Milton controls the early acquisition of mitochondria by Drosophila oocytes.
Mitochondria in many species enter the young oocyte en mass from interconnected germ cells to generate the large aggregate known as the Balbiani body. Organelles and germ plasm components frequently associate with this structure. Balbiani body mitochondria are thought to populate the germ line, ensuring that their genomes will be inherited preferentially. We find that milton, a gene whose product was previously shown to associate with Kinesin and to mediate axonal transport of mitochondria, is needed to form a normal Balbiani body. In addition, germ cells mutant for some milton or Kinesin heavy chain (Khc) alleles transport mitochondria to the oocyte prematurely and excessively, without disturbing Balbiani body-associated components. Our observations show that the oocyte acquires the majority of its mitochondria by competitive bidirectional transport along microtubules mediated by the Milton adaptor. These experiments provide a molecular explanation for Balbiani body formation and, surprisingly, show that viable fertile offspring can be obtained from eggs in which the normal program of mitochondrial acquisition has been severely perturbed.
Cox
Rachel T
RT
Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution of Washington, 3520 San Martin Drive, Baltimore, MD 21218, USA.
Spradling
Allan C
AC
D000818:Animals; D015153:Blotting, Western; D019521:Body Patterning; D002455:Cell Division / Q000502:physiology; D019976:Cloning, Organism; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster / Q000502:physiology*; D004398:Dyneins / Q000502:physiology; D016547:Kinesins / Q000502:physiology; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009865:Oocytes / Q000502:physiology*; D009866:Oogenesis / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; C470348:milt protein, Drosophila; D004398:Dyneins; D016547:Kinesins