Pristionchus pacificus, a nematode with only three juvenile stages, displays major heterochronic changes relative to Caenorhabditis elegans
Abstract
The nematode Pristionchus pacificus (Diplogastridae) has been described as a satellite organism for a functional comparative approach to the model organism Caenorhabditis elegans because genetic, molecular, and cell–biological tools can be used in a similar way in both species. Here we show that P. pacificus has three juvenile stages, instead of the usual four found in other nematodes. Embryogenesis is lengthened and many developmental events that take place during the first juvenile stage in C. elegans occur during late embryogenesis in P. pacificus. Video imaging and transmission electron microscopy revealed no embryonic moult. The timing of later developmental events relative to the moults differs between P. pacificus and C. elegans. In addition, the post–embryonic blast–cell divisions display a specific change in timing between the two species, resulting in heterochrony between different cell lineages, such as vulval and gonadal lineages. Developmental events appear to come into register during the last larval stage. Thus, differences in developmental timing between P. pacificus and C. elegans represent a deep heterochronic change. We designate the three juvenile stages of P. pacificus as J1 to J3. Comparison with other species of the family Diplogastridae indicates that this pattern represents an apomorphic character for the monophylum Diplogastridae.
Additional Information
© 1999 The Royal Society. Received 8 April 1999; Accepted 28 May 1999. We thank Dr. M. Müller, ETH Zürich, for high-pressure freezing of the nematode samples and I. Zimmermann for preparing samples for TEM. P.W.S. is an HHMI investigator, M.A.F. was supported by the Human Frontier Science Program and the Centre National de Recherche Scientifique (France.)Additional details
- PMCID
- PMC1690183
- Eprint ID
- 95489
- Resolver ID
- CaltechAUTHORS:20190514-113356568
- Howard Hughes Medical Institute (HHMI)
- Human Frontier Science Program
- Centre National de la Recherche Scientifique (CNRS)
- Created
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2019-05-14Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field