Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hotspots found for chromosome gene swapping

03.12.2007
Work will lead to a better understanding of chromosome abnormalities and birth defects

Crossovers and double-strand DNA breaks do not occur randomly on yeast chromosomes during meiosis, but are greatly influenced by the proximity of the chromosome’s telomere, according to research in the laboratory of Whitehead Fellow Andreas Hochwagen. This work may lead to a better understanding of developmental chromosome abnormalities and birth defects.

Meiosis is a type of cell division that produces cells with only one copy of each chromosome—spores in yeast, and eggs and sperm in higher organisms.

During meiosis, chromosome pairs line up in the middle of the cell. The chromosome pairs are then pulled apart, with complete copies of all of the chromosomes ending up at opposite sides of the cell. To ensure that the chromosomes align properly in the middle of the cell, the chromosomes crossover—swap certain sections of genes. Without the crossovers, the chromosomes could misalign and both copies of a chromosome could end up in one cell. When this happens, the cells die or suffer from severe genetic problems, such as Down syndrome.

... more about:
»Blitzblau »Chromosome »DSB »Telomere »birth defect »breaks

Before a crossover can occur at a given site, both strands of a chromosome’s DNA helix must be broken. About half of these double-strand DNA breaks (DSBs) are processed to form crossovers, and the rest are resealed to restore the original chromosomes. The final number of crossovers is relatively small and scientists have long wondered how cells ensure that even the smallest chromosomes undergo at least one crossover. Indeed, in almost half of Down’s Syndrome cases, chromosome 21, one of the smallest human chromosomes, failed to form a crossover in one of the parents.

In a paper published online in Current Biology on November 29, Massachusetts Institute of Technology graduate student Hannah Blitzblau suggests that part of the answer lies in where DSBs are formed. Blitzblau has shown that these DSBs are not scattered randomly throughout the chromosomes, but occur most frequently in a specific band near telomeres, the end caps of chromosomes. When telomeres are spliced into the central part of a chromosome, this DSB “hotspot” effect is still seen at the same distance from the new telomeres.

“This is a simple mechanism for making sure that all chromosomes, even the shortest ones, have the crossovers required for meiosis,” says Blitzbau. “If the breaks occurred randomly, the smallest chromosomes often wouldn’t have any crossovers.”

In addition, Blitzblau showed that DSBs occur at high rates around the central part of the chromosome called the centromere, It was previously thought that DSBs and crossovers rarely occurred in this region.

“This is incredibly surprising,” says Hochwagen. “The chromosomes start the crossover process in the centromeres, but divert and reseal the breaks instead.”

Some of the earlier research had been done in mutant yeast strains; the Whitehead researchers say that the current work in non-mutant yeast is a more accurate representation of normal processes.

This research will help scientists understand chromosome events leading to infertility and birth defects. In addition, although this work does not touch on why some cells divide improperly, Blitzblau and Hochwagen anticipate that the technologies developed for this study will allow researchers to identify sites that are sensitive to breaks caused by agents, such as certain cancer drugs. The investigators are adapting the methods used in yeast to map break-sensitive sites in mammalian cells.

Eric Bender | EurekAlert!
Further information:
http://www.wi.mit.edu

Further reports about: Blitzblau Chromosome DSB Telomere birth defect breaks

More articles from Life Sciences:

nachricht Scientists spin artificial silk from whey protein
24.01.2017 | Deutsches Elektronen-Synchrotron DESY

nachricht Choreographing the microRNA-target dance
24.01.2017 | UT Southwestern Medical Center

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists spin artificial silk from whey protein

X-ray study throws light on key process for production

A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Breaking the optical bandwidth record of stable pulsed lasers

24.01.2017 | Physics and Astronomy

Choreographing the microRNA-target dance

24.01.2017 | Life Sciences

Spanish scientists create a 3-D bioprinter to print human skin

24.01.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>