title: even-skipped has gap-like, pair-rule-like, and segmental functions in the cricket Gryllus bimaculatus, a basal, intermediate germ insect (Orthoptera).
abstract: Developmental mechanisms of segmentation appear to be varied among insects in spite of their conserved body plan. Although the expression patterns of the segment polarity genes in all insects examined imply well conserved function of this class of genes, expression patterns and function of the pair-rule genes tend to exhibit diversity. To gain further insights into the evolution of the segmentation process and the role of pair-rule genes, we have examined expression and function of an ortholog of the Drosophila pair-rule gene even-skipped (eve) in a phylogenetically basal insect, Gryllus bimaculatus (Orthoptera, intermediate germ cricket). We find that Gryllus eve (Gb'eve) is expressed as stripes in each of the prospective gnathal, thoracic, and abdominal segments and as a broad domain in the posterior growth zone. Dynamics of stripe formation vary among Gb'eve stripes, representing one of the three modes, the segmental, incomplete pair-rule, and complete pair-rule mode. Furthermore, we find that RNAi suppression of Gb'eve results in segmentation defects in both anterior and posterior regions of the embryo. Mild depletion of Gb'eve shows a pair-rule-like defect in anterior segments, while stronger depletion causes a gap-like defect showing deletion of anterior and posterior segments. These results suggest that Gb'eve acts as a pair-rule gene at least during anterior segmentation and also has segmental and gap-like functions. Additionally, Gb'eve may be involved in the regulation of hunchback and Krüppel expression. Comparisons with eve functions in other species suggest that the Gb'eve function may represent an intermediate state of the evolution of pair-rule patterning by eve in insects.
authors.affiliation: Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City 770-8506, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Mito
authors.forename: Chiharu
authors.initials: C
authors.lastname: Kobayashi
authors.forename: Isao
authors.initials: I
authors.lastname: Sarashina
authors.forename: Hongjie
authors.initials: H
authors.lastname: Zhang
authors.forename: Wakako
authors.initials: W
authors.lastname: Shinahara
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Miyawaki
authors.forename: Yohei
authors.initials: Y
authors.lastname: Shinmyo
authors.forename: Hideyo
authors.initials: H
authors.lastname: Ohuchi
authors.forename: Sumihare
authors.initials: S
authors.lastname: Noji
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000235:genetics*; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006135:Gryllidae / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010802:Phylogeny; D034622:RNA Interference; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D014157:Transcription Factors