Fig. 8. GOBP2 expression in larval antenna through a fourth-fifth instar molt cycle. (A,B) The relationship between the developmental stage, levels of ecdysteroid and juvenile hormone (JH) and gene expression are indicated from fourth instar to adult, modified from Riddiford (1995). Lettered asterisks (a-k) in (A) indicate developmental stages represented by tissues shown in (C). Significant developmental events are indicated in all-capitalized text above graph. Ecdysteroid titers are from Bollenbacher et al. (1981) and Warren and Gilbert (1986); JH titers are from Fain and Riddiford (1975) and Baker et al. (1987). Expression profiles of four ecdysteroid sensitive genes are shown in black, reviewed in Riddiford (1995): INS, insecticyanin; LCP 14, larval cuticle protein; LCP 16.6, larval endocuticle protein; DDC dopa decarboxylase. Temporal expression of GOBP2Msex in larva is indicated in (A), from this study; expression of GOBP2Msex and PBP1Msex in pupa is indicated in (B), from Vogt et al. (1993). (C) Whole-mount in situ hybridizations of developmentally staged tissue, each representative of five individuals. Arrows indicate positively stained cell clusters; asterisks indicate staining entering the third antennal segment. (a-k) Tissue correlated with the time points indicated by lettered asterisks in A. 4^th, feeding fourth instar larva day 1; SA, spiracle apolysis; SH, slipped head, with hours after indicated (e.g. SH+3=SH+3 h). Ecd 5^th, animal within 2 h of molting; Day-1 5^th is 24 h after molting. ‘Wandering’ is an animal on the first day of wandering (W1, in A), a non-feeding pre-pupal stage that initiates about 5 days after molting. The time between SA 15-16 and SH was approximately 8 h, and between SH+30 and Ecd 5^th, approximately 5 h. Apolysis, or the detachment of the epidermis from the cuticle, occurred following stage SA15-16, and is indicated by the loss of antennal form observed at SH (d). The formation of new fifth instar larval cuticle is indicated by the structural form the antenna has reacquired by stage SH+22 (f). The fourth instar larval cuticle is not shed until ecdysis (Ecd 5^th, h), after which the cuticle becomes tanned, as indicated by the brown coloration in the Day-1 5^th and ‘Wandering’ tissues (i,k). Size bar, 150 µm.

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