title: Knockdown of Drosophila hemoglobin suggests a role in O2 homeostasis.
abstract: Almost all insects are equipped with a tracheal system, which appears to be sufficient for O2 supply even in phases of high metabolic activity. Therefore, with the exception of a few species dwelling in hypoxic habitats, specialized respiratory proteins had been considered unnecessary in insects. The recent discovery and apparently universal presence of intracellular hemoglobins in insects has remained functionally unexplained. The fruitfly Drosophila melanogaster harbors three different globin genes (referred to as glob1-3). Glob1 is the most highly expressed globin and essentially occurs in the tracheal system and the fat body. To better understand the functions of insect globins, the levels of glob1 were modulated in Drosophila larvae and adults by RNAi-mediated knockdown and transgenic over-expression. No effects on the development were observed in flies with manipulated glob1 levels. However, the knockdown of glob1 led to a significantly reduced survival rate of adult flies under hypoxia (5% and 1.5% O2). Surprisingly, the glob1 knockdown flies also displayed increased resistance towards the reactive oxygen species-forming agent paraquat, which may be explained by a restricted availability of O2 resulting in decreased formation of harmful O2(-). In summary, our results suggest an important functional role of glob1 in O2 homeostasis, possibly by enhancing O2 supply.
authors.affiliation: Institute of Molecular Genetics, University of Mainz, D-55099 Mainz, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Gleixner
authors.affiliation: Institute of Molecular Genetics, University of Mainz, D-55099 Mainz, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Ripp
authors.affiliation: Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, CH-8057 Zurich, Switzerland; Regenerative Medicine Program, University and University Hospital Zurich, CH-8901 Zurich, Switzerland.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Gorr
authors.affiliation: Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schuh
authors.affiliation: Institute of Molecular Genetics, University of Mainz, D-55099 Mainz, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wolf
authors.affiliation: Institute of Zoology and Zoological Museum, Biocenter Grindel, University of Hamburg, D-20146 Hamburg, Germany. Electronic address: thorsten.burmester@uni-hamburg.de.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Burmester
authors.affiliation: Institute of Molecular Genetics, University of Mainz, D-55099 Mainz, Germany. Electronic address: hankeln@uni-mainz.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hankeln
mesh_terms: D000818:Animals; D029721:Drosophila Proteins / Q000096:biosynthesis* / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D005914:Globins / Q000096:biosynthesis* / Q000235:genetics; D006454:Hemoglobins / Q000096:biosynthesis / Q000235:genetics; D006706:Homeostasis; D007814:Larva; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000378:metabolism*; D010269:Paraquat / Q000494:pharmacology; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D006454:Hemoglobins; D017382:Reactive Oxygen Species; D005914:Globins; D010269:Paraquat; D010100:Oxygen
keywords: Hemoglobin; Hypoxia; Oxygen; Reactive oxygen species; Respiration; Tracheae