Developmental interdeterminacy in embryos of the leech Helobdella triserialis.
Developmental interdeterminacy in embryos of the leech Helobdella triserialis.
复制标题
三串水蛭胚胎发育的不确定性。
DOI：
10.1016/0012-1606(84)90146-5
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发表时间：
1984
影响因子：
2.7
通讯作者：
Blair,SS
中科院分区：
文献类型：
--
作者：
Weisblat,DA;Blair,SS
在水蛭Helobdella triserialis的胚胎发育过程中，四个配对位置可识别的外胚层端胚细胞（N，O，P和Q）中的每一个都产生一个胚细胞后代的带，该胚细胞后代与同侧的带合并成一个胚带。左和右胚带合并成胚板，其产生水蛭的节段组织，并且其中每个端细胞的后代产生表皮和神经元细胞的特征模式。这里报道的实验表明，位置确定的O端细胞有时产生的P模式，反之亦然。这些终末细胞的生殖性的逆转被证明对应于它们的母细胞带形成交叉，因此它们的带在生殖带中的位置也被逆转。因此，与o和p母细胞命运相关的是小带在胚带中的位置，而不是亲代端细胞的位置。此外，两种类型的消融实验已经表明，在没有生成性P终末细胞后代的情况下，那些通常会产生O模式的细胞会采取新的命运，并在神经系统中产生P模式，无论是在节段神经节中的总体模式水平，还是在周围神经系统中识别的神经元水平。如果相关的话，这些现象表明，O和P端母细胞，这是从对称分裂的OP protoblasts，有一个共同的发展多能性。在这种情况下，它们后代的命运是根据新生生发带中的相对位置分层确定的，其中P型命运是首选的。
In embryonic development of the leechHelobdella triserialis, each of the four pairedpositionally identifiable, ectodermal teloblasts (N, O, P, and Q) generates a bandlet of blast cell progeny that merges with ipsilateral bandlets into a germinal band. Left and right germinal bands coalesce into the germinal plate which gives rise to the segmental tissues of the leech and wherein the progeny of each teloblast generate a characteristic pattern of epidermal and neuronal cells. Experiments reported here show that the positionally identified O teloblast sometimes generates the P pattern and vice versa. The reversal of these teloblasts'generativeidentities was shown to correspond to the formation of chiasmata by their blast cell bandlets, so that the positions of their bandlets in the germinal band are reversed as well. Thus it is the position of the bandlet in the germinal band, rather than the position of the parent teloblast, which correlates with the fate of o and p blast cells. Moreover, two types of ablation experiments have shown that, in the absence of generative P teloblast progeny, those cells which would normally generate the O pattern take on a new fate and give rise to the P pattern in the nervous system, both at the gross pattern level in the segmental ganglia, and at the level of identified neurons in the peripheral nervous system. If related, these phenomena suggest that the O and P teloblasts, which derive from the symmetric cleavage of the OP proteloblasts, have a common developmental pluripotency. And in that case, the fates of their progeny are determined hierarchically on the basis of relative position in the nascent germinal band, with P-type fate being preferred.