Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| winter energy requirements of sceloporus occidentalis in the mojave desert. | 1976 | 7418 | |
| oxygen consumption of sceloporus occidentalis from three different elevations. | 1977 | 11066 | |
| role of the amygdala in the intraspecies aggressive behavior of the iguanid lizard, sceloporus occidentalis. | 1977 | 563090 | |
| endocrine control of clutch size in reptiles. vii. compensatory ovarian hypertrophy following unilateral ovariectomy in sceloporus occidentalis. | 1977 | 832816 | |
| the western fence lizard sceloporus occidentalis: evidence of field exposure to borrelia burgdorferi in relation to infestation by ixodes pacificus (acari: ixodidae). | the role of the western fence lizard sceloporus occidentalis in the enzootiology of the lyme disease spirochete borrelia burgdorferi was evaluated in the hopland and ukiah areas of mendocino county, california. in 1989, half of 74 lizards collected monthly from april to october at hopland were infested by the immature western black-legged tick ixodes pacificus at a mean intensity of 6.0 ticks per lizard. the prevalence of infestation of lizards by immature i. pacificus (36 of 73) at ukiah was si ... | 1992 | 1524146 |
| virulence of lizard malaria: the evolutionary ecology of an ancient parasite-host association. | the negative consequences of parasitic infection (virulence) were examined for two lizard malaria parasite-host associations: plasmodium agamae and p. giganteum, parasites of the rainbow lizard, agama agama, in sierra leone, west africa; and p. mexicanum in the western fence lizard, sceloporus occidentalis, in northern california. these malaria species vary greatly in their reproductive characteristics: p. agamae produces only 8 merozoites per schizont, p. giganteum yields over 100, and p. mexic ... | 1990 | 2235062 |
| survey of birds and lizards for ixodid ticks (acari) and spirochetal infection in northern california. | a total of 138 birds (24 species) was captured in an oak woodland between december 1988 and june 1989 at the university of california, sierra foothill range field station, yuba county, calif. ticks were not found on 71 birds captured between december 1988 and march 1989. five subadult ixodes pacificus cooley & kohls were removed from 3 of 67 birds caught between april and june 1989. these three birds, an orange-crowned warbler (vermivora celata (say], a lazuli bunting (passerina amoena (say], an ... | 1990 | 2280384 |
| thyroid regulation of resting metabolic rate and intermediary metabolic enzymes in a lizard (sceloporus occidentalis). | this study investigates the effects of physiological increments in plasma thyroxine (t4) at three levels of biological organization in thyroid-intact and thyroidectomized captive western fence lizards, sceloporus occidentalis. two doses of t4-loaded pellets elevated plasma t4 in thyroid-intact lizards from 4.8 +/- 0.47 to 10.7 +/- 2.25 and 20.4 +/- 5.77 ng/ml (mean +/- se). surgical thyroidectomy reduced t4 to 1.8 +/- 0.23 ng/ml, and subsequent t4 pellet implantation raised t4 to 14.8 +/- 4.30 n ... | 1990 | 2295423 |
| susceptibility of the western fence lizard (sceloporus occidentalis) to the lyme borreliosis spirochete (borrelia burgdorferi). | attempts to infect juvenile and adult western fence lizards (sceloporus occidentalis) with the lyme borreliosis spirochete (borrelia burgdorferi) were largely unsuccessful. spirochetes could not be isolated from the blood and various tissues of 14 lizards 21-32 days after they had been inoculated ip (n = 8) or sc (n = 6) with 10(6) or 10(8) b. burgdorferi representing 3 tick isolates, although 1 lizard apparently developed a transitory spirochetemia lasting 2 days. similarly, spirochetes could n ... | 1990 | 2301709 |
| lyme disease in california: interrelationship of ixodes pacificus (acari: ixodidae), the western fence lizard (sceloporus occidentalis), and borrelia burgdorferi. | the relationship of immature western black-legged ticks, ixodes pacificus cooley and kohls, to the western fence lizard, sceloporus occidentalis baird and girard, and to the lyme disease spirochete, borrelia burgdorferi, was investigated in chaparral and woodland-grass habitats in northern california from 1984 to 1986. immature ticks were found on lizards in spring and summer, but the prevalence and abundance of ticks on this host were considerably greater in spring. the peak of larval abundance ... | 1989 | 2769705 |
| the sex ratio of plasmodium gametocytes. | sex ratio theory usually predicts an equilibrium sex ratio and equal proportions of males and females in a population, including the progenitors of the reproductive cells of protozoans. this proposal was tested with three species of malarial parasites of lizards, plasmodium mexicanum of the western fence lizard, and p. agamae and p. giganteum of the african rainbow lizard, using single samples from naturally infected lizards, repeated samples from free-ranging lizards (p. mexicanum only), and re ... | 1989 | 2771445 |
| larval nematodes (ascarops sp., spirurida, spirocercidae) in liver granulomata of the western fence lizard, sceloporus occidentalis (iguanidae). | prevalence of larval nematodes (ascarops sp., spirurida, spirocercidae) and associated granulomata are reported from livers of wild populations of the western fence lizard, sceloporus occidentalis. granulomata were circumscribed by layers of fibrocytes. the encysted nematode was surrounded by masses of histiocytes, cellular debris and cells with pyknotic nuclei. | 1988 | 3411718 |
| 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 ... | 1987 | 3430113 |
| in vitro maintenance of a pure-cone retina. | the retina of the lizard, sceloporus occidentalis, appears to have only cone photoreceptors. eyecups from this animal were incubated in media containing earle's balanced salts, supplemented with amino acids and vitamins, and gassed with 5% co2/95% o2. under these conditions, good morphology, protein synthesis, and normal cyclic amp and cyclic gmp levels were maintained for 1-2 days. this in vitro preparation is likely to be useful for pharmacological studies of cone photoreceptors. | 2012 | 3516917 |
| circadian rhythms in lizards: phase response curve for melatonin. | single biweekly injections of melatonin were administered to lizards (sceloporus occidentalis) free-running (exhibiting their endogenous circadian activity rhythm) in constant dim illumination. the injections caused phase shifts in the activity rhythm whose magnitude and direction were a function of the time of the melatonin injections, relative to activity onsets. plotting the direction and amount of phase shift versus the time (phase) at which the injection was given generates a phase-response ... | 1986 | 3723331 |
