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fever and survival: the role of serum iron.1. the effects of bacterial infection and temperature on serum iron levels were investigated in the lizard dipsosaurus dorsalis. 2. changes in body temperature from normal (38 degrees c) to febrile (41 degrees c) did not alter serum iron levels. injection with aeromonas hydrophila led to a significant reduction in serum iron levels, comparable to that found in mammals. this reduction in serum iron level was independent of the lizard's body temperature. 3. when grown in vitro, a. hydrophila grew ...1978678329
fever and survival.the significance of fever in response to a bacterial infection has been investigated using the lizard dipsosaurus dorsalis as an animal model. these lizards develop a fever of about 2 degrees c after injection with the bacterium aeromonas hydrophila. to determine whether this elevation in body temperature increases the resistance of the host to this infection, as measured by survival, lizards were infected with the live bacteria and placed in a neutral (38 degrees c), low (34 degrees or 36 degre ...19751114347
the energetic cost of the fever response in three species of ectothermic vertebrates.three species of ectothermic vertebrates: goldfish (carassius auratus), green tree frogs (hyla cinerea), and desert iguanas (dipsosaurus dorsalis) were used in this study. metabolic rates for each species were determined at the normal afebrile preferred body temperature and at the febrile preferred body temperature or other higher body temperatures. the febrile metabolic rate (or higher rate) was significantly greater than the afebrile metabolic rate (or lower rate) in each species. the average ...19852863044
lizard reflectivity change and its effect on light transmission through body wall.light transmission through the body wall of living, color-labile desert iguanas (dipsosaurus dorsalis) was measured by spectrophotometry. in the dark phase, the body wall's absorption of ultraviolet light and visible light was approximately twice that of the body wall in the light phase. the shorter wavelengths of ultraviolet could penetrate the body wall in the light phase but not in the dark phase. the intensity and wavelengths of light which could penetrate the body wall without pigments are ...19694883467
fever: effect of drug-induced antipyresis on survival.to determine whether the prevention of fever affects the survival of an animal infected with pathogenic bacteria, lizards (dipsosaurus dorsalis) were infected with live aeromonas hydrophila and received varying doses of sodium salicylate, an antipyretic drug. twelve lizards received identical injections of bacteria along with a nontoxic dose of sodium salicylate; five animals increased their mean body temperature at least 0.6 degrees c and survived the week, whereas seven did not develop a fever ...1976935867
plasma iron, copper, and zinc in lizard dipsosaurus dorsalis: effects of bacteria injection.the effects of inoculation of desert iguanas (dipsosaurus dorsalis) with heat-killed aeromonas hydrophila on the plasma concentrations of iron, copper, and zinc, and the total iron-binding capacity have been determined. plasma iron concentration and total iron-binding capacity fell significantly in inoculated lizards maintained at temperatures corresponding to those selected during fever. plasma copper concentration did not change in response to inoculation (as determined at 24 h postinjection). ...19817235044
histochemical, enzymatic, and contractile properties of skeletal muscle fibers in the lizard dipsosaurus dorsalis.lizard skeletal muscle fiber types were investigated in the iliofibularis (if) muscle of the desert iguana (dipsosaurus dorsalis). three fiber types were identified based on histochemical staining for myosin atpase (matpase), succinic dehydrogenase (sdh), and alphaglycerophosphate dehydrogenase (alphagpdh) activity. the pale region of the if contains exclusively fast-twitch-glycolytic (fg) fibers, which stain dark for matpase and alphagpdh, light sdh. the red region of the if contains fast-twitc ...19806456326
inhibitory effects of prolactin upon gonadotrophin-stimulated ovarian growth in the iguanid lizard, dipsosaurus dorsalis. 19705428910
fever in the lizard dipsosaurus dorsalis. 19744431469
roles of lactate and catecholamines in the energetics of brief locomotion in an ectothermic vertebrate.we have investigated the magnitude and duration of excess post-exercise oxygen consumption (epoc) in a lizard following a single bout of vigorous exercise of 5-60 s, common activity durations for many ectothermic vertebrates. desert iguanas (dipsosaurus dorsalis) were run for 5 s, 15 s, 30 s, or 60 s. oxygen consumption (vo2) increased from 0.16 ml o2 g(-1) h(-1) at rest to 1.3-1.6 ml o2 g(-1) h(-1) during 5-60 s of running. epoc duration increased with activity duration, ranging from 35-63 min. ...200111352107
