| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2004: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2003: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
The author investigated for subtypes of hemocytes, phagocytosis, and the reactive oxygen intermediate (ROI)-generating system of hemocytes in the Pacific oyster, Crassostrea gigas. Oyster hemocytes were divided into two morphological types : granulocytes and agranulocytes. The ratios between the granulocytes and agranulocytes varied during the year, however, the number of agranulocytes was always greater than that of granulocytes ; approximately 70% of the total cell population was composed of agranulocytes. Granulocytes were more active phagocytes against three species of bacteria tested. Yeast cells were also extensively phagocytized by the granulocytes, but the agranulocytes produced a little phagocytosis of yeast cells. Granulocytes produced large amount of superoxide anion after phorbol stimulation or zymosan phagocytosis, but agranulocytes did not or only slightly produced superoxide anion. A simple method called the phagocytic plaque assay was used to visually present and estimate the phagocytic ability of the hemocytes from the giant Pacific oyster, Crassostrea gigas, using adherent Staphylococcus aureus cells on a plastic dish. Many plaques appeared on the bacterial thin-layer when the oyster hemocytes were overlaid and incubated on killed cells of S.aureus. At both 20℃ and 30℃, the phagocytic ability of the oyster hemocytes were more activated with a significantly larger average area of plaques than were the hemocytes at 10℃. This method was considered to be practical and effective evaluating the qualification of phagocytosis by the oyster hemocytes, however, some problems for the quantification analysis still remain to be solved.
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