Molecular cloning and expression analysis of evolutionarily conserved stathmin from Gekko japonicus spinal cord

The cDNA encoding stathmin is identified from the brain and spinal cord cDNA library of Gekko japonicus. It contains a 450 bp open-reading-frame, corresponding to a deduced protein of 149 amino acids. At amino acid level. gecko stathmin shares more than 76.4% identities with vertebrate stathmins, and especially, it shares 100% identity with human stathmin, suggesting that the selective pressure must have been extremely high for the conservation of stathmin during the vertebrates including reptile evolution. Reverse transcriptase polymerase chain reaction (RT-PCR) shows that gecko stathmin is ubiquitously expressed in all tissues examined. In situ hybridization reveals that stathmin transcript mainly appear in the gray matter of spinal cord. The change of stathmin expression in spinal cord after tail amputation is examined by semiquantitative RT-PCR. Stathmin expression increases at 1 day and 3 day after amputation and decreases to the control level at I week. However, the expression level increases again at 2 weeks. These suggest that stathmin may be associated with the immune protection of the injury, as well as in the regeneration of spinal cord.