| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2009: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2008: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Research Abstract |
A unique anatomical situation exists in all lamprey speceies in that the adult liver posses no bile ducts. A non-parasitic lamprey in Japan, Lethenteron reissneri, stop feeding at the commencement of metamorphosis and they completely loses its entire bile-transport apparatus during metamorphosis. The degeneration of bile ducts is considered to depend on programmed cell death or apoptosis ; however, molecular evidence of apoptosis is still lacking. By using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and immunohistochemistry with an antibody against active caspase-3 (of the caspase family of cysteine proteases), we showed that the epithelial cells of the cystic duct and gall bladder became TUNEL-positive by metamorphosing stage 2. Immunohistochemical staining of active caspase-3, a key mediator of the apoptotic cascade, showed that the apoptotic signal was initiated in the region around the cystic duct at metamorphic stage 1. In later stages, active caspase-3-positive epithelial cells were also observed in the large intrahepatic bile duct and peripheral small intrahepatic bile ducts. At stage 2, bile canaliculi between hepatocytes were dilated and displayed features resembling canaliculi in cholestasis. Onset of apoptosis around the cystic duct, which is the pathway for the storage of bile juice, and progression of apoptosis toward the large intrahepatic bile duct, which is the pathway for the secretion of bile juice, may lead to temporal intrahepatic cholestasis. Our present study is the first precise spatial and temporal analysis of apoptosis of epithelial cells of the biliary tract system during metamorphosis of any lamprey species.
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