scholarly journals Development of the Pre-gnathal Segments in the Milkweed Bug Oncopeltus fasciatus Suggests They Are Not Serial Homologs of Trunk Segments

2021 ◽  
Vol 9 ◽  
Author(s):  
Oren Lev ◽  
Ariel D. Chipman
Keyword(s):  
Rna Interference ◽  
Gene Function ◽  
Expression Patterns ◽  
Developmental Differences ◽  
Oncopeltus Fasciatus ◽  
Segment Polarity Genes ◽  
Hemimetabolous Insect ◽  
Segment Polarity ◽  
And Function ◽  
Trunk Segments

The three anterior-most segments in arthropods contain the ganglia that make up the arthropod brain. These segments, the pre-gnathal segments (PGS), are known to exhibit many developmental differences to other segments, believed to reflect their divergent morphology. We have analyzed the expression and function of the genes involved in the conserved segment-polarity network, including genes from the Wnt and Hedgehog pathways, in the PGS, compared with the trunk segments, in the hemimetabolous insect Oncopeltus fasciatus. Gene function was tested by manipulating expression through RNA interference against components of the two pathways. We show that there are fundamental differences in the expression patterns of the segment polarity genes, in the timing of their expression and in the interactions among them in the process of pre-gnathal segment generation, relative to all other segments. We argue that given these differences, the PGS should not be considered serially homologous to trunk segments. This realization raises important questions about the differing evolutionary ancestry of different regions of the arthropod head.

scholarly journals Development of the Pre-Gnathal Segments of the Insect Head Indicates They Are Not Serial Homologues of Trunk Segments

2020 ◽  
Author(s):  
Oren Lev ◽  
Ariel D. Chipman
Keyword(s):  
Fossil Record ◽  
Developmental Differences ◽  
Oncopeltus Fasciatus ◽  
Arthropod Evolution ◽  
Hemimetabolous Insect ◽  
Segment Polarity ◽  
And Function ◽  
Trunk Segments ◽  
The Way

AbstractThe three anterior-most segments in arthropods contain the ganglia that make up the arthropod brain. These segments, the pre-gnathal segments, are known to exhibit many developmental differences to other segments, believed to reflect their divergent morphology. We have analyzed the expression and function of the genes involved in the segment-polarity network in the pre-gnathal segments compared with the trunk segments in the hemimetabolous insect Oncopeltus fasciatus. We show that there are fundamental differences in the way the pre-gnathal segments are generated and patterned, relative to all other segments, and that these differences are general to all arthropods. We argue that given these differences, the pre-gnathal segments should not be considered serially homologous to trunk segments. This realization has important implications for our understanding of the evolution of the arthropod head. We suggest a novel scenario for arthropod head evolution that posits duplication of an ancestral single-segmented head into three descendent segments. This scenario is consistent with what we know of head evolution from the fossil record, and helps reconcile some of the debates about early arthropod evolution.

scholarly journals Studying the effect of cell division on expression patterns of the segment polarity genes

2008 ◽  
Vol 5 (suppl_1) ◽  
Author(s):  
Madalena Chaves ◽  
Réka Albert
Keyword(s):  
Cell Division ◽  
Expression Patterns ◽  
Gene Expression Pattern ◽  
Specific Gene ◽  
Biological Processes ◽  
Segment Polarity Genes ◽  
Genes Expression ◽  
Its Gene ◽  
Segment Polarity ◽  
Segment Polarity Gene

The segment polarity gene family, and its gene regulatory network, is at the basis of Drosophila embryonic development. The network's capacity for generating and robustly maintaining a specific gene expression pattern has been investigated through mathematical modelling. The models have provided several useful insights by suggesting essential network links, or uncovering the importance of the relative time scales of different biological processes in the formation of the segment polarity genes' expression patterns. But the developmental pattern formation process raises many other questions. Two of these questions are analysed here: the dependence of the signalling protein sloppy paired on the segment polarity genes and the effect of cell division on the segment polarity genes' expression patterns. This study suggests that cell division increases the robustness of the segment polarity network with respect to perturbations in biological processes.

scholarly journals Growth zone segmentation in the milkweed bug Oncopeltus fasciatus sheds light on the evolution of insect segmentation

2018 ◽  
Author(s):  
Tzach Auman ◽  
Ariel D. Chipman
Keyword(s):  
Gene Expression ◽  
Growth Zone ◽  
Oncopeltus Fasciatus ◽  
Milkweed Bug ◽  
Segment Polarity Genes ◽  
Temporal Relationships ◽  
Segment Polarity ◽  
Spatio Temporal ◽  
Segment Pattern ◽  
Pair Rule

