番木瓜乳管结构及木瓜蛋白酶的免疫电镜研究

LATICIFER ULTRASTRUCTURAL AND IMMUNOCYTO CHEMICAL STUDIES OF PAPAIN IN CARICA PAPAYA

采用免疫细胞化学方法， 以透射电镜观察， 对番木瓜（Ｃａｒｉｃａ ｐａｐａｙａ Ｌ．）乳管分化及木瓜蛋白酶生成的超微结构环境进行了研究。实验结果表明：１．正在分化的乳管细胞内质网分泌旺盛， 线粒体和聚核糖体非常丰富； 之后细胞器逐渐解体， 内质网断裂、膨胀， 细胞壁多处穿孔； 经过内膜系统的重新组合， 成熟乳管被小泡充满， 小泡内有无定形物质凝聚， 已经没有任何细胞器残留， 但原生质膜一直存在。２．经过纯化的兔抗ｃｈｙｍ ｏｐａｐａｉｎ ＩｇＧ 为第一抗体， 羊抗兔ＩｇＧ－金复合物（１０ ｎｍ 直径）为间接抗体， 进行适当的免疫标记反应， 发现金颗粒主要在乳管细胞内， 附近的薄壁细胞及导管只是偶尔出现金标， 说明免疫标记的特异性较强， 通过各种对照试验， 证明了非特异性吸附相当微弱。显示木瓜蛋白酶的原初生成部位是正在分化的乳管细胞的内质网， 它暂时贮存于分泌泡， 随乳管的发育和乳汁其它成分一起被“组装”

Cotyledons of germinating papaya (Carica papaya L.)seeds and exocarp of young fruits were used as materials for study.The ultrastructural changes occurring during differentiation of laticifer and the ultrastructural environment of papain synthesis were studied by means of TEM and immunocytochemistry.Electron microscopic observations showed that the differentiating laticiferous cells were rich in ribosomes and mitochondria. Endoplasmic reticulum (ER) was well developed and apparently active, forming secretory vesicles of various sizes. With further development, organelles were gradually degenerated and autophagy of cytoplasm within vacuole was evident. ER was dilated and split into fragments. Cell wall perforations occurred at several sites of adjacent laticifer elements. Towards maturity, laticifer was fully filled with vesicles containing electron dense materials. Organelles disappeared thoroughly but plasmalemma remained.Sections were incubated with anti chymopapain antibodies followed by goat anti rabbit IgG gold.Labeled gold was found predominantly in ER and the associated vesicles of differentiating laticifer. Several controls were used to establish the specificity of the immunolabeling pattern. Investigations led to the conclusions that ER and polyribosomes were involved in papain synthesis. Papain was stored in the vesicles of ER origin temporally before reorganized into laticiferous vesicles with other components of latex.