metabolic support of moderate activity differs from patterns seen after extreme behavior in the desert iguana dipsosaurus dorsalis.this study examined glucose and lactate metabolism in an iguanid lizard, dipsosaurus dorsalis, during rest and after activity patterned on field behavior (15 s of running at 1 m/s). metabolite oxidation and incorporation into glycogen by the whole animal, the liver, and oxidative and glycolytic muscle fibers were measured using (14)c- and (13)c-labeled compounds. results showed that lactate metabolism is more responsive to changes that occurred between rest and recovery, whereas glucose appears ...201316555196
the energetic savings of sleep versus temperature in the desert iguana (dipsosaurus dorsalis) at three ecologically relevant temperatures.one of the proposed ecological functions of sleep is to conserve energy. the majority of studies that support this theory have been done on endothermic animals whose body temperatures drop during sleep due to the reduced neurological control of thermoregulation. in the present study, we examined typical temperatures to which the desert iguana, dipsosaurus dorsalis, is exposed to in the field and found that mean high temperatures ranged from 24-58 degrees c throughout the active portion of the ye ...200717658283
contributions to elevated metabolism during recovery: dissecting the excess postexercise oxygen consumption (epoc) in the desert iguana (dipsosaurus dorsalis).the excess postexercise oxygen consumption (epoc), a measure of recovery costs, is known to be large in ectothermic vertebrates such as the desert iguana (dipsosaurus dorsalis), especially after vigorous activity. to analyze the cause of these large recovery costs in a terrestrial ectotherm, dipsosaurus were run for 15 s at maximal-intensity (distance 35.0+/-1.9 m; 2.33+/-0.13 m s(-1)) while o(2) uptake was monitored via open-flow respirometry. muscle metabolites (adenylates, phosphocreatine, an ...200818040968
fiber-type composition in the perivertebral musculature of lizards: implications for the evolution of the diapsid trunk muscles.the perivertebral musculature of lizards is critical for the stabilization and the mobilization of the trunk during locomotion. some trunk muscles are also involved in ventilation. this dual function of trunk muscles in locomotion and ventilation leads to a biomechanical conflict in many lizards and constrains their ability to breathe while running ("axial constraint") which likely is reflected by their high anaerobic scope. furthermore, different foraging and predator-escape strategies were sho ...201323115131
phylogeography and ecological niche modeling of the desert iguana (dipsosaurus dorsalis, baird & girard 1852) in the baja california peninsula.understanding the factors that explain the patterns of genetic structure or phylogeographic breaks at an intraspecific level is key to inferring the mechanisms of population differentiation in its early stages. these topics have been well studied in the baja california region, with vicariance and the dispersal ability of individuals being the prevailing hypothesis for phylogeographic breaks. in this study, we evaluated the phylogeographic patterns in the desert iguana (dipsosaurus dorsalis), a s ...201728821185
among-individual variation in desert iguanas (squamata: dipsosaurus dorsalis): endurance capacity is positively related to home range size.among species of lizards, endurance capacity measured on a motorized treadmill is positively related to daily movement distance and time spent moving, but few studies have addressed such relationships at the level of individual variation within a sex and age category in a single population. both endurance capacity and home range size show substantial individual variation in lizards, rendering them suitable for such studies. we predicted that these traits would be positively related because endur ...201729200361
the effects of speed on the in vivo activity and length of a limb muscle during the locomotion of the iguanian lizard dipsosaurus dorsalis.the caudofemoralis muscle is the largest muscle that inserts onto the hindlimb of most ectothermic tetrapods, and previous studies hypothesize that it causes several movements that characterize the locomotion of vertebrates with a sprawling limb posture. predicting caudofemoralis function is complicated because the muscle spans multiple joints with movements that vary with speed. furthermore, depending on when any muscle is active relative to its change in length, its function can change from ac ...200111707500
intermittent locomotor activity that increases endurance also increases metabolic costs in the desert iguana (dipsosaurus dorsalis).intermittent activity, alternating bouts of activity and rest, can extend endurance relative to continuous locomotion. utilizing a rapid fatiguing activity intensity (1.08 m s(-1)), dipsosaurus dorsalis (n = 14) ran repeated bouts of varying durations (5, 15, or 30 s) interspersed with variable pause periods (100%, 200%, 400%, or 800% of the activity period) until exhausted. total distance ran increased relative to continuous locomotion. the largest increases were seen when activity periods were ...200615778936
