Persistent Link:
http://hdl.handle.net/10150/195273
Title:
Lipid Metabolic Pathways in the Midgut of Manduca sexta
Author:
Zamora, Jorge
Issue Date:
2006
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Insects such as Manduca sexta must be efficient in obtaining energy stores in order to survive. The main goal of the M. sexta larva is to eat and store enough energy to reach the adult stage, produce eggs (in the case of females), and reproduce. Triacylglycerol (TAG), the most important energy storage molecule, is stored mainly in adipose tissues in lipid droplets, although other tissues are also able to store TAG in similar organelle structures but to a lesser degree. The phosphatidic acid (PA) pathway and the 2-monoacylglycerol (MAG) pathway are both energy-dependant acyl-CoA processes and are the main synthetic pathways by which TAG is synthesized in adipose and other tissues. My research led to the discovery of an energy-independent pathway for the synthesis of TAG that was present in the M. sexta midgut. Based on partial purification, a transacylase/lipase enzyme is present and responsible for DAG and TAG synthesis in the M.sexta midgut. Lipogenesis and lipolysis in adipose tissue involves a series of enzymes. Adiponutrin and desnutrin, two proteins involved in fat homeostasis in humans and mice, have received a lot of attention since their activities are dependent on the fed or unfed state of the animal. In this study, bioinformatics analyses were performed, which allowed the identification of an insect gene that has an ortholog in human and mice that plays an important role in adipose tissue TAG hydrolysis and synthesis. Only one insect gene ortholog was found to be present in the Aedes aegypti (mosquito), Drosophila melanogaster (fruit fly), Anopheles gambiae (mosquito), Bombyx mori (silk worm), and Tribolium castaneum (red flour beetle) genomes corresponding to genes involved in the regulation of TAG metabolism in mice (adiponutrin, desnutrin) and humans (iPLA-epsilon, iPLA-zeta, and iPLA-eta). Expression of the M. sexta calcium-independent phospholipase A2 (iPLA) ortholog has demonstrated that the protein is able to transfer acyl groups between MAGs in an energy-independent manner, similar to that in human iPLAs. This is the first example of a transacylase identified in insects.
Type:
text; Electronic Dissertation
Keywords:
Biochemistry
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Biochemistry; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Miesfeld, Roger L.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleLipid Metabolic Pathways in the Midgut of Manduca sextaen_US
dc.creatorZamora, Jorgeen_US
dc.contributor.authorZamora, Jorgeen_US
dc.date.issued2006en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractInsects such as Manduca sexta must be efficient in obtaining energy stores in order to survive. The main goal of the M. sexta larva is to eat and store enough energy to reach the adult stage, produce eggs (in the case of females), and reproduce. Triacylglycerol (TAG), the most important energy storage molecule, is stored mainly in adipose tissues in lipid droplets, although other tissues are also able to store TAG in similar organelle structures but to a lesser degree. The phosphatidic acid (PA) pathway and the 2-monoacylglycerol (MAG) pathway are both energy-dependant acyl-CoA processes and are the main synthetic pathways by which TAG is synthesized in adipose and other tissues. My research led to the discovery of an energy-independent pathway for the synthesis of TAG that was present in the M. sexta midgut. Based on partial purification, a transacylase/lipase enzyme is present and responsible for DAG and TAG synthesis in the M.sexta midgut. Lipogenesis and lipolysis in adipose tissue involves a series of enzymes. Adiponutrin and desnutrin, two proteins involved in fat homeostasis in humans and mice, have received a lot of attention since their activities are dependent on the fed or unfed state of the animal. In this study, bioinformatics analyses were performed, which allowed the identification of an insect gene that has an ortholog in human and mice that plays an important role in adipose tissue TAG hydrolysis and synthesis. Only one insect gene ortholog was found to be present in the Aedes aegypti (mosquito), Drosophila melanogaster (fruit fly), Anopheles gambiae (mosquito), Bombyx mori (silk worm), and Tribolium castaneum (red flour beetle) genomes corresponding to genes involved in the regulation of TAG metabolism in mice (adiponutrin, desnutrin) and humans (iPLA-epsilon, iPLA-zeta, and iPLA-eta). Expression of the M. sexta calcium-independent phospholipase A2 (iPLA) ortholog has demonstrated that the protein is able to transfer acyl groups between MAGs in an energy-independent manner, similar to that in human iPLAs. This is the first example of a transacylase identified in insects.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectBiochemistryen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineBiochemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairMiesfeld, Roger L.en_US
dc.contributor.committeememberBaldwin, T.en_US
dc.contributor.committeememberMcEvoy, M.en_US
dc.contributor.committeememberNagy, L.en_US
dc.contributor.committeememberTollin, G.en_US
dc.contributor.committeememberTsao, T.en_US
dc.identifier.proquest1893en_US
dc.identifier.oclc659746453en_US
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