| the relationship between pseudodiplorchis americanus (monogenea) density and host resources under controlled environmental conditions. | a previous study has shown that, under natural conditions, energy reserves of the desert toad, scaphiopus couchii, are negatively related to the density of infection by pseudodiplorchis americanus. however, this was based predominantly on collections of active animals from breeding congregations and inevitably selected toads which were in good condition. the parasite, a blood-feeding monogenean, occurs in burdens of up to 30 worms/host (mean intensity 6 worms/host) and represents a significant d ... | 1994 | 8159463 |
| survival of pseudodiplorchis americanus (monogenea) under controlled environmental conditions. | populations of pseudodiplorchis americanus infecting the desert toad, scaphiopus couchii, have previously been shown to be remarkably stable from year to year, despite wide variation in conditions promoting invasion. the present study aimed to document the survival of both first-year and pre-existing adults under controlled laboratory temperatures. first-year worm survival in experimentally infected toads was shown to be very high for the first 5 months after migration to the definitive site, an ... | 1994 | 8159464 |
| parasitic disease in amphibians: control by the regulation of worm burdens. | this review considers three case studies based on macroparasites of anurans: (a) natural infections in the permanently-aquatic xenopus laevis which represent the worm burdens acquired, and the implications for pathology, when hosts are exposed to continuous, year-round, transmission; (b) the desert toad, scaphiopus couchii, which experiences invasion very briefly each year and provides a simplified system involving only a single significant infection (pseudodiplorchis americanus); (c) the mesic ... | 1995 | 8632921 |
| histological analysis of the egg capsule of the ovoviviparous polystomatid monogenean, pseudodiplorchis americanus. | transmission of pseudodiplorchis americanus is restricted to the brief period when its host, a desert toad, enters water to spawn. the parasite accumulates its entire annual reproductive output within an elongated uterus during the 10-11-month period of host hibernation. embryos of p. americanus, at all stages of development, are retained within the uterus which eventually becomes packed with around 150 encapsulated infective larvae. recently formed eggs, which comprise a fertilized ovum and 2-3 ... | 1997 | 9363490 |
| parasite adaptation to extreme conditions in a desert environment. | deserts represent universally recognized extreme environments for animal life. this paper documents the highly specialized adaptations of pseudodiplorchis americanus, a monogenean parasite of the desert toad, scaphiopus couchii. building on a long-term record of parasite population ecology (continuing since the early 1980s), field studies focus on the effects of severe drought in the sonoran desert, arizona, in the mid 1990s. this provides a test of the ability of the host-parasite system to tol ... | 1999 | 11254147 |
| host factors limiting monogenean infections: a case study. | comprehensive field data on polystomatid monogeneans record low prevalence and intensity of infection and suggest that worm burdens in this group are strongly regulated: thus, in the majority of polystoma species infecting anuran amphibians mean abundance is typically less than one parasite/host. there is circumstantial evidence that the dominant control is attributable to host factors which over-ride variations in transmission success. this review provides a brief summary of information on pseu ... | 2002 | 11835975 |
| pathological effects of pseudodiplorchis americanus (monogenea: polystomatidae) on the lung epithelium of its host, scaphiopus couchii. | infection of the desert toad, scaphiopus couchii, by the monogenean pseudodiplorchis americanus involves 2 principal sites: post-invasion juveniles reside in the respiratory tract for 1 month before migrating to the urinary bladder where they reach sexual maturity and may live up to 4 years. while previous work has demonstrated the long-term impact on host condition of the blood-feeding adults, this study assesses pathological effects of the short-term pulmonary infection. lung ultrastructure wa ... | 2002 | 12211607 |
| complete mitochondrial genome of the desert toad-headed agama, phrynocephalus przewalskii (reptilia, squamata, agamidae), a novel gene organization in vertebrate mtdna. | the mitogenome of the desert toad-headed agama, phrynocephalus przewalskii, was amplified using polymerase chain reaction (pcr), long-and-accurate pcr and directly sequenced by primer walking. the complete mitogenome was 16,892 bp in size and contained 13 protein-coding, 23 trna, and 2 rrna genes, and 1 control region. the mitogenome of the p. przewalskii was similar to those of other phrynocephalus sand lizards in gene arrangement and composition, except that trna-phe and trna-pro were exchange ... | 2015 | 24117191 |
