scholarly journals Another Case of Unequal Crossing-Over in Drosophila Melanogaster

2004 ◽  
pp. 35-38
Author(s):  
E. B. Lewis
Keyword(s):  
Drosophila Melanogaster ◽  
Crossing Over ◽  
Unequal Crossing Over

Variation among the dispersed (GATA)n sequences in Drosophila melanogaster

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 750-754 ◽  
Author(s):  
Paul R. Simpson
Keyword(s):  
Drosophila Melanogaster ◽  
Point Mutations ◽  
Repeated Sequence ◽  
Crossing Over ◽  
Unequal Crossing Over ◽  
Different Populations ◽  
Simple Repeats

Five nonallelic copies of the dispersed (GATA)n repeated sequence of Drosophila melanogaster (referred to as GATA elements) have been sequenced and analysed. The GATA elements range in size from 111 to 444 bp, consisting predominantly of tandemly repeated GATAs, interspersed with variants of the subunit. The types and distributions of these variants are consistent with the hypothesis that they have arisen by a random accumulation of point mutations (substitutions, deletions, and insertions) in pure (GATA)n sequences. Duplications or deletions of the GATA subunit, and of GATA variants, have also probably occurred, as a result of either unequal crossing-over or slipped-strand mispairing. Evidence for duplication (deletion) has been obtained from a comparison of two allelic GATA elements isolated from different populations. GATA elements, in common with other dispersed, simple repeats, are probably highly variable in length.Key words: simple sequences, GATA element, Drosophila.

scholarly journals Unequal crossing-over within the B duplication of Drosophila melanogaster: a molecular analysis

1991 ◽  
Vol 57 (2) ◽  
pp. 105-111 ◽  
Author(s):  
Stuart I. Tsubota
Keyword(s):  
Drosophila Melanogaster ◽  
Transposable Element ◽  
Molecular Analysis ◽  
Recombination Event ◽  
Tandem Duplication ◽  
Molecular Data ◽  
Crossing Over ◽  
Wild Type ◽  
Unequal Crossing Over ◽  
Extreme Form

SummaryThe B mutation is associated with a tandem duplication of 16A1–16A7. It is unstable, mutating to wild type and to a more extreme form at a frequency of one in 1000 to 3000. The reversion to wild type is associated with the loss of one copy of the duplication, whereas the mutation to extreme B is associated with a triplication of the region. The instability of B has been attributed to unequal crossing-over between the two copies of the duplication. Recent molecular data show that there is a transposable element, B104, between the two copies of the duplication and support the hypothesis that this element generated the duplication via a recombination event. These data suggest that unequal crossing-over within the duplication may not be the cause of the instability of B. Instead, the instability may be caused by a recombination event involving the B104 element. This issue was addressed using probes for the DNA on either side of the B104 element at the B breakpoint. All of the data indicate that the B104 element is not involved in the instability of B and support the original unequal crossing-over model.

The Rate of Unequal Crossing Over in the dumpy Gene from Drosophila melanogaster

2010 ◽  
Vol 70 (3) ◽  
pp. 260-265 ◽  
Author(s):  
Amber Carmon ◽  
Matthew Larson ◽  
Marta Wayne ◽  
Ross MacIntyre
Keyword(s):  
Drosophila Melanogaster ◽  
Crossing Over ◽  
Unequal Crossing Over

scholarly journals Population genetics of tandem repeats in centromeric heterochromatin: unequal crossing over and chromosomal divergence at the Responder locus of Drosophila melanogaster.

Genetics ◽  
1993 ◽  
Vol 135 (2) ◽  
pp. 477-487 ◽  
Author(s):  
E L Cabot ◽  
P Doshi ◽  
M L Wu ◽  
C I Wu
Keyword(s):  
Drosophila Melanogaster ◽  
Large Scale ◽  
Tandem Repeats ◽  
Evolutionary Dynamics ◽  
Repetitive Sequences ◽  
High Rate ◽  
Centromeric Heterochromatin ◽  
Crossing Over ◽  
Unequal Crossing Over ◽  
Left And Right

Abstract The Responder (Rsp) locus in Drosophila melanogaster is the target locus of segregation distortion and is known to be comprised of a tandem array of 120-bp repetitive sequences. In this study, we first determined the large scale molecular structure of the Rsp locus, which extends over a region of 600 kb on the standard sensitive (cn bw) chromosome. Within the region, small Rsp repeat arrays are interspersed with non-Rsp sequences and account for 10-20% of the total sequences. We isolated and sequenced 32 Rsp clones from three different chromosomes. The main results are: (1) Rsp repeats isolated from the same chromosome are not more similar than those from different chromosomes. This implies either that there are more homologous exchanges at the Rsp locus than expected or, alternatively, that the second chromosomes of D. melanogaster have diverged from one another more recently at the centromeric heterochromatin than at the nearby euchromatin. (2) The repeats usually have a dimeric structure with an average difference of 16% between the left and right halves. The differences allow us to easily identify the products of unequal exchanges. Despite the large differences between the two halves, exchanges have occurred frequently and the majority of them fall within a 29-bp interval of identity between the two halves. Our data thus support the suggestion that recombination depends on short stretches of complete identity rather than long stretches of general homology. (3) Frequent unequal crossover events obscure the phylogenetic relationships between repeats; therefore, different parts of any single repeat could often have different phylogenetic histories. The high rate of unequal crossing over may also help explain the evolutionary dynamics of the Rsp locus.

scholarly journals Bar reversion and hybrid dysgenesis in Drosophila melanogaster: reversion in males and in inversions

1983 ◽  
Vol 42 (1) ◽  
pp. 105-109 ◽  
Author(s):  
D. J. Colgan
Keyword(s):  
Drosophila Melanogaster ◽  
Hybrid Dysgenesis ◽  
Crossing Over ◽  
Unequal Crossing Over ◽  
Reduced Rate

SUMMARYThe effect of the P-M system of hybrid dysgenesis in Drosophila melanogaster on unequal crossing-over was studied using the Bar duplication. This system of dysgenesis had no demonstrable effect on the rate of Bar reversion. In the course of the study it was found that there was a greatly reduced rate of reversion in two homozygous inversion stocks. Further, one revertant was found which may result from unequal crossing over at the Bar locus in males.

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