Publications

influence of light irradiance on hydroxyindole-o-methyltransferase activity, serotonin-n-acetyltransferase activity, and radioimmunoassayable melatonin levels in the pineal gland of the diurnally active richardson's ground squirrel.	when richardson's ground squirrels were kept under light:dark cycles of 14:10 h there was no nocturnal rise in pineal hydroxyindole-o-methyltransferase (hiomt) activity. conversely, the 10 h dark period was associated with large nocturnal rises in both pineal serotonin-n-acetyltransferase (nat) activity and radioimmunoassayable melatonin levels. the nighttime rises in pineal nat and melatonin were not suppressed by the exposure of the animals to a light irradiance of 925 mu w/cm2 during the norm ...	1983	6686468
pathology of sarcocystis campestris infection in richardson's ground squirrels (spermophilus richardsoni).	richardson's ground squirrels were infected with 1500 or 9000 sporocysts of sarcocystis campestris from badgers. no lesions were found in animals killed one to three days postinfection (pi). hepatitis and phlebitis of hepatic veins were present in animals killed between four and eight days pi. no meronts were detected in these animals, but the lesions suggested that a generation of merogony occurred in the hepatic veins. meronts were found in endothelial cells in many tissues beginning on day 9 ...	1983	6411306
seasonal variations in drug response and staircase phenomena in atrial muscle from a hibernating rodent (spermophilus richardsonii).	1 electrically driven atrial muscle from a hibernating rodent (spermophilus richardsonii) showed marked seasonal variations in inotropic responsiveness to both the cardiac glycoside actodigin and to raised extracellular calcium concentration. in contrast, glycoside toxicity was apparent and comparable in all tissues. 2 these variations were accompanied by changes in force-frequency ('staircase') characteristics of the tissues. 3 in contrast, no seasonal variation was observed in either positive ...	1983	6297645
thyroidal iodine and thyroglobulin in hibernating and active richardson's ground squirrels spermophilus richardsoni.	thyroidal iodine, protein and thyroglobulin (tg) were investigated in a hibernator, spermophilus richardsoni, sampled in the field and from laboratory-held winter colonies. in field animals, thyroidal iodine and protein contents were similar at onset of hibernation and at terminal arousal. iodine content was increased in laboratory-held animals, a function of alimentary supply, but no differences were observed between hibernators and non-hibernators. density sucrose gradients showed that approx. ...	1983	6135544
seasonally-related physiological and behavioural changes in captive richardson's ground squirrels (spermophilus richardsoni).	1. this study reveals the interrelationship among body weight, food intake and activity for a one-year period in two different year groups of captive juvenile richardson's ground squirrels (spermophilus richardsoni). 2. an increase in body weight during initial captivity and during the post-hibernation period related to an increase in food intake and in activity. 3. high and constant body weights during the pre-hibernation seasons were associated with a "voluntary" reduction in food intake, a de ...	1983	6131779
pinealectomy in ground squirrels: effect on behavioral and physiological responses to heat stress.	richardson's ground squirrels, 1 year after pinealectomy, showed altered behavioral and physiological responses to heat stress when compared to an intact group. pinealectomized squirrels bar-pressed more often for a cool temperature reward in a hot environment. when deprived of behavioral control of the hot environment, pinealectomized squirrels increased their oxygen consumption, had a higher body temperature, and displayed signs of greater thermal stress, including death, as compared to intact ...	1982	7079365
studies on the regulation of pineal melatonin production in the richardson's ground squirrel (spermophilus richardsonii).	the acute exposure of wild-captured richardson's ground squirrels to fluorescent light (intensity = 370-400 ftc) at 2400h, 4 hours after the onset of darkness, was followed by a slight depression in the activity of pineal n-acetyltransferase (nat); during the same 60 min period, pineal melatonin levels were not inhibited. conversely, when laboratory-raised squirrels were either exposed to light at night or kept in their normal period of darkness, pineal nat activity and melatonin levels differed ...	1982	7202215
