RT Journal Article
SR Electronic
T1 TGF-beta/Activin ligand Myoglianin couples muscle growth to the initiation of metamorphosis
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.04.21.053835
DO 10.1101/2020.04.21.053835
A1 Lorrie L. He
A1 Sara Hyun Joo Shin
A1 Zhou Wang
A1 Isabelle Yuan
A1 Ruthie Weschler
A1 Allie Chiou
A1 Takashi Koyama
A1 H. Frederik Nijhout
A1 Yuichiro Suzuki
YR 2020
UL http://biorxiv.org/content/early/2020/04/23/2020.04.21.053835.abstract
AB Although the mechanisms that control growth are now well understood, the mechanism by which animals assess their body size remains one of the great puzzles in biology. The final larval instar of holometabolous insects, after which growth stops and metamorphosis begins, is specified by a threshold size. We investigated the mechanism of threshold size assessment in the tobacco hornworm, Manduca sexta. The threshold size was found to change depending on the amount of exposure to poor nutrient conditions whereas hypoxia treatment consistently led to a lower threshold size. Under these various conditions, the mass of the muscles plus integuments was correlated with the threshold size. Furthermore, the expression of myoglianin (myo) increased at the threshold size in both M. sexta and Tribolium castaneum. Knockdown of myo in T. castaneum led to larvae that underwent supernumerary larval molts and stayed in the larval stage permanently even after passing the threshold size. We propose that increasing levels of Myo produced by the growing tissues allow larvae to assess their body size and trigger metamorphosis at the threshold size.Competing Interest StatementThe authors have declared no competing interest.