Upregulation of E93 gene expression acts as the trigger for metamorphosis independently of the threshold Size in the Beetle Tribolium castaneum
In the present study, Chafino et al. identify the upregulation of E93 expression as the trigger for metamorphosis in the holometabolous insect Tribolium castaneum. Depletion of E93 prevents pupa formation, whereas precocious E93 upregulation, by either JH depletion or nutrition restriction, induces premature onset of metamorphosis.Body size in holometabolous insects is determined by the size at which the juvenile larva undergoes metamorphosis to the pupal stage. To undergo larva-pupa transition, larva must reach a critical developmental checkpoint, the threshold size (TS); however, the molecular mechanisms through which the TS cues this transition remain to be fully characterized. Here, we use the flour beetle Tribolium castaneum to characterize the molecular mechanisms underlying entry into metamorphosis. We found that T. castaneum reaches a TS at the beginning of the last larval instar, which is associated with the downregulation of TcKr-h1 and the upregulation of TcE93 and TcBr-C. Unexpectedly, we found that while there is an association between TS and TcE93 upregulation, it is the latter that constitutes the molecular trigger for metamorphosis initiation. In light of our results, we evaluate the interactions that control the larva-pupa transition and suggest alternative models.
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | artículo biblioteca |
| Published: |
Elsevier
2019-04-23
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| Subjects: | Insect metamorphosis, Growth control, Threshold size, Juvenile hormone, Ecdysone, E93, Kr-h1, Broad complex, Holometaboly, Tribolium castaneum, |
| Online Access: | http://hdl.handle.net/10261/206144 http://dx.doi.org/10.13039/501100000780 http://dx.doi.org/10.13039/501100003329 http://dx.doi.org/10.13039/501100002809 |
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