Epithelia, an Evolutionary Novelty of Metazoans
Epithelia, an Evolutionary Novelty of Metazoans
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DOI：
10.1002/jez.b.21442
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发表时间：
2012-09-01
影响因子：
2.2
通讯作者：
Riesgo, Ana
中科院分区：
文献类型：
--
作者：
Leys, Sally P.;Riesgo, Ana
在动物进化过程中，当细胞开始相互粘附时，它们最初的功能可能是作为群体。封闭和控制内部环境的上皮的形成可能是区分个体动物和群体的第一个事件。为了更好地了解第一个上皮是什么时候产生的，它的特征是什么，我们评估了海绵上皮的形态学、功能和分子特征，这里考虑了第一个后生动物的现存代表。特别是，我们发现来自海绵的新的类似于cludin的序列与来自果蝇的序列最接近，这些序列在分隔连接处具有屏障功能。我们还发现，基底膜（BM）的主要成分IV型胶原蛋白存在于钙质海绵中，并且我们证实了其他海绵中也存在IV型样胶原蛋白（海绵短链胶原蛋白）。虽然海绵和其他后生动物一样，上皮具有特化的等级，具有不同的连接和基底膜的复杂性，但功能性上皮的主要特征，即密封和控制内部环境离子组成的能力，是最简单的海绵上皮的特性，因此第一批后生动物可能也具有这些特征的上皮，我们认为这是真正的上皮。J. Exp. Zool。（Mol. Dev. evolution .）318 b: 438447、2012。(c) 2011 Wiley期刊公司
At the point in animal evolution when cells began to adhere to each other they presumably initially functioned as colonies. The formation of an epithelium that enclosed and controlled an internal milieu would have been the first event to distinguish an individual animal from a colony. To better understand when the first epithelium arose and what its characteristics were, we evaluate the morphological, functional, and molecular characters of epithelia in sponges, considered here the extant representatives of the first metazoans. In particular, we show new claudin-like sequences from sponges align most closely with sequences from Drosophila that have a barrier function in septate junctions. We also show that type IV collagen, the main component of the basement membrane (BM), is present in calcareous sponges, and we confirm the presence of type IV-like collagen (spongin short chain collagen) in other sponges. Though in sponges as in other metazoans the epithelium has grades of specialization with varying complexity of junctions and the BM, the main character of a functional epithelium, the ability to seal and control the ionic composition of the internal milieu, is a property of even the simplest sponge epithelium, and therefore the first metazoans likely also had epithelia with these characteristics, which we consider a true epithelium. J. Exp. Zool. (Mol. Dev. Evol.) 318B:438447, 2012. (c) 2011 Wiley Periodicals, Inc.