Figure 1.
Phylogenetic position of Heterorhabditis relative to other notable Rhabditina.
A. At the base of the tree is the free-living microbivorous Panagrellus (Panagrolaimoidea). Lineages in green are semaphoronts of large, diverse clades of microbivorous nematodes whose members associate with invertebrates at some point in their lifecycle, typically via phoresy and/or necromeny [52]–[54]. Heterorhabditis is a transitional taxon, exhibiting ancestral microbivorous traits, but has also evolved obligate pathenogensis and shares most recent common ancestry with obligate mammalian parasites (Strongyloidea; lineages in red). Modified after [127]–[129]. Taxonomy follows the ranking hypotheses and nomenclature of Hodda, 2011 [130]. B. H. bacteriophora nematodes have evolved a mutualism with insect pathogenic P. luminescens bacteria (green) where each partner cooperates to achieve voracious entomopathogenicity. An infective juvenile regurgitating intestinal symbionts (right) out the pharynx is shown. The movement of the nematode head causes slight misalignment of the fluorescent and differential interference micrograph image overlays.
Table 1.
Comparison of Heterorhabditis bacteriophora genome with the complete genome of Caenorhabditis elegans (WS220) and the draft genomes of Meloidogyne hapla [132] and Brugia malayi [87].
Figure 2.
Genes of insulin/IGF-1 signaling pathway in H. bacteriophora (highlighted in yellow) and C. elegans (all genes).
The genes in red and blue fonts are negative regulator and positive regulator, respectively, of stress resistance, lifespan, and immunity in C. elegan [131].
Figure 3.
Comparison of genes involved in RNA interference pathway in C. elegans, B. malayi, M. hapla, and H. bacteriophora.
Four genes in bold, drsh-1, ego-1, rsd-3, and smg-2 were identified in all four species. sid-1 gene that is required for systemic RNAi in C. elegans was only identified in C. elegans and H. bacteriophora.
Figure 4.
Comparison of top 20 Pfam domains in H. bacteriophora genome with those in the 10 nematode species in the study.
The top 20 Pfam domains were identified as the ones having the 20 largest number of occurrence in H. bacteriophora genome.
Table 2.
Numbers of mariner type motifs in H. bacteriophora and C. elegans genomes.
Table 3.
Summary of secreted peptidases and peptidase inhibitors identified in H. bacteriophora.
Table 4.
Genes and KEGG orthology (KO) in metabolic pathways in selected nematode species with different life styles.
Figure 5.
H. bacteriophora informs C. elegans protein structure function.
Multiple alignment of the EGF-receptor (LET-23) carboxyl tail of Caenorhabditis elegans, briggsae and japonica with H. bacteriophora. 3-way, alignment of the three Caenorhabditis proteins; 4-way, alignment of three Caenorhabditis proteins with Hba-LET-23. *, identity; :, strong similarity; ., weak similarity. Red and green highlight the parts of the protein that have been demonstrated to be important in signaling and localization, respectively. Numbers represent the length of the predicted proteins.