Fig. 1.

Animals lacking dLipin are characterized by pharate adult lethality and underdevelopment of the larval fat body. (A) Genomic structure of the dLipin gene. The inverted triangle indicates the insertion site of the piggyBac transposon in the dLipin^e00680 allele. Black boxes represent exons. The deficiencies Df(2R)Exel7095 and Df(2R)NCX10 remove chromosomal regions 43E7 to 44C5 and 44B3 to 44C2, respectively, including the entire dLipin gene at 44B4 to 44B5. dLipin encodes two protein isoforms with different C termini that result from alternative splicing, as indicated. (B) Animals homozygous for dLipin^e00680, or transheterozygous for dLipin^e00680 and Df(2R)Exel7095 (dLipin/Df), contain reduced levels of dLipin mRNA and protein. RNA for Northern blot analysis was from whole prepupae and pupae, and protein for Western blot analysis was from wandering third-instar larvae. Control samples were obtained from w¹¹¹⁸ animals. Detection of rp49 mRNA and actin protein served as a control for loading and transfer. (C) Animals homozygous for dLipin^e00680 develop into pharate adult flies that do not show obvious developmental defects (animal in middle, dissected from pupal case). However, many of these flies die and become necrotic while still enclosed in the pupal case (animal on the right). Note that mutant and control pupae are similar in size, indicating that a lack of dLipin does not lead to an overall growth defect. (D) A lack of dLipin causes severe underdevelopment of the larval fat body. (Top) dLipin mutant larvae appear translucent due to a lack of fat tissue. (Center) Inclusion of the Dcg-GFP fat body marker (33) in the mutant background confirms that the amount of fat tissue is dramatically reduced. (Bottom) The same phenotype is obtained when dLipin expression is knocked down by RNAi using the ubiquitous tubulin driver. Bars, 1 mm.