Composition and genomic organization of arthropod Hox clusters

Ryan M. Pace, Miodrag Grbić, Lisa M Nagy

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Background: The ancestral arthropod is believed to have had a clustered arrangement of ten Hox genes. Within arthropods, Hox gene mutations result in transformation of segment identities. Despite the fact that variation in segment number/character was common in the diversification of arthropods, few examples of Hox gene gains/losses have been correlated with morphological evolution. Furthermore, a full appreciation of the variation in the genomic arrangement of Hox genes in extant arthropods has not been recognized, as genome sequences from each major arthropod clade have not been reported until recently. Initial genomic analysis of the chelicerate Tetranychus urticae suggested that loss of Hox genes and Hox gene clustering might be more common than previously assumed. To further characterize the genomic evolution of arthropod Hox genes, we compared the genomic arrangement and general characteristics of Hox genes from representative taxa from each arthropod subphylum. Results: In agreement with others, we find arthropods generally contain ten Hox genes arranged in a common orientation in the genome, with an increasing number of sampled species missing either Hox3 or abdominal-A orthologs. The genomic clustering of Hox genes in species we surveyed varies significantly, ranging from 0.3 to 13.6 Mb. In all species sampled, arthropod Hox genes are dispersed in the genome relative to the vertebrate Mus musculus. Differences in Hox cluster size arise from variation in the number of intervening genes, intergenic spacing, and the size of introns and UTRs. In the arthropods surveyed, Hox gene duplications are rare and four microRNAs are, in general, conserved in similar genomic positions relative to the Hox genes. Conclusions: The tightly clustered Hox complexes found in the vertebrates are not evident within arthropods, and differential patterns of Hox gene dispersion are found throughout the arthropods. The comparative genomic data continue to support an ancestral arthropod Hox cluster of ten genes with a shared orientation, with four Hox gene-associated miRNAs, although the degree of dispersion between genes in an ancestral cluster remains uncertain. Hox3 and abdominal-A orthologs have been lost in multiple, independent lineages, and current data support a model in which inversions of the Abdominal-B locus that result in the loss of abdominal-A correlate with reduced trunk segmentation.

Original languageEnglish (US)
Article number11
JournalEvoDevo
Volume7
Issue number1
DOIs
StatePublished - May 10 2016

Fingerprint

Arthropods
Homeobox Genes
arthropod
arthropods
genomics
gene
genes
Genome
MicroRNAs
multigene family
genome
Cluster Analysis
Vertebrates
vertebrates
vertebrate
Untranslated Regions
Gene Duplication
Tetranychus urticae
Mus musculus
gene duplication

Keywords

  • Arthropod
  • Chelicerate
  • Daphnia
  • Development
  • Evolution
  • Hox
  • Ixodes
  • Segmentation
  • Tetranychus

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Ecology, Evolution, Behavior and Systematics

Cite this

Composition and genomic organization of arthropod Hox clusters. / Pace, Ryan M.; Grbić, Miodrag; Nagy, Lisa M.

In: EvoDevo, Vol. 7, No. 1, 11, 10.05.2016.

Research output: Contribution to journalArticle

Pace, Ryan M. ; Grbić, Miodrag ; Nagy, Lisa M. / Composition and genomic organization of arthropod Hox clusters. In: EvoDevo. 2016 ; Vol. 7, No. 1.
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