Spatiotemporal variation in cell proliferation patterns during arthropod axial elongation

Abstract

An elongated and segmented body plan is a common morphological characteristic of all arthropods and is probably responsible for their high adaptation ability to diverse environments. Most arthropods form their bodies by progressively adding segments, resembling vertebrate somitogenesis. This sequential segmentation relies on a molecular clock that operates in the posterior region of the elongating embryo that combines dynamically with cellular behaviors and tissue rearrangements, allowing the extension of the developing body along its main embryonic axis. Even though the molecular mechanisms involved in elongation and segment formation have been found to be conserved in a considerable degree, cellular processes such as cell division are quite variable between different arthropods. In this study, we show that cell proliferation in the beetle Tribolium castaneum has a nonuniform spatiotemporal patterning during axial elongation. We found that dividing cells are preferentially oriented along the anterior–posterior axis, more abundant and posteriorly localized during thoracic segments formation and that this cell proliferation peak was triggered at the onset of axis elongation. This raise in cell divisions, in turn, was correlated with an increase in the elongation rate, but not with changes in cell density. When DNA synthesis was inhibited over this period, both the area and length of thoracic segments were significantly reduced but not of the first abdominal segment. We discuss the variable participation that different cell division patterns and cell movements may have on arthropod posterior growth and their evolutionary contribution.

The organizing role of Wnt signaling pathway during arthropod posterior growth

“…A similar correlation was found in Oncopeltus , where the region of cell divisions coincides with the expression of Of-eve and Of-caudal genes, two targets of Wnt signaling. The proposed model differs, however, from what was found in Dermestes (Xiang et al, 2017) and Tribolium (Cepeda et al, 2021). The proliferation region is not temporally stable in these beetles, but variable and posteriorly concentrated at specific stages.…”

Patterning with clocks and genetic cascades: Segmentation and regionalization of vertebrate versus insect body plans

“…Therefore, the terms “short-germ insects” and “long-germ insects” are sometimes used synonymously with “sequentially segmenting insects” and “simultaneously segmenting insects,” respectively. Axis elongation of insect germ-bands is driven by convergent extension and/or cell proliferation [ 7 , 54 – 59 ].…”