Abstract

One of the conserved traits of arthropod embryonic development is striped expression of homologs of Drosophila segment polarity genes, including hedgehog (hh), which is the outcome of segmentation. Despite this conservation, processes leading to the stripes are recognized as diversified among arthropod embryos. However, such varied stripe-forming processes have not been well characterized from cellular, quantitative, and systems perspectives. In this talk, we show that the spider Parasteatoda tepidariorum model system offers a cell-based field where the stripe-forming processes exhibit distinct dynamic waves, oscillatory/non-oscillatory traveling waves and bi-/tri-splitting waves, among the presumptive head, thoracic, and opisthosomal (abdominal) regions of the field undergoing axis formation and growth. We find that formation of a global anterior-posterior polarity in the spider embryo relies on Hh signaling and that this Hh signaling controls segmentation dynamics and diversity in the field via a specific transcription factor gene. Our findings highlight the major contribution of a Hh signaling network to segmentation in an arthropod cell-based field, providing an example of an evolvable patterning system that is comparable to the vertebrate appendage with repetitive elements relying on Hh signaling.