effect of activity duration on recovery and metabolic costs in the desert iguana (dipsosaurus dorsalis).the majority of elevated o(2) consumption associated with short and vigorous activity occurs during recovery, thus an assessment of associated metabolic costs should also examine the excess post-exercise oxygen consumption (epoc). this study examined o(2) uptake during exercise, epoc and distance traveled during 5-, 15-, 60- and 300-s sprints at maximal treadmill intensity in dipsosaurus (n=10; 74.3+/-2.1 g). epoc (0.08, 0.14, 0.23 and 0.18 ml o(2) g(-1), respectively) was large (80-99% of total ...200111672684
scanning electron microscope studies of the auditory papillae of some iguanid lizards.the papillae basilares of 16 species (10 general) of iguanid lizards were studied by scanning electron microscopy. variations in the surface structures of the auditory papillae showed the following major differences: 1)papillae with localization of the unidirectional hair cells at the apical end of the papilla (anolis carolinensis); 2)papillae with absence or loss of a portion of the apical bidirectional hair-cell segment (basiliscus basiliscus); 3)papillae with a central, short ciliated, unidir ...19817304475
circadian locomotor rhythms in the desert iguana. ii. effects of electrolytic lesions to the hypothalamus.desert iguanas, dipsosaurus dorsalis, displaying freerunning circadian locomotor rhythms in conditions of constant darkness and temperature received electrolytic lesions to the hypothalamus. the locomotor activity of those lizards (n = 9) which sustained 80% or more damage to the suprachiasmatic nucleus (scn) became arrhythmic whereas all animals that sustained less than 35% damage to the scn remained rhythmic, even though they sustained significant damage to nearby regions of the hypothalamus a ...19902359055
locomotion of lizards on inclines and perches: hindlimb kinematics of an arboreal specialist and a terrestrial generalist.arboreal animals, especially lizards, often traverse three-dimensional networks of narrow perches with variable and steep inclines, but the effects of both incline and narrow surfaces on the locomotor movement and function of limbs are poorly understood. thus, we quantified the three-dimensional hindlimb kinematics of a specialized arboreal lizard, chamaeleo calyptratus, moving horizontally, and up and down a 30 degrees incline on a narrow (2.4 cm) perch and a flat surface. we compared the flat- ...200414668308
the acute phase response in the sudan plated lizard, gerrhosaurus major.the sudan plated lizard (gerrhosaurus major), previously reported to be an afebrile species, was utilized in a series of experiments to test for various aspects of the acute phase response. treatment of individuals with the antibiotic baytril resulted in a slight (0.5 degree c) but significant reduction in mean selected body temperature (msbt), while treatment with saline did not lower msbt. nonantibiotic treatment individuals had depressed plasma iron levels (86.6 +/- 22.4 micrograms fe 100 ml- ...19989773512
muscle composition and its relation to sprint running in the lizard dipsosaurus dorsalis.iguanid lizards exhibit considerable intraspecific variation in several aspects of their muscle composition. to determine the relationship of this variation to the variation in locomotor performance, running speeds of 20 male desert iguanas (dipsosaurus dorsalis) of similar mass were measured from video recordings of animals as they sprinted down a 4.9-m runway maintained at 40 degrees c, the preferred body temperature of dipsosaurus. mean sprint speed ranged from 2.2 to 4.2 m/s. selected muscle ...19883414842
retinohypothalamic projections and immunocytochemical analysis of the suprachiasmatic region of the desert iguana dipsosaurus dorsalis.two separate and distinct retinal projections to the hypothalamus in the iguanid lizard dipsosaurus dorsalis were described using horseradish peroxidase and cobalt-filling techniques. both of the projections were unilateral and completely crossed; one terminated in the supraoptic nucleus and the other in the suprachiasmatic nucleus. immunocytochemical analysis showed that the supraoptic nucleus contained cell bodies and fibers that cross-react with antibodies raised against arginine vasopressin, ...19947511057
intracellular ph in lizards after hypercapnia.we used the transmembrane distribution of 5,5-[2-14c]dimethyloxazolidine-2,4-dione ([14c]dmo) and 31p magnetic resonance spectroscopy (nmr) to investigate the effects of hypercapnia on intracellular ph (phi) in brain and skeletal muscle of two lizard species: anolis equestris and dipsosaurus dorsalis. in control animals (normocapnic), plasma pco2 (3.3 +/- 0.1 kpa) and plasma ph (7.52 +/- 0.01) for d. dorsalis were not significantly different from the values for a. equestris (2.8 +/- 0.2 kpa and ...19957733398
lizards, lipids, and dietary links to animal function.our experiments were designed to test the hypotheses that dietary lipids can affect whole-animal physiological processes in a manner concordant with changes in the fluidity of cell membranes. we measured (1) the lipid composition of five tissues, (2) body temperatures selected in a thermal gradient (t(sel)), (3) the body temperature at which the righting reflex was lost (critical thermal minimal [ctmin]), and (4) resting metabolic rate (rmr) at three body temperatures in desert iguanas (dipsosau ...200611517448
