Portal de Periódicos da CAPES

Determination of and cathepsin B activity in trophotaenial placental cells of goodeid fishes

1993; Elsevier BV; Volume: 105; Issue: 2 Linguagem: Inglês

10.1016/0305-0491(93)90231-s

0305-0491

I. Kokkala, A.B. Bodine, John P. Wourms,

Reproductive biology and impacts on aquatic species

1. The trophotaenial placenta of the goodeid fishes is an externalized derivative of the hindgut. Trophotaenial epithelial cells transport small molecules or endocytose macromolecules, such as proteins, which serve as nutrient substrates during gestation. 2. Trophotaeniae of the goodeid fishes Ameca splendens, Ilyodon furcidens, and Goodea atripinnis were analyzed for N-acetyl-β-d-glucosaminidase and cathepsin B activity, two enzymes of the endosomallysosomal system. 3. Synthetic conjugates of 4-methylumbelliferone (4-methylumbelliferyl N-acetyl-β-d-glucosaminide) and 7-amino-4-methylcoumarin (benzyloxycarbonyl-phenylalanyl-arginine-4-methyl-7-coumarylamide) were used as substrates for the assays. 4. The specific activity of N-acetyl-β-d-glucosaminidase in the trophotaeniae measured at 34.63 μU/mg protein for A. splendens, 84.81 μU/mg protein for I. furcidens, and 67 μU/mg protein for G. atripinnis, was consistently less than in the control tissues (maternal liver and intestine). 5. In the case of cathepsin B, the specific activity in the trophotaeniae measured at 91.23 mU/mg protein for I. furcidens, and 33.8 mU/mg protein for G. atripinnis, was less than in the intestine but greater than that of the liver for all the species of fish tested. 6. Cathepsin B activity was approximately 1000 × greater than N-acetyl-β-d-glucosaminidase in all three species. 7. There were no significant differences in the specific activity of either enzyme among the three species.