If you could peer microscopically into the closest freshwater pond, you'd hesitate before dipping a toe. Amid the murky water, you'd probably notice an oddly furry, pear-shaped organism gliding along--and gobbling up everything in its path.
This tiny predator has a big name--Tetrahymena thermophila--and a big fan club among scientists, as a star organism for research into how cells work.
Scientists have now sequenced, assembled, and analyzed T. thermophila's macronuclear genome. Their work, reported in today's issue of Public Library of Science (PLoS) Biology, explains the organism's impressive versatility. Rather than dividing labor into several types of cells, as humans and other multicellular organisms do, T. thermophila divides its activities, either into different places inside a cell or by changing the cell over time. It is a master multi-tasker.
"This organism is a true generalist," says evolutionary biologist Jonathan A. Eisen, who led the Tetrahymena project while at The Institute for Genomic Research (TIGR) and is now at the University of California, Davis. "Whatever this unicell touches with its hairlike projections, it will try to eat. If it does not bump into anything, the organism will seek out food with diverse sensory systems. It can protect itself from radiation and other threats and also can fight back against competitors and predators. In short, versatility is its strength. Now, we can understand how this versatility works."
It takes plenty of genes. In fact, T. thermophila has roughly 25,000 genes--nearly as many as humans do. Although the organism is single-celled, it contains a genetic repertoire of seemingly more complex organisms. It shares, with humans and other animals, many genes and processes typically absent in single-celled organisms. That means Tetrahymena may be an ideal model organism for studies of the processes these genes encode.
In the new study, genome analysis showed that one way that Tetrahymena adapts to diverse environments via gene duplication, a process that allows organisms to diversify pre-existing genes and adapt them for new functions. In the case of Tetrahymena, duplications appear to be concentrated in genes involved in sensing and responding to environment. From a small number of proteases (enzymes that degrade proteins), for instance, Tetrahymena has built an eating machine that allows it to digest nearly any protein it encounters.
Among its most quirky features, Tetrahymena has, inside each of its cells, two distinct nuclei, each with a different genome. Inside one nucleus, the "micronuclear" genome is reserved for sex and reproduction, remaining genetically silent during growth. Inside the second, working nucleus is the "macronuclear" genome, which expresses genes that govern behavior.
The current study sequenced the macronuclear genome, an impressively packaged bunch of coding genes, free of so-called junk DNA (noncoding sequences and other extraneous genetic elements) that litter the genomes of many organisms.
"Publication of the Tetrahymena genome marks the culmination of a remarkable collaboration within the research community," said Anthony Carter, Ph.D., of the National Institute of General Medical Sciences (NIGMS), which co-funded the project with the National Science Foundation (NSF). "Tetrahymena has a long and eminent history in the world of cell biology, and publication of its genome is likely to lead to further fundamental insights into how cells work."
Throughout the project, Eisen says, collaboration between researchers has been critical, including work by co-author Eduardo Orias of the University of California-Santa Barbara. The team emphasized open access to data, providing the genome sequence data to outside researchers, without restriction, since the project began in 2003. As a result, Tetrahymena researchers have already published dozens of studies making use of the genomic data. In addition to releasing the sequence data early on TIGR's website (www.tigr.org/tdb/e2k1/ttg/index.shtml) and via Genbank, the project also underwrote the creation of a major free community resource: The Tetrahymena Genome Database (TGD; http://ciliate.org/), headed by Mike Cherry at Stanford University. The publication in the open access journal PLoS Biology represents a commitment to free and open access to scientific literature as well. Now anyone, anywhere in the world, can read about the genome of this fascinating organism before meeting it in the local pond.
Kathryn Brown | EurekAlert!
Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel
Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences