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Michelle Neudeck thesis.pdf (1.91 MB)

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Tolerance of Planktothrix agardhii to nitrogen depletion

Neudeck, Michelle Joan
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1522329471601801

Abstract Details

2018, Master of Science (MS), Bowling Green State University, Biological Sciences.
Sandusky Bay is plagued by recurrent cyanobacterial harmful algal blooms (cHABs). A persistent bloom occurred in 2015 from June into October even though the levels of nitrogen dropped to near undetectable levels due to high rates of both assimilatory and dissimilatory nitrate reduction. Planktothrix agardhii is the main organism of the cHABs despite being non-diazotrophic. This cyanobacterium produces microcystin, a hepatotoxin. The Sandusky Bay waters were sampled every two weeks. RNA was extracted from the samples and sequenced. The metatranscriptomes were analyzed for genes pertaining to nitrogen storage and retrieval. P. agardhii stores N as cyanophycin, a polymer of arginine and aspartic acid. This is produced by cyanophycin synthetase which is encoded by cphA. P. agardhii has two paralogs of this gene. cphA is associated with cphB, the gene that encodes cyanophycinase that hydrolyzes cyanophycin into arginine-aspartic acid dimers. cphA' is monocistronic. N was replete from June until mid-July, while the discharge of the Sandusky River was high, cphA' was transcribed at this time. When the N levels dropped to 0, cphB and cphA were transcribed. Degradation of the phycobilisome is another source of N that can be scavenged by P. agardhii. A small protein that triggers the degradation of the phycobilisome is encoded by nblA. The transcripts from P. agardhii demonstrated that nblA was not transcribed until after cphB was transcribed. This indicated that P. agardhii utilized the N stores of cyanophycin before utilizing the N sequestered in the phycobilisome. The Sandusky Bay was turbid throughout the sampling season which is ideal for low light tolerant Planktothrix. The transcripts of hliA, which encodes for a protein that protects the photosynthetic apparatus from oxidative damage, was almost continuously present in the samples.
George Bullerjahn, Ph.D (Advisor)
R. Michael McKay, Ph.D (Committee Member)
Paul Morris, Ph.D (Committee Member)
47 p.
Biology; Microbiology
cyanophycin; phycobilisome; Planktothrix agardhii; nitrogen stress; highlight stress

Recommended Citations

Citations

  • Neudeck, M. J. (2018). Tolerance of Planktothrix agardhii to nitrogen depletion [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1522329471601801

    APA Style (7th edition)

  • Neudeck, Michelle. Tolerance of Planktothrix agardhii to nitrogen depletion. 2018. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1522329471601801.

    MLA Style (8th edition)

  • Neudeck, Michelle. "Tolerance of Planktothrix agardhii to nitrogen depletion." Master's thesis, Bowling Green State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1522329471601801

    Chicago Manual of Style (17th edition)

bgsu1522329471601801
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This open access ETD is published by Bowling Green State University and OhioLINK.