the effects of the light:dark cycle and sympathetically-active drugs on pineal n-acetyltransferase activity and melatonin content in the richardson's ground squirrel, spermophilus richardsonii.	when adult richardson's ground squirrels, born in the wild, are kept in the laboratory under light:dark cycles of 14:10 (lights out at 2000 h), pineal n-acetyltransferase (nat) activity and melatonin levels begin to rise shortly after lights out; both reach peak levels by 4 h into the dark phase. the rise in pineal nat activity is partially blocked by phentolamine, an alpha-receptor blocker, and totally blocked by propranolol, a beta-receptor blocker. phentolamine had no inhibitory influence on ...	1982	7202214
day-night differences in the number of pineal "synaptic" ribbons in two diurnal rodents, the chipmunk (tamias striatus) and the ground squirrel (spermophilus richardsonii).	daytime numbers of pineal "synaptic" ribbons higher than reported in the pineal gland of any other mammalian species were observed in two diurnal rodents, the eastern chipmunk and richardson's ground squirrel. the number of "synaptic" ribbons was lower during the daytime and higher at night in both of these species.	1982	6889463
the ecology of colorado tick fever in rocky mountain national park in 1974. ii. infection in small mammals.	field studies of colorado tick fever (ctf) in small mammals in rocky mountain national park (rmnp) in 1974 established that eutamias minimus and spermophilus lateralis were the most important hosts for ctf virus and were the source of virus for immature stages of the tick vector, dermacentor andersoni. other species (peromyscus maniculatus, spermophilus richardsonii, eutamias umbrinus) are secondary hosts. the intensity of viral activity in rodents varied greatly from locality to locality. highe ...	1981	6263122
experimental colorado tick fever virus infection in colorado mammals.	one hundred and twenty-four small mammals of six species were inoculated with three strains of colorado tick fever (ctf) virus to define viremia and neutralizing (n) antibody responses. adult eutamias minimus and eutamias embrinus, and juvenile peromyscus maniculatus and spermophilus lateralis, were highly susceptible to development of viremic infection. adult s. lateralis and p. maniculatus were moderately susceptible (greater than or equal to 50% viremic). five sylvilagus nuttalli did not beco ...	1981	6259958
hibernation in thyroidectomized ground squirrels, spermophilus richardsoni.		1981	7227815
absence of evidence for a hibernation "trigger" in blood dialyzate of richardson's ground squirrel.		1979	477365
effects of central injection of biogenic amines during arousal from hibernation.	simultaneous measurements of heat production (hp) and heat loss (hl) and brain and rectal temperatures were made in richardon's ground squirrels (spermophilus richardsonii) rewarming from hibernation at an ambient temperature of 6.0 +/- 0.5 degrees c. calculations from hp and hl measurements from control animals showed that due to differential rewarming, there was a reduction of apparent specific heat of the animal to 0.59 cal/g. degrees c. this resulted in an energy saving of 30%. three intrace ...	1979	426092
effect of age and parity on weight gain and entry into hibernation in richardson's ground squirrels.		1978	751708
thyroxine metabolism in active and torpid ground squirrels, spermophilus richardsoni.		1978	658662
studies on immunoglobulins of richardson's ground squirrel--i. characterization of ground squirrel igg.		1978	640712
variations in (na+ + k+)-atpase and mg2+-atpase activity of the ground squirrel brain during hibernation.	1. the specific activity of brain (na+ + k+)-atpase and mg2+ -atpase of the ground squirrel (spermophilus richardsonii) is significantly increased after long-term hibernation. 2. the markedly non-linear thermal dependence of (na+ + k+)-atpase is unchanged during hibernation whereas the near linear thermal dependence of mg2+-atpase undergoes minor alteration after prolonged hibernation. 3. the sensitivity of (na+ + k+)-atpase to inhibition by ouabain is significantly decreased after 100 days of h ...	1978	233776
seasonal variations in the renal cortical (na+ + k+)-atpase and mg2+-atpase of a hibernator, the ground squirrel (spermophilus richardsonii).	1. the specific activity of renal cortical (na+ + k+)-atpase of the richardson ground squirrel is markedly reduced during hibernation, in contrast to the specific activity of the accompanying mg2+-atpase which is markedly increased. 2. the sensitivity of (na+ + k+)-atpase to inhibition by ouabain is unchanged by hibernation. 3. both the non-linear thermal dependence of (na+ + k+)-atpase and the linear thermal dependence of mg2+-atpase are also unchanged by hibernation. 4. the energy of activatio ...	1978	233796
