|Feature type||allele||Associated gene||Dmel\SAK|
|Map ( GBrowse )||
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|Nature of the Allele|
|Mutations Mapped to the Genome|
|Associated Sequence Data|
|Nature of the lesion|
|Caused by insertion|
|Phenotype Manifest In|
astral microtubule & primary spermatocyte
centriole & larval brain
centriole & primary spermatocyte
centrosome & larval brain
centrosome & primary spermatocyte
spindle & larval brain
spindle & primary spermatocyte
Mutants have a reduced number of centrioles in spermatocytes and reduced proximal centriole-like formation in spermatids.
68% of SAK[c06612] mutant primary spermatocytes do not have centrioles. All of the acentriolar spindles analysed are abnormal and these abnormal spindles result in dramatic chromosome segregation defects. Spermatids from SAK[c06612] mutants frequently have multiple nuclei of differing sizes indicative of unequal partitioning of chromosomes in meiosis. Embryos derived from homozygous SAK[c06612] mutant mothers contain very few spindles, with a maximum of 16 spindles compared to up to 8000 in wild type. These spindles are abnormally shaped with broad poles lacking centrioles. Free asters are also observed in 57% of SAK[c06612] mutant embryos, and these contain only one centriole, compared to the two centrioles seen at wild type spindle poles. All mutant embryos become arrested in mitosis and fail to develop.
Mitotic cells in larval brains of SAKc06612 flies can lack centrosomes and show both focused and splayed poles. These cells often have two, one, or zero centrosomes and lack centrioles. The brains of mutant larvae are of normal size and the proportion of brain cells in mitosis is similar to wild-type brains, indicating no obvious defects in cell-cycle progression. A high proportion of SAKc06612 primary spermatocytes have no centrioles at one or both spindles in meiosis I. When centrioles are absent, the spindle poles are broad. There are either no astral microtubules, or disorganized spindles are formed. SAKc06612 mutants lose their centrioles during the mitotic divisions preceding male meiosis but still produce cysts of 16 primary spermatocytes as in the wild type. The absence of centrioles prevents the mutant spermatids from making sperm axonemes. Cells that have no axonemes have irregular size and numbers of mitochondrial derivatives per cell. The majority of sperm from SAKc06612 mutant testes are nonmotile, leading to male sterility. Mathematical modeling of the stereotyped cell divisions of spermatogenesis can account for centriole loss by defective centriole duplication.
SAKc06612/Df(3L)Pc-2q mutants pupate 1 day later than SAKc06612/+ or Df(3L)Pc-2q/+ heterozygotes. Although all SAKc06612/Df(3L)Pc-2q flies eclose, the majority of adults are uncoordinated and die after getting stuck in food. 75% of SAKc06612 homozygotes survive after eclosion. The brains of SAKc06612 flies show centrosome defects in mitotic cells; this effect is greater in hemizygous flies.
|Phenotype Manifest In|
|Complementation & Rescue Data|
|Stocks ( 2 )|
|Notes on Origin|
|External Crossreferences & Linkouts|
|Synonyms & Secondary IDs ( 2 )|
|Secondary FlyBase IDs|
|References ( 7 )|
|Personal communication to FlyBase|