| repetitive dna and feulgen hydrolysis kinetics in three species of bufo. | two north american species of the genus bufo (bufo cognatus and bufo boreas, 2n = 22) and one african species (bufo regularis, 2n = 20) were analyzed with respect to their repetitive dna fractions and the behaviour of their chromatin to the acid hydrolysis at different times. the mean melting point of the total isolated dna decreased from 89 degrees c to 87 degrees c with a genome size increase from 4.4 to 7.5 pg. the differences in genome size can only partly be explained on the basis of repeti ... | 1979 | 93962 |
| larval hannemania sp. infestations of spea spp. in the southern high plains, texas, usa. | we describe a case history of larval hannemania sp. (acari: trombiculidae) infestations in two spadefoot toads (spea spp. anura: pelobatidae) captured from playa wetlands in the southern high plains, texas. hannemania sp. larvae were superficially attached to the skin, not encysted, and dermal changes were not observed. gross field examinations revealed a presumed occurrence of hannemania sp. in spea spp. at four of 24 wetlands in 2003 and 2004. although other species of amphibians were present ... | 2007 | 17984273 |
| comparative in vitro and in vivo effects of chlorpyrifos oxon in the outbred cd-1 mouse (mus musculus) and great plains toad (anaxyrus cognatus). | we compared biochemical, functional, and behavioral responses to the organophosphorus anticholinesterase chlorpyrifos oxon (cpo) in mice (mus musculus, cd-1) and toads (anaxyrus cognatus, great plains toad). toads were substantially less sensitive to acute lethality of cpo based on the maximum tolerated (nonlethal) dose (toads, 77 mg/kg; mice, 5.9 mg/kg). sublethal exposures led to classical signs of toxicity (increased involuntary movements, autonomic secretions) in mice but hypoactivity in toa ... | 2018 | 29573455 |
| osmotic tolerance of the muscles of two desert-inhabiting toads, bufo cognatus and scaphiopus couchi. | | 1964 | 14206962 |
| some physiological responses to anoxia in the great plains toad, bufo cognatus. | | 1971 | 4150227 |
| dna replication in the amphibia. | autoradiographic techniques were used to measure rate of replication and length of the replication unit in cultured cells of scaphiopus couchi, bufo cognatus, rana clamitans, and triturus viridescens, having nuclear dna amounts in the ratio 1:4:7:39 respectively. the autoradiographic experiments were designed to show whether the larger amounts of nuclear dna are correlated with more rapid rates of synthesis and/or with longer replication units. -- the dna replication rate was 2.5 mu/minute (corr ... | 1975 | 125187 |
| adrenergic control of the anuran cutaneous hydroosmotic response. | adrenergic effectors were shown to play a major role in increasing cutaneous water uptake (the hydroosmotic response) in dehydrated anurans. a beta-adrenergic antagonist, propranolol, blocked 61% of the cutaneous response to dehydration and 67% of the response elicited by salt loading in the toad bufo cognatus. a beta-adrenergic agonist, isoproterenol, elicited a response in normally hydrated animals equal to the propranolol-sensitive portion of the cutaneous hydroosmotic response of dehydrated ... | 1984 | 6321296 |
| blood changes in bufo cognatus following acute heat stress. | 1. various blood constituents were measured in an attempt to identify the effects of exposure of great plains toads to the critical thermal maximum (ctmax) and determine the time course of the onset of and recovery from these effects. 2. tests for generalized tissue damage including serum glutamic-oxalacetic and glutamic-pyruvic transaminases (sgot, sgpt), total protein and blood urea nitrogen (bun) were unaffected by acute thermal stress. 3. hematocrit, erythrocyte number, mean cell volume and ... | 1987 | 2886284 |
| angiotensin ii induces water absorption behavior in two species of desert anurans. | the octapeptide, angiotensin ii (a-ii), induces drinking behavior in several vertebrate species; however, relatively little is understood about a-ii-induced thirst in amphibians. scaphiopus couchii and bufo cognatus were dehydrated to 90% of their ad libitum weight. this level of dehydration was sufficient to induce water absorption response (wr) behavior in both species. fully hydrated toads injected intraperitoneally with a-ii exhibited a significant amount of wr behavior. the minimum effectiv ... | 1994 | 8034281 |
