| turgid female toads give males the slip: a new mechanism of female mate choice in the anura. | in many anuran species, males vocalize to attract females but will grasp any female that comes within reach and retain their hold unless displaced by a rival male. thus, female anurans may face strong selection to repel unwanted suitors, but no mechanism is known for doing so. we suggest that a defensive trait (the ability to inflate the body to ward off attack) has been co-opted for this role: by inflating their bodies, females are more difficult for males to grasp and hence, it is easier for a ... | 2010 | 20053661 |
| z and w sex chromosomes in the cane toad (bufo marinus). | the cane toad (bufo marinus) is one of the most notorious animal pests encountered in australia. members of the genus bufo historically have been regarded as having genotypic sex determination with male homogamety/female heterogamety. nevertheless, as with many toads, karyotypic analyses of the cane toad have so far failed to identify heteromorphics sex chromosomes. in this study, we used comparative genomic hybridization, reverse fluorescence staining, c-banding, and morphometric analyses of ch ... | 2009 | 19936947 |
| testosterone secretion and pharmacological spermatozoal recovery in the cane toad (bufo marinus). | the cane toad (bufo marinus) was used as a model to study male anuran reproductive endocrinology and to develop a protocol for non-invasive sperm recovery. circulating testosterone concentrations in 6-hourly samples did not vary significantly (p < 0.05) over a 24 h period although there was a tendency (p = 0.06) for testosterone to be elevated at 19:00 h relative to other times of the day, which may be related to the nocturnal activity pattern of this species. testosterone secretion after intrap ... | 2005 | 16257605 |
| anatomical organization of brainstem circuits mediating feeding motor programs in the marine toad, bufo marinus. | the goal of our research has been to investigate the neuronal integration that coordinates feeding movements in the marine toad (genus bufo). using injections of fluorescein dextran amines, combined with activity-dependent uptake of sulforhodamine 101, peripheral hypoglossal and trigeminal nerves involved with tongue and jaw movements were labeled. we identified the rostrocaudal distribution of hypoglossal and trigeminal motor nuclei, and their sensory projections. we also identified the extent ... | 2009 | 19703424 |
| cloning and expression of candidate sexual development genes in the cane toad (bufo marinus). | the development of the reproductive system in bufonids (true toads) is unique in several respects: sexual differentiation occurs later than in other anurans, and toads develop a bidder's organ, a rudimentary ovary that can be manipulated in males to produce mature oocytes. to illuminate the genesis of this unusual reproductive system, we isolated from the cane toad (bufo marinus) the orthologues of several known vertebrate sex-determining genes, determined their primary structure, and studied th ... | 2009 | 19653320 |
| sodium pump molecular activity and membrane lipid composition in two disparate ectotherms, and comparison with endotherms. | previous research has shown that the lower sodium pump molecular activity observed in tissues of ectotherms compared to endotherms, is largely related to the lower levels of polyunsaturates and higher levels of monounsaturates found in the cell membranes of ectotherms. marine-based ectotherms, however, have very polyunsaturated membranes, and in the current study, we measured molecular activity and membrane lipid composition in tissues of two disparate ectothermic species, the octopus (octopus v ... | 2005 | 15726386 |
| osmotically absorbed water preferentially enters the cutaneous capillaries of the pelvic patch in the toad bufo marinus. | cutaneously absorbed water in anurans has two potential routes of movement from the skin interstitium into the body fluids, via the cutaneous capillaries and/or the lymphatic system. we investigated the lymphatic route at the pelvic patch skin under the influence of isoproterenol and arginine vasotocin in bufo marinus by continuously aspirating lymph from the lymph sacs draining the pelvic patch while the animals absorbed water. changes in body mass, lymph mass, and lymph osmolality were measure ... | 2013 | 15702461 |
| impact of invasive cane toads on australian birds. | the cane toad (bufo marinus), a large, toxic, american anuran, was introduced to australia in 1935. populations of many of australia's reptiles (snakes, varanid lizards, crocodiles) and carnivorous mammals (dasyurid marsupials) have declined because these predators are killed by the toad's powerful toxins. in contrast to these well-studied species, little is known about the cane toads impacts on australian birds. we reviewed published and unpublished data on behavioral interactions between austr ... | 2009 | 19508674 |
| microbial biotransformation as a source of chemical diversity in cane toad steroid toxins. | the cane toad is an invasive pest that is rapidly colonising northern australia. the cane toad parotoid gland secretes cardiotoxic steroids (bufadienolides) that are poisoning native predator species. this study reveals bufadienolide diversity within the secretions of australian cane toads is different to cane toads from overseas, being far more structurally diverse than previously assumed. it is proposed that this variation is mediated by in situ bacterial biotransformation. | 2009 | 19216077 |
| factors influencing responses to alarm pheromone by larvae of invasive cane toads, bufo marinus. | if pheromonal communication systems of invasive species differ from those of native biota, it may be possible to control the invader by exploiting that difference. when injured, the larvae of cane toads, bufo marinus, an invasive species of major concern in tropical australia, produce species-specific chemical cues that alert conspecific tadpoles to danger. repeated exposure to the alarm chemical reduces tadpole survival rates and body sizes at metamorphosis and, thus, could help control toad po ... | 2009 | 19184225 |
| agriculture alters gonadal form and function in the toad bufo marinus. | many agricultural contaminants disrupt endocrine systems of wildlife. however, evidence of endocrine disruption in wild amphibians living in agricultural areas has been controversial. typically, studies on the effects of pollutants on wildlife attempt to compare polluted with unpolluted sites. | 2008 | 19057706 |
| neurally-derived nitric oxide regulates vascular tone in pulmonary and cutaneous arteries of the toad, bufo marinus. | in this study, the role of nitric oxide (no) in regulation of the pulmocutaneous vasculature of the toad, bufo marinus was investigated. in vitro myography demonstrated the presence of a neural no signaling mechanism in both arteries. vasodilation induced by nicotine was inhibited by the soluble guanylyl cyclase (gc) inhibitor, 1h-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one, and the no synthase (nos) inhibitor, n(omega)-nitro-l-arginine (l-nna). removal of the endothelium had no significant effect ... | 2008 | 18753269 |
| genes induced during the early developmental stages of the cane toad, bufo (chaunus) marinus. | metamorphosis, a critical stage in the development of toads and frogs, involves rapid levels of morphological change. in the current study, we have used microarray analysis to identify shifts in gene expression between tadpole and toadlet stages of the cane toad, bufo (chaunus) marinus. here, we report on nine genes that show the greatest induction during metamorphosis; the gut-associated gastrokine and trefoil factor, blood components haemoglobins alpha/beta, apolipoprotein and serum albumin, a ... | 2008 | 18541458 |
