title: Cardiac adaptations of bullfrog tadpoles in response to chytrid infection.
abstract: The chytrid fungus Batrachochytrium dendrobatidis (Bd) can result in heart failure in Bd-susceptible species. Since Bd infection generally does not cause mortality in North American bullfrogs, the aim of this work was to verify whether this species presents any cardiac adaptation that could improve the tolerance to the fungus. Thus, we analyzed tadpoles' activity level, relative ventricular mass, ventricle morphology, in loco heart frequency, and in vitro cardiac function. The results indicate that infected animals present an increase in both ventricular relative mass and in myofibrils' incidence, which accompanied the increase in myocytes' diameter. Such morphological alterations enabled an increase in the in vitro twitch force that, in vivo, would result in elevation of the cardiac stroke volume. This response requires much less energy expenditure than an elevation in heart frequency, but still enables the heart to pump a higher volume of blood per minute (i.e., an increase in cardiac output). As a consequence, the energy saved in the regulation of the cardiac function of Bd-infected tadpoles can be employed in other homeostatic adjustments to avoid the lethal effect of the fungus. Whether other species present this ability, and to what extent, remains uncertain, but such possible interspecific variability might explain different mortality rates among different species of Bd-infected amphibians.
authors.affiliation: Laboratory of Conservation Physiology, Department of Biology, Federal University of S, ã, o Carlos (UFSCar), Sorocaba, São Paulo, Brazil.
authors.forename: Raquel Fernanda
authors.initials: RF
authors.lastname: Salla
authors.affiliation: Laboratory of Conservation Physiology, Department of Biology, Federal University of S, ã, o Carlos (UFSCar), Sorocaba, São Paulo, Brazil.
authors.forename: Fernando Urban
authors.initials: FU
authors.lastname: Gamero
authors.affiliation: Laboratory of Conservation Physiology, Department of Biology, Federal University of S, ã, o Carlos (UFSCar), Sorocaba, São Paulo, Brazil.
authors.forename: Larissa Rodrigues
authors.initials: LR
authors.lastname: Ribeiro
authors.affiliation: Laboratory of Structural and Functional Biology, Department of Biology, Federal University of São Carlos (UFSCar), Sorocaba, São Paulo, Brazil.
authors.forename: Gisele Miglioranza
authors.initials: GM
authors.lastname: Rizzi
authors.affiliation: Laboratory of Conservation Physiology, Department of Biology, Federal University of S, ã, o Carlos (UFSCar), Sorocaba, São Paulo, Brazil.
authors.forename: Samuel Espinosa Dal
authors.initials: SE
authors.lastname: Medico
authors.affiliation: Laboratory Zoophysiology and Comparative Biochemistry (LZBC), Department of Physiological Sciences. Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil.
authors.forename: Rafael Zanelli
authors.initials: RZ
authors.lastname: Rissoli
authors.affiliation: Laboratory of Natural History of Brazilian Amphibians (LaHNAB), Department of Animal Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
authors.forename: Conrado Augusto
authors.initials: CA
authors.lastname: Vieira
authors.affiliation: Laboratory of Structural and Functional Biology, Department of Biology, Federal University of São Carlos (UFSCar), Sorocaba, São Paulo, Brazil.
authors.forename: Elaine Cristina Mathias
authors.initials: EC
authors.lastname: Silva-Zacarin
authors.affiliation: Laboratory of Bacterial Antigens II, Department of Genetics, Evolution and Bioagents, Institute of Biology, Department of Zoology Museum "Prof. Adão José Cardoso", State University of Campinas, Campinas (UNICAMP), Brazil.
authors.forename: Domingos Silva
authors.initials: DS
authors.lastname: Leite
authors.affiliation: Laboratory of Structural and Functional Biology, Department of Biology, Federal University of São Carlos (UFSCar), Sorocaba, São Paulo, Brazil.
authors.forename: Fábio Camargo
authors.initials: FC
authors.lastname: Abdalla
authors.affiliation: Laboratory of Bacterial Antigens II, Department of Genetics, Evolution and Bioagents, Institute of Biology, Department of Zoology Museum "Prof. Adão José Cardoso", State University of Campinas, Campinas (UNICAMP), Brazil.
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Toledo
authors.affiliation: Laboratory of Conservation Physiology, Department of Biology, Federal University of S, ã, o Carlos (UFSCar), Sorocaba, São Paulo, Brazil.
authors.forename: Monica Jones
authors.initials: MJ
authors.lastname: Costa
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002302:Cardiac Output; D008411:Chytridiomycota / Q000502:physiology; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D006352:Heart Ventricles; D007814:Larva / Q000382:microbiology / Q000502:physiology; D011892:Rana catesbeiana / Q000382:microbiology / Q000502:physiology*; D013318:Stroke Volume