Genetic variation in the cellular response of Daphnia magna (Crustacea: Cladocera) to its bacterial parasite

Stuart K. J. R. Auld, Jennifer A. Scholefield, Tom J. Little

Research output: Contribution to journalArticlepeer-review

Abstract

Linking measures of immune function with infection, and ultimately, host and parasite fitness is a major goal in the field of ecological immunology. In this study, we tested for the presence and timing of a cellular immune response in the crustacean Daphnia magna following exposure to its sterilizing endoparasite Pasteuria ramosa. We found that D. magna possesses two cell types circulating in the haemolymph: a spherical one, which we call a granulocyte and an irregular-shaped amoeboid cell first described by Metchnikoff over 125 years ago. Daphnia magna mounts a strong cellular response (of the amoeboid cells) just a few hours after parasite exposure. We further tested for, and found, considerable genetic variation for the magnitude of this cellular response. These data fostered a heuristic model of resistance in this naturally coevolving host-parasite interaction. Specifically, the strongest cellular responses were found in the most susceptible hosts, indicating resistance is not always borne from a response that destroys invading parasites, but rather stems from mechanisms that prevent their initial entry. Thus, D. magna may have a two-stage defence-a genetically determined barrier to parasite establishment and a cellular response once establishment has begun.

Original languageEnglish
Pages (from-to)3291-3297
Number of pages7
JournalProceedings of the Royal Society B-Biological Sciences
Volume277
Issue number1698
DOIs
Publication statusPublished - 7 Nov 2010

Keywords

  • invertebrate immunity
  • haemocytes
  • host-parasite coevolution
  • resistance
  • Daphnia, Pasteuria
  • BY-ENVIRONMENT INTERACTIONS
  • PASTEURIA-PENETRANS
  • PHENOLOXIDASE ACTIVITY
  • IMMUNE-RESPONSES
  • HOST-PARASITE
  • FRESH-WATER
  • RESISTANCE
  • POPULATION
  • DROSOPHILA
  • INFECTION

Cite this