AbstractOne of the best studied developmental processes is the Drosophila segmentation cascade. However, this cascade is generally considered to be highly derived and unusual. We present a detailed analysis of the sequential segmentation cascade of the milkweed bug Oncopletus fasciatus, as a comparison to Drosophila, with the aim of reconstructing the evolution of insect segmentation. We analyzed the expression of 12 genes, representing different phases during segmentation. We reconstruct the spatio-temporal relationships among these genes And their roles and position in the cascade. We conclude that sequential segmentation in the Oncopeltus germband includes three phases: Primary pair-rule genes generate segmental gene expression in the anterior growth zone, followed by secondary pair-rule genes, expressed in the transition between the growth zone and the segmented germband. Segment polarity genes are expressed in the segmented germband. This process generates a single-segment periodicity, and does not have a double-segment pattern at any stage.

Pax group III genes and the evolution of insect pair-rule patterning

Development ◽  
2001 ◽  
Vol 128 (18) ◽  
pp. 3445-3458 ◽  
Author(s):  
Gregory K. Davis ◽  
Carlos A. Jaramillo ◽  
Nipam H. Patel
Keyword(s):  
Protein Pattern ◽  
Expression Patterns ◽  
Group Iii ◽  
Variable Expression ◽  
Flour Beetles ◽  
Process Understanding ◽  
Hemimetabolous Insect ◽  
Segment Polarity ◽  
Early Expression ◽  
Pair Rule

Pair-rule genes were identified and named for their role in segmentation in embryos of the long germ insect Drosophila. Among short germ insects these genes exhibit variable expression patterns during segmentation and thus are likely to play divergent roles in this process. Understanding the details of this variation should shed light on the evolution of the genetic hierarchy responsible for segmentation in Drosophila and other insects. We have investigated the expression of homologs of the Drosophila Pax group III genes paired, gooseberry and gooseberry-neuro in short germ flour beetles and grasshoppers. During Drosophila embryogenesis, paired acts as one of several pair-rule genes that define the boundaries of future parasegments and segments, via the regulation of segment polarity genes such as gooseberry, which in turn regulates gooseberry-neuro, a gene expressed later in the developing nervous system. Using a crossreactive antibody, we show that the embryonic expression of Pax group III genes in both the flour beetle Tribolium and the grasshopper Schistocerca is remarkably similar to the pattern in Drosophila. We also show that two Pax group III genes, pairberry1 and pairberry2, are responsible for the observed protein pattern in grasshopper embryos. Both pairberry1 and pairberry2 are expressed in coincident stripes of a one-segment periodicity, in a manner reminiscent of Drosophila gooseberry and gooseberry-neuro. pairberry1, however, is also expressed in stripes of a two-segment periodicity before maturing into its segmental pattern. This early expression of pairberry1 is reminiscent of Drosophila paired and represents the first evidence for pair-rule patterning in short germ grasshoppers or any hemimetabolous insect.

scholarly journals Shifting roles of Drosophila pair-rule gene orthologs: segmental expression and function in the milkweed bug Oncopeltus fasciatus

2019 ◽  
Author(s):  
Katie Reding ◽  
Mengyao Chen ◽  
Yong Lu ◽  
Alys M. Cheatle Jarvela ◽  
Leslie Pick
Keyword(s):  
Oncopeltus Fasciatus ◽  
Regulatory Pathways ◽  
Milkweed Bug ◽  
Regulatory Circuits ◽  
Hemimetabolous Insect ◽  
Pair Rule Gene ◽  
Summary Statement ◽  
And Function ◽  
Gene Orthologs ◽  
Pair Rule

