Astrid Sigel has studied languages and was an editor of the Metal Ions in Biological Systems series (until Volume 44) and also of the Handbooks on Toxicity of Inorganic Compounds (1988), on Metals in Clinical and Analytical Chemistry (1994; both with H. G. Seiler), and on Metalloproteins (2001; with Ivano Bertini) (Dekker, New York). Helmut Sigel is Emeritus Professor (2003) of Inorganic Chemistry at the University of Basel, Switzerland, and a previous editor of the MIBS series until Volume 44. He serves on various editorial and advisory boards, published over 300 articles on metal ion complexes of nucleotides, coenzymes, and other biologically relevant ligands. He lectured worldwide and was named Protagonist in Chemistry (2002) by ICA (issue 339). Among further honors are the P. Ray Award (Indian Chemical Society, of which he is also an Honorary Fellow), the Werner Award (Swiss Chemical Society), a Doctor of Science honoris causa degree (Kalyani University, India), appointments as Visiting Professor (e.g., Austria, China, UK) and Endowed Lectureships. Roland K. O. Sigel is Assistant Professor (2003) of Inorganic Chemistry at the University of Zurich, Switzerland, endowed with a Forderungsprofessur of the Swiss National Science Foundation. He received his doctoral degree summa cum laude (1999) from the University of Dortmund, Germany, working with Bernhard Lippert; thereafter he spent nearly three years at Columbia University, New York, USA, in the group of Anna Marie Pyle (now Yale University); during the six years abroad he received several fellowships from various sources. His research focuses on the structural and catalytic role of metal ions in ribozymes, especially group II introns, and on related topics. He was also an editor of Volumes 43 and 44 of the MIBS series.