Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cells simply avoid chromosome confusion

16.09.2014

Reproductive cell division has a mechanical safeguard against errors

Reproductive cell division has evolved a simple, mechanical solution to avoid chromosome sorting errors, researchers report in the Sept. 11 Science Express.


This is atotal internal reflection fluorescence (TIRF) microscope used in Charles Asbury's lab at the University of Washington, where his team studies the molecular machinery of chromosome separation during reproductive cell division.

Credit: Charles Asbury

This natural safeguard prevents incorrect chromosome counts and misalignments that lead to infertility, miscarriage, or congenital conditions.

"Mistakes during reproductive cell division cause these problems, but what exactly goes wrong is often not understood," said Adele Marston of the Wellcome Trust Center for Cell Biology at the University of Edinburgh in Scotland and lead author of the study. Understanding normal protective mechanisms like the one newly discovered might suggest where things can go awry.

Marston is part of an international team studying meiosis – the type of cell division that splits an organism's original number of chromosomes in half for sexual reproduction. Meiosis occurs, for example, to create sperm or egg cells. The reduction allows offspring to inherit half their chromosomes from their father, and half from their mother.

"During cell division," she said, "chromosomes must be precisely sorted in an elaborate choreography where chromosomes pair up and then part in a sequence."

However, the arrangement gets complicated during the early stages of reproductive cell division. Instead of just pairs of chromosomes, the spindle-like apparatus in cells that pulls chromosomes apart has to deal with quartets. Each contains two 'sister chromatids' coming from the mother linked to two coming from the father A chromatid is either of the two strands formed when a chromosome is duplicated; sister chromatids are identical copies.

"The correct outcome for the first stage of meiosis," explained Dr. Charles L. Asbury, professor of physiology and biophysics at the University of Washington, "is for the sister chromatids to migrate together rather than to separate." Asbury is the senior author of the study.

In all types of cell division, he noted, sister chromatids are held together at first by cohesion. But in the earlier stages of reproductive cell division, the research team discovered that a strong, extra–tight linkage joins the sister chromatids.

When cells prepare to divide, molecular machines, called kinetochores, show up and assume several roles. They both control and drive chromosome movement. They set the timing for other cell division events, including the actual splitting of the chromosomes.

The kinetochores consist of an array of proteins that bind to the tips of miniscule, fiber-like structures called microtubules. The tips act as motors. The kinetochore converts the lengthening and shortening of the microtubules tips into useful force to move chromosomes.

The researchers determined that, during the early stages of meiosis, kinetochores between sister chromosomes mechanically fuse. The tethering keeps chromosomes from separating prematurely and ending up misplaced.

The fused kinetochores contain more binding elements than do single kinetochores, and form sturdy, hard-to-rupture attachments. A protein complex called monopolin is found inside cells during the early stages of reproductive cell division. It appears to be behind this modification. Monopolin alone was able to fuse kinetochore particles in a lab dish in the absence of other factors.

The researchers believe that the kinetochore fusion is a basic mechanism for the proper distribution of chromosomes in healthy cells. This feature of reproductive cell division is conserved across species and fundamental to carrying out expected patterns of genetic inheritance.

In this study, the researches worked with a simple life form, baker's yeast, and used advanced, highly sophisticated techniques. These included genetic manipulation, laser trapping and fluorescence microscopy.

"We combined genetic control of the cell cycle with biophysical manipulation of a complex protein machine – the kinetochore – at a single particle level," Asbury said. "I think our work will guide others who are studying molecular machineries that are regulated according to the cell cycle."

###

This research was supported by the Wellcome Trust, the National Institutes of Health, a Packard Fellowship, the Ludwig Institute for Cancer Research and the Sidney Kimmel Foundation.

In addition to Marston and Asbury, other key authors of the report are Krishna K. Sarangapani of the UW Department of Physiology and Biophysics in Seattle and Eris Duro of the University of Edinburgh. The other senior leader of the study was Sue Biggins of the Fred Hutchison Cancer Research Center in Seattle and the UW Department of Biochemistry.

Leila Gray | Eurek Alert!
Further information:
http://www.uw.edu

Further reports about: Cells Health Medicine Trust avoid chromosomes confusion kinetochore meiosis reproductive

More articles from Life Sciences:

nachricht Study shines light on brain cells that coordinate movement
26.06.2017 | University of Washington Health Sciences/UW Medicine

nachricht New insight into a central biological dogma on ion transport
26.06.2017 | Aarhus University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>