Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lineage trees for cells

28.10.2005


Weizmann Institute scientists develop new analytical method

Some fundamental outstanding questions in science – "Where do stem cells originate?" "How does cancer develop?" "When do cell types split off from each other in the embryo?" – might be answered if scientists had a way to map the history of the body’s cells going back to the fertilized egg. Now, a multidisciplinary team at the Weizmann Institute of Science has developed an analytical method that can trace the lineage trees of cells.

This accomplishment started with a challenge to common wisdom, which says that every cell in an organism carries an exact duplicate of its genome. Although mistakes in copying, which are passed on to the next generation of cells as mutations, occur when cells divide, such tiny flaws in the genome are thought to be trivial and mainly irrelevant. But research students Dan Frumkin and Adam Wasserstrom of the Institute’s Biological Chemistry Department, working under the guidance of Prof. Ehud Shapiro of the Biological Chemistry and Computer Science and Applied Mathematics Departments, raised a new possibility: though biologically insignificant, the accumulated mutations might hold a record of the history of cell divisions. These findings were published today in PLoS Computational Biology.



Together with Prof. Uriel Feige of the Computer Science and Applied Mathematics Department and research student Shai Kaplan, they proved that these mutations can be treated as information and used to trace lineage on a large scale, and then applied the theory to extracting data and drafting lineage trees for living cells.

Methods employed until now for charting cell lineage have relied on direct observation of developing embryos. This method worked well enough for the tiny, transparent worm, C. elegans, which has a total of about 1,000 cells, but for humans, with 100 trillion cells, or even newborn mice or human embryos at one month, each of which has one billion cells after some 40 rounds of cell division, the task would be impossible.

The study focused on mutations in specific mutation-prone areas of the genome known as microsatellites. In microsatellites, a genetic "phrase" consisting of a few nucleotides (genetic "letters") is repeated over and over; mutations manifest themselves as additions or subtractions in length. Based on the current understanding of the mutation process in these segments, the scientists proved mathematically that microsatellites alone contain enough information to accurately plot the lineage tree for a one-billion-cell organism.

Both human and mouse genomes contain around 1.5 million microsatellites, but the team’s findings demonstrated that a useful analysis can be performed based on a much smaller number. To obtain a consistent mutation record, the team used organisms with a rare genetic defect found in plants and animals alike. While healthy cells have repair mechanisms to correct copying mistakes and prevent mutation, cells with the defect lack this ability, allowing mutations to accumulate relatively rapidly.

Borrowing a computer algorithm used by evolutionary biologists that analyzes genetic information in order to place organisms on branches of the evolutionary tree, the researchers assembled an automated system that samples the genetic material from a number of cells, compares it for specific mutations, applies the algorithm to assess degrees of relatedness, and then outlines the cell lineage tree. To check their system, they pitted it against the tried-and-true method of observing cell divisions as they occurred in a lab-grown cell culture. The team found that, from an analysis of just 50 microsatellites, they could successfully recreate an accurate cell lineage tree.

While the research team plans to continue to test their system on more complex organisms such as mice, several scientists have already expressed interest in integrating the method into ongoing research in their fields. Says Prof. Shapiro, who heads the project: "Our discovery may point the way to a future ’Human Cell Lineage Project’ that would aim to resolve fundamental open questions in biology and medicine by reconstructing ever larger portions of the human cell lineage tree."

Elizabeth McCrocklin | EurekAlert!
Further information:
http://www.weizmann.ac.il/udi/plos2005

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
21.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New bioimaging technique is fast and economical

21.08.2017 | Medical Engineering

Silk could improve sensitivity, flexibility of wearable body sensors

21.08.2017 | Materials Sciences

On the way to developing a new active ingredient against chronic infections

21.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>