Simulating H systems by P systems

H systems are DNA computing models, based on the operation of splicing. P systems are membrane computing models, where objects can evolve in parallel in a hierarchical membrane structure. In particular, the objects can be strings and the evolution rules can be based on splicing. Both H systems with certain controls on the use of splicing rules and P systems of various types are known to be computationally universal, that is, they characterize the recursively ennumerable languages. So, they are equivalent as the generative power. The present paper presents a direct simulation of some controlled H systems by splicing P systems. We achieve this goal for three basic regulation mechanisms: H systems with permitting contexts, H systems with forbidding contexts, and communicating distributed H systems. We can say that in this way we get a uniform "implementation" of the three types of H systems in the form of a "computing cell".