title: Genetic indicators of iron limitation in wild populations of Thalassiosira oceanica from the northeast Pacific Ocean.
abstract: Assessing the iron (Fe) nutritional status of natural diatom populations has proven challenging as physiological and molecular responses can differ in diatoms of the same genus. We evaluated expression of genes encoding flavodoxin (FLDA1) and an Fe-starvation induced protein (ISIP3) as indicators of Fe limitation in the marine diatom Thalassiosira oceanica. The specificity of the response to Fe limitation was tested in cultures grown under Fe- and macronutrient-deficient conditions, as well as throughout the diurnal light cycle. Both genes showed a robust and specific response to Fe limitation in laboratory cultures and were detected in small volume samples collected from the northeast Pacific, demonstrating the sensitivity of this method. Overall, FLDA1 and ISIP3 expression was inversely related to Fe concentrations and offered insight into the Fe nutritional health of T. oceanica in the field. As T. oceanica is a species tolerant to low Fe, indications of Fe limitation in T. oceanica populations may serve as a proxy for severe Fe stress in the overall diatom community. At two shallow coastal locations, FLD1A and ISIP3 expression revealed Fe stress in areas where dissolved Fe concentrations were high, demonstrating that this approach may be powerful for identifying regions where Fe supply may not be biologically available.
authors.affiliation: Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA.
authors.forename: P Dreux
authors.initials: PD
authors.lastname: Chappell
authors.affiliation: Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA.
authors.forename: LeAnn P
authors.initials: LP
authors.lastname: Whitney
authors.affiliation: Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA.
authors.forename: Joselynn R
authors.initials: JR
authors.lastname: Wallace
authors.affiliation: Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, USA.
authors.forename: Adam I
authors.initials: AI
authors.lastname: Darer
authors.affiliation: Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA.
authors.forename: Samua
authors.initials: S
authors.lastname: Jean-Charles
authors.affiliation: 1] Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA [2] Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA.
authors.forename: Bethany D
authors.initials: BD
authors.lastname: Jenkins
mesh_terms: D017377:Diatoms / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D005418:Flavodoxin / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000528:radiation effects; D007501:Iron / Q000378:metabolism*; D008027:Light; D010140:Pacific Ocean
chemical_list: D005418:Flavodoxin; D007501:Iron