| thermal dependence of contractile properties of skeletal muscle from the lizard sceloporus occidentalis with comments on methods for fitting and comparing force-velocity curves. | the isometric and isotonic contractile properties of fast-twitch glycolytic fibres of the iliofibularis muscle (fg-if) in the lizard sceloporus occidentalis were measured in vitro at 5 degrees c intervals form 10 to 40 degrees c. the mean isometric parameters at 35 degrees c, the preferred body temperature of this species, were as follows: maximum isometric force (po), 187 +/- 8 (s.e.m.) knm-2; ratio of twitch force to tetanic force (ptw/po), 0.46 +/- 0.02; time to peak twitch tension (tptw), 7. ... | 1986 | 3806003 |
| thermal dependence of sprint performance of the lizard sceloporus occidentalis. | sprint velocity of the lizard sceloporus occidentalis was maximal at preferred body temperature (tb, 35 degrees c). mean running velocity (vr) and stride frequency (f) at this temperature were 3.23 +/- 0.7 (mean +/- s.e.m.) ms-1 and 15.6 +/- 0.3 s-1, respectively. vr and f did not change significantly when tb was raised to 40 degrees c. at tb values between 25 and 35 degrees c the thermal dependencies of vr (q10 = 1.23) and f (q10 = 1.12) were quite low. at tb values below 25 degrees c the therm ... | 1986 | 3806004 |
| extraretinal photoreception in the lizard sceloporus occidentalis: phase response curve. | all submammalian vertebrates have extraretinal photoreceptors (err) that can mediate entrainment of circadian rhythms to 24-h light-dark (ld) cycles. phase response curves (prc) for 6-h fluorescent light pulses were generated for lizards (sceloporus occidentalis) previously subjected to sectioning of both optic nerves (onx). the prc for onx lizards (only errs present) shows a threefold increase in the amplitude of both the advance and delay portions of the prc compared with a prc previously gene ... | 1985 | 3985182 |
| entrainment of the circadian activity rhythm of a lizard to melatonin injections. | the circadian activity rhythms of lizards (sceloporus occidentalis) can be entrained (synchronized) to a period of 24 hr by melatonin injections given every other day at the same time of day, but not by saline injections. the activity onsets of the entrained lizards exhibited two preferred phase-relationships (approximately 165 degrees and approximately 30 degrees) with the time of melatonin injections with the 30 degree phase only rarely observed. these results suggest that endogenous rhythms o ... | 2014 | 4070395 |
| the effects of altitude on oxygen-binding parameters of the blood of the iguanid lizards, sceloporus jarrovi and sceloporus occidentalis. | 1972 | 4145242 | |
| effects of temperature on brain contents of 5-hydroxytryptamine and related indoles in a lizard, sceloporus occidentalis. | 1965 | 5295193 | |
| chromosome morphology of sceloporine lizards (sceloporus occidentalis and s. graciosus). | 1970 | 5413798 | |
| the occurrence and development of plasmodium mexicanum in the western fence lizard sceloporus occidentalis. | 1970 | 5420333 | |
| hormonal control in pigmentary sexual dimorphism in sceloporus occidentalis. | 1971 | 5550935 | |
| factors in the measurement of pineal acetylserotonin methyltransferase activity in the lizard sceloporus occidentalis. | 1971 | 5559133 | |
| the effect of vitamin a deficiency on photoreceptors in the lizard sceloporus occidentalis. | 1964 | 5896517 | |
| cyclic nucleotides of cone-dominant retinas. reduction of cyclic amp levels by light and by cone degeneration. | dark-adapted retinas or whole eyes of 13-line ground squirrels (citellus tridecemlineatus) and western fence lizards (sceloporus occidentalis) contain higher levels of cyclic amp than of cyclic gmp. in these cone-dominant retinas, light reduces cyclic amp content selectively. freezing of dark- or light-adapted retinas or eyes also reduces cyclic amp content, with only minimal changes in cyclic gmp levels. in addition, exposure of frozen retinas of dark-adapted ground squirrel to light results in ... | 1981 | 6256308 |
| the influence of light on cone disk shedding in the lizard, sceloporus occidentalis. | the lizard, sceloporus occidentalis has an all-cone retina. in lizards maintained on a 12-h light:12-h dark (12l:12d) cycle, a burst of cone outer segment (cos) shedding occurs 2 h after light offset (1400 h circadian time) (young, r.w., 1977, j. ultrastruct. res. 61:172-72). in this investigation, we studied the effect of different lighting regimes on the pattern of cone disk shedding in this species. when lizards entrained to a 12l:12d cycle are kept in constant darkness (dd), the shedding pea ... | 1984 | 6746734 |
| circadian pacemakers in lizards: phase-response curves and effects of pinealectomy. | phase-response curves (prcs) for 6-h fluorescent light pulses are described for both intact (sham-pinealectomized) and pinealectomized iguanid lizards (sceloporus occidentalis). although strongly diurnal in habit the prc for intact lizards is more typical of those seen in nocturnal rodents. other "nocturnal" characteristics of this lizard include the fact that the average free-running period (tau) is less than 24 h and the average tau in continuous light is longer than that observed in continuou ... | 1983 | 6859292 |
| species typical display behavior following stimulation of the reptilian striatum. | seventy unanesthetized, unrestrained western fence lizards (sceloporus occidentalis) were electrically stimulated through implanted electrodes. behavior elicited included the species typical assertion display, elements of the challenge display and elementary locomotor responses: circling, rolling and curling. the assertion and challenge displays were elicited from telencephalic sites whereas the elementary locomotor effects were elicited from electrodes in the brain stem. assertion displays were ... | 1982 | 6891077 |
| lizards infected with malaria: physiological and behavioral consequences. | in northern california, western fence lizards, sceloporus occidentalis, are frequently parasitized by plasmodium mexicanum, which causes malaria. animals with this naturally occurring malarial infection are anemic: immature erythrocytes in peripheral blood become abundant (1 to 30 percent), and blood hemoglobin concentration decreases 25 percent. maximal oxygen consumption decreases 15 percent and aerobic scope drops 29 percent in infected lizards; both correlate with blood hemoglobin concentrat ... | 1982 | 7112113 |
| 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 ... | 1981 | 7304475 |
| western fence lizard (sceloporus occidentalis) chemical signals. ii. a replication with naturally breeding adults and a test of the cowles and phelan hypothesis of rattlesnake olfaction. | the capacity of naturally breeding western fence lizards (sceloporus occidentalis biseriatus) to discriminate and respond to conspecific and control chemical cues was examined. lizards were presented with markings and exudates of male and female donors, as well as cologne (a pungency control) and water, in a successive discrimination procedure. behavioral actions quantified after exposure to the different chemical cue types included lingual extrusions (tongue flicks and substrate licks), rapid n ... | 1981 | 7338721 |