| the effects of fasting and cold exposure on metabolic rate and mitochondrial proton leak in liver and skeletal muscle of an amphibian, the cane toad bufo marinus. | futile cycling of protons across the mitochondrial inner membrane contributes significantly to standard metabolic rate in a variety of ectothermic and endothermic animals, but adaptations of the mitochondrial bioenergetics to different environmental conditions have rarely been studied in ectotherms. changes in ambient temperature and nutritional status have a great effect on the physiological demands of ectothermic amphibians and may require the adjustment of mitochondrial efficiency. in order t ... | 2008 | 18515721 |
| abiotic and biotic influences on the dispersal behavior of metamorph cane toads (bufo marinus) in tropical australia. | a mechanistic understanding of factors influencing the dispersal behavior of metamorph cane toads (bufo marinus) has direct conservation relevance in australia. these invasive anurans are toxic to native predators, and if we can predict their distribution across the landscape, we can also predict (and perhaps, manage) the scale of their impact. we propose that the major drivers of metamorph distribution are the risk of dehydration (restricting the young toads to moist substrates near pond margin ... | 2008 | 18288694 |
| role for the skeletal muscle action potential in non-hebbian long-term depression at the amphibian (bufo marinus) neuromuscular junction. | retrograde signaling from skeletal muscle cells to motor nerve terminals is a recognized mechanism for modulating the strength of neuromuscular transmission. we recently described a form of long-term depression of transmitter release at the mature neuromuscular junction that is dependent on the production of nitric oxide, most likely by the muscle cell (etherington and everett 2004 j physiol (lond) 559:507-517). we now show that the depression is blocked by treating neuromuscular preparations wi ... | 2008 | 18240324 |
| chronic hypoxic hypercapnia modifies in vivo and in vitro ventilatory chemoreflexes in the cane toad. | previous studies have shown that exposure to chronic hypoxia (ch) and chronic hypercapnia (chc) alone have opposite effects on central respiratory-related ph/co(2) chemosensitivity in the cane toad (bufo marinus). this study examined the effects of chronic hypoxic hypercapnia (chh) on central ph/co(2) chemosensitivity. cane toads were maintained at 10% o(2) and 3.5% co(2) for 10 days. changes in central ph/co(2)-sensitive fictive breathing were measured using in vitro brainstem-spinal cord prepa ... | 2008 | 18068556 |
| oxygen-sensitive regulatory volume increase and na transport in red blood cells from the cane toad, bufo marinus. | the red blood cells (rbcs) of cane toad, bufo marinus, are only partially saturated with oxygen in most of the circulation due to cardiac shunts that cause desaturation of arterial blood. the present study examines the oxygen dependency of rbc ouabain-insensitive unidirectional na transport, using 22na, in control cells and in cells exposed to hyperosmotic shrinkage or the beta-adrenergic agonist isoproterenol. deoxygenation per se induced a slow, but significant na influx, which was paralleled ... | 2007 | 17575034 |
| optimisation of handling, activation and assessment procedures for bufo marinus spermatozoa. | in the present study, we investigated handling, activation and assessment procedures for cane toad (bufo marinus) spermatozoa. optimisation of these techniques will facilitate the maintenance of sperm viability during cryopreservation and during in vitro fertilisation (ivf) techniques in reproduction technologies for endangered species. spermatozoa were taken from testicular macerates and assessed using plasma membrane integrity assays (live/dead stains) and quantitative scores of motility param ... | 2007 | 17524305 |
| mechanisms of calcium sequestration during facilitation at active zones of an amphibian neuromuscular junction. | the calcium transients (delta[ca(2+)](i)) at active zones of amphibian (bufo marinus) motor-nerve terminals that accompany impulses, visualized using a low-affinity calcium indicator injected into the terminal, are described and the pathways of subsequent sequestration of the residual calcium determined, allowing development of a quantitative model of the sequestering processes. blocking the endoplasmic reticulum calcium pump with thapsigargin did not affect delta[ca(2+)](i) for a single impulse ... | 2007 | 17462674 |
| immunolocalization and mrna expression of the epithelial na+ channel alpha-subunit in the kidney and urinary bladder of the marine toad, bufo marinus, under hyperosmotic conditions. | the amiloride-sensitive epithelial sodium channel (enac) has previously been shown to be involved in the maintenance of body fluid volume and in na(+) absorption across the skin and urinary bladder in amphibians. however, the function and distribution of enac have not been clearly described in amphibian kidney. we therefore cloned the enac alpha-subunit cdna from kidney of the marine toad, bufo marinus. the enac mrna and protein were abundantly expressed in the kidney and in the urinary bladder ... | 2007 | 17333031 |
| arginine vasotocin promotes urea permeability through urea transporter expressed in the toad urinary bladder cells. | we previously isolated a cdna of a urea transporter (bufo ut) from the kidney of the marine toad, bufo marinus, and demonstrated that the bufo ut was specifically localized on the epithelial membrane of the early distal tubules in the kidney and urinary bladder. in the present study, the function of bufo ut was investigated using a xenopus oocytes expression system. further, we examined the effects of arginine vasotocin (avt) on urea transport in isolated cells from the toad urinary bladder. whe ... | 2015 | 17270186 |
| afferent input modulates the chronic hypercapnia-induced increase in respiratory-related central ph/co2 chemosensitivity in the cane toad (bufo marinus). | the goal of this study was to examine the role of respiratory-related afferent input on the chronic hypercapnia (chc)-induced increase in central respiratory-related ph/co2 chemosensitivity in cane toads (bufo marinus). toads were exposed to chc (3.5% co2) for 10 days, following which in vitro brainstem-spinal cord preparations were used to assess central respiratory-related ph/co2 chemosensitivity. motor output from the vagus nerve root was used as an index of breathing (fictive breathing). olf ... | 2007 | 17210960 |
| the role of hind limb flexor muscles during swimming in the toad, bufo marinus. | most work examining muscle function during anuran locomotion has focused largely on the roles of major hind limb extensors during jumping and swimming. nevertheless, the recovery phase of anuran locomotion likely plays a critical role in locomotor performance, especially in the aquatic environment, where flexing limbs can increase drag on the swimming animal. in this study, i use kinematic and electromyographic analyses to explore the roles of four anatomical flexor muscles in the hind limb of b ... | 2007 | 17182235 |
| chronic hypoxia attenuates central respiratory-related ph/co2 chemosensitivity in the cane toad. | this study examined the effects of chronic hypoxia (ch) and mid-brain transection on central respiratory-related ph/co(2) chemosensitivity in cane toads (bufo marinus). toads were exposed to 10 days of ch (10% o(2)) following which in vitro brainstem-spinal cord preparations, with the mid-brain attached, were used to examine central ph/co(2) chemosensitivity. a reduction in artificial cerebral spinal fluid (acsf) ph increased fictive breathing frequency (fr) and total fictive ventilation. ch red ... | 2007 | 17140861 |