| a multilocus perspective on the speciation history of a north american aridland toad (anaxyrus punctatus). | interpretations of phylogeographic patterns can change when analyses shift from single gene-tree to multilocus coalescent analyses. using multilocus coalescent approaches, a species tree and divergence times can be estimated from a set of gene trees while accounting for gene-tree stochasticity. we utilized the conceptual strengths of a multilocus coalescent approach coupled with complete range-wide sampling to examine the speciation history of a broadly distributed, north american warm-desert to ... | 2012 | 22579923 |
| localization of water channels in the skin of two species of desert toads, anaxyrus (bufo) punctatus and incilius (bufo) alvarius. | anuran amphibians obtain water by osmosis across their ventral skin. a specialized region in the pelvic skin of semiterrestrial species, termed the seat patch, contains aquaporins (aqps) that become inserted into the apical plasma membrane of the epidermis following stimulation by arginine vasotocin (avt) to facilitate rehydration. two avt-stimulated aqps, aqp-h2 and aqp-h3, have been identified in the epidermis of seat patch skin of the japanese tree frog, hyla japonica, and show a high degree ... | 2011 | 21882955 |
| plasma and brain angiotensin concentrations associated with water response behavior in the desert anuran, scaphiopus couchii under natural conditions in the field. | terrestrial amphibians obtain water by absorption across a specialized region of the ventral skin and exhibit a behavior, the water absorption response (wr) to place that region in contact with moist surfaces. spadefoot toads (scaphiopus couchii) spend dry months of the year in burrows, then emerge during brief periods of summer rainfall and seek water sources for rehydration and reproduction. we tested the hypothesis that these toads have changes in plasma and/or central angiotensin concentrati ... | 2010 | 20708705 |
| the spinal nerves innervate putative chemosensory cells in the ventral skin of desert toads, bufo alvarius. | toads normally obtain water by absorption across their skin from osmotically dilute sources. when hyperosmotic salt solutions are presented as a hydration source to dehydrated desert toads, they place the ventral skin onto the source but soon afterwards escape to avoid dehydration. the escape behavior coincides with neural excitation of the spinal nerves that innervate putative chemosensory cells in the ventral skin. in the present study, fluorescent dye translocated through the spinal nerves to ... | 2001 | 11396713 |
| desert toads discriminate salt taste with chemosensory function of the ventral skin. | toads obtain water by absorption across their skin. when dehydrated, desert toads exhibit stereotyped hydration behavior in which they press their ventral skin onto a moist surface. however, dehydrated toads avoid surfaces moistened with hyperosmotic nacl and kcl solutions (hoff kvs, hillyard sd. 1993. j. exp. biol. 183:347-351). we have studied neural mechanisms for this avoidance with physiologic, behavioral, and morphologic approaches. spinal nerves innervating the ventral skin could be stimu ... | 1999 | 10331584 |
| bufo alvarius: a potent hallucinogen of animal origin. | anthropologists have long speculated that ancient peoples of mesoameria used a toad, bufo marinus, as a ritual intoxicant. this hypothesis rests on many iconographic and mythological representations of toads and on a number of speculative ethnographic reports. the authors reject b. marinus as a candidate for such use because of the toxicity of its venom. a more likely candidate is the sonoran desert toad, bufo alvarius, which secretes large amounts of the potent known hallucinogen, 5-methoxy-n,n ... | 1994 | 8170151 |
| effects of density and predation on scaphiopus couchi tadpoles in desert ponds. | the effects of density on growth and development of scaphiopus couchi tadpoles in desert ponds were investigated, and sources of mortality over a three-year period were documented. in 16 of the 82 ponds monitored, predation was the principal cause of death, demonstrating that tadpoles in desert ponds may be exposed to high levels of predation, although the overall importance of predation is less here than in more mesic areas. desiccation was the primary cause of mortality in 49 ponds. growth and ... | 1987 | 28312260 |
| rate of water uptake through the integument of the desert toad, bufo punctatus. | | 1969 | 5777385 |