Fat-body brummer lipase determines survival and cardiac function during starvation in Drosophila melanogaster

Vitellogenic ovaries from Drosophila melanogaster flies have been exposed, either in in vivo or in vitro conditions, to various extracellular tracers in an attempt to determine the possible route of entry of the yolk precursors. Ruthenium red and lanthanum nitrate have been shown to gain access to the oocyte surface by initially passing through the intercellular spaces of the follicle layer. Both these tracers, however, never attain an intracellular location within any of the cells forming the ovarian chamber. Colloidal Thorotrast when injected into adult females has never been detected within any of the ovarian chambers examined, irrespective of their stage. Vitellogenic oocytes exposed to peroxidase in in vivo conditions exhibit the oolemma and all the structural elements present in the cortical ooplasm well labelled within a very short time after the injection. Moreover, with gradually increasing exposure times to peroxidase, the labelled yolk platelets increase progressively in number. At each time interval after the injection, the label over the yolk platelets remains restricted to the superficial layer and never gets into the associated body. The pattern of tritiated lysine incorporation into vitellogenic oocytes has been studied over a period of 20 h. A few hours after injection of the radioactive tracer, the silver grains located over the ooplasm appear distributed at random. A predominant labelling of the yolk platelets as compared to the rest of the ooplasm, becomes evident only with a 6 h delay since the time of injection. When analysed by electrophoresis and isolectrofocusing, the vitellogenic ovary is seen to exhibit a number of protein bands which are common to those of other tissues as, for instance, haemolymph and fat body. The evidence obtained in the present study is discussed in relation to the hypothesis of an extraovarian origin of the yolk precursors and their sequestration into forming yolk platelets.

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Systemic and heart autonomous effects of sphingosine Δ4 desaturase deficiency in lipotoxic cardiac pathophysiology

Disease Models & Mechanisms ◽

10.1242/dmm.043083 ◽

2020 ◽

Vol 13 (8) ◽

pp. dmm043083

Author(s):

Stanley M. Walls ◽

Dale A. Chatfield ◽

Karen Ocorr ◽

Greg L. Harris ◽

Rolf Bodmer

Keyword(s):

Cardiac Function ◽

Fat Body ◽

Model Systems ◽

Specific Expression ◽

Cardiac Pathology ◽

Cardiac Chamber ◽

Spatial Regulation ◽

Cardiac Pathophysiology ◽

Cardiac Steatosis ◽

Fractional Shortening

ABSTRACTLipotoxic cardiomyopathy (LCM) is characterized by cardiac steatosis, including the accumulation of fatty acids, triglycerides and ceramides. Model systems have shown the inhibition of ceramide biosynthesis to antagonize obesity and improve insulin sensitivity. Sphingosine Δ4 desaturase (encoded by ifc in Drosophila melanogaster) enzymatically converts dihydroceramide into ceramide. Here, we examine ifc mutants to study the effects of desaturase deficiency on cardiac function in Drosophila. Interestingly, ifc mutants exhibited classic hallmarks of LCM: cardiac chamber dilation, contractile defects and loss of fractional shortening. This outcome was phenocopied in global ifc RNAi-mediated knockdown flies. Surprisingly, cardiac-specific ifc knockdown flies exhibited cardiac chamber restriction with no contractile defects, suggesting heart autonomous and systemic roles for ifc activity in cardiac function. Next, we demonstrated that ifc mutants exhibit suppressed Sphingosine kinase 1 (Sk1) expression. Ectopic overexpression of Sk1 was sufficient to prevent cardiac chamber dilation and loss of fractional shortening in ifc mutants. Partial rescue was also observed with cardiac- and fat-body-specific Sk1 overexpression. Finally, we showed that cardiac-specific expression of Drosophila inhibitor of apoptosis (dIAP) also prevented cardiac dysfunction in ifc mutants, suggesting a role for caspase activity in the observed cardiac pathology. Collectively, we show that spatial regulation of sphingosine Δ4 desaturase activity differentially affects cardiac function in heart autonomous and systemic mechanisms through tissue interplay.