| complementary and lateralized forms of processing in bufo marinus for novel and familiar prey. | amphibian vision is one of the most comprehensively studied of all vertebrate sensory systems. however, the processes of object recognition and memory in anuran amphibians have resisted satisfactory explanation. our research shows that insight to the issue of visual discrimination and recognition in toads may be gained by investigation of the specialized and complementary functions carried out by the left and right brain hemispheres. we report that specialized processes associated with the left ... | 2006 | 16631392 |
| chronic hypercapnia modulates respiratory-related central ph/co2 chemoreception in an amphibian, bufo marinus. | anuran amphibians have multiple populations of ph/co2-sensitive respiratory-related chemoreceptors. this study examined in cane toads (bufo marinus) whether chronic hypercapnia (chc) altered the ph/co2 sensitivity of central respiratory-related chemoreceptors in vitro and whether chc altered the acute hypercapnic ventilatory response (hcvr; 5% co2) in vivo. toads were exposed to chc (3.5% co2) for 9 days. in vitro brainstem-spinal cord preparations were used to examine central respiratory-relate ... | 2006 | 16513940 |
| effects of azadirachtin on mortality, fertilization, and swimming speed in larvae of the cane toad, bufo marinus (anura: bufonidae). | experiments were conducted to assess the effects of azadirachtin (az) on survival capacity, fertilization success, and swimming speed in larval stages of the cane toad, bufo marinus . lc50 values (96-hr) for various larval stages exposed to 0.50 mg/l az were as follows: 5.35 (stage 12), 5.77 (stage 16), 787 (stage 20), 13.43 (stage 24), and 21.54 (stage 30). tadpoles did not exhibit any apparent disorientation or production of mucous in response to az concentrations ranging from 0.3 to 0.5 mg/l. ... | 2005 | 16459558 |
| electrophoretic and functional identification of two troponin c isoforms in toad skeletal muscle fibers. | the differential sensitivity of frog twitch and slow-tonic fibers to ca(2+) and sr(2+) suggests that these two fiber types express different troponin c (tnc) isoforms. to date, only one tnc isoform from anurans (resembling the mammalian fast-twitch isoform) has been isolated and characterized. in this study, we examined the possibility that anuran striated muscle contains more than one tnc isoform. toward this end, we determined the tnc isoform composition of 198 single fibers from the rectus ab ... | 2006 | 16176967 |
| morphological recovery in the reattached retina of the toad bufo marinus: a new experimental model of retinal detachment. | the retinal pigment epithelium (rpe) of the toad (bufo marinus) has been used in many studies as a model for understanding its role and interaction with the neural retina. the toad's retina has been used to establish a new in vitro model of experimental retinal detachment (rd) and replacement . it has been shown that the electrophysiological measures of retinal function recovered following complete rd. the toad was chosen because its rpe is similar to the mammalian rpe . in this report, light mi ... | 2008 | 15847941 |
| cyanide inhibits the na+/ca2+ exchanger in isolated cardiac pacemaker cells of the cane toad. | the effects of the metabolic inhibition on the activity of the na+/ca2+ exchanger (ncx) were studied in single isolated pacemaker cells from the cane toad. ca2+ influx on ncx (reverse mode) was estimated by measuring the increase in intracellular calcium concentration ([ca2+]i) in response to extracellular na+-free solution. after application of 2 mm sodium cyanide for 3-5 min, the peak [ca2+]i in na+-free solution was significantly decreased from 377+/-42 nm to 260+/-46 nm, suggesting inhibitio ... | 2005 | 15688245 |
| effects of ozone exposure on nonspecific phagocytic capacity of pulmonary macrophages from an amphibian, bufo marinus. | pulmonary macrophages are an important component of immune defense against inhaled foreign particles and microorganisms. in humans and other mammals, exposure to moderate amounts of ozone (o3) can inhibit functional capacities of alveolar macrophages. in many wilderness areas downwind of urban centers, ozone levels frequently exceed national standards. we report results of 4-h inhalation exposures to 0.8 parts per million o3 on pulmonary macrophage viability and phagocytosis capacity in marine t ... | 2005 | 15683185 |
| chronic hypoxia modulates nmda-mediated regulation of the hypoxic ventilatory response in an amphibian, bufo marinus. | this study examined whether a hypoxia-tolerant amphibian, the cane toad, undergoes mammalian-like ventilatory acclimatisation to hypoxia (vah) and whether chronic hypoxia (ch) alters nmda-mediated regulation of the acute hypoxic ventilatory response (hvr). toads were exposed to 10 days of ch (10% o2) followed by acute hypoxic breathing trials or an intra-arterial injection of nacn. trials were conducted before and after i.p. treatment with an nmda-receptor channel blocker (mk801). ch blunted the ... | 2006 | 16344006 |
| the effect of n-ethylmaleimide on transmitter release from the skeletal neuromuscular junction of bufo marinus. | n-ethylmaleimide (nem) has been used extensively in biochemical assays as an inhibitor of the nem sensitive fusion protein (nsf). however, examination of the effect of nem on transmitter release in more physiologically relevant preparations has proved inconclusive. in the present study, we have examined the effect of low concentrations of nem on synaptic transmission in intact nerve-muscle preparations from toads (bufo marinus). under conditions of low transmitter release probability (0.3 mm cal ... | 2004 | 15236347 |
| acidosis counteracts the negative inotropic effect of k+ on ventricular muscle strips from the toad bufo marinus. | strenuous activity is associated with acidosis, increased extracellular potassium concentration ([k+]o), and elevated levels of circulating catecholamines. acidosis and elevated [k+]o are normally considered harmful to cardiac function, and a high sympathetic tone on the heart may lead to arrhythmia. during activity, however, the heart must be able to increase rate and strength of contraction. while the individual effects of [k+]o, acidosis, and adrenaline on contractile properties of cardiac mu ... | 2014 | 15095242 |
| schwann cell dynamics with respect to newly formed motor-nerve terminal branches on mature (bufo marinus) muscle fibers. | a study has been made of the formation of synaptic terminals from long processes formed at the end of motor nerve branches of endplates in mature amphibian (bufo marinus) muscle. injection of fluorescent dyes into individual motor axons showed the full extent of their branches at single endplates. synaptic vesicle clusters at these branches were identified with styryl dyes. some terminal branches consisted of well separated varicosities, each possessing a cluster of functioning synaptic vesicles ... | 2003 | 14724381 |
| cardiorespiratory effects of forced activity and digestion in toads. | digestion and physical activity are associated with large and sometimes opposite changes in several physiological parameters. gastric acid secretion during digestion causes increased levels of plasma bicarbonate ([hco-3](pl)), whereas activity leads to a metabolic acidosis with increased lactate and decrease in plasma bicarbonate. here we describe the combined effects of feeding and activity in the toad bufo marinus to investigate whether the increased bicarbonate buffering capacity during diges ... | 2013 | 13130426 |
