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First published online November 11, 2004
doi: 10.1242/10.1242/dev.01459

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Epsin potentiates Notch pathway activity in Drosophila and C. elegans

¹ Department of Genetics, Washington University in St Louis, School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA
² Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada

View larger version (56K): [in a new window]   Fig. 1. lqf and Notch display similar heart phenotypes. Dorsal views of stage 16 wild-type (A-C), lqfARI (D-F) and Nts-1/Df(1)81k (G-I) embryos labeled with dMEF2 for cardioblasts (red) and Zfh-1 for pericardial cells (green). (A-C) In wild-type, cardioblasts align in two cell rows to form the heart (A,C); the pericardial cells flank the cardioblasts (B,C). (D-I) In lqfARI and Nts-1/Df(1)81k mutant embryos, excess cardioblasts form three to four poorly organized cell rows in the heart (D,F,G,I). In both lqf and Notch embryos relatively normal numbers of pericardial cells develop (E,F,H,I). Anterior – left.

View larger version (125K): [in a new window]   Fig. 2. lqf promotes dorsal muscle development. Dorsal views of stage 15 wild-type (A,B) and lqfAG embryos (C,D) stained for myosin heavy chain (MHC; A,C) to label the heart and somatic muscles and Eve (B,D) to label nuclei within the DA1 muscle and Eve-pericardial cells (EPC). (A) MHC expression outlines the muscle pattern in the dorsal mesoderm. (C) In lqfAG embryos, the muscle pattern appears grossly normal but the size of dorsal muscles appears reduced. To aid visualization of muscles, lines demarcate the size and orientation of the DA1 and DO2 dorsal muscles and arrowheads identify the heart (A,C). (B) In wild-type embryos, each DA1 muscle (dashed circles) contains roughly 11 Eve-positive nuclei while DA1 muscles in lqf embryos (D; dashed circles) contain on average eight Eve-positive nuclei. Arrowheads in B and D identify EPC. Anterior – left.

View larger version (77K): [in a new window]   Fig. 3. lqf collaborates with the Notch pathway to regulate cardioblast development. Dorsal views of stage 16 wild-type (A), lqfARI (B), Nts-1 (C), lqfARIDl3/lqfARI+ (D), Nts-1;lqfARI/+ (E) and lqfARI neur1/lqfARI+ (F) embryos labeled for cardioblasts. (A) Wild-type cardioblast pattern. (B,C) Nts-1 embryos grown at 30°C (C), and lqfARI embryos grown at 18°C (B), exhibit near wild-type cardioblast patterns with very mild increases in cardioblast number. (D) Nts-1;lqfARI/+ embryos grown at 30°C exhibit a clear increase in cardioblast number as do lqf Dl3/lqfARI+ (E) and lqfARI neur1/lqfARI+ (F) embryos grown at 18°C. Anterior – left.

View larger version (99K): [in a new window]   Fig. 4. lqf genetically interacts with Delta during wing vein formation. Dorsal views of wild-type (A,B), Dl3/+ (C,D) and Dl3+/+lqfARI (E,F) wings. (A,B) Wild-type patterns of the L2 vein (A) as well as of the L5 vein and posterior cross vein (PCV) (B). (C) Dl3/+ wings exhibit vein thickening at the tip (arrowhead) and along the length (arrow) of L2. (D) Dl3/+ wings also exhibit thickening of L5 (arrow) and vein bifurcation at the junction of the posterior cross vein and L5 (arrowhead). (E,F) Dl3+/+lqfARI wings exhibit severe vein thickening at the tip and along the length of L2 (E; arrow, arrowhead) as well along L5 (F, arrow). The bifurcation of the L5 and posterior cross vein is also more severe in Dl3+/+lqfARI wings (F, arrowhead). The percentage of flies of indicated genotype that exhibit noted phenotypes is given in the bottom right of each panel. Proximal – right.

View larger version (46K): [in a new window]   Fig. 5. Notch and lqf genetically interact to inhibit bristle development. Dorsal views of wild-type (A) and N55e11/+; lqfARI/+ (B) nota and a graphical representation of bristle phenotypes in N55e11/+, lqfARI/+ and N55e11/+; lqfARI/+ nota. (A) Wild-type notal and scutellar bristle pattern. (B) Ectopic bristles develop on the notum and scutellum of N55e11/+; lqfARI/+ flies (arrows). (C) Quantification of the percentage of flies that exhibit ectopic notal and scutellar bristles for the genotypes – lqfARI/+, N55e11/+, and N55e11/+;lqfARI/+.

View larger version (41K): [in a new window]   Fig. 6. Ce-epn-1(RNAi) enhances the premature meiotic entry defect of glp-1(bn18) mutants. (A) Dissected gonad arms stained with DAPI to visualize DNA morphology. Distal is left and the proximal portions of the gonad arms are not shown. Brackets mark the regions of gonad arms containing proliferative nuclei. Wild-type (top), Ce-epn-1 (RNAi) (second from top) and glp-1(bn18) (third from top) animals all contain a proliferative zone one day past the fourth larval stage, however the proliferative zones are smaller in the epn-1(RNAi) and glp-1(bn18) animals. glp-1(bn18); epn-1(RNAi) animals (bottom) of the same age lack a proliferative zone, but rather have sperm extending to the distal end. All animals were grown at 20°C. Scale bar: 20 µm. (B) Quantification of percentages of worms that exhibit strong glp-1 phenotype, lack of proliferative zone phenotype. aGonad arms were determined to be Glp if they had sperm or oocytes at the very distal end of the gonad or if no proliferative cells were present as evidenced by HIM-3(plus)/REC-8(minus) cells at the very distal end of the gonad. bN refers to the number of gonad arms examined. cThis percentage of Glp is somewhat higher than what has previously been described for glp-1(bn18) at 20°C, however this is probably due to the plates being slightly above 20°C prior to placing the eggs on them. (C) Quantification of proliferative zone size in worms that contain reduced proliferative zone based on HIM-3 and REC-8 staining. Error bars represent s.d.