Root apical meristem (RAM) organization in lycophytes could be a key to understanding the early evolution of roots, but this topic has been insufficiently explored. We examined the RAM organization of lycophytes in terms of cell division activities and anatomies, and compared RAMs among vascular plants. RAMs of 13 species of lycophytes were semi-thin-sectioned and observed under a light microscope. Furthermore, the frequency of cell division in the RAM of species was analyzed using thymidine analogs. RAMs of lycophytes exhibited four organization types: type I (Lycopodium and Diphasiastrum), II (Huperzia and Lycopodiella), III (Isoetes) and RAM with apical cell (Selaginella). The type I RAM found in Lycopodium had a region with a very low cell division frequency, reminiscent of the quiescent center (QC) in angiosperm roots. This is the first clear indication that a QC-like region is present in nonseed plants. At least four types of RAM are present in extant lycophytes, suggesting that RAM organization is more diverse than expected. Our results support the paleobotanical hypothesis that roots evolved several times in lycophytes, as well as in euphyllophytes.

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Replacement of Met510, the axial ligand to the type I Cu in a cuprous oxidase CueO, with Leu afforded the three-coordinated type I Cu, while Gln, Ala, and Thr mutations led to the replacement of the thioether ligand with oxygen ligands (amide carbonyl group and water), and characteristic properties of absorption, circular dichroism, and electron paramagnetic resonance spectra of a variety of Met510 mutants were correlated with the changes in redox potential and enzyme activities.

Highly reproducible bioelectrocatalytic endpoint assays are described. The method is based on a complete redox conversion of a substrate to a redox mediator with a corresponding redox enzyme and an amperometric detection of the reduced mediator on a diffusionally independent microelectrode array. The current reaches a steady state within a few seconds and is proportional to the number of the integrated microelectrodes. The method has successfully been applied to histamine detection at micro-molar level and glucose detection at milli-molar level.

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