| diel activity of nymphal dermacentor occidentalis and ixodes pacificus (acari: ixodidae) in relation to meteorological factors and host activity periods. | relation of diel activity and questing behavior of nymphal dermacentor occidentalis marx and ixodes pacificus cooley & kohls to meteorological factors was investigated in a shaded versus a sun-exposed outdoor arena. oak-woodland soil covered partially with leaf litter and small rocks, and 24 vertically oriented grass stems 2.5, 5.0, 10.0, and 20.0 cm tall were provided as substrate and potential questing sites. tick activity and weather conditions were monitored bihourly during 15 diel (24-h) ex ... | 1995 | 7616519 |
| external and internal influences on indices of physiological stress: ii. seasonal and size-related variations in blood composition in free-living lizards, sceloporus occidentalis. | seasonal changes in blood composition (plasma osmolality, total plasma protein, hematocrit) in two free-living populations of fence lizards, sceloporus occidentalis, one living in a very arid environment (pearblossom, ca) and another in a milder desert (bend, or), were analyzed. in this analysis, two features of reptilian physiology and ecology were incorporated: ontogenetic variation in blood composition and seasonal variation in body-size distribution. the population living in the arid environ ... | 1995 | 7622998 |
| external and internal influences on indices of physiological stress. i. seasonal and population variation in adrenocortical secretion of free-living lizards, sceloporus occidentalis. | the plasma levels of glucocorticoid hormones (e.g., corticosterone and cortisol) are often used as an index of physiological stress. however, under natural conditions, glucocorticoid secretion can respond to both environmental influences (e.g., extreme climatic conditions) and internal influences (populational differences and annual seasonal cycles). to distinguish between these kinds of influences, we examined seasonal variation in basal levels of corticosterone and the adrenocortical response ... | 1995 | 7852947 |
| daily melatonin infusions entrain the locomotor activity of pinealectomized lizards. | previously, it was shown that the locomotor activity rhythms of pineal-intact lizards (sceloporus occidentalis) could be entrained to a periodicity of 24 h by 10-micrograms melatonin injections administered every other day at the same time. the present study examined the response of the circadian activity rhythm of pinealectomized s. occidentalis to daily 12-h infusions of smaller quantities of melatonin (0.1 or 5 micrograms melatonin/day). the results show that entrainment is achieved by infusi ... | 1995 | 8577892 |
| interleukin-1 beta reduces daily activity level in male lizards, sceloporus occidentalis. | in mammals, interleukin-1 (il-1) mediates many of the behavioral consequences of pathogen infection. other vertebrates show behavioral changes when infected, but the neuroendocrine bases of these changes are seldom known. here we report that il-1 beta alters the daily activity cycle of lizards (sceloporus occidentalis) similar to that seen in lizards infected with malaria. to our knowledge, this is the first report of behavioral effects of interleukin in lower vertebrates. male lizards were inje ... | 1996 | 8735570 |
| borreliacidal factor in the blood of the western fence lizard (sceloporus occidentalis). | in some populations of the western black-legged tick, ixodes pacificus, the prevalence of infection with lyme disease spirochetes (borrelia burgdorferi) in nymphal ticks exceeds those in adult ticks by 3-4-fold. experiments were conducted to determine if the reduced spirochetal prevalence in adult ticks is due to the presence of anti-borrelial antibodies or to another borreliacidal factor in the blood of the western fence lizard, sceloporus occidentalis, a primary host of subadult i. pacificus, ... | 1998 | 9488334 |
| abundance of ticks (acari: ixodidae) infesting the western fence lizard, sceloporus occidentalis, in relation to environmental factors. | we examined the impact of environmental characteristics, such as habitat type, topographic exposure and presence of leaf litter, on the abundance of ixodes pacificus ticks infesting the western fence lizard (sceloporus occidentalis) at the university of california hopland research and extension center (hrec), mendocino county, california. a total of 383 adult lizards were slip-noosed and examined for tick infestation in april and may 1998. at least 94% of the lizards were infested by ticks and a ... | 1999 | 10581712 |
| oxygen consumption by mitochondria from an endotherm and an ectotherm. | comparisons of metabolic properties of mitochondria from an endothermic and an ectothermic vertebrate were performed. oxygen (o2) consumption rates of liver mitochondria from laboratory mice and western fence lizard (sceloporus occidentalis) were determined over a range of temperatures (10, 20, 30 and 37 degrees c) and in the presence of a variety of substrates. at 37 degrees c the o2 consumption rate of mouse mitochondria was 4-11 times higher than lizard mitochondria in the presence of five of ... | 1999 | 10582317 |
| life history of a malaria parasite (plasmodium mexicanum) in its host, the western fence lizard (sceloporus occidentalis): host testosterone as a source of seasonal and among-host variation? | the course of infection of a malaria parasite (plasmodium mexicanum) is highly variable in its host, the fence lizard (sceloporus occidentalis). however, a seasonal trend is superimposed on this variation such that gametocyte production is intensified during mid- to late summer. host testosterone levels follow a similar seasonal fluctuation and are variable among individual lizards. we sought to determine if testosterone levels affect seasonal and among-host variation in 11 p. mexicanum life his ... | 2000 | 11128477 |
| a comparative study of mammalian and reptilian alternative pathway of complement-mediated killing of the lyme disease spirochete (borrelia burgdorferi). | the potential bactericidal activity of the alternative complement pathway of mammalian and reptilian sera to borrelia burgdorferi sensu stricto (s.s.) was evaluated in vitro. complement-mediated killing was observed when cultured spirochetes were inoculated into sera from the western fence lizard (sceloporus occidentalis) and from the southern alligator lizard (elgaria multicarinata), but not when they were inoculated into serum from either the deer mouse (peromyscus maniculatus) or from humans. ... | 2000 | 11191895 |
