Cardiac adaptations of bullfrog tadpoles in response to chytrid infection

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Salla, Raquel Fernanda ; Gamero, Fernando Urban ; Ribeiro, Larissa Rodrigues ; Rizzi, Gisele Miglioranza ; Dal Medico, Samuel Espinosa ; Rissoli, Rafael Zanelli ; Vieira, Conrado Augusto ; Mathias Silva-zacarin, Elaine Cristina ; Leite, Domingos Silva ; Abdalla, Fabio Camargo ; Toledo, Luis Felipe ; Costa, Monica Jones

• Document type: Journal article
• Source: OURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL AND INTEGRATIVE PHYSIOLOG; v. 323, n. 7, p. 10-pg., 2015-08-01.

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. J. Exp. Zool. 323A: 487-496, 2015. (c) 2015 Wiley Periodicals, Inc. (AU)

• FAPESP's process: 08/57712-4 - The National Institute of Comparative Physiological Research
• Grantee: Augusto Shinya Abe
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 11/51694-7 - Into the heart of an epidemic: a US-Brazil collaboration for integrative studies of the amphibian-killing fungus in Brazil
• Grantee: Luis Felipe de Toledo Ramos Pereira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/06632-3 - Effects of the infection by the Batrachochytrium dendrobatidis on the cardiac morphophysiology of bullfrog tadpoles
• Grantee: Raquel Fernanda Salla Jacob
• Support Opportunities: Scholarships in Brazil - Scientific Initiation