Reference Report

Reference
Citation	Mirth, C., Truman, J.W., Riddiford, L.M. (2005). The role of the prothoracic gland in determining critical weight for metamorphosis in Drosophila melanogaster. Curr. Biol. 15(20): 1796--1807. (Export to RIS)
FlyBase ID	FBrf0190035
Publication Type	Research paper
PubMed ID	16182527
PubMed Abstract	The timely onset of metamorphosis in holometabolous insects depends on their reaching the appropriate size known as critical weight. Once critical weight is reached, juvenile hormone (JH) titers decline, resulting in the release of prothoracicotropic hormone (PTTH) at the next photoperiod gate and thereby inducing metamorphosis. How individuals determine when they have reached critical weight is unknown. We present evidence that in Drosophila, a component of the ring gland, the prothoracic gland (PG), assesses growth to determine when critical weight has been achieved.We used the GAL4/UAS system to suppress or enhance growth by overexpressing PTEN or Dp110, respectively, in various components of the ring gland. Suppression of the growth of the PG and CA, but not of the CA alone, produced larger-than-normal larvae and adults. Suppression of only PG growth resulted in nonviable larvae, but larvae with enlarged PGs produced significantly smaller larvae and adults. Rearing larvae with enlarged PGs under constant light enhanced these effects, suggesting a role for photoperiod-gated PTTH secretion. These larvae are smaller, in part as a result of their repressed growth rates, a phenotype that could be rescued through nutritional supplementation (yeast paste). Most importantly, larvae with enlarged PGs overestimated size so that they initiated metamorphosis before surpassing the minimal viable weight necessary to survive pupation.The PG acts as a size-assessing tissue by using insulin-dependent PG cell growth to determine when critical weight has been reached.
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Language of Publication	English
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Publication Type	Journal
Abbreviation	Curr. Biol.
Title	Current Biology
Publication Year	1991-
ISBN/ISSN	0960-9822
Data from Reference
Alleles (7)
	InR^Scer\UAS.cHa Mmus\Cd8a^{Scer\UAS.T:Avic\GFP} Pi3K92E^{Scer\UAS.T:Hsap\MYC} Pten^Scer\UAS.cGb Scer\GAL4^Aug21 Scer\GAL4^P0206 Scer\GAL4^phm.PO
Constructs (5)
	P{phm-GAL4.O} P{UAS-InR.H} P{UAS-mCD8::GFP.L} P{UAS-Pten.Gb} P{WT-Dp110}
Genes (7)
	InR Mmus\Cd8a Pi3K92E Pten Scer\GAL4 T:Avic\GFP T:Hsap\MYC
Insertions (2)
	P{GAL4}P0206 P{GawB}Aug21