Achiasmate meiosis and centromere shift in Eusimulium aureum (Diptera-Simuliidae).
Light and electronmicroscope studies indicate that Eusimulium aureum (n equals 2 metacentrics) is male-achiasmate. Supporting evidence for achiasmate meiosis includes lack of recombination between, I) widely separated differential segments of X and Y chromosomes and 2) linked autosomal inversions. In sibling C, chromosome II exists in an alternate "neoacrocentric" form interpreted as originating through the three-break shift of a small segment including centromere and nucleolar organizer. Male-achiasmate meiosis appears to be a prerequisite for the establishment of rearrangements that include large displacements of the centromere. This suggestion is supported by a correlation between achiasmate male meiosis and the fixation of gross pericentric changes in a number of other black fly species.
D000818:Animals; D002466:Cell Nucleolus; D007446:Chromosome Inversion; D002875:Chromosomes; D004175:Diptera / Q000196:embryology; D005260:Female; D008040:Genetic Linkage; D006570:Heterochromatin; D006579:Heterozygote; D007814:Larva; D008297:Male; D008540:Meiosis; D008853:Microscopy; D008854:Microscopy, Electron; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic; D012469:Salivary Glands; D012730:Sex Chromosomes; D013045:Species Specificity; D013091:Spermatogenesis
D006570:Heterochromatin