Samples of females were taken along

Samples of females were taken along vitellogenesis on a 7-day
basis. Tissue samples (ovary, hepatopancreas) were dissected out
and homogenized in a Potter-type homogenizer (Thomas Scientific,
Swedesboro, NJ) with phosphate buffer 50 mM, pH 7.4 containing
0.8 lM aprotinin (Trasylol, Mobay Chemical, New York, USA).
Hemolymph was obtained by puncturing the cephalic sinus using
a syringe containing 0.1 N sodium citrate as anticoagulant.
Female specimens at different stages of ovary maturation were
collected weekly from a water course close to the Río de la Plata
river, Argentina from September to November to draw correlations
between gonadosomatic index (GSI) and the amount of VTG/LV.
GSI was calculated as the gonad weight (g)  100/body weight
(g). Total protein concentration was measured colorimetrically by
the method of Lowry (Lowry et al., 1951).