| plasma aldosterone, angiotensin ii, and arginine vasotocin concentrations in the toad, bufo marinus, following osmotic treatments. | to clarify the physiological roles of the renin-angiotensin-aldosterone system (raas) and arginine vasotocin (avt) on body fluid regulation in amphibians, we measured plasma concentrations of aldosterone (aldo), angiotensin ii (ang ii), and avt after various osmotic challenges in the marine toad, bufo marinus (bufonidae). hematocrit value (ht) as an indicator of plasma volume, plasma osmolality and concentrations of plasma components (na(+), cl(-), k(+), and urea) were also measured. the toads w ... | 2005 | 15613270 |
| limb preference and skeletal asymmetry in the cane toad, bufo marinus (anura: bufonidae). | two forms of skeletal asymmetry were identified in a population of cane toads, bufo marinus, an exotic species in australia. fluctuating asymmetry characterised the lengths and weights of the long bones of the forelimbs and hindlimbs. directional asymmetry was observed in the structure of the pectoral girdle of the toads, with the right epicoracoid positioned ventral to the left epicoracoid in 88% of the skeletons examined. morphological data from a cohort of individuals were correlated with lim ... | 2002 | 15513201 |
| early effects of metabolic inhibition on intracellular ca2+ in toad pacemaker cells: involvement of ca2+ stores. | the early effects of metabolic inhibition on intracellular ca(2+) concentration ([ca(2+)](i)), ca(2+) current, and sarcoplasmic reticulum (sr) ca(2+) content were studied in single pacemaker cells from the sinus venosus of the cane toad. the amplitude of the spontaneous elevations of systolic [ca(2+)](i) (ca(2+) transients) was reduced after 5-min exposure to 2 mm nacn from 338 +/- 30 to 189 +/- 37 nm (p < 0.005, n = 9), and the spontaneous firing rate was reduced from 27 +/- 2 to 12 +/- 4 beats ... | 2003 | 12595299 |
| lymph heart scintigraphy in the toad. | to our knowledge, there are no reports on the use of radionuclide labeled agents to image the lymphatic system of anuran amphibia. lymphoscintigraphy was performed in 18 toads bufo marinus l, after the injection of tc-99m-serum albumin within the ventral lymph sac. images were obtained with a rectilinear scanner immediately after tracer administration. scintigrams were digitalized and densitometric profiles were obtained. one or more lymph hearts were demonstrated on all 18 scans. scintigrams sh ... | 2002 | 12570327 |
| cardiovascular responses to hypoxia and anaemia in the toad bufo marinus. | amphibians exhibit cardiorespiratory responses to hypoxia and, although several oxygen-sensitive chemoreceptor sites have been identified, the specific oxygen stimulus that triggers these responses remains controversial. this study investigates whether the cardiovascular response to oxygen shortage correlates with decreased oxygen partial pressure of arterial blood (pa(o(2))) or reduced oxygen concentration ([o(2)]) in toads. toads, equipped with blood flow probes and an arterial catheter, were ... | 2003 | 12547940 |
| resting respiratory behavior in minimally instrumented toads--effects of very long apneas on blood gases and ph. | resting respiratory behavior of bufo marinus in minimally instrumented toads is described for a period of 24 hours in which the animals are left undisturbed. torpor-related long apneas are described and their implications for blood gas levels are investigated. results show that the resting ventilation rate of bufo marinus is much lower than that reported so far. levels of arterial oxygen, carbon dioxide, and ph are monitored during artificial long apneas induced by anesthesia. the toads showed a ... | 2003 | 12914413 |
| ventilatory behaviors of the toad bufo marinus revealed by coherence analysis. | breathing in amphibians is a remarkably complex behavior consisting of irregular breaths that may be taken singly or in bouts that are used to deflate and inflate the lungs. the valves at the two outlets of the buccal cavity (nares and glottis) need to be finely controlled throughout the bout for the expression of these complex respiratory behaviors. in this study, we use a technique based on the calculation of the coherence spectra between respiratory variables (buccal pressure; narial airflow; ... | 2003 | 12914412 |
| modulation of breathing by phasic pulmonary stretch receptor feedback in an amphibian, bufo marinus. | this study examined the role of phasic pulmonary stretch receptor (psr) feedback in ventilatory control, breath clustering and breath timing in decerebrate, paralysed and artificially-ventilated cane toads (bufo marinus) under conditions designed to minimise tonic psr feedback. fictive breathing was recorded as trigeminal motor output to the buccal musculature. artificial tidal ventilation, with hypercarbic gas mixtures, was either continuous or activated by the fictive breaths and was manipulat ... | 2004 | 15450478 |
| postsynaptic production of nitric oxide implicated in long-term depression at the mature amphibian (bufo marinus) neuromuscular junction. | we report here evidence for endogenous no signalling in long-term (>1 h) synaptic depression at the neuromuscular junction induced by 20 min of 1 hz nerve stimulation. synaptic depression was characterized by a 46% reduction in the end-plate potential (epp) amplitude and a 21% decrease in miniature epp (mepp) frequency, but no change to mepp amplitude, indicating a reduction in evoked quantal release. both the membrane-impermeant no scavenger cptio and the nos inhibitor l-name blocked depression ... | 2004 | 15243135 |
| metabolic costs induced by lactate in the toad bufo marinus: new mechanism behind oxygen debt? | the mechanism of an increase in metabolic rate induced by lactate was investigated in the toad bufo marinus. oxygen consumption (vo(2)) was analyzed in fully aerobic animals under hypoxic conditions (7% o(2) in air), accompanied by measurements of catecholamines in the plasma, and was measured in isolated hepatocytes in vitro under normoxia by using specific inhibitors of lactate proton symport [alpha-cyano-4-hydroxycinnamate (chc)] and sodium proton exchange (eipa). the rise in metabolic rate i ... | 2003 | 12433869 |
| lymph osmolality and rehydration from nacl solutions by toads, bufo marinus. | toads, bufo marinus, allowed to maintain an ad libitum state of hydration were dehydrated by 10 15% of their standard weight and allowed to rehydrate from either deionized water or from 10 or 50 mmol l(-1) nacl solutions. toads rehydrating from the dilute salt solutions recovered a larger fraction of their standard weight than did toads rehydrating from deionized water despite there being a reduced osmotic gradient. amiloride did not reduce water gain from these solutions. water uptake from 100 ... | 2001 | 11409625 |
| myosin heavy chain isoform expression and ca2 +-stimulated atpase activity in single fibres of toad rectus abdominis muscle. | segments of single fibres from the rectus abdominis (ra) muscles of adult and juvenile cane toads (bufo marinus) were examined for myosin heavy chain (mhc) isoform expression and ca2+-stimulated mgatpase activity. mhc isoform analyses were carried out using the recently developed alanine-sds-page method, which separates one tonic (bmhct) and three twitch (bmhc1, bmhc2, bmhc3) mhc isoforms in toad skeletal muscle. ca2+-stimulated mgatpase activity was measured by spectrophotometric determination ... | 2002 | 12416721 |
| a comparison of sucrose, saline, and saline with egg-yolk diluents on the cryopreservation of cane toad (bufo marinus) sperm. | previous studies on cane toad (bufo marinus; bufonidae; anura) sperm cryopreservation were extended to compare the effects of cryopreservation in established sucrose (non-ionic) diluents with cryopreservation in ionic diluents containing amphibian ringer solutions (with and without egg-yolk). in addition, methanol was tested as a cryoprotectant for b. marinus sperm for the first time. twenty-seven cryoprotective solutions were trialled, with each containing one of the three diluents [10% (w/v) s ... | 2002 | 12237090 |
