1. International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
2. Department of Genetic Engineering, Libyan Biotechnology Research Center, Tripoli P.O. Box 30313, Libya
3. Faculty of Medicine, University of Southampton, Southampton SO17 1BJ, UK
4. Department of Life Sciences, University of Trieste, Via A. Valerio, 28, 34127 Trieste, Italy