A comprehensive study of arthropod and onychophoran Fox gene expression patterns

Abstract

Fox genes represent an evolutionary old class of transcription factor encoding genes that evolved in the last common ancestor of fungi and animals. They represent key-components of multiple gene regulatory networks (GRNs) that are essential for embryonic development. Most of our knowledge about the function of Fox genes comes from vertebrate research, and for arthropods the only comprehensive gene expression analysis is that of the fly Drosophila melanogaster. For other arthropods, only selected Fox genes have been investigated. In this study, we provide the first comprehensive gene expression analysis of arthropod Fox genes including representative species of all main groups of arthropods, Pancrustacea, Myriapoda and Chelicerata. We also provide the first comprehensive analysis of Fox gene expression in an onychophoran species. Our data show that many of the Fox genes likely retained their function during panarthropod evolution highlighting their importance in development. Comparison with published data from other groups of animals shows that this high degree of evolutionary conservation often dates back beyond the last common ancestor of Panarthropoda.

Unfolding the ventral nerve center of chaetognaths

“…In S. cephaloptera hatchlings, foxA-expression is also observed in various parts of the digestive tract, particularly in cells lining the foregut, corroborating its conserved regulatory functions during bilaterian digestive tract formation and regionalization [81]. Moreover, Sce-foxA-expression is also detected in the developing brain and the VNC, which resembles the condition in annelids [67][68][69] and ecdysozoans [74,82,83]. While some annelids probably express foxA in the ventral neuroectoderm, foxA is expressed in the floor plate of the developing neural tube of chordates [80,[84][85][86][87].…”

“…FoxA is expressed in the foregut of the mollusks Patella vulgata [65] and Crepidula fornicata [66], in the ectodermal foregut and hindgut of annelids [67][68][69][70] and the planarians Dugesia japonica [71] and Schmidtea polychroa [72]. In addition, expression of foxA in the pharynx has also been reported for Phoronida [73], Ecdysozoa [74][75][76][77], and Chordata [78][79][80]. In S. cephaloptera hatchlings, foxA-expression is also observed in various parts of the digestive tract, particularly in cells lining the foregut, corroborating its conserved regulatory functions during bilaterian digestive tract formation and regionalization [81].…”

Single-cell RNA sequencing of mid-to-late stage spider embryos: new insights into spider development

“…[ 78 , 146 ]. A recent study has shown that in Parasteatoda , FoxF1 is almost exclusively expressed in the visceral mesoderm of the opisthosoma [ 89 ].…”

“…The only previously investigated spider genes that represent markers of Cluster-XXII are the two forkhead domain transcription factors FoxC / crocodile ( croc ) (LOC107456536) and FoxA / forkhead ( fkh ) (LOC107452746), six3 (LOC107450741), and visual system homeobox ( vsx ) (LOC122268388). In Parasteatoda and other spiders, these genes are expressed in the stomodaeum and along the split ventral midline [ 84 , 89 , 111 , 163 ]. Expression of unc5848 , unc3843 , and anapece , however, shows that these top markers are expressed exclusively in the stomodaeum, or strongly in the stomodaeum and faintly at the edges of the split ventral midline (Fig.…”

“…In order to investigate genes (and thus gene regulatory networks) beyond the classic candidate gene approach, genomics and embryonic and tissue-specific transcriptomics have been applied in the recent past, leading to the investigation of complete gene families, orphan genes, fast evolving genes and tissue-specific genes (e.g. [ 20 , 77 , 89 , 142 , 155 ]. A relatively recent new technical innovation now allows investigation of the transcriptome of every cell of a given organism or a developmental stage of a given organism separately.…”