| freezing tolerance/intolerance and cryoprotectant synthesis in terrestrially overwintering anurans in the great plains, usa. | mechanistic bases for freezing tolerance in anurans have been well-studied only in wood frogs, rana sylvatica, so comprehensive explanations for the mechanisms and evolution of freezing tolerance in anurans are lacking. we measured crystallization temperatures, freezing tolerance/intolerance, and tissue glucose and glycogen phosphorylase activities in frozen and unfrozen winter-acclimated pseudacris triseriata, bufo cognatus and b. woodhousei. freezing occurred at higher subzero temperatures on ... | 1996 | 8766908 |
| the effects of melanocortin peptides and corticosterone on habituation in the great plains toad, bufo cognatus. | we investigated the ability of various melanocortin peptides and corticosterone to influence habituation of prey-catching behavior in the toad, bufo cognatus. male toads were injected with various melanocortin peptide fragments or corticosterone 30 min prior to acquisition. adrenocorticotropin (acth[1-39]), acth[4-10], and n-acetyl acth[1-13] amide (alpha-msh) significantly decreased the number of turning reactions during acquisition in relation to controls. the effects of the noncorticotropic a ... | 1996 | 8918679 |
| alterations in brain and plasma concentrations of alpha-melanocyte-stimulating hormone during habituation of prey-catching behavior in toads. | alpha-melanocyte-stimulating hormone (alpha-msh) and adrenocorticotropin (acth) promote habituation of prey-catching behavior in toads. we tested the hypothesis that habituation is associated with alterations in the activity of alpha-msh neurons in a toad, bufo cognatus. we used immunocytochemistry and ria to determine the organization and distribution of alpha-msh neurons in the brain. in addition, we measured brain alpha-msh and plasma concentrations in toads at different times before and duri ... | 1997 | 9063593 |
| differential effects of arginine vasotocin and gonadotropin-releasing hormone on sexual behaviors in an anuran amphibian. | both arginine vasotocin (avt) and gonadotropin-releasing hormone (gnrh) are known to influence sexual behavior in many vertebrate taxa. we investigated the effects of both of these peptides on two different sexual behaviors, calling and amplexus, in the great plains toad (bufo cognatus). avt, at a dosage of 100 microg/100 g toad, significantly increased both the amount of calling behavior per individual and the probability that an individual would call. gnrh, however, had no effect on calling be ... | 1997 | 9367717 |
| elevated corticosterone levels elicit non-calling mating tactics in male toads independently of changes in circulating androgens. | competition among males for a limited number of females may result in the expression of condition-dependent alternative mating tactics. in such cases, decision rules mediating mating tactic expression are likely to be influenced by a male's external as well as internal environment. for example, experimental studies with anuran amphibians (frogs and toads) indicate that changes in the social-acoustic environment alter the probability that an individual adopts a calling versus non-calling "satelli ... | 2006 | 16256990 |
| influence of land use on metal concentrations in playa sediments and amphibians in the southern high plains. | the southern high plains (shp) is a semi-arid region in which playa wetlands are the focal points of biodiversity. playas are highly influenced by surrounding land use. most of the shp is in agricultural production (primarily cotton) with a history of arsenic-containing herbicide use. metals influence reproduction and development in amphibians. we analyzed metal residues in playa sediment and whole body tissue of spea spp. and bufo cognatus metamorphs from two land uses: cropland and native gras ... | 2006 | 16513233 |
| stress hormone is implicated in satellite-caller associations and sexual selection in the great plains toad. | the effects of androgens on male-typical traits suggest that variation among males in circulating levels can play a major role in sexual selection. we examined whether variation in vocal attractiveness is attributable to differences in androgen levels among great plains toads (bufo cognatus). we found that noncalling "satellite" males practicing an alternative mating tactic were more likely to associate with males producing long calls. however, callers with satellites did not have higher androge ... | 2006 | 17004216 |
| toxicity of a glufosinate- and several glyphosate-based herbicides to juvenile amphibians from the southern high plains, usa. | pesticide toxicity is often proposed as a contributing factor to the world-wide decline of amphibian populations. we assessed acute toxicity (48 h) of a glufosinate-based herbicide (ignite 280 sl) and several glyphosate-based herbicide formulations (roundup weathermax, roundup weed and grass killer super concentrate, roundup weed and grass killer ready-to-use plus on two species of amphibians housed on soil or moist paper towels. survival of juvenile great plains toads (bufo cognatus) and new me ... | 2009 | 19000631 |
