Table 1.
klar alleles
| Allele | Class | Screen | Mutagen | Molecular lesion | Localization embryo (Klar-M) | Localization ovary (Klar-C) |
|---|---|---|---|---|---|---|
| YG3 | I | Embryo | P excision [1] | ∼11kb deletion around exon 0 | Undetectable | Perinuclear |
| B | I | Embryo | EMS [1] | AA #210 Leu → Ter (exon 3) | Undetectable | Perinuclear |
| C | I | Embryo | EMS [1] | AA #210 Leu → Ter (exon 3) | Undetectable | Perinuclear |
| A | I | Embryo | EMS [1] | AA #221 Trp → Ter (exon 3) | Undetectable | Perinuclear |
| mBP | I | Eye | Hybrid dysgenesis [3] | between exons 4 and 5a | Undetectable | Perinuclear |
| mBX18 | I | Eye | X-rays [3] | between exons 4 and 5b | Undetectable | Perinuclear |
| mFN1 | I | Eye | EMS [3] | AA #1333 Gln → Ter (exon 11) | Undetectable | Perinuclear |
| D | I | Embryo | EMS [1] | AA #1430 Trp → Ter (exon 12) | Undetectable | Perinuclear |
| 1 | I | Embryo | EMS [2] | AA #1555 Gln → Ter (exon 14) | Even | Perinuclear |
| mBX3 | I | Eye | X-rays [3] | After AA #1598 fused to unrelated DNA (exon 14)c | Even | Perinuclear |
| mBX13 | II | Eye | X-rays [3] | Breakpoint between AA #1991 and #2062 (exon 18) | Basal | Undetectable |
| mCD4 | II | Eye | EMS [3] | AA #2203 Gln → Ter (exon 18) | Basal | Cytoplasm |
| mBX12 | II | Eye | X-rays [3] | Breakpoint between AA #2212 and #2226 (exon 18) | Basal | Undetectable |
The 13 klar alleles analyzed fall into two classes according to their effect on Klar staining and on droplet transport in embryos: Class I alleles have aberrant Klar staining and disrupt net apical droplet transport in phase III. Class II alleles have wild-type staining and support apical droplet transport. Both classes disrupt nuclear migration in eye imaginal disks. The table lists the origin of these alleles (type of screen and mutagenesis), their molecular lesions, and the observed immunostaining in early embryos and ovaries. The position of the lesion is given relative to the protein sequence of the originally reported Klar protein (Mosley-Bishop et al., 1999). Although these alleles might carry additional missense mutations in regions we did not sequence, the relative sizes of the mutant proteins on Western blots (Figure 1) are consistent with the notion that the premature stop codons or breakpoints we identified are responsible for the truncations. Ter, translation termination codon.
When the rough molecular mapping of the klarmBP breakpoint (Mosley-Bishop et al., 1999) is compared with the genomic sequence from FlyBase, it should fall between exons 4 and 5. This is consistent with the size of the mutant protein on Klar-N Westerns and the absence of signal on Klar-M Westerns
Rough molecular mapping puts the klarmBX18 lesion close to the klarmBP breakpoint (Mosley-Bishop et al., 1999). Our Western results are also consistent with a lesion between exon 4 and 5
klarmBX3 is due to a chromosomal transposition, originally mapped as Tp(3;3)61C4-7/87E6-F1 (Fischer-Vize and Mosley, 1994). We sequenced the exact breakpoint using inverse PCR; the encoded Klar protein is predicted to be normal up to AA #1598 and then fused to unrelated sequences derived from chromosomal region 70A1-B1. Notation for Klar-M staining: basal, Klar dots accumulate basally in phase II; even, Klar dots throughout peripheral cytoplasm. The Klar-C ovary staining pattern summarizes the major signal; the characteristics of additional Klar dots in the cytoplasm will be described elsewhere. [1], unpublished alleles generated by M. Welte and Y. Guo; [2], (Wieschaus and Nüsslein-Volhard, 1986); [3], (Fischer-Vize and Mosley, 1994)