effects of thyroxine supplementation on metabolic rate and aerobic capacity in a lizard.effects of thyroxine (t4) on standard and maximal rates of o2 consumption and on citrate synthase activity, an index of mitochondrial oxidative capacity, were examined in the lizard dipsosaurus dorsalis. two weeks of daily injections of 200 ng t4/g body mass resulted in significant increases in standard (+60%) and maximal (+15%) rates of o2 consumption. citrate synthase activity in liver and in red iliofibularis and gastrocnemius muscles was significantly higher than in controls. correlational a ...19836846574
thermal dependence of passive electrical properties of lizard muscle fibres.1. the thermal dependence of passive electrical properties was determined for twitch fibres from the white region of the iliofibularis (if) muscle of anolis cristatellus (15-35 degrees c) and sceloporus occidentalis (15-40 degrees c), and for twitch fibres from the white (15-45 degrees c) and red (15-40 degrees c) regions of the if of dipsosaurus dorsalis. these species differ in thermal ecology, with anolis being the least thermophilic and dipsosaurus the most thermophilic. 2. iliofibularis fib ...19873430113
fever and antipyresis in the lizard dipsosaurus dorsalis.lizards (dipsosaurus dorsalis) were placed in a desertlike environment in which the ambient temperature (ta) at night (1800-0600 h) was 12 degrees c and the day (0600-1800 h) ta was between 30 and 55 degrees c depending on the location within the chamber. when dead aeromonas hydrophila (4 x 10(9) organisms) was injected into nine lizards, an elevation in body temperature (tb) of 2.7 degrees c was observed during the same day. on the day after bacterial injection the lizards' body temperatures av ...1976961860
endogenous pyrogen-like substance produced by reptiles.1. injection of lizards (dipsosaurus dorsalis) with rabbit endogenous pyrogen led to a fever. injections with denatured endogenous pyrogen did not affect body temperature. 2. injection of lizards with lizard endogenous pyrogen led to a fever of short duration, while injection of denatured lizard endogenous pyrogen produced no change in body temperature. 3. these data support the hypothesis that the febrile mechanism observed in the higher vertebrates has its origins in some primitive vertebrate.1977874874
the effect of oxygen and adenosine on lizard thermoregulation.a regulated decrease in internal body temperature (tb) appears to play a protective role against metabolic disruptions such as exposure to ambient hypoxia. this study examined the possibility that tb depression is initiated when low internal oxygen levels trigger the release of adenosine, a neural modulator known to influence thermoregulation. we measured selected tb of anolis sagrei in a thermal gradient under varied ambient oxygen conditions and following the administration of the adenosine re ...201312905120
ion secretion by salt glands of desert iguanas (dipsosaurus dorsalis).unlike the nacl-secreting salt glands of many birds and reptiles, the nasal salt glands of lizards can secrete potassium as well as sodium, with either chloride or bicarbonate as the accompanying anion. the factors responsible for initiating secretion by the gland and the rates of cation and anion secretion were studied in the desert iguana, dipsosaurus dorsalis. lizards were given combinations of ions for several days, and secreted salt was collected daily and analyzed for sodium, potassium, ch ...201511226011
size matters: ontogenetic variation in the three-dimensional kinematics of steady-speed locomotion in the lizard dipsosaurus dorsalis.although many studies have investigated how locomotor capacities change with size, few studies have examined whether different-sized individuals within a species have similar kinematics during locomotion. we quantified the skeletal limb morphology and the three-dimensional kinematics of the hindlimb of four sizes (4-66 g) of the lizard dipsosaurus dorsalis moving steadily at both the walk-run transition (50 % duty factor) and at a moderately fast speed of 250 cm s(-)(1). we used analyses of vari ...200010862726
activity before exercise influences recovery metabolism in the lizard dipsosaurus dorsalis.during recovery from even a brief period of exercise, metabolic rate remains elevated above resting levels for extended periods. the intensity and duration of exercise as well as body temperature and hormone levels can influence this excess post-exercise oxygen consumption (epoc). we examined the influence of activity before exercise (abe), commonly termed warm-up in endotherms, on epoc in the desert iguana dipsosaurus dorsalis. the rate of oxygen consumption and blood lactate levels were measur ...200010821738
