From DNA to Diversity by Grenier Jennifer Weatherbee Scott Carroll Sean B. & Jennifer K. Grenier & Scott D. Weatherbee

Author:Grenier, Jennifer, Weatherbee, Scott, Carroll, Sean B. & Jennifer K. Grenier & Scott D. Weatherbee
Language: eng
Format: epub
Publisher: Wiley
Published: 2013-04-15T16:00:00+00:00

Evolution of the genetic control of segmentation in arthropods

Underlying the general similarity of arthropod segmentation are conserved gene expression patterns, which suggests that there may be a common regulatory program for segmentation among arthropods. For example, segmentation in all classes—insects, crustaceans, myriapods, and chelicerates—passes through a stage when the engrailed gene is expressed in a stripe in each segment (Fig. 5.1). In Drosophila , this segment polarity gene—a member of the last tier in the segmentation gene cascade—functions to establish and maintain compartmental and segmental boundaries. In addition, a number of other genes involved in Drosophila segmentation, including even-skipped, hairy, wingless, and runt, are expressed in patterns that appear to be associated with segmentation in several insects, crustaceans, centipedes, and spiders. Thus, some of the members in the Drosophila segmentation cascade appear to be deployed among most arthropods during the segmentation process. However, a number of striking differences are also apparent. These may be related to the differences in early embryonic development between arthropods. In Drosophila, segmentation depends on gradients of transcription factor activity in a syncytial embryo; in other arthropods, segmentation occurs over a longer period in a cellularized embryo.

Figure 5.1 Conservation of segmental engrailed expression in arthropods All arthropods share a segmented body plan. (a) The phylogeny of major arthropod groups is shown with representative animals. (b) The engrailed segment polarity gene is expressed in segmentally iterated stripes during embryogenesis in different arthropods. This similarity indicates that segmental engrailed expression is a conserved stage in the development of all arthropods.

Source: Part b from Patel NH. The evolution of arthropod segmentation: insights from comparisons of gene expression patterns. Development 1994(suppl): 201–207; Telford MJ, Thomas RH. Proc Natl Acad Sci USA 1998; 95: 10671–10675; Hughes CL, Kaufman, TC. Dev Biol 2002; 247: 47–61. Copyright (2002), reprinted with permission from Elsevier.

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