Molecular probes for the cell walls of brown algae

The brown algae are an abundant source of renewable biomass that do not require arable land or fresh water for cultivation. Cell walls of the brown algae contain a range of unique polysaccharides with useful bioactivities; namely the sulphated fucans and alginate. The generation and characterisation of ten new monoclonal antibodies (MAbs) towards components of brown algal cell walls are described. Four MAbs, BAM1 to BAM4, recognise un-sulphated (BAM1) and sulphated (BAM2/3/4) structures of the sulphated fucans. Six MAbs, GIN1 to GIN6, recognise different structures of the alginate, ranging from high mannuronate content (GIN4) to high guluronate content (GIN6). The combination of these new MAbs, pre-existing knowledge of the brown algal cell walls and, techniques commonly used in land plant cell walls have allowed an extensive study of cell wall architecture in the brown algae. The extraction and fractionation of the cell wall has revealed that the sulphated fucans and alginate are distributed throughout the cell wall architecture and that there are differences in cell wall architecture between orders of the brown algae. Investigation into the abundance of sulphated fucans in the intertidal zone showed trends for increased sulphated fucan content higher up the intertidal zone (as determined by BAM3 and BAM4), but also revealed a ubiquitously distributed set of sulphated fucans (as determined by BAM1 and BAM2). Within tissues of the algae; sulphate fucans and alginate are spatially distributed both in terms of abundance and incorporation into the cell wall architecture – and these traits are shared between species of Fucus. Use of indirect immunohistochemistry allowed dissection of the sulphated fucan and alginate distribution in muro (in wall); revealing cell type specificity and patterning of the polysaccharides.