Details:

Journal Title:
Applied and Environmental Microbiology
Personal Author:
Harke, Matthew J. ; Jankowiak, Jennifer G. ; Morrell, Brooke K. ; Gobler, Christopher J.
Harke, Matthew J. ; Jankowiak, Jennifer G. ; Morrell, Brooke K. ; Gobler, Christopher J. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research)
Description:
The bloom-forming, toxic cyanobacterium Microcystis synthesizes multiple secondary metabolites and has been shown to deter zooplankton grazing. However, the biochemical and/or molecular basis by which Microcystis deters zooplankton remains unclear. This global transcriptomic study explored the response of Microcystis to direct and indirect exposures to multiple densities of two cladoceran grazers, Daphnia pulex and D. magna . Higher densities of both daphnids significantly reduced Microcystis cell densities and elicited a stronger transcriptional response in Microcystis . While many putative grazer deterrence genes (encoding microcystin, aeruginosin, cyanopeptolin, and microviridin) were largely unaffected by zooplankton, transcripts for heat shock proteins ( hsp ) increased in abundance. Beyond metabolites and hsp , large increases in the abundances of transcripts from photosynthetic processes were observed, evidencing energy acquisition pathways were stimulated by grazing. In addition, transcripts of genes associated with the production of extracellular polysaccharides and gas vesicles significantly increased in abundance. These genes have been associated with colony formation and may have been invoked to deter grazers. Collectively, this study demonstrates that daphnid grazers induce a significant transcriptomic response in Microcystis , suggesting this cyanobacterium upregulates specific biochemical pathways to adapt to predation. IMPORTANCE This work explores the transcriptomic responses of Microcystis aeruginosa following exposure to grazing by two cladocerans, Daphnia magna and D. pulex . Contrary to previous hypotheses, Microcystis did not employ putative grazing deterrent secondary metabolites in response to the cladocerans, suggesting they may have other roles within the cell, such as oxidative stress protection. The transcriptional metabolic signature during intense grazing was largely reflective of a growth and stress response, although increasing abundances of transcripts encoding extracellular polysaccharides and gas vesicles were potentially related to predator avoidance.
Keywords:
[+]
Applied Microbiology And Biotechnology Biotechnology Ecology Food Science
Source:
Applied and Environmental Microbiology, 83(5)
DOI:
https://doi.org/10.1128/aem.02832-16
ISSN:
0099-2240;1098-5336;
Format:
PDF
Publisher:
American Society for Microbiology
Document Type:
Journal Article
Funding:
Grant no. NA10NOS4780140
License:
https://creativecommons.org/licenses/by/4.0/
Rights Information:
CC BY
Compliance:
Library
Main Document Checksum:
[+]
urn:sha256:9c58cc76b65cced66012573f3551f9e79a83d5692e7a1ad76f7ecbab367e6fe9
Download URL:
https://repository.library.noaa.gov/view/noaa/58863/noaa_58863_DS1.pdf
File Type:

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