Buccal capsule development as a consideration for phylogenetic analysis of Rhabditida (Nemata)

Abstract

Bacterial feeding nematodes in the order Rhabditida including Zeldia punctata (Cephalobidae) and Caenorhabditis elegans (Rhabditidae) differ profoundly in the buccal capsule parts and associated cells. We carried out a range of tests to determine which buccal capsule parts and cells are evolutionarily homologous between the representative species of the two families. Tests included reconstruction of the buccal capsule and procorpus with transmission electron microscopy (TEM), nuclei position and morphology using 4, 6-diamidino-2-phenylindole (DAPI) staining, and cell lineage using four dimensional (4D) microscopy. The lining of the buccal capsule of Z. punctata and additional Cephalobidae includes four sets of muscular radial cells, ma, mb, mc and md, in contrast to C. elegans and additional Rhabditidae, which has two sets of epithelial cells (e1, e3) and two sets of muscle cells (m1, m2). Cell lineage of a nematode closely related to Z. punctata, Cephalobus cubaensis, supports the hypothesis that in cephalobids the e1 and e3 cells become hypodermal cells or are programmed to die. Our findings contradict all previous hypotheses of buccal capsule homology, and suggest instead that ma and mb in Z. punctata are homologous to m1 and m2 in C. elegans respectively. We also hypothesize that ma and mb could be homologous to primary and secondary sets of stylet-protractor muscle cells in the plant parasitic Tylenchida.

The eutardigradeThulinia stephaniaehas an indeterminate development and the potential to regulate early blastomere ablations

“…(Schnabel et al, 1997), which allows us to follow cells in the living embryo. This new technology has been successfully used for studies of nematode embryos (Dolinski et al, 1998;Houthoofd et al, 2003;Schnabel et al, 1997), the analysis of brain development in Drosophila (Urbach et al, 2003), and description of segmentation in an isopod crustacean (A. Hejnol, PhD thesis, Humboldt University of Berlin, 2002) (Dohle et al, 2004). To further investigate the type of determination and the potential for regulation of the tardigrade embryo, we combined 4D-microscopy with laser cell ablations.…”

Ultrastructure of the post–corpus of Zeldia punctata (Cephalobina) for analysis of the evolutionary framework of nematodes related to Caenorhabditis elegans (Rhabditina)

“…This problem has been underscored since the application of TEM in rede¢ning previously misinterpreted characters of the buccal capsule (Baldwin & Eddleman 1995;De Ley et al 1995;Baldwin et al 1997b;Dolinski et al 1998). …”

Three‐dimensional reconstruction of the nose epidermal cells in the microbial feeding nematode, Acrobeles complexus (Nematoda: Rhabditida)

“…It is noteworthy that the two taxa, although not closely related, share many ancestral attributes in their feeding morphologies (Van de Velde et al, 1994;Dolinski et al, 1998;Zhang and Baldwin, 2001). The cuticle of the nose region in the Cephalobina can be modified into elaborate appendages, probolae ( Fig.…”