Intraflagellar transport is required in Drosophila to differentiate sensory cilia but not sperm.
BACKGROUND
Intraflagellar transport (IFT) uses kinesin II to carry a multiprotein particle to the tips of eukaryotic cilia and flagella and a nonaxonemal dynein to return it to the cell body. IFT particle proteins and motors are conserved in ciliated eukaryotes, and IFT-deficient mutants in algae, nematodes, and mammals fail to extend or maintain cilia and flagella, including sensory cilia. In Drosophila, the only ciliated cells are sensory neurons and sperm. no mechanoreceptor potential (nomp) mutations have been isolated that affect the differentiation and function of ciliated sense organs. The nompB gene is here shown to encode an IFT protein. Its mutant phenotypes reveal the consequences of an IFT defect in an insect.


RESULTS
Mechanosensory and olfactory neurons in nompB mutants have missing or defective cilia. nompB encodes the Drosophila homolog of the IFT complex B protein IFT88/Polaris/OSM-5. nompB is expressed in the ciliated sensory neurons, and a functional, tagged NOMPB protein is located in sensory cilia and around basal bodies. Surprisingly, nompB mutant males produce normally elongated, motile sperm. Neuronally restricted expression and male germline mosaic experiments show that nompB-deficient sperm are fully functional in transfer, competition, and fertilization.


CONCLUSIONS
NOMPB, the Drosophila homolog of IFT88, is required for the assembly of sensory cilia but not for the extension or function of the sperm flagellum. Assembly of this extremely long axoneme is therefore independent of IFT.
Han
Young-Goo
YG
Graduate Program in Genetics, State University of New York at Stony Brook, Stony Brook, NY 11794, USA.
Kwok
Benjamin H
BH
Kernan
Maurice J
MJ
D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D002923:Cilia / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D004330:Drosophila; D004594:Electrophysiology; D005407:Flagella / Q000378:metabolism*; D040461:Gene Components; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D008297:Male; D008856:Microscopy, Fluorescence; D009475:Neurons, Afferent / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013094:Spermatozoa / Q000378:metabolism* / Q000502:physiology; D019076:Transgenes
D002352:Carrier Proteins; D018076:DNA, Complementary; D008164:Luminescent Proteins; C486142:NompB protein, Drosophila; D049452:Green Fluorescent Proteins