| المؤلفون: |
Nakamoto A; Molecular and Cellular Biology, Life Sciences South, 1007 E. Lowell, Tucson, Arizona 85721, USA., Hester SD; Molecular and Cellular Biology, Life Sciences South, 1007 E. Lowell, Tucson, Arizona 85721, USA., Constantinou SJ; Department of Biology, Life Sciences Center, Trinity College, 300 Summit Street, Hartford, Connecticut 06106, USA., Blaine WG; Department of Biology, Life Sciences Center, Trinity College, 300 Summit Street, Hartford, Connecticut 06106, USA., Tewksbury AB; Department of Biology, Life Sciences Center, Trinity College, 300 Summit Street, Hartford, Connecticut 06106, USA., Matei MT; Molecular and Cellular Biology, Life Sciences South, 1007 E. Lowell, Tucson, Arizona 85721, USA., Nagy LM; Molecular and Cellular Biology, Life Sciences South, 1007 E. Lowell, Tucson, Arizona 85721, USA., Williams TA; Department of Biology, Life Sciences Center, Trinity College, 300 Summit Street, Hartford, Connecticut 06106, USA. |
| مستخلص: |
Segmented animals are found in major clades as phylogenetically distant as vertebrates and arthropods. Typically, segments form sequentially in what has been thought to be a regular process, relying on a segmentation clock to pattern budding segments and posterior mitosis to generate axial elongation. Here we show that segmentation in Tribolium has phases of variable periodicity during which segments are added at different rates. Furthermore, elongation during a period of rapid posterior segment addition is driven by high rates of cell rearrangement, demonstrated by differential fates of marked anterior and posterior blastoderm cells. A computational model of this period successfully reproduces elongation through cell rearrangement in the absence of cell division. Unlike current models of steady-state sequential segmentation and elongation from a proliferative growth zone, our results indicate that cell behaviours are dynamic and variable, corresponding to differences in segmentation rate and giving rise to morphologically distinct regions of the embryo. |
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