Thursday, May 29, 2008 - 4:15 PM
620

Detecting single cell algal nutritional content and nitrogen uptake in natural benthic assemblages

Justin N. Murdock1, Walter K. Dodds1, and David L. Wetzel2. (1) Division of Biology, Kansas State University, 104 Ackert Hall, Manhattan, KS 66506, (2) Microbeam Molecular Spectroscopy Laboratory, Kansas State University, Manhattan, KS 66506

Measuring species specific responses of benthic algae to environmental change has been hindered by technical limitations such as the relatively large sample size required for analysis, and difficulty sorting species from natural assemblages. Fourier transform infrared (FT-IR) microspectroscopy measures the absorbance of distinct wavelengths of the infrared spectrum by macromolecules (e.g. proteins, lipids, carbohydrates, and phosphodiesters) in a sample. We applied this technique to field-collected benthic algae and measured the nutritional content in single cell diatoms and individual cells comprising Cladophora filaments (~25µm x 25µm measurement area). We also imaged the nutritional content (~7µm x 7µm pixel size) of whole Cladohpora cells.  Cellular and subcellular nitrogen (N) uptake was estimated by detecting the gradual incorporation of 15N (as K15NO3) from the surrounding water into cellular proteins by monitoring shifts in protein (amide II) absorbance peaks due to the heavier isotope.  We found high protein and lipid heterogeneity in cells in close proximity, and even among adjacent cells along a filament.  A 4 fold increase in nitrogen uptake was detected along a 4 mm Cladophora filament.  FT-IR microspectroscopy has great potential to advance both basic and applied benthic algal research.      


Web Page: periphyton, nitrogen, nutrition

See more of Periphyton II
See more of Contributed Sessions

See more of The Nabs 56th Annual Meeting (25-28 May, 2008)