the roles of acidosis and lactate in the behavioral hypothermia of exhausted lizards.we conducted this study to determine whether two of the physiological changes associated with non-sustainable exercise, elevated blood lactate levels and decreased arterial ph, contribute to the behavioral hypothermia exhibited by exhausted lizards. dipsosaurus dorsalis were placed in a thermal gradient and their body temperatures were recorded from 08:00 to 14:00 h. at 14:00 h, animals were subjected to different experimental regimens. in the exercise (e) regimen, animals at 40 degrees c were f ...19999882644
effects of incline and speed on the three-dimensional hindlimb kinematics of a generalized iguanian lizard (dipsosaurus dorsalis)lizards commonly move on steep inclines in nature, but no previous studies have investigated whether the kinematics of the limbs of lizards differ on inclined surfaces compared with level surfaces. therefore, we examined how the kinematics of the hindlimb were affected by both incline (downhill 30 degrees, level and uphill 30 degrees) and different speeds of steady locomotion (50-250 cm s-1) in the morphologically generalized iguanian lizard dipsosaurus dorsalis. on the uphill surface, the strid ...19999851904
effects of speed on the hindlimb kinematics of the lizard dipsosaurus dorsalislizards are the most diverse extant lineage of vertebrates believed to have retained the sprawling limb posture of ancestral tetrapods and, although the sprinting speeds of lizards are well documented, quantitative analyses of limb movements are lacking. we therefore examined a wide range of steady running speeds to quantify variation in the kinematics of a morphologically generalized hindlimb in the lizard dipsosaurus dorsalis. from speeds of 50 to 350 cm s-1, stride length, step length and str ...19989438835
the influence of corticosterone and glucagon on metabolic recovery from exhaustive exercise in the desert iguana dipsosaurus dorsalis.the skeletal muscles of ectothermic vertebrates possess an elevated glyconeogenic capacity that is responsible for a major portion of lactate removal and glycogen resynthesis following exercise. in lizards, changes in plasma hormone levels and the influence of differing hormone levels on muscle metabolism postexercise are poorly understood. we measured the effects of 5 min of exhaustive exercise on plasma levels of glucagon and corticosterone in the desert iguana dipsosaurus dorsalis. we also de ...19979169110
postexercise thermoregulatory behavior and recovery from exercise in desert iguanas.desert iguanas (dipsosaurus dorsalis) undergo respiratory recovery more rapidly and incur lower energetic costs when they recover from 40 degrees c burst activity at 20 degrees c than when they recover at 40 degrees c. however, a body temperature of 20 degrees c falls well outside the preferred activity temperature range of this species, and imposes several physiological and behavioral liabilities. to determine if exhausted animals would favor a thermal regimen that allows for rapid and inexpens ...19979035245
postbite elevation in tongue-flicking rate by an iguanian lizard,dipsosaurus dorsalis.the herbivorous iguanid lizarddipsosaurus dorsalis exhibited petf (postbite elevation in tongue-flicking rate), an increase in tongue-flicking rate after experimental removal from the mouth of food that had been bitten. this was demonstrated by a significantly higher tongue-flick rate after having bitten food than in three experimental conditions controlling for responses to the experimental setting, sight of food, and mechanical disturbance caused by the experimental removal of food from a liza ...199324248579
cytological effects of salt-stress and localization of transport adenosine triphosphatase in the lateral nasal glands of the desert iguana, dipsosaurus dorsalis. 20144278798
plasma catecholamine and corticosterone and their in vitro effects on lizard skeletal muscle lactate metabolism.lizard skeletal muscles utilize primarily lactate as a gluconeogenic substrate for glycogen replenishment following exercise. to understand the influence of selected hormones on this process, we measured changes in plasma catecholamines and corticosterone resulting from exercise in the lizard dipsosaurus dorsalis and then investigated the physiological effects of those hormones on skeletal muscle lactate and glucose metabolism in vitro. plasma epinephrine (epi), norepinephrine, and corticosteron ...19938214158
chemical and behavioral studies of femoral gland secretions in iguanid lizards.comparative studies on the chemistry and behavioral significance of femoral gland secretions in desert iguanas (dipsosaurus dorsalis) and green iguanas (iguana iguana) are reviewed. field and laboratory studies suggest that femoral gland secretions function in conspecific recognition and range marking. in desert iguanas, secretions are of low volatility and may be detected initially using long-range ultraviolet visual cues. in contrast, green iguana secretions contain a diversity of volatile lip ...19938477348
tongue-flicking and biting in response to chemical food stimuli by an iguanid lizard (dipsosaurus dorsalis) having sealed vomeronasal ducts: vomerolfaction may mediate these behavioral responses.in the iguanid lizarddipsosaurus dorsalis, chemical food stimuli were discriminated from other odorants by vomerolfaction. this was demonstrated in a 2 × 3 experiment in which groups of lizards with sealed vomeronasal ducts or sham-sealed vomeronasal ducts responded to carrot chemical stimuli, cologne, and distilled water presented on cotton-tipped applicators. abilities to detect and discriminate food chemicals were abolished in lizards having sealed vomeronasal ducts. for tongue-flick attack s ...199124258439
