Acknowledgements
This study was partially supported by a grant from Pará
State Secretary of Science and Technology, contract no. 067/2008
(SEDECT/FAPESPA/PA). Delana A.M. Bezerra and Jane H.L. Kaiano
received a Grant fellowship from the Brazilian National Council
for the Development of Science and Technology (CNPq). We gratefully
acknowledge the valuable technical support provided by Mrs.
Euzeni Maria de Fátima Menezes.