Invited Lectures -- Biological Roots and Applications of P Systems: Further Suggestions -- Formalizing Spherical Membrane Structures and Membrane Proteins Populations -- Quorum Sensing: A Cell-Cell Signalling Mechanism Used to Coordinate Behavioral Changes in Bacterial Populations -- A Modeling Approach Based on P Systems with Bounded Parallelism -- Synchrony and Asynchrony in Membrane Systems -- MP Systems Approaches to Biochemical Dynamics: Biological Rhythms and Oscillations -- Modeling Signal Transduction Using P Systems -- Regular Papers -- Extended Spiking Neural P Systems -- Towards a Characterization of P Systems with Minimal Symport/Antiport and Two Membranes -- Expressing Control Mechanisms of Membranes by Rewriting Strategies -- Tissue P Systems with Communication Modes -- Towards a Hybrid Metabolic Algorithm -- Towards a P Systems Pseudomonas Quorum Sensing Model -- Membrane Systems with External Control -- A Case Study in (Mem)Brane Computation: Generating Squares of Natural Numbers -- Computing with Genetic Gates, Proteins, and Membranes -- Classifying States of a Finite Markov Chain with Membrane Computing -- Partial Knowledge in Membrane Systems: A Logical Approach -- Tau Leaping Stochastic Simulation Method in P Systems -- P Machines: An Automata Approach to Membrane Computing -- Modeling Dynamical Parallelism in Bio-systems -- P Colonies with a Bounded Number of Cells and Programs -- P Finite Automata and Regular Languages over Countably Infinite Alphabets -- Mitotic Oscillators as MP Graphs -- Infinite Hierarchies of Conformon-P Systems -- A Protein Substructure Based P System for Description and Analysis of Cell Signalling Networks -- Characterizations of Some Restricted Spiking Neural P Systems -- A Membrane Algorithm for the Min Storage Problem -- P Systems with Symport/Antiport and Time -- Towards Probabilistic Model Checking on P Systems Using PRISM -- Graphical Modeling of Higher Plants Using P Systems -- Identifying P Rules from Membrane Structures with an Error-Correcting Approach -- Computational Completeness of Tissue P Systems with Conditional Uniport -- Distributed Evolutionary Algorithms Inspired by Membranes in Solving Continuous Optimization Problems.

This book constitutes the thoroughly refereed extended postproceedings of the 7th International Workshop on Membrane Computing, WMC 2006, held in Leiden, Netherlands in July 2006. The 27 revised full papers presented together with 7 invited papers went through two rounds of reviewing and improvement. The papers in this volume cover all the main directions of research in membrane computing, ranging from theoretical topics in mathematics and computer science, and to application issues. Special attention was paid to the interaction of membrane computing with biology, focusing both on the biological roots of membrane computing and on applications of membrane computing in biology and medicine.