Document Type : Research Paper
Authors
1
MSc. Fisheries Department, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, I.R. Iran
2
Prof. Fisheries Department, Faculty of Natural Resources, University of Tehran, Karaj, I.R. Iran
3
Associate Prof. Fisheries Department, Faculty of Natural Resources and Marine Science, Tarbiat Modares University, Noor, I.R. Iran
4
Assistant Prof. Fisheries Department, Faculty of Agriculture and Natural Resources, University of Hormozgan, Bnadar Abbas, I.R. Iran
Abstract
The present study investigated the effects of different concentrations of trypsin to eliminate egg stickiness of the Persian sturgeon (Acipenser persicus). Embryo survival rate and adhesiveness removal time were the criteria used to compare our method with the common methodology using clay. Also, thickness of corion was measured during the experiment using histological assay. The eggs were exposed to four different enzyme concentrations (1, 3, 6 and 12 IU/ml) for 30 minutes after fertilization of eggs and washing with water. In addition, one group was exposed to clay and considered as control. All five groups (each with three replicates with 150 eggs in each replicate) were sampled at the beginning of experiment at time 0 (when egg activation was done and jelly coat was formed) and another three times each with 10‑minute interval. Sampled eggs were fixed in Bouin solution. In each treatment, adhesiveness removal time was recorded. To determine embryo survival rate, sampling was done 60 hours after the fertilization. The highest survival rate with 86.9 ± 2/19% was found in 6 IU/ml treatment., which was significantly higher (P<0.05) than the those of the other groups (75.2 ± 0.88%, 77.1 ± 2.1%, 77.3 ± 2.26% and 77 ± 2.75% in 1 IU/ml, 3 IU/ml, 12 IU/ml and control, respectively). The shortest adhesiveness time was six minutes for 12 IU/ml treatment. The adhesiveness time for 1, 3, 6 IU/ml and control groups were 19, 15, 11 and 23 minutes, respectively. Histological studies revealed no physical damage in the control and all treated groups. The results of this study showed that jelly coat thickness was correlated negatively with time in different treatments. In conclusion, trypsin is more reliable method for de‑adhesion of Persian sturgeon egg compare to the common method. The suggestive concentration of trypsin is 6 IU/ml that removes the adhesiveness within 11 minutes.
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