| [the glands of the dorso-distal mucosa of the toad bufo marinus (amphibia: anura) tongue: histology and ultrastructure ]. | frequently, the studies on the lingual epithelium ultrastructure in anurans do not show differences between filiform papilae and glandular epithelia in the non-sensory dorsal epithelium. to accomplish the study of glandular epithelium, samples of dorso-distalis mucosae of bufo marinus tongue were processed for transmission electron microscopy and also semithin sections of the same material were used for light microscopy study. the results showed that the glandular epithelium is constituted by th ... | 2002 | 12216500 |
| quantitative structure-activity analyses of bufokinin and other tachykinins at bufokinin (bnk1) receptors of the small intestine of the cane toad, bufo marinus. | the toad tachykinin, bufokinin (lys-pro-arg-pro-asp-gln-phe-tyr-gly-leu-met amide; buf), acts via tachykinin nk1-like receptors to contract the intestine of the cane toad, bufo marinus. in this structure-activity study, we used isolated segments of toad small intestine and performed binding studies with [125i] bolton-hunter buf in intestinal membranes to compare the contribution of individual amino acid residues to the potencies of 18 naturally occurring tachykinins and 13 buf analogs. potencies ... | 2005 | 15627485 |
| cysteine-scanning mutagenesis study of the sixth transmembrane segment of the na,k-atpase alpha subunit. | the accessibility of the residues of the sixth transmembrane segment (tm) of the bufo marinus na,k-atpase alpha subunit was explored by cysteine scanning mutagenesis. methanethiosulfonate reagents reached only the two most extracellular positions (t803, d804) in the native conformation of the na,k-pump. palytoxin induced a conductance in all mutants, including d811c, t814c and d815c which showed no active electrogenic transport. after palytoxin treatment, four additional positions (v805, l808, d ... | 2002 | 11904164 |
| effects of anaesthesia on blood gases, acid-base status and ions in the toad bufo marinus. | it is common practice to chronically implant catheters for subsequent blood sampling from conscious and undisturbed animals. this method reduces stress associated with blood sampling, but anaesthesia per se can also be a source of stress in animals. therefore, it is imperative to evaluate the time required for physiological parameters (e.g. blood gases, acid-base status, plasma ions, heart rate and blood pressure) to stabilise following surgery. here, we report physiological parameters during an ... | 2002 | 11867289 |
| effects of membrane cholesterol manipulation on excitation-contraction coupling in skeletal muscle of the toad. | 1. single mechanically skinned fibres and intact bundles of fibres from the twitch region of the iliofibularis muscle of cane toads were used to investigate the effects of membrane cholesterol manipulation on excitation-contraction (e-c) coupling. the cholesterol content of membranes was manipulated with methyl-beta-cyclodextrin (mbetacd). 2. in mechanically skinned fibres, depletion of membrane cholesterol with mbetacd caused a dose- and time-dependent decrease in transverse tubular (t)-system ... | 2001 | 11432993 |
| effects of temperature and oxygen availability on circulating catecholamines in the toad bufo marinus. | the release of catecholamines during hypoxia has received limited attention in amphibians and the adrenergic regulation of cardio-pulmonary functions is, therefore, not well understood at the organismic level. to describe the changes in plasma catecholamine concentrations, we exposed toads (bufo marinus) to different levels of hypoxia at two temperatures (15 and 25 degrees c). in addition, blood oxygen binding properties were determined in vitro at 15 and 25 degrees c at two different ph values. ... | 2001 | 11423317 |
| electrophysiological properties of the tongue epithelium of the toad bufo marinus. | the dorsal lingual epithelium from the tongue of the toad bufo marinus was mounted in an ussing-type chamber, and the short-circuit current (i(sc)) was measured using a low-noise voltage clamp. with nacl ringer bathing the mucosal and serosal surfaces of the isolated tissue, an outwardly directed (mucosa-positive) i(sc) was measured that averaged -10.71+/-0.82 microa cm(-2) (mean +/- s.e.m., n=24) with a resistance of 615+/-152 omega cm(2) (mean +/- s.e.m., n=10). substitution of chloride with s ... | 2002 | 12077171 |
| the effect of saccharides on the post-thaw recovery of cane toad (bufo marinus) spermatozoa. | the effect of monosaccharides (glucose, fructose) and disaccharides (maltose, sucrose, trehalose) as diluents, in cryoprotective additives containing 15% (v/v) dmso or glycerol as cryoprotectants, were investigated on the recovery of sperm motility after cryopreservation of cane toad (bufo marinus) spermatoazoa at low (approximately 5 degrees c/min(-1)) and high cooling rates (approximately 35 degrees c/min(-1)). the results show that: 1. recovery of percentage motility was higher with slow cool ... | 2003 | 12050780 |
| structural and mechanical aspects of the skin of bufo marinus (anura, amphibia). | specific biomechanical characters and some structures possibly related to them were investigated in the skin of the toad bufo marinus using tensile testing techniques (at constant strain till rupture) as well as morphological methods (histological, immunohistochemical and electronmicroscopical). mechanical parameters of the native skin varied considerably according to sex, individual variability and/or site of specimen collection. in skin strips of males and females excised from different parts ... | 2001 | 11949790 |
| [new observations on the structure of the lingual filiform papillae epithelium of the toad bufo marinus l.: light and transmission electron microscopy study]. | there are several inconsistencies and confusions about the microscopic structure in the anurans dorsal, non-sensory, mucosal epithelium of the tongue. the aim of this work was to differentiate the structure of the epithelium covering filiform papillae from the glandular epithelium. for this, samples of the dorsal distal mucosa of bufo marinus tongue were processed for light microscopy (lm) and transmission electron microscopy (tem). for lm, stained 1 micron sections were used. the results showed ... | 2001 | 11915447 |
| atp modulates intracellular ca2+ and firing rate through a p2y1 purinoceptor in cane toad pacemaker cells. | the effect of extracellular atp (10-100 microm) on intracellular ca2+ concentration ([ca2+]i) and firing rate has been studied in single pacemaker cells isolated from the sinus venosus of cane toads. in spontaneously firing cells, atp initially increased peak [ca2+]i by 43 +/- 5 %, increased diastolic [ca2+]i by 20 + 3 % and increased the firing rate by 58 +/- 8 %. these early effects were followed by a late phase in which both the peak [ca2+]i and the firing rate declined. adenosine, and utp (r ... | 2003 | 12949218 |
| [suggestive evidences for a microanatomical relationship between mast cells and nerve in the tongue of the toad bufo marinus demonstrated by means of high resolution light microscopy]. | mast cells are connective tissue cells, present in all vertebrates and characterized by the metachromatic stain of their granules. nowadays mast cells have been recognized as a potent cellular source of multiple cytokines, suggesting an important role in immunoregulation and host defense. these cells have been described as preferentially located around blood vessels but more recently close spatial relationship between mast cells and nerves has been reported mostly in mammalian species. the micro ... | 2002 | 12945491 |
