• Login
    View Item 
    •   Home
    • Events
    • WEP Library ePoster competition 2019
    • View Item
    •   Home
    • Events
    • WEP Library ePoster competition 2019
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of KAUSTCommunitiesIssue DateSubmit DateThis CollectionIssue DateSubmit Date

    My Account

    Login

    Quick Links

    Open Access PolicyORCID LibguidePlumX LibguideSubmit an Item

    Statistics

    Display statistics

    THE IMPORTANCE OF OSMO-MIXOTROPHY IN THE NUTRITION OF THE DIATOM THALASSIOSIRA OCEANICA UNDER IRON LIMITATION

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    P23.pdf
    Size:
    980.5Kb
    Format:
    PDF
    Download
    Type
    Poster
    Authors
    Alothman, Afrah
    Date
    2019-01-13
    Permanent link to this record
    http://hdl.handle.net/10754/655729
    
    Metadata
    Show full item record
    Abstract
    The Importance of Osmo-mixotrophy in the Nutrition of the Diatom ThalassiosiraoceanicaUnder Iron Limitation Afrah Alothman, MSc thesis, Biology Department at Dalhousie University, Halifax, NS, Canada (July 2017). © Copyright by Afrah Alothman, 2017 Introduction: In general, photosynthetic carbon fixation by phytoplankton contributes significantly to carbon sequestration and storage in the deep ocean through the biological pump (Martin, 1990). Martin (1990) put forward the “iron hypothesis” that the rapid changes in CO2concentration in the atmosphere observed on geological timescales could be due to low phytoplankton productivity caused by iron deficiency in the HNLC regions. Diatoms such as Thalassiosira oceanica arevery plastic in their physiology and can acclimate to nutrient-limited conditions by down-regulating specific physiological processes in order to minimize demands for certain elements or nutrients, including iron (Lommer et al., 2012 & Chappell et al, 2015). This thesis aims to study the ‘osmo-mixotrophy’ defined as the utilization of organic substrates available in the environment(labile organic substrates) (Selosseet al, 2016) by autotrophic organism T. oceanica under iron replete and iron limited condition. Method: The isotope labelling experiments were designed to measure the uptake and the assimilation of inorganic (CO2) and organic carbon and nitrogen (Urea) by cells grown in iron-replete and iron-limited conditions incubated with either15N-nitrateor13C/15N-ureaas inorganic nitrogen and organic nitrogen source, respectively. Throughout the growth period, a series of physiological measurements were conducted (Table 1), and when the cells reach the exponential growth phase, cultures were harvested for incubating the isotope labelling samples(ILE). Results: 1- Thalassiosira oceanicacan grow osmo-mixotrophically (Figure 2, Figure 3). 2- Urea as an organic nitrogen and carbon source supported higher biomass than nitrate under iron limited condition(Figure 4) 3- Both C and N atoms from urea are assimilated by T. oceanica(Table 2). Conclusion Isotope labeling experiments with 13C-HCO3onate,15N-nitrate, and dual labeled 13C/15N urea showed that both N and C from the urea molecule were assimilated into cellular biomass by T. oceanica, though C uptake was at a lower rate than photosynthetic CO2fixation; the C/N uptake ratio was 0.15, which is less than the 0.5 C/N stoichiometric ratio of the urea molecule. In addition, the C uptake from urea under iron-limited and iron-replete conditions contributed from 5% ± 3.72to 11% ± 1.71 of total carbon assimilation. This was proportional to the fraction of urea-C relative to the total pool of dissolved carbon in the medium. In addition, the batch culture experiments suggested that, at equal dissolved N concentrations, urea supported a higher biomass than nitrate in iron-limited cultures. There was no significant difference in photosynthetic carbon fixation and nutrient uptake between the iron-limited and the iron-replete cultures. References: Chappell, P. D., Whitney, L. P., Wallace, J. R., Darer, A. I., Jean-Charles, S., & Jenkins, B. D. (2015). Genetic indicators of iron limitation in wild populations of Thalassiosira oceanicafrom the northeast Pacific Ocean. The ISME journal, 9(3), 592-602. Lommer, M., Specht, M., Roy, A. S., Kraemer, L., Andreson, R.,Gutowska, M. A., &LaRoche, J. (2012). Genome and low-iron response of an oceanic diatom adapted to chronic iron limitation. Genome biology, 13(7), R66. Martin, J. H. (1990). Glacial‐interglacial CO2 change: The iron hypothesis. Paleoceanography,5(1), 1-13.‏ Selosse, M. A., Charpin, M., & Not, F. (2016). Mixotrophyeverywhere on land and in water: the grand écarthypothesis. Ecology Letters.
    Conference/Event name
    WEP Library ePoster competition 2019
    Additional Links
    https://epostersonline.com/wep2019/node/127
    Collections
    WEP Library ePoster competition 2019; Posters

    entitlement

     
    DSpace software copyright © 2002-2021  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service hosted by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items. For anonymous users the allowed maximum amount is 50 search results.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.