thyroxine secretion rates in desert lizards: dipsosaurus dorsalis and callisaurus draconoides. 19734689588
circadian locomotor rhythms in the desert iguana. i. the role of the eyes and the pineal.the pineal and the eyes are known to be important components in the circadian system of some species of lizards; their effects may be mediated by the hormone melatonin. we examined the role played by these structures in the desert iguana (dipsosaurus dorsalis). surgical removal of the pineal had no effect on circadian locomotor rhythms, even though this procedure abolished the circadian rhythm of melatonin in the blood. furthermore, when the isolated pineal of dipsosaurus was studied in organ cu ...19902359054
chemical properties of femoral gland secretions in the desert iguana,dipsosaurus dorsalis.this study investigates the chemistry of femoral gland secretions in the desert iguana,dipsosaurus dorsalis (lacertilia: iguanidae), and discusses their possible functional significance. electrophoretic and proton nmr studies indicated that the secretions are composed of approximately 80 % protein and 20% lipid material. individual differences in polyacrylamide gel banding patterns of femoral gland proteins were found. reflectance spectroscopy revealed that the secretions strongly absorb longwav ...199024264892
ontogenesis of contractile properties of skeletal muscle and sprint performance in the lizard dipsosaurus dorsalis.ontogenetic allometries of running performance in 3- to 4-m burst runs (sprints) and of the contractile properties of the fast-twitch, glycolytic region of the iliofibularis muscle (fg-if) were measured in dipsosaurus dorsalis. this iguanid lizard hatches at a body mass of about 4 g and reaches adult masses of 40-70 g. running velocity was little influenced by changes in body mass during development. stride frequency (f) declines ontogenetically and was proportional to body mass (mb) to approxim ...19883209964
reptilian skeletal muscle: contractile properties of identified, single fast-twitch and slow fibers from the lizard dipsosaurus dorsalis.contractile properties and innervation patterns were determined in identified single fibers from the iliofibularis muscle of the desert iguana, dipsosaurus dorsalis. single fibers from both the red and white regions of the iliofibularis muscle were dissected along their length under oil and a portion was mounted on transducers for determination of maximum isometric tension (po) and unloaded shortening velocity (vmax) using the slack test method. fibers were chemically skinned and activated by hi ...19872956358
lizard tail autotomy: function and energetics of postautotomy tail movement in scincella lateralis.handling of autotomized, thrashing and autotomized, exhausted tails of the lizard scincella lateralis by mammals and snakes was tested to examine the function of postautotomy tail movement. tail movement attracted a mammal's attack to the tail, permitting the lizard to escape and increased the time required for a snake to subdue a tail before swallowing it, increasing the lizard's escape time by 40 percent. lactate concentrations of autotomized tails after movement were compared to those of inta ...198317815319
intracellular ph in lizard dipsosaurus dorsalis in relation to changing body temperatures.mean whole-body and tissue-specific intracellular ph values (phi) were measured in dipsosaurus dorsalis by the dimethyloxazolidinedione technique. phi was measured in lizards at constant body temperatures (tb) (18, 25, 35, and 42 degrees c) and in lizards undergoing changes in tb between 18 and 42 degrees c. constant tb between 18 and 42 degrees c maintained for 24 h or more produced a delta ph/delta tb of -0.015 for the mean whole-body, -0.012 for venous blood, -0.0104 for cardiac muscle, and - ...19827153145
observations on the water and electrolyte composition of the iguanid lizard dipsosaurus dorsalis (baird & girard), with special reference to the control by the pituitary gland and the adrenal cortex. 19704322661
thermal reinforcement and thermoregulatory behaviour in the lizard dipsosaurus dorsalis: an operant technique. 19695370960
temperature-dependent maze learning in the desert iguana, dipsosaurus dorsalis. 19685752100
thermoregulation in the desert iguana dipsosaurus dorsalis.the body temperature of desert iguanas implanted with miniature temperature-sensitive radio transmitters was continuously monitored in their natural habitat. extensive thermoregulatory behavior occurred in retreat burrows prior to morning emergence. such behavior permits the igluana to emerge from below ground at its preferred body temperature rather than suboptimal temperature at which activity in the burrow is initiated.19675611038
neural control of gonad size by hormone feedback in the desert iguana dipsosaurus dorsalis dorsalis. 19676033859
