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Milton assembles large mitochondrial clusters, mitoballs, to sustain spermatogenesis.

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Li, Andy YZ 
Di, Ying 
Rathore, Sumaera 
Chiang, Ason C-Y 
Jezek, Jan 


Mitochondria are dynamic organelles that undergo frequent remodeling to accommodate developmental needs. Here, we describe a striking organization of mitochondria into a large ball-like structure adjacent to the nucleus in premeiotic Drosophila melanogaster spermatocytes, which we term "mitoball". Mitoballs are transient structures that colocalize with the endoplasmic reticulum, Golgi bodies, and the fusome. We observed similar premeiotic mitochondrial clusters in a wide range of insect species, including mosquitos and cockroaches. Through a genetic screen, we identified that Milton, an adaptor protein that links mitochondria to microtubule-based motors, mediates mitoball formation. Flies lacking a 54 amino acid region in the C terminus of Milton completely lacked mitoballs, had swollen mitochondria in their spermatocytes, and showed reduced male fertility. We suggest that the premeiotic mitochondrial clustering is a conserved feature of insect spermatogenesis that supports sperm development.



Milton-mediated mitochondrial trafficking, insect spermatogenesis, male fertility, mitoballs, mitochondrial clustering, Animals, Male, Drosophila melanogaster, Drosophila Proteins, Mitochondria, Semen, Spermatogenesis, Nerve Tissue Proteins

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Proc Natl Acad Sci U S A

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Proceedings of the National Academy of Sciences
European Research Council (803852)
Wellcome Trust (202269/Z/16/Z)
Cancer Research UK (C6946/A24843)
Wellcome Trust (203144/A/16/Z)
European Research Council Starting Grant