Distribution of Induced Breaks along the
            <i>X</i>
            -Chromosome of Drosophila Melanogaster

Kaufmann, Berwind Petersen

doi:10.1073/pnas.25.11.571

Cited by 91 publications

(34 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…2D), ∼33% of the large dense bands on the chromosome comprise UR regions. A substantial number of euchromatic regions defined by preferential breakage, late replication, etc., have been termed "intercalary heterochromatin" (Kaufmann 1939;Zhimulev and Belyaeva 2003) and ∼25% of these correspond to UR regions (Belyakin et al 2005). Consistent with this, the mapping presented here shows that a region's chromatin state is not a good predictor of whether it will underreplicate.…”

Section: Ur Domains Correspond To Major Bandssupporting

confidence: 72%

Polytene Chromosome Structure and Somatic Genome Instability

Spradling

2017

Cold Spring Harb Symp Quant Biol

View full text Add to dashboard Cite

Polytene chromosomes have for 80 years provided the highest resolution view of interphase genome structure in an animal cell nucleus. These chromosomes represent the normal genomic state of nearly all Drosophila larval and many adult cells, and a better understanding of their striking banded structure has been sought for decades. A more recently appreciated characteristic of Drosophila polytene cells is somatic genome instability caused by unfinished replication (UR). Repair of stalled forks generates enough deletions in polytene salivary gland cells to alter 10%-90% of the DNA strands within more than 100 UR regions comprising 20% of the euchromatic genome. We accurately map UR regions and show that most approximate large polytene bands, indicating that replication forks frequently stall near band boundaries in late S phase. Chromosome conformation capture has recently identified dense topologically associated domains (TADs) in many genomes and most UR bands are similar or slightly smaller than a cognate Drosophila TAD. We argue that bands serve the evolutionarily ancient function of coordinating genome replication with local gene activity. We also discuss the relatively recent evolution of polyteny and somatic instability in Diptera and propose that these processes helped propel the amazing success of two-winged flies in becoming the most ecologically diverse insect group, with 200 times the number of species as mammals.

show abstract

Section: Ur Domains Correspond To Major Bandssupporting

confidence: 72%

Polytene Chromosome Structure and Somatic Genome Instability

Spradling

2017

Cold Spring Harb Symp Quant Biol

View full text Add to dashboard Cite

show abstract

“…The tandem repeat formation step would then be followed by a duplication of the tandem array, thus relocating the cluster to a euchromatic region into the middle of the X arm. The high SD density observed in this region can be also explained by Kaufmann's studies (Kaufmann 1939) on break frequencies along the X chromosome. A high break frequency is observed in this region, as in heterochromatin.…”

Section: Tandem Duplicationssupporting

confidence: 52%

“…This region is also known to be under-replicated in polytene chromosomes, a hallmark of a heterochromatic state (Ashburner 1989). Kaufmann (1939) also suggests that this region contains heterochromatic material to explain a high break frequency observed in the central region of the X chromosome (cytogenetic map: from 10F to 13A). This region encompasses a cluster of tandemly repeated Stellate genes.…”

Section: Sd Enrichment Within Heterochromatic Regionsmentioning

confidence: 96%

A model of segmental duplication formation in Drosophila melanogaster

Fiston-Lavier¹,

Anxolabéhère²,

Quesneville³

2007

Genome Res.

View full text Add to dashboard Cite

Segmental duplications (SDs) are low-copy repeats of DNA segments that have long been recognized to be involved in genome organization and evolution. But, to date, the mechanism of their formation remains obscure. We propose a model for SD formation that we name "duplication-dependent strand annealing" (DDSA). This model is a variant of the synthesis-dependent strand annealing (SDSA) model-a double-strand break (DSB) homologous repair model. DSB repair in Drosophila melanogaster genome usually occurs primarily through homologous repair, more preferentially through the SDSA model. The DDSA model predicts that after a DSB, the search for an ectopic homologous region-here a repeat-initiates the repair. As expected by the model, the analysis of SDs detected by a computational analysis of the D. melanogaster genome indicates a high enrichment in transposable elements at SD ends. It shows moreover a preferential location of SDs in heterochromatic regions. The model has the advantage of also predicting specific traces left during synthesis. The observed traces support the DDSA model as one model of formation of SDs in D. melanogaster genome. The analysis of these DDSA signatures suggests moreover a sequestration of the dissociated strand in the repair complex.