| landscape features associated with infection by a malaria parasite (plasmodium mexicanum) and the importance of multiple scale studies. | in a 3-year study, we examined landscape features (aspect, slope, sun exposure, canopy cover, type of ground cover, and nearest water source) that were potentially related to prevalence of infection with plasmodium mexicanum in fence lizards (sceloporus occidentalis) within a 4.5 ha study area in northern california, usa. logistic regression analysis showed that ground cover type was the primary mediator of the probability of p. mexicanum infection. infected lizards were captured more often in r ... | 2001 | 11393823 |
| birds and their ticks in northwestern california: minimal contribution to borrelia burgdorferi enzootiology. | birds and their attendant ticks were surveyed for infection with the lyme disease spirochete borrelia burgdorferi, in chaparral and woodland-grass habitats in northwestern california from march to july, 1998 to 1999. in total, 234 birds were captured and recaptured (15%); nearly 2.5 times more birds were captured in chaparral than in woodland-grass. overall, 34 species representing 15 families were collected during this study; of these, 24 species were caught in chaparral, 19 in woodland-grass, ... | 2001 | 11534638 |
| prevalence and abundance of ixodes pacificus immatures (acari: ixodidae) infesting western fence lizards (sceloporus occidentalis) in northern california: temporal trends and environmental correlates. | the prevalence and abundance of immature ixodes pacificus ticks on western fence lizards (sceloporus occidentalis) were examined in relation to time of year, host attributes (i.e., age, gender, and presence or absence of blood parasites), and 5 environmental characteristics, including topographic exposure and ground cover substrate, over a 2-year period in northern california. lizards were infested with subadult ticks from early march until late july or early august, with peak median numbers of ... | 2001 | 11780813 |
| nymphs of the western black-legged tick (ixodes pacificus) collected from tree trunks in woodland-grass habitat. | nymphs of the western black-legged tick, ixodes pacificus, were found on the trunks of trees during spring and summer in northwestern california. in a woodland-grass habitat, large- and medium-sized (> 130 cm and 80-130 cm in circumference, respectively), moss-covered oak (quercus spp.) trees supported ticks significantly more often than trees without these characteristics. additionally, trees with basal leaf-litter and lacking shade (at time of sampling) were significantly associated with the p ... | 2001 | 11813653 |
| evaluation of western fence lizards (sceloporus occidentalis) and eastern fence lizards (sceloporus undulatus) as laboratory reptile models for toxicological investigations. | a need is recognized for one or more laboratory reptile models for use in ecotoxicological studies and risk assessments. maintenance of breeding populations of most reptile species under laboratory conditions is not practical because of their size and slow maturation rate. however, a number of species of spiny lizards (sceloporus sp.) are small, mature quickly, and reproduce under laboratory conditions. we evaluated three populations of western fence lizards (s. occidentalis) and four population ... | 2002 | 12013135 |
| gametocyte sex ratio of a malaria parasite: experimental test of heritability. | the gametocyte sex ratio of plasmodium mexicanum, a malaria parasite of western fence lizards, was studied in a modified garden experiment. each of 6 naturally infected lizards was used to initiate 20 replicate-infections in naive western fence lizards. a significant donor effect was observed for the sex ratios of recipient infections at their maximal parasitemia, and this effect was associated with the sex ratio of the donor infection. in 20 infections in which sex ratio was followed during the ... | 2002 | 12099417 |
| dose-response and time course relationships for vitellogenin induction in male western fence lizards (sceloporus occidentalis) exposed to ethinylestradiol. | the long-term goal of this research is to develop and validate an in vivo reptile model for endocrine-mediated toxicity using fence lizards (sceloporus spp.). one of the best defined estrogenic responses in oviparous vertebrates is induction of the yolk precursor protein, vitellogenin (vtg). in this study, dose-response and time course relationships for vtg induction were determined in male western fence lizards (sceloporus occidentalis) given intraperitoneal injections of 17alpha-ethinylestradi ... | 2002 | 12109741 |
| relative importance of lizards and mammals as hosts for ixodid ticks in northern california. | abstract lizards and mammals were trapped and examined for ticks from august 1992 to june 1993 in two habitat types, chaparral and woodland-grass, in northern california. five tick species were collected from mammals (dermacentor occidentalis, haemaphysalis leporispalustris, ixodes pacificus, i. spinipalpis, i. woodi), but only i. pacificus was found on lizards. dermacentor occidentalis, i. pacificus, and i. woodi occurred in both habitats, whereas h. leporispalustris and i. spinipalpis were fou ... | 2002 | 12475082 |
| manipulation of the vertebrate host's testosterone does not affect gametocyte sex ratio of a malaria parasite. | gametocyte sex ratio of the malaria parasite plasmodium mexicanum is variable in its host, the western fence lizard (sceloporus occidentalis), both among infections and within infections over time. we sought to determine the effect of host physiological quality on the gametocyte sex ratio in experimentally induced infections of p. mexicanum. adult male lizards were assigned to 4 treatment groups: castrated, castrated + testosterone implant, sham implant, and unmanipulated control. no significant ... | 2003 | 12659329 |
| hot rocks or no hot rocks: overnight retreat availability and selection by a diurnal lizard. | i used radio telemetry to determine the effects of substrate size and composition on overnight retreat site selection by western fence lizards (sceloporus occidentalis). in watersheds of northern california (usa), these lizards occupy two habitat types differing in substrate characteristics: rocky cobble bars found in the dry, active channels of rivers and grassy upland meadows. rocky substrates, found almost exclusively on cobble bars, provided warmer potential retreat sites than all available ... | 2003 | 12802672 |
| effects of 17alpha-ethinylestradiol on immune parameters in the lizard sceloporus occidentalis. | we examined the effect of 17alpha-ethinylestradiol on immunity of the western fence lizard, sceloporus occidentalis. injection of 17alpha-ethinylestradiol resulted in dose-dependent suppression of peripheral blood leukocyte levels as determined by cell counts, whereas total spleen cell levels were decreased only at higher doses of 17alpha-ethinylestradiol. in contrast, spleen cell proliferation was enhanced by 17alpha-ethinylestradiol as measured by reduction of mtt to formazan following a two-w ... | 2003 | 12900939 |
