MOLECULAR ANALYSIS OF CUBITUS INTERRUPTUS (CI) MUTATIONS SUGGESTS AN EXPLANATION FOR THE UNUSUAL CI POSITION EFFECTS

被引:32
作者
LOCKE, J [1 ]
TARTOF, KD [1 ]
机构
[1] FOX CHASE CANC CTR,INST CANC RES,PHILADELPHIA,PA 19111
来源
MOLECULAR & GENERAL GENETICS | 1994年 / 243卷 / 02期
关键词
DROSOPHILA MELANOGASTER; CI(D)-CE-2 LOCUS; CUBITUS INTERRUPTUS; SEGMENTATION GENE; CHROMOSOME; 4;
D O I
10.1007/BF00280321
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The cubitus interruptus (ci) locus of Drosophila melanogaster is located proximally on chromosome 4. In ci mutants cubital wing veins are interrupted or absent. We have cloned this locus using a gypsy element associated with the ci(1) mutation. Analysis of all extant ci mutations reveals that they contain conspicuous molecular alterations within a 13.7 kb region. Of the four homozygous viable mutations, three (ci(1), Ci(361), Ci(W)) have single insertions, while one (Ci(57g)) has a small deletion, all located within a more restricted 1 kb region. The dominant mutations, ci(D) and Ce-2 each contain two insertions within the 13.7 kb region. All these molecular alterations are located upstream of a transcript previously associated with the ci(D) mutation and thought to derive from a segment polarity gene. We induced revertants of the dominant ci phenotype (wing vein interruption) in ci(D) and found molecular alterations in this transcript (the cif transcript) in two revertant alleles, thereby demonstrating this transcript's involvement in the ci phenotype. The locations of the molecular alterations, together with the results of the ci(D) reversion experiment, provide a connection between the dominant and recessive ci mutations and argue that all are likely to be alleles of the same complex locus, ci, not two separate loci as previously proposed. The ci phenotype of dominant and recessive mutations can be explained by inappropriate expression of the cit transcript in the posterior wing compartment where the cubital vein is affected, while loss of ci(+) function generates recessive lethality. Lack of repression of ci(+) transcription, through a pairing-dependent, trans-acting silencer element, can explain the unusual position effects associated.with ci (the Dubinin effect).
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页码:234 / 243
页数:10
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