Physiological ecology - Original Paper

Oecologia

, Volume 169, Issue 1, pp 23-31

Dietary protein restriction impairs growth, immunity, and disease resistance in southern leopard frog tadpoles

  • Matthew D. VeneskyAffiliated withDepartment of Biological Sciences, The University of MemphisDepartment of Integrative Biology, The University of South Florida Email author 
  • , Travis E. WilcoxenAffiliated withDepartment of Biological Sciences, The University of MemphisDepartment of Biology, Milikin University
  • , Michelle A. RenselAffiliated withDepartment of Biological Sciences, The University of MemphisDepartment of Integrative Biology and Physiology, University of California, Los Angeles
  • , Louise Rollins-SmithAffiliated withDepartments of Microbiology and Immunology, Pediatrics, and Biological Sciences, Vanderbilt University Medical Center
  • , Jacob L. KerbyAffiliated withDepartment of Biology, University of South Dakota
  • , Matthew J. ParrisAffiliated withDepartment of Biological Sciences, The University of Memphis

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Abstract

The immune system is a necessary, but potentially costly, defense against infectious diseases. When nutrition is limited, immune activity may consume a significant amount of an organism’s energy budget. Levels of dietary protein affect immune system function; high levels can enhance disease resistance. We exposed southern leopard frog [Lithobates sphenocephalus (=Rana sphenocephala)] tadpoles to high and low protein diets crossed with the presence or absence of the pathogenic amphibian chytrid fungus (Batrachochytrium dendrobatidis; Bd) and quantified: (1) tadpole resistance to Bd; (2) tadpole skin-swelling in response to phytohaemagglutinin (PHA) injection (a measure of the T cell-mediated response of the immune system); (3) bacterial killing ability (BKA) of tadpole blood (a measure of the complement-mediated cytotoxicity of the innate immune system); and (4) tadpole growth and development. Tadpoles raised on a low-protein diet were smaller and less developed than tadpoles on a high-protein diet. When controlled for developmental stage, tadpoles raised on a low-protein diet had reduced PHA and BKA responses relative to tadpoles on a high-protein diet, but these immune responses were independent of Bd exposure. High dietary protein significantly increased resistance to Bd. Our results support the general hypothesis that host condition can strongly affect disease resistance; in particular, fluctuations in dietary protein availability may change how diseases affect populations in the field.

Keywords

Batrachochytrium dendrobatidis BKA Chytridiomycosis Nutrition PHA