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 Staying in Shape
16.08.2018 | Max-Planck-Institut für molekulare Zellbiologie und Genetik

nachricht Chips, light and coding moves the front line in beating bacteria
16.08.2018 | Okinawa Institute of Science and Technology (OIST) Graduate 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: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Staying in Shape

16.08.2018 | Life Sciences

Diving robots find Antarctic seas exhale surprising amounts of carbon dioxide in winter

16.08.2018 | Earth Sciences

Protein droplets keep neurons at the ready and immune system in balance

16.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>