| the gross and microscopic anatomy of the liver and gall bladder of the lizard, sceloporus occidentalis biseriatus (hallowell). | 1954 | 13189140 | |
| effects of parietalectomy and sustained temperature on thyroid of lizard, sceloporus occidentalis. | 1959 | 13658226 | |
| further observations on the fine structure of the parietal eye of lizards. | an electron microscopical study of the third eye of the western fence lizard, sceloporus occidentalis, fixed with 1 per cent osmium tetroxide, ph 7.4-7.6, for 16 to 20 hours at 0 degrees c., revealed the following new facts. the fibrillar system of the retinal photoreceptor consists of nine double fibrils enclosed in a sheath. pigment cells and lens cells possess similar systems. two short cylindrical centrioles are associated with the fibrillar apparatus: one, from which striated rootlets exten ... | 1960 | 13725484 |
| parietal eye nerve in the fence lizard. | a nerve from the parietal eye of the western fence lizard, sceloporus occidentalis, is described as leaving inconspicuously from the third-eye and extending caudally under the dura mater and then ventrally along the left anterolateral surface of the epiphysis to the habenular commissure of the brain. the existence of a parietal nerve must be considered in interpreting the effects of parietalectomy. | 1959 | 13819089 |
| the western black-legged tick, ixodes pacificus, in the sutter buttes. | the western black-legged tick, ixodes pacificus, was collected from huff canyon in the sutter buttes in north central california, sutter county. the sutter buttes are within the sacramento valley and outside the normal distribution of i. pacificus in california. adult i. pacificus were collected via flagging as they quested along deer trails; subadult life stages were collected from three species of lizard, elgaria multicarinata, sceloporus occidentalis, and s. graciosus. adult ticks were tested ... | 2003 | 14714665 |
| bacteriolytic activity of selected vertebrate sera for borrelia burgdorferi sensu stricto and borrelia bissettii. | an in vitro assay to evaluate the bacteriolytic activity of the complement pathway was applied to 2 strains of borrelia bissettii, co501 and dn127, and compared with that of b. burgdorferi sensu stricto b31. sera from mule deer (odocoileus hemionus) and the western fence lizard (sceloporus occidentalis) were completely borreliacidal for b. burgdorferi and for both strains of b. bissettii. serum from bobwhite quail (colinus virginianus) was nonlytic for b. burgdorferi and partially lytic for b. b ... | 2003 | 14740924 |
| gametocyte sex ratio of a malaria parasite: response to experimental manipulation of parasite clonal diversity. | sex ratio theory posits that the adaptive proportion of male to female gametocytes of a malaria parasite within the vertebrate host depends on the degree of inbreeding within the vector. gametocyte sex ratio could be phenotypically flexible, being altered based on the infection's clonal diversity, and thus likely inbreeding. this idea was tested by manipulating the clonal diversity of infections of plasmodium mexicanum in its lizard host, sceloporus occidentalis. naive lizards were inoculated wi ... | 2004 | 15002900 |
| life-history studies on two molecular strains of mesocestoides (cestoda: mesocestoididae): identification of sylvatic hosts and infectivity of immature life stages. | life-cycle studies were conducted on 2 molecular strains of mesocestoides tapeworms that represent different evolutionary lineages (clades a and b). wild carnivores, reptiles, and rodents were examined for tapeworm infections at 2 enzootic sites: (1) san miguel island (smi), a small island off the coast of southern california and (2) hopland research and extension center (hrec), a field station in northern california. results indicate that deer mice (peromyscus maniculatus) and coyotes (canis la ... | 2004 | 15040675 |
| habitat-related variation in infestation of lizards and rodents with ixodes ticks in dense woodlands in mendocino county, california. | during the spring and early summer of 2002, we examined the relative importance of borrelia-refractory lizards (sceloporus occidentalis, elgaria spp.) versus potential borrelia burgdorferi sensu lato (s.l.)-reservoirs (rodents) as hosts for ixodes pacificus immatures in 14 woodland areas (six oak, five mixed oak/douglas fir, and three redwood/tanoak areas) distributed throughout mendocino county, california. lizards were estimated to serve as hosts for 93-98% of all larvae and > or =99.6% of all ... | 2004 | 15347025 |
| mitochondrial dna sequences of five squamates: phylogenetic affiliation of snakes. | complete or nearly complete mitochondrial dna sequences were determined from four lizards (western fence lizard, warren's spinytail lizard, terrestrial arboreal alligator lizard, and chinese crocodile lizard) and a snake (texas blind snake). these genomes had a typical gene organization found in those of most mammals and fishes, except for a translocation of the glutamine trna gene in the blind snake and a tandem duplication of the threonine and proline trna genes in the spinytail lizard. althou ... | 2004 | 15449546 |
| respiratory and behavioral effects of ozone on a lizard and a frog. | ozone at concentrations found in urban air pollution is known to have significant physiological effects on humans and other mammals. exposure of the lizard, sceloporus occidentalis, to 0.6 ppm ozone for 4 h at 25 degrees c induced 1.6 degrees c of behavioral hypothermia immediately following exposure, but selected body temperature recovered to control 35.3 degrees c the next day. lizards exposed at 35 degrees c to 0.6 ppm ozone for 4 h selected body temperatures 1.9 degrees c below controls afte ... | 2004 | 15556394 |
| transfer of selenium from prey to predators in a simulated terrestrial food chain. | little is known about the accumulation and effects of selenium in reptiles. we developed a simplified laboratory food chain where we fed commercial feed laden with seleno-d,l-methionine (30 microg/g dry mass) to crickets (acheta domestica) for 5-7 d. se-enriched crickets (approximately 15 microg/g se [dry mass]) were fed to juvenile male and female lizards (sceloporus occidentalis) for 98 d while conspecifics were fed uncontaminated crickets. lizards fed contaminated prey accumulated se concentr ... | 2005 | 15620590 |
| the roles of birds, lizards, and rodents as hosts for the western black-legged tick ixodes pacificus. | we compared the infestation by ixodid ticks of lizards, rodents, and birds collected simultaneously within areas representing common habitat types in mendocino county, ca. lizards were infested only by ixodes pacificus cooley and kohls, birds by i. pacificus and haemaphysalis leporispalustris (packard), and rodents by i. pacificus, i. spinipalpis hadwen and nuttall, i. woodi bishopp, dermacentor occidentalis marx, and d. variabilis (say). infestation by i. pacificus larvae and nymphs of lizards ... | 2004 | 15709249 |