growth response to photoperiodic stimulation in the lizard dipsosaurus dorsalis. 196514325997
effect of temperature on antibody synthesis in the reptile, dipsosaurus dorsalis. 195913675290
effects of calcitonin on electrolyte excretion in the lizard dipsosaurus dorsalis. 19827141207
thermal dependence of endurance and locomotory energetics in a lizard.the thermal dependencies of endurance and the rates of oxygen cnsumption (vo2) and carbon dioxide production (vco2) were determined for the lizard dipsosaurus dorsalis walking on a treadmill. the thermal dependencies of endurance and maximal vo2 (vo2 max) are nerly identical. the maximal sustainable speed and the speed at which vo2 max is attained at each experimental body temperature are the same. the net cost of locomotion (the slope of vo2 vs. speed) is termperature independent. resting vo2 a ...19817304779
effects of temperature on acid-base balance and ventilation in desert iguanas.the effects of constant and changing temperatures on blood acid-base status and pulmonary ventilation were studied in the eurythermal lizard dipsosaurus dorsalis. constant temperatures between 18 and 42 degrees c maintained for 24 h or more produced arterial ph changes of -0.0145 u x degrees c-1. arterial co2 tension (pco2) increased from 9.9 to 32 torr plasma [hco-3] and total co2 contents remained constant at near 19 and 22 mm, respectively. under constant temperature conditions, ventilation-g ...19816790503
regional specialization in retinal ganglion cell projection to optic tectum of dipsosaurus dorsalis (iguanidae).regional variation in the composition of the ganglion cell layer is a characteristic feature of vertebrate retinas. this suggests that corresponding patterns of regional variation might be expected in cns structures which receive a direct, topographic projection from the retina. to investigate this possibility, i studied the retinotectal projection in an iguanid lizard (dipsosaurus dorsalis), which shows a marked degree of regional variation in its retinal ganglion cell layer. results of these e ...19817217356
histochemical determination of the fiber composition of locomotory muscles in a lizard, dipsosaurus dorsalis.a histochemical survey was done on the fiber composition of 12 different locomotory muscles in the lizard dipsosaurus dorsalis. three types of fibers were found in all muscles: (1) fast-twitch-glycolytic (fg); (2) fast-twitch-oxidative-glycolytic (fog); and (3) tonic fibers. virtually all locomotory muscles contain some tonic fibers. most muscles have bulk white regions (containing mostly fg fibers) and distinct red, oxidative regions (with fog and tonic fibers). these red regions are predominan ...19806168730
electrophysiological and behavioral correlates of sleep in the desert iguana, dipsosaurus dorsalis hallowell.the circadian behavior of the desert iguana, dipsosaurus dorsalis, was investigated on the basis of behavioral observation and electrophysiological recording. d. dorsalis adequately complies with accepted criteria for both behavioral sleep and paradoxical sleep. at 20 degrees c, 12% of the photophase is spent in sleep, 95% of the scotophase is spent in sleep. paradoxical sleep occurs at all times of the year, but only at temperatures of 20 and 30 degrees c. amounts of behavioral sleep are affect ...19872881673
elevation of the panting threshold of the desert iguana, dipsosaurus dorsalis, during dehydration: potential roles of changes in plasma osmolality and body fluid volume.dehydration of the desert iguana, dipsosaurus dorsalis, resulted in a progressive elevation in the magnitude of the skin temperature necessary to elicit thermal panting (i.e., the panting threshold). panting threshold increased from 43.4 +/- 0.8 degrees c at 100% initial body weight (ibw) to 45.4 +/- 1.2 degrees c at 90% ibw to 45.7 +/- 0.9 degrees c at 80% ibw. plasma osmolality showed no significant change with dehydration to 80% ibw. changes in plasma osmolality, whether induced by nacl or no ...19863722515
day-night variations in blood and intracellular ph in a lizard, dipsosaurus dorsalis.blood ph, pco2 and po2 of dipsosaurus dorsalis were measured during the day and at night. lizards at constant body temperature (25, 37 degrees c) and lizards experiencing diurnal changes in body temperature similar to those in nature were studied. in lizards at constant body temperatures, blood ph was about 0.1 unit less and blood pco2 was 4-7 torr higher at night compared to day. similar patterns were seen in lizards on natural thermal cycles. intracellular ph (phi) of skeletal muscle, esophagu ...19863098809
thermal dependence of isotonic contractile properties of skeletal muscle and sprint performance of the lizard dipsosaurus dorsalis.contractile properties of the fast-twitch glycolytic (fg) portion of the iliofibularis muscle and sprint running performance were studied at approximately 5 degrees c intervals from 15-44 degrees c in the lizard dipsosaurus dorsalis. maximal running velocity (vr) and stride frequency (f) were both greatest when body temperature (tb) was 40 degrees c, the field-active tb in dipsosaurus. at 40 degrees c vr was 4.3 +/- 0.2 m/s and f was 13.5 +/- 0.5 s-1. between 25 and 40 degrees c, the thermal dep ...19853837028