| effects of ozone on evaporative water loss and thermoregulatory behavior of marine toads (bufo marinus). | ozone (o(3)) is a strong pulmonary irritant and causes a suite of respiratory tract inflammatory responses in humans and other mammals. in addition to lung injury, rodents exposed to o(3) exhibit a pronounced decrease in core body temperature at rest, which may offer a protective effect against o(3) damage. the effects of o(3) on other vertebrates have not been studied. compared to individuals exposed to air (n=34), bufo marinus toads exposed to o(3) (n=32) for 4 h lost 3.78 g body mass (adjuste ... | 2001 | 11453678 |
| the use of the indicator fluo-5n to measure sarcoplasmic reticulum calcium in single muscle fibres of the cane toad. | 1. single fibres from the lumbrical muscles of the cane toad (bufo marinus) were incubated in fluo-5n am for 2 h at 35 degrees c in order to load the indicator into the sarcoplasmic reticulum. fluo-5n is a low-affinity calcium indicator (k(ca) 90 microm). successful sarcoplasmic reticulum (sr) loading was indicated by a fluorescence signal that declined during contraction. 2. confocal microscopy showed that the dye loaded principally in lines perpendicular to the long axis of the fibre that repe ... | 2001 | 11432994 |
| effects of inhibition gastric acid secretion on arterial acid-base status during digestion in the toad bufo marinus. | digestion affects acid-base status, because the net transfer of hcl from the blood to the stomach lumen leads to an increase in hco3(-) levels in both extra- and intracellular compartments. the increase in plasma [hco3(-)], the alkaline tide, is particularly pronounced in amphibians and reptiles, but is not associated with an increased arterial ph, because of a concomitant rise in arterial pco2 caused by a relative hypoventilation. in this study, we investigate whether the postprandial increase ... | 2003 | 12829050 |
| role of environmental pollutants on immune functions, parasitic infections and limb malformations in marine toads and whistling frogs from bermuda. | soil, water, and amphibian tissues collected between 1995 and 1999 from 15 study sites in bermuda were analysed for pesticides and heavy metals. the most abundant pesticide residue in soil was p,p'-dichlorodiphenyldichloroethylene (dde) which was found at all sites in concentrations ranging from 0.003 to 4.023 p.p.m. no pesticide residues were found in water. dde was also recovered from the livers and fat bodies of marine toads (bufo marinus) and whistling frogs (eleutherodactylus johnstonei). a ... | 2003 | 12745335 |
| bidder's organ in the toad bufo marinus: effects of orchidectomy on the morphology and expression of lamina-associated polypeptide 2. | the bidder's organ is an undeveloped ovary located anterior to the testis in male true toads (bufonidae). the presence of sperm and oocytes, derived from the primordial germ cells of the male toad, provides an exceptional condition for the study of germ cell differentiation in vertebrates. in this study, the effects of orchidectomy on morphology and on lamina-associated polypeptide 2 (lap2) expression were investigated in the bidder's organ of bufo marinus. to characterize bidderian oocytes, oog ... | 2002 | 12492511 |
| storage of cane toad (bufo marinus) sperm for 6 days at 0 degrees c with subsequent cryopreservation. | we investigated the recovery of motility of cane toad (bufo marinus) sperm after storage for 6 days at 0 degree c (on ice) and after subsequent cryopreservation. sperm suspensions were prepared from testes macerated in either simplified amphibian ringer (sar) or 10% (w/v) sucrose diluents, with 15% or 20% (v/v) glycerol or me2so as cryoprotectants, and were stored for 6 days. alternatively, suspensions were prepared in either sar or 10% (w/v) sucrose diluent and stored for 6 days, after which so ... | 2002 | 12467350 |
| atp suppresses activity in slowly adapting but not rapidly adapting mechanoreceptors in toad skin. | to test the possible role of atp in transducing or modulating touch sensation, an isolated skin-nerve preparation from the toad, bufo marinus, perfused on the inner side, was used to examine the effects of atp on slowly adapting (sa) and rapidly adapting (ra) mechanoreceptors, identified by ramp and hold indentation of the skin. atp (1-50 mm) did not generate impulse activity in either sa or ra mechanoreceptors nor increase their responses to mechanical stimulation. instead, atp (> or =5 mm) rev ... | 2002 | 12167770 |
| inferring population history from microsatellite and enzyme data in serially introduced cane toads, bufo marinus. | much progress has been made on inferring population history from molecular data. however, complex demographic scenarios have been considered rarely or have proved intractable. the serial introduction of the south-central american cane toad bufo marinus in various caribbean and pacific islands involves four major phases: a possible genetic admixture during the first introduction, a bottleneck associated with founding, a transitory population boom, and finally, a demographic stabilization. a large ... | 2001 | 11779806 |
| the dynamics of venous return and response to hypervolemia in the toad, bufo marinus (l.). | venous return from the posterior region of amphibians travels by either two renal portal veins to the kidney or a central abdominal vein that drains into the hepatic portal system. the relative proportions of blood flow in these vessels has never been measured nor has a modification of flow been determined when venous return increases by changes in blood volume during hypervolemia or during increased volume input from the posterior lymph hearts. | 2001 | 11696249 |
| parallel metabotropic pathways in the heart of the toad, bufo marinus. | this study examined the transduction pathways activated by epinephrine in the pacemaker region of the toad heart. recordings of membrane potential, force, and intracellular ca(2+) concentration ([ca(2+)](i)) were made from arrested toad sinus venosus. sympathetic nerve stimulation activated non-alpha-, non-beta-adrenoceptors to evoke a membrane depolarization and a transient increase in [ca(2+)](i). in contrast, the beta-adrenoceptor agonist isoprenaline (10 microm) caused membrane hyperpolariza ... | 2001 | 11557570 |
| alpha2 adrenergic receptors and the central control of breathing in the cane toad, bufo marinus. | the effect of adrenergic agents on the central control of breathing in the cane toad, bufo marinus, was tested by applying adrenergic agents to the ventral medullary surface of decerebrate adult toads. toads were unidirectionally ventilated while recording lung, buccal, and artery blood pressures (bpi), as well as heart rate (hr). following a control period, filter paper pledgets soaked in the appropriate solution (epinephrine - 0.023, 0.05, 0.10, and 0.23 mm; norepinephrine - 0.002, 0.016, 0.03 ... | 2001 | 11282388 |
| involvement of cholinergic mechanisms in the central control of respiration in the cane toad, bufo marinus. | chemical substrates, central sites and central mechanisms underlying the regulation of breathing in lower vertebrates have not been well characterized. the present study was undertaken to determine the effect of ph changes and cholinergic agents on the central control of respiration in the cane toad, bufo marinus. adult toads were anesthetized, catheterized and unidirectionally ventilated before exposing the brainstem. an airtight buccal cannula was also inserted through the tympanum to record b ... | 2001 | 11282326 |