serum t4 and t3 in active and torpid ground squirrels, spermophilus richardsoni.		1978	566236
intranasal exposure of the richardson's ground squirrel to western equine encephalomyelitis virus.	adult richardson's ground squirrels were infected with western equine encephalomyelitis virus by intranasal instillation. mortality followed the instillation of a minimum threshold of 4.7 logs of virus while infection was produced by a dosage of 2.3 logs. the incubation period was from four to seven days, being preceded by a viremic phase. signs were depression, ataxia and paralysis of the limbs. highest titres of virus were recovered from the brain and histopathological changes involving the ce ...	1978	667706
mitochondrial alpha-glycerophosphate dehydrogenase activity in active and torpid ground squirrels, spermophilus richardsoni.	1. mitochondrial alpha-glycerophosphate dehydrogenase (gpd) activity was assayed in liver homogenates from active and torpid ground squirrels. 2. arrhenius plots of gpd activity were linear in non-hibernating animals and discontinuous in hibernators. compared with non-hibernators, the energy of activation in hibernators was reduced between 37 and 25 degrees c, but increased between 25 and 6 degrees c. 3. a dose-response relation between gpd activity and injected thyroxine was determined in activ ...	1978	318284
thermoregulatory effects of central injection of noradrenaline in the richardson's ground squirrel (spermophilus richardsonii).		1978	33006
subcutaneous exposure of the richardson's ground squirrel (spermophilus richardsonii sabine) to western equine encephalomyelitis virus.	both adult and suckling richardson's ground squirrels (spermophilus richardsonii) were susceptible to subcutaneous exposure with western equine encephalomyelitis (wee) virus, but the virus was more virulent for sucklings than adults. in sucklings, the incubation period was from 4 to 5 days, followed by apparent signs of central nervous system (cns) involvement. death occurred 10 to 13 days postexposure. in adults, infections were inapparent or acute with typical signs of cns involvement similar ...	1976	933316
reproduction, structure and host specificity of trypanosoma (herpetosoms) tamiasi sp. n. from the eastern chipmunk, tamias striatus.	trypanosoma (herpetosoma) tamiasi sp. n. is described from blood and organs of the eastern chipmunk, tamias striatus, and the least chipmunk, eutamias minimus. in experimentally infected tamias striatus and e. minimus, trypanosoma tamiasi reproduced by equal binary fission in the trypo-, sphaero-, epi-, or amastigote form, mainly in lymphoid organs. trypomastigotes developed from amastigotes through epimastigotes, or from sphaeromastigotes, mainly in the same organs. the mean lengths of body ...	1975	1117439
natural infections of richardson's ground squirrels with western equine encephalomyelitis virus, saskatchewan, canada, 1964-1973.	a survey (1964-1973) was conducted on naturally occurring western equine encephalomyelitis (wee) virus infections of richardson's ground squirrels (rgs) in agricultural areas of saskatchewan. the survey included both serology and virus isolation attempts on live-trapped wild squirrels. throughout the study, seropostive squirrels were found in the known enzootic regions of the province each summer. the infections rate was high (11.6% of 250) in the epidemic year of 1965 and low (less than 2% o ...	1975	1148947
development of adult-young identification in richardson's ground squirrel.		1974	4421896
a telemetric study of the abdominal temperature of a hibernator, spermophilus richardsonii, maintained under constant conditions of temperature and light during the active season.		1974	4840658
climatic conditions and breeding in richardson's ground squirrel.		1973	4706255
maternal behaviour in richardson's ground squirrel (spermophilus richardsonii richardsonii): retrieval of young by non-lactating females.		1973	4735941
reproduction of richardson's ground squirrel (spermophilus richardsonii) in southern saskatchewan.		1972	4656825
chromosomes of the nevada ground squirrel spermophilus richardsonii nevadensis (howell).		1964	14233474
chromosomes and evolution of the ground squirrel, spermophilus richardsonii.		1964	14196876