title: Transmission electron microscope studies of the nuclear envelope in Caenorhabditis elegans embryos.
abstract: Nuclear membranes and nuclear pore complexes (NPCs) are conserved in both animals and plants. However, the lamina composition and the dimensions of NPCs vary between plants, yeast, and vertebrates. In this study, we established a protocol that preserves the structure of Caenorhabditis elegans embryonic cells for high-resolution studies with thin-section transmission electron microscopy (TEM). We show that the NPCs are bigger in C. elegans embryos than in yeast, with dimensions similar to those in higher eukaryotes. We also localized the C. elegans nuclear envelope proteins Ce-lamin and Ce-emerin by pre-embedding gold labeling immunoelectron microscopy. Both proteins are present at or near the inner nuclear membrane. A fraction of Ce-lamin, but not Ce-emerin, is present in the nuclear interior. Removing the nuclear membranes leaves both Ce-lamin and Ce-emerin associated with the chromatin. Eliminating the single lamin protein caused cell death as visualized by characteristic changes in nuclear architecture including condensation of chromatin, clustering of NPCs, membrane blebbing, and the presence of vesicles inside the nucleus. Taken together, these results show evolutionarily conserved protein localization, interactions, and functions of the C. elegans nuclear envelope.
authors.affiliation: Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
authors.forename: Merav
authors.initials: M
authors.lastname: Cohen
authors.forename: Yonatan B
authors.initials: YB
authors.lastname: Tzur
authors.forename: Esther
authors.initials: E
authors.lastname: Neufeld
authors.forename: Naomi
authors.initials: N
authors.lastname: Feinstein
authors.forename: Michael R
authors.initials: MR
authors.lastname: Delannoy
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Wilson
authors.forename: Yosef
authors.initials: Y
authors.lastname: Gruenbaum
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology / Q000648:ultrastructure*; D016923:Cell Death; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure*; D007150:Immunohistochemistry; D034882:Lamins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D009685:Nuclear Envelope / Q000648:ultrastructure*; D034881:Nuclear Lamina; D009687:Nuclear Proteins; D034622:RNA Interference; D013946:Thymopoietins / Q000378:metabolism
chemical_list: D034882:Lamins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D013946:Thymopoietins; C092710:emerin