher xenobiotic metabolizing pathways. We found that the content and activity of individual components of the CYP450 system including CYP450, cytochrome b5, and NADPH-cytochrome P450 reductase in liver microsomal preparations were higher in gophers exposed to toxins used to control their population than in naïve (unexposed) gophers. When in vitro CYP450 mediated activities for five substrates [coumarin and aniline aromatic hydroxylation, 7-methoxycouamrin O-demethylation, and N-methylaniline, and N,N-dimethylaniline N-demethylation] were measured, naïve gophers were identified to have higher specific activity but similar whole body activity compared to the exposed gophers. Furthermore, there was a clearly identifiable sub-population of poor metabolizers showing considerably lower CYP450 activity within the gopher samples studied. Clotrimazole was found to be a potent inhibitor of several substrates of CYP450 enzyme-mediated reactions, which included aniline aromatic hydroxylation, N-methylaniline and N,N-dimethylaniline N-demethylation, and 7-methoxycoumarin O-demethylation. The cytotoxicity of above compounds was tested using freshly isolated gopher hepatocytes. The results showed that each compound caused considerable cytotoxicity to gopher hepatocytes. Addition of clotrimazole to the freshly isolated hepatocyte suspension increased the cytotoxicity of all tested compounds. <p>In conclusion, gophers may develop resistance to current chemical control methods through the enhancement of CYP450 system content, which can compensate the loss of enzyme activity. Furthermore, clotrimazole is a potent cytochrome P450 inhibitor, which increases the cytotoxicity caused by given compounds in gopher livers. The concept of using CYP450 enzyme inhibitor in combination with another chemical whose elimination depends on CYP450 metabolism to improve current gopher control method has practical importance.

Richardson ground squirrels (gophers) are pests on the prairies that cause considerable agricultural and ecological damage. Traditional control methods such as the rodenticides strychnine, zinc phosphide, and anticoagulants, have proven ineffective in reducing gopher densities. In additional, current gopher control methods have the significant potential to cause primary and secondary toxicity to non-target animals. Thus, alternative methods for toxicological control of gophers are needed to mitigate these concerns. Present studies focused on the cytochrome P450 (CYP450) enzyme system responsible for xenobiotic detoxification in gophers. In vitro hepatic microsomal systems and HPLC analysis were used to elucidate general metabolic characteristics of major gopher xenobiotic metabolizing pathways. We found that the content and activity of individual components of the CYP450 system including CYP450, cytochrome b5, and NADPH-cytochrome P450 reductase in liver microsomal preparations were higher in gophers exposed to toxins used to control their population than in naïve (unexposed) gophers. When in vitro CYP450 mediated activities for five substrates [coumarin and aniline aromatic hydroxylation, 7-methoxycouamrin O-demethylation, and N-methylaniline, and N,N-dimethylaniline N-demethylation] were measured, naïve gophers were identified to have higher specific activity but similar whole body activity compared to the exposed gophers. Furthermore, there was a clearly identifiable sub-population of poor metabolizers showing considerably lower CYP450 activity within the gopher samples studied. Clotrimazole was found to be a potent inhibitor of several substrates of CYP450 enzyme-mediated reactions, which included aniline aromatic hydroxylation, N-methylaniline and N,N-dimethylaniline N-demethylation, and 7-methoxycoumarin O-demethylation. The cytotoxicity of above compounds was tested using freshly isolated gopher hepatocytes. The results showed that each compound caused considerable cytotoxicity to gopher hepatocytes. Addition of clotrimazole to the freshly isolated hepatocyte suspension increased the cytotoxicity of all tested compounds. <p>In conclusion, gophers may develop resistance to current chemical control methods through the enhancement of CYP450 system content, which can compensate the loss of enzyme activity. Furthermore, clotrimazole is a potent cytochrome P450 inhibitor, which increases the cytotoxicity caused by given compounds in gopher livers. The concept of using CYP450 enzyme inhibitor in combination with another chemical whose elimination depends on CYP450 metabolism to improve current gopher control method has practical importance.

No description available.

No description available.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1934. / Reprinted from American journal of anatomy, vol. 54, no. 3 (15 May 1934). Title from title screen (viewed Mar. 22, 2007). Includes bibliographical references (p. 506). Online version of the print original.

No description available.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1934. / Reprinted from American journal of anatomy, vol. 54, no. 3 (15 May 1934). Includes bibliographical references (p. 506).