1. Laboratory of Microbial and Molecular Evolution, Dept. of Evolutionary Biology; University of Florence; Via Romana 19; I-50125; Firenze; Italy
2. Institute of Protein Biochemistry; National Research Council; Naples; Italy
3. Department of Organic Chemistry and Biochemistry; University of Naples Federico II; Naples; Italy
4. Department of Animal Biology and Marine Ecology; University of Messina; Messina; Italy