| population differentiation of temperate amphibians in unpredictable environments. | amphibians are a globally distributed and diverse lineage, but much of our current understanding of their population genetic structure comes from studies in mesic temperate habitats. we characterize the population genetic structure of two sympatric explosive breeding amphibians in the southwestern deserts of the united states: the great plains toad (anaxyrus cognatus) and couch's spadefoot toad (scaphiopus couchii). for both species, we find limited genetic differentiation even between populatio ... | 2009 | 19573030 |
| acute toxicity of three strobilurin fungicide formulations and their active ingredients to tadpoles. | fungicide applications in the united states have increased tenfold in the last 5 years. formulations and active ingredients (ais) have been demonstrated to cause acute mortality to amphibian life stages. however, there has been little to no discrimination between the toxicity of fungicide formulations and their ais. therefore, we compared the acute toxicity of the active ingredients and formulations of the fungicides headline®, stratego®, and quilt® using bufo cognatus tadpoles exposed to four c ... | 2012 | 22526924 |
| chronic effects of strobilurin fungicides on development, growth, and mortality of larval great plains toads (bufo cognatus). | agricultural fungicide application has increased tenfold since 2005 in the united states. active ingredients and formulations of strobilurin fungicides at environmentally relevant concentrations cause mortality to larval and metamorph amphibians; however, little is known about chronic exposure effects in amphibians. we exposed larval amphibians (bufo cognatus) throughout metamorphosis to the common fungicide formulations headline(®), stratego(®), quilt(®), and a control to determine effects on d ... | 2014 | 24522617 |
| factors influencing the toxicity of headline® fungicides to terrestrial stage toads. | amphibians are susceptible to exposure from contaminants via multiple pathways. pyraclostrobin fungicides have been shown to be toxic to terrestrial amphibians at environmentally relevant concentrations; however, these studies did not account for factors that may influence exposure and effects, such as fungicide formulation, age of the individual, exposure route, and physiological state of the individual. we examined headline® and headline amp® fungicide toxicity to adult anaxyrus cognatus and a ... | 2017 | 28370439 |
| seasonal effects of dehydration on glucose mobilization in freeze-tolerant chorus frogs (pseudacris triseriata) and freeze-intolerant toads (bufo woodhousii and b. cognatus). | it has been hypothesized that freeze-tolerance in anurans evolved from a predisposition for dehydration tolerance. to test this hypothesis, we dehydrated summer/fall-collected and winter acclimated freeze-tolerant chorus frogs and dehydration-tolerant, but freeze-intolerant, woodhouse's and great plains toads to 25% and 50% body water loss (bwl). following treatments, we measured glucose, glycogen, and glycogen phosphorylase and glycogen synthetase (summer/fall only) activities in liver and leg ... | 2004 | 15181646 |
| metacercariae of clinostomum attenuatum in ambystoma tigrinum mavortium, bufo cognatus and spea multiplicata from west texas. | tissues from barred tiger salamanders (ambystoma tigrinum mavortium), great plains toads (bufo cognatus) and new mexico spadefoots (spea multiplicata) collected from 16 playa wetlands in texas during 1999 and 2000 were examined by light microscopy. digenean cysts were primarily distributed subcutaneously throughout the specimens and occasionally coelomic invasion was noted. the parasites within the cysts were 1.5-2 mm in diameter, with a thin (c. 10 microm wide) eosinophilic-staining tegument, t ... | 2004 | 15575998 |
| effects of meal size, meal type, and body temperature on the specific dynamic action of anurans. | specific dynamic action (sda), the increase in metabolism stemming from meal digestion and assimilation, varies as a function of meal size, meal type, and body temperature. to test predictions of these three determinants of sda, we quantified and compared the sda responses of nine species of anurans, bombina orientalis, bufo cognatus, ceratophrys ornata, dyscophus antongilli, hyla cinerea, kassina maculata, kassina senegalensis, pyxicephalus adspersus, and rana catesbeiana subjected to meal size ... | 2007 | 17106741 |