| effect of acute exposure to malathion and lead on sprint performance of the western fence lizard (sceloporus occidentalis). | there are few ecotoxicological studies involving reptiles, despite the fact that anthropogenic pollutants have been identified as a major threat to reptile populations worldwide. particularly lacking are effects-based studies in reptiles exposed to known concentrations of contaminants. we hypothesized that acute exposure to neurotoxic metals and pesticides could influence locomotor performance of reptiles. to test this hypothesis, we exposed western fence lizards (sceloporus occidentalis) to two ... | 2006 | 16465557 |
| isolation and partial characterization of proteins involved in maternal transfer of selenium in the western fence lizard (sceloporus occidentalis). | selenium from dietary exposure is efficiently transferred from mother to offspring in oviparous vertebrates, where it can cause severe teratogenic effects. we isolated and partially characterized proteins involved in maternal transfer of selenium in the oviparous lizard sceloporus occidentalis using size-exclusion chromatography, inductively coupled plasma-mass spectrometry, and polyacrylamide gel electrophoresis. selenium from dietary selenomethionine exposure was incorporated into at least thr ... | 2006 | 16833149 |
| refractoriness of the western fence lizard (sceloporus occidentalis) to the lyme disease group spirochete borrelia bissettii. | the western fence lizard, sceloporus occidentalis, is refractory to experimental infection with borrelia burgdorferi sensu stricto, one of several lyme disease spirochetes pathogenic for humans. another member of the lyme disease spirochete complex, borrelia bissettii, is distributed widely throughout north america and a similar, if not identical, spirochete has been implicated as a human pathogen in southern europe. to determine the susceptibility of s. occidentalis to b. bissettii, 6 naïve liz ... | 2006 | 16995383 |
| impaired terrestrial and arboreal locomotor performance in the western fence lizard (sceloporus occidentalis) after exposure to an ache-inhibiting pesticide. | we examined the effects of a commonly used ache-inhibiting pesticide on terrestrial and arboreal sprint performance, important traits for predator avoidance and prey capture, in the western fence lizard (sceloporus occidentalis). lizards were exposed to carbaryl (2.5, 25, and 250 microg/g) and were raced before and 4, 24, and 96 h after dosing. in the terrestrial setting, exposure to low concentrations of carbaryl had stimulatory effects on performance, but exposure to the highest concentration ... | 2007 | 17360091 |
| energy acquisition and allocation in an ectothermic predator exposed to a common environmental stressor. | stressors are commonly encountered by organisms and often prove to be energetically costly. certain stressors can simultaneously affect multiple components of an animal's energy budget and can either exacerbate energetic costs to the individual or offset one another. here we used a commonly encountered stressor, the pesticide carbaryl, to examine the complex effects that acute environmental disturbances can have on energy expenditure, allocation, and acquisition, important processes that influen ... | 2007 | 17374566 |
| ability of transstadially infected ixodes pacificus (acari: ixodidae) to transmit west nile virus to song sparrows or western fence lizards. | the hypothesis that ixodes pacificus cooley & kohls (acari: ixodidae) may serve as a reservoir and vector of west nile virus (family flaviviridae, genus flavivirus, wnv) in california was tested by determining the ability of this tick species to become infected with the ny99 strain of wnv while feeding on viremic song sparrows, to maintain the infection transstadially, and then to transmit wnv to recipient naive song sparrows and western fence lizards during the nymphal stage. the percentage of ... | 2007 | 17427704 |
| assessment of lead uptake in reptilian prey species. | as part of an investigation determining the trophically available fraction of metals in a model terrestrial food web, i.e., invertebrate prey to western fence lizards (sceloporus occidentalis), we evaluated the ability of several invertebrate prey to bioaccumulate lead and to form metals-rich granules, which are hypothesized to be non-available to predators. crickets (acheta domestica), tenebroid beetle larvae (tenebrio molitor), and isopods (porcellio scaber) were selected as model prey organis ... | 2007 | 17490716 |
| experimental test for premunition in a lizard malaria parasite (plasmodium mexicanum). | premunition in plasmodium spp. is the prevention of superinfection by novel genotypes entering an already established infection in a vertebrate host. evidence for premunition was sought for the lizard malaria parasite, p. mexicanum, in its natural host, the fence lizard, sceloporus occidentalis. clonal diversity (= alleles for the haploid parasite) was determined with the use of 3 microsatellite markers. both naturally infected lizards (n = 25) and previously noninfected lizards (n = 78) were in ... | 2007 | 17539410 |
| selenomethionine biotransformation and incorporation into proteins along a simulated terrestrial food chain. | selenium is an essential trace element in vertebrates, but there is a narrow concentration range between dietary requirement and toxicity threshold. although a great deal is known about the biochemistry of se from a nutritional perspective, considerably less attention has been focused on the specific biochemistry of se as an environmental toxicant. recent advances in hyphenated analytical techniques have provided the capability of quantifying specific chemical forms of se in biological tissues a ... | 2007 | 17547184 |
| clonal diversity of a lizard malaria parasite, plasmodium mexicanum, in its vertebrate host, the western fence lizard: role of variation in transmission intensity over time and space. | within the vertebrate host, infections of a malaria parasite (plasmodium) could include a single genotype of cells (single-clone infections) or two to several genotypes (multiclone infections). clonal diversity of infection plays an important role in the biology of the parasite, including its life history, virulence, and transmission. we determined the clonal diversity of plasmodium mexicanum, a lizard malaria parasite at a study region in northern california, using variable microsatellite marke ... | 2007 | 17594442 |
| effects of repeated exposure to malathion on growth, food consumption, and locomotor performance of the western fence lizard (sceloporus occidentalis). | effects of repeated pollutant exposure on growth, locomotor performance, and behavior have rarely been evaluated in reptiles. we administered three doses of malathion (2.0, 20, or 100mg/kg body weight) to western fence lizards (sceloporus occidentalis) over an 81day period. eight and 23% mortality occurred at 20 and 100mg/kg (p=0.079) and 85% of lizards in the 100mg/kg group exhibited clinical symptoms of poisoning. growth, food consumption, body condition index, and terrestrial locomotor perfor ... | 2008 | 17611009 |
