ISSN: 2639-216X
Authors: Ramasamy Sivakumar M and Shanthi R*
The aim of the present study is to examine phenoloxidase (PO), a copper-containing enzyme that plays a crucial role in the immune responses of arthropods, especially crustaceans and insects. However, PO activity is present in the plasma of the hemolymph without pathogenic infections. Here we report the PO activity in the plasma of M. rosenbergii was spectrophotometrically studied. The phenylthiourea (PTU) inhibition of PO activity was found to be the highest at a 10 mM concentration. The determination of PO activity was also highest activated by trypsin (2 mg.ml-1), detergents like sodium dodecyl sulphate (SDS; 8 mg.ml-1) and laminarin (4 mg.ml-1) enzyme expression. The effect of divalent cations on PO activity like sodium chloride (100 mM), calcium chloride, magnesium chloride, manganese chloride, and potassium chloride (10 mM) affected the activation of PO activity in trypsin, SDS, and laminarin. However, these divalent cations only slightly affected PTU inhibition of PO activity. In addition to calcium chloride, the PO activity with trypsin and laminarin is more or less the same as with control, but a great enhancement was found in SDS, which indicates that the combination of SDS with calcium chloride is required for increasing the PO activity in M. rosenbergii. The concentration of ethylenediaminetetraacetic acid (EDTA) of 1–10 mM has the maximum inhibition in PTU and activation of trypsin, SDS, and laminarin, which indicates that EDTA is a divalent cation chelator that affects the PO activity in M. rosenbergii. Hence, an attempt has been made to optimize the conditions for inhibitor, activators, divalent cations, EDTA sensitivity, and phenoloxidase activity in the plasma of the freshwater prawn M. rosenbergii.
Keywords: Macrobrachium rosenbergii; Phenoloxidase; Enzyme Chemical Reactions; Invertebrate Humoral Immune System
