Natural Apoptosis During the Blastogenetic Cycle of the Colonial Ascidian Botryllus schlosseri: A Morphological Analysis
Natural Apoptosis During the Blastogenetic Cycle of the Colonial Ascidian Botryllus schlosseri: A Morphological Analysis
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DOI：
10.2108/zsj.27.96
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发表时间：
2010-02-01
影响因子：
0.9
通讯作者：
Manni, Lucia
中科院分区：
文献类型：
--
作者：
Ballarin, Loriano;Schiavon, Filippo;Manni, Lucia
复合海鞘Botryllus schlosseri的殖民地进行定期的世代变化，在此期间，成人zooids逐渐被吸收，并取代生长的芽。世代变化或接管的特征在于细胞凋亡引起的大量细胞死亡，如核浓缩、半胱天冬酶的活化、抗哺乳动物Bax、Fas和FasL抗体识别的分子的过表达、类动物组织衰老细胞表面分子表达的变化以及类动物组织中循环吞噬细胞的募集（其确保死亡细胞的完全清除）所示。整个过程在20 ℃下持续24-36小时，并根据老游动体的收缩程度分为四个亚阶段。在目前的工作中，我们进行了详细的形态学分析的事件发生在Zooid组织在接管的substages。结果表明，在表皮，鳃周上皮细胞，和心脏中发现的痕迹，在晚期亚阶段，但很容易发现在鳃篮开始后2-4小时的代变化，从而确认细胞死亡的前后进展，至少在消化系统。
Colonies of the compound ascidian Botryllus schlosseri undergo regular generation changes, during which adult zooids are progressively resorbed and replaced by growing buds. The generation change, or take-over, is characterized by massive cell death by apoptosis, as indicated by nuclear condensation, activation of caspases, overexpression of molecules recognized by antibodies against mammalian Bax, Fas, and FasL, changes in the expression of surface molecules by senescent cells of zooid tissues, and recruitment of circulating phagocytes in zooid tissues which ensure the complete clearing of dying cells. The entire process lasts 24-36 h at 20 degrees C and has been subdivided, on the basis of the degree of contraction of old zooids, into four substages. In the present work, we carried out a detailed morphological analysis of the events occurring in zooid tissues during the take-over substages. Results indicate that traces of apoptosis can be found in the epidermis, peribranchial epithelium, and heart in the late substage but are easily found in the branchial basket 2-4 h after the beginning of the generation change, thus confirming the antero-posterior progression of cell death, at least in the alimentary system.