Expression of pair-rule gene homologues in a chelicerate: Early patterning of two-spotted spider mite Tetranychus urticae
- Dearden, P.K. 123
- Donly, C. 3
- Grbić, M. 2
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1
University of Otago
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2
University of Western Ontario
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- 3 Southern Crop Prot./Food Res. Center, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, Ont. N5V 4T3, Canada
ISSN: 0950-1991
Año de publicación: 2002
Volumen: 129
Número: 23
Páginas: 5461-5472
Tipo: Artículo
Otras publicaciones en: Development
Resumen
Embryo segmentation has been studied extensively in the fruit fly, Drosophila. These studies have demonstrated that a mechanism acting with dual segment periodicity is required for correct patterning of the body plan in this insect, but the evolutionary origin of the mechanism, the pair-rule system, is unclear. We have examined the expression of the homologues of two Drosophila pair-rule genes, runt and paired (Pax Group III), in segmenting embryos of the two-spotted spider mite (Tetranychus urticae Koch). Spider mites are chelicerates, a group of arthropods that diverged from the lineage leading to Drosophila at least 520 million years ago. In T. urticae, the Pax Group III gene Tu-pax3/7 was expressed during patterning of the prosoma, but not the opisthosoma, in a series of stripes which appear first in even numbered segments, and then in odd numbered segments. The mite runt homologue (Tu-run) in contrast was expressed early in a circular domains that resolved into a segmental pattern. The expression patterns of both of these genes also indicated they are regulated very differently from their Drosophila homologues. The expression pattern of Tu-pax3/7 lends support to the possibility that a pair-rule patterning mechanism is active in the segmentation pathways of chelicerates.