Embryonic axis specification in nematodes: evolution of the first step in development.

Published

Journal Article

In 1828, von Baer proposed that the early stages of development must be the most conserved [1]. Others have since countered that the middle stages of development are the most conserved [2]. To address whether the earliest step in pattern formation can evolve, we have examined how asymmetry along the antero-posterior (AP) axis is generated in various nematode species. AP asymmetry is specified in Caenorhabditis elegans at fertilization by the sperm, which directs a cytoplasmic rearrangement that segregates critical factors such as the P granules to one side of the uncleaved embryo [3,4]. We found that AP asymmetry is generated differently in another nematode species: the sperm is not used to specify AP asymmetry, there are no signs of cytoplasmic movements, and P granules are segregated differently. Despite these differences, development from the two-cell stage is remarkably similar in the two species. We have reconstructed the evolutionary history of these mechanisms by analyzing the development of 30 nematode species and mapping the results onto a molecular phylogeny of the nematodes [5]. The results suggest that a new mechanism for axis specification evolved in an ancestor of some of the relatives of C. elegans. We conclude that this fundamental step in development can evolve without affecting other aspects of development.

Full Text

Cited Authors

  • Goldstein, B; Frisse, LM; Thomas, WK

Published Date

  • January 1998

Published In

Volume / Issue

  • 8 / 3

Start / End Page

  • 157 - 160

PubMed ID

  • 9443914

Pubmed Central ID

  • 9443914

Electronic International Standard Serial Number (EISSN)

  • 1879-0445

International Standard Serial Number (ISSN)

  • 0960-9822

Digital Object Identifier (DOI)

  • 10.1016/s0960-9822(98)70062-4

Language

  • eng