show abstract

“…In salivary gland polytene chromosomes, there are a few dozen sites throughout the genome that possess a unique set of properties, which include "weakness" in squashed chromosome preparations, under-replication, and late replication. These sites have been termed intercalary heterochromatin (IH) (Bridges 1935;Kaufmann 1939;Zhimulev et al 1982;Hammond and Laird 1985;Lamb and Laird 1987). The clustered breakpoints in polytene regions 10 and 11 surround a notable "weak point" and site of underreplication in 11A.…”

Section: Discussionmentioning

confidence: 99%

Preferential Breakpoints in the Recovery of Broken Dicentric Chromosomes inDrosophila melanogaster

Hill¹,

Golic

2015

Genetics

View full text Add to dashboard Cite

We designed a system to determine whether dicentric chromosomes in Drosophila melanogaster break at random or at preferred sites. Sister chromatid exchange in a Ring-X chromosome produced dicentric chromosomes with two bridging arms connecting segregating centromeres as cells divide. This double bridge can break in mitosis. A genetic screen recovered chromosomes that were linearized by breakage in the male germline. Because the screen required viability of males with this X chromosome, the breakpoints in each arm of the double bridge must be closely matched to produce a nearly euploid chromosome. We expected that most linear chromosomes would be broken in heterochromatin because there are no vital genes in heterochromatin, and breakpoint distribution would be relatively unconstrained. Surprisingly, approximately half the breakpoints are found in euchromatin, and the breakpoints are clustered in just a few regions of the chromosome that closely match regions identified as intercalary heterochromatin. The results support the Laird hypothesis that intercalary heterochromatin can explain fragile sites in mitotic chromosomes, including fragile X. Opened rings also were recovered after male larvae were exposed to X-rays. This method was much less efficient and produced chromosomes with a strikingly different array of breakpoints, with almost all located in heterochromatin. A series of circularly permuted linear X chromosomes was generated that may be useful for investigating aspects of chromosome behavior, such as crossover distribution and interference in meiosis, or questions of nuclear organization and function.KEYWORDS dicentric chromosome; intercalary heterochromatin; fragile X; FLP D ROSOPHILA is noted for a combination of facile genetics and high-resolution cytology that allows the recovery and characterization of a variety of chromosome rearrangements. Simple structural changes such as duplications, deficiencies, inversions, and translocations are readily produced through a variety of classical and modern techniques. More complex rearrangements such as balancers, compound chromosomes, and ring chromosomes also have been generated. Ring chromosomes historically have been of interest for a number of unique properties, such as a propensity for loss during early embryonic mitoses and dominant zygotic lethality (Leigh 1976;Ashburner et al. 2005). Despite their "instability," ring chromosome stocks can be remarkably stable, with very few reported instances of spontaneous opening into linear chromosomes.In this work, we produced a number of linearized ring chromosomes. One goal was to determine whether there are preferred sites of breakage for dicentric chromosomes. Although we have previously shown that dicentric Y, 3, and 4 chromosomes can break and heal in the male germline and be recovered in offspring, these chromosomes allowed little opportunity to determine whether there were preferred sites of breakage (Ahmad and Golic 1998; Golic 2008, 2010;Titen et al. 2014). In the case of the Y chromosome, low r...

show abstract

Distribution of Induced Breaks along the X -Chromosome of Drosophila Melanogaster

Cited by 91 publications

References 2 publications

Polytene Chromosome Structure and Somatic Genome Instability

Polytene Chromosome Structure and Somatic Genome Instability

A model of segmental duplication formation in Drosophila melanogaster

Preferential Breakpoints in the Recovery of Broken Dicentric Chromosomes inDrosophila melanogaster

Contact Info

Product

Resources

About