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The role of the ovary and nutritional signals in the regulation of fat body yolk protein gene expression in Drosophila melanogaster

Journal of Insect Physiology ◽

10.1016/0022-1910(90)90097-y ◽

1990 ◽

Vol 36 (7) ◽

pp. 471-479 ◽

Cited By ~ 23

Author(s):

Mary Bownes ◽

Gregor Reid

Keyword(s):

Gene Expression ◽

Drosophila Melanogaster ◽

Protein Gene ◽

Fat Body ◽

Yolk Protein

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Cell lineage analysis of kynurenine producing organs inDrosophila melanogaster

Genetics Research ◽

10.1017/s0016672300015858 ◽

1975 ◽

Vol 26 (1) ◽

pp. 63-72 ◽

Cited By ~ 15

Author(s):

Moti Nissani

Keyword(s):

Drosophila Melanogaster ◽

Fat Body ◽

Cell Lineage ◽

Chromosome Loss ◽

Wild Type ◽

Fate Map ◽

Lineage Analysis

SUMMARYSix hundred and ten gynandromorphs were produced in which anXchromosome loss uncovered the vermilion mutation. The mosaic patterns observed indicate that wild type ocelli are incapable of kynurenine production and that, in addition to the eyes, postembryonic kynurenine producing cells originate from two separate regions of the blastoderm. The positions of these regions on the genetic fate map ofDrosophila melanogastercorrespond to the embryonic precursors which give rise to the kynurenine producing cells of the larval fat body and Malpighian tubes.

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Effect of sexual maturation on DD2R gene expression in fat body of Drosophila melanogaster females

Russian Journal of Genetics ◽

10.1134/s1022795413090056 ◽

2013 ◽

Vol 49 (9) ◽

pp. 979-981

Author(s):

O. V. Laukhina ◽

E. A. Filipenko ◽

I. Yu. Rauschenbach

Keyword(s):

Gene Expression ◽

Drosophila Melanogaster ◽

Sexual Maturation ◽

Fat Body

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The ecdysone response enhancer of the Fbp1 gene of Drosophila melanogaster is a direct target for the EcR/USP nuclear receptor.

Molecular and Cellular Biology ◽

10.1128/mcb.14.7.4465 ◽

1994 ◽

Vol 14 (7) ◽

pp. 4465-4474 ◽

Cited By ~ 47

Author(s):

C Antoniewski ◽

M Laval ◽

A Dahan ◽

J A Lepesant

Keyword(s):

Drosophila Melanogaster ◽

Binding Site ◽

Fat Body ◽

Sequence Similarity ◽

High Concentration ◽

Direct Role ◽

Palindromic Structure ◽

Fbp1 Gene

The transcription of the Drosophila melanogaster Fbp1 gene is induced by the steroid hormone 20-hydroxyecdysone and restricted to the late-third-instar fat body tissue. In a previous study we showed that the -68 to -138 region relative to the transcription start site acts as an ecdysone-dependent third-instar fat body-specific enhancer in a transgenic assay. Here we report that seven nucleoprotein complexes are formed in vitro on this enhancer when a nuclear extract from late-third-instar fat body is used in a gel shift assay. Accurate mapping of the binding sites of the complexes revealed a remarkably symmetrical organization. Using specific antibodies, one of the complexes was identified as a heterodimer consisting of the ecdysone receptor (EcR) and Ultraspiracle (USP) proteins. The binding site of the heterodimer as defined by mutagenesis and methylation interference experiments bears strong sequence similarity to the canonical hsp27 ecdysone response element, including an imperfect palindromic structure. The two elements diverge at three positions in both half-sites, indicating that the structure of an active EcR/USP binding site allows considerable sequence variations. In vivo footprinting experiments using ligation-mediated PCR and wild-type or ecdysteroid-deficient larvae show that occupancy of the Fbp1 EcR/USP binding site and adjacent region is dependent on a high concentration of ecdysteroids. These results provide strong evidence for a direct role of the EcR/USP heterodimer in driving gene expression in response to changes of the ecdysteroid titer during Drosophila larval development.

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