| allometric engineering: an experimental test of the causes of interpopulational differences in performance. | hatchling lizards (sceloporus occidentalis) from a southern population are large and have high locomotor performance (speed and stamina) relative to hatchlings from northern populations. in order to determine whether differences in performance are an allometric consequence of interpopulation differences in size, yolk was removed from southern eggs, thereby producing miniaturized hatchlings equivalent in size to northern hatchlings. miniaturized southern hatchlings no longer had higher speed than ... | 1990 | 17733374 |
| sceloporus occidentalis: preferred body temperature of the western fence lizard. | given equal thermal opportunities during four seasonal test periods, western fence lizards active above ground preferred constant body temperature throughout the year. lizards recovered from subsurface retreats in the fall exhibited a mean body temperature significantly lower than that for sequestered lizards recorded during winter, spring, and summer. | 1966 | 17754818 |
| effect of acclimation on the preferred body temperature of the lizard, sceloporus occidentalis. | the preferred body temperature was determined for several groups of sceloporus occidentalis previously acclimated to several constant temperature levels. acclimation to a high temperature (35 degrees c) resulted in the selection of a lowered mean preferred body temperature, whereas acclimation to lower temperatures (12 degrees c and 25 degrees c) produced no change in the preferred body temperature. | 1960 | 17775548 |
| effect of exogenous corticosterone on respiration in a reptile. | release of glucocorticoids (gcs) enables organisms to meet energy requirements during stressful situations by regulating intermediary metabolism. in the absence of compensatory mechanisms, increased metabolic activity (e.g., protein catabolism, lipolysis, and gluconeogenesis) should translate to increases in whole animal metabolism, and therefore energy expenditures, by organisms. however, to our knowledge, no study has estimated the total energy cost of elevated plasma gcs in any organism. here ... | 2008 | 18249406 |
| dose-related effects following oral exposure of 2,4-dinitrotoluene on the western fence lizard, sceloporus occidentalis. | 2,4-dintitrotoluene (2,4-dnt) is an explosive frequently found in the soil of military installations. because reptiles can be common on these sites, ecological risk assessments for compounds such as 2,4-dnt could be improved with toxicity data specific to reptiles. western fence lizards, sceloporus occidentalis, were used to develop a laboratory toxicity model for reptiles. a hierarchical approach was used; acute to subchronic studies were conducted to provide toxicity data relevant to short- an ... | 2008 | 18348623 |
| estimating maximum performance: effects of intraindividual variation. | researchers often estimate the performance capabilities of animals using a small number of trials per individual. this procedure inevitably underestimates maximum performance, but few studies have examined the magnitude of this effect. in this study we explored the effects of intraindividual variation and individual sample size on the estimation of locomotor performance parameters. we measured sprint speed of the lizard sceloporus occidentalis at two temperatures (20 degrees c and 35 degrees c), ... | 2008 | 18375858 |
| toxicity of oral exposure to 2,4,6-trinitrotoluene in the western fence lizard (sceloporus occidentalis). | contamination of the soil with the explosive 2,4,6-trinitrotoluene (tnt) has been found at military sites, many of which are habitats used by reptiles. to provide data useful in assessing ecological risk for reptilian species, acute, subacute, and subchronic oral toxicity studies were conducted with the western fence lizard (sceloporus occidentalis). oral median lethal dose (ld50) values for tnt in corn oil were 1,038 and 1,579 mg/kg of body weight for male and female lizards, respectively. over ... | 2008 | 18419183 |
| clonal diversity within infections and the virulence of a malaria parasite, plasmodium mexicanum. | both verbal and mathematical models of parasite virulence predict that genetic diversity of microparasite infections will influence the level of costs suffered by the host. we tested this idea by manipulating the number of co-existing clones of plasmodium mexicanum in its natural vertebrate host, the fence lizard sceloporus occidentalis. we established replicate infections of p. mexicanum made up of 1, 2, 3, or >3 clones (scored using 3 microsatellite loci) to observe the influence of clone numb ... | 2008 | 18937882 |
| toxic effects of oral hexahydro-1,3,5-trinitro-1,3,5-triazine in the western fence lizard (sceloporus occidentalis). | hexahydro-1,3,5-trinitro-1,3,5-triazine (rdx) has been widely used as an explosive in munition formulations, resulting in contamination of wildlife habitat on military installations. to estimate health effects for reptilian species, acute, subacute, and subchronic oral toxicity studies were conducted using the western fence lizard (sceloporus occidentalis). estimated oral median lethal doses were 72 (95% confidence interval [ci], 49-106) mg/kg body weight (slope, 3.754) for males and 88 (95% ci, ... | 2009 | 19102580 |
| feeding preferences of the immature stages of three western north american ixodid ticks (acari) for avian, reptilian, or rodent hosts. | larval and nymphal ixodes pacificus cooley and kohls, i. (ixodes) jellisoni cooley and kohls, and dermacentor occidentalis marx were tested for host preference when simultaneously presented with a deer mouse (peromyscus maniculatus wagner), california kangaroo rat (dipodomys californicus merriam), western fence lizard (sceloporus occidentalis baird and girard), and california towhee (pipilo crissalis vigors) in an experimental apparatus. differences were observed in the preferences among the thr ... | 2009 | 19198525 |
| use of tricaine methanesulfonate (ms222) for euthanasia of reptiles. | tricaine methanesulfonate (ms222) injected into the intracoelomic cavity of reptiles was evaluated as a chemical euthanasia method. three western fence lizards, 2 desert iguanas, 4 garter snakes, and 6 geckos were euthanized by intracoelomic injection of 250 to 500 mg/kg of 0.7% to 1% sodium-bicarbonate-buffered ms222 solution followed by intracoelomic injection of 0.1 to 1.0 ml unbuffered 50% (v/v) ms222 solution. a simple 2-stage protocol for euthanasia of reptiles by using ms222 is outlined. ... | 2009 | 19245747 |
