Figure 4.

Induction of CI by transgenic cidA-cidB males. a. D. melanogaster males carrying transgenic cidA-cidB are sterile when mated to wild-type (WT) females (n=30 mating vials). Males with transgenic cidA-cidB* harboring the CidB active-site mutation C1025A (operon*) are fully fertile as are females with the active transgenic operon. CidA by itself has no effect on fertility; no strain singly transgenic for cidB could be isolated. EGFP is a negative control. Error bars are standard deviations. b. CI-like defects in the male pronucleus initially appear in late prophase, during the first division of the apposed female and male pronuclei, and accrue through mitosis. Abnormal cytology was observed in 56 transgenic CI embryos fixed after 18 min of development. c. Quantification of transgenic cidA-cidB (CI) embryos’ mitotic defects including uncondensed paternal chromosomes, delayed segregation of paternal chromosomes, or chromosomal bridging during the first zygotic cell cycle. Sample sizes of observed transgenic and WT embryos were 63 and 29, respectively. d. Quantification of developmental progress in transgenic (“CI”) embryos. At 24 h after egg laying, embryos were classified into three categories. Early, pre-blastoderm formation; Mid, blastoderm until segmentation stages; and Late, segmented stages. Quantification is based on three samples of approximately 200 embryos each. 60% of CI embryos arrested development in the early stage compared to 12% from the wild-type (WT) control. Significant p values (< 0.005) are indicated by (*). Error bars are standard deviations.