| formation and function of synapses with respect to schwann cells at the end of motor nerve terminal branches on mature amphibian (bufo marinus) muscle. | a study has been made of the formation and regression of synapses with respect to schwann cells at the ends of motor nerve terminal branches in mature toad (bufo marinus) muscle. synapse formation and regression, as inferred from the appearance and loss of n-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide (fm1-43)-stained vesicle clusters, occurred at the ends of terminal branches over a 16 hr period. multiple microelectrodes placed in an array about fm1-43 blobs at th ... | 2001 | 11264312 |
| protein synthesis in the liver of bufo marinus: cost and contribution to oxygen consumption. | while many estimates of the contribution of protein synthesis to metabolic rate exist for a variety of animals, most rely on theoretical costs of protein synthesis. the limitations of this approach are that theoretical costs depend upon variable estimates of atp cost per peptide bond. in addition, they do not take into account the fact that there are protein-specific pre- and post-translational costs. by inhibiting, protein synthesis with cycloheximide and measuring the resultant decrease in oxy ... | 1998 | 11248989 |
| short-term storage of cane toad (bufo marinus) gametes. | the responses of cane toad (bufo marinus) gametes, used as a model for the development of assisted reproduction techniques for rare and endangered amphibians, to short-term storage at temperatures > 0 degrees c were studied. whole excised testes were stored at 0 degrees or 4 degrees c for 15 days, and sperm motility was measured at excision and after storage for 2, 5, 7, 10, 12 and 15 days. spermatozoa showed > 50% motility for 7 days at 0 degrees c and for 5 days at 4 degrees c. at 15 days, onl ... | 2001 | 11226040 |
| evidence of nitric oxide and angiotensin ii regulation of circulation and cutaneous drinking in bufo marinus. | the nitric oxide synthase inhibitor n(g)-nitro-l-arginine methyl ester (l-name) increased vascular resistance (vr) 10% above baseline of 3.08+/-0.08 (n=11) mmhg/ml/min at 10 mg/kg and 20% above 3.05+/-0.08 (n=9) at 50 mg/kg in anesthetized toads (bufo marinus). blood pressure was unaffected by either dose of l-name. blood flow decreased at the higher dose of l-name. l-arginine (300 mg/kg) reversed the effects of l-name on vr and blood flow in toads treated with 10 mg/kg but not with 50 mg/kg. in ... | 2013 | 11226021 |
| intracellular calcium during fatigue of cane toad skeletal muscle in the absence of glucose. | mechanisms of fatigue were studied in single muscle fibres of the cane toad (bufo marinus) in which force, intracellular calcium ([ca2+]i), [mg2+]i, glycogen and the rapidly releasable ca2+ from the sarcoplasmic reticulum (sr) were measured. fatigue was produced by repeated tetani continued until force had fallen to 50%. two patterns of fatigue in the absence of glucose were studied. in the first fatigue run force fell to 50% in 8-10 min. fatigue runs were then repeated until force fell to 50% i ... | 2000 | 11129439 |
| aquatic and terrestrial locomotory energetics in a toad and a turtle: a search for generalisations among ectotherms. | murray short-necked turtles were trained to walk on a motorised treadmill and to swim in a recirculating flume. through filmed records, the frequency of limb movement and the time that thrust was directed against the substrate were measured. the animals wore masks when walking and accessed air when swimming from a ventilated capsule placed on top of the water surface. measurement of the exhalant o(2) and co(2) levels from these devices enabled the measurement of metabolic rates. equivalent data ... | 2006 | 11121342 |
| polymerase chain reaction primers for polymorphic microsatellite loci in the invasive toad species bufo marinus. | | 2000 | 11091334 |
| absence of evidence for isolation by distance in an expanding cane toad (bufo marinus) population: an individual-based analysis of microsatellite genotypes. | the cane toad (bufo marinus) was introduced in 1935 in australia, where it spread rapidly. we have tested for isolation by distance by analysing at a local geographical scale a continuous population using seven microsatellite markers and an individual-based method. the matrix of pairwise individual differentiation was not significantly correlated with that of geographical distance. regression analyses gave a low positive slope of 0.00072 (all individuals) or a negative slope of 0.0017 (individua ... | 2000 | 11091326 |
| hindlimb extensor muscle function during jumping and swimming in the toad (bufo marinus). | many anurans use their hindlimbs to generate propulsive forces during both jumping and swimming. to investigate the musculoskeletal dynamics and motor output underlying locomotion in such physically different environments, we examined patterns of muscle strain and activity using sonomicrometry and electromyography, respectively, during jumping and swimming in the toad bufo marinus. we measured strain and electromyographic (emg) activity in four hindlimb muscles: the semimembranosus, a hip extens ... | 2000 | 11060216 |
| potentiation by neostigmine of responses to vagal nerve stimulation in the sinus venosus of the toad. | the effects of the cholinesterase inhibitor neostigmine on the responses to vagus nerve stimulation of isolated sinus venosus/atrial preparations of the toad, bufo marinus, were examined. in control solutions, trains of stimuli applied to the vagus nerve led to a decrease in heart rate that was susceptible to muscarinic receptor blockade. membrane potential recordings made from sinus venosus cells showed that the responses to trains of stimuli, delivered at frequencies of less than 10 hz, were l ... | 2000 | 11023616 |
| the mechanisms of sarcoplasmic reticulum ca2+ release in toad pacemaker cells. | the mechanisms of sarcoplasmic reticulum (sr) ca2+ release in pacemaker cells from the sinus venosus of the cane toad (bufo marinus) were studied. single, isolated cells were voltage clamped using a nystatin-perforated patch. ionic currents and intracellular ca2+ concentration ([ca2+]i) were recorded simultaneously. depolarizations of 300 ms duration from a holding potential of -55 mv produced an inward current which had a bell-shaped relationship with voltage. inward current first appeared at a ... | 2000 | 10856122 |
| pulmonary vagal modulation of ventilation in toads (bufo marinus). | this study examined the role of pulmonary vagal feedback on hypercapnic chemosensitivity and breathing pattern formation in cane toads (bufo marinus). decerebrate, paralysed toads were uni-directionally ventilated with air, 2.5% co(2) or 5.0% co(2) with the lungs inflated or deflated, before and after pulmonary vagotomy. motor output from the mandibular branch of the trigeminal nerve served as an index of fictive breathing. as respiratory drive was increased, breathing frequency increased and br ... | 2000 | 10828339 |
| mitochondrial ca2+ homeostasis during ca2+ influx and ca2+ release in gastric myocytes from bufo marinus. | 1. the ca(2+)-sensitive fluorescent indicator rhod-2 was used to monitor mitochondrial ca2+ concentration ([ca2+]m) in gastric smooth muscle cells from bufo marinus. in some studies, fura-2 was used in combination with rhod-2, allowing simultaneous measurement of cytoplasmic ca2+ concentration ([ca2+]i) and [ca2+]m, respectively. 2. during a short train of depolarizations, which causes ca2+ influx from the extracellular medium, there was an increase in both [ca2+]i and [ca2+]m. the half-time (t1 ... | 2000 | 10713963 |
| ca(2+) channel-mediated currents in retinal glial (müller) cells of the toad (bufo marinus). | whole-cell voltage-clamp recordings were used to detect voltage-gated ca(2+) channels in freshly isolated retinal glial (müller) cells of the toad (bufo marinus). using ca(2+) ions (2 mm) as charge carriers (in the presence of 1 mm mg(2+)), no inwardly directed currents could be observed during the application of depolarizing voltage steps. however, after omitting the divalent cations from the bath solution, large-amplitude inwardly directed currents were evoked that were carried by na(+) ions, ... | 2000 | 10704766 |
