Author
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Bakst, Murray |
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HOLM, L - SWEDISH U OF AGRIC SCI |
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Submitted to: Poultry Science
Publication Type: Research Notes Publication Acceptance Date: 6/1/2002 Publication Date: 11/1/2002 Citation: Bakst, M.R., Holm, L. Impact of egg storage on carbonic anhydrase activity during early embryogenesis in the turkey. Poultry Science. 82:1193-1197, 2003. Interpretive Summary: Carbonic anhydrase (CA) is an important enzyme that plays roles in the conversion of carbon dioxide to bicarbonate, pH regulation, and in sub- embryonic fluid formation in bird embryos. While turkey egg storage longer than 10 days is known to increase the rate of embryo mortality, little is know of the biological mechanisms that cause embryonic death. Therefore, we examined the impact of turkey egg storage on CA activity in the fresh laid egg through 72 h of incubation. Carbonic anhydrase activity, which was not affected by egg storage for 21 days at 18C, was initially seen in the area just below the perimeter of the embryo after 24 hr incubation. By 48 h and 72 h the yolk sac, which transports water and nutrients from the albumen and yolk into the embryo, had formed. The dominant cell type in the yolk sac, the endoderm, stained strongly positive for CA. In contrast, the other cell layers were negative. Our observations support recent studies showing CA activity associated with the endodermal cells of the yolk sac in other bird embryos. This work also demonstrated that if an embryo survives cold egg storage, CA activity does not appear to be affected. This work is useful to poultry and avian embryologists studying the impact of egg storage and incubation conditions on the growth and development of the embryo. Technical Abstract: Carbonic anhydrase is an enzyme that plays important roles in the conversion of carbon dioxide to bicarbonate, acid-base balance, and in sub- embryonic fluid formation in the early Japanese quail embryo. While turkey egg storage longer than 10 days is known to increase the rate of embryo mortality, little is know of the biological mechanisms that contribute to this phenomenon. In this study, we examined the impact of turkey egg storage on carbonic anhydrase activity in the fresh laid egg through 72 h of incubation. Carbonic anhydrase activity, which was not affected by egg storage for 21 days at 18C, was first observed in the germ wall, that area of yolk subjacent to the area opaca, after 24 hr incubation. By 48 h and 72 h the yolk sac had formed with the yolk sac endoderm strongly positive for carbonic anhydrase. In contrast, mesodermal and ectodermal layers were negative. Our observations support recent studies showing carbonic anhydrase activity associated with the endodermal cell of the yolk sac in Japanese quail embryos and that such activity appears to be involved with sub-embryonic fluid formation in the turkey. This work also demonstrated that that if an embryo survives cold egg storage, carbonic anhydrase activity does not appear to be affected. |
