Protein, Vitellogenin, and Vitellin Levels in the Hemolymph and Ovaries during Ovarian Development in <i>Penaeus semisulcatus</i> (de Haan)

Abstract

The concentration of vitellogenin (Vg) in the hemolymph of Penaeus semisulcatus was found to increase from an average of 50 μg ml-1 to 439 μg ml-1 in female shrimp during ovarian development. The most significant increase in Vg occurred concomitant with the increase in the vitellin (Vt) content of oocytes with an average diameter (AOD) ranging between 150 and 250 μm. The amount of Vt in the oocytes was found to increase linearly from a mean of 0.0126 mg to 4.55 mg per gm body weight. However, the percentage of Vt in the total protein was found to decrease, from 67% in ovaries with AOD of 150-250 μm, to 39.7% in ovaries with AOD of 350 μm or larger. The volume of the hemolymph was found to be 0.4 ml per gm body weight and did not change significantly during ovarian development. Assuming that Vg in the hemolymph represents either an extraovarian origin of Vt or an active secretion from the ovary, a turnover rate of two to three times per day was calculated over one full cycle of oocyte development. However, during the most significant increase in Vt in the ovary (in ovaries with AOD of 150-250 μm), the turnover rate in the hemolymph could reach seven to eight times per day. The results lead to the conclusion that the contribution of Vg to the formation of Vt in the ovary is quantitatively insignificant.