Ferredoxin and flavodoxin in eastern Antarctica pack ice

• Published in: Polar Biology
• Main Authors: Pankowski, A, McMinn, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2008
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarc*; Antarctica; Polar Biology; Sea ice
• Online Access: http://www.springerlink.com; https://doi.org/10.1007/s00300-008-0451-y; http://ecite.utas.edu.au/54419

The presence, concentration and distribution ofthe iron regulated proteins, ferredoxin and Xavodoxin, wasinvestigated in pack ice oV eastern Antarctica using SDSPAGEgels. Bands corresponding to ferredoxin and/orXavodoxin were observed in all but eight of the 102 coresections analysed. Flavodoxin was found in most of the icesamples and was strongly correlated with chlorophyll astanding stock. The widespread distribution of Xavodoxinhere is not thought to indicate iron-limitation as many ofthe dominant species, such as Fragilariopsis cylindrus,Cylindrotheca closterium, are known to produce this proteinunder iron-replete conditions and thus the signiWcantcorrelation between Xavodoxin and biomass is likely to bethe result of widespread constitutive Xavodoxin expressionamong the diatoms that commonly inhabit sea ice. Highconcentrations of ferredoxin were predominantly derivedfrom core sections on the Xoes closest to the continent andalso in the upper portion of these Xoes. There was a consistentlack of ferredoxin expression in the high biomass bottomcommunities. The absence of ferredoxin is likely toindicate a reduced supply of iron but the signiWcance of thisreduced iron supply cannot be inferred on the basis of proteinexpression alone. Furthermore, in the present study theobserved variability in the Xavodoxin:ferredoxin ratio maynot simply reXect the iron nutritional status of the community,but probably results from changes in the abundance ofspecies capable of expressing ferredoxin.