| responses of single neurons in the toad's caudal ventral striatum to moving visual stimuli and test of their efferent projection by extracellular antidromic stimulation/recording techniques. | previous work in anuran amphibians has shown that activity in the caudal ventral striatum correlates with visuomotor activity: orienting responses toward prey fail to occur after striatal lesions. thus it has been suggested that the striatum influences visually guided behavior. therefore, the present study investigates visual response properties from neurons recorded in the striatum. extracellular recordings of 104 single neurons of the cane toad's (bufo marinus) caudal ventral striatum (str) re ... | 1999 | 10681604 |
| an electrophoretic study of myosin heavy chain expression in skeletal muscles of the toad bufo marinus. | in this study we developed an sds-page protocol which for the first time separates effectively all myosin heavy chain (mhc) isoforms expected to be expressed in iliofibularis (if), pyriformis (pyr), cruralis (cru) and sartorius (sar) muscles of the toad bufo marinus on the basis of previously reported fibre type composition. the main feature of the method is the use of alanine instead of glycine both in the separating gel and in the running buffer. the correlation between the mhc isoform composi ... | 1999 | 10672517 |
| lung deflation stimulates fictive ventilation in decerebrated and unidirectionally ventilated toads. | we describe how the degree of lung inflation and hypercapnia influenced fictive ventilation in five toads (bufo marinus) that were decerebrated and paralysed with roccuronium. both lungs were unidirectionally ventilated and the degree of lung inflation was determined by controlling the outflow resistance of these catheters, while ventilatory motor output was assessed on the basis of nervous activity in the mandibular branch of the vth cranial nerve. the pattern of the recorded activity ('fictive ... | 1999 | 10647862 |
| surfactant in the gas mantle of the snail helix aspersa. | surfactant occurs in cyclically inflating and deflating, gas-holding structures of vertebrates to reduce the surface tension of the inner fluid lining, thereby preventing collapse and decreasing the work of inflation. here we determined the presence of surfactant in material lavaged from the airspace in the gas mantle of the pulmonate snail helix aspersa. surfactant is characterized by the presence of disaturated phospholipid (dsp), especially disaturated phosphatidylcholine (pc), lavaged from t ... | 2006 | 10603332 |
| salt sensitivity and hydration behavior of the toad, bufo marinus. | toads, bufo marinus, were placed on laboratory tissue saturated with water or with hyperosmotic (250 or 500 mm nacl or kcl) solutions, and their behavior was observed for 5 min. toads placed on water initially allowed their ventral skin to touch the surface without abducting the hind limbs. during this "seat patch down" (spd) behavior toads appeared to be evaluating the suitability of a hydration source prior to initiating "water absorption response" (wr) behavior with the hind limbs fully abduc ... | 1999 | 10604846 |
| large retinal ganglion cells that form independent, regular mosaics in the bufonoid frogs bufo marinus and litoria moorei. | population-based methods were used to study labeled retinal ganglion cells from the cane toad bufo marinus and the treefrog litoria moorei, two visually competent bufonoid neobatrachians with contrasting habitats. in both, cells with large somata and thick dendrites formed distinct types with independent mosaics. the alpha(a), alpha(ab), and alpha(c) mosaics of bufo in all major respects resembled those of ranids, studied previously, and could be provisionally matched to the same functional clas ... | 2006 | 10580722 |
| cardiorespiratory responses of the toad (bufo marinus) to hypoxia at two different temperatures. | central vascular blood flows and ventilation were measured in conscious toads (bufo marinus) at 15 and 25 degrees c. the animals were exposed to hypoxia (fi(o)(sum)=0.10 and 0.05, where fi(o)(sum) is the fractional oxygen concentration of inspired air) at both temperatures. in addition, the cardiorespiratory responses to hypercapnia (fi(co)(sum)=0.05) and atropine injection (5 mg kg(-)(1); 7.4 micromol kg(-)(1)) were studied at 25 degrees c. at 25 degrees c, systemic blood flow ( q_dot (sys)) ex ... | 1999 | 10574742 |
| effects of temperature and physical activity on blood flow shunts and intracardiac mixing in the toad bufo marinus. | blood flow in systemic (.qsys) and pulmocutaneous (.qpul) arteries was measured as a function of body temperature (10 degrees, 20 degrees, and 30 degrees c) at rest and following enforced physical activity in conscious, adult cane toads (bufo marinus). arterial and mixed venous hemoglobin concentration (chb) and total oxygen content (co2, tot) were measured in a separate group under identical conditions. heart rate (fh) and total flow (.qtot) increased significantly (p<0.001) with elevated tempe ... | 2013 | 10521319 |
| vesicle-associated proteins and quantal release at single active zones of amphibian (bufo marinus) motor-nerve terminals. | a study was made to determine the disposition of vesicle-associated proteins (syntaxin, sv2, snap-25) and calcium channels with respect to the spatial extent of spontaneous and evoked quantal release within regions of amphibian motor-nerve terminal branches delineated by fm1-43 stained vesicle clusters (blobs). discrete concentrations of vesicles revealed approximately 2 microm apart along the length of terminal branches through fm1-43 staining were identical in size and spacing to those identif ... | 1999 | 10482733 |
| erratum: everett a.w. 1999. membrane recycling due to low and high rates of nerve stimulation at release sites in the amphibian (bufo marinus) neuromuscular junction. synapse 32:110-118. | erratum: everett a.w. 1999. membrane recycling due to low and high rates of nerve stimulation at release sites in the amphibian (bufo marinus) neuromuscular junction. synapse 32:110-118. in the above-referenced article, figure 1 was erroneously reproduced in black and white as converted from a color original, not providing an accurate representation of the staining. the figure is reproduced here as the author intended, from an original black and white rendering. the publisher sincerely apologize ... | 1999 | 10459175 |
| glycogen content and excitation-contraction coupling in mechanically skinned muscle fibres of the cane toad. | 1. mechanically skinned skeletal muscle fibres from the twitch region of the iliofibularis muscle of cane toads were used to investigate the relationship between fibre glycogen content and fibre capacity to respond to transverse tubular (t-) system depolarization. 2. a large proportion of total fibre glycogen remained in mechanically skinned muscle fibres exposed to aqueous solutions. this glycogen pool (about 80% of total fibre glycogen) was very stable when the preparation was incubated in a r ... | 1999 | 10432348 |
| the role of calcium stores in fatigue of isolated single muscle fibres from the cane toad. | 1. intracellular calcium ([ca2+]i) and tension were measured from single muscle fibres dissected from the cane toad (bufo marinus). the amount of ca2+ which could be released from the sarcoplasmic reticulum (sr) was estimated by brief (approximately 20 s) exposures to 4-chloro-m-cresol (4-cmc) or caffeine. 2. muscle fatigue was produced by repeated tetani at 4 s or shorter intervals and continued until tension had fallen to 50% of the control. the intracellular free calcium concentration during ... | 1999 | 10432347 |