Haemocytes and blastogenetic cycle in the colonial ascidian Botryllus schlosseri:: a matter of life and death
Haemocytes and blastogenetic cycle in the colonial ascidian Botryllus schlosseri:: a matter of life and death
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DOI：
10.1007/s00441-007-0513-4
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发表时间：
2008-02-01
影响因子：
3.6
通讯作者：
Cima, Francesca
中科院分区：
文献类型：
--
作者：
Ballarin, Loriano;Menin, Adams;Cima, Francesca
海鞘类 Botryllus schlosseri 群体的特征是反复出现的胚芽发生周期。这个循环开始于新一代的动物体打开虹吸管，结束于接管，此时成年动物体停止过滤并逐渐被新一代的芽吸收和取代，达到功能成熟。在世代更替过程中，群体中发生大量细胞凋亡，主要是在老动物的组织中。在本研究中，我们研究了血细胞在集落胚芽发生周期中的行为，包括细胞死亡的发生和参与诱导细胞凋亡的分子的表达。我们的结果表明，在接管过程中，血细胞裂解物中的 caspase-3 活性增加。此外，大约 20%-30% 的血细胞在其质膜外层表达磷脂酰丝氨酸，显示 DNA 片段化，并且 caspase-3 免疫阳性。衰老细胞很快被循环吞噬细胞吞噬，吞噬细胞一旦吞噬了受影响的细胞，通常就会进入细胞凋亡状态。垂死的细胞和尸体被世代更替期间出现在循环中的新一代细胞所取代。
A recurrent blastogenetic cycle characterizes colonies of the ascidian Botryllus schlosseri. This cycle starts when a new zooid generation opens its siphons and ends with take-over, when adult zooids cease filtering and are progressively resorbed and replaced by a new generation of buds, reaching functional maturity. During the generation change, massive apoptosis occurs in the colony, mainly in the tissues of old zooids. In the present study, we have investigated the behaviour of haemocytes during the colonial blastogenetic cycle, in terms of the occurrence of cell death and the expression of molecules involved in the induction of apoptosis. Our results indicate that, during take-over, caspase-3 activity in haemocyte lysates increases. In addition, about 20%-30% of haemocytes express phosphatidylserine on the outer leaflet of their plasma membrane, show DNA fragmentation and are immunopositive for caspase-3. Senescent cells are quickly ingested by circulating phagocytes that frequently, having once engulfed effete cells, in turn enter apoptosis. Dying cells and corpses are replaced by a new generation of cells that appear in the circulation during the generation change.