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.
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Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
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