Phosphatized Polar Lobe-Forming Embryos from the Precambrian of Southwest China

Creators: Chen, Jun-Yuan; Bottjer, David J.; Davidson, Eric H.; Dornbos, Stephen Q.; Gao, Xiang; Yang, Yong-Hua; Li, Chia-Wei; Li, Gang; Wang, Xiu-Qiang; Xian, Ding-Chang; Wu, Hung-Jen; Hwu, Yeu-Kuang; Tafforeau, Paul

Abstract

In developing embryos of some extant spiralian animals, polar lobe formation is one of the symmetry-breaking mechanisms for segregation of maternal cytoplasmic substances to certain blastomeres and not others. Polar lobe formation leads to unique early cleavage morphologies that include trilobed, J-shaped, and five-lobed structures. Fossil embryos similar to modern lobeforming embryos are recognized from the Precambrian Doushantuo Formation phosphates, Weng'an, Guizhou Province, China. These embryos are abundant and form a developmental sequence comparable to different developing stages observed in lobe-forming embryos of extant spiralians. These data imply that lobe formation is an evolutionarily ancient process of embryonic specification.

Additional Information

© 2006 American Association for the Advancement of Science. 8 February 2006; Accepted 27 April 2006. Supported by Chinese Academy of Science grant KZCX3-SW-141; National Science Foundation of China grants 42432006, 40302004, 10490190, 60172042, and 10490194; 111 Project and 985-2 Project of Nanjing University, LPS of Nanjing Institute of Geology & Paleontology, NASA/Ames grant NAG2-1541, and an NSC grant. We thank the European Synchrotron Radiation Facility, Taiwan NSRRC, and Beijing Synchrotron Radiation Facility and Photon Factory for provision of synchrotron radiation facilities.

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