Handling Editor: Cassandra Extavour
ABSTRACT
Insect metamorphosis originated around the middle Devonian, associated with the innovation of the final molt; this occurs after histolysis of the prothoracic gland (PG; which produces the molting hormone) in the first days of adulthood. We previously hypothesized that transcription factor E93 is crucial in the emergence of metamorphosis, because it triggers metamorphosis in extant insects. This work on the cockroach Blattella germanica reveals that E93 also plays a crucial role in the histolysis of PG, which fits the above hypothesis. Previous studies have shown that the transcription factor FTZ-F1 is essential for PG histolysis. We have found that FTZ-F1 depletion towards the end of the final nymphal instar downregulates the expression of E93, whereas E93-depleted nymphs molt to adults that retain a functional PG. Interestingly, these adults are able to molt again, which is exceptional in insects. The study of insects able to molt again in the adult stage may reveal clues about how nymphal epidermal cells definitively become adult cells, and whether it is possible to reverse this process.
Footnotes
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: O.K., X.B.; Methodology: O.K., X.B.; Formal analysis: O.K., X.B.; Investigation: O.K., X.B.; Resources: X.B.; Writing - original draft: O.K., X.B.; Writing - review & editing: X.B.; Supervision: X.B.; Project administration: X.B.; Funding acquisition: X.B.
Funding
O.K. received a Royal Thai Government Scholarship to carry out a PhD thesis in X.B.’s laboratory in Barcelona. This work was supported by the Ministerio de Economia y Competitividad (CGL2012–36251, CGL2015–64727-P and PID2019-104483GB-I00 to X.B.), the Consejo Superior de Investigaciones Científicas (2019AEP029), the Generalitat de Catalunya (2017 SGR 1030 to X.B.) and the European Regional Development Fund.
Supplementary information
Supplementary information available online at https://dev.biologists.org/lookup/doi/10.1242/dev.190066.supplemental
- Received March 1, 2020.
- Accepted October 13, 2020.
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