The embryonic cell lineage of the nematode Halicephalobus gingivalis (Nematoda: Cephalobina: Panagrolaimoidea)

Abstract

Summary -This paper describes the nearly complete embryonic cell lineage of the terrestrial nematode, Halicephalobus gingivalis, up to somatic muscle contraction, resulting in the formation of 536 cells, of which 24 undergo programmed cell death. Halicephalobus gingivalis has a 94% lineage homology with both Caenorhabditis elegans and Pellioditis marina, and a fate homology of only 86% and 78%, respectively. Although H. gingivalis belongs to a different superfamily than C. elegans and P. marina, its cell lineage is remarkably consistent with them. Variations in the fate distribution of cells among the different species were only observed at the end of the cell lineage. The data presented here show that the polyclonal cell specification is much more widespread in clades 9 and 10 and is not a highly derived trait that is specifically linked to the fast development of the model organism C. elegans.

Resolving phylogenetic incongruence to articulate homology and phenotypic evolution: a case study from Nematoda

“…For example, the lack of eutely (cell constancy) in many organisms may preclude developmental similarity in homology criteria in the study of individual cells, although cell or tissue topology regardless of ontogenetic lineage may still serve to pinpoint the locus of homology (de Beer 1971;Wagner & Misof 1993;Hall 1994;Bolker & Raff 1996;Mü ller 2003). Even between nematodes with divergent but determinate cell lineages, lineally non-homologous cells are in some cases locally induced to form tissue with comparable cell composition (Houthoofd et al 2003;Houthoofd & Borgonie 2007). Similarity is still manifest as an end product.…”

“…The constancy in cell number and patterns of cell divisions in Order Rhabditida (Sulston et al 1983;Houthoofd et al 2003;Houthoofd & Borgonie 2007) facilitates comparison of individually homologous cells across broader taxa (Fitch 1997;Félix et al 2000). Furthermore, the limited size of nematodes makes complete, three-dimensional reconstruction of entire organ systems a feasible goal.…”

Developmental motifs reveal complex structure in cell lineages

“…We computed additional profiles using deeper motifs [Figure 4(A)], motifs distinguished on the basis of cell type [i.e., typological as well as topological patterns, Figure 4(B) – triangles], and motifs that ignore the orientation of cell division [such that isomorphic motifs were merged, Figure 4(B) – crosses]. We also computed the motif profiles of two other nematode lineages, Pellioditis marina [19] and Halicephalobus gingivalis [20] [Figure 4(C)]. In all cases, although minor differences were observed, the general shape of the motif profile is preserved.…”

“…One class of complex biological system for which we do have rich data sets is nematode development. The developmental trajectories of several nematodes, such as Caenorhabditis elegans , are invariant and have been mapped in considerable detail in the form of cell lineages [19–22]. A cell lineage is a schematic representation of a developmental process that describes the ancestry of all cells generated during an organism's development in terms of patterns of division and differentiation events.…”

The embryonic cell lineage of the nematode Rhabditophanes sp.

“…To examine the extent of conservation of this mode of development in nematodes, we established the embryonic cell lineages of more distantly related nematodes from the adjacent clade IV. Recently, we determined the embryonic cell lineage of Halicephalobus gingivalis (Houthoofd and Borgonie, 2007). Here we present the nearly complete embryonic cell lineage of the free-living nematode Rhabditophanes sp.…”