glycogen synthesis from lactate in skeletal muscle of the lizard dipsosaurus dorsalis.the capacity of skeletal muscle to synthesize glycogen from lactate was tested in the iliofibularis muscle of the desert iguana, dipsosaurus dorsalis. like other reptiles, dipsosaurus accumulates significant lactic acid concentrations following vigorous exercise. after 5 min of progressively faster treadmill running at 35 degrees c (final speed = 2.2 km/h), blood lactate concentration increased over 14 mm, which decreased 11 mm after 2 h of recovery. blood glucose concentration remained unchange ...19853836236
reduced aerobic capacity and locomotory endurance in thyroid-deficient lizards.this study was undertaken to examine the effects of thyroid hormonal deficiency on (1) standard (smr) and maximal (vo2max) rates of o2 consumption, (2) tissue glycolytic and oxidative capacities and (3) submaximal locomotory endurance in a lizard (dipsosaurus dorsalis). surgical thyroidectomy induced hypothyroidism in all animals as determined by levels of plasma thyroxine. hypothyroid lizards had lower levels of smr (-48%), vo2max (-16%) and citrate synthase activity in liver, heart and skeleta ...19846736862
capillarization, mitochondrial densities, oxygen diffusion distances and innervation of red and white muscle of the lizard dipsosaurus dorsalis.the white and red regions of the iliofibularis muscle of the lizard dipsosaurus dorsalis were analyzed using histologic and morphometric analysis. these regions are composed of fast glycolytic (fg) and both fast oxidative, glycolytic (fog) and tonic fibers, respectively. endplate morphology and number of endplates per fiber were estimated from fibers from both areas. capillary volume densities of the red and white regions were quantified from transverse sections. mitochondrial volume of fibers f ...19846478493
postural mechanisms in the behavioral thermoregulation of a desert lizard, dipsosaurus dorsalis. 19715121913
sensitivity of parameters of estrogen action in the iguanid lizard dipsosaurus dorsalis. 19734753360
environmental influences on the testis cycles of the lizards dipsosaurus dorsalis and xantusia vigilis. 19734145713
the hypothalamic-hypophysial neurosecretory system in the iguanid lizard, dipsosaurus dorsalis: a qualitative and quantitative study. 19724649161
the role of adrenal corticosteroids in the regulation of kidney function in the desert lizard dipsosaurus dorsalis. 19724144137
studies on the control of electrolyte excretion by the nasal gland of the lizard dipsosaurus dorsalis. 19724404269
reproduction and estrogen-induced vitellogenesis in dipsosaurus dorsalis. 19724117180
regulation of skeletal muscle metabolism in the lizard dipsosaurus dorsalis by fructose-2,6-bisphosphate.changes in liver and skeletal muscle fructose-2,6-bisphosphate (fru-2,6-p2) concentrations were compared during fasting, exercise, and recovery in the lizard dipsosaurus dorsalis and in outbred mice (mus musculus). we present the first correlative evidence that suggests that a decrease in the content of fru-2,6-p2 may mediate elevated gluconeogenesis in lizard skeletal muscle. contents of fru-2,6-p2 in lizard gastrocnemius and red and white iliofibularis (if) were significantly lower (as much as ...19968945985
effects of fever on host defense mechanisms after infection in the lizard dipsosaurus dorsalis.fever has never been proven beneficial in mammals, although it enhances survival in the lizard d. dorsalis infected with aeromonas hydrophila. we examined the course of the infection and the function of host defence in febrile (41 degrees) and afebrile (35 degrees or 38 degrees) animals using this model. infected, febrile lizards had sterile blood cultures, and 1-2 logs fewer bacteria in body tissues 6-12 h after infection. granulocytes appeared early and in large numbers at the site of inoculat ...1978638032
control of panting in the desert iguana: roles for peripheral temperatures and the effect of dehydration.although it is generally held that panting is a physiological mechanism for the regulation of brain temperature during heat stress, a number of studies have pointed to the importance of peripheral input for the initiation of the panting response in a variety of animals. by presenting ambient heat loads of 47 degrees, 54 degrees, 58 degrees, and 65 degrees c, and measuring skin, ear and core temperatures of the desert iguana, dipsosaurus dorsalis, at the onset of panting, we found that the skin t ...20144056695
circadian rhythm in the secretion of corticosterone by the desert iguana, dipsosaurus dorsalis. 19725034770
acclimation to simulated altitude in the lizard dipsosaurus dorsalis. 19724404360
hormonal effects on liver glycogen and blood sugar level in the iguanid lizard dipsosaurus dorsalis. 19724338375
some cardiovascular aspects of temperature regulation in the lizard dipsosaurus dorsalis. 19714400947
periferal and central control of panting in the desert iguana, dipsosaurus dorsalis. 19715121971
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