| reptile infection with anaplasma phagocytophilum, the causative agent of granulocytic anaplasmosis. | granulocytic anaplasmosis (ga) is a potentially fatal tick-borne rickettsial disease that occurs sporadically in the far western united states. we evaluated the prevalence of anaplasma phagocytophilum in multiple species of lizards and snakes from enzootic sites in northern california, described the infestation prevalence of its tick vector ixodes pacificus on reptiles, and conducted an experimental challenge of western fence lizards (sceloporus occidentalis) and pacific gopher snakes (pituophis ... | 2009 | 19281295 |
| reproductive and thyroid hormone profiles in captive western fence lizards (sceloporus occidentalis) after a period of brumation. | seasonal fluctuation in serum concentrations of sex steroid (testosterone [t] and 17beta-estradiol [e(2)]) and thyroid (triiodothyronine [t(3)] and thyroxine [t(4)]) hormones was determined in captive western fence lizards (sceloporus occidentalis). samples were collected from male and female breeding pairs weekly for a 4-month period after their emergence from artificial brumation. circulating levels of e(2) corresponded with the expected vitellogenic and ovulatory cycles in females, and surpri ... | 2008 | 19360602 |
| the effects of prey species on food conversion efficiency and growth of an insectivorous lizard. | little is known about the effects of different prey species on lizard growth. we conducted a 6-week study to determine the relative effects of prey species on growth parameters of hatchling western fence lizards, sceloporus occidentalis. lizards were fed house cricket nymphs, acheta domesticus, or mealworm larvae, tenebrio molitor. the effects of prey species on growth were determined by measuring prey consumption, gross conversion efficiency of food [gain in mass (g)/food consumed (g)], gain in ... | 2008 | 19360616 |
| clonal diversity of a malaria parasite, plasmodium mexicanum, and its transmission success from its vertebrate-to-insect host. | infections of the lizard malaria parasite plasmodium mexicanum are often genetically complex within their fence lizard host (sceloporus occidentalis) harbouring two or more clones of parasite. the role of clonal diversity in transmission success was studied for p. mexicanum by feeding its sandfly vectors (lutzomyia vexator and lutzomyia stewarti) on experimentally infected lizards. experimental infections consisted of one, two, three or more clones, assessed using three microsatellite markers. a ... | 2009 | 19523471 |
| effects of inorganic lead on western fence lizards (sceloporus occidentalis). | although anthropogenic pollutants are thought to threaten reptilian species, there are few toxicity studies on reptiles. we evaluated the toxicity of pb as lead acetate to the western fence lizard (sceloporus occidentalis). the acute lethal dose and sub-acute (14-day) toxicity studies were used to narrow exposure concentrations for a sub-chronic (60-day) study. in the sub-chronic study, adult and juvenile male lizards were dosed via gavage with 0, 1, 10 and 20 mg pb/kg-bw/day. mortality was limi ... | 2009 | 19631431 |
| geographic genetic differentiation of a malaria parasite, plasmodium mexicanum, and its lizard host, sceloporus occidentalis. | gene flow, and resulting degree of genetic differentiation among populations, will shape geographic genetic patterns and possibly local adaptation of parasites and their hosts. some studies of plasmodium falciparum in humans show substantial differentiation of the parasite in locations separated by only a few kilometers, a paradoxical finding for a parasite in a large, mobile host. we examined genetic differentiation of the malaria parasite plasmodium mexicanum, and its lizard host, sceloporus o ... | 2010 | 19916631 |
| toxicity of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (hmx) in three vertebrate species. | the explosive, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine or high-melting explosive (hmx), has been found in soils in areas used for testing and training by the military. many of these areas contain habitat for valued wildlife species. in an effort to better understand the environmental consequences from exposure, a reptilian (western fence lizard [sceloporus occidentalis]), an amphibian (red-backed salamander [plethodon cinereus]), and a mammalian species (rabbit [oryctolagus cuniculus]) ... | 2010 | 20012743 |
| effects of an invasive forest pathogen on abundance of ticks and their vertebrate hosts in a california lyme disease focus. | invasive species, including pathogens, can have important effects on local ecosystems, including indirect consequences on native species. this study focuses on the effects of an invasive plant pathogen on a vertebrate community and ixodes pacificus, the vector of the lyme disease pathogen (borrelia burgdorferi) in california. phytophthora ramorum, the causative agent of sudden oak death, is a non-native pathogen killing trees in california and oregon. we conducted a multi-year study using a grad ... | 2010 | 20941513 |
| toxic effects of oral 2-amino-4,6-dinitrotoluene in the western fence lizard (sceloporus occidentalis). | the compound 2-amino-4,6-dinitrotoluene (2a-dnt) was evaluated under laboratory conditions in the western fence lizard (sceloporus occidentalis) to assess the potential for reptile toxicity. oral ld(50) values were 1406 and 1867 mg/kg for male and female lizards, respectively. based on responses from a 14-day subacute study, a 60-day subchronic experiment followed where lizards were orally dosed at 0, 5, 15, 20, 25, 30 mg/kg-d. at day 60, number of days and survivors, food consumption, and chang ... | 2011 | 21067851 |
| impact of the experimental removal of lizards on lyme disease risk. | the distribution of vector meals in the host community is an important element of understanding and predicting vector-borne disease risk. lizards (such as the western fence lizard; sceloporus occidentalis) play a unique role in lyme disease ecology in the far-western united states. lizards rather than mammals serve as the blood meal hosts for a large fraction of larval and nymphal western black-legged ticks (ixodes pacificus-the vector for lyme disease in that region) but are not competent reser ... | 2011 | 21325326 |
| relative clonal proportions over time in mixed-genotype infections of the lizard malaria parasite plasmodium mexicanum. | vertebrate hosts of malaria parasites (plasmodium) often harbour two or more genetically distinct clones of a single species, and interaction among these co-existing clones can play an important role in plasmodium biology. however, how relative clonal proportions vary over time in a host is still poorly known. experimental mixed-clone infections of the lizard malaria parasite, plasmodium mexicanum, were followed in its natural host, the western fence lizard using microsatellite markers to determ ... | 2011 | 21396372 |