Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Actin moves chromosomes: Discovery changes fundamental thinking

14.07.2005


Microtubules need a helping hand to find chromosomes in dividing egg cells, scientists have discovered. Although it was generally accepted that microtubules act alone as the cellular ropes to pull chromosomes into place, a new study by researchers at the European Molecular Biology Laboratory (EMBL) shows that this is not the case. They found that in large cells such as animal eggs, something else is needed to move the chromosomes into the correct location - fibres of the cytoskeletal molecule actin (Nature, July 13, 2005).



“No one has ever shown that actin moves chromosomes,” says Dr. Jan Ellenberg, the EMBL researcher whose group carried out the research. “We were able to do so because our group is one of the few that studies cell division in starfish - an ideal model for observing division in living animal eggs.”

The starfish is an excellent model for studying oocytes, the cells that give rise to egg cells. In this marine animal, these cells are transparent and mature quickly outside the body, and can be kept alive in a drop of seawater. That’s why EMBL scientists performed some of their experiments with collaborators at the Marine Biological Laboratory in Woods Hole, MA, USA – working with animals fresh from the ocean.


Ellenberg and PhD student Péter Lénárt studied the starfish oocytes as they underwent meiosis, a special cell division that is needed to halve the number of chromosomes in an egg before it unites with a sperm. When the protective nuclear membrane surrounding the chromosomes breaks down during meiosis, it was thought that microtubules capture the chromosomes and act as ropes to pull them to the surface and expel half of them from the cell.

But when the EMBL researchers measured the microtubules, they discovered that they were, in fact, much too short to transport the chromosomes over the long distance to the surface of the large oocyte. By using a chemical to disable the microtubules, they found that cells were still able to pull chromosomes into the proper positions.

So what was moving the chromosomes?

When they repeated the experiment with a chemical that breaks down the other major type of cellular fibres, actin, the cells lost track of their chromosomes and the new cells had unequal amounts of genetic material. This condition, called aneuploidy, is thought to be a major cause of miscarriages and some types of birth defects.

Lénárt spent 18 months optimizing an imaging technology, with help from collaborators at the German Cancer Research Center (DKFZ), to visualize the delicate actin fibres before he could confirm the group’s fundamental breakthrough. He observed a network of filamentous actin forming in the region where the nuclear membrane breaks down. This network acts as a fishnet to gather all the chromosomes together and drag them close to the short microtubules. Only then, when the chromosomes are close enough, can the microtubules latch on and pull half of them outside the cell.

The implications for this pioneering work are clear. Starfish oocytes have many similarities to those of other animals, including humans. Because this mechanism is essential to prevent chromosome loss before fertilization, advances in this field could help to explain the causes of pregnancy loss and birth defects in humans.

Trista Dawson | alfa
Further information:
http://www.embl.de

More articles from Life Sciences:

nachricht Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View
22.06.2018 | University of Sussex

nachricht New cellular pathway helps explain how inflammation leads to artery disease
22.06.2018 | Cedars-Sinai 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: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>