Genetic Interaction of Lobe With Its Modifiers in Dorsoventral Patterning and Growth of the Drosophila Eye

Abstract

Dorsoventral (DV) patterning is essential for growth of the Drosophila eye. Recent studies suggest that ventral is the default state of the early eye, which depends on Lobe (L) function, and that the dorsal fate is established later by the expression of the dorsal selector gene pannier (pnr). However, the mechanisms of regulatory interactions between L and dorsal genes are not well understood. For studying the mechanisms of DV patterning in the early eye disc, we performed a dominant modifier screen to identify additional genes that interact with L. The criterion of the dominant interaction was either enhancement or suppression of the L ventral eye loss phenotype. We identified 48 modifiers that correspond to 16 genes, which include fringe ( fng), a gene involved in ventral eye patterning, and members of both Hedgehog (Hh) and Decapentaplegic (Dpp) signaling pathways, which promote L function in the ventral eye. Interestingly, 29% of the modifiers (6 enhancers and 9 suppressors) identified either are known to interact genetically with pnr or are members of the Wingless (Wg) pathway, which acts downstream from pnr. The detailed analysis of genetic interactions revealed that pnr and L mutually antagonize each other during second instar of larval development to restrict their functional domains in the eye. This time window coincides with the emergence of pnr expression in the eye. Our results suggest that L function is regulated by multiple signaling pathways and that the mutual antagonism between L and dorsal genes is crucial for balanced eye growth.

LobeandSerrateare required for cell survival during early eye development inDrosophila

“…We have used Drosophila eye to identify the genes required for cell survival and to sustain early growth. Previously, we have shown that ventral is the ground state of the entire early larval eye primordium (Singh and Choi, 2003), and that L/Ser are required for development of the ventral eye (Chern and Choi, 2002;Singh and Choi, 2003;Singh et al, 2005a;Singh et al, 2005b). During early eye development, little or no cell death is observed.…”

“…L 2 , a dominant-negative allele of L, shows loss of ventral eye in the L 2 /+ background in 100% of flies (Fig. 4A,B) (Singh and Choi, 2003;Singh et al, 2005a). We overexpressed cyclin A, cyclin B and cyclin E to accelerate cell-cycle progression in the L 2 /+-mutant background and did not find any significant rescues (data not shown).…”

“…In a genetic screen, we identified Shaggy (Sgg), an antagonist of Wg Signaling (Hazelett et al, 1998;Heslip et al, 1997), as the modifier of the L-mutant phenotype (Singh et al, 2005a). To test if the loss of L results in the abnormal induction of Wg signal and thereby causes cell death, we overexpressed the members of the Wg-signaling pathway to increase or decrease the levels of Wg signaling and sampled its effect on the L-mutant phenotype.…”

Perspectives of Biosynthesized Magnesium Nanoparticles in Foliar Application of Wheat Plant

“…Total chlorophyll content was estimated by the method of Lichtenhaler, 15 total protein released was analysed by Lowry et al, 16 elemental analysis P, Mg, Fe, Cu was done as described by Jackson. 17 Plant P was estimated as described by Singh et al 18 The Fungi was isolated following the standard procedure. 19 Nitrate reductase activities was estimated following Jawarski, 20 while Aryl sulfatase and Esterase was estimated by Tabatabai and Bremner 21 and Schnurer and Rossawall, 22 respectively.…”

Reduction of Lobe leads to TORC1 hypoactivation that induces ectopic Jak/STAT signaling to impair Drosophila eye development

“…L mutants have reduced adult eyes and exhibit ectopic apoptosis during eye development, indicating that L is required for eye development (Chern and Choi, 2002;Singh et al, 2005;Singh et al, 2006). But whether it regulates eye development via regulation of TORC1 activity is unknown.…”