AbstractThe discovery of pair-rule genes (PRGs) in Drosophila revealed the existence of an underlying two-segment-wide prepattern directing embryogenesis. The milkweed bug Oncopeltus, a hemimetabolous insect, is a more representative arthropod: most of its segments form sequentially after gastrulation. Here we report the expression and function of orthologs of the complete set of nine Drosophila PRGs in Oncopeltus. Seven Of-PRG-orthologs are expressed in stripes in the primordia of every segment, rather than every-other segment, Of-runt is PR-like, and several are also expressed in the segment addition zone. RNAi-mediated knockdown of Of-odd-skipped, paired and sloppy-paired impacted all segments, with no indication of PR-like register. We confirm that Of-E75A is expressed in PR-like stripes, although it is not PR in Drosophila, demonstrating the existence of an underlying PR-like prepattern in Oncopeltus. These findings reveal that a switch occurred in regulatory circuits leading to segment formation: while several holometabolous insects are “Drosophila-like,” utilizing PRG-orthologs for PR-patterning, most Of-PRGs are expressed segmentally in Oncopeltus, a more basally-branching insect. Thus, an evolutionarily stable phenotype – segment formation – is directed by alternate regulatory pathways in diverse species.Summary StatementDespite the broad of conservation of segmentation in insects, the regulatory genes underlying this process in Drosophila have different roles in the hemipteran, Oncopeltus fasciatus.

A role for En-2 and other murine homologues of Drosophila segment polarity genes in regulating positional information in the developing cerebellum

Development ◽  
1995 ◽  
Vol 121 (12) ◽  
pp. 3935-3945 ◽  
Author(s):  
K.J. Millen ◽  
C.C. Hui ◽  
A.L. Joyner
Keyword(s):  
Spatial Information ◽  
Expression Patterns ◽  
Molecular Genetic ◽  
Gene Families ◽  
Positional Information ◽  
Spatial Cues ◽  
Segment Polarity Genes ◽  
Segment Polarity ◽  
Developing Cerebellum ◽  
Anterior Posterior

To gain insight into the molecular genetic basis of cerebellar patterning, the expression patterns of many vertebrate homologues of Drosophila segment polarity genes were examined during normal and abnormal cerebellar development, including members of the En, Wnt, Pax, Gli and Dvl gene families. Five of these genes were found to show transient, spatially restricted patterns of expression. Strikingly, expression of En-2, En-1, Wnt-7B and Pax-2 defined eleven similar sagittal domains at 17.5 dpc, reminiscent of the transient sagittal domains of expression of Purkinje cell markers which have been implicated in cerebellar afferent patterning. Postnatally, transient anterior/posterior differences in expression were observed for En-2, En-1, Gli and Wnt-7B dividing the cerebellum into anterior and posterior regions. The expression patterns of these genes were altered in cerebella of En-2 homozygous mutant mice, which show a cerebellar foliation patterning defect. Strikingly, four of the Wnt-7B expression domains that are adjacent to the En-2 domains are lost in En-2 mutant embryonic cerebella. These studies provide the first evidence of a potential network of regulatory genes that establish spatial cues in the developing cerebellum by dividing it into a grid of positional information required for patterning foliation and afferents. Taken together with previous gene expression studies, our data suggests that eleven sagittal domains and at least two anterior/posterior compartments are the basic elements of spatial information in the cerebellum.

scholarly journals Analysis of maxillopedia Expression Pattern and Larval Cuticular Phenotype in Wild-Type and Mutant Tribolium

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 721-731 ◽  
Author(s):  
Teresa D Shippy ◽  
Jianhua Guo ◽  
Susan J Brown ◽  
Richard W Beeman ◽  
Robin E Denell
Keyword(s):  
Rna Interference ◽  
Expression Pattern ◽  
Tribolium Castaneum ◽  
Expression Patterns ◽  
Ectopic Expression ◽  
Homeotic Gene ◽  
Wild Type ◽  
Double Stranded Rna ◽  
Similar Expression ◽  
Mutant Phenotypes

Abstract The Tribolium castaneum homeotic gene maxillopedia (mxp) is the ortholog of Drosophila proboscipedia (pb). Here we describe and classify available mxp alleles. Larvae lacking all mxp function die soon after hatching, exhibiting strong transformations of maxillary and labial palps to legs. Hypomorphic mxp alleles produce less severe transformations to leg. RNA interference with maxillopedia double-stranded RNA results in phenocopies of mxp mutant phenotypes ranging from partial to complete transformations. A number of gain-of-function (GOF) mxp alleles have been isolated based on transformations of adult antennae and/or legs toward palps. Finally, we have characterized the mxp expression pattern in wild-type and mutant embryos. In normal embryos, mxp is expressed in the maxillary and labial segments, whereas ectopic expression is observed in some GOF variants. Although mxp and Pb display very similar expression patterns, pb null embryos develop normally. The mxp mutant larval phenotype in Tribolium is consistent with the hypothesis that an ancestral pb-like gene had an embryonic function that was lost in the lineage leading to Drosophila.

Sign in / Sign up

Export Citation Format

Share Document