Innexins are the proposed structural components of gap junctions in invertebrates. Antibodies that specifically recognize the Caenorhabditis elegans innexin protein INX-3 were generated and used to examine the patterns of inx-3 gene expression and the subcellular sites of INX-3 localization. INX-3 is first detected in two-cell embryos, concentrated at the intercellular interface, and is expressed ubiquitously throughout the cellular proliferation phase of embryogenesis. During embryonic morphogenesis, INX-3 expression becomes more restricted. Postembryonically, INX-3 is expressed transiently in several cell types, while expression in the posterior pharynx persists throughout development. Through immuno-EM techniques, INX-3 was observed at gap junctions in the adult pharynx, providing supporting evidence that innexins are components of gap junctions. An inx-3 mutant was isolated through a combined genetic and immunocytochemical screen. Homozygous inx-3 mutants exhibit defects during embryonic morphogenesis. At the comma stage of early morphogenesis, variable numbers of cells are lost from the anterior of inx-3(lw68) mutants. A range of terminal defects is seen later in embryogenesis, including localized rupture of the hypodermis, failure of the midbody to elongate properly, abnormal contacts between hypodermal cells, and failure of the pharynx to attach to the anterior of the animal.
Bibliographical noteFunding Information:
We thank David Miller, and Ross Francis and Bob Waterston for providing mAb 5.6 and MH27, respectively. We thank Mike Portereiko and Susan Mango for communicating results prior to publication. We thank Marie-Christine Paupard for help in electronmicroscopy. This research was supported by NIH grants GM56367 (to J.E.S) and RR12596 (to D.H.H.), and NSF grant 9601282 (to T.A.S. and J.E.S.). Some strains were obtained from the Caenorhabditis Genetics Center, supported by a contract between the NIH Center for Research Resources and the University of Minnesota.
- C. elegans
- Gap junctions