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Nat Com:活腔棘鱼和化石腔棘鱼的肺

摘要 : 本期Nature Communications上发表的一篇论文证实,活腔棘鱼(一度被认为已经灭绝的深水鱼)的确有肺。虽然这个肺已不再被认为能发挥功能,但它提供了关于其远古亲缘种何以能够生活在距今大约4.1亿年前的线索。

 本期Nature Communications上发表的一篇论文证实,活腔棘鱼(一度被认为已经灭绝的深水鱼)的确有肺。虽然这个肺已不再被认为能发挥功能,但它提供了关于其远古亲缘种何以能够生活在距今大约4.1亿年前的线索。

腔棘鱼是大的肉鳍鱼,直到一个活的种(Latimeria chalumnae)1938年在南非近海被发现之前都被认为已灭绝,从而为它们赢得了所谓“活化石”的地位。与化石种相比,Latimeria缺少一个特征性的“钙化肺”(这种肺被认为是对浅水环境的一种适应),而且目前还不知道这些化石种的任何残迹是否还保留在腔棘鱼当今的解剖结构中。

Paulo Brito及同事利用被称为“X-射线断层扫描”的一种成像方法生成了活腔棘鱼种Latimeria chalumnae的肺的五个发育阶段的3D重建。他们证实,虽然这个种在早期胚胎中具有一个发育良好的、有可能发挥功能的肺,但这个肺的生长在后来的胚胎阶段、未成年阶段和成年阶段相当大程度地减慢了,最终变得没有功能了(退化了)。

作者还报告说,在成年Latimeria标本的这一退化肺周围散布着较小的、柔性的盘,并且提出它们与化石腔棘鱼的“钙化肺”有可比性。虽然这些结构在用鳃呼吸的活种当中已不再使用,但对化石种来说这些盘却被认为在调控肺活量中曾经起过一定作用,而当物种适应了深水环境后,这些盘便最终消失了。

原文链接:

Allometric growth in the extant coelacanth lung during ontogenetic development

原文摘要:

Coelacanths are lobe-finned fishes known from the Devonian to Recent that were long considered extinct, until the discovery of two living species in deep marine waters of the Mozambique Channel and Sulawesi. Despite extensive studies, the pulmonary system of extant coelacanths has not been fully investigated. Here we confirm the presence of a lung and discuss its allometric growth inLatimeria chalumnae, based on a unique ontogenetic series. Our results demonstrate the presence of a potentially functional, well-developed lung in the earliest known coelacanth embryo, and its arrested growth at later ontogenetic stages, when the lung is clearly vestigial. The parallel development of a fatty organ for buoyancy control suggests a unique adaptation to deep-water environments. Furthermore, we provide the first evidence for the presence of small, hard, flexible plates around the lung in L. chalumnae, and consider them homologous to the plates of the ‘calcified lung’ of fossil coelacanths.

来源: Nature Communications 浏览次数:0

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