Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers sequence the basal eukaryote Tetrahymena thermophila

30.08.2006
In an effort to improve our understanding of eukaryotic evolution, a team of over 50 researchers led by Jonathan Eisen sequenced the macronuclear genome of the single-celled ciliate Tetrahymena themophila. Published online this week in the open-access journal PLoS Biology, the authors provide insights into the biology of this organism.

T. thermophila is particularly unusual inside. Each cell contains two nuclei: a micronucleus comprising only five chromosomes, and a macronucleus, which has more than 200. The micronucleus contains the DNA necessary for reproduction. The macronucleus controls the cell's other functions. When the cells mate, the micronucleus splinters into fragments, which in turn replicate to form many smaller chromosomes that become the macronucleus.

The researchers carried out shotgun sequencing on purified macronuclei DNA and then reconstructed the genome using computational techniques. They captured an estimated 95% of the genome and conclude it is 105 million base pairs in length and between 185 and 287 total chromosomes. The chromosomes lack centromeres (presumably as they do not undergo meiosis or mitosis), and have only a very small amount of repetitive DNA (much of it is excised from the micronucleus during macronucleus formation). The genome encodes over 27,000 protein-coding genes with some gene families having undergone expansion as exemplified by the more than 300 voltage-gated ion channels that control membrane transport--a critical function for this single-celled organism.

T. thermophila is known to only employ one stop codon (UGA) during protein synthesis; the two unused ones code for glutamine. As UGA can also code for selenocysteine, this is the only organism known so far to translate all 64 codons.

The sequenced genome permitted the authors to investigate plastid acquisition in the alveolates--a group of three related phyla, ciliates, apicomplexans (parasites including malaria causing Plasmodium), and dinoflagellates (oceanic photosynthetic protozoans). Plastids like chloroplasts are organelles descended from free-living cyanobacteria. Many of the genes are typically incorporated into the host nucleus. No evidence of plastids was found in T. thermophila, although they are present in both apicomplexans and dinoflagellates, indicating that plastid acquisition most likely occurred after they had split from the ciliates.

As a basal eukaryote, this genome will enable studies on eukaryotic evolution. The authors aim to next sequence the micronuclear genome.

Natalie Bouaravong | EurekAlert!
Further information:
http://www.plos.org
http://www.plosbiology.org

Further reports about: chromosomes ciliate macronucleus micronucleus thermophila

More articles from Life Sciences:

nachricht Viruses support photosynthesis in bacteria – an evolutionary advantage?
23.02.2017 | Technische Universität Kaiserslautern

nachricht Scientists unlock ability to generate new sensory hair cells
22.02.2017 | Brigham and Women's Hospital

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>